1
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Alber S, Di Matteo P, Zdradzinski MD, Dalla Costa I, Medzihradszky KF, Kawaguchi R, Di Pizio A, Freund P, Panayotis N, Marvaldi L, Doron-Mandel E, Okladnikov N, Rishal I, Nevo R, Coppola G, Lee SJ, Sahoo PK, Burlingame AL, Twiss JL, Fainzilber M. PTBP1 regulates injury responses and sensory pathways in adult peripheral neurons. SCIENCE ADVANCES 2023; 9:eadi0286. [PMID: 37506203 PMCID: PMC10381954 DOI: 10.1126/sciadv.adi0286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 06/22/2023] [Indexed: 07/30/2023]
Abstract
Polypyrimidine tract binding protein 1 (PTBP1) is thought to be expressed only at embryonic stages in central neurons. Its down-regulation triggers neuronal differentiation in precursor and non-neuronal cells, an approach recently tested for generation of neurons de novo for amelioration of neurodegenerative disorders. Moreover, PTBP1 is replaced by its paralog PTBP2 in mature central neurons. Unexpectedly, we found that both proteins are coexpressed in adult sensory and motor neurons, with PTBP2 restricted mainly to the nucleus, while PTBP1 also shows axonal localization. Levels of axonal PTBP1 increased markedly after peripheral nerve injury, and it associates in axons with mRNAs involved in injury responses and nerve regeneration, including importin β1 (KPNB1) and RHOA. Perturbation of PTBP1 affects local translation in axons, nociceptor neuron regeneration and both thermal and mechanical sensation. Thus, PTBP1 has functional roles in adult axons. Hence, caution is required before considering targeting of PTBP1 for therapeutic purposes.
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Affiliation(s)
- Stefanie Alber
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Pierluigi Di Matteo
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Matthew D. Zdradzinski
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Irene Dalla Costa
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Katalin F. Medzihradszky
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Riki Kawaguchi
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Agostina Di Pizio
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Philip Freund
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nicolas Panayotis
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Letizia Marvaldi
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
- Department of Neuroscience “Rita Levi Montalcini”, Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Orbassano 10043, Italy
| | - Ella Doron-Mandel
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nataliya Okladnikov
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ida Rishal
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Reinat Nevo
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Giovanni Coppola
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Seung Joon Lee
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Pabitra K. Sahoo
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Alma L. Burlingame
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158, USA
| | - Jeffery L. Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Mike Fainzilber
- Departments of Biomolecular Sciences and Molecular Neuroscience, Weizmann Institute of Science, Rehovot 7610001, Israel
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2
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Fu XD, Mobley WC. Therapeutic Potential of PTB Inhibition Through Converting Glial Cells to Neurons in the Brain. Annu Rev Neurosci 2023; 46:145-165. [PMID: 37428606 DOI: 10.1146/annurev-neuro-083022-113120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/12/2023]
Abstract
Cell replacement therapy represents a promising approach for treating neurodegenerative diseases. Contrary to the common addition strategy to generate new neurons from glia by overexpressing a lineage-specific transcription factor(s), a recent study introduced a subtraction strategy by depleting a single RNA-binding protein, Ptbp1, to convert astroglia to neurons not only in vitro but also in the brain. Given its simplicity, multiple groups have attempted to validate and extend this attractive approach but have met with difficulty in lineage tracing newly induced neurons from mature astrocytes, raising the possibility of neuronal leakage as an alternative explanation for apparent astrocyte-to-neuron conversion. This review focuses on the debate over this critical issue. Importantly, multiple lines of evidence suggest that Ptbp1 depletion can convert a selective subpopulation of glial cells into neurons and, via this and other mechanisms, reverse deficits in a Parkinson's disease model, emphasizing the importance of future efforts in exploring this therapeutic strategy.
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Affiliation(s)
- Xiang-Dong Fu
- Westlake Laboratory of Life Sciences and Biomedicine, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China;
| | - William C Mobley
- Department of Neuroscience, University of California, San Diego, La Jolla, California, USA;
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3
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Stark M, Levin M, Ulitsky I, Assaraf YG. Folylpolyglutamate synthetase mRNA G-quadruplexes regulate its cell protrusion localization and enhance a cancer cell invasive phenotype upon folate repletion. BMC Biol 2023; 21:13. [PMID: 36721160 PMCID: PMC9889130 DOI: 10.1186/s12915-023-01525-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 01/23/2023] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Folates are crucial for the biosynthesis of nucleotides and amino acids, essential for cell proliferation and development. Folate deficiency induces DNA damage, developmental defects, and tumorigenicity. The obligatory enzyme folylpolyglutamate synthetase (FPGS) mediates intracellular folate retention via cytosolic and mitochondrial folate polyglutamylation. Our previous paper demonstrated the association of the cytosolic FPGS (cFPGS) with the cytoskeleton and various cell protrusion proteins. Based on these recent findings, the aim of the current study was to investigate the potential role of cFPGS at cell protrusions. RESULTS Here we uncovered a central role for two G-quadruplex (GQ) motifs in the 3'UTR of FPGS mediating the localization of cFPGS mRNA and protein at cell protrusions. Using the MBSV6-loop reporter system and fluorescence microscopy, we demonstrate that following folate deprivation, cFPGS mRNA is retained in the endoplasmic reticulum, whereas upon 15 min of folate repletion, this mRNA is rapidly translocated to cell protrusions in a 3'UTR- and actin-dependent manner. The actin dependency of this folate-induced mRNA translocation is shown by treatment with Latrunculin B and inhibitors of the Ras homolog family member A (RhoA) pathway. Upon folate repletion, the FPGS 3'UTR GQs induce an amoeboid/mesenchymal hybrid cell phenotype during migration and invasion through a collagen gel matrix. Targeted disruption of the 3'UTR GQ motifs by introducing point mutations or masking them by antisense oligonucleotides abrogated cell protrusion targeting of cFPGS mRNA. CONCLUSIONS Collectively, the GQ motifs within the 3'UTR of FPGS regulate its transcript and protein localization at cell protrusions in response to a folate cue, inducing cancer cell invasive phenotype. These novel findings suggest that the 3'UTR GQ motifs of FPGS constitute an attractive druggable target aimed at inhibition of cancer invasion and metastasis.
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Affiliation(s)
- Michal Stark
- grid.6451.60000000121102151The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, 3200003 Haifa, Israel
| | - May Levin
- grid.6451.60000000121102151The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, 3200003 Haifa, Israel ,grid.507132.2Present address: May Levin, MeMed Diagnostics Ltd, Tirat Carmel, Israel
| | - Igor Ulitsky
- grid.13992.300000 0004 0604 7563Department of Immunology and Regenerative Biology and Department of Molecular Neuroscience, Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Yehuda G. Assaraf
- grid.6451.60000000121102151The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, 3200003 Haifa, Israel
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4
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Dai S, Wang C, Zhang C, Feng L, Zhang W, Zhou X, He Y, Xia X, Chen B, Song W. PTB: Not just a polypyrimidine tract-binding protein. J Cell Physiol 2022; 237:2357-2373. [PMID: 35288937 DOI: 10.1002/jcp.30716] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/19/2022] [Accepted: 02/22/2022] [Indexed: 01/21/2023]
Abstract
Polypyrimidine tract-binding protein (PTB), as a member of the heterogeneous nuclear ribonucleoprotein family, functions by rapidly shuttling between the nucleus and the cytoplasm. PTB is involved in the alternative splicing of pre-messenger RNA (mRNA) and almost all steps of mRNA metabolism. PTB regulation is organ-specific; brain- or muscle-specific microRNAs and long noncoding RNAs partially contribute to regulating PTB, thereby modulating many physiological and pathological processes, such as embryonic development, cell development, spermatogenesis, and neuron growth and differentiation. Previous studies have shown that PTB knockout can inhibit tumorigenesis and development. The knockout of PTB in glial cells can be reprogrammed into functional neurons, which shows great promise in the field of nerve regeneration but is controversial.
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Affiliation(s)
- Shirui Dai
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China.,Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, P. R. China
| | - Chao Wang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Cheng Zhang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Lemeng Feng
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Wulong Zhang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Xuezhi Zhou
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Ye He
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Xiaobo Xia
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Baihua Chen
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, P. R. China
| | - Weitao Song
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
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5
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McCormack M, Dillon E, O’Connor I, MacCarthy E. Investigation of the Initial Host Response of Naïve Atlantic Salmon ( Salmo salar) Inoculated with Paramoeba perurans. Microorganisms 2021; 9:microorganisms9040746. [PMID: 33918228 PMCID: PMC8066739 DOI: 10.3390/microorganisms9040746] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/23/2021] [Accepted: 03/31/2021] [Indexed: 01/15/2023] Open
Abstract
Amoebic Gill Disease (AGD), caused by the ectoparasite Paramoeba perurans is characterised by hyperplasia of the gill epithelium and lamellar fusion. In this study, the initial host response of naïve Atlantic salmon (Salmo salar) inoculated with P. perurans was investigated. Using gel-free proteomic techniques and mass spectrometry gill and serum samples were analysed at 7 timepoints (2, 3, 4, 7, 9, 11 and 14 days) post-inoculation with P. perurans. Differential expression of immune related proteins was assessed by comparison of protein expression from each time point against naïve controls. Few host immune molecules associated with innate immunity showed increased expression in response to gill colonisation by amoebae. Furthermore, many proteins with roles in immune signalling, phagocytosis and T-cell proliferation were found to be inhibited upon disease progression. Initially, various immune factors demonstrated the anticipated increase in expression in response to infection in the serum while some immune inhibition became apparent at the later stages of disease progression. Taken together, the pro-immune trend observed in serum, the lack of a robust early immune response in the gill and the diversity of those proteins in the gill whose altered expression negatively impact the immune response, support the concept of a pathogen-derived suppression of the host response.
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Affiliation(s)
- Michelle McCormack
- Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Dublin Road, H91 TRNW Galway, Ireland; (I.O.); (E.M.)
- Correspondence:
| | - Eugene Dillon
- Conway Institute of Biomolecular & Biomedical Research, University College Dublin, D04 V1W8 Dublin, Ireland;
| | - Ian O’Connor
- Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Dublin Road, H91 TRNW Galway, Ireland; (I.O.); (E.M.)
| | - Eugene MacCarthy
- Marine and Freshwater Research Centre, Galway Mayo Institute of Technology, Dublin Road, H91 TRNW Galway, Ireland; (I.O.); (E.M.)
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6
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Ontiveros RJ, Hernandez L, Nguyen H, Hernandez Lopez AL, Shankar A, Kim E, Keppetipola NM. Identification and Characterization of a Minimal Functional Splicing Regulatory Protein, PTBP1. Biochemistry 2020; 59:4766-4774. [PMID: 33284593 DOI: 10.1021/acs.biochem.0c00664] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polypyrimidine tract binding protein 1 (PTBP1) is a well-studied RNA binding protein that serves as an important model for understanding molecular mechanisms underlying alternative splicing regulation. PTBP1 has four RNA binding domains (RBDs) connected via linker regions. Additionally, PTBP1 has an N-terminal unstructured region that contains nuclear import and export sequences. Each RBD can bind to pyrimidine rich elements with high affinity to mediate splicing activity. Studies support a variety of models for how PTBP1 can mediate splicing regulation on target exons. Obtaining a detailed atomic view hinges on determining a crystal structure of PTBP1 bound to a target RNA transcript. Here, we created a minimal functional PTBP1 with deletions in both linker 1 and linker 2 regions and assayed for activity on certain regulated exons, including the c-Src N1 exon. We show that for a subset of PTBP1-regulated exons the linker regions are not necessary for splicing repression activity. Gel mobility shift assays reveal the linker deletion mutant binds with 12-fold higher affinity to a target RNA sequence compared to wild-type PTBP1. A minimal PTBP1 that also contains an N-terminal region deletion binds to a target RNA with an affinity higher than that of wild-type PTBP1. Moreover, this minimal protein oligomerizes readily to form a distinct higher-order complex previously shown to be required for mediating splicing repression. This minimal functional PTBP1 protein can serve as a candidate for future structure studies to understand the mechanism of splicing repression for certain regulated exons.
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Affiliation(s)
- Robert J Ontiveros
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Luis Hernandez
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Haylena Nguyen
- Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, California 92831, United States
| | - Adrian Lino Hernandez Lopez
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, California 90035, United States
| | - Archana Shankar
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Enoch Kim
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Niroshika M Keppetipola
- Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, California 92831, United States
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7
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Simpson LJ, Tzima E, Reader JS. Mechanical Forces and Their Effect on the Ribosome and Protein Translation Machinery. Cells 2020; 9:cells9030650. [PMID: 32156009 PMCID: PMC7140433 DOI: 10.3390/cells9030650] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/03/2020] [Accepted: 03/04/2020] [Indexed: 12/12/2022] Open
Abstract
Mechanical forces acting on biological systems, at both the macroscopic and microscopic levels, play an important part in shaping cellular phenotypes. There is a growing realization that biomolecules that respond to force directly applied to them, or via mechano-sensitive signalling pathways, can produce profound changes to not only transcriptional pathways, but also in protein translation. Forces naturally occurring at the molecular level can impact the rate at which the bacterial ribosome translates messenger RNA (mRNA) transcripts and influence processes such as co-translational folding of a nascent protein as it exits the ribosome. In eukaryotes, force can also be transduced at the cellular level by the cytoskeleton, the cell’s internal filamentous network. The cytoskeleton closely associates with components of the translational machinery such as ribosomes and elongation factors and, as such, is a crucial determinant of localized protein translation. In this review we will give (1) a brief overview of protein translation in bacteria and eukaryotes and then discuss (2) how mechanical forces are directly involved with ribosomes during active protein synthesis and (3) how eukaryotic ribosomes and other protein translation machinery intimately associates with the mechanosensitive cytoskeleton network.
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8
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Chen J, Zhang J, Shaik NF, Yi B, Wei X, Yang XF, Naik UP, Summer R, Yan G, Xu X, Sun J. The histone deacetylase inhibitor tubacin mitigates endothelial dysfunction by up-regulating the expression of endothelial nitric oxide synthase. J Biol Chem 2019; 294:19565-19576. [PMID: 31719145 DOI: 10.1074/jbc.ra119.011317] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/06/2019] [Indexed: 01/03/2023] Open
Abstract
Endothelial nitric oxide (NO) synthase (eNOS) plays a critical role in the maintenance of blood vessel homeostasis. Recent findings suggest that cytoskeletal dynamics play an essential role in regulating eNOS expression and activation. Here, we sought to test whether modulation of cytoskeletal dynamics through pharmacological regulation of histone deacetylase 6 (HDAC6)-mediated tubulin deacetylation affects eNOS expression and endothelial function in vitro and in vivo We found that tubulin acetylation inducer (tubacin), a compound that appears to selectively inhibit HDAC6 activity, dramatically increased eNOS expression in several different endothelial cell lines, as determined by both immunoblotting and NO production assays. Mechanistically, we found that these effects were not mediated by tubacin's inhibitory effect on HDAC6 activity, but rather were due to its ability to stabilize eNOS mRNA transcripts. Consistent with these findings, tubacin also inhibited proinflammatory cytokine-induced degradation of eNOS transcripts and impairment of endothelium-dependent relaxation in the mouse aorta. Furthermore, we found that tubacin-induced up-regulation in eNOS expression in vivo is associated with improved endothelial function in diabetic db/db mice and with a marked attenuation of ischemic brain injury in a murine stroke model. Our findings indicate that tubacin exhibits potent eNOS-inducing effects and suggest that this compound might be useful for the prevention or management of endothelial dysfunction-associated cardiovascular diseases.
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Affiliation(s)
- Jihui Chen
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.,Department of Pharmacy, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200092, China
| | - Jian Zhang
- Department of Pharmacy, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200092, China
| | - Noor F Shaik
- Cardeza Center for Vascular Biology, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Bing Yi
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Xin Wei
- Department of Pharmacy, Xinhua Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200092, China
| | - Xiao-Feng Yang
- Center for Metabolic Disease Research, Lewis Katz School of Medicine at Temple University, Philadelphia, Pennsylvania 19107
| | - Ulhas P Naik
- Cardeza Center for Vascular Biology, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Ross Summer
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Guijun Yan
- Reproductive Medicine Center, Affiliated Drum Tower Hospital of Nanjing University Medical School, Nanjing 210023, China
| | - Xinyun Xu
- Department of General Surgery, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai 200003, China
| | - Jianxin Sun
- Center for Translational Medicine, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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9
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The 3′UTR of the α6 integrin message regulates localization of α6β4 integrin heterodimers. Biochem Biophys Res Commun 2019; 513:8-14. [DOI: 10.1016/j.bbrc.2019.03.116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 03/18/2019] [Indexed: 11/19/2022]
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10
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Shen K, Kenche H, Zhao H, Li J, Stone J. The role of extracellular matrix stiffness in regulating cytoskeletal remodeling via vinculin in synthetic smooth muscle cells. Biochem Biophys Res Commun 2018; 508:302-307. [PMID: 30502091 DOI: 10.1016/j.bbrc.2018.11.142] [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: 11/11/2018] [Accepted: 11/21/2018] [Indexed: 01/01/2023]
Abstract
Vinculin is a key player in sensing and responding to external mechanical cues such as extracellular matrix stiffness. Increased matrix stiffness is often associated with certain pathological conditions including hypertension induced cellular cytoskeleton changes in vascular smooth muscle (VSM) cells. However, little is known on how stiffness affects cytoskeletal remodeling via vinculin in VSM cells. Thus, we utilized matrices with elastic moduli that simulate vascular stiffness in different stages of hypertension to investigate how matrix stiffness regulates cell cytoskeleton via vinculin in synthetic VSM cells. Through selecting a suitable reference gene, we found that an increase in physiologically relevant extracellular matrix stiffness (2-50 kPa) downregulates vinculin gene expression but upregulates vinculin protein expression. This discrepancy, which was not observed previously for non-muscle cells, suggests that the vinculin-mediated mecahnotransduction mechanism in synthetic VSM cells may be more complex than those proposed for non-muscle cells. Also adding to previous findings, we found that VSM cell growth may be impeded by substrates that are either too soft or too rigid.
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Affiliation(s)
- Kai Shen
- Department of Chemistry and Forensic Science, Savannah State University, Savannah, GA, 31404, USA.
| | - Harshavardhan Kenche
- Department of Chemistry and Forensic Science, Savannah State University, Savannah, GA, 31404, USA
| | - Hua Zhao
- Department of Chemistry and Biochemistry, University of Northern Colorado, Greeley, CO, 80639, USA
| | - Jinping Li
- Department of Biomedical Science, Mercer University School of Medicine, Savannah, GA, 31404, USA
| | - Jasimine Stone
- Department of Chemistry and Forensic Science, Savannah State University, Savannah, GA, 31404, USA
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11
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Bansal D, Kulkarni J, Nadahalli K, Lakshmanan V, Krishna S, Sasidharan V, Geo J, Dilipkumar S, Pasricha R, Gulyani A, Raghavan S, Palakodeti D. Cytoplasmic poly (A)-binding protein critically regulates epidermal maintenance and turnover in the planarian Schmidtea mediterranea. Development 2017; 144:3066-3079. [PMID: 28807897 PMCID: PMC5611960 DOI: 10.1242/dev.152942] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/21/2017] [Indexed: 12/17/2022]
Abstract
Identifying key cellular events that facilitate stem cell function and tissue organization is crucial for understanding the process of regeneration. Planarians are powerful model system to study regeneration and stem cell (neoblast) function. Here, using planaria, we show that the initial events of regeneration, such as epithelialization and epidermal organization are critically regulated by a novel cytoplasmic poly A-binding protein, SMED-PABPC2. Knockdown of smed-pabpc2 leads to defects in epidermal lineage specification, disorganization of epidermis and ECM, and deregulated wound healing, resulting in the selective failure of neoblast proliferation near the wound region. Polysome profiling suggests that epidermal lineage transcripts, including zfp-1, are translationally regulated by SMED-PABPC2. Together, our results uncover a novel role for SMED-PABPC2 in the maintenance of epidermal and ECM integrity, critical for wound healing and subsequent processes for regeneration.
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Affiliation(s)
- Dhiru Bansal
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
- Manipal University, Manipal 576104, India
| | - Jahnavi Kulkarni
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
| | - Kavana Nadahalli
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
- Transdisciplinary University, Bangalore 560064, India
| | - Vairavan Lakshmanan
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
- Sastra University, Thanjavur 613402 India
| | - Srikar Krishna
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
- Sastra University, Thanjavur 613402 India
| | - Vidyanand Sasidharan
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
- Manipal University, Manipal 576104, India
| | - Jini Geo
- National Centre for Biological Sciences, GKVK PO, Bellary Road, Bangalore 560065, India
| | - Shilpa Dilipkumar
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
| | - Renu Pasricha
- National Centre for Biological Sciences, GKVK PO, Bellary Road, Bangalore 560065, India
| | - Akash Gulyani
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
| | - Srikala Raghavan
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
| | - Dasaradhi Palakodeti
- Institute for Stem Cell Biology and Regenerative Medicine, GKVK PO, Bellary Road, Bangalore 560065, India
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12
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Danan-Gotthold M, Golan-Gerstl R, Eisenberg E, Meir K, Karni R, Levanon EY. Identification of recurrent regulated alternative splicing events across human solid tumors. Nucleic Acids Res 2015; 43:5130-44. [PMID: 25908786 PMCID: PMC4446417 DOI: 10.1093/nar/gkv210] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2014] [Accepted: 03/02/2015] [Indexed: 12/21/2022] Open
Abstract
Cancer is a complex disease that involves aberrant gene expression regulation. Discriminating the modified expression patterns driving tumor biology from the many that have no or little contribution is important for understanding cancer molecular basis. Recurrent deregulation patterns observed in multiple cancer types are enriched for such driver events. Here, we studied splicing alterations in hundreds of matched tumor and normal RNA-seq samples of eight solid cancer types. We found hundreds of cassette exons for which splicing was altered in multiple cancer types and identified a set of highly frequent altered splicing events. Specific splicing regulators, including RBFOX2, MBNL1/2 and QKI, appear to account for many splicing alteration events in multiple cancer types. Together, our results provide a first global analysis of regulated splicing alterations in cancer and identify common events with a potential causative role in solid tumor development.
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Affiliation(s)
- Miri Danan-Gotthold
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
| | - Regina Golan-Gerstl
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Ein Karem, 91120 Jerusalem, Israel
| | - Eli Eisenberg
- Raymond and Beverly Sackler School of Physics and Astronomy and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
| | - Keren Meir
- Department of Pathology, Hadassah Medical Center, Hebrew University, Jerusalem, Israel
| | - Rotem Karni
- Department of Biochemistry and Molecular Biology, the Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Ein Karem, 91120 Jerusalem, Israel
| | - Erez Y Levanon
- Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel
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13
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Simpson CG, Lewandowska D, Liney M, Davidson D, Chapman S, Fuller J, McNicol J, Shaw P, Brown JWS. Arabidopsis PTB1 and PTB2 proteins negatively regulate splicing of a mini-exon splicing reporter and affect alternative splicing of endogenous genes differentially. THE NEW PHYTOLOGIST 2014; 203:424-436. [PMID: 24749484 DOI: 10.1111/nph.12821] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 03/14/2013] [Indexed: 06/03/2023]
Abstract
This paper examines the function of Arabidopsis thaliana AtPTB1 and AtPTB2 as plant splicing factors. The effect on splicing of overexpression of AtPTB1 and AtPTB2 was analysed in an in vivo protoplast transient expression system with a novel mini-exon splicing reporter. A range of mutations in pyrimidine-rich sequences were compared with and without AtPTB and NpU2AF65 overexpression. Splicing analyses of constructs in protoplasts and RNA from overexpression lines used high-resolution reverse transcription polymerase chain reaction (RT-PCR). AtPTB1 and AtPTB2 reduced inclusion/splicing of the potato invertase mini-exon splicing reporter, indicating that these proteins can repress plant intron splicing. Mutation of the polypyrimidine tract and closely associated Cytosine and Uracil-rich (CU-rich) sequences, upstream of the mini-exon, altered repression by AtPTB1 and AtPTB2. Coexpression of a plant orthologue of U2AF65 alleviated the splicing repression of AtPTB1. Mutation of a second CU-rich upstream of the mini-exon 3' splice site led to a decline in mini-exon splicing, indicating the presence of a splicing enhancer sequence. Finally, RT-PCR of AtPTB overexpression lines with c. 90 known alternative splicing (AS) events showed that AtPTBs significantly altered AS of over half the events. AtPTB1 and AtPTB2 are splicing factors that influence alternative splicing. This occurs in the potato invertase mini-exon via the polypyrimidine tract and associated pyrimidine-rich sequence.
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Affiliation(s)
- Craig G Simpson
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Dominika Lewandowska
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Michele Liney
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Diane Davidson
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Sean Chapman
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - John Fuller
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - Jim McNicol
- Biomathematics and Statistics Scotland, Invergowrie, Dundee, DD2 5DA, UK
| | - Paul Shaw
- Information and Computational Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - John W S Brown
- Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
- Division of Plant Sciences, University of Dundee at JHI, Invergowrie, Dundee, DD2 5DA, UK
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14
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New insights into functional roles of the polypyrimidine tract-binding protein. Int J Mol Sci 2013; 14:22906-32. [PMID: 24264039 PMCID: PMC3856098 DOI: 10.3390/ijms141122906] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Revised: 11/13/2013] [Accepted: 11/13/2013] [Indexed: 12/20/2022] Open
Abstract
Polypyrimidine Tract Binding Protein (PTB) is an intensely studied RNA binding protein involved in several post-transcriptional regulatory events of gene expression. Initially described as a pre-mRNA splicing regulator, PTB is now widely accepted as a multifunctional protein shuttling between nucleus and cytoplasm. Accordingly, PTB can interact with selected RNA targets, structural elements and proteins. There is increasing evidence that PTB and its paralog PTBP2 play a major role as repressors of alternatively spliced exons, whose transcription is tissue-regulated. In addition to alternative splicing, PTB is involved in almost all steps of mRNA metabolism, including polyadenylation, mRNA stability and initiation of protein translation. Furthermore, it is well established that PTB recruitment in internal ribosome entry site (IRES) activates the translation of picornaviral and cellular proteins. Detailed studies of the structural properties of PTB have contributed to our understanding of the mechanism of RNA binding by RNA Recognition Motif (RRM) domains. In the present review, we will describe the structural properties of PTB, its paralogs and co-factors, the role in post-transcriptional regulation and actions in cell differentiation and pathogenesis. Defining the multifunctional roles of PTB will contribute to the understanding of key regulatory events in gene expression.
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15
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McDermott SM, Davis I. Drosophila Hephaestus/polypyrimidine tract binding protein is required for dorso-ventral patterning and regulation of signalling between the germline and soma. PLoS One 2013; 8:e69978. [PMID: 23894566 PMCID: PMC3720928 DOI: 10.1371/journal.pone.0069978] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 06/14/2013] [Indexed: 02/05/2023] Open
Abstract
In the Drosophila oocyte, gurken (grk) mRNA encodes a secreted TGF-α signal that specifies the future embryonic dorso-ventral axes by altering the fate of the surrounding epithelial follicle cells. We previously identified a number of RNA binding proteins that associate specifically with the 64 nucleotide grk localization signal, including the Drosophila orthologue of polypyrimidine tract-binding protein (PTB), Hephaestus (Heph). To test whether Heph is required for correct grk mRNA or protein function, we used immunoprecipitation to validate the association of Heph with grk mRNA and characterized the heph mutant phenotype. We found that Heph is a component of grk mRNP complexes but heph germline clones show that Heph is not required for grk mRNA localization. Instead, we identify a novel function for Heph in the germline and show that it is required for proper Grk protein localization. Furthermore, we show that Heph is required in the oocyte for the correct organization of the actin cytoskeleton and dorsal appendage morphogenesis. Our results highlight a requirement for an mRNA binding protein in the localization of Grk protein, which is independent of mRNA localization, and we propose that Heph is required in the germline for efficient Grk signalling to the somatic follicle cells during dorso-ventral patterning.
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Affiliation(s)
- Suzanne M. McDermott
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (SMM); (ID)
| | - Ilan Davis
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail: (SMM); (ID)
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16
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Deshpande P, Ramachandran C, Sefat F, Mariappan I, Johnson C, McKean R, Hannah M, Sangwan VS, Claeyssens F, Ryan AJ, MacNeil S. Simplifying corneal surface regeneration using a biodegradable synthetic membrane and limbal tissue explants. Biomaterials 2013; 34:5088-106. [DOI: 10.1016/j.biomaterials.2013.03.064] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Accepted: 03/25/2013] [Indexed: 10/27/2022]
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17
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Katz ZB, Wells AL, Park HY, Wu B, Shenoy SM, Singer RH. β-Actin mRNA compartmentalization enhances focal adhesion stability and directs cell migration. Genes Dev 2012; 26:1885-90. [PMID: 22948660 DOI: 10.1101/gad.190413.112] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Directed cell motility is at the basis of biological phenomena such as development, wound healing, and metastasis. It has been shown that substrate attachments mediate motility by coupling the cell's cytoskeleton with force generation. However, it has been unclear how the persistence of cell directionality is facilitated. We show that mRNA localization plays an important role in this process, but the mechanism of action is still unknown. In this study, we show that the zipcode-binding protein 1 transports β-actin mRNA to the focal adhesion compartment, where it dwells for minutes, suggesting a means for associating its localization with motility through the formation of stable connections between adhesions and newly synthesized actin filaments. In order to demonstrate this, we developed an approach for assessing the functional consequences of β-actin mRNA and protein localization by tethering the mRNA to a specific location-in this case, the focal adhesion complex. This approach will have a significant impact on cell biology because it is now possible to forcibly direct any mRNA and its cognate protein to specific locations in the cell. This will reveal the importance of localized protein translation on various cellular processes.
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Affiliation(s)
- Zachary B Katz
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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18
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Shibasaki T, Tokunaga A, Sakamoto R, Sagara H, Noguchi S, Sasaoka T, Yoshida N. PTB Deficiency Causes the Loss of Adherens Junctions in the Dorsal Telencephalon and Leads to Lethal Hydrocephalus. Cereb Cortex 2012; 23:1824-35. [DOI: 10.1093/cercor/bhs161] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
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19
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Keppetipola N, Sharma S, Li Q, Black DL. Neuronal regulation of pre-mRNA splicing by polypyrimidine tract binding proteins, PTBP1 and PTBP2. Crit Rev Biochem Mol Biol 2012; 47:360-78. [PMID: 22655688 DOI: 10.3109/10409238.2012.691456] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Alternative splicing patterns are regulated by RNA binding proteins that assemble onto each pre-mRNA to form a complex RNP structure. The polypyrimidine tract binding protein, PTB, has served as an informative model for understanding how RNA binding proteins affect spliceosome assembly and how changes in the expression of these proteins can control complex programs of splicing in tissues. In this review, we describe the mechanisms of splicing regulation by PTB and its function, along with its paralog PTBP2, in neuronal development.
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Affiliation(s)
- Niroshika Keppetipola
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA
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20
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David CJ, Manley JL. Alternative pre-mRNA splicing regulation in cancer: pathways and programs unhinged. Genes Dev 2011; 24:2343-64. [PMID: 21041405 DOI: 10.1101/gad.1973010] [Citation(s) in RCA: 621] [Impact Index Per Article: 47.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Alternative splicing of mRNA precursors is a nearly ubiquitous and extremely flexible point of gene control in humans. It provides cells with the opportunity to create protein isoforms of differing, even opposing, functions from a single gene. Cancer cells often take advantage of this flexibility to produce proteins that promote growth and survival. Many of the isoforms produced in this manner are developmentally regulated and are preferentially re-expressed in tumors. Emerging insights into this process indicate that pathways that are frequently deregulated in cancer often play important roles in promoting aberrant splicing, which in turn contributes to all aspects of tumor biology.
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Affiliation(s)
- Charles J David
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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21
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New insights into vinculin function and regulation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2011; 287:191-231. [PMID: 21414589 DOI: 10.1016/b978-0-12-386043-9.00005-0] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Vinculin is a cytoplasmic actin-binding protein enriched in focal adhesions and adherens junctions that is essential for embryonic development. Much is now known regarding the role of vinculin in governing cell-matrix adhesion. In the past decade that the crystal structure of vinculin and the molecular details for how vinculin regulates adhesion events have emerged. The recent data suggests a critical function for vinculin in regulating integrin clustering, force generation, and strength of adhesion. In addition to an important role in cell-matrix adhesion, vinculin is also emerging as a regulator of apoptosis, Shigella entry into host cells, and cadherin-based cell-cell adhesion. A close inspection of this work reveals that there are similarities between vinculin's role in focal adhesions and these processes and also some intriguing differences.
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22
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Bitel CL, Perrone-Bizzozero NI, Frederikse PH. HuB/C/D, nPTB, REST4, and miR-124 regulators of neuronal cell identity are also utilized in the lens. Mol Vis 2010; 16:2301-16. [PMID: 21139978 PMCID: PMC2994760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2010] [Accepted: 10/25/2010] [Indexed: 12/04/2022] Open
Abstract
PURPOSE An interlocking network of transcription factors, RNA binding proteins, and miRNAs globally regulates gene expression and alternative splicing throughout development, and ensures the coordinated mutually exclusive expression of non-neural and neuronal forms of these factors during neurogenesis. Striking similarities between lens fiber cell and neuron cell morphology led us to determine if these factors are also used in the lens. HuR and polypyrimidine tract binding protein (PTB) have been described as 'global regulators' of RNA alternative splicing, stability, and translation in non-neuronal (including ectodermal) tissues examined to date in diverse species, and REST/NRSF (RE-1 Silencing Transcription Factor/Neuron Restrictive Silencing Factor) represses>2,000 neuronal genes in all non-neuronal tissues examined to date, but has not included the lens. During neurogenesis these factors are replaced by what has been considered neuron-specific HuB/C/D, nPTB, and alternatively spliced REST (REST4), which work with miR-124 to activate this battery of genes, comprehensively reprogram neuronal alternative splicing, and maintain their exclusive expression in post-mitotic neurons. METHODS Immunoprecipitation, western blot, immunofluorescence, and immunohistochemistry were used to determine the expression and distribution of proteins in mouse and rat lenses. Mobility shift assays were used to examine lenses for REST/NRSF DNA binding activity, and RT-PCR, DNA sequencing, and northern blots were used to identify RNA expression and alternative splicing events in lenses from mouse, rat, and goldfish (N. crassa). RESULTS We demonstrated that REST, HuR, and PTB proteins are expressed predominantly in epithelial cells in mouse and rat lenses, and showed these factors are also replaced by the predominant expression of REST4, HuB/C/D and nPTB in post-mitotic fiber cells, together with miR-124 expression in vertebrate lenses. REST-regulated gene products were found to be restricted to fiber cells where REST is decreased. These findings predicted nPTB- and HuB/C/D-dependent splicing reactions can also occur in lenses, and we showed Neuronal C-src and Type 1 Neurofibromatosis 1 splicing as well as calcitonin gene related peptide (CGRP) and neural cell adhesion molecule (NCAM-180) alternative transcripts in lenses. Transgenic mice with increased HuD in lens also showed increased growth associated protein 43 (GAP43) and Ca++/Calmodulin dependent kinase IIα (CamKIIα) HuD target gene expression in the lens, similar to brain. CONCLUSIONS The present study provides the first evidence this fundamental set of regulatory factors, previously considered to have a unique role in governing neurogenesis are also used in the lens, and raises questions about the origins of these developmental factors and mechanisms in lens and neuronal cells that also have a basic role in determining the neuronal phenotype.
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Affiliation(s)
- Claudine L. Bitel
- Department of Pharmacology and Physiology & Rutgers-UMDNJ Integrative Neurosciences Program, UMDNJ New Jersey Medical School, Newark, NJ
| | | | - Peter H. Frederikse
- Department of Pharmacology and Physiology & Rutgers-UMDNJ Integrative Neurosciences Program, UMDNJ New Jersey Medical School, Newark, NJ
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23
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Drosophila polypyrimidine tract-binding protein is necessary for spermatid individualization. Proc Natl Acad Sci U S A 2010; 107:12570-5. [PMID: 20616016 DOI: 10.1073/pnas.1007935107] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Although mammalian polypyrimidine tract-binding (PTB) protein functions in most or all cell types to regulate a wide spectrum of transcripts, Drosophila PTB encodes an abundant male germline-specific mRNA isoform (dmPTB) whose expression correlates with male fertility. The biological function of this isoform is unknown. Using selection-amplification, we show that mammalian and Drosophila PTB have similar RNA sequence preference, suggesting that cell-specific expression rather than unique RNA-binding properties account for the sex-specific function of dmPTB. We also show that the dmPTB protein isoform expressed in the male germline is by far the most abundant isoform, and reduction of its levels correlates with male sterility. Finally, we show that dmPTB expression is necessary for proper spermatid individualization, the terminal step necessary for production of motile sperm. Loss of dmPTB results in severe disruption of the actin cones of the spermatid individualization complex. This represents a cytological defect resulting from PTB loss. We discuss the basis for functional differences between mammalian and Drosophila PTB orthologs.
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Localization of ribosomes and translation initiation factors to talin/beta3-integrin-enriched adhesion complexes in spreading and migrating mammalian cells. Biol Cell 2010; 102:265-76. [PMID: 19929852 DOI: 10.1042/bc20090141] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND INFORMATION The spatial localization of translation can facilitate the enrichment of proteins at their sites of function while also ensuring that proteins are expressed in the proximity of their cognate binding partners. RESULTS Using human embryonic lung fibroblasts and employing confocal imaging and biochemical fractionation techniques, we show that ribosomes, translation initiation factors and specific RNA-binding proteins localize to nascent focal complexes along the distal edge of migrating lamellipodia. 40S ribosomal subunits appear to associate preferentially with beta3 integrin in focal adhesions at the leading edges of spreading cells, with this association strongly augmented by a synergistic effect of cell engagement with a mixture of extracellular matrix proteins. However, both ribosome and initiation factor localizations do not require de novo protein synthesis. CONCLUSIONS Taken together, these findings demonstrate that repression, complex post-transcriptional regulation and modulation of mRNA stability could potentially be taking place along the distal edge of migrating lamellipodia.
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