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Shultz KD, Al Anbari YF, Wright NT. I told you to stop: obscurin's role in epithelial cell migration. Biochem Soc Trans 2024; 52:1947-1956. [PMID: 39051125 DOI: 10.1042/bst20240564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 07/02/2024] [Accepted: 07/11/2024] [Indexed: 07/27/2024]
Abstract
The giant cytoskeletal protein obscurin contains multiple cell signaling domains that influence cell migration. Here, we follow each of these pathways, examine how these pathways modulate epithelial cell migration, and discuss the cross-talk between these pathways. Specifically, obscurin uses its PH domain to inhibit phosphoinositide-3-kinase (PI3K)-dependent migration and its RhoGEF domain to activate RhoA and slow cell migration. While obscurin's effect on the PI3K pathway agrees with the literature, obscurin's effect on the RhoA pathway runs counter to most other RhoA effectors, whose activation tends to lead to enhanced motility. Obscurin also phosphorylates cadherins, and this may also influence cell motility. When taken together, obscurin's ability to modulate three independent cell migration pathways is likely why obscurin knockout cells experience enhanced epithelial to mesenchymal transition, and why obscurin is a frequently mutated gene in several types of cancer.
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Affiliation(s)
- Kamrin D Shultz
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, U.S.A
| | - Yasmin F Al Anbari
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, U.S.A
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, 901 Carrier Dr., Harrisonburg, VA 22807, U.S.A
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2
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Sanfeliu-Cerdán N, Català-Castro F, Mateos B, Garcia-Cabau C, Ribera M, Ruider I, Porta-de-la-Riva M, Canals-Calderón A, Wieser S, Salvatella X, Krieg M. A MEC-2/stomatin condensate liquid-to-solid phase transition controls neuronal mechanotransduction during touch sensing. Nat Cell Biol 2023; 25:1590-1599. [PMID: 37857834 PMCID: PMC10635833 DOI: 10.1038/s41556-023-01247-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 09/01/2023] [Indexed: 10/21/2023]
Abstract
A growing body of work suggests that the material properties of biomolecular condensates ensuing from liquid-liquid phase separation change with time. How this aging process is controlled and whether the condensates with distinct material properties can have different biological functions is currently unknown. Using Caenorhabditis elegans as a model, we show that MEC-2/stomatin undergoes a rigidity phase transition from fluid-like to solid-like condensates that facilitate transport and mechanotransduction, respectively. This switch is triggered by the interaction between the SH3 domain of UNC-89 (titin/obscurin) and MEC-2. We suggest that this rigidity phase transition has a physiological role in frequency-dependent force transmission in mechanosensitive neurons during body wall touch. Our data demonstrate a function for the liquid and solid phases of MEC-2/stomatin condensates in facilitating transport or mechanotransduction, and a previously unidentified role for titin homologues in neurons.
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Affiliation(s)
- Neus Sanfeliu-Cerdán
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Frederic Català-Castro
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Borja Mateos
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Carla Garcia-Cabau
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Maria Ribera
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Iris Ruider
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Montserrat Porta-de-la-Riva
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Adrià Canals-Calderón
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Stefan Wieser
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain
| | - Xavier Salvatella
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Spain.
- ICREA, Barcelona, Spain.
| | - Michael Krieg
- ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona), Spain.
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3
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Mauriello GE, Moncure GE, Nowzari RA, Miller CJ, Wright NT. The N-terminus of obscurin is flexible in solution. Proteins 2023; 91:485-496. [PMID: 36306263 DOI: 10.1002/prot.26442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 10/13/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022]
Abstract
The N-terminal half of the giant cytoskeletal protein obscurin is comprised of more than 50 Ig-like domains, arranged in tandem. Domains 18-51 are connected to each other through short 5-residue linkers, and this arrangement has been previously shown to form a semi-flexible rod in solution. Domains 1-18 generally have slightly longer ~7 residue interdomain linkers, and the multidomain structure and motion conferred by this kind of linker is understudied. Here, we use NMR, SAXS, and MD to show that these longer linkers are associated with significantly more domain/domain flexibility, with the resulting multidomain structure being moderately compact. Further examination of the relationship between interdomain flexibility and linker length shows there is a 5 residue "sweet spot" linker length that results in dual-domain systems being extended, and conversely that both longer or shorter linkers result in a less extended structure. This detailed knowledge of the obscurin N terminus structure and flexibility allowed for mathematical modeling of domains 1-18, which suggests that this region likely forms tangles if left alone in solution. Given how infrequently protein tangles occur in nature, and given the pathological outcomes that occur when tangles do arise, our data suggest that obscurin is likely either significantly scaffolded or else externally extended in the cell.
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Affiliation(s)
- Gianna E Mauriello
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Grace E Moncure
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Roujon A Nowzari
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
| | - Callie J Miller
- Department of Engineering, James Madison University, Harrisonburg, Virginia, USA
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, USA
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4
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Guardia T, Zhang Y, Thompson KN, Lee SJ, Martin SS, Konstantopoulos K, Kontrogianni-Konstantopoulos A. OBSCN restoration via OBSCN-AS1 long-noncoding RNA CRISPR-targeting suppresses metastasis in triple-negative breast cancer. Proc Natl Acad Sci U S A 2023; 120:e2215553120. [PMID: 36877839 PMCID: PMC10089184 DOI: 10.1073/pnas.2215553120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 01/23/2023] [Indexed: 03/08/2023] Open
Abstract
Mounting evidence implicates the giant, cytoskeletal protein obscurin (720 to 870 kDa), encoded by the OBSCN gene, in the predisposition and development of breast cancer. Accordingly, prior work has shown that the sole loss of OBSCN from normal breast epithelial cells increases survival and chemoresistance, induces cytoskeletal alterations, enhances cell migration and invasion, and promotes metastasis in the presence of oncogenic KRAS. Consistent with these observations, analysis of Kaplan-Meier Plotter datasets reveals that low OBSCN levels correlate with significantly reduced overall and relapse-free survival in breast cancer patients. Despite the compelling evidence implicating OBSCN loss in breast tumorigenesis and progression, its regulation remains elusive, limiting any efforts to restore its expression, a major challenge given its molecular complexity and gigantic size (~170 kb). Herein, we show that OBSCN-Antisense RNA 1 (OBSCN-AS1), a novel nuclear long-noncoding RNA (lncRNA) gene originating from the minus strand of OBSCN, and OBSCN display positively correlated expression and are downregulated in breast cancer biopsies. OBSCN-AS1 regulates OBSCN expression through chromatin remodeling involving H3 lysine 4 trimethylation enrichment, associated with open chromatin conformation, and RNA polymerase II recruitment. CRISPR-activation of OBSCN-AS1 in triple-negative breast cancer cells effectively and specifically restores OBSCN expression and markedly suppresses cell migration, invasion, and dissemination from three-dimensional spheroids in vitro and metastasis in vivo. Collectively, these results reveal the previously unknown regulation of OBSCN by an antisense lncRNA and the metastasis suppressor function of the OBSCN-AS1/OBSCN gene pair, which may be used as prognostic biomarkers and/or therapeutic targets for metastatic breast cancer.
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Affiliation(s)
- Talia Guardia
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD21201
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, Baltimore, MD21201
| | - Yuqi Zhang
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD21218
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD21218
| | - Keyata N. Thompson
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, Baltimore, MD21201
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD21201
| | - Se Jong Lee
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD21218
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD21218
| | - Stuart S. Martin
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, Baltimore, MD21201
- Department of Physiology, University of Maryland School of Medicine, Baltimore, MD21201
| | - Konstantinos Konstantopoulos
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD21218
- Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD21218
| | - Aikaterini Kontrogianni-Konstantopoulos
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD21201
- Marlene and Stewart Greenebaum Comprehensive Cancer Center, Baltimore, MD21201
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5
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Hu H, Geng Z, Zhang S, Xu Y, Wang Q, Chen S, Zhang B, Sun K, Lu Y. Rare copy number variation analysis identifies disease-related variants in atrioventricular septal defect patients. Front Genet 2023; 14:1075349. [PMID: 36816019 PMCID: PMC9936062 DOI: 10.3389/fgene.2023.1075349] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 01/25/2023] [Indexed: 02/05/2023] Open
Abstract
Atrioventricular septal defect (AVSD) is a deleterious subtype of congenital heart diseases (CHD) characterized by atrioventricular canal defect. The pathogenic genetic changes of AVSD remain elusive, particularly for copy number variation (CNV), a large segment variation of the genome, which is one of the major forms of genetic variants resulting in congenital heart diseases. In the present study, we recruited 150 AVSD cases and 100 healthy subjects as controls for whole exome sequencing (WES). We identified total 4255 rare CNVs using exon Hidden Markov model (XHMM) and screened rare CNVs by eliminating common CNVs based on controls and Database of Genomic Variants (DGV). Each patient contained at least 9 CNVs, and the CNV burden was prominently presented in chromosomes 19,22,21&16. Small CNVs (<500 kb) were frequently observed. By leveraging gene-based burden test, we further identified 20 candidate AVSD-risk genes. Among them, DYRK1A, OBSCN and TTN were presented in the core disease network of CHD and highly and dynamically expressed in the heart during the development, which indicated they possessed the high potency to be AVSD-susceptible genes. These findings not only provided a roadmap for finally unveiling the genetic cause of AVSD, but also provided more resources and proofs for clinical genetics.
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Affiliation(s)
- Huan Hu
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zilong Geng
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shasha Zhang
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yuejuan Xu
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Qingjie Wang
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Sun Chen
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Bing Zhang
- Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China,*Correspondence: Bing Zhang, ; Kun Sun, ; Yanan Lu,
| | - Kun Sun
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China,*Correspondence: Bing Zhang, ; Kun Sun, ; Yanan Lu,
| | - Yanan Lu
- Department of Pediatric Cardiology, Xin Hua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China,*Correspondence: Bing Zhang, ; Kun Sun, ; Yanan Lu,
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6
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Xia T, Lei H, Wang J, He Y, Wang H, Gao L, Qi T, Xiong X, Liu L, Zhu Y. Identification of an ergosterol derivative with anti-melanoma effect from the sponge-derived fungus Pestalotiopsis sp. XWS03F09. Front Microbiol 2022; 13:1008053. [PMCID: PMC9608767 DOI: 10.3389/fmicb.2022.1008053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
It is difficult to treat malignant melanoma because of its high malignancy. New and effective therapies for treating malignant melanoma are urgently needed. Ergosterols are known for specific biological activities and have received widespread attention in cancer therapy. Here, LH-1, a kind of ergosterol from the secondary metabolites of the marine fungus Pestalotiopsis sp., was extracted, isolated, purified, and further investigated the biological activities against melanoma. In vitro experiments, the anti-proliferation effect on tumor cells was detected by MTT and colony formation assay, and the anti-metastatic effect on tumor cells was investigated by wound healing assay and transwell assay. Subcutaneous xenograft models, histopathology, and immunohistochemistry have been used to verify the anti-tumor, toxic, and side effect in vivo. Besides, the anti-tumor mechanism of LH-1 was studied by mRNA sequencing. In vitro, LH-1 could inhibit the proliferation and migration of melanoma cells A375 and B16-F10 in a dose-dependent manner and promote tumor cell apoptosis through the mitochondrial apoptosis pathway. In vivo assays confirmed that LH-1 could suppress melanoma growth by inducing cell apoptosis and reducing cell proliferation, and it did not have any notable toxic effects on normal tissues. LH-1 may play an anti-melanoma role by upregulating OBSCN gene expression. These findings suggest that LH-1 may be a potential for the treatment of melanoma.
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Affiliation(s)
- Tong Xia
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Hui Lei
- School of Pharmacy, Southwest Medical University, Luzhou, China
| | - Jianv Wang
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Yijing He
- Department of Science and Technology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Hailan Wang
- School of Public Health, Southwest Medical University, Luzhou, China
| | - Lanyang Gao
- Department of Science and Technology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
| | - Tingting Qi
- Department of Clinical Pharmacy, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Xia Xiong
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
- Xia Xiong,
| | - Li Liu
- Department of Dermatology, The Affiliated Hospital of Southwest Medical University, Luzhou, China
- Li Liu,
| | - Yongxia Zhu
- Department of Clinical Pharmacy, Sichuan Cancer Hospital and Institute, Sichuan Cancer Center, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
- *Correspondence: Yongxia Zhu,
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7
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A novel missense mutation in obscurin gene in a Chinese consanguineous family with left ventricular noncompaction. J Geriatr Cardiol 2022; 19:531-538. [PMID: 35975021 PMCID: PMC9361159 DOI: 10.11909/j.issn.1671-5411.2022.07.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Left ventricular noncompaction (LVNC) is an increasingly recognised cardiomyopathy of which a significant percentage are genetic in origin. The purpose of the present study was to identify potential pathogenic mutation leading to disease in a Chinese LVNC family. METHODS A 3-generation family affected by LVNC was recruited. Clinical assessments were performed on available family members, with clinical examination, ECG, echocardiography and cardiac MRI. The proband (I-2), the proband's daughter (II-1, affected) and mother (III-1, unaffected) were selected for WGS. Sanger sequencing were performed in all of the 4 surviving family members. RESULTS Combined whole genome sequencing with linkage analysis identified a novel missense mutation in the giant protein obscurin (OBSCN NM_001098623, c.C19063T), as the only plausible disease-causing variant that segregates with disease among the four surviving individuals, with interrogation of the entire genome excluding other potential causes. This c.C19063T missense mutation resulted in p.R6355W in the encoded OBSCN protein. It affected a highly conserved residue in the C terminus of the obscurin-B-like isoform between the PH and STKc domains, which was predicted to affect the function of the protein by different bioinformatics tools. CONCLUSIONS Here we present clinical and genetic evidence implicating the novel R6355W missense mutation in obscurin as the cause of familial LVNC. This expands the spectrum of obscurin's roles in cardiomyopathies. It furthermore highlights that rare obscurin missense variants, currently often ignored or left uninterpreted, should be considered to be relevant for cardiomyopathies and can be identified by the approach presented here. This study also provided new insights into the molecular basis of OBSCN mutation positive LVNC.
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8
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Tuntithavornwat S, Shea DJ, Wong BS, Guardia T, Lee SJ, Yankaskas CL, Zheng L, Kontrogianni-Konstantopoulos A, Konstantopoulos K. Giant obscurin regulates migration and metastasis via RhoA-dependent cytoskeletal remodeling in pancreatic cancer. Cancer Lett 2022; 526:155-167. [PMID: 34826548 PMCID: PMC9427004 DOI: 10.1016/j.canlet.2021.11.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/15/2021] [Accepted: 11/12/2021] [Indexed: 12/23/2022]
Abstract
Obscurins, encoded by the OBSCN gene, are giant cytoskeletal proteins with structural and regulatory roles. Large scale omics analyses reveal that OBSCN is highly mutated across different types of cancer, exhibiting a 5-8% mutation frequency in pancreatic cancer. Yet, the functional role of OBSCN in pancreatic cancer progression and metastasis has to be delineated. We herein show that giant obscurins are highly expressed in normal pancreatic tissues, but their levels are markedly reduced in pancreatic ductal adenocarcinomas. Silencing of giant obscurins in non-tumorigenic Human Pancreatic Ductal Epithelial (HPDE) cells and obscurin-expressing Panc5.04 pancreatic cancer cells induces an elongated, spindle-like morphology and faster cell migration via cytoskeletal remodeling. Specifically, depletion of giant obscurins downregulates RhoA activity, which in turn results in reduced focal adhesion density, increased microtubule growth rate and faster actin dynamics. Although OBSCN knockdown is not sufficient to induce de novo tumorigenesis, it potentiates tumor growth in a subcutaneous implantation model and exacerbates metastasis in a hemispleen murine model of pancreatic cancer metastasis, thereby shortening survival. Collectively, these findings reveal a critical role of giant obscurins as tumor suppressors in normal pancreatic epithelium whose loss of function induces RhoA-dependent cytoskeletal remodeling, and promotes cell migration, tumor growth and metastasis.
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Affiliation(s)
- Soontorn Tuntithavornwat
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Daniel J Shea
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Bin Sheng Wong
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA; Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, USA
| | - Talia Guardia
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine Marlene and Stewart Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA
| | - Se Jong Lee
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Christopher L Yankaskas
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA; Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, USA
| | - Lei Zheng
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Aikaterini Kontrogianni-Konstantopoulos
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine Marlene and Stewart Greenebaum Comprehensive Cancer Center, Baltimore, MD, USA.
| | - Konstantinos Konstantopoulos
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, USA; Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, USA; Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, MD, USA.
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9
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Pierantozzi E, Szentesi P, Paolini C, Dienes B, Fodor J, Oláh T, Colombini B, Rassier DE, Rubino EM, Lange S, Rossi D, Csernoch L, Bagni MA, Reggiani C, Sorrentino V. Impaired Intracellular Ca 2+ Dynamics, M-Band and Sarcomere Fragility in Skeletal Muscles of Obscurin KO Mice. Int J Mol Sci 2022; 23:1319. [PMID: 35163243 PMCID: PMC8835721 DOI: 10.3390/ijms23031319] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 12/16/2022] Open
Abstract
Obscurin is a giant sarcomeric protein expressed in striated muscles known to establish several interactions with other proteins of the sarcomere, but also with proteins of the sarcoplasmic reticulum and costameres. Here, we report experiments aiming to better understand the contribution of obscurin to skeletal muscle fibers, starting with a detailed characterization of the diaphragm muscle function, which we previously reported to be the most affected muscle in obscurin (Obscn) KO mice. Twitch and tetanus tension were not significantly different in the diaphragm of WT and Obscn KO mice, while the time to peak (TTP) and half relaxation time (HRT) were prolonged. Differences in force-frequency and force-velocity relationships and an enhanced fatigability are observed in an Obscn KO diaphragm with respect to WT controls. Voltage clamp experiments show that a sarcoplasmic reticulum's Ca2+ release and SERCA reuptake rates were decreased in muscle fibers from Obscn KO mice, suggesting that an impairment in intracellular Ca2+ dynamics could explain the observed differences in the TTP and HRT in the diaphragm. In partial contrast with previous observations, Obscn KO mice show a normal exercise tolerance, but fiber damage, the altered sarcomere ultrastructure and M-band disarray are still observed after intense exercise.
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Affiliation(s)
- Enrico Pierantozzi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - Péter Szentesi
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Cecilia Paolini
- Department of Neuroscience, Imaging and Clinical Sciences, University Gabriele d’ Annunzio of Chieti, 66100 Chieti, Italy;
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Tamás Oláh
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Barbara Colombini
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy; (B.C.); (M.A.B.)
| | - Dilson E. Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, QC H2W 1S4, Canada;
| | - Egidio Maria Rubino
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - Stephan Lange
- Biomedical Research Facility 2, School of Medicine, University of California, La Jolla, CA 92093, USA;
- Department of Molecular and Clinical Medicine, Institute of Medicine, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Daniela Rossi
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, H-4002 Debrecen, Hungary; (P.S.); (B.D.); (J.F.); (T.O.); (L.C.)
| | - Maria Angela Bagni
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy; (B.C.); (M.A.B.)
| | - Carlo Reggiani
- Department of Biomedical Science, University of Padova, 35121 Padova, Italy;
- Science and Research Center Koper, Institute for Kinesiology Research, 6000 Koper, Slovenia
| | - Vincenzo Sorrentino
- Department of Molecular and Developmental Medicine, Molecular Medicine Section, University of Siena, 53100 Siena, Italy; (E.P.); (E.M.R.); (D.R.)
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10
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Wu G, Liu J, Liu M, Huang Q, Ruan J, Zhang C, Wang D, Sun X, Jiang W, Kang L, Wang J, Song L. Truncating Variants in OBSCN Gene Associated With Disease-Onset and Outcomes of Hypertrophic Cardiomyopathy. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2021; 14:e003401. [PMID: 34601892 DOI: 10.1161/circgen.121.003401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The presence of variants in OBSCN was identified to be linked to hypertrophic cardiomyopathy (HCM), but whether OBSCN truncating variants were associated with HCM remained unknown. METHODS Whole-exome sequencing was performed in 986 patients with HCM and 761 non-HCM controls to search for OBSCN truncating variants, and the result was tested in a replication cohort consisting of 529 patients with HCM and 307 controls. The association of the OBSCN truncating variants with baseline characteristics and prognosis of patients with HCM were ascertained. RESULTS There were 28 qualifying truncating variants in the OBSCN gene detected in 26 (2.6%) patients with HCM and 6 (0.8%) controls. The OBSCN truncating variants were more prevalent in patients with HCM than controls (odds ratio, 3.4, P=0.004). This association was confirmed in the replication cohort (odds ratio, 3.8, P=0.024). The combined effects of the two cohorts estimated the odds ratio to be 3.58 (P<0.001). Patients with or without OBSCN truncating variants shared similar demographic and echocardiographic variables at baseline. During 3.3±2.4 years (4795 patient-years) follow-up, the patients with OBSCN truncating variants were more likely to experience cardiovascular death (adjusted hazard ratio, 3.1 [95% CI, 1.40-6.70], P=0.005) and all-cause death (adjusted hazard ratio, 2.63 [95% CI, 1.21-5.71], P=0.015). CONCLUSIONS Our data indicated that OBSCN truncating variants contributed to the disease-onset of HCM, and increased the risk of malignant events in patients with HCM.
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Affiliation(s)
- Guixin Wu
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jie Liu
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Minghao Liu
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Qiya Huang
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jieyun Ruan
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Channa Zhang
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Dong Wang
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiaolu Sun
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Wen Jiang
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lianming Kang
- Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jizheng Wang
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lei Song
- State Key Laboratory of Cardiovascular Disease (G.W., J.L., Q.H., J.R., C.Z., J.W., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Cardiomyopathy Ward (G.W., J.L., M.L., Q.H., J.R., D.W., X.S., W.J., L.K., L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,National Clinical Research Center of Cardiovascular Diseases (L.S.), Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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11
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Guardia T, Eason M, Kontrogianni-Konstantopoulos A. Obscurin: A multitasking giant in the fight against cancer. Biochim Biophys Acta Rev Cancer 2021; 1876:188567. [PMID: 34015411 PMCID: PMC8349851 DOI: 10.1016/j.bbcan.2021.188567] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 05/03/2021] [Accepted: 05/11/2021] [Indexed: 12/19/2022]
Abstract
Giant obscurins (720-870 kDa), encoded by OBSCN, were originally discovered in striated muscles as cytoskeletal proteins with scaffolding and regulatory roles. Recently though, they have risen to the spotlight as key players in cancer development and progression. Herein, we provide a timely prudent synopsis of the expanse of OBSCN mutations across 16 cancer types. Given the extensive work on OBSCN's role in breast epithelium, we summarize functional studies implicating obscurins as potent tumor suppressors in breast cancer and delve into an in silico analysis of its mutational profile and epigenetic (de)regulation using different dataset platforms and sophisticated computational tools. Lastly, we formally describe the OBSCN-Antisense-RNA-1 gene, which belongs to the long non-coding RNA family and discuss its potential role in modulating OBSCN expression in breast cancer. Collectively, we highlight the escalating involvement of obscurins in cancer biology and outline novel potential mechanisms of OBSCN (de)regulation that warrant further investigation.
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Affiliation(s)
- Talia Guardia
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Matthew Eason
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Aikaterini Kontrogianni-Konstantopoulos
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center, USA.
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12
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Semba RD, Zhang P, Dufresne C, Gao T, Al-Jadaan I, Craven ER, Qian J, Edward DP, Mahale A. Primary angle closure glaucoma is characterized by altered extracellular matrix homeostasis in the iris. Proteomics Clin Appl 2021; 15:e2000094. [PMID: 34240827 DOI: 10.1002/prca.202000094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 06/19/2021] [Accepted: 07/06/2021] [Indexed: 11/10/2022]
Abstract
PURPOSE To characterize the proteome of the iris in primary angle closure glaucoma (PACG). EXPERIMENTAL DESIGN In this cross-sectional study, iris samples were obtained from surgical iridectomy of 48 adults with PACG and five normal controls. Peptides from iris were analysed using liquid chromatography-tandem mass spectrometry on an Orbitrap Q Exactive Plus mass spectrometer. Verification of proteins of interest was conducted using selected reaction monitoring on a triple quadrupole mass spectrometer. The main outcome was proteins with a log2 two-fold difference in expression in iris between PACG and controls. RESULTS There were 3,446 non-redundant proteins identified in human iris, of which 416 proteins were upregulated and 251 proteins were downregulated in PACG compared with controls. Thirty-two upregulated proteins were either components of the extracellular matrix (ECM) (fibrillar collagens, EMILIN-2, fibrinogen, fibronectin, matrilin-2), matricellular proteins (thrombospondin-1), proteins involved in cell-matrix interactions (integrins, laminin, histidine-rich glycoprotein, paxillin), or protease inhibitors known to modulate ECM turnover (α-2 macroglobulin, tissue factor pathway inhibitor 2, papilin). Two giant proteins, titin and obscurin, were up- and down-regulated, respectively, in the iris in PACG compared with controls. CONCLUSIONS AND CLINICAL RELEVANCE This proteomic study shows that ECM composition and homeostasis are altered in the iris in PACG.
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Affiliation(s)
- Richard D Semba
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Pingbo Zhang
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Tianshun Gao
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Earl R Craven
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jiang Qian
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Deepak P Edward
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
| | - Alka Mahale
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
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13
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Qiu J, Wu L, Chang Y, Sun H, Sun J. Alternative splicing transitions associate with emerging atrophy phenotype during denervation-induced skeletal muscle atrophy. J Cell Physiol 2021; 236:4496-4514. [PMID: 33319931 DOI: 10.1002/jcp.30167] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/23/2020] [Accepted: 11/05/2020] [Indexed: 12/25/2022]
Abstract
Alternative splicing (AS) presents a key posttranscriptional regulatory mechanism associated with numerous physiological processes. However, little is known about its role in skeletal muscle atrophy. In this study, we used a rat model of denervated skeletal muscle atrophy and performed RNA-sequencing to analyze transcriptome profiling of tibialis anterior muscle at multiple time points following denervation. We found that AS is a novel mechanism involving muscle atrophy, which is independent changes at the transcript level. Bioinformatics analysis further revealed that AS transitions are associated with the appearance of the atrophic phenotype. Moreover, we found that the inclusion of multiple highly conserved exons of Obscn markedly increased at 3 days after denervation. In addition, we confirmed that this newly transcript inhibited C2C12 cell proliferation and exacerbated myotube atrophy. Finally, our study revealed that a large number of RNA-binding proteins were upregulated when the atrophy phenotype appeared. Our data emphasize the importance of AS in this process.
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Affiliation(s)
- Jiaying Qiu
- Department of Prenatal Screening and Diagnosis Center, Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Affiliated Maternity and Child Health Care Hospital of Nantong University, Nantong University, Nantong, Jiangsu, China
| | - Liucheng Wu
- Laboratory Animal Center, Nantong University, Nantong, China
| | - Yan Chang
- School of Life Sciences, Nantong University, Nantong, Jiangsu, China
| | - Hualin Sun
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - Junjie Sun
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
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14
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Striated Preferentially Expressed Protein Kinase (SPEG) in Muscle Development, Function, and Disease. Int J Mol Sci 2021; 22:ijms22115732. [PMID: 34072258 PMCID: PMC8199188 DOI: 10.3390/ijms22115732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 05/23/2021] [Accepted: 05/25/2021] [Indexed: 02/06/2023] Open
Abstract
Mutations in striated preferentially expressed protein kinase (SPEG), a member of the myosin light chain kinase protein family, are associated with centronuclear myopathy (CNM), cardiomyopathy, or a combination of both. Burgeoning evidence suggests that SPEG plays critical roles in the development, maintenance, and function of skeletal and cardiac muscles. Here we review the genotype-phenotype relationships and the molecular mechanisms of SPEG-related diseases. This review will focus on the progress made toward characterizing SPEG and its interacting partners, and its multifaceted functions in muscle regeneration, triad development and maintenance, and excitation-contraction coupling. We will also discuss future directions that are yet to be investigated including understanding of its tissue-specific roles, finding additional interacting proteins and their relationships. Understanding the basic mechanisms by which SPEG regulates muscle development and function will provide critical insights into these essential processes and help identify therapeutic targets in SPEG-related disorders.
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15
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Binenbaum I, Atamni HAT, Fotakis G, Kontogianni G, Koutsandreas T, Pilalis E, Mott R, Himmelbauer H, Iraqi FA, Chatziioannou AA. Container-aided integrative QTL and RNA-seq analysis of Collaborative Cross mice supports distinct sex-oriented molecular modes of response in obesity. BMC Genomics 2020; 21:761. [PMID: 33143653 PMCID: PMC7640698 DOI: 10.1186/s12864-020-07173-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/21/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND The Collaborative Cross (CC) mouse population is a valuable resource to study the genetic basis of complex traits, such as obesity. Although the development of obesity is influenced by environmental factors, underlying genetic mechanisms play a crucial role in the response to these factors. The interplay between the genetic background and the gene expression pattern can provide further insight into this response, but we lack robust and easily reproducible workflows to integrate genomic and transcriptomic information in the CC mouse population. RESULTS We established an automated and reproducible integrative workflow to analyse complex traits in the CC mouse genetic reference panel at the genomic and transcriptomic levels. We implemented the analytical workflow to assess the underlying genetic mechanisms of host susceptibility to diet induced obesity and integrated these results with diet induced changes in the hepatic gene expression of susceptible and resistant mice. Hepatic gene expression differs significantly between obese and non-obese mice, with a significant sex effect, where male and female mice exhibit different responses and coping mechanisms. CONCLUSION Integration of the data showed that different genes but similar pathways are involved in the genetic susceptibility and disturbed in diet induced obesity. Genetic mechanisms underlying susceptibility to high-fat diet induced obesity are different in female and male mice. The clear distinction we observed in the systemic response to the high-fat diet challenge and to obesity between male and female mice points to the need for further research into distinct sex-related mechanisms in metabolic disease.
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Affiliation(s)
- Ilona Binenbaum
- Division of Pediatric Hematology-Oncology, First Department of Pediatrics, National and Kapodistrian University of Athens, Athens, Greece
- Department of Biology, University of Patras, Patras, Greece
| | - Hanifa Abu-Toamih Atamni
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Georgios Fotakis
- Division of Bioinformatics, Medical University of Innsbruck, Innsbruck, Austria
- e-NIOS PC, Kallithea, Athens, Greece
| | - Georgia Kontogianni
- Center of Systems Biology, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Theodoros Koutsandreas
- e-NIOS PC, Kallithea, Athens, Greece
- Center of Systems Biology, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Eleftherios Pilalis
- e-NIOS PC, Kallithea, Athens, Greece
- Center of Systems Biology, Biomedical Research Foundation of the Academy of Athens, Athens, Greece
| | - Richard Mott
- Department of Genetics, University College of London, London, UK
| | - Heinz Himmelbauer
- Institute of Computational Biology, Department of Biotechnology, University of Life Sciences and Natural Resources, Vienna (BOKU), Vienna, Austria
- Centre for Genomic Regulation (CRG), Barcelona, Spain
| | - Fuad A Iraqi
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
| | - Aristotelis A Chatziioannou
- e-NIOS PC, Kallithea, Athens, Greece.
- Center of Systems Biology, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
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16
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Grogan A, Coleman A, Joca H, Granzier H, Russel MW, Ward CW, Kontrogianni-Konstantopoulos A. Deletion of obscurin immunoglobulin domains Ig58/59 leads to age-dependent cardiac remodeling and arrhythmia. Basic Res Cardiol 2020; 115:60. [PMID: 32910221 PMCID: PMC9302192 DOI: 10.1007/s00395-020-00818-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 08/06/2020] [Indexed: 12/23/2022]
Abstract
Obscurin comprises a family of giant modular proteins that play key structural and regulatory roles in striated muscles. Immunoglobulin domains 58/59 (Ig58/59) of obscurin mediate binding to essential modulators of muscle structure and function, including canonical titin, a smaller splice variant of titin, termed novex-3, and phospholamban (PLN). Importantly, missense mutations localized within the obscurin-Ig58/59 region that affect binding to titins and/or PLN have been linked to the development of myopathy in humans. To elucidate the pathophysiological role of this region, we generated a constitutive deletion mouse model, Obscn-ΔIg58/59, that expresses obscurin lacking Ig58/59, and determined the consequences of this manipulation on cardiac morphology and function under conditions of acute stress and through the physiological process of aging. Our studies show that young Obscn-ΔIg58/59 mice are susceptible to acute β-adrenergic stress. Moreover, sedentary Obscn-ΔIg58/59 mice develop left ventricular hypertrophy that progresses to dilation, contractile impairment, atrial enlargement, and arrhythmia as a function of aging with males being more affected than females. Experiments in ventricular cardiomyocytes revealed altered Ca2+ cycling associated with changes in the expression and/or phosphorylation levels of major Ca2+ cycling proteins, including PLN, SERCA2, and RyR2. Taken together, our work demonstrates that obscurin-Ig58/59 is an essential regulatory module in the heart and its deletion leads to age- and sex-dependent cardiac remodeling, ventricular dilation, and arrhythmia due to deregulated Ca2+ cycling.
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MESH Headings
- Action Potentials
- Age Factors
- Animals
- Arrhythmias, Cardiac/enzymology
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/pathology
- Arrhythmias, Cardiac/physiopathology
- Calcium Signaling
- Calcium-Binding Proteins/metabolism
- Female
- Gene Deletion
- Heart Rate
- Hypertrophy, Left Ventricular/enzymology
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/pathology
- Hypertrophy, Left Ventricular/physiopathology
- Immunoglobulin Domains
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Myocytes, Cardiac/enzymology
- Myocytes, Cardiac/pathology
- Phosphorylation
- Protein Serine-Threonine Kinases/deficiency
- Protein Serine-Threonine Kinases/genetics
- Rho Guanine Nucleotide Exchange Factors/deficiency
- Rho Guanine Nucleotide Exchange Factors/genetics
- Ryanodine Receptor Calcium Release Channel/metabolism
- Sarcoplasmic Reticulum Calcium-Transporting ATPases/metabolism
- Sedentary Behavior
- Sex Factors
- Ventricular Dysfunction, Left/enzymology
- Ventricular Dysfunction, Left/genetics
- Ventricular Dysfunction, Left/pathology
- Ventricular Dysfunction, Left/physiopathology
- Ventricular Function, Left
- Ventricular Remodeling
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Andrew Coleman
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Humberto Joca
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Henk Granzier
- Department of Physiology, University of Arizona College of Medicine, Tucson, AZ, 85724, USA
| | - Mark W Russel
- Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Christopher W Ward
- Department of Orthopedics, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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17
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Grogan A, Tsakiroglou P, Kontrogianni-Konstantopoulos A. Double the trouble: giant proteins with dual kinase activity in the heart. Biophys Rev 2020; 12:1019-1029. [PMID: 32638332 DOI: 10.1007/s12551-020-00715-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/02/2020] [Indexed: 12/12/2022] Open
Abstract
Obscurin and its homolog, striated muscle preferentially expressed gene (SPEG), constitute a unique group of proteins abundantly expressed in striated muscles that contain two tandemly arranged MLCK-like kinases. The physiological significance of the dual kinase motifs is largely understudied; however, a collection of recent studies characterizing their binding interactions, putative targets, and disease-linked mutations have begun to shed light on their potential roles in muscle pathophysiology. Specifically, obscurin kinase 1 is proposed to regulate cardiomyocyte adhesion via phosphorylating N-cadherin, whereas SPEG kinases 1 and 2 regulate Ca2+ cycling by phosphorylating junctophilin-2 and the sarcoendoplasmic Ca2+ ATPase 2 (SERCA2). Herein, we review what is currently known regarding the potential substrates, physiological roles, and disease associations of obscurin and SPEG tandem kinase domains and provide future directions that have yet to be investigated.
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD, 21201, USA
| | - Panagiotis Tsakiroglou
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St, Baltimore, MD, 21201, USA
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18
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Gong M, Wang Z, Liu Y, Li W, Ye S, Zhu J, Zhang H, Wang J, He K. A transcriptomic analysis of Nsmce1 overexpression in mouse hippocampal neuronal cell by RNA sequencing. Funct Integr Genomics 2019; 20:459-470. [PMID: 31792732 DOI: 10.1007/s10142-019-00728-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 10/10/2019] [Accepted: 11/06/2019] [Indexed: 02/07/2023]
Abstract
Mouse Nsmce1 gene is the homolog of non-structural maintenance of chromosomes element 1 (NSE1) that is mainly involved in maintenance of genome integrity, DNA damage response, and DNA repair. Defective DNA repair may cause neurological disorders such as Alzheimer's disease (AD). So far, there is no direct evidence for the correlation between Nsmce1 and AD. In order to explore the function of Nsmce1 in the regulation of nervous system, we have overexpressed or knocked down Nsmce1 in the mouse hippocampal neuronal cells (MHNCs) HT-22 and detected its regulation of AD marker genes as well as cell proliferation. The results showed that the expression of App, Bace2, and Mapt could be inhibited by Nsmce1 overexpression and activated by the knockdown of Nsmce1. Moreover, the HT-22 cell proliferation ability could be promoted by Nsmce1 overexpression and inhibited by knockdown of Nsmce1. Furthermore, we performed a transcriptomics study by RNA sequencing (RNA-seq) to evaluate and quantify the gene expression profiles in response to the overexpression of Nsmce1 in HT-22 cells. As a result, 224 significantly dysregulated genes including 83 upregulated and 141 downregulated genes were identified by the comparison of Nsmce1 /+ to WT cells, which were significantly enriched in several Gene Ontology (GO) terms and pathways. In addition, the complexity of the alternative splicing (AS) landscape was increased by Nsmce1 overexpression in HT-22 cells. Thousands of AS events were identified to be mainly involved in the pathway of ubiquitin-mediated proteolysis (UMP) as well as 3 neurodegenerative diseases including AD. The protein-protein interaction network was reconstructed to show top 10 essential genes regulated by Nsmce1. Our sequencing data is available in the Gene Expression Omnibus (GEO) database with accession number as GSE113436. These results may provide some evidence of molecular and cellular functions of Nsmce1 in MHNCs.
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Affiliation(s)
- Mengting Gong
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, 230601, Anhui, China
| | - Zhen Wang
- Department of Genetics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Yanjun Liu
- Department of Biostatistics, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Wenxing Li
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China
- Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650204, Yunnan, China
| | - Shoudong Ye
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, 230601, Anhui, China
- Department of Biostatistics, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Jie Zhu
- Department of Biostatistics, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Hui Zhang
- Department of Biostatistics, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Jing Wang
- Department of Biostatistics, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China
| | - Kan He
- Center for Stem Cell and Translational Medicine, School of Life Sciences, Anhui University, 111 Jiulong Road, Hefei, 230601, Anhui, China.
- Department of Biostatistics, School of Life Sciences, Anhui University, Hefei, 230601, Anhui, China.
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19
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Dasbiswas K, Hu S, Schnorrer F, Safran SA, Bershadsky AD. Ordering of myosin II filaments driven by mechanical forces: experiments and theory. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2017.0114. [PMID: 29632266 DOI: 10.1098/rstb.2017.0114] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2017] [Indexed: 12/27/2022] Open
Abstract
Myosin II filaments form ordered superstructures in both cross-striated muscle and non-muscle cells. In cross-striated muscle, myosin II (thick) filaments, actin (thin) filaments and elastic titin filaments comprise the stereotypical contractile units of muscles called sarcomeres. Linear chains of sarcomeres, called myofibrils, are aligned laterally in registry to form cross-striated muscle cells. The experimentally observed dependence of the registered organization of myofibrils on extracellular matrix elasticity has been proposed to arise from the interactions of sarcomeric contractile elements (considered as force dipoles) through the matrix. Non-muscle cells form small bipolar filaments built of less than 30 myosin II molecules. These filaments are associated in registry forming superstructures ('stacks') orthogonal to actin filament bundles. Formation of myosin II filament stacks requires the myosin II ATPase activity and function of the actin filament crosslinking, polymerizing and depolymerizing proteins. We propose that the myosin II filaments embedded into elastic, intervening actin network (IVN) function as force dipoles that interact attractively through the IVN. This is in analogy with the theoretical picture developed for myofibrils where the elastic medium is now the actin cytoskeleton itself. Myosin stack formation in non-muscle cells provides a novel mechanism for the self-organization of the actin cytoskeleton at the level of the entire cell.This article is part of the theme issue 'Self-organization in cell biology'.
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Affiliation(s)
- Kinjal Dasbiswas
- James Franck Institute, University of Chicago, Chicago, IL 60637, USA
| | - Shiqiong Hu
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Republic of Singapore.,Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Frank Schnorrer
- Aix Marseille University, CNRS, IBDM, 13288 Marseille, France
| | - Samuel A Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Alexander D Bershadsky
- Mechanobiology Institute, National University of Singapore, Singapore 117411, Republic of Singapore .,Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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20
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Whitley JA, Ex-Willey AM, Marzolf DR, Ackermann MA, Tongen AL, Kokhan O, Wright NT. Obscurin is a semi-flexible molecule in solution. Protein Sci 2019; 28:717-726. [PMID: 30666746 DOI: 10.1002/pro.3578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 01/14/2019] [Indexed: 01/10/2023]
Abstract
Obscurin, a giant modular cytoskeletal protein, is comprised mostly of tandem immunoglobulin-like (Ig-like) domains. This architecture allows obscurin to connect distal targets within the cell. The linkers connecting the Ig domains are usually short (3-4 residues). The physical effect arising from these short linkers is not known; such linkers may lead to a stiff elongated molecule or, conversely, may lead to a more compact and dynamic structure. In an effort to better understand how linkers affect obscurin flexibility, and to better understand the physical underpinnings of this flexibility, here we study the structure and dynamics of four representative sets of dual obscurin Ig domains using experimental and computational techniques. We find in all cases tested that tandem obscurin Ig domains interact at the poles of each domain and tend to stay relatively extended in solution. NMR, SAXS, and MD simulations reveal that while tandem domains are elongated, they also bend and flex significantly. By applying this behavior to a simplified model, it becomes apparent obscurin can link targets more than 200 nm away. However, as targets get further apart, obscurin begins acting as a spring and requires progressively more energy to further elongate.
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Affiliation(s)
- Jacob A Whitley
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Aidan M Ex-Willey
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807.,Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, Ohio, 43210
| | - Daniel R Marzolf
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Maegen A Ackermann
- Department of Physiology and Cell Biology, Wexner Medical Center, Ohio State University, Columbus, Ohio, 43210
| | - Anthony L Tongen
- Department of Mathematics and Statistics, James Madison University, Harrisonburg, Virginia, 22807
| | - Oleksandr Kokhan
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, Virginia, 22807
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21
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Grogan A, Kontrogianni-Konstantopoulos A. Unraveling obscurins in heart disease. Pflugers Arch 2018; 471:735-743. [PMID: 30099631 DOI: 10.1007/s00424-018-2191-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 08/01/2018] [Indexed: 12/18/2022]
Abstract
Obscurins, expressed from the single OBSCN gene, are a family of giant, modular, cytoskeletal proteins that play key structural and regulatory roles in striated muscles. They were first implicated in the development of heart disease in 2007 when two missense mutations were found in a patient diagnosed with hypertrophic cardiomyopathy (HCM). Since then, the discovery of over a dozen missense, frameshift, and splicing mutations that are linked to various forms of cardiomyopathy, including HCM, dilated cardiomyopathy (DCM), and left ventricular non-compaction (LVNC), has highlighted OBSCN as a potential disease-causing gene. At this time, the functional consequences of the identified mutations remain largely elusive, and much work has yet to be done to characterize the disease mechanisms of pathological OBSCN variants. Herein, we describe the OBSCN mutations known to date, discuss their potential impact on disease development, and provide future directions in order to better understand the involvement of obscurins in heart disease.
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Affiliation(s)
- Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St., Baltimore, MD, 21201, USA
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22
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Wang L, Geist J, Grogan A, Hu LYR, Kontrogianni-Konstantopoulos A. Thick Filament Protein Network, Functions, and Disease Association. Compr Physiol 2018; 8:631-709. [PMID: 29687901 PMCID: PMC6404781 DOI: 10.1002/cphy.c170023] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Sarcomeres consist of highly ordered arrays of thick myosin and thin actin filaments along with accessory proteins. Thick filaments occupy the center of sarcomeres where they partially overlap with thin filaments. The sliding of thick filaments past thin filaments is a highly regulated process that occurs in an ATP-dependent manner driving muscle contraction. In addition to myosin that makes up the backbone of the thick filament, four other proteins which are intimately bound to the thick filament, myosin binding protein-C, titin, myomesin, and obscurin play important structural and regulatory roles. Consistent with this, mutations in the respective genes have been associated with idiopathic and congenital forms of skeletal and cardiac myopathies. In this review, we aim to summarize our current knowledge on the molecular structure, subcellular localization, interacting partners, function, modulation via posttranslational modifications, and disease involvement of these five major proteins that comprise the thick filament of striated muscle cells. © 2018 American Physiological Society. Compr Physiol 8:631-709, 2018.
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Affiliation(s)
- Li Wang
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
| | - Li-Yen R. Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Maryland, USA
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23
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Shriver M, Marimuthu S, Paul C, Geist J, Seale T, Konstantopoulos K, Kontrogianni-Konstantopoulos A. Giant obscurins regulate the PI3K cascade in breast epithelial cells via direct binding to the PI3K/p85 regulatory subunit. Oncotarget 2018; 7:45414-45428. [PMID: 27323778 PMCID: PMC5216731 DOI: 10.18632/oncotarget.9985] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/29/2016] [Indexed: 01/22/2023] Open
Abstract
Obscurins are a family of giant cytoskeletal proteins, originally identified in striated muscles where they have structural and regulatory roles. We recently showed that obscurins are abundantly expressed in normal breast epithelial cells where they play tumor and metastasis suppressing roles, but are nearly lost from advanced stage breast cancer biopsies. Consistent with this, loss of giant obscurins from breast epithelial cells results in enhanced survival and growth, epithelial to mesenchymal transition (EMT), and increased cell migration and invasion in vitro and in vivo. In the current study, we demonstrate that loss of giant obscurins from breast epithelial cells is associated with significantly increased phosphorylation and subsequent activation of the PI3K signaling cascade, including activation of AKT, a key regulator of tumorigenesis and metastasis. Pharmacological and molecular inhibition of the PI3K pathway in obscurin-depleted breast epithelial cells results in reversal of EMT, (re)formation of cell-cell junctions, diminished mammosphere formation, and decreased cell migration and invasion. Co-immunoprecipitation, pull-down, and surface plasmon resonance assays revealed that obscurins are in a complex with the PI3K/p85 regulatory subunit, and that their association is direct and mediated by the obscurin-PH domain and the PI3K/p85-SH3 domain with a KD of ~50 nM. We therefore postulate that giant obscurins act upstream of the PI3K cascade in normal breast epithelial cells, regulating its activation through binding to the PI3K/p85 regulatory subunit.
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Affiliation(s)
- Marey Shriver
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Saravanakumar Marimuthu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Colin Paul
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.,Johns Hopkins Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, USA.,Johns Hopkins Physical Sciences-Oncology Center, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Janelle Geist
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Tessa Seale
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Konstantinos Konstantopoulos
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.,Johns Hopkins Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD 21218, USA.,Johns Hopkins Physical Sciences-Oncology Center, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Aikaterini Kontrogianni-Konstantopoulos
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine,Baltimore, MD 21201, USA.,University of Maryland School of Medicine, Marlene and Stewart Greenebaum National Cancer Institute Cancer Center, Baltimore, MD 21201, USA
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24
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Ackermann MA, Shriver M, Perry NA, Hu LYR, Kontrogianni-Konstantopoulos A. Correction: Obscurins: Goliaths and Davids Take over Non-Muscle Tissues. PLoS One 2018; 13:e0190842. [PMID: 29298356 PMCID: PMC5752041 DOI: 10.1371/journal.pone.0190842] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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25
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Rajendran BK, Deng CX. A comprehensive genomic meta-analysis identifies confirmatory role of OBSCN gene in breast tumorigenesis. Oncotarget 2017; 8:102263-102276. [PMID: 29254242 PMCID: PMC5731952 DOI: 10.18632/oncotarget.20404] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 07/26/2017] [Indexed: 12/15/2022] Open
Abstract
The giant multifunctional protein "OBSCURIN" is encoded by OBSCN gene and is mostly expressed in cardiac and other skeletal muscles responsible for myofibrils organization. Loss of OBSCURIN affects the entire downstream pathway proteins vital for various cellular functions including cell integration and cell adhesion. The OBSCN gene mutations are more frequently observed in various muscular diseases, and cancers. Nevertheless, the direct role of OBSCN in tumorigenesis remains elusive. Interestingly, in clinical breast cancer samples a significant number of function changing mutations have been identified in OBSCN gene. In this study, we identified a significant role of OBSCN by conducting an integrative analysis of copy number alterations, functional mutations, gene methylation and expression data from various BRCA cancer projects data available on cBioPortal and TCGA firebrowse portal. Finally, we carried out genetic network analysis, which revealed that OBSCN gene plays a significant role in GPCR, RAS, p75 or Wnt signaling pathways. Similarly, OBSCN gene interacts with many cancer-associated genes involved in breast tumorigenesis. The OBSCN gene probably regulates breast cancer progression and metastasis and the prognostic molecular signatures such as copy number alterations and gene expression of OBSCN may serve as a tool to identify breast tumorigenesis and metastasis.
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Affiliation(s)
- Barani Kumar Rajendran
- Cancer Research Centre, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Chu-Xia Deng
- Cancer Research Centre, Faculty of Health Sciences, University of Macau, Macau SAR, China
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26
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Ackermann MA, King B, Lieberman NAP, Bobbili PJ, Rudloff M, Berndsen CE, Wright NT, Hecker PA, Kontrogianni-Konstantopoulos A. Novel obscurins mediate cardiomyocyte adhesion and size via the PI3K/AKT/mTOR signaling pathway. J Mol Cell Cardiol 2017; 111:27-39. [PMID: 28826662 PMCID: PMC5694667 DOI: 10.1016/j.yjmcc.2017.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 08/02/2017] [Accepted: 08/03/2017] [Indexed: 12/29/2022]
Abstract
The intercalated disc of cardiac muscle embodies a highly-ordered, multifunctional network, essential for the synchronous contraction of the heart. Over 200 known proteins localize to the intercalated disc. The challenge now lies in their characterization as it relates to the coupling of neighboring cells and whole heart function. Using molecular, biochemical and imaging techniques, we characterized for the first time two small obscurin isoforms, obscurin-40 and obscurin-80, which are enriched at distinct locations of the intercalated disc. Both proteins bind specifically and directly to select phospholipids via their pleckstrin homology (PH) domain. Overexpression of either isoform or the PH-domain in cardiomyocytes results in decreased cell adhesion and size via reduced activation of the PI3K/AKT/mTOR pathway that is intimately linked to cardiac hypertrophy. In addition, obscurin-80 and obscurin-40 are significantly reduced in acute (myocardial infarction) and chronic (pressure overload) murine cardiac-stress models underscoring their key role in maintaining cardiac homeostasis. Our novel findings implicate small obscurins in the maintenance of cardiomyocyte size and coupling, and the development of heart failure by antagonizing the PI3K/AKT/mTOR pathway.
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Affiliation(s)
- Maegen A Ackermann
- Department of Biochemistry and Molecular Biology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States; Department of Physiology and Cell Biology, Wexner College of Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, United States.
| | - Brendan King
- Department of Biochemistry and Molecular Biology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States
| | - Nicole A P Lieberman
- Department of Biochemistry and Molecular Biology, University of Maryland, School of Medicine, Baltimore, MD 21201, United States
| | - Prameela J Bobbili
- Department of Physiology and Cell Biology, Wexner College of Medicine, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, United States
| | - Michael Rudloff
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, United States
| | - Christopher E Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, United States
| | - Nathan T Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, United States
| | - Peter A Hecker
- Division of Cardiology and Department of Medicine, University of Maryland, Baltimore, MD 20201, United States
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27
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Stroka KM, Wong BS, Shriver M, Phillip JM, Wirtz D, Kontrogianni-Konstantopoulos A, Konstantopoulos K. Loss of giant obscurins alters breast epithelial cell mechanosensing of matrix stiffness. Oncotarget 2017; 8:54004-54020. [PMID: 28903319 PMCID: PMC5589558 DOI: 10.18632/oncotarget.10997] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 07/20/2016] [Indexed: 01/21/2023] Open
Abstract
Obscurins are a family of RhoGEF-containing proteins with tumor and metastasis suppressing roles in breast epithelium. Downregulation of giant obscurins in normal breast epithelial cells leads to reduced levels of active RhoA and of its downstream effectors. Herein, we elucidate how depletion of giant obscurins affects the response of breast epithelial cells to changes in the mechanical properties of the microenvironment. We find that knockdown of obscurins increases cell morphodynamics, migration speed, and diffusivity on polyacrylamide gels of ≥ 1 kPa, presumably by decreasing focal adhesion area and density as well as cell traction forces. Depletion of obscurins also increases cell mechanosensitivity on soft (0.4-4 kPa) surfaces. Similar to downregulation of obscurins, pharmacological inhibition of Rho kinase in breast epithelial cells increases migration and morphodynamics, suggesting that suppression of Rho kinase activity following obscurin knockdown can account for alterations in morphodynamics and migration. In contrast, inhibition of myosin light chain kinase reduces morphodynamics and migration, suggesting that temporal changes in cell shape are required for efficient migration. Collectively, downregulation of giant obscurins facilitates cell migration through heterogeneous microenvironments of varying stiffness by altering cell mechanobiology.
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Affiliation(s)
- Kimberly M. Stroka
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, 20742, USA
| | - Bin Sheng Wong
- Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Johns Hopkins Physical Sciences-Oncology Center, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Marey Shriver
- University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, Baltimore, MD, 21201, USA
| | - Jude M. Phillip
- Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Johns Hopkins Physical Sciences-Oncology Center, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Denis Wirtz
- Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Johns Hopkins Physical Sciences-Oncology Center, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Aikaterini Kontrogianni-Konstantopoulos
- University of Maryland School of Medicine, Department of Biochemistry and Molecular Biology, Baltimore, MD, 21201, USA
- University of Maryland School of Medicine, Marlene and Stewart Greenebaum National Cancer Institute Cancer Center, Baltimore, MD, 21201, USA
| | - Konstantinos Konstantopoulos
- Johns Hopkins Institute for NanoBioTechnology, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Johns Hopkins Physical Sciences-Oncology Center, The Johns Hopkins University, Baltimore, MD, 21218, USA
- Department of Chemical and Biomolecular Engineering, The Johns Hopkins University, Baltimore, MD, 21218, USA
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28
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Randazzo D, Pierantozzi E, Rossi D, Sorrentino V. The potential of obscurin as a therapeutic target in muscle disorders. Expert Opin Ther Targets 2017; 21:897-910. [DOI: 10.1080/14728222.2017.1361931] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Davide Randazzo
- Light Imaging Section, Office of Science and Technology, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda
| | - Enrico Pierantozzi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Daniela Rossi
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Vincenzo Sorrentino
- Molecular Medicine Section, Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
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29
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Hu LYR, Ackermann MA, Hecker PA, Prosser BL, King B, O’Connell KA, Grogan A, Meyer LC, Berndsen CE, Wright NT, Jonathan Lederer W, Kontrogianni-Konstantopoulos A. Deregulated Ca 2+ cycling underlies the development of arrhythmia and heart disease due to mutant obscurin. SCIENCE ADVANCES 2017; 3:e1603081. [PMID: 28630914 PMCID: PMC5462502 DOI: 10.1126/sciadv.1603081] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 04/17/2017] [Indexed: 05/05/2023]
Abstract
Obscurins are cytoskeletal proteins with structural and regulatory roles encoded by OBSCN. Mutations in OBSCN are associated with the development of hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Specifically, the R4344Q mutation present in immunoglobulin domain 58 (Ig58) was the first to be linked with the development of HCM. To assess the effects of R4344Q in vivo, we generated the respective knock-in mouse model. Mutant obscurins are expressed and incorporated normally into sarcomeres. The expression patterns of sarcomeric and Ca2+-cycling proteins are unaltered in sedentary 1-year-old knock-in myocardia, with the exception of sarco/endoplasmic reticulum Ca2+ adenosine triphosphatase 2 (SERCA2) and pentameric phospholamban whose levels are significantly increased and decreased, respectively. Isolated cardiomyocytes from 1-year-old knock-in hearts exhibit increased Ca2+-transients and Ca2+-load in the sarcoplasmic reticulum and faster contractility kinetics. Moreover, sedentary 1-year-old knock-in animals develop tachycardia accompanied by premature ventricular contractions, whereas 2-month-old knock-in animals subjected to pressure overload develop a DCM-like phenotype. Structural analysis revealed that the R4344Q mutation alters the distribution of electrostatic charges over the Ig58 surface, thus interfering with its binding capabilities. Consistent with this, wild-type Ig58 interacts with phospholamban modestly, and this interaction is markedly enhanced in the presence of R4344Q. Together, our studies demonstrate that under sedentary conditions, the R4344Q mutation results in Ca2+ deregulation and spontaneous arrhythmia, whereas in the presence of chronic, pathological stress, it leads to cardiac remodeling and dilation. We postulate that enhanced binding between mutant obscurins and phospholamban leads to SERCA2 disinhibition, which may underlie the observed pathological alterations.
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Affiliation(s)
- Li-Yen R. Hu
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Maegen A. Ackermann
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Peter A. Hecker
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Benjamin L. Prosser
- Department of Physiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
- Department of Physiology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Brendan King
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Kelly A. O’Connell
- Division of Cardiovascular Medicine, Department of Medicine, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Alyssa Grogan
- Department of Biochemistry and Molecular Biology, University of Maryland, Baltimore, Baltimore, MD 21201, USA
| | - Logan C. Meyer
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Christopher E. Berndsen
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - Nathan T. Wright
- Department of Chemistry and Biochemistry, James Madison University, Harrisonburg, VA 22807, USA
| | - W. Jonathan Lederer
- Department of Physiology, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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Abstract
The inherited cardiomyopathies, hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM) and left ventricular non-compaction (LVNC), have been frequently associated with mutations in sarcomeric proteins. In recent years, advances in DNA sequencing technology has allowed the study of the giant proteins of the sarcomere, such as titin and nebulin. Obscurin has been somewhat neglected in these studies, largely because its functional role is far from clear, although there was an isolated report in 2007 of obscurin mutations associated with HCM. Recently, whole exome sequencing methodology (WES) has been used to address mutations in OBSCN, the gene for obscurin, and OBSCN variants were found to be relatively common in inherited cardiomyopathies. In different studies, 5 OBSCN unique variants have been found in a group of 30 end-stage failing hearts, 6 OBSCN unique variants in 74 HCM cases and 3 OBSCN unique variants in 10 LVNC patients. As yet, the number of known potentially disease-causing OBSCN variants is quite small. The reason for this is that mutations in the OBSCN gene have not been recognised as potentially disease-causing until recently, and were not included in large-scale genetic surveys. OBSCN mutations may be causative of HCM, DCM and LVNC and other cardiomyopathies, or they may work in concert with other variants in the same or other genes to initiate the pathology. Currently, the function of obscurin is not well understood, but we anticipate that many more OBSCN variants linked to cardiomyopathy will be found when the large cohorts of patient sequences available are tested. It is to be hoped that the establishment of the importance of obscurin in pathology will stimulate a thorough investigation of obscurin function.
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31
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Abstract
The giant multi-functional striated muscle protein titin is the third most abundant muscle protein after myosin and actin. Titin plays a pivotal role in myocardial passive stiffness, structural integrity and stress-initiated signaling pathways. The complete sequence of the human titin gene contains three isoform-specific mutually exclusive exons [termed novel exons (novex)] coding for the I-band sequence, named novex-1 (exon 45), novex-2 (exon 46) and novex-3 (exon 48). Transcripts containing either the novex-1 or novex-2 exons code for the novex-1 and novex-2 titin isoforms. The novex-3 transcript contains a stop codon and polyA tail signal, resulting in an unusually small (∼700 kDa) isoform, referred to as novex-3 titin. This 'tiny titin' isoform extends from the Z-disc (N-terminus) to novex-3 (C-terminus) and is expressed in all striated muscles. Biochemical analysis of novex-3 titin in cardiomyocytes shows that obscurin, a vertebrate muscle protein, binds to novex-3 titin. The novex-3/obscurin complex localizes to the Z-disc region and may regulate calcium, and SH3- and GTPase-associated myofibrillar signaling pathways. Therefore, novex-3 titin could be involved in stress-initiated sarcomeric restructuring.
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32
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Manring HR, Carter OA, Ackermann MA. Obscure functions: the location-function relationship of obscurins. Biophys Rev 2017; 9:245-258. [PMID: 28510116 DOI: 10.1007/s12551-017-0254-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 03/05/2017] [Indexed: 12/18/2022] Open
Abstract
The obscurin family of polypeptides is essential for normal striated muscle function and contributes to the pathogenesis of fatal diseases, including cardiomyopathies and cancers. The single mammalian obscurin gene, OBSCN, gives rise to giant (∼800 kDa) and smaller (∼40-500 kDa) proteins that are composed of tandem adhesion and signaling motifs. Mammalian obscurin proteins are expressed in a variety of cell types, including striated muscles, and localize to distinct subcellular compartments where they contribute to diverse cellular processes. Obscurin homologs in Caenorhabditis elegans and Drosophila possess a similar domain architecture and are also expressed in striated muscles. The long sought after question, "what does obscurin do?" is complex and cannot be addressed without taking into consideration the subcellular distribution of these proteins and local isoform concentration. Herein, we present an overview of the functions of obscurins and begin to define the intricate relationship between their subcellular distributions and functions in striated muscles.
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Affiliation(s)
- Heather R Manring
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA
| | - Olivia A Carter
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA.,Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA
| | - Maegen A Ackermann
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA. .,Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Ohio State University, Columbus, OH, 43210, USA.
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33
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Rowland TJ, Graw SL, Sweet ME, Gigli M, Taylor MR, Mestroni L. Obscurin Variants in Patients With Left Ventricular Noncompaction. J Am Coll Cardiol 2016; 68:2237-2238. [PMID: 27855815 PMCID: PMC5896764 DOI: 10.1016/j.jacc.2016.08.052] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/04/2016] [Accepted: 08/09/2016] [Indexed: 10/20/2022]
Affiliation(s)
| | | | | | | | - Matthew R.G. Taylor
- Cardiovascular Institute and Adult Medical Genetics Program, University of Colorado Denver, 12700 East 19th Avenue, F442, Aurora, Colorado 80045,
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34
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Hsieh P, Veeramah KR, Lachance J, Tishkoff SA, Wall JD, Hammer MF, Gutenkunst RN. Whole-genome sequence analyses of Western Central African Pygmy hunter-gatherers reveal a complex demographic history and identify candidate genes under positive natural selection. Genome Res 2016; 26:279-90. [PMID: 26888263 PMCID: PMC4772011 DOI: 10.1101/gr.192971.115] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 01/07/2016] [Indexed: 12/20/2022]
Abstract
African Pygmies practicing a mobile hunter-gatherer lifestyle are phenotypically and genetically diverged from other anatomically modern humans, and they likely experienced strong selective pressures due to their unique lifestyle in the Central African rainforest. To identify genomic targets of adaptation, we sequenced the genomes of four Biaka Pygmies from the Central African Republic and jointly analyzed these data with the genome sequences of three Baka Pygmies from Cameroon and nine Yoruba famers. To account for the complex demographic history of these populations that includes both isolation and gene flow, we fit models using the joint allele frequency spectrum and validated them using independent approaches. Our two best-fit models both suggest ancient divergence between the ancestors of the farmers and Pygmies, 90,000 or 150,000 yr ago. We also find that bidirectional asymmetric gene flow is statistically better supported than a single pulse of unidirectional gene flow from farmers to Pygmies, as previously suggested. We then applied complementary statistics to scan the genome for evidence of selective sweeps and polygenic selection. We found that conventional statistical outlier approaches were biased toward identifying candidates in regions of high mutation or low recombination rate. To avoid this bias, we assigned P-values for candidates using whole-genome simulations incorporating demography and variation in both recombination and mutation rates. We found that genes and gene sets involved in muscle development, bone synthesis, immunity, reproduction, cell signaling and development, and energy metabolism are likely to be targets of positive natural selection in Western African Pygmies or their recent ancestors.
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Affiliation(s)
- PingHsun Hsieh
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA
| | - Krishna R Veeramah
- Arizona Research Laboratories Division of Biotechnology, University of Arizona, Tucson, Arizona 85721, USA; Department of Ecology and Evolution, Stony Brook University, Stony Brook, New York 11794, USA
| | - Joseph Lachance
- Department of Biology and Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA; Department of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Sarah A Tishkoff
- Department of Biology and Genetics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Jeffrey D Wall
- Institute for Human Genetics, University of California, San Francisco, California 94143, USA
| | - Michael F Hammer
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA; Arizona Research Laboratories Division of Biotechnology, University of Arizona, Tucson, Arizona 85721, USA
| | - Ryan N Gutenkunst
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721, USA; Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, USA
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Marston S, Montgiraud C, Munster AB, Copeland O, Choi O, dos Remedios C, Messer AE, Ehler E, Knöll R. OBSCN Mutations Associated with Dilated Cardiomyopathy and Haploinsufficiency. PLoS One 2015; 10:e0138568. [PMID: 26406308 PMCID: PMC4583186 DOI: 10.1371/journal.pone.0138568] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 08/01/2015] [Indexed: 11/18/2022] Open
Abstract
Background Studies of the functional consequences of DCM-causing mutations have been limited to a few cases where patients with known mutations had heart transplants. To increase the number of potential tissue samples for direct investigation we performed whole exon sequencing of explanted heart muscle samples from 30 patients that had a diagnosis of familial dilated cardiomyopathy and screened for potentially disease-causing mutations in 58 HCM or DCM-related genes. Results We identified 5 potentially disease-causing OBSCN mutations in 4 samples; one sample had two OBSCN mutations and one mutation was judged to be not disease-related. Also identified were 6 truncating mutations in TTN, 3 mutations in MYH7, 2 in DSP and one each in TNNC1, TNNI3, MYOM1, VCL, GLA, PLB, TCAP, PKP2 and LAMA4. The mean level of obscurin mRNA was significantly greater and more variable in healthy donor samples than the DCM samples but did not correlate with OBSCN mutations. A single obscurin protein band was observed in human heart myofibrils with apparent mass 960 ± 60 kDa. The three samples with OBSCN mutations had significantly lower levels of obscurin immunoreactive material than DCM samples without OBSCN mutations (45±7, 48±3, and 72±6% of control level).Obscurin levels in DCM controls, donor heart and myectomy samples were the same. Conclusions OBSCN mutations may result in the development of a DCM phenotype via haploinsufficiency. Mutations in the obscurin gene should be considered as a significant causal factor of DCM, alone or in concert with other mutations.
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Affiliation(s)
- Steven Marston
- NHLI, Imperial College London, London, United Kingdom
- * E-mail:
| | | | | | | | - Onjee Choi
- NHLI, Imperial College London, London, United Kingdom
| | | | | | - Elisabeth Ehler
- Randall Division, King’s College London, London, United Kingdom
| | - Ralph Knöll
- NHLI, Imperial College London, London, United Kingdom
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The Phosphorylation Profile of Myosin Binding Protein-C Slow is Dynamically Regulated in Slow-Twitch Muscles in Health and Disease. Sci Rep 2015; 5:12637. [PMID: 26285797 PMCID: PMC4642540 DOI: 10.1038/srep12637] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 05/05/2015] [Indexed: 01/23/2023] Open
Abstract
Myosin Binding Protein-C slow (sMyBP-C) is expressed in skeletal muscles where it plays structural and regulatory roles. The functions of sMyBP-C are modulated through alternative splicing and phosphorylation. Herein, we examined the phosphorylation profile of sMyBP-C in mouse slow-twitch soleus muscle isolated from fatigued or non-fatigued young (2-4-months old) and old (~14-months old) wild type and mdx mice. Our findings are two-fold. First, we identified the phosphorylation events present in individual sMyBP-C variants at different states. Secondly, we quantified the relative abundance of each phosphorylation event, and of sMyBP-C phospho-species as a function of age and dystrophy, in the presence or absence of fatigue. Our results revealed both constitutive and differential phosphorylation of sMyBP-C. Moreover, we noted a 10–40% and a 25–35% reduction in the phosphorylation levels of select sites in old wild type and young or old mdx soleus muscles, respectively. On the contrary, we observed a 5–10% and a 20–25% increase in the phosphorylation levels of specific sites in young fatigued wild type and mdx soleus muscles, respectively. Overall, our studies showed that the phosphorylation pattern of sMyBP-C is differentially regulated following reversible (i.e. fatigue) and non-reversible (i.e. age and disease) (patho)physiological stressors.
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Loss of the obscurin-RhoGEF downregulates RhoA signaling and increases microtentacle formation and attachment of breast epithelial cells. Oncotarget 2015; 5:8558-68. [PMID: 25261370 PMCID: PMC4226704 DOI: 10.18632/oncotarget.2338] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Obscurins are RhoGEF-containing proteins whose downregulation has been implicated in the development and progression of breast cancer. Herein, we aim to elucidate the mechanism for increased motility of obscurin-deficient cells. We show that shRNA-mediated obscurin downregulation in MCF10A cells leads to >50% reduction in RhoA activity relative to scramble control (shCtrl), as well as decreased phosphorylation of RhoA effectors, including myosin light chain phosphatase, myosin light chain, lim kinase, and cofilin, in both attached and suspended cells. These alterations result in decreased actomyosin contractility, allowing suspended cells to escape detachment-induced apoptosis. Moreover, ~40% of shObsc-expressing cells, but only ~10% of shCtrl-expressing cells, extend microtentacles, tubulin-based projections that mediate the attachment of circulating tumor cells to endothelium. Indeed, we show that MCF10A cells expressing shObsc attach in vitro more readily than shCtrl cells, an advantage that persists following taxane exposure. Overall, our data suggest that loss of obscurins may represent a substantial selective advantage for breast epithelial cells during metastasis, and that treatment with paclitaxel may exacerbate this advantage by preferentially allowing obscurin-deficient, stem-like cells to attach to the endothelium of distant sites, a first step towards colonizing metastatic tumors.
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Benian GM, Mayans O. Titin and obscurin: giants holding hands and discovery of a new Ig domain subset. J Mol Biol 2014; 427:707-714. [PMID: 25555989 DOI: 10.1016/j.jmb.2014.12.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Guy M Benian
- Department of Pathology, Emory University, Atlanta, GA 30322, USA.
| | - Olga Mayans
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK.
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