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Maltseva D, Tonevitsky A. RNA-binding proteins regulating the CD44 alternative splicing. Front Mol Biosci 2023; 10:1326148. [PMID: 38106992 PMCID: PMC10722200 DOI: 10.3389/fmolb.2023.1326148] [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: 10/22/2023] [Accepted: 11/15/2023] [Indexed: 12/19/2023] Open
Abstract
Alternative splicing is often deregulated in cancer, and cancer-specific isoform switches are part of the oncogenic transformation of cells. Accumulating evidence indicates that isoforms of the multifunctional cell-surface glycoprotein CD44 play different roles in cancer cells as compared to normal cells. In particular, the shift of CD44 isoforms is required for epithelial to mesenchymal transition (EMT) and is crucial for the maintenance of pluripotency in normal human cells and the acquisition of cancer stem cells phenotype for malignant cells. The growing and seemingly promising use of splicing inhibitors for treating cancer and other pathologies gives hope for the prospect of using such an approach to regulate CD44 alternative splicing. This review integrates current knowledge about regulating CD44 alternative splicing by RNA-binding proteins.
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Affiliation(s)
- Diana Maltseva
- Faculty of Biology and Biotechnology, HSE University, Moscow, Russia
| | - Alexander Tonevitsky
- Faculty of Biology and Biotechnology, HSE University, Moscow, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
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2
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Rekad Z, Ruff M, Radwanska A, Grall D, Ciais D, Van Obberghen-Schilling E. Coalescent RNA-localizing and transcriptional activities of SAM68 modulate adhesion and subendothelial basement membrane assembly. eLife 2023; 12:e85165. [PMID: 37585334 PMCID: PMC10431919 DOI: 10.7554/elife.85165] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Accepted: 07/25/2023] [Indexed: 08/18/2023] Open
Abstract
Endothelial cell interactions with their extracellular matrix are essential for vascular homeostasis and expansion. Large-scale proteomic analyses aimed at identifying components of integrin adhesion complexes have revealed the presence of several RNA binding proteins (RBPs) of which the functions at these sites remain poorly understood. Here, we explored the role of the RBP SAM68 (Src associated in mitosis, of 68 kDa) in endothelial cells. We found that SAM68 is transiently localized at the edge of spreading cells where it participates in membrane protrusive activity and the conversion of nascent adhesions to mechanically loaded focal adhesions by modulation of integrin signaling and local delivery of β-actin mRNA. Furthermore, SAM68 depletion impacts cell-matrix interactions and motility through induction of key matrix genes involved in vascular matrix assembly. In a 3D environment SAM68-dependent functions in both tip and stalk cells contribute to the process of sprouting angiogenesis. Altogether, our results identify the RBP SAM68 as a novel actor in the dynamic regulation of blood vessel networks.
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Affiliation(s)
- Zeinab Rekad
- Université Côte d'Azur, CNRS, INSERM, iBVNiceFrance
| | - Michaël Ruff
- Université Côte d'Azur, CNRS, INSERM, iBVNiceFrance
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3
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Malki I, Liepina I, Kogelnik N, Watmuff H, Robinson S, Lightfoot A, Gonchar O, Bottrill A, Fry AM, Dominguez C. Cdk1-mediated threonine phosphorylation of Sam68 modulates its RNA binding, alternative splicing activity and cellular functions. Nucleic Acids Res 2022; 50:13045-13062. [PMID: 36537190 PMCID: PMC9825155 DOI: 10.1093/nar/gkac1181] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 11/17/2022] [Accepted: 11/28/2022] [Indexed: 12/24/2022] Open
Abstract
Sam68, also known as KHDRBS1, is a member of the STAR family of proteins that directly link signal transduction with post-transcriptional gene regulation. Sam68 controls the alternative splicing of many oncogenic proteins and its role is modulated by post-translational modifications, including serine/threonine phosphorylation, that differ at various stages of the cell cycle. However, the molecular basis and mechanisms of these modulations remain largely unknown. Here, we combined mass spectrometry, nuclear magnetic resonance spectroscopy and cell biology techniques to provide a comprehensive post-translational modification mapping of Sam68 at different stages of the cell cycle in HEK293 and HCT116 cells. We established that Sam68 is specifically phosphorylated at T33 and T317 by Cdk1, and demonstrated that these phosphorylation events reduce the binding of Sam68 to RNA, control its cellular localization and reduce its alternative splicing activity, leading to a reduction in the induction of apoptosis and an increase in the proliferation of HCT116 cells.
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Affiliation(s)
- Idir Malki
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Inara Liepina
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Nora Kogelnik
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Hollie Watmuff
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Sue Robinson
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Adam Lightfoot
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Oksana Gonchar
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Andrew Bottrill
- Proteomics RTP, School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Andrew M Fry
- Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Cyril Dominguez
- The Leicester Institute of Structural and Chemical Biology and Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
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4
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Chan JNM, Sánchez-Vidaña DI, Anoopkumar-Dukie S, Li Y, Benson Wui-Man L. RNA-binding protein signaling in adult neurogenesis. Front Cell Dev Biol 2022; 10:982549. [PMID: 36187492 PMCID: PMC9523427 DOI: 10.3389/fcell.2022.982549] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 09/01/2022] [Indexed: 11/13/2022] Open
Abstract
The process of neurogenesis in the brain, including cell proliferation, differentiation, survival, and maturation, results in the formation of new functional neurons. During embryonic development, neurogenesis is crucial to produce neurons to establish the nervous system, but the process persists in certain brain regions during adulthood. In adult neurogenesis, the production of new neurons in the hippocampus is accomplished via the division of neural stem cells. Neurogenesis is regulated by multiple factors, including gene expression at a temporal scale and post-transcriptional modifications. RNA-binding Proteins (RBPs) are known as proteins that bind to either double- or single-stranded RNA in cells and form ribonucleoprotein complexes. The involvement of RBPs in neurogenesis is crucial for modulating gene expression changes and posttranscriptional processes. Since neurogenesis affects learning and memory, RBPs are closely associated with cognitive functions and emotions. However, the pathways of each RBP in adult neurogenesis remain elusive and not clear. In this review, we specifically summarize the involvement of several RBPs in adult neurogenesis, including CPEB3, FXR2, FMRP, HuR, HuD, Lin28, Msi1, Sam68, Stau1, Smaug2, and SOX2. To understand the role of these RBPs in neurogenesis, including cell proliferation, differentiation, survival, and maturation as well as posttranscriptional gene expression, we discussed the protein family, structure, expression, functional domain, and region of action. Therefore, this narrative review aims to provide a comprehensive overview of the RBPs, their function, and their role in the process of adult neurogenesis as well as to identify possible research directions on RBPs and neurogenesis.
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Affiliation(s)
- Jackie Ngai-Man Chan
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
| | - Dalinda Isabel Sánchez-Vidaña
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
- Mental Health Research Centre, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
| | | | - Yue Li
- State Key Laboratory of Component-Based Chinese Medicine, Institute of Traditional Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Lau Benson Wui-Man
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
- Mental Health Research Centre, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
- *Correspondence: Lau Benson Wui-Man,
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5
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Roles of Splicing Factors in Hormone-Related Cancer Progression. Int J Mol Sci 2020; 21:ijms21051551. [PMID: 32106418 PMCID: PMC7084890 DOI: 10.3390/ijms21051551] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 02/20/2020] [Indexed: 12/19/2022] Open
Abstract
Splicing of mRNA precursor (pre-mRNA) is a mechanism to generate multiple mRNA isoforms from a single pre-mRNA, and it plays an essential role in a variety of biological phenomena and diseases such as cancers. Previous studies have demonstrated that cancer-specific splicing events are involved in various aspects of cancers such as proliferation, migration and response to hormones, suggesting that splicing-targeting therapy can be promising as a new strategy for cancer treatment. In this review, we focus on the splicing regulation by RNA-binding proteins including Drosophila behavior/human splicing (DBHS) family proteins, serine/arginine-rich (SR) proteins and heterogeneous nuclear ribonucleoproteins (hnRNPs) in hormone-related cancers, such as breast and prostate cancers.
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6
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Splicing regulatory factors in breast cancer hallmarks and disease progression. Oncotarget 2019; 10:6021-6037. [PMID: 31666932 PMCID: PMC6800274 DOI: 10.18632/oncotarget.27215] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 08/29/2019] [Indexed: 12/31/2022] Open
Abstract
By regulating transcript isoform expression levels, alternative splicing provides an additional layer of protein control. Recent studies show evidence that cancer cells use different splicing events to fulfill their requirements in order to develop, progress and metastasize. However, there has been less attention for the role of the complex catalyzing the complicated multistep splicing reaction: the spliceosome. The spliceosome consists of multiple sub-complexes in total comprising 244 proteins or splice factors and 5 associated RNA molecules. Here we discuss the role of splice factors in the oncogenic processes tumors cells need to fulfill their oncogenic properties (the so-called the hallmarks of cancer). Despite the fact that splice factors have been investigated only recently, they seem to play a prominent role in already five hallmarks of cancer: angiogenesis, resisting cell death, sustaining proliferation, deregulating cellular energetics and invasion and metastasis formation by affecting major signaling pathways such as epithelial-to-mesenchymal transition, the Warburg effect, DNA damage response and hormone receptor dependent proliferation. Moreover, we could relate expression of representative genes of four other hallmarks (enabling replicative mortality, genomic instability, avoiding immune destruction and evading growth suppression) to splice factor levels in human breast cancer tumors, suggesting that also these hallmarks could be regulated by splice factors. Since many splice factors are involved in multiple hallmarks of cancer, inhibiting splice factors might provide a new layer of oncogenic control and a powerful method to combat breast cancer progression.
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Sawyer IA, Sturgill D, Dundr M. Membraneless nuclear organelles and the search for phases within phases. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 10:e1514. [DOI: 10.1002/wrna.1514] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/20/2018] [Accepted: 09/27/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Iain A. Sawyer
- Department of Cell Biology and Anatomy, Chicago Medical School Rosalind Franklin University of Medicine and Science North Chicago Illinois
- Laboratory of Receptor Biology and Gene Expression National Cancer Institute, National Institutes of Health Bethesda Maryland
| | - David Sturgill
- Laboratory of Receptor Biology and Gene Expression National Cancer Institute, National Institutes of Health Bethesda Maryland
| | - Miroslav Dundr
- Department of Cell Biology and Anatomy, Chicago Medical School Rosalind Franklin University of Medicine and Science North Chicago Illinois
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Chen X, Guo D, Zhu Y, Xian F, Liu S, Wu L, Lou X. Nuclear phosphoproteomics analysis reveals that CDK1/2 are involved in EGF-regulated constitutive pre-mRNA splicing in MDA-MB-468 cells. J Proteomics 2016; 141:77-84. [PMID: 27109354 DOI: 10.1016/j.jprot.2016.04.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 04/06/2016] [Accepted: 04/19/2016] [Indexed: 12/12/2022]
Abstract
UNLABELLED The epidermal growth factor (EGF) receptor (EGFR) pathway is one of the most dysregulated and extensively investigated signaling pathways in human cancers and plays important roles in the regulation of nuclear functions through both cytoplasmic and nuclear EGFR pathways. However, the current understanding of the nuclear phosphorylation responses to activated EGFR pathways remains limited. In the present study, phosphoproteomics analysis revealed the increased phosphorylation of 90 nuclear proteins, primarily involved in RNA processing, pre-mRNA splicing and cell cycle regulation, upon EGF stimulation in MDA-MB-468 cells. Cellular splicing assays of the β-globin (HBB) minigene confirmed that EGF induced constitutive pre-mRNA splicing. Further analysis of phosphoproteomics data identified multiple CDK1/2 substrates in pre-mRNA splicing-related proteins, and both CDK1/2 inhibitors and CDK1/2 knockdowns reduced EGF-regulated pre-mRNA splicing. In conclusion, the results of the present study provide evidence that CDK1/2 participate in the regulation of constitutive pre-mRNA splicing by EGF stimulation in MDA-MB-468 cells. SIGNIFICANCE In this study, we successfully carried out a survey of nuclear phosphorylation changes in response to EGF stimulation. The results from the functional category analysis and pre-mRNA splicing assay strongly indicated that EGFR activation increased constitutive pre-mRNA splicing in MDA-MB-468 cells, revealing additional role of EGFR on regulation of mRNA maturation beyond alternative pre-mRNA splicing reported by previous studies. Furthermore, we found that CDK1/2 participated in constitutive pre-mRNA splicing regulation by EGF in MDA-MB-468 cells. Our study provides new knowledge for understanding the regulation of constitutive pre-mRNA splicing by EGF stimulation.
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Affiliation(s)
- Xianwei Chen
- CAS Key Laboratory of Genome Sciences and Information, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Dan Guo
- CAS Key Laboratory of Genome Sciences and Information, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Yinghui Zhu
- CAS Key Laboratory of Genome Sciences and Information, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Feng Xian
- CAS Key Laboratory of Genome Sciences and Information, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Siqi Liu
- CAS Key Laboratory of Genome Sciences and Information, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Lin Wu
- CAS Key Laboratory of Genome Sciences and Information, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Xiaomin Lou
- CAS Key Laboratory of Genome Sciences and Information, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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9
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Bergeman J, Caillier A, Houle F, Gagné LM, Huot MÉ. Localized translation regulates cell adhesion and transendothelial migration. J Cell Sci 2016; 129:4105-4117. [DOI: 10.1242/jcs.191320] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 09/08/2016] [Indexed: 12/31/2022] Open
Abstract
By progressing through the epithelial to mesenchymal transition (EMT), cancer cells gain the ability to leave the primary tumor site and invade surrounding tissues. These metastatic cancers cells can further increase their plasticity by adopting an amoeboid-like morphology, by undergoing mesenchymal to amoeboid transition (MAT). We found that adhering cells producing spreading initiation centers (SIC), a transient structure localized above nascent adhesion complexes, share common biological and morphological characteristics associated with amoeboid cells. Meanwhile, spreading cells seem to return to a mesenchymal-like morphology. Thus, our results indicate that SIC-induced adhesion recapitulate events associated with amoeboid to mesenchymal transition (AMT). We found that polyadenylated RNAs were enriched within SIC and blocking their translation decreased adhesion potential of metastatic cells that progressed through EMT. These results point to a novel checkpoint regulating cell adhesion and allowing metastatic cells to alter adhesion strength in order to modulate their dissemination.
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Affiliation(s)
- Jonathan Bergeman
- Centre de Recherche sur le Cancer de l’Université Laval, Québec, Canada, G1R 3S3
| | - Alexia Caillier
- Centre de Recherche sur le Cancer de l’Université Laval, Québec, Canada, G1R 3S3
| | - François Houle
- CRCHU de Québec: Hôtel-Dieu de Québec; Québec, Canada, G1R 3S3
| | - Laurence M. Gagné
- Centre de Recherche sur le Cancer de l’Université Laval, Québec, Canada, G1R 3S3
| | - Marc-Étienne Huot
- Centre de Recherche sur le Cancer de l’Université Laval, Québec, Canada, G1R 3S3
- CRCHU de Québec: Hôtel-Dieu de Québec; Québec, Canada, G1R 3S3
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10
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Rai DK, Lawrence P, Kloc A, Schafer E, Rieder E. Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections. Virol J 2015; 12:224. [PMID: 26695943 PMCID: PMC4689063 DOI: 10.1186/s12985-015-0452-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/10/2015] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The nuclear protein Src-associated protein of 68 kDa in mitosis (Sam68) is known to bind RNA and be involved in cellular processes triggered in response to environmental stresses, including virus infection. Interestingly, Sam68 is a multi-functional protein implicated in the life cycle of retroviruses and picornaviruses and is also considered a marker of virus-induced stress granules (SGs). Recently, we demonstrated the partial redistribution of Sam68 to the cytoplasm in FMDV infected cells, its interaction with viral protease 3C(pro), and found a significant reduction in viral titers as consequence of Sam68-specific siRNA knockdowns. Despite of that, details of how it benefits FMDV remains to be elucidated. METHODS Sam68 cytoplasmic localization was examined by immunofluorescent microscopy, counterstaining with antibodies against Sam68, a viral capsid protein and markers of SGs. The relevance of RAAA motifs in the IRES was investigated using electromobility shift assays with Sam68 protein and parental and mutant FMDV RNAs. In addition, full genome WT and mutant or G-luc replicon RNAs were tested following transfection in mammalian cells. The impact of Sam68 depletion to virus protein and RNA synthesis was investigated in a cell-free system. Lastly, through co-immunoprecipitation, structural modeling, and subcellular fractionation, viral protein interactions with Sam68 were explored. RESULTS FMDV-induced cytoplasmic redistribution of Sam68 resulted in it temporarily co-localizing with SG marker: TIA-1. Mutations that disrupted FMDV IRES RAAA motifs, with putative affinity to Sam68 in domain 3 and 4 cause a reduction on the formation of ribonucleoprotein complexes with this protein and resulted in non-viable progeny viruses and replication-impaired replicons. Furthermore, depletion of Sam68 in cell-free extracts greatly diminished FMDV RNA replication, which was restored by addition of recombinant Sam68. The results here demonstrated that Sam68 specifically co-precipitates with both FMDV 3D(pol) and 3C(pro) consistent with early observations of FMDV 3C(pro)-induced cleavage of Sam68. CONCLUSION We have found that Sam68 is a specific binding partner for FMDV non-structural proteins 3C(pro) and 3D(pol) and showed that mutations at RAAA motifs in IRES domains 3 and 4 cause a decrease in Sam68 affinity to these RNA elements and rendered the mutant RNA non-viable. Interestingly, in FMDV infected cells re-localized Sam68 was transiently detected along with SG markers in the cytoplasm. These results support the importance of Sam68 as a host factor co-opted by FMDV during infection and demonstrate that Sam68 interact with both, FMDV RNA motifs in the IRES and viral non-structural proteins 3C(pro) and 3D(pol).
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Affiliation(s)
- Devendra K Rai
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Paul Lawrence
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Anna Kloc
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Elizabeth Schafer
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Elizabeth Rieder
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
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11
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SAM68: Signal Transduction and RNA Metabolism in Human Cancer. BIOMED RESEARCH INTERNATIONAL 2015; 2015:528954. [PMID: 26273626 PMCID: PMC4529925 DOI: 10.1155/2015/528954] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 02/24/2015] [Indexed: 12/21/2022]
Abstract
Alterations in expression and/or activity of splicing factors as well as mutations in cis-acting
splicing regulatory sequences contribute to cancer phenotypes. Genome-wide
studies have revealed more than 15,000 tumor-associated splice variants derived from
genes involved in almost every aspect of cancer cell biology, including proliferation,
differentiation, cell cycle control, metabolism, apoptosis, motility, invasion, and
angiogenesis. In the past decades, several RNA binding proteins (RBPs) have been
implicated in tumorigenesis. SAM68 (SRC associated in mitosis of 68 kDa) belongs to
the STAR (signal transduction and activation of RNA metabolism) family of RBPs.
SAM68 is involved in several steps of mRNA metabolism, from transcription to
alternative splicing and then to nuclear export. Moreover, SAM68 participates in signaling
pathways associated with cell response to stimuli, cell cycle transitions, and viral
infections. Recent evidence has linked this RBP to the onset and progression of
different tumors, highlighting misregulation of SAM68-regulated splicing events as a
key step in neoplastic transformation and tumor progression. Here we review recent
studies on the role of SAM68 in splicing regulation and we discuss its contribution to
aberrant pre-mRNA processing in cancer.
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12
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Sam68 Regulates S6K1 Alternative Splicing during Adipogenesis. Mol Cell Biol 2015; 35:1926-39. [PMID: 25776557 DOI: 10.1128/mcb.01488-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/11/2015] [Indexed: 01/13/2023] Open
Abstract
The requirement for alternative splicing during adipogenesis is poorly understood. The Sam68 RNA binding protein is a known regulator of alternative splicing, and mice deficient for Sam68 exhibit adipogenesis defects due to defective mTOR signaling. Sam68 null preadipocytes were monitored for alternative splicing imbalances in components of the mTOR signaling pathway. Herein, we report that Sam68 regulates isoform expression of the ribosomal S6 kinase gene (Rps6kb1). Sam68-deficient adipocytes express Rps6kb1-002 and its encoded p31S6K1 protein, in contrast to wild-type adipocytes that do not express this isoform. Sam68 binds an RNA sequence encoded by Rps6kb1 intron 6 and prevents serine/arginine-rich splicing factor 1 (SRSF1)-mediated alternative splicing of Rps6kb1-002, as assessed by cross-linking and immunoprecipitation (CLIP) and minigene assays. Depletion of p31S6K1 with small interfering RNAs (siRNAs) partially restored adipogenesis of Sam68-deficient preadipocytes. The ectopic expression of p31S6K1 in wild-type 3T3-L1 cells resulted in adipogenesis differentiation defects, showing that p31S6K1 is an inhibitor of adipogenesis. Our findings indicate that Sam68 is required to prevent the expression of p31S6K1 in adipocytes for adipogenesis to occur.
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13
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Beadell AV, Haag ES. Evolutionary Dynamics of GLD-1-mRNA complexes in Caenorhabditis nematodes. Genome Biol Evol 2014; 7:314-35. [PMID: 25502909 PMCID: PMC4316625 DOI: 10.1093/gbe/evu272] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/04/2014] [Indexed: 12/17/2022] Open
Abstract
Given the large number of RNA-binding proteins and regulatory RNAs within genomes, posttranscriptional regulation may be an underappreciated aspect of cis-regulatory evolution. Here, we focus on nematode germ cells, which are known to rely heavily upon translational control to regulate meiosis and gametogenesis. GLD-1 belongs to the STAR-domain family of RNA-binding proteins, conserved throughout eukaryotes, and functions in Caenorhabditis elegans as a germline-specific translational repressor. A phylogenetic analysis across opisthokonts shows that GLD-1 is most closely related to Drosophila How and deuterostome Quaking, both implicated in alternative splicing. We identify messenger RNAs associated with C. briggsae GLD-1 on a genome-wide scale and provide evidence that many participate in aspects of germline development. By comparing our results with published C. elegans GLD-1 targets, we detect nearly 100 that are conserved between the two species. We also detected several hundred Cbr-GLD-1 targets whose homologs have not been reported to be associated with C. elegans GLD-1 in either of two independent studies. Low expression in C. elegans may explain the failure to detect most of them, but a highly expressed subset are strong candidates for Cbr-GLD-1-specific targets. We examine GLD-1-binding motifs among targets conserved in C. elegans and C. briggsae and find that most, but not all, display evidence of shared ancestral binding sites. Our work illustrates both the conservative and the dynamic character of evolution at the posttranslational level of gene regulation, even between congeners.
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Affiliation(s)
- Alana V Beadell
- Program in Behavior, Evolution, Ecology, and Systematics, University of Maryland, College Park Present address: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, IL
| | - Eric S Haag
- Program in Behavior, Evolution, Ecology, and Systematics, University of Maryland, College Park Department of Biology, University of Maryland, College Park
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14
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Cappellari M, Bielli P, Paronetto MP, Ciccosanti F, Fimia GM, Saarikettu J, Silvennoinen O, Sette C. The transcriptional co-activator SND1 is a novel regulator of alternative splicing in prostate cancer cells. Oncogene 2014; 33:3794-802. [PMID: 23995791 DOI: 10.1038/onc.2013.360] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 06/03/2013] [Accepted: 07/05/2013] [Indexed: 01/12/2023]
Abstract
Splicing abnormalities have profound impact in human cancer. Several splicing factors, including SAM68, have pro-oncogenic functions, and their increased expression often correlates with human cancer development and progression. Herein, we have identified using mass spectrometry proteins that interact with endogenous SAM68 in prostate cancer (PCa) cells. Among other interesting proteins, we have characterized the interaction of SAM68 with SND1, a transcriptional co-activator that binds spliceosome components, thus coupling transcription and splicing. We found that both SAM68 and SND1 are upregulated in PCa cells with respect to benign prostate cells. Upregulation of SND1 exerts a synergic effect with SAM68 on exon v5 inclusion in the CD44 mRNA. The effect of SND1 on CD44 splicing required SAM68, as it was compromised after knockdown of this protein or mutation of the SAM68-binding sites in the CD44 pre-mRNA. More generally, we found that SND1 promotes the inclusion of CD44 variable exons by recruiting SAM68 and spliceosomal components on CD44 pre-mRNA. Inclusion of the variable exons in CD44 correlates with increased proliferation, motility and invasiveness of cancer cells. Strikingly, we found that knockdown of SND1, or SAM68, reduced proliferation and migration of PCa cells. Thus, our findings strongly suggest that SND1 is a novel regulator of alternative splicing that promotes PCa cell growth and survival.
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Affiliation(s)
- M Cappellari
- 1] Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy [2] Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - P Bielli
- 1] Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy [2] Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - M P Paronetto
- 1] Laboratory of Cellular and Molecular Neurobiology, Fondazione Santa Lucia, Rome, Italy [2] Department of Health Sciences, University of Rome Foro Italico, Rome, Italy
| | - F Ciccosanti
- Department of Epidemiology and Preclinical Research, National Institute for Infectious Diseases 'Lazzaro Spallanzani', Rome, Italy
| | - G M Fimia
- Department of Epidemiology and Preclinical Research, National Institute for Infectious Diseases 'Lazzaro Spallanzani', Rome, Italy
| | - J Saarikettu
- Laboratory of Molecular Immunology, School of Medicine and Institute of Biomedical Technology, Biomeditech, University of Tampere, Tampere, Finland
| | - O Silvennoinen
- 1] Laboratory of Molecular Immunology, School of Medicine and Institute of Biomedical Technology, Biomeditech, University of Tampere, Tampere, Finland [2] Department of Internal Medicine, Tampere University Hospital, Tampere, Finland
| | - C Sette
- 1] Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy [2] Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
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15
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Sánchez-Jiménez F, Sánchez-Margalet V. Role of Sam68 in post-transcriptional gene regulation. Int J Mol Sci 2013; 14:23402-19. [PMID: 24287914 PMCID: PMC3876053 DOI: 10.3390/ijms141223402] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/11/2013] [Accepted: 11/13/2013] [Indexed: 01/10/2023] Open
Abstract
The STAR family of proteins links signaling pathways to various aspects of post-transcriptional regulation and processing of RNAs. Sam68 belongs to this class of heteronuclear ribonucleoprotein particle K (hnRNP K) homology (KH) single domain-containing family of RNA-binding proteins that also contains some domains predicted to bind critical components in signal transduction pathways. In response to phosphorylation and other post-transcriptional modifications, Sam68 has been shown to have the ability to link signal transduction pathways to downstream effects regulating RNA metabolism, including transcription, alternative splicing or RNA transport. In addition to its function as a docking protein in some signaling pathways, this prototypic STAR protein has been identified to have a nuclear localization and to take part in the formation of both nuclear and cytosolic multi-molecular complexes such as Sam68 nuclear bodies and stress granules. Coupling with other proteins and RNA targets, Sam68 may play a role in the regulation of differential expression and mRNA processing and translation according to internal and external signals, thus mediating important physiological functions, such as cell death, proliferation or cell differentiation.
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Affiliation(s)
- Flora Sánchez-Jiménez
- Department of Medical Biochemistry and Molecular Biology and Immunology, UGC Clinical Biochemistry, Virgen Macarena University Hospital, Avenue. Sánchez Pizjuan 4, Medical School, University of Seville, Seville 41009, Spain.
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16
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Vogel G, Richard S. Emerging roles for Sam68 in adipogenesis and neuronal development. RNA Biol 2012; 9:1129-33. [PMID: 23018781 DOI: 10.4161/rna.21409] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Sam68, the Src-associated substrate during mitosis of 68 kDa, belongs to the large class of heteronuclear ribonucleoprotein particle K (hnRNP K) homology (KH) domain family of RNA-binding proteins. Sam68 contains a single KH domain harboring conserved N- and C-terminal sequences required for RNA binding and homodimerization. The KH domain is one of the most prevalent RNA binding domains that directly contacts single-stranded RNA. Sam68 has been implicated in numerous aspects of RNA metabolism including alternative splicing and polysomal recruitment of mRNAs. Studies in mice have revealed physiological roles linking Sam68 to osteoporosis, obesity, cancer, infertility and ataxia. Recent publications have greatly enhanced our understanding of Sam68 mechanism of action in addition to its cellular role. Herein, we will discuss the latest advances in the literature pertaining to obesity and neuronal development.
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Affiliation(s)
- Gillian Vogel
- Bloomfield Center for Research on Aging, Lady Davis Institute for Medical Research and Departments of Oncology and Medicine, McGill University, Montréal, QC Canada
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17
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Taguchi A, Politi K, Pitteri SJ, Lockwood WW, Faça VM, Kelly-Spratt K, Wong CH, Zhang Q, Chin A, Park KS, Goodman G, Gazdar AF, Sage J, Dinulescu DM, Kucherlapati R, DePinho RA, Kemp CJ, Varmus HE, Hanash SM. Lung cancer signatures in plasma based on proteome profiling of mouse tumor models. Cancer Cell 2011; 20:289-99. [PMID: 21907921 PMCID: PMC3406925 DOI: 10.1016/j.ccr.2011.08.007] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 07/06/2011] [Accepted: 08/05/2011] [Indexed: 12/23/2022]
Abstract
We investigated the potential of in-depth quantitative proteomics to reveal plasma protein signatures that reflect lung tumor biology. We compared plasma protein profiles of four mouse models of lung cancer with profiles of models of pancreatic, ovarian, colon, prostate, and breast cancer and two models of inflammation. A protein signature for Titf1/Nkx2-1, a known lineage-survival oncogene in lung cancer, was found in plasmas of mouse models of lung adenocarcinoma. An EGFR signature was found in plasma of an EGFR mutant model, and a distinct plasma signature related to neuroendocrine development was uncovered in the small-cell lung cancer model. We demonstrate relevance to human lung cancer of the protein signatures identified on the basis of mouse models.
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Affiliation(s)
- Ayumu Taguchi
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Katerina Politi
- Program in Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| | | | - William W. Lockwood
- Program in Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| | - Vitor M. Faça
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | | | - Chee-Hong Wong
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Qing Zhang
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Alice Chin
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Kwon-Sik Park
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Gary Goodman
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Adi F. Gazdar
- Hamon Center for Therapeutic Oncology Research and Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Julien Sage
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Daniela M. Dinulescu
- Eugene Braunwald Research Center, Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Raju Kucherlapati
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Ronald A. DePinho
- Belfer Institute for Applied Cancer Science, Department of Medical Oncology, Department of Medicine and Department of Genetics, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | | | - Harold E. Varmus
- Program in Cancer Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
| | - Samir M. Hanash
- Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
- Correspondence:
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Bielli P, Busà R, Paronetto MP, Sette C. The RNA-binding protein Sam68 is a multifunctional player in human cancer. Endocr Relat Cancer 2011; 18:R91-R102. [PMID: 21565971 DOI: 10.1530/erc-11-0041] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Src associated in mitosis, of 68 kDa (Sam68) is a KH domain RNA-binding protein that belongs to the signal transduction and activation of RNA family. Although ubiquitously expressed, Sam68 plays very specialized roles in different cellular environments. In most cells, Sam68 resides in the nucleus and is involved in several steps of mRNA processing, from transcription, to alternative splicing, to nuclear export. In addition, Sam68 translocates to the cytoplasm upon cell stimulation, cell cycle transitions or viral infections, where it takes part to signaling complexes and associates with the mRNA translation machinery. Recent evidence has linked Sam68 function to the onset and progression of endocrine tumors, such as prostate and breast carcinomas. Notably, all the biochemical activities reported for Sam68 seem to be implicated in carcinogenesis. Herein, we review the recent advancement in the knowledge of Sam68 function and regulation and discuss it in the frame of its participation to neoplastic transformation and tumor progression.
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Affiliation(s)
- Pamela Bielli
- Department of Public Health and Cell Biology, University of Rome Tor Vergata, Italy
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Locatelli A, Lange CA. Met receptors induce Sam68-dependent cell migration by activation of alternate extracellular signal-regulated kinase family members. J Biol Chem 2011; 286:21062-72. [PMID: 21489997 DOI: 10.1074/jbc.m110.211409] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The hepatocyte growth factor (HGF)/Met receptor signaling pathway is deregulated in diverse human malignancies and plays a central role in oncogenesis, tumor progression, and invasive cancer growth. Similarly, altered expression and splicing (i.e. inclusion of variant exon 5, "v5") of the cell adhesion marker, CD44, is associated with advanced cancer phenotypes. We sought to further understand how HGF regulates CD44v5 expression. Immortalized nontumorigenic keratinocyte (HaCaT) cells abundantly express both Met receptors and CD44v5 transmembrane glycoproteins. HGF stimulated CD44v5 protein expression and HaCaT cell migration; these events required activation of the ERK1/2 MAPK module and Sam68, a protein involved in RNA processing, splicing, and v5 inclusion. Similar to HaCaT cells, highly migratory MDA-MB-231 breast cancer cells also required Sam68 expression for HGF-induced migration. However, MDA-MB-231 cell migration occurred independently of ERK1/2 and CD44v5 expression and instead required ERK5 signaling to Sam68. Phospho-mutant, but not WT-Sam68, blocked HGF-induced cell migration in both cell types; MDA-MB-435 cells behaved similarly. These results suggest that Sam68 acts as a convergence point for ERK signaling to cell migration; blockade of phospho-Sam68 may provide a new avenue for therapeutic inhibition of metastatic cancers.
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Affiliation(s)
- Alessia Locatelli
- Department of Medicine (Division of Hematology, Oncology, and Transplantation), Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Tsai YJ, Pan H, Hung CM, Hou PT, Li YC, Lee YJ, Shen YT, Wu TT, Li C. The predominant protein arginine methyltransferase PRMT1 is critical for zebrafish convergence and extension during gastrulation. FEBS J 2011; 278:905-17. [PMID: 21214862 DOI: 10.1111/j.1742-4658.2011.08006.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein arginine methyltransferase (PRMT)1 is the predominant type I methyltransferase in mammals. In the present study, we used zebrafish (Danio rerio) as the model system to elucidate PRMT1 expression and function during embryogenesis. Zebrafish prmt1 transcripts were detected from the zygote period to the early larva stage. Knockdown of prmt1 by antisense morpholino oligo (AMO) resulted in delayed growth, shortened body-length, curled tails and cardiac edema. PRMT1 protein level, type I protein arginine methyltransferase activity, specific asymmetric protein arginine methylation and histone H4 R3 methylation all decreased in the AMO-injected morphants. The morphants showed defective convergence and extension and the abnormalities were more severe at the posterior than the anterior parts. Cell migration defects suggested by the phenotypes were not only observed in the morphant embryos, but also in a cellular prmt1 small-interfering RNA knockdown model. Rescue of the phenotypes by co-injection of wild-type but not catalytic defective prmt1 mRNA confirmed the specificity of the AMO and the requirement of methyltransferase activity in early development. The results obtained in the present study demonstrate a direct link of early development with protein arginine methylation catalyzed by PRMT1.
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Affiliation(s)
- Yun-Jung Tsai
- Department of Biomedical Sciences, Chung Shan Medical University, Taichung, Taiwan
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21
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Cunningham CL, Martínez Cerdeño V, Navarro Porras E, Prakash AN, Angelastro JM, Willemsen R, Hagerman PJ, Pessah IN, Berman RF, Noctor SC. Premutation CGG-repeat expansion of the Fmr1 gene impairs mouse neocortical development. Hum Mol Genet 2010; 20:64-79. [PMID: 20935171 DOI: 10.1093/hmg/ddq432] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late adult-onset neurodegenerative disorder caused by a premutation CGG-trinucleotide repeat expansion (55-200 CGG repeats) within the 5'-untranslated region of the FMR1 gene. Although FXTAS generally affects premutation carriers over 50 years of age, cognitive and psychological symptoms can appear in carriers during childhood, suggesting that the FMR1 premutation affects brain function early in life. Recent work with cultured hippocampal neurons from a premutation (Fmr1 CGG knock-in) mouse model revealed impaired development of early postnatal neurons, consistent with the developmental clinical involvement of premutation carriers. In the current work, we show that the presence of premutation CGG-repeat expansions in the mouse Fmr1 gene alters embryonic neocortical development. Specifically, embryonic premutation mice display migration defects in the neocortex and altered expression of neuronal lineage markers. The current data demonstrate that premutation alleles of the Fmr1 gene are associated with defects in developmental programs operating during prenatal stages of brain formation and provide further evidence that the FMR1 premutation has a neurodevelopmental component.
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Affiliation(s)
- Christopher L Cunningham
- Department of Pathology, Institute for Pediatric Regenerative Medicine--Shriners Hospital, School of Medicine, UC Davis, Sacramento, CA 95817, USA
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