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Frederiksen JH, Jensen SB, Tümer Z, Hansen TVO. Classification of MSH6 Variants of Uncertain Significance Using Functional Assays. Int J Mol Sci 2021; 22:ijms22168627. [PMID: 34445333 PMCID: PMC8395337 DOI: 10.3390/ijms22168627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/27/2021] [Indexed: 12/20/2022] Open
Abstract
Lynch syndrome (LS) is one of the most common hereditary cancer predisposition syndromes worldwide. Individuals with LS have a high risk of developing colorectal or endometrial cancer, as well as several other cancers. LS is caused by autosomal dominant pathogenic variants in one of the DNA mismatch repair (MMR) genes MLH1, MSH2, PMS2 or MSH6, and typically include truncating variants, such as frameshift, nonsense or splicing variants. However, a significant number of missense, intronic, or silent variants, or small in-frame insertions/deletions, are detected during genetic screening of the MMR genes. The clinical effects of these variants are often more difficult to predict, and a large fraction of these variants are classified as variants of uncertain significance (VUS). It is pivotal for the clinical management of LS patients to have a clear genetic diagnosis, since patients benefit widely from screening, preventive and personal therapeutic measures. Moreover, in families where a pathogenic variant is identified, testing can be offered to family members, where non-carriers can be spared frequent surveillance, while carriers can be included in cancer surveillance programs. It is therefore important to reclassify VUSs, and, in this regard, functional assays can provide insight into the effect of a variant on the protein or mRNA level. Here, we briefly describe the disorders that are related to MMR deficiency, as well as the structure and function of MSH6. Moreover, we review the functional assays that are used to examine VUS identified in MSH6 and discuss the results obtained in relation to the ACMG/AMP PS3/BS3 criterion. We also provide a compiled list of the MSH6 variants examined by these assays. Finally, we provide a future perspective on high-throughput functional analyses with specific emphasis on the MMR genes.
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Affiliation(s)
- Jane H. Frederiksen
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (S.B.J.); (Z.T.)
- Department of Pediatrics and Adolescent Medicine, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
- Correspondence: (J.H.F.); (T.v.O.H.)
| | - Sara B. Jensen
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (S.B.J.); (Z.T.)
| | - Zeynep Tümer
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (S.B.J.); (Z.T.)
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Thomas v. O. Hansen
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark; (S.B.J.); (Z.T.)
- Department of Pediatrics and Adolescent Medicine, Copenhagen University Hospital, Rigshospitalet, DK-2100 Copenhagen, Denmark
- Correspondence: (J.H.F.); (T.v.O.H.)
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Blunder S, Pavel P, Minzaghi D, Dubrac S. PPARdelta in Affected Atopic Dermatitis and Psoriasis: A Possible Role in Metabolic Reprograming. Int J Mol Sci 2021; 22:7354. [PMID: 34298981 PMCID: PMC8303290 DOI: 10.3390/ijms22147354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 12/16/2022] Open
Abstract
Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors expressed in the skin. Three PPAR isotypes, α (NRC1C1), β or δ (NRC1C2) and γ (NRC1C3), have been identified. After activation through ligand binding, PPARs heterodimerize with the 9-cis-retinoic acid receptor (RXR), another nuclear hormone receptor, to bind to specific PPAR-responsive elements in regulatory regions of target genes mainly involved in organogenesis, cell proliferation, cell differentiation, inflammation and metabolism of lipids or carbohydrates. Endogenous PPAR ligands are fatty acids and fatty acid metabolites. In past years, much emphasis has been given to PPARα and γ in skin diseases. PPARβ/δ is the least studied PPAR family member in the skin despite its key role in several important pathways regulating inflammation, keratinocyte proliferation and differentiation, metabolism and the oxidative stress response. This review focuses on the role of PPARβ/δ in keratinocytes and its involvement in psoriasis and atopic dermatitis. Moreover, the relevance of targeting PPARβ/δ to alleviate skin inflammation is discussed.
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Affiliation(s)
| | | | | | - Sandrine Dubrac
- Epidermal Biology Laboratory, Department of Dermatology, Venereology and Allergology, Medical University of Innsbruck, Anichstraße 35, 6020 Innsbruck, Austria; (S.B.); (P.P.); (D.M.)
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3
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Tibbe D, Pan YE, Reißner C, Harms FL, Kreienkamp HJ. Functional analysis of CASK transcript variants expressed in human brain. PLoS One 2021; 16:e0253223. [PMID: 34133460 PMCID: PMC8208546 DOI: 10.1371/journal.pone.0253223] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 05/31/2021] [Indexed: 11/23/2022] Open
Abstract
The calcium-/calmodulin dependent serine protein kinase (CASK) belongs to the membrane-associated guanylate kinases (MAGUK) family of proteins. It fulfils several different cellular functions, ranging from acting as a scaffold protein to transcription control, as well as regulation of receptor sorting. CASK functions depend on the interaction with a variety of partners, for example neurexin, liprin-α, Tbr1 and SAP97. So far, it is uncertain how these seemingly unrelated interactions and resulting functions of CASK are regulated. Here, we show that alternative splicing of CASK can guide the binding affinity of CASK isoforms to distinct interaction partners. We report seven different variants of CASK expressed in the fetal human brain. Four out of these variants are not present in the NCBI GenBank database as known human variants. Functional analyses showed that alternative splicing affected the affinities of CASK variants for several of the tested interaction partners. Thus, we observed a clear correlation of the presence of one splice insert with poor binding of CASK to SAP97, supported by molecular modelling. The alternative splicing and distinct properties of CASK variants in terms of protein-protein interaction should be taken into consideration for future studies.
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Affiliation(s)
- Debora Tibbe
- Institut für Humangenetik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Yingzhou Edward Pan
- Institut für Humangenetik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Carsten Reißner
- Institut für Anatomie und Molekulare Neurobiologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Frederike L. Harms
- Institut für Humangenetik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
| | - Hans-Jürgen Kreienkamp
- Institut für Humangenetik, Universitätsklinikum Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
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da Silva IV, Silva AG, Pimpão C, Soveral G. Skin aquaporins as druggable targets: Promoting health by addressing the disease. Biochimie 2021; 188:35-44. [PMID: 34097985 DOI: 10.1016/j.biochi.2021.05.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/18/2021] [Accepted: 05/31/2021] [Indexed: 12/17/2022]
Abstract
Skin is the most vulnerable organ of the human body since it is the first line of defense, covering the entire external body surface. Additionally, skin has a critical role in thermoregulation, sensation, immunological surveillance, and biochemical processes such as Vitamin D3 production by ultraviolet irradiation. The ability of the skin layers and resident cells to maintain skin physiology, such as hydration, regulation of keratinocytes proliferation and differentiation and wound healing, is supported by key proteins such as aquaporins (AQPs) that facilitate the movements of water and small neutral solutes across membranes. Various AQP isoforms have been detected in different skin-resident cells where they perform specific roles, and their dysregulation has been associated with several skin pathologies. This review summarizes the current knowledge of AQPs involvement in skin physiology and pathology, highlighting their potential as druggable targets for the treatment of skin disorders.
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Affiliation(s)
- Inês V da Silva
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal; Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal.
| | - Andreia G Silva
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal; Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal
| | - Catarina Pimpão
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal; Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal
| | - Graça Soveral
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal; Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, 1649-003, Lisboa, Portugal.
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Liu S, Zhou M, Ruan Z, Wang Y, Chang C, Sasaki M, Rajaram V, Lemoff A, Nambiar K, Wang JE, Hatanpaa KJ, Luo W, Dawson TM, Dawson VL, Wang Y. AIF3 splicing switch triggers neurodegeneration. Mol Neurodegener 2021; 16:25. [PMID: 33853653 PMCID: PMC8048367 DOI: 10.1186/s13024-021-00442-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 03/12/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Apoptosis-inducing factor (AIF), as a mitochondrial flavoprotein, plays a fundamental role in mitochondrial bioenergetics that is critical for cell survival and also mediates caspase-independent cell death once it is released from mitochondria and translocated to the nucleus under ischemic stroke or neurodegenerative diseases. Although alternative splicing regulation of AIF has been implicated, it remains unknown which AIF splicing isoform will be induced under pathological conditions and how it impacts mitochondrial functions and neurodegeneration in adult brain. METHODS AIF splicing induction in brain was determined by multiple approaches including 5' RACE, Sanger sequencing, splicing-specific PCR assay and bottom-up proteomic analysis. The role of AIF splicing in mitochondria and neurodegeneration was determined by its biochemical properties, cell death analysis, morphological and functional alterations and animal behavior. Three animal models, including loss-of-function harlequin model, gain-of-function AIF3 knockin model and conditional inducible AIF splicing model established using either Cre-loxp recombination or CRISPR/Cas9 techniques, were applied to explore underlying mechanisms of AIF splicing-induced neurodegeneration. RESULTS We identified a nature splicing AIF isoform lacking exons 2 and 3 named as AIF3. AIF3 was undetectable under physiological conditions but its expression was increased in mouse and human postmortem brain after stroke. AIF3 splicing in mouse brain caused enlarged ventricles and severe neurodegeneration in the forebrain regions. These AIF3 splicing mice died 2-4 months after birth. AIF3 splicing-triggered neurodegeneration involves both mitochondrial dysfunction and AIF3 nuclear translocation. We showed that AIF3 inhibited NADH oxidase activity, ATP production, oxygen consumption, and mitochondrial biogenesis. In addition, expression of AIF3 significantly increased chromatin condensation and nuclear shrinkage leading to neuronal cell death. However, loss-of-AIF alone in harlequin or gain-of-AIF3 alone in AIF3 knockin mice did not cause robust neurodegeneration as that observed in AIF3 splicing mice. CONCLUSIONS We identified AIF3 as a disease-inducible isoform and established AIF3 splicing mouse model. The molecular mechanism underlying AIF3 splicing-induced neurodegeneration involves mitochondrial dysfunction and AIF3 nuclear translocation resulting from the synergistic effect of loss-of-AIF and gain-of-AIF3. Our study provides a valuable tool to understand the role of AIF3 splicing in brain and a potential therapeutic target to prevent/delay the progress of neurodegenerative diseases.
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Affiliation(s)
- Shuiqiao Liu
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Mi Zhou
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Zhi Ruan
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Yanan Wang
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Calvin Chang
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Masayuki Sasaki
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Veena Rajaram
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Andrew Lemoff
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Kalyani Nambiar
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Jennifer E. Wang
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Kimmo J. Hatanpaa
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Weibo Luo
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Ted M. Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Valina L. Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Yingfei Wang
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
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Bhattacherjee A, Jung J, Zia S, Ho M, Eskandari-Sedighi G, St. Laurent CD, McCord KA, Bains A, Sidhu G, Sarkar S, Plemel JR, Macauley MS. The CD33 short isoform is a gain-of-function variant that enhances Aβ 1-42 phagocytosis in microglia. Mol Neurodegener 2021; 16:19. [PMID: 33766097 PMCID: PMC7992807 DOI: 10.1186/s13024-021-00443-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 03/12/2021] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND CD33 is genetically linked to Alzheimer's disease (AD) susceptibility through differential expression of isoforms in microglia. The role of the human CD33 short isoform (hCD33m), preferentially encoded by an AD-protective CD33 allele (rs12459419T), is unknown. Here, we test whether hCD33m represents a loss-of-function or gain-of-function variant. METHODS We have developed two models to test the role of hCD33m. The first is a new strain of transgenic mice expressing hCD33m in the microglial cell lineage. The second is U937 cells where the CD33 gene was disrupted by CRISPR/Cas9 and complemented with different variants of hCD33. Primary microglia and U937 cells were tested in phagocytosis assays and single cell RNA sequencing (scRNAseq) was carried out on the primary microglia. Furthermore, a new monoclonal antibody was developed to detect hCD33m more efficiently. RESULTS In both primary microglia and U937 cells, we find that hCD33m enhances phagocytosis. This contrasts with the human CD33 long isoform (hCD33M) that represses phagocytosis, as previously demonstrated. As revealed by scRNAseq, hCD33m+ microglia are enriched in a cluster of cells defined by an upregulated expression and gene regulatory network of immediate early genes, which was further validated within microglia in situ. Using a new hCD33m-specific antibody enabled hCD33m expression to be examined, demonstrating a preference for an intracellular location. Moreover, this newly discovered gain-of-function role for hCD33m is dependent on its cytoplasmic signaling motifs, dominant over hCD33M, and not due to loss of glycan ligand binding. CONCLUSIONS These results provide strong support that hCD33m represents a gain-of-function isoform and offers insight into what it may take to therapeutically capture the AD-protective CD33 allele.
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Affiliation(s)
- Abhishek Bhattacherjee
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Jaesoo Jung
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Sameera Zia
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, T6G 2E1 Canada
| | - Madelene Ho
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, T6G 2E1 Canada
| | - Ghazaleh Eskandari-Sedighi
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Chris D. St. Laurent
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Kelli A. McCord
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Arjun Bains
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Gaurav Sidhu
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Susmita Sarkar
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
| | - Jason R. Plemel
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, T6G 2E1 Canada
- Department of Medicine, Division of Neurology, University of Alberta, Edmonton, T6G 2E1 Canada
| | - Matthew S. Macauley
- Department of Chemistry, University of Alberta, 11227 Saskatchewan Dr., Gunning Lemieux Chemistry Centre E5-18A, Edmonton, T6G 2G2 Canada
- Department of Medical Microbiology and Immunology, Edmonton, T6G 2E1 Canada
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7
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Nagandla H, Robertson MJ, Putluri V, Putluri N, Coarfa C, Weigel NL. Isoform-specific Activities of Androgen Receptor and its Splice Variants in Prostate Cancer Cells. Endocrinology 2021; 162:6029774. [PMID: 33300995 PMCID: PMC8253248 DOI: 10.1210/endocr/bqaa227] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Indexed: 12/18/2022]
Abstract
Androgen receptor (AR) signaling continues to drive castration-resistant prostate cancer (CRPC) in spite of androgen deprivation therapy (ADT). Constitutively active shorter variants of AR, lacking the ligand binding domain, are frequently expressed in CRPC and have emerged as a potential mechanism for prostate cancer to escape ADT. ARv7 and ARv567es are 2 of the most commonly detected variants of AR in clinical samples of advanced, metastatic prostate cancer. It is not clear if variants of AR merely act as weaker substitutes for AR or can mediate unique isoform-specific activities different from AR. In this study, we employed LNCaP prostate cancer cell lines with inducible expression of ARv7 or ARv567es to delineate similarities and differences in transcriptomics, metabolomics, and lipidomics resulting from the activation of AR, ARv7, or ARv567es. While the majority of target genes were similarly regulated by the action of all 3 isoforms, we found a clear difference in transcriptomic activities of AR versus the variants, and a few differences between ARv7 and ARv567es. Some of the target gene regulation by AR isoforms was similar in the VCaP background as well. Differences in downstream activities of AR isoforms were also evident from comparison of the metabolome and lipidome in an LNCaP model. Overall our study implies that shorter variants of AR are capable of mediating unique downstream activities different from AR and some of these are isoform specific.
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Affiliation(s)
- Harika Nagandla
- Department of Molecular and Cellular Biology, Baylor
College of Medicine, Houston, TX, USA
| | - Matthew J Robertson
- Department of Molecular and Cellular Biology, Baylor
College of Medicine, Houston, TX, USA
| | - Vasanta Putluri
- Advanced Technology Core, Alkek Center for Molecular
Discovery
| | - Nagireddy Putluri
- Department of Molecular and Cellular Biology, Baylor
College of Medicine, Houston, TX, USA
| | - Cristian Coarfa
- Department of Molecular and Cellular Biology, Baylor
College of Medicine, Houston, TX, USA
- Correspondence: Nancy L. Weigel and
Cristian Coarfa, Department of Molecular & Cellular Biology, Baylor College
of Medicine, Houston, TX 77030, USA. ,
| | - Nancy L Weigel
- Department of Molecular and Cellular Biology, Baylor
College of Medicine, Houston, TX, USA
- Correspondence: Nancy L. Weigel and
Cristian Coarfa, Department of Molecular & Cellular Biology, Baylor College
of Medicine, Houston, TX 77030, USA. ,
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Gatineau E, Arthur G, Poupeau A, Nichols K, Spear BT, Shelman NR, Graf GA, Temel RE, Yiannikouris FB. The prorenin receptor and its soluble form contribute to lipid homeostasis. Am J Physiol Endocrinol Metab 2021; 320:E609-E618. [PMID: 33459178 PMCID: PMC7988779 DOI: 10.1152/ajpendo.00135.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Obesity is associated with alterations in hepatic lipid metabolism. We previously identified the prorenin receptor (PRR) as a potential contributor to liver steatosis. Therefore, we aimed to determine the relative contribution of PRR and its soluble form, sPRR, to lipid homeostasis. PRR-floxed male mice were treated with an adeno-associated virus with thyroxine-binding globulin promoter-driven Cre to delete PRR in the liver [liver PRR knockout (KO) mice]. Hepatic PRR deletion did not change the body weight but increased liver weights. The deletion of PRR in the liver decreased peroxisome proliferator-activated receptor gamma (PPARγ) and triglyceride levels, but liver PRR KO mice exhibited higher plasma cholesterol levels and lower hepatic low-density lipoprotein receptor (LDLR) and Sortilin 1 (SORT1) proteins than control (CTL) mice. Surprisingly, hepatic PRR deletion elevated hepatic cholesterol, and up-regulated hepatic sterol regulatory element-binding protein 2 (SREBP2) and 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA-R) genes. In addition, the plasma levels of sPRR were significantly higher in liver PRR KO mice than in controls. In vitro studies in HepG2 cells demonstrated that sPRR treatment upregulated SREBP2, suggesting that sPRR could contribute to hepatic cholesterol biosynthesis. Interestingly, PRR, total cleaved and noncleaved sPRR contents, furin, and Site-1 protease (S1P) were elevated in the adipose tissue of liver PRR KO mice, suggesting that adipose tissue could contribute to the circulating pool of sPRR. Overall, this work supports previous works and opens a new area of investigation concerning the function of sPRR in lipid metabolism and adipose tissue-liver cross talk.NEW & NOTEWORTHY Hepatic PRR and its soluble form, sPRR, contribute to triglyceride and cholesterol homeostasis and hepatic inflammation. Deletion of hepatic PRR decreased triglyceride levels through a PRR-PPARγ-dependent mechanism but increased hepatic cholesterol synthesis through sPRR-medicated upregulation of SREBP-2. Our study highlighted a new paradigm of cross talk between the liver and the adipose tissue involving cholesterol and sPRR.
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Affiliation(s)
- Eva Gatineau
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Gertrude Arthur
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Audrey Poupeau
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Kellea Nichols
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, Kentucky
| | - Brett T Spear
- Department of Microbiology, Immunology and Molecular Genetics, University of Kentucky, Lexington, Kentucky
| | - Nathan R Shelman
- Department of Pathology & Laboratory Medicine, University of Kentucky, Lexington, Kentucky
| | - Gregory A Graf
- Department of Pharmaceutical Sciences, University of Kentucky, Lexington, Kentucky
| | - Ryan E Temel
- Cardiovascular Research Center and Department of Physiology, University of Kentucky, Lexington, Kentucky
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9
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Leonard CE, Baydyuk M, Stepler MA, Burton DA, Donoghue MJ. EphA7 isoforms differentially regulate cortical dendrite development. PLoS One 2020; 15:e0231561. [PMID: 33275600 PMCID: PMC7717530 DOI: 10.1371/journal.pone.0231561] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 11/22/2020] [Indexed: 02/06/2023] Open
Abstract
The shape of a neuron facilitates its functionality within neural circuits. Dendrites integrate incoming signals from axons, receiving excitatory input onto small protrusions called dendritic spines. Therefore, understanding dendritic growth and development is fundamental for discerning neural function. We previously demonstrated that EphA7 receptor signaling during cortical development impacts dendrites in two ways: EphA7 restricts dendritic growth early and promotes dendritic spine formation later. Here, the molecular basis for this shift in EphA7 function is defined. Expression analyses reveal that EphA7 full-length (EphA7-FL) and truncated (EphA7-T1; lacking kinase domain) isoforms are dynamically expressed in the developing cortex. Peak expression of EphA7-FL overlaps with dendritic elaboration around birth, while highest expression of EphA7-T1 coincides with dendritic spine formation in early postnatal life. Overexpression studies in cultured neurons demonstrate that EphA7-FL inhibits both dendritic growth and spine formation, while EphA7-T1 increases spine density. Furthermore, signaling downstream of EphA7 shifts during development, such that in vivo inhibition of mTOR by rapamycin in EphA7-mutant neurons ameliorates dendritic branching, but not dendritic spine phenotypes. Finally, direct interaction between EphA7-FL and EphA7-T1 is demonstrated in cultured cells, which results in reduction of EphA7-FL phosphorylation. In cortex, both isoforms are colocalized to synaptic fractions and both transcripts are expressed together within individual neurons, supporting a model where EphA7-T1 modulates EphA7-FL repulsive signaling during development. Thus, the divergent functions of EphA7 during cortical dendrite development are explained by the presence of two variants of the receptor.
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Affiliation(s)
- Carrie E. Leonard
- Department of Biology, Georgetown University, Washington, DC, United States of America
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States of America
| | - Maryna Baydyuk
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Marissa A. Stepler
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Denver A. Burton
- Department of Biology, Georgetown University, Washington, DC, United States of America
| | - Maria J. Donoghue
- Department of Biology, Georgetown University, Washington, DC, United States of America
- Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States of America
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Crosta CM, Hernandez K, Bhattiprolu AK, Fu AY, Moore JC, Clarke SG, Dudzinski NR, Brzustowicz LM, Paradiso KG, Firestein BL. Characterization hiPSC-derived neural progenitor cells and neurons to investigate the role of NOS1AP isoforms in human neuron dendritogenesis. Mol Cell Neurosci 2020; 109:103562. [PMID: 32987141 PMCID: PMC7736313 DOI: 10.1016/j.mcn.2020.103562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 09/02/2020] [Accepted: 09/22/2020] [Indexed: 01/30/2023] Open
Abstract
Abnormal dendritic arbor development has been implicated in a number of neurodevelopmental disorders, such as autism and Rett syndrome, and the neuropsychiatric disorder schizophrenia. Postmortem brain samples from subjects with schizophrenia show elevated levels of NOS1AP in the dorsolateral prefrontal cortex, a region of the brain associated with cognitive function. We previously reported that the long isoform of NOS1AP (NOS1AP-L), but not the short isoform (NOS1AP-S), negatively regulates dendrite branching in rat hippocampal neurons. To investigate the role that NOS1AP isoforms play in human dendritic arbor development, we adapted methods to generate human neural progenitor cells and neurons using induced pluripotent stem cell (iPSC) technology. We found that increased protein levels of either NOS1AP-L or NOS1AP-S decrease dendrite branching in human neurons at the developmental time point when primary and secondary branching actively occurs. Next, we tested whether pharmacological agents can decrease the expression of NOS1AP isoforms. Treatment of human iPSC-derived neurons with d-serine, but not clozapine, haloperidol, fluphenazine, or GLYX-13, results in a reduction in endogenous NOS1AP-L, but not NOS1AP-S, protein expression; however, d-serine treatment does not reverse decreases in dendrite number mediated by overexpression of NOS1AP isoforms. In summary, we demonstrate how an in vitro model of human neuronal development can help in understanding the etiology of schizophrenia and can also be used as a platform to screen drugs for patients.
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Affiliation(s)
- Christen M Crosta
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; Neurosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Kristina Hernandez
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA; Molecular Biosciences Graduate Program, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Atul K Bhattiprolu
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Allen Y Fu
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Jennifer C Moore
- Department of Genetics, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854-8082, USA
| | - Stephen G Clarke
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Natasha R Dudzinski
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Linda M Brzustowicz
- Department of Genetics, Rutgers, The State University of New Jersey, 604 Allison Road, Piscataway, NJ 08854-8082, USA
| | - Kenneth G Paradiso
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Bonnie L Firestein
- Department of Cell Biology and Neuroscience, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
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11
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Sogawa A, Takahashi I, Kyo M, Imaizumi-Anraku H, Tajima S, Nomura M. Requirements of Qa-SNARE LjSYP132s for Nodulation and Seed Development in Lotus japonicus. Plant Cell Physiol 2020; 61:1750-1759. [PMID: 32706881 DOI: 10.1093/pcp/pcaa099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 07/16/2020] [Indexed: 06/11/2023]
Abstract
SNAREs (soluble N-ethyl maleimide-sensitive factor attachment protein receptors) mediate membrane fusion of vesicle transport in eukaryotic cells. LjSYP132s are the members of Qa-SNAREs in Lotus japonicus. Two isoforms, LjSYP132a and LjSYP132b, are generated by alternative splicing. Immunoblot analysis detected strong expression of LjSYP132s in infected root nodules and seeds by posttranscriptional modification. In either LjSYP132a or LjSYP132b silenced roots (RNAi-LjSYP132a, RNAi-LjSYP132b), the infection thread (IT) was not elongated, suggesting that both LjSYP132a and LjSYP132b have a role in IT progression. The results were consistent with the data of qRT-PCR showing that both genes were expressed at the early stage of infection. However, during the nodulation, only LjSYP132a was induced. LjSYP132s protein was observed in the Mesorhizobium loti-inoculated roots of mutants, nfr1, castor and pollux, suggesting that LjSYP132s can be induced without Nod factor signaling. Accumulation of LjSYP132s in the peribacteroid membrane suggests the function of not only IT formation but also nutrient transport. In contrast, qRT-PCR showed that LjSYP132b was expressed in the seeds. A stable transgenic plant of LjSYP132b, R132b, was produced by RNAi silencing. In the R132b plants, small pods with a few seeds and abnormal tip growth of the pollen tubes were observed, suggesting that LjSYP132b has a role in pollen tube growth and nutrient transport in the plasma membrane of seeds.
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Affiliation(s)
- Aoi Sogawa
- Faculty of Agriculture, Kagawa University, Miki, Kita, Kagawa, 761-0795 Japan
| | - Issei Takahashi
- Faculty of Agriculture, Kagawa University, Miki, Kita, Kagawa, 761-0795 Japan
| | - Masaharu Kyo
- Faculty of Agriculture, Kagawa University, Miki, Kita, Kagawa, 761-0795 Japan
| | - Haruko Imaizumi-Anraku
- Institute of Agrobiological Sciences, NARO, 3-1-3 Kannon-dai, Tsukuba, Ibaraki, 305-8604 Japan
| | - Shigeyuki Tajima
- Faculty of Agriculture, Kagawa University, Miki, Kita, Kagawa, 761-0795 Japan
| | - Mika Nomura
- Faculty of Agriculture, Kagawa University, Miki, Kita, Kagawa, 761-0795 Japan
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12
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Yin J, Reiman EM, Beach TG, Serrano GE, Sabbagh MN, Nielsen M, Caselli RJ, Shi J. Effect of ApoE isoforms on mitochondria in Alzheimer disease. Neurology 2020; 94:e2404-e2411. [PMID: 32457210 PMCID: PMC7455369 DOI: 10.1212/wnl.0000000000009582] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 12/26/2019] [Indexed: 01/25/2023] Open
Abstract
OBJECTIVE To test the hypothesis that ApoE isoforms affect mitochondrial structure and function that are related to cognitive impairment in Alzheimer disease (AD), we systematically investigated the effects of ApoE isoforms on mitochondrial biogenesis and dynamics, oxidative stress, synapses, and cognitive performance in AD. METHODS We obtained postmortem human brain tissues and measured proteins that are responsible for mitochondrial biogenesis (peroxisome proliferator-activated receptor-gamma coactivator-1α [PGC-1α] and sirtuin 3 [SIRT3]), for mitochondrial dynamics (mitofusin 1 [MFN1], mitofusin 2 [MFN2], and dynamin-like protein 1 [DLP1]), for oxidative stress (superoxide dismutase 2 [SOD2] and forkhead-box protein O3a [Foxo3a]), and for synapses (postsynaptic density protein 95 [PSD95] and synapsin1 [Syn1]). A total of 46 cases were enrolled, including ApoE-ɛ4 carriers (n = 21) and noncarriers (n = 25). RESULTS Levels of these proteins were compared between ApoE-ɛ4 carriers and noncarriers. ApoE-ɛ4 was associated with impaired mitochondrial structure and function, oxidative stress, and synaptic integrity in the human brain. Correlation analysis revealed that mitochondrial proteins and the synaptic protein were strongly associated with cognitive performance. CONCLUSION ApoE isoforms influence mitochondrial structure and function, which likely leads to alteration in oxidative stress, synapses, and cognitive function. These mitochondria-related proteins may be a harbinger of cognitive decline in ApoE-ɛ4 carriers and provide novel therapeutic targets for prevention and treatment of AD.
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Affiliation(s)
- Junxiang Yin
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing
| | - Eric M Reiman
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing
| | - Thomas G Beach
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing
| | - Geidy E Serrano
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing
| | - Marwan N Sabbagh
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing
| | - Megan Nielsen
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing
| | - Richard J Caselli
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing
| | - Jiong Shi
- From the Barrow Neurological Institute (J.Y., M.N.S., M.N., J.S.), St. Joseph Hospital and Medical Center, Phoenix, AZ; Banner Alzheimer's Institute (E.M.R.), Phoenix, AZ; Civin Laboratory for Neuropathology (T.G.B., G.E.S.), Banner Sun Health Research Institute, Sun City, AZ; Cleveland Clinic Lou Ruvo Center for Brain Health (M.N.S.), Las Vegas, NV; School of Life Sciences (M.N.), Arizona State University, Tempe; Department of Neurology (R.J.C.), Mayo Clinic Arizona, Scottsdale; Advanced Innovation Center for Human Brain Protection (J.S.), Capital Medical University, Beijing, China; and China National Clinical Research Center for Neurological Diseases (J.S.), Beijing Tiantan Hospital, Capital Medical University, Beijing.
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13
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Kwon Y, Jeon YW, Kwon M, Cho Y, Park D, Shin JE. βPix-d promotes tubulin acetylation and neurite outgrowth through a PAK/Stathmin1 signaling pathway. PLoS One 2020; 15:e0230814. [PMID: 32251425 PMCID: PMC7135283 DOI: 10.1371/journal.pone.0230814] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 03/09/2020] [Indexed: 12/11/2022] Open
Abstract
Microtubules are a major cytoskeletal component of neurites, and the regulation of microtubule stability is essential for neurite morphogenesis. βPix (ARHGEF7) is a guanine nucleotide exchange factor for the small GTPases Rac1 and Cdc42, which modulate the organization of actin filaments and microtubules. βPix is expressed as alternatively spliced variants, including the ubiquitous isoform βPix-a and the neuronal isoforms βPix-b and βPix-d, but the function of the neuronal isoforms remains unclear. Here, we reveal the novel role of βPix neuronal isoforms in regulating tubulin acetylation and neurite outgrowth. At DIV4, hippocampal neurons cultured from βPix neuronal isoform knockout (βPix-NIKO) mice exhibit defects in neurite morphology and tubulin acetylation, a type of tubulin modification which often labels stable microtubules. Treating βPix-NIKO neurons with paclitaxel, which stabilizes the microtubules, or reintroducing either neuronal βPix isoform to the KO neurons overcomes the impairment in neurite morphology and tubulin acetylation, suggesting that neuronal βPix isoforms may promote microtubule stabilization during neurite development. βPix-NIKO neurons also exhibit lower phosphorylation levels for Stathmin1, a microtubule-destabilizing protein, at Ser16. Expressing either βPix neuronal isoform in the βPix-NIKO neurons restores Stathmin1 phosphorylation levels, with βPix-d having a greater effect than βPix-b. Furthermore, we find that the recovery of neurite length and Stathmin1 phosphorylation via βPix-d expression requires PAK kinase activity. Taken together, our study demonstrates that βPix-d regulates the phosphorylation of Stathmin1 in a PAK-dependent manner and that neuronal βPix isoforms promote tubulin acetylation and neurite morphogenesis during neuronal development.
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Affiliation(s)
- Younghee Kwon
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Ye Won Jeon
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Minjae Kwon
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Yongcheol Cho
- Division of Life Sciences, College of Life Sciences and Biotechnology, Korea University, Seoul, Republic of Korea
| | - Dongeun Park
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jung Eun Shin
- School of Biological Sciences, Seoul National University, Seoul, Republic of Korea
- Institute of Life Science and Biotechnology, Korea University, Seoul, Republic of Korea
- * E-mail:
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14
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Mason ER, Cummins TR. Differential Inhibition of Human Nav1.2 Resurgent and Persistent Sodium Currents by Cannabidiol and GS967. Int J Mol Sci 2020; 21:ijms21072454. [PMID: 32244818 PMCID: PMC7177867 DOI: 10.3390/ijms21072454] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/27/2020] [Accepted: 03/28/2020] [Indexed: 12/24/2022] Open
Abstract
Many epilepsy patients are refractory to conventional antiepileptic drugs. Resurgent and persistent currents can be enhanced by epilepsy mutations in the Nav1.2 channel, but conventional antiepileptic drugs inhibit normal transient currents through these channels, along with aberrant resurgent and persistent currents that are enhanced by Nav1.2 epilepsy mutations. Pharmacotherapies that specifically target aberrant resurgent and/or persistent currents would likely have fewer unwanted side effects and be effective in many patients with refractory epilepsy. This study investigated the effects of cannbidiol (CBD) and GS967 (each at 1 μM) on transient, resurgent, and persistent currents in human embryonic kidney (HEK) cells stably expressing wild-type hNav1.2 channels. We found that CBD preferentially inhibits resurgent currents over transient currents in this paradigm; and that GS967 preferentially inhibits persistent currents over transient currents. Therefore, CBD and GS967 may represent a new class of more targeted and effective antiepileptic drugs.
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Affiliation(s)
- Emily R. Mason
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, IUPUI campus, Indianapolis, IN 46202, USA
- Correspondence:
| | - Theodore R. Cummins
- Department of Biology, Purdue School of Science, IUPUI campus, Indianapolis, IN 46202, USA;
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15
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Ishii H, Hattori Y, Ozawa H. Identification of a novel C-terminally truncated estrogen receptor α variant (ERαi34) with constitutive transactivation and estrogen receptor antagonist resistance. Mol Cell Endocrinol 2020; 503:110693. [PMID: 31881246 DOI: 10.1016/j.mce.2019.110693] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 12/07/2019] [Accepted: 12/23/2019] [Indexed: 11/20/2022]
Abstract
Constitutively active estrogen receptor α (ERα) variants with C-terminal truncation are candidate molecules for gain of both endocrine- and chemotherapy-resistance in estrogen-sensitive tumors. Our previous reports using artificially truncated ERα constructs demonstrated that ERα variants encoded in 1-2-3-cryptic exon- and 1-2-3-4-cryptic exon-types of transcripts have potentials to display constitutive transactivation of an estrogen response element reporter. However, naturally occurring 1-2-3-cryptic exon-type ERα variants have not been cloned yet. Therefore, the present study was designed to identify naturally occurring ERα variants encoded in 1-2-3-cryptic exon-type ERα transcripts. We cloned a novel C-terminally truncated ERα variant (ERαi34) encoded in a 1-2-3-i34 transcript from MCF-7 cells and characterized its constitutive and ER antagonist-resistant transactivation in transfected cells. Stable transfection of the variant into MCF-7 cells augmented basal cell proliferation insensitive to fulvestrant. Collectively, we validated the structure-based mechanisms underlying constitutive and ER antagonist-resistant transactivation by C-terminally truncated ERα variants.
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Affiliation(s)
- Hirotaka Ishii
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8602, Japan.
| | - Yujiro Hattori
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8602, Japan.
| | - Hitoshi Ozawa
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo, 113-8602, Japan.
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16
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Pan Y, Ballance H, Meng H, Gonzalez N, Kim SM, Abdurehman L, York B, Chen X, Schnytzer Y, Levy O, Dacso CC, McClung CA, O’Malley BW, Liu S, Zhu B. 12-h clock regulation of genetic information flow by XBP1s. PLoS Biol 2020; 18:e3000580. [PMID: 31935211 PMCID: PMC6959563 DOI: 10.1371/journal.pbio.3000580] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 12/11/2019] [Indexed: 12/15/2022] Open
Abstract
Our group recently characterized a cell-autonomous mammalian 12-h clock independent from the circadian clock, but its function and mechanism of regulation remain poorly understood. Here, we show that in mouse liver, transcriptional regulation significantly contributes to the establishment of 12-h rhythms of mRNA expression in a manner dependent on Spliced Form of X-box Binding Protein 1 (XBP1s). Mechanistically, the motif stringency of XBP1s promoter binding sites dictates XBP1s’s ability to drive 12-h rhythms of nascent mRNA transcription at dawn and dusk, which are enriched for basal transcription regulation, mRNA processing and export, ribosome biogenesis, translation initiation, and protein processing/sorting in the Endoplasmic Reticulum (ER)-Golgi in a temporal order consistent with the progressive molecular processing sequence described by the central dogma information flow (CEDIF). We further identified GA-binding proteins (GABPs) as putative novel transcriptional regulators driving 12-h rhythms of gene expression with more diverse phases. These 12-h rhythms of gene expression are cell autonomous and evolutionarily conserved in marine animals possessing a circatidal clock. Our results demonstrate an evolutionarily conserved, intricate network of transcriptional control of the mammalian 12-h clock that mediates diverse biological pathways. We speculate that the 12-h clock is coopted to accommodate elevated gene expression and processing in mammals at the two rush hours, with the particular genes processed at each rush hour regulated by the circadian and/or tissue-specific pathways. Distinct from the well-known 24-hour circadian clock, this study shows that the mammalian 12-hour clock upregulates genetic information flow capacity during the two "rush hours" (dawn and dusk) in a manner dependent on the transcription factor XBP1s.
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Affiliation(s)
- Yinghong Pan
- UPMC Genome Center, Pittsburgh, Pennsylvania, United States of America
| | - Heather Ballance
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Huan Meng
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Naomi Gonzalez
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Sam-Moon Kim
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Leymaan Abdurehman
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Brian York
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Xi Chen
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Yisrael Schnytzer
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Oren Levy
- The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel
| | - Clifford C. Dacso
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Colleen A. McClung
- Translational Neuroscience Program, Department of Psychiatry, Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Bert W. O’Malley
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Silvia Liu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pennsylvania, United States of America
- * E-mail: (SL); (BZ)
| | - Bokai Zhu
- Aging Institute of UPMC, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pennsylvania, United States of America
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (SL); (BZ)
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17
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Lee S, Joung YH, Kim JK, Do Choi Y, Jang G. An isoform of the plastid RNA polymerase-associated protein FSD3 negatively regulates chloroplast development. BMC Plant Biol 2019; 19:524. [PMID: 31775615 PMCID: PMC6882211 DOI: 10.1186/s12870-019-2128-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Accepted: 11/08/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Plastid-encoded RNA polymerase (PEP) plays an essential role in chloroplast development by governing the expression of genes involved in photosynthesis. At least 12 PEP-associated proteins (PAPs), including FSD3/PAP4, regulate PEP activity and chloroplast development by modulating formation of the PEP complex. RESULTS In this study, we identified FSD3S, a splicing variant of FSD3; the FSD3 and FSD3S transcripts encode proteins with identical N-termini, but different C-termini. Characterization of FSD3 and FSD3S proteins showed that the C-terminal region of FSD3S contains a transmembrane domain, which promotes FSD3S localization to the chloroplast membrane but not to nucleoids, in contrast to FSD3, which localizes to the chloroplast nucleoid. We also found that overexpression of FSD3S negatively affects photosynthetic activity and chloroplast development by reducing expression of genes involved in photosynthesis. In addition, FSD3S failed to complement the chloroplast developmental defects in the fsd3 mutant. CONCLUSION These results suggest FSD3 and FSD3S, with their distinct localization patterns, have different functions in chloroplast development, and FSD3S negatively regulates expression of PEP-dependent chloroplast genes, and development of chloroplasts.
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Affiliation(s)
- Sangyool Lee
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186 Republic of Korea
| | - Young Hee Joung
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186 Republic of Korea
| | - Ju-Kon Kim
- Graduate School of International Agricultural Technology and Crop Biotechnology Institute/Green BioScience and Technology, Seoul National University, Pyeongchang, 25354 Republic of Korea
| | - Yang Do Choi
- Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, 08826 Republic of Korea
- The National Academy of Sciences, Seoul, 06579 Republic of Korea
| | - Geupil Jang
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, 61186 Republic of Korea
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18
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Sulzer D, Edwards RH. The physiological role of α-synuclein and its relationship to Parkinson's Disease. J Neurochem 2019; 150:475-486. [PMID: 31269263 PMCID: PMC6707892 DOI: 10.1111/jnc.14810] [Citation(s) in RCA: 185] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 06/03/2019] [Accepted: 06/28/2019] [Indexed: 12/15/2022]
Abstract
The protein α-synuclein has a central role in the pathogenesis of Parkinson's disease (PD). In this review, we discuss recent results concerning its primary function, which appears to be on cell membranes. The pre-synaptic location of synuclein has suggested a role in neurotransmitter release and it apparently associates with synaptic vesicles because of their high curvature. Indeed, synuclein over-expression inhibits synaptic vesicle exocytosis. However, loss of synuclein has not yet been shown to have a major effect on synaptic transmission. Consistent with work showing that synuclein can promote as well as sense membrane curvature, recent analysis of synuclein triple knockout mice now shows that synuclein accelerates dilation of the exocytic fusion pore. This form of regulation affects primarily the release of slowly discharged lumenal cargo such as neural peptides, but presumably also contributes to maintenance of the release site. This article is part of the Special Issue "Synuclein".
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Affiliation(s)
- David Sulzer
- Departments of Psychiatry, Neurology and Pharmacology, Columbia University Medical Center, New York State Psychiatric Institute
| | - Robert H Edwards
- Departments of Neurology and Physiology, Graduate Programs in Cell Biology, Biomedical Sciences and Neuroscience, UCSF School of Medicine
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19
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Rice GR, Barmina O, Luecke D, Hu K, Arbeitman M, Kopp A. Modular tissue-specific regulation of doublesex underpins sexually dimorphic development in Drosophila. Development 2019; 146:dev178285. [PMID: 31285355 PMCID: PMC6679366 DOI: 10.1242/dev.178285] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 06/28/2019] [Indexed: 11/20/2022]
Abstract
The ability of a single genome to produce distinct and often dramatically different male and female forms is one of the wonders of animal development. In Drosophila melanogaster, most sexually dimorphic traits are controlled by sex-specific isoforms of the doublesex (dsx) transcription factor, and dsx expression is mostly limited to cells that give rise to sexually dimorphic traits. However, it is unknown how this mosaic of sexually dimorphic and monomorphic organs arises. Here, we characterize the cis-regulatory sequences that control dsx expression in the foreleg, which contains multiple types of sex-specific sensory organs. We find that separate modular enhancers are responsible for dsx expression in each sexually dimorphic organ. Expression of dsx in the sex comb is co-regulated by two enhancers with distinct spatial and temporal specificities that are separated by a genitalia-specific enhancer. The sex comb-specific enhancer from D. willistoni, a species that primitively lacks sex combs, is not active in the foreleg. Thus, the mosaic of sexually dimorphic and monomorphic organs depends on modular regulation of dsx transcription by dedicated cell type-specific enhancers.
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Affiliation(s)
- Gavin R Rice
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Olga Barmina
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - David Luecke
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - Kevin Hu
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
| | - Michelle Arbeitman
- Department of Biomedical Sciences, Florida State University, Tallahassee, FL 32306, USA
| | - Artyom Kopp
- Department of Evolution and Ecology, University of California-Davis, Davis, CA 95616, USA
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20
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Albaqami M, Laluk K, Reddy ASN. The Arabidopsis splicing regulator SR45 confers salt tolerance in a splice isoform-dependent manner. Plant Mol Biol 2019; 100:379-390. [PMID: 30968308 DOI: 10.1007/s11103-019-00864-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 03/28/2019] [Indexed: 05/08/2023]
Abstract
Functions of most splice isoforms that are generated by alternative splicing are unknown. We show that two splice variants that encode proteins differing in only eight amino acids have distinct functions in a stress response. Serine/arginine-rich (SR) and SR-like proteins, a conserved family of RNA binding proteins across eukaryotes, play important roles in pre-mRNA splicing and other post-transcriptional processes. Pre-mRNAs of SR and SR-like proteins undergo extensive alternative splicing in response to diverse stresses and produce multiple splice isoforms. However, the functions of most splice isoforms remain elusive. Alternative splicing of pre-mRNA of Arabidopsis SR45, which encodes an SR-like splicing regulator, generates two isoforms (long-SR45.1 and short-SR45.2). The proteins encoded by these two isoforms differ in eight amino acids. Here, we investigated the role of SR45 and its splice variants in salt stress tolerance. The loss of SR45 resulted in enhanced sensitivity to salt stress and changes in expression and splicing of genes involved in regulating salt stress response. Interestingly, only the long isoform (SR45.1) rescued the salt-sensitive phenotype as well as the altered gene expression and splicing patterns in the mutant. These results suggest that SR45 positively regulates salt tolerance. Furthermore, only the long isoform is required for SR45-mediated salt tolerance.
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Affiliation(s)
- Mohammed Albaqami
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA
- Department of Biology, Faculty of Applied Science, Umm Al-Qura University, Mecca, 21955, Kingdom of Saudi Arabia
| | - K Laluk
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Anireddy S N Reddy
- Department of Biology and Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO, 80523, USA.
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21
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Chen W, Taylor MC, Barrow RA, Croyal M, Masle J. Loss of Phosphoethanolamine N-Methyltransferases Abolishes Phosphatidylcholine Synthesis and Is Lethal. Plant Physiol 2019; 179:124-142. [PMID: 30381317 PMCID: PMC6324220 DOI: 10.1104/pp.18.00694] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/19/2018] [Indexed: 05/21/2023]
Abstract
Plants use several pathways to synthesize phosphatidylcholine (PC), the major phospholipid of eukaryotic cells. PC has important structural and signaling roles. One pathway plants use for synthesis is the phospho-base methylation pathway, which forms the head-group phosphocholine through the triple methylation of phosphoethanolamine (PEA) catalyzed by phosphoethanolamine N-methyltransferases (PEAMTs). Our understanding of that pathway and its physiological importance remains limited. We recently reported that disruption of Arabidopsis thaliana PEAMT1/NMT1 and PEAMT3/NMT3 induces severe PC deficiency leading to dwarfism and impaired development. However, the double nmt1 nmt3 knock-out mutant is viable. Here, we show that this is enabled by residual PEAMT activity through a third family member, NMT2. The triple nmt1 nmt2 nmt3 knock-out mutant cannot synthesize PC from PEA and is lethal. This shows that, unlike mammals and yeast, Arabidopsis cannot form PC from phosphatidyl ethanolamine (PE), and demonstrates that methylation of PEA is the sole, and vital, entry point to PC synthesis. We further show that Arabidopsis has evolved an expanded family of four nonredundant PEAMTs through gene duplication and alternate use of the NMT2 promoter. NMT2 encodes two PEAMT variants, which greatly differ in their ability to perform the initial phospho-base methylation of PEA. Five amino acids at the N terminus of PEAMTs are shown to each be critical for the catalysis of that step committing to PC synthesis. As a whole, these findings open new avenues for enzymatic engineering and the exploration of ways to better tune phosphocholine and PC synthesis to environmental conditions for improved plant performance.
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Affiliation(s)
- Weihua Chen
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Matthew C Taylor
- Land and Water Flagship, Commonwealth Scientific and Industrial Research Organization, Canberra, Australian Capital Territory 2601, Australia
| | - Russell A Barrow
- Research School of Chemistry, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
| | - Mikaël Croyal
- CRNH Nantes, Mass Spectrometry Core facility, 8 Quai Moncousu BP-70721, Nantes cedex 1, France
| | - Josette Masle
- Research School of Biology, The Australian National University, Canberra, Australian Capital Territory 2601, Australia
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22
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Abstract
Cell migration requires a complicated network of structural and regulatory proteins. Changes in cellular motility can impact migration as a result of cell-type or developmental stage regulated expression of critical motility genes. Hnrnpab is a conserved RNA-binding protein found as two isoforms produced by alternative splicing. Its expression is enriched in the subventricular zone (SVZ) and the rostral migratory stream within the brain, suggesting possible support of the migration of neural progenitor cells in this region. Here we show that the migration of cells from the SVZ of developing Hnrnpab-/- mouse brains is impaired. An RNA-seq analysis to identify Hnrnpab-dependent cell motility genes led us to Eps8, and in agreement with the change in cell motility, we show that Eps8 is decreased in Hnrnpab-/- SVZ tissue. We scrutinized the motility of Hnrnpab-/- cells and confirmed that the decreases in both cell motility and Eps8 are restored by ectopically coexpressing both alternatively spliced Hnrnpab isoforms, therefore these variants are surprisingly nonredundant for cell motility. Our results support a model where both Hnrnpab isoforms work in concert to regulate Eps8 transcription in the mouse SVZ to promote the normal migration of neural cells during CNS development.
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Affiliation(s)
- Alexa A Lampasona
- Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York 11749, USA
- Centers for Molecular Medicine, Stony Brook University, Stony Brook, New York 11749, USA
| | - Kevin Czaplinski
- Centers for Molecular Medicine, Stony Brook University, Stony Brook, New York 11749, USA
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11749, USA
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23
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Greathouse KM, Boros BD, Deslauriers JF, Henderson BW, Curtis KA, Gentry EG, Herskowitz JH. Distinct and complementary functions of rho kinase isoforms ROCK1 and ROCK2 in prefrontal cortex structural plasticity. Brain Struct Funct 2018; 223:4227-4241. [PMID: 30196430 PMCID: PMC6252131 DOI: 10.1007/s00429-018-1748-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 09/04/2018] [Indexed: 12/13/2022]
Abstract
Rho-associated protein kinases (ROCK) 1 and 2 are attractive drug targets for a range of neurologic disorders; however, a critical barrier to ROCK-based therapeutics is ambiguity over whether there are isoform-specific roles for ROCKs in neuronal structural plasticity. Here, we used a genetics approach to address this long-standing question by analyzing both male and female adult ROCK1+/- and ROCK2+/- mice compared to littermate controls. Individual pyramidal neurons in the medial prefrontal cortex (mPFC) were targeted for iontophoretic microinjection of fluorescent dye, followed by high-resolution confocal microscopy and neuronal 3D reconstructions for morphometry analysis. Increased apical and basal dendritic length and intersections were observed in ROCK1+/- but not ROCK2+/- mice. Although dendritic spine densities were comparable among genotypes, apical spine length was decreased in ROCK1+/- but increased in ROCK2+/- mice. Spine head and neck diameter were reduced similarly in ROCK1+/- and ROCK2+/- mice; however, certain spine morphologic subclasses were more affected than others in a genotype-dependent manner. Biochemical analyses of ROCK substrates in synaptic fractions revealed that phosphorylation of LIM kinase and cofilin were reduced in ROCK1+/- and ROCK2+/- mice, while phosphorylation of myosin light chain was decreased exclusively in ROCK1+/- mice. Collectively, these observations implicate ROCK1 as a novel regulatory factor of neuronal dendritic structure and detail distinct and complementary roles of ROCKs in mPFC dendritic spine structure.
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Affiliation(s)
- Kelsey M Greathouse
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL, 35294, USA
| | - Benjamin D Boros
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL, 35294, USA
| | - Josue F Deslauriers
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL, 35294, USA
| | - Benjamin W Henderson
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL, 35294, USA
| | - Kendall A Curtis
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL, 35294, USA
| | - Erik G Gentry
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL, 35294, USA
| | - Jeremy H Herskowitz
- Department of Neurology, Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, 1825 University Blvd., Birmingham, AL, 35294, USA.
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24
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Rosales-Vega M, Hernández-Becerril A, Murillo-Maldonado JM, Zurita M, Vázquez M. The role of the trithorax group TnaA isoforms in Hox gene expression, and in Drosophila late development. PLoS One 2018; 13:e0206587. [PMID: 30372466 PMCID: PMC6205608 DOI: 10.1371/journal.pone.0206587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 10/16/2018] [Indexed: 11/18/2022] Open
Abstract
Regulation of developmental gene expression in eukaryotes involves several levels. One of them is the maintenance of gene expression along the life of the animal once it is started by different triggers early in development. One of the questions in the field is when in developmental time, the animal start to use the different maintenance mechanisms. The trithorax group (TrxG) of genes was first characterized as essential for maintaining homeotic gene expression. The TrxG gene tonalli interacts genetically and physically with genes and subunits of the BRAHMA BAP chromatin remodeling complex and encodes TnaA proteins with putative E3 SUMO-ligase activity. In contrast to the phenocritic lethal phase of animals with mutations in other TrxG genes, tna mutant individuals die late in development. In this study we determined the requirements of TnaA for survival at pupal and adult stages, in different tna mutant genotypes where we corroborate the lack of TnaA proteins, and the presence of adult homeotic loss-of-function phenotypes. We also investigated whether the absence of TnaA in haltere and leg larval imaginal discs affects the presence of the homeotic proteins Ultrabithorax and Sex combs reduced respectively by using some of the characterized genotypes and more finely by generating TnaA defective clones induced at different stages of development. We found that, tna is not required for growth or survival of imaginal disc cells and that it is a fine modulator of homeotic gene expression.
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Affiliation(s)
- Marco Rosales-Vega
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Adriana Hernández-Becerril
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Juan Manuel Murillo-Maldonado
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, Querétaro, México
| | - Mario Zurita
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Martha Vázquez
- Departamento de Fisiología Molecular y Genética del Desarrollo, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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25
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Fekry B, Ribas-Latre A, Baumgartner C, Deans JR, Kwok C, Patel P, Fu L, Berdeaux R, Sun K, Kolonin MG, Wang SH, Yoo SH, Sladek FM, Eckel-Mahan K. Incompatibility of the circadian protein BMAL1 and HNF4α in hepatocellular carcinoma. Nat Commun 2018; 9:4349. [PMID: 30341289 PMCID: PMC6195513 DOI: 10.1038/s41467-018-06648-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 09/18/2018] [Indexed: 02/07/2023] Open
Abstract
Hepatocyte nuclear factor 4 alpha (HNF4α) is a master regulator of liver-specific gene expression with potent tumor suppressor activity, yet many liver tumors express HNF4α. This study reveals that P1-HNF4α, the predominant isoform expressed in the adult liver, inhibits expression of tumor promoting genes in a circadian manner. In contrast, an additional isoform of HNF4α, driven by an alternative promoter (P2-HNF4α), is induced in HNF4α-positive human hepatocellular carcinoma (HCC). P2-HNF4α represses the circadian clock gene ARNTL (BMAL1), which is robustly expressed in healthy hepatocytes, and causes nuclear to cytoplasmic re-localization of P1-HNF4α. We reveal mechanisms underlying the incompatibility of BMAL1 and P2-HNF4α in HCC, and demonstrate that forced expression of BMAL1 in HNF4α-positive HCC prevents the growth of tumors in vivo. These data suggest that manipulation of the circadian clock in HNF4α-positive HCC could be a tractable strategy to inhibit tumor growth and progression in the liver.
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Affiliation(s)
- Baharan Fekry
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Aleix Ribas-Latre
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Corrine Baumgartner
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Jonathan R Deans
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, 92521, USA
| | - Christopher Kwok
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Pooja Patel
- Department of Pediatrics, Molecular and Cellular Biology, Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Loning Fu
- Department of Pediatrics, Molecular and Cellular Biology, Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Rebecca Berdeaux
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Kai Sun
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
- Department of Biochemistry and Molecular Biology, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Mikhail G Kolonin
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Sidney H Wang
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Seung-Hee Yoo
- Department of Biochemistry and Molecular Biology, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA
| | - Frances M Sladek
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, CA, 92521, USA
| | - Kristin Eckel-Mahan
- Institute of Molecular Medicine, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA.
- Department of Biochemistry and Molecular Biology, McGovern Medical School at the University of Texas Health Science Center (UT Health), Houston, TX, 77030, USA.
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26
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Waller SJ, Knighton LE, Crabtree LM, Perkins AL, Reitzel AM, Truman AW. Characterizing functional differences in sea anemone Hsp70 isoforms using budding yeast. Cell Stress Chaperones 2018; 23:933-941. [PMID: 29696514 PMCID: PMC6111083 DOI: 10.1007/s12192-018-0900-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 04/12/2018] [Accepted: 04/16/2018] [Indexed: 12/19/2022] Open
Abstract
Marine organisms experience abiotic stressors such as fluctuations in temperature, UV radiation, salinity, and oxygen concentration. Heat shock proteins (HSPs) assist in the response of cells to these stressors by refolding and maintaining the activity of damaged proteins. The well-conserved Hsp70 chaperone family is essential for cell viability as well as the response to stress. Organisms possess a variety of Hsp70 isoforms that differ slightly in amino acid sequence, yet very little is known about their functional relevance. In this study, we undertook analysis of three principal Hsp70 isoforms NvHsp70A, B, and D from the starlet sea anemone Nematostella vectensis. The functionality of Hsp70 isoforms in the starlet sea anemone was assessed through transcriptional analysis and by heterologous expression in budding yeast Saccharomyces cerevisiae. Interestingly, these isoforms were found to not only differ in expression under stress but also appear to have functional differences in their ability to mediate the cellular stress program. These results contribute to an understanding of Hsp70 isoform specificity, their shared and unique roles in response to acute and chronic environmental stress, and the potential basis of local adaptation in populations of N. vectensis.
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Affiliation(s)
- Shawn J Waller
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Laura E Knighton
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Lenora M Crabtree
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Abigail L Perkins
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Adam M Reitzel
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Andrew W Truman
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, 28223, USA.
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27
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Peigneur S, Paiva ALB, Cordeiro MN, Borges MH, Diniz MRV, de Lima ME, Tytgat J. Phoneutria nigriventer Spider Toxin PnTx2-1 (δ-Ctenitoxin-Pn1a) Is a Modulator of Sodium Channel Gating. Toxins (Basel) 2018; 10:toxins10090337. [PMID: 30134593 PMCID: PMC6162791 DOI: 10.3390/toxins10090337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 08/15/2018] [Accepted: 08/16/2018] [Indexed: 01/31/2023] Open
Abstract
Spider venoms are complex mixtures of biologically active components with potentially interesting applications for drug discovery or for agricultural purposes. The spider Phoneutria nigriventer is responsible for a number of envenomations with sometimes severe clinical manifestations in humans. A more efficient treatment requires a comprehensive knowledge of the venom composition and of the action mechanism of the constituting components. PnTx2-1 (also called δ-ctenitoxin-Pn1a) is a 53-amino-acid-residue peptide isolated from the venom fraction PhTx2. Although PnTx2-1 is classified as a neurotoxin, its molecular target has remained unknown. This study describes the electrophysiological characterization of PnTx2-1 as a modulator of voltage-gated sodium channels. PnTx2-1 is investigated for its activity on seven mammalian NaV-channel isoforms, one insect NaV channel and one arachnid NaV channel. Furthermore, comparison of the activity of both PnTx2-1 and PnTx2-6 on NaV1.5 channels reveals that this family of Phoneutria toxins modulates the cardiac NaV channel in a bifunctional manner, resulting in an alteration of the inactivation process and a reduction of the sodium peak current.
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Affiliation(s)
- Steve Peigneur
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, P.O. Box 922, Herestraat 49, 3000 Leuven, Belgium.
- Laboratório de Venenos e Toxinas Animais, Dept de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil.
| | - Ana Luiza B Paiva
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Minas Gerais, Belo Horizonte 30510-010, Brazil.
| | - Marta N Cordeiro
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Minas Gerais, Belo Horizonte 30510-010, Brazil.
| | - Márcia H Borges
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Minas Gerais, Belo Horizonte 30510-010, Brazil.
| | - Marcelo R V Diniz
- Departamento de Pesquisa e Desenvolvimento, Fundação Ezequiel Dias, Minas Gerais, Belo Horizonte 30510-010, Brazil.
| | - Maria Elena de Lima
- Laboratório de Venenos e Toxinas Animais, Dept de Bioquímica e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte 31270-901, Brazil.
- Programa de Pós-graduação em Ciências da Saúde, Biomedicina e Medicina, Instituto de Ensino e Pesquisa da Santa Casa de Belo Horizonte, Grupo Santa Casa de Belo Horizonte, Minas Gerais, Belo Horizonte 31270-901, Brazil.
| | - Jan Tytgat
- Toxicology and Pharmacology, University of Leuven (KU Leuven), Campus Gasthuisberg, P.O. Box 922, Herestraat 49, 3000 Leuven, Belgium.
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28
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Barnes DE, Watabe E, Ono K, Kwak E, Kuroyanagi H, Ono S. Tropomyosin isoforms differentially affect muscle contractility in the head and body regions of the nematode Caenorhabditis elegans. Mol Biol Cell 2018; 29:1075-1088. [PMID: 29496965 PMCID: PMC5921574 DOI: 10.1091/mbc.e17-03-0152] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 02/21/2018] [Accepted: 02/23/2018] [Indexed: 11/11/2022] Open
Abstract
Tropomyosin, one of the major actin filament-binding proteins, regulates actin-myosin interaction and actin-filament stability. Multicellular organisms express a number of tropomyosin isoforms, but understanding of isoform-specific tropomyosin functions is incomplete. The nematode Caenorhabditis elegans has a single tropomyosin gene, lev-11, which has been reported to express four isoforms by using two separate promoters and alternative splicing. Here, we report a fifth tropomyosin isoform, LEV-11O, which is produced by alternative splicing that includes a newly identified seventh exon, exon 7a. By visualizing specific splicing events in vivo, we find that exon 7a is predominantly selected in a subset of the body wall muscles in the head, while exon 7b, which is the alternative to exon 7a, is utilized in the rest of the body. Point mutations in exon 7a and exon 7b cause resistance to levamisole--induced muscle contraction specifically in the head and the main body, respectively. Overexpression of LEV-11O, but not LEV-11A, in the main body results in weak levamisole resistance. These results demonstrate that specific tropomyosin isoforms are expressed in the head and body regions of the muscles and contribute differentially to the regulation of muscle contractility.
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Affiliation(s)
- Dawn E. Barnes
- Department of Pathology, Department of Cell Biology, and Winship Cancer Institute, Emory University, Atlanta, GA 30322
| | - Eichi Watabe
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Kanako Ono
- Department of Pathology, Department of Cell Biology, and Winship Cancer Institute, Emory University, Atlanta, GA 30322
| | - Euiyoung Kwak
- Department of Pathology, Department of Cell Biology, and Winship Cancer Institute, Emory University, Atlanta, GA 30322
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Shoichiro Ono
- Department of Pathology, Department of Cell Biology, and Winship Cancer Institute, Emory University, Atlanta, GA 30322
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Rajabi H, Hiraki M, Kufe D. MUC1-C activates polycomb repressive complexes and downregulates tumor suppressor genes in human cancer cells. Oncogene 2018; 37:2079-2088. [PMID: 29379165 PMCID: PMC5908737 DOI: 10.1038/s41388-017-0096-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/19/2017] [Accepted: 09/29/2017] [Indexed: 12/11/2022]
Abstract
The PRC2 and PRC1 complexes are aberrantly expressed in human cancers and have been linked to decreases in patient survival. MUC1-C is an oncoprotein that is also overexpressed in diverse human cancers and is associated with a poor prognosis. Recent studies have supported a previously unreported function for MUC1-C in activating PRC2 and PRC1 in cancer cells. In the regulation of PRC2, MUC1-C (i) drives transcription of the EZH2 gene, (ii) binds directly to EZH2, and (iii) enhances occupancy of EZH2 on target gene promoters with an increase in H3K27 trimethylation. Regarding PRC1, which is recruited to PRC2 sites in the hierarchical model, MUC1-C induces BMI1 transcription, forms a complex with BMI1, and promotes H2A ubiquitylation. MUC1-C thereby contributes to the integration of PRC2 and PRC1-mediated repression of tumor suppressor genes, such as CDH1, CDKN2A, PTEN and BRCA1. Like PRC2 and PRC1, MUC1-C is associated with the epithelial-mesenchymal transition (EMT) program, cancer stem cell (CSC) state, and acquisition of anticancer drug resistance. In concert with these observations, targeting MUC1-C downregulates EZH2 and BMI1, inhibits EMT and the CSC state, and reverses drug resistance. These findings emphasize the significance of MUC1-C as a therapeutic target for inhibiting aberrant PRC function and reprogramming the epigenome in human cancers.
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Affiliation(s)
- Hasan Rajabi
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Masayuki Hiraki
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
- Department of Gastrointestinal Surgery, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Donald Kufe
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.
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Chang JS, Ha K. A truncated PPAR gamma 2 localizes to mitochondria and regulates mitochondrial respiration in brown adipocytes. PLoS One 2018; 13:e0195007. [PMID: 29566074 PMCID: PMC5864067 DOI: 10.1371/journal.pone.0195007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 03/14/2018] [Indexed: 12/11/2022] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPARγ) is a key regulator of brown adipocyte differentiation and thermogenesis. The PPARγ gene produces two isoforms, PPARγ1 and PPARγ2. PPARγ2 is identical to PPARγ1 except for additional 30 amino acids present in the N-terminus of PPARγ2. Here we report that the C-terminally truncated form of PPARγ2 is predominantly present in the mitochondrial matrix of brown adipocytes and that it binds to the D-loop region of mitochondrial DNA (mtDNA), which contains the promoter for mitochondrial electron transport chain (ETC) genes. Expression of mitochondrially targeted MLS-PPARγ2 in brown adipocytes increases mtDNA-encoded ETC gene expression concomitant with enhanced mitochondrial respiration. These results suggest that direct regulation of mitochondrially encoded ETC gene expression by mitochondrial PPARγ2, in part, underlies the isoform-specific role for PPARγ2 in brown adipocytes.
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Affiliation(s)
- Ji Suk Chang
- Laboratory of Gene Regulation and Metabolism, Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
- * E-mail:
| | - Kyoungsoo Ha
- Laboratory of Gene Regulation and Metabolism, Pennington Biomedical Research Center, Baton Rouge, Louisiana, United States of America
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Thapliyal S, Vasudevan A, Dong Y, Bai J, Koushika SP, Babu K. The C-terminal of CASY-1/Calsyntenin regulates GABAergic synaptic transmission at the Caenorhabditis elegans neuromuscular junction. PLoS Genet 2018. [PMID: 29529030 PMCID: PMC5864096 DOI: 10.1371/journal.pgen.1007263] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The C. elegans ortholog of mammalian calsyntenins, CASY-1, is an evolutionarily conserved type-I transmembrane protein that is highly enriched in the nervous system. Mammalian calsyntenins are strongly expressed at inhibitory synapses, but their role in synapse development and function is still elusive. Here, we report a crucial role for CASY-1 in regulating GABAergic synaptic transmission at the C. elegans neuromuscular junction (NMJ). The shorter isoforms of CASY-1; CASY-1B and CASY-1C, express and function in GABA motor neurons where they regulate GABA neurotransmission. Using pharmacological, behavioral, electrophysiological, optogenetic and imaging approaches we establish that GABA release is compromised at the NMJ in casy-1 mutants. Further, we demonstrate that CASY-1 is required to modulate the transport of GABAergic synaptic vesicle (SV) precursors through a possible interaction with the SV motor protein, UNC-104/KIF1A. This study proposes a possible evolutionarily conserved model for the regulation of GABA synaptic functioning by calsyntenins. GABA acts as a major inhibitory neurotransmitter in both vertebrate and invertebrate nervous systems. Despite the potential deregulation of GABA signaling in several neurological disorders, our understanding of the genetic factors that regulate GABAergic synaptic transmission has just started to evolve. Here, we identify a role for a cell adhesion molecule, CASY-1, in regulating GABA signaling at the C. elegans NMJ. We show that the mutants in casy-1 have reduced number of GABA vesicles at the synapse resulting in less GABA release from the presynaptic GABAergic motor neurons. Further, we show that the shorter isoforms of the casy-1 gene; casy-1b and casy-1c that carry a potential kinesin-motor binding domain are responsible for maintaining GABAergic signaling at the synapse. We show a novel interaction of the CASY-1 isoforms with the C- terminal of the UNC-104/KIF1A motor protein that mediates the trafficking of GABAergic synaptic vesicle precursors to the synapse, thus maintaining normal inhibitory signaling at the NMJ.
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Affiliation(s)
- Shruti Thapliyal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli, Punjab, India
| | - Amruta Vasudevan
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India
| | - Yongming Dong
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 and Department of Biochemistry, University of Washington, Seattle, WA, United Sttaes of America
| | - Jihong Bai
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109 and Department of Biochemistry, University of Washington, Seattle, WA, United Sttaes of America
| | - Sandhya P. Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research, Colaba, Mumbai, India
| | - Kavita Babu
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, SAS Nagar, Manauli, Punjab, India
- * E-mail: ,
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Ghosh M, Thangada S, Dasgupta O, Khanna KM, Yamase HT, Kashgarian M, Hla T, Shapiro LH, Ferrer FA. Cell-intrinsic sphingosine kinase 2 promotes macrophage polarization and renal inflammation in response to unilateral ureteral obstruction. PLoS One 2018. [PMID: 29518138 PMCID: PMC5843290 DOI: 10.1371/journal.pone.0194053] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Sphingosine Kinase-2 (Sphk2) is responsible for the production of the bioactive lipid Sphingosine-1 Phosphate, a key regulator of tissue repair. Here we address the in vivo significance of Sphingosine Kinase -2 in renal inflammation/fibrosis in response to unilateral ureteral obstruction using both genetic and pharmacological strategies. Obstructed kidneys of Sphk2-/- mice showed reduced renal damage and diminished levels of the renal injury markers TGFβ1 and αSMA when compared to wild type controls. We found a consistently significant increase in anti-inflammatory (M2) macrophages in obstructed Sphk2-/- kidneys by flow cytometry and a decrease in mRNA levels of the inflammatory cytokines, MCP1, TNFα, CXCL1 and ILβ1, suggesting an anti-inflammatory bias in the absence of Sphk2. Indeed, metabolic profiling showed that the pro-inflammatory glycolytic pathway is largely inactive in Sphk2-/- bone marrow-derived macrophages. Furthermore, treatment with the M2-promoting cytokines IL-4 or IL-13 demonstrated that macrophages lacking Sphk2 polarized more efficiently to the M2 phenotype than wild type cells. Bone marrow transplant studies indicated that expression of Sphk2-/- on either the hematopoietic or parenchymal cells did not fully rescue the pro-healing phenotype, confirming that both infiltrating M2-macrophages and the kidney microenvironment contribute to the damaging Sphk2 effects. Importantly, obstructed kidneys from mice treated with an Sphk2 inhibitor recapitulated findings in the genetic model. These results demonstrate that reducing Sphk2 activity by genetic or pharmacological manipulation markedly decreases inflammatory and fibrotic responses to obstruction, resulting in diminished renal injury and supporting Sphk2 as a novel driver of the pro-inflammatory macrophage phenotype.
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Affiliation(s)
- Mallika Ghosh
- Center for Vascular Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
- Department of Cell Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
| | - Shobha Thangada
- Center for Vascular Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
- Department of Cell Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
| | - Oisharya Dasgupta
- Center for Vascular Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
- Department of Cell Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
| | - Kamal M. Khanna
- Department of Immunology, University of Connecticut School of Medicine, Farmington, CT, United States of America
| | - Harold T. Yamase
- Department of Pathology, University of Connecticut School of Medicine, Farmington, CT, United States of America
| | - Michael Kashgarian
- Department of Pathology, Yale University Cancer Research Center, New Haven, CT, United States of America
| | - Timothy Hla
- Vascular Biology Program, Boston Children's Hospital, Boston, MA, United States of America
| | - Linda H. Shapiro
- Center for Vascular Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
- Department of Cell Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
- * E-mail: (FAF); (LHS)
| | - Fernando A. Ferrer
- Center for Vascular Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
- Department of Cell Biology, University of Connecticut School of Medicine, Farmington, CT, United States of America
- Section of Pediatric Urology, Children's Hospital of Omaha, Department of Surgery, University of Nebraska School of Medicine, Omaha, NE, United States of America
- * E-mail: (FAF); (LHS)
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Lin BL, Li A, Mun JY, Previs MJ, Previs SB, Campbell SG, Dos Remedios CG, Tombe PDP, Craig R, Warshaw DM, Sadayappan S. Skeletal myosin binding protein-C isoforms regulate thin filament activity in a Ca 2+-dependent manner. Sci Rep 2018; 8:2604. [PMID: 29422607 PMCID: PMC5805719 DOI: 10.1038/s41598-018-21053-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/29/2018] [Indexed: 01/17/2023] Open
Abstract
Muscle contraction, which is initiated by Ca2+, results in precise sliding of myosin-based thick and actin-based thin filament contractile proteins. The interactions between myosin and actin are finely tuned by three isoforms of myosin binding protein-C (MyBP-C): slow-skeletal, fast-skeletal, and cardiac (ssMyBP-C, fsMyBP-C and cMyBP-C, respectively), each with distinct N-terminal regulatory regions. The skeletal MyBP-C isoforms are conditionally coexpressed in cardiac muscle, but little is known about their function. Therefore, to characterize the functional differences and regulatory mechanisms among these three isoforms, we expressed recombinant N-terminal fragments and examined their effect on contractile properties in biophysical assays. Addition of the fragments to in vitro motility assays demonstrated that ssMyBP-C and cMyBP-C activate thin filament sliding at low Ca2+. Corresponding 3D electron microscopy reconstructions of native thin filaments suggest that graded shifts of tropomyosin on actin are responsible for this activation (cardiac > slow-skeletal > fast-skeletal). Conversely, at higher Ca2+, addition of fsMyBP-C and cMyBP-C fragments reduced sliding velocities in the in vitro motility assays and increased force production in cardiac muscle fibers. We conclude that due to the high frequency of Ca2+ cycling in cardiac muscle, cardiac MyBP-C may play dual roles at both low and high Ca2+. However, skeletal MyBP-C isoforms may be tuned to meet the needs of specific skeletal muscles.
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Affiliation(s)
- Brian Leei Lin
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Amy Li
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, 05405, USA
- Bosch Institute, Discipline of Anatomy and Histology, University of Sydney, Sydney, 2006, Australia
| | - Ji Young Mun
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
- Department of Structure and Function of Neural Network, Korea Brain Research Institute, Dong-gu, Daegu, Korea
| | - Michael J Previs
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, 05405, USA
| | - Samantha Beck Previs
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, 05405, USA
| | - Stuart G Campbell
- Departments of Biomedical Engineering and Cellular and Molecular Physiology, Yale University, New Haven, CT, 06520, USA
| | - Cristobal G Dos Remedios
- Bosch Institute, Discipline of Anatomy and Histology, University of Sydney, Sydney, 2006, Australia
| | - Pieter de P Tombe
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Roger Craig
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - David M Warshaw
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, VT, 05405, USA
| | - Sakthivel Sadayappan
- Department of Cell and Molecular Physiology, Health Sciences Division, Loyola University Chicago, Maywood, IL, 60153, USA.
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Schey KL, Petrova RS, Gletten RB, Donaldson PJ. The Role of Aquaporins in Ocular Lens Homeostasis. Int J Mol Sci 2017; 18:E2693. [PMID: 29231874 PMCID: PMC5751294 DOI: 10.3390/ijms18122693] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 12/08/2017] [Accepted: 12/08/2017] [Indexed: 12/13/2022] Open
Abstract
Abstract: Aquaporins (AQPs), by playing essential roles in the maintenance of ocular lens homeostasis, contribute to the establishment and maintenance of the overall optical properties of the lens over many decades of life. Three aquaporins, AQP0, AQP1 and AQP5, each with distinctly different functional properties, are abundantly and differentially expressed in the different regions of the ocular lens. Furthermore, the diversity of AQP functionality is increased in the absence of protein turnover by age-related modifications to lens AQPs that are proposed to alter AQP function in the different regions of the lens. These regional differences in AQP functionality are proposed to contribute to the generation and directionality of the lens internal microcirculation; a system of circulating ionic and fluid fluxes that delivers nutrients to and removes wastes from the lens faster than could be achieved by passive diffusion alone. In this review, we present how regional differences in lens AQP isoforms potentially contribute to this microcirculation system by highlighting current areas of investigation and emphasizing areas where future work is required.
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Affiliation(s)
- Kevin L Schey
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA.
| | - Rosica S Petrova
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
| | - Romell B Gletten
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA.
| | - Paul J Donaldson
- Department of Physiology, School of Medical Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
- School of Optometry and Vison Sciences, New Zealand National Eye Centre, University of Auckland, Auckland 1023, New Zealand.
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Markkanen M, Ludwig A, Khirug S, Pryazhnikov E, Soni S, Khiroug L, Delpire E, Rivera C, Airaksinen MS, Uvarov P. Implications of the N-terminal heterogeneity for the neuronal K-Cl cotransporter KCC2 function. Brain Res 2017; 1675:87-101. [PMID: 28888841 DOI: 10.1016/j.brainres.2017.08.034] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 08/25/2017] [Accepted: 08/30/2017] [Indexed: 12/16/2022]
Abstract
The neuron-specific K-Cl cotransporter KCC2 maintains the low intracellular chloride concentration required for the fast hyperpolarizing responses of the inhibitory neurotransmitters γ-aminobutyric acid (GABA) and glycine. The two KCC2 isoforms, KCC2a and KCC2b differ by their N-termini as a result of alternative promoter usage. Whereas the role of KCC2b in mediating the chloride transport is unequivocal, the physiological role of KCC2a in neurons has remained obscure. We show that KCC2a isoform can decrease the intracellular chloride concentration in cultured neurons and attenuate calcium responses evoked by application of the GABAA receptor agonist muscimol. While the biotinylation assay detected both KCC2 isoforms at the cell surface of cultured neurons, KCC2a was not detected at the plasma membrane in immunostainings, suggesting that the N-terminal KCC2a epitope is masked. Confirming this hypothesis, KCC2a surface expression was detected by the C-terminal KCC2 pan antibody but not by the N-terminal KCC2a antibody in KCC2b-deficient neurons. One possible cause for the epitope masking is the binding site of Ste20-related proline-alanine-rich kinase (SPAK) in the KCC2a N-terminus. SPAK, a known regulator of K-Cl cotransporters, was co-immunoprecipitated in a complex with KCC2a but not KCC2b isoform. Moreover, SPAK overexpression decreased the transport activity of KCC2a but not that of KCC2b, as revealed by rubidium flux assay in HEK293 cells. Thus, our data indicate that both KCC2 isoforms perform as chloride cotransporters in neuronal cells, while their N-terminal heterogeneity could play an important role in fine-tuning of the K-Cl transport activity.
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Affiliation(s)
- Marika Markkanen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | | | | | | | - Shetal Soni
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Leonard Khiroug
- Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Claudio Rivera
- Neuroscience Center, University of Helsinki, Helsinki, Finland; INSERM, Institut de Neurobiologie de la Méditerranée (INMED), Marseille, France; Aix-Marseille Université, UMR901 Marseille, France
| | - Matti S Airaksinen
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
| | - Pavel Uvarov
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
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Bagheri-Fam S, Bird AD, Zhao L, Ryan JM, Yong M, Wilhelm D, Koopman P, Eswarakumar VP, Harley VR. Testis Determination Requires a Specific FGFR2 Isoform to Repress FOXL2. Endocrinology 2017; 158:3832-3843. [PMID: 28938467 PMCID: PMC5695826 DOI: 10.1210/en.2017-00674] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 09/05/2017] [Indexed: 02/03/2023]
Abstract
Male sex determination in mammals relies on sex determining region Y-mediated upregulation of sex determining region-box 9 (SOX9) expression in XY gonads, whereas Wnt family member (WNT)/R-spondin 1 signaling and forkhead box L2 (FOXL2) drive female sex determination in XX gonads. Fibroblast growth factor (FGF) 9 signaling ensures sustained SOX9 expression through repression of one of the ovarian pathways (WNT signaling), whereas the significance of FGF-mediated repression of the FOXL2 pathway has not been studied. Previously, we demonstrated that FGFR2 is the receptor for FGF9 in the XY gonad. Whether a specific isoform (FGFR2b or FGFR2c) is required was puzzling. Here, we show that FGFR2c is required for male sex determination. Initially, in developing mouse embryos at 12.5 to 13.5 days postcoitum (dpc), XY Fgfr2c-/- gonads appear as ovotestes, with SOX9 and FOXL2 expression predominantly localized to the posterior and anterior gonadal poles, respectively. However, by 15.5 dpc, XY Fgfr2c-/- gonads show complete male-to-female sex reversal, evident by the lack of SOX9 and ectopic expression of FOXL2 throughout the gonads. Furthermore, ablation of the Foxl2 gene leads to partial or complete rescue of gonadal sex reversal in XY Fgfr2c-/- mice. Together with previous findings, our data suggest that testis determination involves FGFR2c-mediated repression of both the WNT4- and FOXL2-driven ovarian-determining pathways.
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Affiliation(s)
- Stefan Bagheri-Fam
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Monash Medical Centre, Melbourne, Victoria 3168, Australia
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Anthony D. Bird
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Monash Medical Centre, Melbourne, Victoria 3168, Australia
| | - Liang Zhao
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Janelle M. Ryan
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Monash Medical Centre, Melbourne, Victoria 3168, Australia
| | - Meiyun Yong
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Monash Medical Centre, Melbourne, Victoria 3168, Australia
- Department of Anatomy and Developmental Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Dagmar Wilhelm
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Peter Koopman
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Veraragavan P. Eswarakumar
- Department of Orthopaedics and Rehabilitation, Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Vincent R. Harley
- Centre for Endocrinology and Metabolism, Hudson Institute of Medical Research, Monash Medical Centre, Melbourne, Victoria 3168, Australia
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Kim M, Gwak Y, Jung W, Jin E. Identification and Characterization of an Isoform Antifreeze Protein from the Antarctic Marine Diatom, Chaetoceros neogracile and Suggestion of the Core Region. Mar Drugs 2017; 15:md15100318. [PMID: 29057803 PMCID: PMC5666426 DOI: 10.3390/md15100318] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 10/13/2017] [Accepted: 10/16/2017] [Indexed: 11/16/2022] Open
Abstract
Antifreeze proteins (AFPs) protecting the cells against freezing are produced in response to extremely low temperatures in diverse psychrophilic organisms, and they are encoded by multiple gene families. The AFP of Antarctic marine diatom Chaetoceros neogracile is reported in our previous research, but like other microalgae, was considered to probably have additional genes coding AFPs. In this paper, we reported the cloning and characterization of additional AFP gene from C. neogracile (Cn-isoAFP). Cn-isoAFP protein is 74.6% identical to the previously reported Cn-AFP. The promoter sequence of Cn-isoAFP contains environmental stress responsive elements for cold, thermal, and high light conditions. Cn-isoAFP transcription levels increased dramatically when cells were exposed to freezing (−20 °C), thermal (10 °C), or high light (600 μmol photon m−2 s−1) stresses. The thermal hysteresis (TH) activity of recombinant Cn-isoAFP was 0.8 °C at a protein concentration of 5 mg/mL. Results from homology modeling and TH activity analysis of site-directed mutant proteins elucidated AFP mechanism to be a result of flatness of B-face maintained via hydrophobic interactions.
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Affiliation(s)
- Minjae Kim
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 133-791, Korea.
| | - Yunho Gwak
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 133-791, Korea.
| | - Woongsic Jung
- Division of Polar Life Science, Korea Polar Research Institute, KIOST, Incheon 406-840, Korea.
| | - EonSeon Jin
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 133-791, Korea.
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Belfiore A, Malaguarnera R, Vella V, Lawrence MC, Sciacca L, Frasca F, Morrione A, Vigneri R. Insulin Receptor Isoforms in Physiology and Disease: An Updated View. Endocr Rev 2017; 38:379-431. [PMID: 28973479 PMCID: PMC5629070 DOI: 10.1210/er.2017-00073] [Citation(s) in RCA: 234] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/13/2017] [Indexed: 02/08/2023]
Abstract
The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.
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Affiliation(s)
- Antonino Belfiore
- Endocrinology, Department of Health Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Roberta Malaguarnera
- Endocrinology, Department of Health Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Veronica Vella
- School of Human and Social Sciences, University Kore of Enna, via della Cooperazione, 94100 Enna, Italy
| | - Michael C. Lawrence
- Structural Biology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Laura Sciacca
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
| | - Francesco Frasca
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
| | - Andrea Morrione
- Department of Urology and Biology of Prostate Cancer Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Riccardo Vigneri
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
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Balbi P, Massobrio P, Hellgren Kotaleski J. A single Markov-type kinetic model accounting for the macroscopic currents of all human voltage-gated sodium channel isoforms. PLoS Comput Biol 2017; 13:e1005737. [PMID: 28863150 PMCID: PMC5599066 DOI: 10.1371/journal.pcbi.1005737] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 09/14/2017] [Accepted: 08/23/2017] [Indexed: 11/19/2022] Open
Abstract
Modelling ionic channels represents a fundamental step towards developing biologically detailed neuron models. Until recently, the voltage-gated ion channels have been mainly modelled according to the formalism introduced by the seminal works of Hodgkin and Huxley (HH). However, following the continuing achievements in the biophysical and molecular comprehension of these pore-forming transmembrane proteins, the HH formalism turned out to carry limitations and inconsistencies in reproducing the ion-channels electrophysiological behaviour. At the same time, Markov-type kinetic models have been increasingly proven to successfully replicate both the electrophysiological and biophysical features of different ion channels. However, in order to model even the finest non-conducting molecular conformational change, they are often equipped with a considerable number of states and related transitions, which make them computationally heavy and less suitable for implementation in conductance-based neurons and large networks of those. In this purely modelling study we develop a Markov-type kinetic model for all human voltage-gated sodium channels (VGSCs). The model framework is detailed, unifying (i.e., it accounts for all ion-channel isoforms) and computationally efficient (i.e. with a minimal set of states and transitions). The electrophysiological data to be modelled are gathered from previously published studies on whole-cell patch-clamp experiments in mammalian cell lines heterologously expressing the human VGSC subtypes (from NaV1.1 to NaV1.9). By adopting a minimum sequence of states, and using the same state diagram for all the distinct isoforms, the model ensures the lightest computational load when used in neuron models and neural networks of increasing complexity. The transitions between the states are described by original ordinary differential equations, which represent the rate of the state transitions as a function of voltage (i.e., membrane potential). The kinetic model, developed in the NEURON simulation environment, appears to be the simplest and most parsimonious way for a detailed phenomenological description of the human VGSCs electrophysiological behaviour.
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Affiliation(s)
- Pietro Balbi
- Department of Neurorehabilitation, Scientific Institute of Pavia via Boezio IRCCS, Istituti Clinici Scientifici Maugeri SpA, Pavia, Italy
| | - Paolo Massobrio
- Department of Informatics, Bioengineering, Robotics and System Engineering (DIBRIS), University of Genova, Genova, Italy
| | - Jeanette Hellgren Kotaleski
- Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
- Department of Computational Science and Technology, School of Computer Science and Communication, KTH The Royal Institute of Technology, Stockholm, Sweden
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Ghadie MA, Lambourne L, Vidal M, Xia Y. Domain-based prediction of the human isoform interactome provides insights into the functional impact of alternative splicing. PLoS Comput Biol 2017; 13:e1005717. [PMID: 28846689 PMCID: PMC5591010 DOI: 10.1371/journal.pcbi.1005717] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 09/08/2017] [Accepted: 08/03/2017] [Indexed: 11/19/2022] Open
Abstract
Alternative splicing is known to remodel protein-protein interaction networks (“interactomes”), yet large-scale determination of isoform-specific interactions remains challenging. We present a domain-based method to predict the isoform interactome from the reference interactome. First, we construct the domain-resolved reference interactome by mapping known domain-domain interactions onto experimentally-determined interactions between reference proteins. Then, we construct the isoform interactome by predicting that an isoform loses an interaction if it loses the domain mediating the interaction. Our prediction framework is of high-quality when assessed by experimental data. The predicted human isoform interactome reveals extensive network remodeling by alternative splicing. Protein pairs interacting with different isoforms of the same gene tend to be more divergent in biological function, tissue expression, and disease phenotype than protein pairs interacting with the same isoforms. Our prediction method complements experimental efforts, and demonstrates that integrating structural domain information with interactomes provides insights into the functional impact of alternative splicing. Protein-protein interaction networks have been extensively used in systems biology to study the role of proteins in cell function and disease. However, current network biology studies typically assume that one gene encodes one protein isoform, ignoring the effect of alternative splicing. Alternative splicing allows a gene to produce multiple protein isoforms, by alternatively selecting distinct regions in the gene to be translated to protein products. Here, we present a computational method to predict and analyze the large-scale effect of alternative splicing on protein-protein interaction networks. Starting with a reference protein-protein interaction network determined by experiments, our method annotates protein-protein interactions with domain-domain interactions, and predicts that a protein isoform loses an interaction if it loses the domain mediating the interaction as a result of alternative splicing. Our predictions reveal the central role of alternative splicing in extensively remodeling the human protein-protein interaction network, and in increasing the functional complexity of the human cell. Our prediction method complements ongoing experimental efforts by predicting isoform-specific interactions for genes not tested yet by experiments and providing insights into the functional impact of alternative splicing.
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Affiliation(s)
- Mohamed Ali Ghadie
- Department of Bioengineering, McGill University, Montreal, Québec, Canada
| | - Luke Lambourne
- Department of Bioengineering, McGill University, Montreal, Québec, Canada
| | - Marc Vidal
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yu Xia
- Department of Bioengineering, McGill University, Montreal, Québec, Canada
- Center for Cancer Systems Biology (CCSB), Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
- * E-mail:
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Abstract
Since at least the 1920s, it has been reported that common chimpanzees (Pan troglodytes) differ from humans in being capable of exceptional feats of "super strength," both in the wild and in captive environments. A mix of anecdotal and more controlled studies provides some support for this view; however, a critical review of available data suggests that chimpanzee mass-specific muscular performance is a more modest 1.5 times greater than humans on average. Hypotheses for the muscular basis of this performance differential have included greater isometric force-generating capabilities, faster maximum shortening velocities, and/or a difference in myosin heavy chain (MHC) isoform content in chimpanzee relative to human skeletal muscle. Here, we show that chimpanzee muscle is similar to human muscle in its single-fiber contractile properties, but exhibits a much higher fraction of MHC II isoforms. Unlike humans, chimpanzee muscle is composed of ∼67% fast-twitch fibers (MHC IIa+IId). Computer simulations of species-specific whole-muscle models indicate that maximum dynamic force and power output is 1.35 times higher in a chimpanzee muscle than a human muscle of similar size. Thus, the superior mass-specific muscular performance of chimpanzees does not stem from differences in isometric force-generating capabilities or maximum shortening velocities-as has long been suggested-but rather is due in part to differences in MHC isoform content and fiber length. We propose that the hominin lineage experienced a decline in maximum dynamic force and power output during the past 7-8 million years in response to selection for repetitive, low-cost contractile behavior.
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Affiliation(s)
- Matthew C O'Neill
- Department of Basic Medical Sciences, University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004;
| | - Brian R Umberger
- Department of Kinesiology, University of Massachusetts, Amherst, MA 01003
| | - Nicholas B Holowka
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138
| | - Susan G Larson
- Department of Anatomical Sciences, Stony Brook University School of Medicine, Stony Brook, NY 11794
| | - Peter J Reiser
- Division of Biosciences, The Ohio State University College of Dentistry, Columbus, OH 43210
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James TF, Nenov MN, Tapia CM, Lecchi M, Koshy S, Green TA, Laezza F. Consequences of acute Na v1.1 exposure to deltamethrin. Neurotoxicology 2017; 60:150-160. [PMID: 28007400 PMCID: PMC5447465 DOI: 10.1016/j.neuro.2016.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 12/02/2016] [Accepted: 12/14/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND Pyrethroid insecticides are the most popular class of insecticides in the world, despite their near-ubiquity, their effects of delaying the onset of inactivation of voltage-gated sodium (Nav) channels have not been well-evaluated in all the mammalian Nav isoforms. OBJECTIVE Here we compare the well-studied Nav1.6 isoforms to the less-understood Nav1.1 in their responses to acute deltamethrin exposure. METHODS We used patch-clamp electrophysiology to record sodium currents encoded by either Nav1.1 or Nav1.6 channels stably expressed in HEK293 cells. Protocols evaluating both resting and use-dependent modification were employed. RESULTS We found that exposure of both isoforms to 10μM deltamethrin significantly potentiated persistent and tail current densities without affecting peak transient current densities, and only Nav1.1 maintained these significant effects at 1μM deltamethrin. Window currents increased for both as well, and while only Nav1.6 displayed changes in activation slope and V1/2 of steady-state inactivation for peak currents, V1/2 of persistent current activation was hyperpolarized of ∼10mV by deltamethrin in Nav1.1 cells. Evaluating use-dependence, we found that deltamethrin again potentiated persistent and tail current densities in both isoforms, but only Nav1.6 demonstrated use-dependent enhancement, indicating the primary deltamethrin-induced effects on Nav1.1 channels are not use-dependent. CONCLUSION Collectively, these data provide evidence that Nav1.1 is indeed vulnerable to deltamethrin modification at lower concentrations than Nav1.6, and this effect is primarily mediated during the resting state. GENERAL SIGNIFICANCE These findings identify Nav1.1 as a novel target of pyrethroid exposure, which has major implications for the etiology of neuropsychiatric disorders associated with loss of Nav1.1-expressing inhibitory neurons.
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Affiliation(s)
- T F James
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, USA; Neuroscience Graduate Program, University of Texas Medical Branch, USA
| | - Miroslav N Nenov
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, USA
| | - Cynthia M Tapia
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, USA
| | - Marzia Lecchi
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Italy
| | - Shyny Koshy
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, USA; Center for Addiction Research, University of Texas Medical Branch, USA
| | - Thomas A Green
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, USA; Center for Addiction Research, University of Texas Medical Branch, USA
| | - Fernanda Laezza
- Department of Pharmacology & Toxicology, University of Texas Medical Branch, USA; Mitchell Center for Neurodegenerative Diseases, USA; Center for Environmental Toxicology, University of Texas Medical Branch, USA; Center for Addiction Research, University of Texas Medical Branch, USA.
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43
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Simiczyjew A, Mazur AJ, Dratkiewicz E, Nowak D. Involvement of β- and γ-actin isoforms in actin cytoskeleton organization and migration abilities of bleb-forming human colon cancer cells. PLoS One 2017; 12:e0173709. [PMID: 28333953 PMCID: PMC5363831 DOI: 10.1371/journal.pone.0173709] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 02/15/2017] [Indexed: 12/13/2022] Open
Abstract
Amoeboid movement is characteristic for rounded cells, which do not form strong adhesion contacts with the ECM and use blebs as migratory protrusions. It is well known that actin is the main component of mature forms of these structures, but the exact role fulfilled by non-muscle actin isoforms β- and γ- in bleb formation and migration of these cells is still not fully understood. The aim of this study was to establish the role of β- and γ-actin in migration of bleb-forming cancer cells using isoform-specific antibodies and expression of fluorescently tagged actin isoforms. We observed, after staining with monoclonal antibodies, that both actins are present in these cells in the form of a cortical ring as well as in the area of blebs. Additionally, using simultaneous expression of differentially tagged β- and γ-actin in cells, we observed that the actin isoforms are present together in a single bleb. They were involved during bleb expansion as well as retraction. Also present in the area of these protrusions formed by both isoforms were the bleb markers–ezrin and myosin II. The overexpression of β- or γ-actin led to actin cytoskeletal rearrangement followed by the growth of migration and invasion abilities of examined human colon cancer cells, LS174T line. In summary these data prove that both actin isoforms have an impact on motility of bleb-forming cancer cells. Moreover, we conclude that monoclonal antibodies directed against actin isoforms in combination with the tagged actins are good tools to study their role in important biological processes.
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Affiliation(s)
- Aleksandra Simiczyjew
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, Poland
- * E-mail:
| | - Antonina Joanna Mazur
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, Poland
| | - Ewelina Dratkiewicz
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, Poland
| | - Dorota Nowak
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Joliot-Curie 14a, Wroclaw, Poland
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44
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Egunsola AT, Bae Y, Jiang MM, Liu DS, Chen-Evenson Y, Bertin T, Chen S, Lu JT, Nevarez L, Magal N, Raas-Rothschild A, Swindell EC, Cohn DH, Gibbs RA, Campeau PM, Shohat M, Lee BH. Loss of DDRGK1 modulates SOX9 ubiquitination in spondyloepimetaphyseal dysplasia. J Clin Invest 2017; 127:1475-1484. [PMID: 28263186 DOI: 10.1172/jci90193] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 01/12/2017] [Indexed: 01/08/2023] Open
Abstract
Shohat-type spondyloepimetaphyseal dysplasia (SEMD) is a skeletal dysplasia that affects cartilage development. Similar skeletal disorders, such as spondyloepiphyseal dysplasias, are linked to mutations in type II collagen (COL2A1), but the causative gene in SEMD is not known. Here, we have performed whole-exome sequencing to identify a recurrent homozygous c.408+1G>A donor splice site loss-of-function mutation in DDRGK domain containing 1 (DDRGK1) in 4 families affected by SEMD. In zebrafish, ddrgk1 deficiency disrupted craniofacial cartilage development and led to decreased levels of the chondrogenic master transcription factor sox9 and its downstream target, col2a1. Overexpression of sox9 rescued the zebrafish chondrogenic and craniofacial phenotype generated by ddrgk1 knockdown, thus identifying DDRGK1 as a regulator of SOX9. Consistent with these results, Ddrgk1-/- mice displayed delayed limb bud chondrogenic condensation, decreased SOX9 protein expression and Col2a1 transcript levels, and increased apoptosis. Furthermore, we determined that DDRGK1 can directly bind to SOX9 to inhibit its ubiquitination and proteasomal degradation. Taken together, these data indicate that loss of DDRGK1 decreases SOX9 expression and causes a human skeletal dysplasia, identifying a mechanism that regulates chondrogenesis via modulation of SOX9 ubiquitination.
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45
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Abstract
The clustering of signaling molecules at specialized cellular sites allows cells to effectively convert extracellular signals into intracellular signals and to produce a concerted functional output with specific temporal and spatial patterns. A prime example for these molecules and their effects on cellular signaling are the postsynaptic density proteins of the central nervous system. Recently, one group of these proteins, the Vesl/Homer protein family has received increased attention because of its unique molecular properties that allow both the clustering end functional modulation of a plethora of different binding Proteins. Within multlprotein signaling complexes, Vesl/Homer Proteins influence proteins as diverse as metabotropic glutamate receptors; transient receptor potential channels; intracellular calcium channels; the scaffolding protein, Shank; small GTPases; transcription factors; and cytoskeletal proteins. Furthermore, interaction with such functionally relevant proteins also links Vesl/Homer proteins indirectly to an even larger group of cellular effector proteins, putting the Vesl/Homer Proteins at the crossroads of several critical intracellular signaling processes. In addition to the initial reports of Vesl/Homer protein expression in the central nervous system, members of this protein family have now been identified in other excitable cells in various muscle types and in a large number of nonexcitable cells. The widespread expression of Vesl/Homer proteins in different organs and their functional importance in cellular protein signaling complexes is further evidenced by their conservation in organisms from Drosoohila to humans.
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Affiliation(s)
- R Scott Duncan
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, 3500 Camp Bowie Boulevard, Fort Worth, Texas 76107-2699, USA
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46
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Abstract
Previous experiments have shown that dietary n-6 and n-3 polyenoic fatty acids (PFA) have different effects on collagen production, a process that may be related to the formation of prostaglandins (PG). This study tested the hypothesis that fibroblast collagen production could be regulated by different n-6:n-3 PFA ratios and that the effects were mediated by PGE2 and altered signaling via the different PGE receptor subtypes. Compared to a bovine serum albumin control, eicosapentaenoic acid (EPA; 20:5 n-3) treated cells significantly (P < 0.05) increased both collagen production and collagen as a percentage of total cellular protein (C-PTP), but arachidonic acid (AA; 20:4 n-6) reduced collagen production and C-PTP. As the amount of AA decreased and that of EPA increased, collagen production and C-PTP increased, especially when ratio of n-6:n-3 PFA was less than 1:1. C-PTP was significantly correlated with the amount of PGE2 in the medium. AA- or EPA-treated cells produced similar C-PTP when incubated with 10−6 M indomethacin, a cyclooxygenase inhibitor. Addition of exogenous PGE2 to cell cultures treated with 10−6 M indomethacin for 48 hrs decreased C-PTP in both AA and EPA groups. Decreased C-PTP was observed in AA-treated cells exposed to EP1, EP2, and EP4 PGE receptor agonists and in EPA-treated cells exposed to EP2 and EP4 agonists. AA-treated cell responded to activators of cyclic adenosine monophosphate and protein kinase C by decreasing C-PTP, but EPA-treated cells were unresponsive. In conclusion, collagen production in 3T3-Swiss fibroblasts induced by different n-6:n-3 PFA ratios was correlated with PGE2 production and altered responsiveness and signaling via the different PGE receptor subtypes.
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Affiliation(s)
- Yi Jia
- Purdue University, Department of Basic Medical Sciences, 625 Harrison Street, West Lafayette, IN 47907-2026, USA
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47
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Campbell RF, Walthall WW. Meis/UNC-62 isoform dependent regulation of CoupTF-II/UNC-55 and GABAergic motor neuron subtype differentiation. Dev Biol 2016; 419:250-261. [PMID: 27634571 DOI: 10.1016/j.ydbio.2016.09.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/24/2016] [Accepted: 09/09/2016] [Indexed: 11/28/2022]
Abstract
Gene regulatory networks orchestrate the assembly of functionally related cells within a cellular network. Subtle differences often exist among functionally related cells within such networks. How differences are created among cells with similar functions has been difficult to determine due to the complexity of both the gene and the cellular networks. In Caenorhabditis elegans, the DD and VD motor neurons compose a cross-inhibitory, GABAergic network that coordinates dorsal and ventral muscle contractions during locomotion. The Pitx2 homologue, UNC-30, acts as a terminal selector gene to create similarities and the Coup-TFII homologue, UNC-55, is necessary for creating differences between the two motor neuron classes. What is the organizing gene regulatory network responsible for initiating the expression of UNC-55 and thus creating differences between the DD and VD motor neurons? We show that the unc-55 promoter has modules that contain Meis/UNC-62 binding sites. These sites can be subdivided into regions that are capable of activating or repressing UNC-55 expression in different motor neurons. Interestingly, different isoforms of UNC-62 are responsible for the activation and the stabilization of unc-55 transcription. Furthermore, specific isoforms of UNC-62 are required for proper synaptic patterning of the VD motor neurons. Isoform specific regulation of differentiating neurons is a relatively unexplored area of research and presents a mechanism for creating differences among functionally related cells within a network.
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MESH Headings
- Animals
- Animals, Genetically Modified
- CRISPR-Cas Systems
- Caenorhabditis elegans/genetics
- Caenorhabditis elegans/physiology
- Caenorhabditis elegans Proteins/biosynthesis
- Caenorhabditis elegans Proteins/physiology
- GABAergic Neurons/cytology
- Gene Expression Regulation, Developmental
- Gene Regulatory Networks/genetics
- Genes, Reporter
- Homeodomain Proteins/physiology
- Motor Neurons/classification
- Motor Neurons/cytology
- Neurogenesis/genetics
- Promoter Regions, Genetic/genetics
- Protein Isoforms/physiology
- RNA, Helminth/biosynthesis
- RNA, Helminth/genetics
- RNA, Messenger/biosynthesis
- RNA, Messenger/genetics
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/physiology
- Receptors, Cytoplasmic and Nuclear/biosynthesis
- Receptors, Cytoplasmic and Nuclear/physiology
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Transcription Factors
- Transcription, Genetic/genetics
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Richard F Campbell
- Department of Biology, Georgia State University, Atlanta, GA 30303, United States
| | - Walter W Walthall
- Department of Biology, Georgia State University, Atlanta, GA 30303, United States.
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48
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Röhrle O, Neumann V, Heidlauf T. The Role of Parvalbumin, Sarcoplasmatic Reticulum Calcium Pump Rate, Rates of Cross-Bridge Dynamics, and Ryanodine Receptor Calcium Current on Peripheral Muscle Fatigue: A Simulation Study. Comput Math Methods Med 2016; 2016:3180205. [PMID: 27980606 PMCID: PMC5131563 DOI: 10.1155/2016/3180205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/18/2016] [Accepted: 08/21/2016] [Indexed: 11/23/2022]
Abstract
A biophysical model of the excitation-contraction pathway, which has previously been validated for slow-twitch and fast-twitch skeletal muscles, is employed to investigate key biophysical processes leading to peripheral muscle fatigue. Special emphasis hereby is on investigating how the model's original parameter sets can be interpolated such that realistic behaviour with respect to contraction time and fatigue progression can be obtained for a continuous distribution of the model's parameters across the muscle units, as found for the functional properties of muscles. The parameters are divided into 5 groups describing (i) the sarcoplasmatic reticulum calcium pump rate, (ii) the cross-bridge dynamics rates, (iii) the ryanodine receptor calcium current, (iv) the rates of binding of magnesium and calcium ions to parvalbumin and corresponding dissociations, and (v) the remaining processes. The simulations reveal that the first two parameter groups are sensitive to contraction time but not fatigue, the third parameter group affects both considered properties, and the fourth parameter group is only sensitive to fatigue progression. Hence, within the scope of the underlying model, further experimental studies should investigate parvalbumin dynamics and the ryanodine receptor calcium current to enhance the understanding of peripheral muscle fatigue.
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Affiliation(s)
- Oliver Röhrle
- Institute of Applied Mechanics (CE), University of Stuttgart, Stuttgart, Germany
- Stuttgart Research Centre for Simulation Technology (SimTech), University of Stuttgart, Stuttgart, Germany
| | - Verena Neumann
- Institute of Applied Mechanics (CE), University of Stuttgart, Stuttgart, Germany
| | - Thomas Heidlauf
- Institute of Applied Mechanics (CE), University of Stuttgart, Stuttgart, Germany
- Stuttgart Research Centre for Simulation Technology (SimTech), University of Stuttgart, Stuttgart, Germany
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49
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Brahimi F, Maira M, Barcelona PF, Galan A, Aboulkassim T, Teske K, Rogers ML, Bertram L, Wang J, Yousefi M, Rush R, Fabian M, Cashman N, Saragovi HU. The Paradoxical Signals of Two TrkC Receptor Isoforms Supports a Rationale for Novel Therapeutic Strategies in ALS. PLoS One 2016; 11:e0162307. [PMID: 27695040 PMCID: PMC5047590 DOI: 10.1371/journal.pone.0162307] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 08/19/2016] [Indexed: 12/14/2022] Open
Abstract
Full length TrkC (TrkC-FL) is a receptor tyrosine kinase whose mRNA can be spliced to a truncated TrkC.T1 isoform lacking the kinase domain. Neurotrophin-3 (NT-3) activates TrkC-FL to maintain motor neuron health and function and TrkC.T1 to produce neurotoxic TNF-α; hence resulting in opposing pathways. In mouse and human ALS spinal cord, the reduction of miR-128 that destabilizes TrkC.T1 mRNA results in up-regulated TrkC.T1 and TNF-α in astrocytes. We exploited conformational differences to develop an agonistic mAb 2B7 that selectively activates TrkC-FL, to circumvent TrkC.T1 activation. In mouse ALS, 2B7 activates spinal cord TrkC-FL signals, improves spinal cord motor neuron phenotype and function, and significantly prolongs life-span. Our results elucidate biological paradoxes of receptor isoforms and their role in disease progression, validate the concept of selectively targeting conformational epitopes in naturally occurring isoforms, and may guide the development of pro-neuroprotective (TrkC-FL) and anti-neurotoxic (TrkC.T1) therapeutic strategies.
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Affiliation(s)
- Fouad Brahimi
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
| | - Mario Maira
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
| | - Pablo F. Barcelona
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
| | - Alba Galan
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
| | - Tahar Aboulkassim
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
| | - Katrina Teske
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
| | - Mary-Louise Rogers
- Flinders University, Department of Human Physiology, Centre for Neuroscience, Adelaide, Australia
| | - Lisa Bertram
- University of British Columbia. Brain Research Centre, Vancouver, Canada
| | - Jing Wang
- University of British Columbia. Brain Research Centre, Vancouver, Canada
| | - Masoud Yousefi
- University of British Columbia. Brain Research Centre, Vancouver, Canada
| | - Robert Rush
- Flinders University, Department of Human Physiology, Centre for Neuroscience, Adelaide, Australia
| | - Marc Fabian
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
- Department of Biochemistry. McGill University, Montréal, QC, Canada
| | - Neil Cashman
- University of British Columbia. Brain Research Centre, Vancouver, Canada
| | - H. Uri Saragovi
- Lady Davis Institute-Jewish General Hospital, Translational Center, McGill University, Montréal, QC, Canada
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada
- * E-mail:
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Abstract
The objective of this study is to confirm the precise glucose transporter (GLUT) 8 localization and determine the expression of GLUT9a and GLUT9b by Western blot and confocal and immunoelectron microscopy in the mouse testis and sperm. GLUT8, GLUT9a, and GLUT9b proteins are expressed in the most intraseminiferous tubula cells and Leydig cells. GLUT8 localizes in the midpiece and principal piece as well as in the acrosomal region of the sperm. Immunoelectron microscopic analysis shows that GLUT8 is strongly detectable at the acrosome and neck region of the sperm. In the midpiece, GLUT8 localizes at the outer dense fibers (odf) as well as at the circumference of the spiral mitochondria. In the principal piece, GLUT8 localizes at the odf. GLUT9a strictly localizes in the midpiece, but GLUT9b localizes in the acrosome, midpiece, and principal piece of the sperm. These results suggest that glucose uptake via GLUT8, GLUT9a, and GLUT9b likely affects normal spermatogenesis, steroidogenesis, and sperm function in the mouse.
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Affiliation(s)
- Sung Tae Kim
- Department of Obstetrics and Gynecology,Washington University in St Louis, St Louis, Missouri 63110, USA
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