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Cesari E, Farini D, Medici V, Ehrmann I, Guerra M, Testa E, Naro C, Geloso MC, Pagliarini V, La Barbera L, D’Amelio M, Orsini T, Vecchioli SF, Tamagnone L, Fort P, Viscomi MT, Elliott DJ, Sette C. Differential expression of paralog RNA binding proteins establishes a dynamic splicing program required for normal cerebral cortex development. Nucleic Acids Res 2024; 52:4167-4184. [PMID: 38324473 PMCID: PMC11077083 DOI: 10.1093/nar/gkae071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 01/17/2024] [Accepted: 01/25/2024] [Indexed: 02/09/2024] Open
Abstract
Sam68 and SLM2 are paralog RNA binding proteins (RBPs) expressed in the cerebral cortex and display similar splicing activities. However, their relative functions during cortical development are unknown. We found that these RBPs exhibit an opposite expression pattern during development. Sam68 expression declines postnatally while SLM2 increases after birth, and this developmental pattern is reinforced by hierarchical control of Sam68 expression by SLM2. Analysis of Sam68:Slm2 double knockout (Sam68:Slm2dko) mice revealed hundreds of exons that respond to joint depletion of these proteins. Moreover, parallel analysis of single and double knockout cortices indicated that exons regulated mainly by SLM2 are characterized by a dynamic splicing pattern during development, whereas Sam68-dependent exons are spliced at relatively constant rates. Dynamic splicing of SLM2-sensitive exons is completely suppressed in the Sam68:Slm2dko developing cortex. Sam68:Slm2dko mice die perinatally with defects in neurogenesis and in neuronal differentiation, and develop a hydrocephalus, consistent with splicing alterations in genes related to these biological processes. Thus, our study reveals that developmental control of separate Sam68 and Slm2 paralog genes encoding homologous RBPs enables the orchestration of a dynamic splicing program needed for brain development and viability, while ensuring a robust redundant mechanism that supports proper cortical development.
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Affiliation(s)
- Eleonora Cesari
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Largo Francesco Vito 1, 00168 Rome, Italy
- Fondazione Policlinico Agostino Gemelli IRCCS, Largo Agostino Gemelli, 00168 Rome, Italy
| | - Donatella Farini
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
- Fondazione Santa Lucia IRCCS, Via del Fosso di Fiorano, 64, 00143 Rome, Italy
| | - Vanessa Medici
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Largo Francesco Vito 1, 00168 Rome, Italy
| | - Ingrid Ehrmann
- Newcastle University Centre for Cancer, Newcastle University Institute of Biosciences, Newcastle NE1 3BZ, UK
| | - Marika Guerra
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Largo Francesco Vito 1, 00168 Rome, Italy
| | - Erika Testa
- Department of Life Science and Public Health, Section of Histology and Embryology, Catholic University of the Sacred Heart, Rome
| | - Chiara Naro
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Largo Francesco Vito 1, 00168 Rome, Italy
- Fondazione Policlinico Agostino Gemelli IRCCS, Largo Agostino Gemelli, 00168 Rome, Italy
| | - Maria Concetta Geloso
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Largo Francesco Vito 1, 00168 Rome, Italy
| | - Vittoria Pagliarini
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Largo Francesco Vito 1, 00168 Rome, Italy
- Fondazione Policlinico Agostino Gemelli IRCCS, Largo Agostino Gemelli, 00168 Rome, Italy
| | - Livia La Barbera
- Fondazione Santa Lucia IRCCS, Via del Fosso di Fiorano, 64, 00143 Rome, Italy
| | - Marcello D’Amelio
- Fondazione Santa Lucia IRCCS, Via del Fosso di Fiorano, 64, 00143 Rome, Italy
- Università Campus Bio-Medico di Roma, Via Álvaro del Portillo, 21, 00128 Rome, Italy
| | - Tiziana Orsini
- Institute of Biochemistry and Cell Biology, National Research Council (IBBC/CNR), Monterotondo, 00015 Rome, Italy
| | - Stefano Farioli Vecchioli
- Institute of Biochemistry and Cell Biology, National Research Council (IBBC/CNR), Monterotondo, 00015 Rome, Italy
| | - Luca Tamagnone
- Fondazione Policlinico Agostino Gemelli IRCCS, Largo Agostino Gemelli, 00168 Rome, Italy
- Department of Life Science and Public Health, Section of Histology and Embryology, Catholic University of the Sacred Heart, Rome
| | - Philippe Fort
- Centre de Recherche en Biologie Cellulaire de Montpellier, University of Montpellier, CNRS, 1919 Route de Mende, 34293 Montpellier Cedex 05, France
| | - Maria Teresa Viscomi
- Fondazione Policlinico Agostino Gemelli IRCCS, Largo Agostino Gemelli, 00168 Rome, Italy
- Department of Life Science and Public Health, Section of Histology and Embryology, Catholic University of the Sacred Heart, Rome
| | - David J Elliott
- Newcastle University Centre for Cancer, Newcastle University Institute of Biosciences, Newcastle NE1 3BZ, UK
| | - Claudio Sette
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, Largo Francesco Vito 1, 00168 Rome, Italy
- Fondazione Policlinico Agostino Gemelli IRCCS, Largo Agostino Gemelli, 00168 Rome, Italy
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Xu T, Li X, Zhao W, Wang X, Jin L, Feng Z, Li H, Zhang M, Tian Y, Hu G, Yue Y, Dai X, Shan C, Zhang W, Zhang C, Zhang Y. SF3B3-regulated mTOR alternative splicing promotes colorectal cancer progression and metastasis. J Exp Clin Cancer Res 2024; 43:126. [PMID: 38671459 PMCID: PMC11047005 DOI: 10.1186/s13046-024-03053-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 04/18/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND Aberrant alternative splicing (AS) is a pervasive event during colorectal cancer (CRC) development. SF3B3 is a splicing factor component of U2 small nuclear ribonucleoproteins which are crucial for early stages of spliceosome assembly. The role of SF3B3 in CRC remains unknown. METHODS SF3B3 expression in human CRCs was analyzed using publicly available CRC datasets, immunohistochemistry, qRT-PCR, and western blot. RNA-seq, RNA immunoprecipitation, and lipidomics were performed in SF3B3 knockdown or overexpressing CRC cell lines. CRC cell xenografts, patient-derived xenografts, patient-derived organoids, and orthotopic metastasis mouse models were utilized to determine the in vivo role of SF3B3 in CRC progression and metastasis. RESULTS SF3B3 was upregulated in CRC samples and associated with poor survival. Inhibition of SF3B3 by RNA silencing suppressed the proliferation and metastasis of CRC cells in vitro and in vivo, characterized by mitochondria injury, increased reactive oxygen species (ROS), and apoptosis. Mechanistically, silencing of SF3B3 increased mTOR exon-skipped splicing, leading to the suppression of lipogenesis via mTOR-SREBF1-FASN signaling. The combination of SF3B3 shRNAs and mTOR inhibitors showed synergistic antitumor activity in patient-derived CRC organoids and xenografts. Importantly, we identified SF3B3 as a critical regulator of mTOR splicing and autophagy in multiple cancers. CONCLUSIONS Our findings revealed that SF3B3 promoted CRC progression and metastasis by regulating mTOR alternative splicing and SREBF1-FASN-mediated lipogenesis, providing strong evidence to support SF3B3 as a druggable target for CRC therapy.
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Affiliation(s)
- Tong Xu
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China
| | - Xichuan Li
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin, 300382, China
| | - Wennan Zhao
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China
| | - Xue Wang
- Cancer Biology Program, University of Hawaii Cancer Center, Honolulu, HI, 96813, USA
| | - Leixin Jin
- Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, 30021, China
| | - Zhiqiang Feng
- Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, 30021, China
| | - Huixiang Li
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China
| | - Mingzhe Zhang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China
| | - Yiqing Tian
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China
| | - Ge Hu
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China
| | - Yuan Yue
- Tianjin Key Laboratory of Animal and Plant Resistance, College of Life Sciences, Tianjin Normal University, Tianjin, 300382, China
| | - Xintong Dai
- State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, 300350, China
| | - Changliang Shan
- State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin, 300350, China
| | | | - Chunze Zhang
- Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, 30021, China.
| | - Youcai Zhang
- School of Pharmaceutical Science and Technology, Tianjin University, Tianjin, 300072, China.
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da Silva AM, Yevdokimova V, Benoit YD. Sam68 is a druggable vulnerability point in cancer stem cells. Cancer Metastasis Rev 2024; 43:441-456. [PMID: 37792222 PMCID: PMC11016129 DOI: 10.1007/s10555-023-10145-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 09/27/2023] [Indexed: 10/05/2023]
Abstract
Sam68 (Src associated in mitosis of 68 kDa) is an RNA-binding and multifunctional protein extensively characterized in numerous cellular functions, such as RNA processing, cell cycle regulation, kinase- and growth factor signaling. Recent investigations highlighted Sam68 as a primary target of a class of reverse-turn peptidomimetic drugs, initially developed as inhibitors of Wnt/β-catenin mediated transcription. Further investigations on such compounds revealed their capacity to selectively eliminate cancer stem cell (CSC) activity upon engaging Sam68. This work highlighted previously unappreciated roles for Sam68 in the maintenance of neoplastic self-renewal and tumor-initiating functions. Here, we discuss the implication of Sam68 in tumorigenesis, where central findings support its contribution to chromatin regulation processes essential to CSCs. We also review advances in CSC-targeting drug discovery aiming to modulate Sam68 cellular distribution and protein-protein interactions. Ultimately, Sam68 constitutes a vulnerability point of CSCs and an attractive therapeutic target to impede neoplastic stemness in human tumors.
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Affiliation(s)
- Amanda Mendes da Silva
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Veronika Yevdokimova
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada
| | - Yannick D Benoit
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada.
- School of Pharmaceutical Sciences, Faculty of Medicine, University of Ottawa, Ottawa, ON, K1H 8M5, Canada.
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Malakar P, Shukla S, Mondal M, Kar RK, Siddiqui JA. The nexus of long noncoding RNAs, splicing factors, alternative splicing and their modulations. RNA Biol 2024; 21:1-20. [PMID: 38017665 PMCID: PMC10761143 DOI: 10.1080/15476286.2023.2286099] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2023] [Indexed: 11/30/2023] Open
Abstract
The process of alternative splicing (AS) is widely deregulated in a variety of cancers. Splicing is dependent upon splicing factors. Recently, several long noncoding RNAs (lncRNAs) have been shown to regulate AS by directly/indirectly interacting with splicing factors. This review focuses on the regulation of AS by lncRNAs through their interaction with splicing factors. AS mis-regulation caused by either mutation in splicing factors or deregulated expression of splicing factors and lncRNAs has been shown to be involved in cancer development and progression, making aberrant splicing, splicing factors and lncRNA suitable targets for cancer therapy. This review also addresses some of the current approaches used to target AS, splicing factors and lncRNAs. Finally, we discuss research challenges, some of the unanswered questions in the field and provide recommendations to advance understanding of the nexus of lncRNAs, AS and splicing factors in cancer.
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Affiliation(s)
- Pushkar Malakar
- Department of Biomedical Science and Technology, School of Biological Sciences, Ramakrishna Mission Vivekananda Educational Research Institute (RKMVERI), Kolkata, India
| | - Sudhanshu Shukla
- Department of Biosciences and Bioengineering, Indian Institute of Technology Dharwad, Dharwad, Karnataka, India
| | - Meghna Mondal
- Department of Biomedical Science and Technology, School of Biological Sciences, Ramakrishna Mission Vivekananda Educational Research Institute (RKMVERI), Kolkata, India
| | - Rajesh Kumar Kar
- Department of Neurosurgery, School of Medicine, Yale University, New Haven, CT, USA
| | - Jawed Akhtar Siddiqui
- Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA
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Liu X, Zheng Q, Wang K, Luo J, Wang Z, Li H, Liu Z, Dong N, Shi J. Sam68 promotes osteogenic differentiation of aortic valvular interstitial cells by TNF-α/STAT3/autophagy axis. J Cell Commun Signal 2023; 17:863-879. [PMID: 36847917 PMCID: PMC10409708 DOI: 10.1007/s12079-023-00733-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 02/10/2023] [Indexed: 03/01/2023] Open
Abstract
Calcified aortic valve disease (CAVD) is a major non-rheumatic heart valve disease in the world, with a high mortality rate and without suitable pharmaceutical therapy due to its complex mechanisms. Src-associated in mitosis 68-KD (Sam68), an RNA binding protein, has been reported as a signaling adaptor in numerous signaling pathways (Huot in Mol Cell Biol, 29(7), 1933-1943, 2009), particularly in inflammatory signaling pathways. The effects of Sam68 on the osteogenic differentiation process of hVICs and its regulation on signal transducer and activator of transcription 3 (STAT3) signaling pathway have been investigated in this study. Human aortic valve samples detection found that Sam68 expression was up-regulated in human calcific aortic valves. We used tumor necrosis factor α (TNF-α) as an activator for osteogenic differentiation in vitro and the result indicated that Sam68 was highly expressed after TNF-α stimulation. Overexpression of Sam68 promoted osteogenic differentiation of hVICs while Sam68 knockdown reversed this effect. Sam68 interaction with STAT3 was predicted by using String database and was verified in this study. Sam68 knockdown reduced phosphorylation of STAT3 activated by TNF-α and the downstream gene expression, which further influenced autophagy flux in hVICs. STAT3 knockdown alleviated the osteogenic differentiation and calcium deposition promoted by Sam68 overexpression. In conclusion, Sam68 interacts with STAT3 and participates in its phosphorylation to promote osteogenic differentiation of hVICs to induce valve calcification. Thus, Sam68 may be a new therapeutic target for CAVD. Regulatory of Sam68 in TNF-α/STAT3/Autophagy Axis in promoting osteogenesis of hVICs.
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Affiliation(s)
- Xing Liu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Qiang Zheng
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Kan Wang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Jinjing Luo
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Zhijie Wang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Huadong Li
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Zongtao Liu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Nianguo Dong
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
| | - Jiawei Shi
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei 430022 People’s Republic of China
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Sachse M, Tual-Chalot S, Ciliberti G, Amponsah-Offeh M, Stamatelopoulos K, Gatsiou A, Stellos K. RNA-binding proteins in vascular inflammation and atherosclerosis. Atherosclerosis 2023; 374:55-73. [PMID: 36759270 DOI: 10.1016/j.atherosclerosis.2023.01.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 12/01/2022] [Accepted: 01/12/2023] [Indexed: 01/19/2023]
Abstract
Atherosclerotic cardiovascular disease (ASCVD) remains the major cause of premature death and disability worldwide, even when patients with an established manifestation of atherosclerotic heart disease are optimally treated according to the clinical guidelines. Apart from the epigenetic control of transcription of the genetic information to messenger RNAs (mRNAs), gene expression is tightly controlled at the post-transcriptional level before the initiation of translation. Although mRNAs are traditionally perceived as the messenger molecules that bring genetic information from the nuclear DNA to the cytoplasmic ribosomes for protein synthesis, emerging evidence suggests that processes controlling RNA metabolism, driven by RNA-binding proteins (RBPs), affect cellular function in health and disease. Over the recent years, vascular endothelial cell, smooth muscle cell and immune cell RBPs have emerged as key co- or post-transcriptional regulators of several genes related to vascular inflammation and atherosclerosis. In this review, we provide an overview of cell-specific function of RNA-binding proteins involved in all stages of ASCVD and how this knowledge may be used for the development of novel precision medicine therapeutics.
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Affiliation(s)
- Marco Sachse
- Department of Cardiovascular Research, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Department of Cardiovascular Surgery, University Heart Center, University Hospital Hamburg Eppendorf, Hamburg, Germany
| | - Simon Tual-Chalot
- Biosciences Institute, Vascular Biology and Medicine Theme, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK.
| | - Giorgia Ciliberti
- Department of Cardiovascular Research, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislauf-Forschung, DZHK), Heidelberg/Mannheim Partner Site, Mannheim, Germany
| | - Michael Amponsah-Offeh
- Department of Cardiovascular Research, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislauf-Forschung, DZHK), Heidelberg/Mannheim Partner Site, Mannheim, Germany
| | - Kimon Stamatelopoulos
- Department of Clinical Therapeutics, Alexandra Hospital, National and Kapodistrian University of Athens School of Medicine, Athens, Greece
| | - Aikaterini Gatsiou
- Biosciences Institute, Vascular Biology and Medicine Theme, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK
| | - Konstantinos Stellos
- Department of Cardiovascular Research, European Center for Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany; Biosciences Institute, Vascular Biology and Medicine Theme, Faculty of Medical Sciences, Newcastle University, Newcastle Upon Tyne, UK; German Centre for Cardiovascular Research (Deutsches Zentrum für Herz-Kreislauf-Forschung, DZHK), Heidelberg/Mannheim Partner Site, Mannheim, Germany; Department of Cardiology, University Hospital Mannheim, Heidelberg University, Manheim, Germany.
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7
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Naing YT, Sun L. The Role of Splicing Factors in Adipogenesis and Thermogenesis. Mol Cells 2023; 46:268-277. [PMID: 37170770 PMCID: PMC10183792 DOI: 10.14348/molcells.2023.2195] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/27/2023] [Accepted: 03/03/2023] [Indexed: 05/13/2023] Open
Abstract
Obesity is a significant global health risk that can cause a range of serious metabolic problems, such as type 2 diabetes and cardiovascular diseases. Adipose tissue plays a pivotal role in regulating energy and lipid storage. New research has underlined the crucial role of splicing factors in the physiological and functional regulation of adipose tissue. By generating multiple transcripts from a single gene, alternative splicing allows for a greater diversity of the proteome and transcriptome, which subsequently influence adipocyte development and metabolism. In this review, we provide an outlook on the part of splicing factors in adipogenesis and thermogenesis, and investigate how the different spliced isoforms can affect the development and function of adipose tissue.
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Affiliation(s)
- Yadanar Than Naing
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore 169857
| | - Lei Sun
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore 169857
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8
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Qiao A, Ma W, Jiang Y, Han C, Yan B, Zhou J, Qin G. Hepatic Sam68 Regulates Systemic Glucose Homeostasis and Insulin Sensitivity. Int J Mol Sci 2022; 23:ijms231911469. [PMID: 36232770 PMCID: PMC9569775 DOI: 10.3390/ijms231911469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 09/19/2022] [Accepted: 09/21/2022] [Indexed: 11/21/2022] Open
Abstract
Hepatic glucose production (HGP) is an important component of glucose homeostasis, and deregulated HGP, particularly through gluconeogenesis, contributes to hyperglycemia and pathology of type-2 diabetes (T2D). It has been shown that the gluconeogenic gene expression is governed primarily by the transcription factor cAMP-response element (CRE)-binding protein (CREB) and its coactivator, CREB-regulated transcriptional coactivator 2 (CRTC2). Recently, we have discovered that Sam68, an adaptor protein and Src kinase substrate, potently promotes hepatic gluconeogenesis by promoting CRTC2 stability; however, the detailed mechanisms remain unclear. Here we show that in response to glucagon, Sam68 increases CREB/CRTC2 transactivity by interacting with CRTC2 in the CREB/CRTC2 complex and occupying the CRE motif of promoters, leading to gluconeogenic gene expression and glucose production. In hepatocytes, glucagon promotes Sam68 nuclear import, whereas insulin elicits its nuclear export. Furthermore, ablation of Sam68 in hepatocytes protects mice from high-fat diet (HFD)-induced hyperglycemia and significantly increased hepatic and peripheral insulin sensitivities. Thus, hepatic Sam68 potentiates CREB/CRTC2-mediated glucose production, contributes to the pathogenesis of insulin resistance, and may serve as a therapeutic target for T2D.
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Affiliation(s)
- Aijun Qiao
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Zhongshan Institute for Drug Discovery, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Zhongshan 528400, China
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China
- Correspondence: (A.Q.); (G.Q.); Tel.: +205-934-6690 (G.Q.); Fax: +205-934-9101 (G.Q.)
| | - Wenxia Ma
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ying Jiang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Chaoshan Han
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Baolong Yan
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Feinberg Cardiovascular Research Institute, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Correspondence: (A.Q.); (G.Q.); Tel.: +205-934-6690 (G.Q.); Fax: +205-934-9101 (G.Q.)
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DNA Damage Regulates the Functions of the RNA Binding Protein Sam68 through ATM-Dependent Phosphorylation. Cancers (Basel) 2022; 14:cancers14163847. [PMID: 36010841 PMCID: PMC9405969 DOI: 10.3390/cancers14163847] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 07/26/2022] [Accepted: 08/05/2022] [Indexed: 12/11/2022] Open
Abstract
Simple Summary Alterations of the complex network of interactions between the DNA damage response pathway and RNA metabolism have been described in several tumors, and increasing efforts are devoted to the elucidation of the molecular mechanisms involved in this network. Previous large-scale proteomic studies identified the RNA binding protein Sam68 as a putative target of the ATM kinase. Herein, we demonstrate that ATM phosphorylates Sam68 upon DNA damage induction, and this post-translational modification regulates both the signaling function of Sam68 in the initial phase of the DNA damage response and its RNA processing activity. Thus, our study uncovers anew crosstalk between ATM and Sam68, which may represent a paradigm for the functional interaction between the DDR pathway and RNA binding proteins, and a possible actionabletarget in human cancers. Abstract Cancer cells frequently exhibit dysregulation of the DNA damage response (DDR), genomic instability, and altered RNA metabolism. Recent genome-wide studies have strongly suggested an interaction between the pathways involved in the cellular response to DDR and in the regulation of RNA metabolism, but the molecular mechanism(s) involved in this crosstalk are largely unknown. Herein, we found that activation of the DDR kinase ATM promotes its interaction with Sam68, leading to phosphorylation of this multifunctional RNA binding protein (RBP) on three residues: threonine 61, serine 388 and serine 390. Moreover, we demonstrate that ATM-dependent phosphorylation of threonine 61 promotes the function of Sam68 in the DDR pathway and enhances its RNA processing activity. Importantly, ATM-mediated phosphorylation of Sam68 in prostate cancer cells modulates alternative polyadenylation of transcripts that are targets of Sam68, supporting the notion that the ATM–Sam68 axis exerts a multifaceted role in the response to DNA damage. Thus, our work validates Sam68 as an ATM kinase substrate and uncovers an unexpected bidirectional interplay between ATM and Sam68, which couples the DDR pathway to modulation of RNA metabolism in response to genotoxic stress.
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RNA-Binding Proteins in the Regulation of Adipogenesis and Adipose Function. Cells 2022; 11:cells11152357. [PMID: 35954201 PMCID: PMC9367552 DOI: 10.3390/cells11152357] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 01/27/2023] Open
Abstract
The obesity epidemic represents a critical public health issue worldwide, as it is a vital risk factor for many diseases, including type 2 diabetes (T2D) and cardiovascular disease. Obesity is a complex disease involving excessive fat accumulation. Proper adipose tissue accumulation and function are highly transcriptional and regulated by many genes. Recent studies have discovered that post-transcriptional regulation, mainly mediated by RNA-binding proteins (RBPs), also plays a crucial role. In the lifetime of RNA, it is bound by various RBPs that determine every step of RNA metabolism, from RNA processing to alternative splicing, nucleus export, rate of translation, and finally decay. In humans, it is predicted that RBPs account for more than 10% of proteins based on the presence of RNA-binding domains. However, only very few RBPs have been studied in adipose tissue. The primary aim of this paper is to provide an overview of RBPs in adipogenesis and adipose function. Specifically, the following best-characterized RBPs will be discussed, including HuR, PSPC1, Sam68, RBM4, Ybx1, Ybx2, IGF2BP2, and KSRP. Characterization of these proteins will increase our understanding of the regulatory mechanisms of RBPs in adipogenesis and provide clues for the etiology and pathology of adipose-tissue-related diseases.
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11
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Dogan AE, Hamid SM, Yildirim AD, Yildirim Z, Sen G, Riera CE, Gottlieb RA, Erbay E. PACT establishes a posttranscriptional brake on mitochondrial biogenesis by promoting the maturation of miR-181c. J Biol Chem 2022; 298:102050. [PMID: 35598827 PMCID: PMC9218515 DOI: 10.1016/j.jbc.2022.102050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 11/29/2022] Open
Abstract
The double-stranded RNA-dependent protein kinase activating protein (PACT), an RNA-binding protein that is part of the RNA-induced silencing complex, plays a key role in miR-mediated translational repression. Previous studies showed that PACT regulates the expression of various miRs, selects the miR strand to be loaded onto RNA-induced silencing complex, and determines proper miR length. Apart from PACT's role in mediating the antiviral response in immune cells, what PACT does in other cell types is unknown. Strikingly, it has also been shown that cold exposure leads to marked downregulation of PACT protein in mouse brown adipose tissue (BAT), where mitochondrial biogenesis and metabolism play a central role. Here, we show that PACT establishes a posttranscriptional brake on mitochondrial biogenesis (mitobiogenesis) by promoting the maturation of miR-181c, a key suppressor of mitobiogenesis that has been shown to target mitochondrial complex IV subunit I (Mtco1) and sirtuin 1 (Sirt1). Consistently, we found that a partial reduction in PACT expression is sufficient to enhance mitobiogenesis in brown adipocytes in culture as well as during BAT activation in mice. In conclusion, we demonstrate an unexpected role for PACT in the regulation of mitochondrial biogenesis and energetics in cells and BAT.
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Affiliation(s)
- Asli E Dogan
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Molecular Biology and Genetics, National Nanotechnology Center, Bilkent University, Ankara, Turkey
| | - Syed M Hamid
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Asli D Yildirim
- Department of Molecular Biology and Genetics, National Nanotechnology Center, Bilkent University, Ankara, Turkey
| | - Zehra Yildirim
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Molecular Biology and Genetics, National Nanotechnology Center, Bilkent University, Ankara, Turkey
| | - Ganes Sen
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Celine E Riera
- Department of Biomedical Sciences, Center for Neural Science and Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA; Department of Neurology, Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA; David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | - Roberta A Gottlieb
- Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ebru Erbay
- David Geffen School of Medicine, University of California, Los Angeles, California, USA; Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA.
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12
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Zhang W, Liu L, Zhao S, Chen L, Wei Y, Chen W, Ge F. Research progress on RNA‑binding proteins in breast cancer (Review). Oncol Lett 2022; 23:121. [PMID: 35261635 PMCID: PMC8867207 DOI: 10.3892/ol.2022.13241] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 02/03/2022] [Indexed: 11/28/2022] Open
Abstract
Breast cancer is the most common malignancy among women, and the abnormal regulation of gene expression serves an important role in its occurrence and development. However, the molecular mechanisms underlying gene expression are highly complex and heterogeneous, and RNA-binding proteins (RBPs) are among the key regulatory factors. RBPs bind targets in an environment-dependent or environment-independent manner to influence mRNA stability and the translation of genes involved in the formation, progression, metastasis and treatment of breast cancer. Due to the growing interest in these regulators, the present review summarizes the most influential studies concerning RBPs associated with breast cancer to elucidate the role of RBPs in breast cancer and to assess how they interact with other key pathways to provide new molecular targets for the diagnosis and treatment of breast cancer.
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Affiliation(s)
- Wenzhu Zhang
- Department of Breast Surgery, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650032, P.R. China
| | - Linlin Liu
- School of Forensic Medicine, Kunming Medical University, Kunming, Yunnan 650500, P.R. China
| | - Shengdi Zhao
- Department of Breast Surgery, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650032, P.R. China
| | - Liang Chen
- Department of Breast Surgery, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650032, P.R. China
| | - Yuxian Wei
- Department of Endocrine Breast Surgery, First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Wenlin Chen
- Third Department of Breast Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650118, P.R. China
| | - Fei Ge
- Department of Breast Surgery, First Affiliated Hospital of Kunming Medical University, Kunming, Yunnan 650032, P.R. China
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13
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Abstract
In Eukarya, immature mRNA transcripts (pre-mRNA) often contain coding sequences, or exons, interleaved by non-coding sequences, or introns. Introns are removed upon splicing, and further regulation of the retained exons leads to alternatively spliced mRNA. The splicing reaction requires the stepwise assembly of the spliceosome, a macromolecular machine composed of small nuclear ribonucleoproteins (snRNPs). This review focuses on the early stage of spliceosome assembly, when U1 snRNP defines each intron 5’-splice site (5ʹss) in the pre-mRNA. We first introduce the splicing reaction and the impact of alternative splicing on gene expression regulation. Thereafter, we extensively discuss splicing descriptors that influence the 5ʹss selection by U1 snRNP, such as sequence determinants, and interactions mediated by U1-specific proteins or U1 small nuclear RNA (U1 snRNA). We also include examples of diseases that affect the 5ʹss selection by U1 snRNP, and discuss recent therapeutic advances that manipulate U1 snRNP 5ʹss selectivity with antisense oligonucleotides and small-molecule splicing switches.
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Affiliation(s)
- Florian Malard
- Inserm U1212, CNRS UMR5320, ARNA Laboratory, University of Bordeaux, Bordeaux Cedex, France
| | - Cameron D Mackereth
- Inserm U1212, CNRS UMR5320, ARNA Laboratory, University of Bordeaux, Bordeaux Cedex, France
| | - Sébastien Campagne
- Inserm U1212, CNRS UMR5320, ARNA Laboratory, University of Bordeaux, Bordeaux Cedex, France
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14
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Feng J, Ren X, Fu H, Li D, Chen X, Zu X, Liu Q, Wu M. LRRC4 mediates the formation of circular RNA CD44 to inhibitGBM cell proliferation. MOLECULAR THERAPY-NUCLEIC ACIDS 2021; 26:473-487. [PMID: 34631278 PMCID: PMC8479294 DOI: 10.1016/j.omtn.2021.08.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Accepted: 08/20/2021] [Indexed: 11/19/2022]
Abstract
Mounting evidence reveals that dysregulation of circular RNAs (circRNAs) is involved in the development of glioblastoma. Leucine-rich repeat-containing 4 (LRRC4) has been shown to suppress tumors in glioblastoma. However, whether LRRC4 can regulate the formation of circRNA is not yet understood. In this study, LRRC4 was found to interact with SAM68. LRRC4 promoted the generation of circCD44 by inhibiting the binding between SAM68 and CD44 pre-mRNA. Moreover, downregulated expression of circCD44 was found in glioblastoma multiforme (GBM) tissues and GBM primary cells. Re-expression of circCD44 significantly suppressed the proliferation, colony formation, and invasion of GBM cells and inhibited tumor growth in vivo. Mechanistically, circCD44 could regulate the expression of SMAD6 via sponging miR-326 and miR-330-5p involved in the progression of GBM. Thus, the LRRC4/SAM68/circCD44/miR-326/miR-330-5p/SMAD6 signaling axis could be a potential target for GBM treatment.
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Affiliation(s)
- Jianbo Feng
- Cancer Research Institute, First Affiliated Hospital, Institute of Clinical Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, Hunan 410078, China
| | - Xing Ren
- Cancer Research Institute, First Affiliated Hospital, Institute of Clinical Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China
| | - Haijuan Fu
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, Hunan 410078, China
| | - Di Li
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, Hunan 410078, China
| | - Xiguang Chen
- Cancer Research Institute, First Affiliated Hospital, Institute of Clinical Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China
| | - Xuyu Zu
- Cancer Research Institute, First Affiliated Hospital, Institute of Clinical Medicine, Hengyang Medical School, University of South China, Hengyang, Hunan 421001, China
| | - Qing Liu
- Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan 410013, China
- Corresponding author: Qing Liu, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Xiangya Hospital, Central South University, Changsha, Hunan 410013, China.
| | - Minghua Wu
- Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, Hunan 410078, China
- Corresponding author: Minghua Wu, Cancer Research Institute, School of Basic Medical Science, Central South University, Changsha, Hunan 410078, China.
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15
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Qiao A, Ma W, Deng J, Zhou J, Han C, Zhang E, Boriboun C, Xu S, Zhang C, Jie C, Kim JA, Habegger KM, Qiu H, Zhao TC, Zhang J, Qin G. Ablation of Sam68 in adult mice increases thermogenesis and energy expenditure. FASEB J 2021; 35:e21772. [PMID: 34252225 DOI: 10.1096/fj.202100021r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 05/27/2021] [Accepted: 06/17/2021] [Indexed: 12/18/2022]
Abstract
Genetic deletion of Src associated in mitosis of 68kDa (Sam68), a pleiotropic adaptor protein prevents high-fat diet-induced weight gain and insulin resistance. To clarify the role of Sam68 in energy metabolism in the adult stage, we generated an inducible Sam68 knockout mice. Knockout of Sam68 was induced at the age of 7-10 weeks, and then we examined the metabolic profiles of the mice. Sam68 knockout mice gained less body weight over time and at 34 or 36 weeks old, had smaller fat mass without changes in food intake and absorption efficiency. Deletion of Sam68 in mice elevated thermogenesis, increased energy expenditure, and attenuated core-temperature drop during acute cold exposure. Furthermore, we examined younger Sam68 knockout mice at 11 weeks old before their body weights deviate, and confirmed increased energy expenditure and thermogenic gene program. Thus, Sam68 is essential for the control of adipose thermogenesis and energy homeostasis in the adult.
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Affiliation(s)
- Aijun Qiao
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Wenxia Ma
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jianxin Deng
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Chaoshan Han
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Eric Zhang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chan Boriboun
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Shiyue Xu
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chunxiang Zhang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chunfa Jie
- Department of Biochemistry and Nutrition, Des Moines University College of Osteopathic Medicine, Des Moines, IA, USA
| | - Jeong-A Kim
- Department of Medicine-Endocrinology, Diabetes & Metabolism, Comprehensive Diabetes Center, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Kirk M Habegger
- Department of Medicine-Endocrinology, Diabetes & Metabolism, Comprehensive Diabetes Center, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science, Georgia State University, Atlanta, GA, USA
| | - Ting C Zhao
- Department of Surgery, Boston University Medical School, Roger Williams Medical Center, Providence, RI, USA
| | - Jianyi Zhang
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, School of Medicine and School of Engineering, University of Alabama at Birmingham, Birmingham, AL, USA.,Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
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16
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Qiao A, Zhou J, Xu S, Ma W, Boriboun C, Kim T, Yan B, Deng J, Yang L, Zhang E, Song Y, Ma YC, Richard S, Zhang C, Qiu H, Habegger KM, Zhang J, Qin G. Sam68 promotes hepatic gluconeogenesis via CRTC2. Nat Commun 2021; 12:3340. [PMID: 34099657 PMCID: PMC8185084 DOI: 10.1038/s41467-021-23624-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Hepatic gluconeogenesis is essential for glucose homeostasis and also a therapeutic target for type 2 diabetes, but its mechanism is incompletely understood. Here, we report that Sam68, an RNA-binding adaptor protein and Src kinase substrate, is a novel regulator of hepatic gluconeogenesis. Both global and hepatic deletions of Sam68 significantly reduce blood glucose levels and the glucagon-induced expression of gluconeogenic genes. Protein, but not mRNA, levels of CRTC2, a crucial transcriptional regulator of gluconeogenesis, are >50% lower in Sam68-deficient hepatocytes than in wild-type hepatocytes. Sam68 interacts with CRTC2 and reduces CRTC2 ubiquitination. However, truncated mutants of Sam68 that lack the C- (Sam68ΔC) or N-terminal (Sam68ΔN) domains fails to bind CRTC2 or to stabilize CRTC2 protein, respectively, and transgenic Sam68ΔN mice recapitulate the blood-glucose and gluconeogenesis profile of Sam68-deficient mice. Hepatic Sam68 expression is also upregulated in patients with diabetes and in two diabetic mouse models, while hepatocyte-specific Sam68 deficiencies alleviate diabetic hyperglycemia and improves insulin sensitivity in mice. Thus, our results identify a role for Sam68 in hepatic gluconeogenesis, and Sam68 may represent a therapeutic target for diabetes. Hepatic gluconeogenesis is important for glucose homeostasis and a therapeutic target for type 2 diabetes. Here, the authors show that the RNA-binding adaptor protein Sam68 promotes the expression level of gluconeogenic genes and increases blood glucose levels by stabilizing the transcriptional coactivator CRTC2, while hepatic Sam68 deletion alleviates hyperglycemia in mice.
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Affiliation(s)
- Aijun Qiao
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Junlan Zhou
- Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Shiyue Xu
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Wenxia Ma
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Chan Boriboun
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Teayoun Kim
- Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, School of Medicine, Birmingham, AL, USA
| | - Baolong Yan
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Jianxin Deng
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Liu Yang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Eric Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Yuhua Song
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Yongchao C Ma
- Departments of Pediatrics, Neurology and Physiology, Northwestern University Feinberg School of Medicine, Anne & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Stephane Richard
- Lady Davis Institute for Medical Research, McGill University, Montreal, QC, Canada
| | - Chunxiang Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Hongyu Qiu
- Center for Molecular and Translational Medicine, Institute of Biomedical Science Georgia State University, Atlanta, GA, USA
| | - Kirk M Habegger
- Department of Medicine - Endocrinology, Diabetes & Metabolism, University of Alabama at Birmingham, School of Medicine, Birmingham, AL, USA
| | - Jianyi Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA
| | - Gangjian Qin
- Department of Biomedical Engineering, University of Alabama at Birmingham, School of Medicine and School of Engineering, Birmingham, AL, USA. .,Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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17
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Regulation of cold-induced thermogenesis by the RNA binding protein FAM195A. Proc Natl Acad Sci U S A 2021; 118:2104650118. [PMID: 34088848 DOI: 10.1073/pnas.2104650118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Homeothermic vertebrates produce heat in cold environments through thermogenesis, in which brown adipose tissue (BAT) increases mitochondrial oxidation along with uncoupling of the electron transport chain and activation of uncoupling protein 1 (UCP1). Although the transcription factors regulating the expression of UCP1 and nutrient oxidation genes have been extensively studied, only a few other proteins essential for BAT function have been identified. We describe the discovery of FAM195A, a BAT-enriched RNA binding protein, which is required for cold-dependent thermogenesis in mice. FAM195A knockout (KO) mice display whitening of BAT and an inability to thermoregulate. In BAT of FAM195A KO mice, enzymes involved in branched-chain amino acid (BCAA) metabolism are down-regulated, impairing their response to cold. Knockdown of FAM195A in brown adipocytes in vitro also impairs expression of leucine oxidation enzymes, revealing FAM195A to be a regulator of BCAA metabolism and a potential target for metabolic disorders.
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18
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Chao Y, Jiang Y, Zhong M, Wei K, Hu C, Qin Y, Zuo Y, Yang L, Shen Z, Zou C. Regulatory roles and mechanisms of alternative RNA splicing in adipogenesis and human metabolic health. Cell Biosci 2021; 11:66. [PMID: 33795017 PMCID: PMC8017860 DOI: 10.1186/s13578-021-00581-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/24/2021] [Indexed: 12/15/2022] Open
Abstract
Alternative splicing (AS) regulates gene expression patterns at the post-transcriptional level and generates a striking expansion of coding capacities of genomes and cellular protein diversity. RNA splicing could undergo modulation and close interaction with genetic and epigenetic machinery. Notably, during the adipogenesis processes of white, brown and beige adipocytes, AS tightly interplays with the differentiation gene program networks. Here, we integrate the available findings on specific splicing events and distinct functions of different splicing regulators as examples to highlight the directive biological contribution of AS mechanism in adipogenesis and adipocyte biology. Furthermore, accumulating evidence has suggested that mutations and/or altered expression in splicing regulators and aberrant splicing alterations in the obesity-associated genes are often linked to humans’ diet-induced obesity and metabolic dysregulation phenotypes. Therefore, significant attempts have been finally made to overview novel detailed discussion on the prospects of splicing machinery with obesity and metabolic disorders to supply featured potential management mechanisms in clinical applicability for obesity treatment strategies.
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Affiliation(s)
- Yunqi Chao
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Yonghui Jiang
- Department of Genetics, Yale University School of Medicine, New Haven, CT, 06520, USA
| | - Mianling Zhong
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Kaiyan Wei
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Chenxi Hu
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Yifang Qin
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Yiming Zuo
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Lili Yang
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Zheng Shen
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China
| | - Chaochun Zou
- Department of Endocrinology, The Children's Hospital, School of Medicine, Zhejiang University, Hangzhou, 310052, Zhejiang, China.
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19
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Angarola BL, Anczuków O. Splicing alterations in healthy aging and disease. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021. [PMID: 33565261 DOI: 10.1002/wrna.1643.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alternative RNA splicing is a key step in gene expression that allows generation of numerous messenger RNA transcripts encoding proteins of varied functions from the same gene. It is thus a rich source of proteomic and functional diversity. Alterations in alternative RNA splicing are observed both during healthy aging and in a number of human diseases, several of which display premature aging phenotypes or increased incidence with age. Age-associated splicing alterations include differential splicing of genes associated with hallmarks of aging, as well as changes in the levels of core spliceosomal genes and regulatory splicing factors. Here, we review the current known links between alternative RNA splicing, its regulators, healthy biological aging, and diseases associated with aging or aging-like phenotypes. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA.,Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA.,Institute for Systems Genomics, UConn Health, Farmington, Connecticut, USA
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20
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Ondrej M, Cechakova L, Fabrik I, Klimentova J, Tichy A. Lys05 - A Promising Autophagy Inhibitor in the Radiosensitization Battle: Phosphoproteomic Perspective. Cancer Genomics Proteomics 2021; 17:369-382. [PMID: 32576582 DOI: 10.21873/cgp.20196] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/13/2020] [Accepted: 03/17/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Autophagy is a crucial factor contributing to radioresistance during radiotherapy. Although Lys05 has proven its ability to improve the results of radiotherapy through the inhibition of autophagy, molecular mechanisms of this inhibition remain elusive. We aimed to describe the molecular mechanisms involved in Lys05-induced inhibition of autophagy. MATERIALS AND METHODS Radioresistant human non-small cell lung carcinoma cells (H1299, p53-negative) and methods of quantitative phosphoproteomics were employed to define the molecular mechanisms involved in Lys05-induced inhibition of autophagy. RESULTS We confirmed that at an early stage after irradiation, autophagy was induced, whereas at a later stage after irradiation, it was inhibited. The early-stage induction of autophagy was characterized mainly by the activation of biosynthetic and metabolic processes through up- or down-regulation of the critical autophagic regulatory proteins Sequestosome-1 (SQSTM1) and proline-rich AKT1 substrate 1 (AKT1S1). The late-stage inhibition of autophagy was attributed mainly to down-regulation of Unc-51 like autophagy-activating kinase 1 (ULK1) through phosphorylation at Ser638. CONCLUSION This work contributes to emerging phosphoproteomic insights into autophagy-mediated global signaling in lung cancer cells, which might consequently facilitate the development of precision medicine therapeutics.
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Affiliation(s)
- Martin Ondrej
- Department of Radiobiology, Faculty of Military Health Sciences, University of Defense in Brno, Hradec Kralove, Czech Republic
| | - Lucie Cechakova
- Department of Radiobiology, Faculty of Military Health Sciences, University of Defense in Brno, Hradec Kralove, Czech Republic
| | - Ivo Fabrik
- Department of Molecular Biology and Pathology, Faculty of Military Health Sciences, University of Defense in Brno, Hradec Kralove, Czech Republic
| | - Jana Klimentova
- Department of Molecular Biology and Pathology, Faculty of Military Health Sciences, University of Defense in Brno, Hradec Kralove, Czech Republic
| | - Ales Tichy
- Department of Radiobiology, Faculty of Military Health Sciences, University of Defense in Brno, Hradec Kralove, Czech Republic
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21
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Angarola BL, Anczuków O. Splicing alterations in healthy aging and disease. WILEY INTERDISCIPLINARY REVIEWS-RNA 2021; 12:e1643. [PMID: 33565261 DOI: 10.1002/wrna.1643] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 12/19/2022]
Abstract
Alternative RNA splicing is a key step in gene expression that allows generation of numerous messenger RNA transcripts encoding proteins of varied functions from the same gene. It is thus a rich source of proteomic and functional diversity. Alterations in alternative RNA splicing are observed both during healthy aging and in a number of human diseases, several of which display premature aging phenotypes or increased incidence with age. Age-associated splicing alterations include differential splicing of genes associated with hallmarks of aging, as well as changes in the levels of core spliceosomal genes and regulatory splicing factors. Here, we review the current known links between alternative RNA splicing, its regulators, healthy biological aging, and diseases associated with aging or aging-like phenotypes. This article is categorized under: RNA in Disease and Development > RNA in Disease RNA Processing > Splicing Regulation/Alternative Splicing.
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Affiliation(s)
| | - Olga Anczuków
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA.,Department of Genetics and Genome Sciences, UConn Health, Farmington, Connecticut, USA.,Institute for Systems Genomics, UConn Health, Farmington, Connecticut, USA
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22
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De Paola E, Forcina L, Pelosi L, Pisu S, La Rosa P, Cesari E, Nicoletti C, Madaro L, Mercatelli N, Biamonte F, Nobili A, D'Amelio M, De Bardi M, Volpe E, Caporossi D, Sette C, Musarò A, Paronetto MP. Sam68 splicing regulation contributes to motor unit establishment in the postnatal skeletal muscle. Life Sci Alliance 2020; 3:3/10/e201900637. [PMID: 32753528 PMCID: PMC7409371 DOI: 10.26508/lsa.201900637] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 07/23/2020] [Accepted: 07/24/2020] [Indexed: 01/08/2023] Open
Abstract
Sam68 ensures the establishment of neuromuscular junctions (NMJs) and motor unit integrity by orchestrating a neuronal splicing program. RNA-binding proteins orchestrate the composite life of RNA molecules and impact most physiological processes, thus underlying complex phenotypes. The RNA-binding protein Sam68 regulates differentiation processes by modulating splicing, polyadenylation, and stability of select transcripts. Herein, we found that Sam68−/− mice display altered regulation of alternative splicing in the spinal cord of key target genes involved in synaptic functions. Analysis of the motor units revealed that Sam68 ablation impairs the establishment of neuromuscular junctions and causes progressive loss of motor neurons in the spinal cord. Importantly, alterations of neuromuscular junction morphology and properties in Sam68−/− mice correlate with defects in muscle and motor unit integrity. Sam68−/− muscles display defects in postnatal development, with manifest signs of atrophy. Furthermore, fast-twitch muscles in Sam68−/− mice show structural features typical of slow-twitch muscles, suggesting alterations in the metabolic and functional properties of myofibers. Collectively, our data identify a key role for Sam68 in muscle development and suggest that proper establishment of motor units requires timely expression of synaptic splice variants.
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Affiliation(s)
- Elisa De Paola
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy.,IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Laura Forcina
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Laura Pelosi
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Simona Pisu
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Piergiorgio La Rosa
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Eleonora Cesari
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy.,Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome, Italy
| | - Carmine Nicoletti
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Luca Madaro
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome, Italy
| | - Neri Mercatelli
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy.,IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Filippo Biamonte
- Institute of Biochemistry and Clinical Biochemistry, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Annalisa Nobili
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy.,Department of Medicine, University Campus-Biomedico, Rome, Italy
| | - Marcello D'Amelio
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy.,Department of Medicine, University Campus-Biomedico, Rome, Italy
| | - Marco De Bardi
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Elisabetta Volpe
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
| | - Daniela Caporossi
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy
| | - Claudio Sette
- IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy .,Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Heart, Rome, Italy
| | - Antonio Musarò
- Laboratory Affiliated to Istituto Pasteur-Fondazione Cenci Bolognetti, DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Maria Paola Paronetto
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico," Rome, Italy .,IRCCS (Institute for Treatment and Research) Fondazione Santa Lucia, Rome, Italy
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23
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Park JW, Fu S, Huang B, Xu RH. Alternative splicing in mesenchymal stem cell differentiation. Stem Cells 2020; 38:1229-1240. [PMID: 32627865 PMCID: PMC7586970 DOI: 10.1002/stem.3248] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/03/2020] [Accepted: 06/11/2020] [Indexed: 01/07/2023]
Abstract
The differentiation and maturation of mesenchymal stem cells (MSCs) to mesodermal and other lineages are known to be controlled by various extrinsic and intrinsic signals. The dysregulation of the MSC differentiation balance has been linked to several pathophysiological conditions, including obesity and osteoporosis. Previous research of the molecular mechanisms governing MSC differentiation has mostly focused on transcriptional regulation. However, recent findings are revealing the underrated role of alternative splicing (AS) in MSC differentiation and functions. In this review, we discuss recent progress in elucidating the regulatory roles of AS in MSC differentiation. We catalogue and highlight the key AS events that modulate MSC differentiation to major osteocytes, chondrocytes, and adipocytes, and discuss the regulatory mechanisms by which AS is regulated.
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Affiliation(s)
- Jung Woo Park
- Center for Reproduction, Development, and Aging and Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, People's Republic of China
| | - Siyi Fu
- Center for Reproduction, Development, and Aging and Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, People's Republic of China
| | - Borong Huang
- Center for Reproduction, Development, and Aging and Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, People's Republic of China
| | - Ren-He Xu
- Center for Reproduction, Development, and Aging and Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, People's Republic of China
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24
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Naro C, Pellegrini L, Jolly A, Farini D, Cesari E, Bielli P, de la Grange P, Sette C. Functional Interaction between U1snRNP and Sam68 Insures Proper 3' End Pre-mRNA Processing during Germ Cell Differentiation. Cell Rep 2020; 26:2929-2941.e5. [PMID: 30865884 DOI: 10.1016/j.celrep.2019.02.058] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 01/15/2019] [Accepted: 02/14/2019] [Indexed: 01/02/2023] Open
Abstract
Male germ cells express the widest repertoire of transcript variants in mammalian tissues. Nevertheless, factors and mechanisms underlying such pronounced diversity are largely unknown. The splicing regulator Sam68 is highly expressed in meiotic cells, and its ablation results in defective spermatogenesis. Herein, we uncover an extensive splicing program operated by Sam68 across meiosis, primarily characterized by alternative last exon (ALE) regulation in genes of functional relevance for spermatogenesis. Lack of Sam68 preferentially causes premature transcript termination at internal polyadenylation sites, a feature observed also upon depletion of the spliceosomal U1snRNP in somatic cells. Notably, Sam68-regulated ALEs are characterized by proximity between U1snRNP and Sam68 binding motifs. We demonstrate a physical association between Sam68 and U1snRNP and show that U1snRNP recruitment to Sam68-regulated ALEs is impaired in Sam68-/- germ cells. Thus, our study reveals an unexpected cooperation between Sam68 and U1snRNP that insures proper processing of transcripts essential for male fertility.
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Affiliation(s)
- Chiara Naro
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Hearth, 00168 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Livia Pellegrini
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Ariane Jolly
- GenoSplice Technology, iPEPS-ICM, Hôpital de la Pitié Salpêtrière, 75013 Paris, France
| | - Donatella Farini
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Eleonora Cesari
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Hearth, 00168 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Pamela Bielli
- Department of Biomedicine and Prevention, University of Rome "Tor Vergata," 00133 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
| | - Pierre de la Grange
- GenoSplice Technology, iPEPS-ICM, Hôpital de la Pitié Salpêtrière, 75013 Paris, France
| | - Claudio Sette
- Institute of Human Anatomy and Cell Biology, Catholic University of the Sacred Hearth, 00168 Rome, Italy; IRCCS Fondazione Santa Lucia, 00143 Rome, Italy.
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25
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Siang DTC, Lim YC, Kyaw AMM, Win KN, Chia SY, Degirmenci U, Hu X, Tan BC, Walet ACE, Sun L, Xu D. The RNA-binding protein HuR is a negative regulator in adipogenesis. Nat Commun 2020; 11:213. [PMID: 31924774 PMCID: PMC6954112 DOI: 10.1038/s41467-019-14001-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 12/04/2019] [Indexed: 12/12/2022] Open
Abstract
Human antigen R (HuR) is an essential regulator of RNA metabolism, but its function in metabolism remains unclear. This study identifies HuR as a major repressor during adipogenesis. Knockdown and overexpression of HuR in primary adipocyte culture enhances and inhibits adipogenesis in vitro, respectively. Fat-specific knockout of HuR significantly enhances adipogenic gene program in adipose tissues, accompanied by a systemic glucose intolerance and insulin resistance. HuR knockout also results in depot-specific phenotypes: it can repress myogenesis program in brown fat, enhance inflammation program in epidydimal white fat and induce browning program in inguinal white fat. Mechanistically, HuR may inhibit adipogenesis by recognizing and modulating the stability of hundreds of adipocyte transcripts including Insig1, a negative regulator during adipogenesis. Taken together, our work establishes HuR as an important posttranscriptional regulator of adipogenesis and provides insights into how RNA processing contributes to adipocyte development.
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Affiliation(s)
- Diana Teh Chee Siang
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Yen Ching Lim
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Aung Maung Maung Kyaw
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Khaing Nwe Win
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Sook Yoong Chia
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Ufuk Degirmenci
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Xiang Hu
- Departments of Endocrine and Metabolic Diseases, The first Affiliated Hospital of Wenzhou Medical University, Wenzhou, , Zhejiang, 325035, China
| | - Bryan C Tan
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Arcinas Camille Esther Walet
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore
| | - Lei Sun
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore. .,Institute of Molecular and Cell Biology, 61 Biopolis Drive, Proteos, Singapore, 138673, Singapore.
| | - Dan Xu
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, 8 College Road, Singapore, 169857, Singapore.
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26
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Lu H, Ye Z, Zhai Y, Wang L, Liu Y, Wang J, Zhang W, Luo W, Lu Z, Chen J. QKI regulates adipose tissue metabolism by acting as a brake on thermogenesis and promoting obesity. EMBO Rep 2020; 21:e47929. [PMID: 31868295 PMCID: PMC6944952 DOI: 10.15252/embr.201947929] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 10/22/2019] [Accepted: 11/08/2019] [Indexed: 12/31/2022] Open
Abstract
Adipose tissue controls numerous physiological processes, and its dysfunction has a causative role in the development of systemic metabolic disorders. The role of posttranscriptional regulation in adipose metabolism has yet to be fully understood. Here, we show that the RNA-binding protein quaking (QKI) plays an important role in controlling metabolic homeostasis of the adipose tissue. QKI-deficient mice are resistant to high-fat-diet (HFD)-induced obesity. Additionally, QKI depletion increased brown fat energy dissipation and browning of subcutaneous white fat. Adipose tissue-specific depletion of QKI in mice enhances cold-induced thermogenesis, thereby preventing hypothermia in response to cold stimulus. Further mechanistic analysis reveals that QKI is transcriptionally induced by the cAMP-cAMP response element-binding protein (CREB) axis and restricts adipose tissue energy consumption by decreasing stability, nuclear export, and translation of mRNAs encoding UCP1 and PGC1α. These findings extend our knowledge of the significance of posttranscriptional regulation in adipose metabolic homeostasis and provide a potential therapeutic target to defend against obesity and its related metabolic diseases.
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Affiliation(s)
- Huanyu Lu
- Department of Occupational and Environmental Healththe Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anChina
| | - Zichen Ye
- State Key Laboratory of Cancer BiologyDepartment of PharmacogenomicsSchool of PharmacyFourth Military Medical UniversityXi'anChina
| | - Yue Zhai
- Department of Cell BiologyFourth Military Medical UniversityXi'anChina
| | - Li Wang
- State Key Laboratory of Cancer BiologyDepartment of PharmacogenomicsSchool of PharmacyFourth Military Medical UniversityXi'anChina
| | - Ying Liu
- Department of Occupational and Environmental Healththe Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anChina
| | - Jiye Wang
- Department of Occupational and Environmental Healththe Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anChina
| | - Wenbin Zhang
- Department of Occupational and Environmental Healththe Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anChina
| | - Wenjing Luo
- Department of Occupational and Environmental Healththe Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anChina
| | - Zifan Lu
- State Key Laboratory of Cancer BiologyDepartment of PharmacogenomicsSchool of PharmacyFourth Military Medical UniversityXi'anChina
| | - Jingyuan Chen
- Department of Occupational and Environmental Healththe Ministry of Education Key Lab of Hazard Assessment and Control in Special Operational EnvironmentSchool of Public HealthFourth Military Medical UniversityXi'anChina
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27
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Zhang K, Yang X, Zhao Q, Li Z, Fu F, Zhang H, Zheng M, Zhang S. Molecular Mechanism of Stem Cell Differentiation into Adipocytes and Adipocyte Differentiation of Malignant Tumor. Stem Cells Int 2020; 2020:8892300. [PMID: 32849880 PMCID: PMC7441422 DOI: 10.1155/2020/8892300] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/07/2020] [Accepted: 07/27/2020] [Indexed: 02/07/2023] Open
Abstract
Adipogenesis is the process through which preadipocytes differentiate into adipocytes. During this process, the preadipocytes cease to proliferate, begin to accumulate lipid droplets, and develop morphologic and biochemical characteristics of mature adipocytes. Mesenchymal stem cells (MSCs) are a type of adult stem cells known for their high plasticity and capacity to generate mesodermal and nonmesodermal tissues. Many mature cell types can be generated from MSCs, including adipocyte, osteocyte, and chondrocyte. The differentiation of stem cells into multiple mature phenotypes is at the basis for tissue regeneration and repair. Cancer stem cells (CSCs) play a very important role in tumor development and have the potential to differentiate into multiple cell lineages. Accumulating evidence has shown that cancer cells can be induced to differentiate into various benign cells, such as adipocytes, fibrocytes, osteoblast, by a variety of small molecular compounds, which may provide new strategies for cancer treatment. Recent studies have reported that tumor cells undergoing epithelial-to-mesenchymal transition can be induced to differentiate into adipocytes. In this review, molecular mechanisms, signal pathways, and the roles of various biological processes in adipose differentiation are summarized. Understanding the molecular mechanism of adipogenesis and adipose differentiation of cancer cells may contribute to cancer treatments that involve inducing differentiation into benign cells.
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Affiliation(s)
- Kexin Zhang
- 1Department of Pathology, Tianjin Union Medical Center, Tianjin, China
- 2Nankai University School of Medicine, Nankai University, Tianjin, China
| | - Xudong Yang
- 3Tianjin Rehabilitation Center, Tianjin, China
| | - Qi Zhao
- 1Department of Pathology, Tianjin Union Medical Center, Tianjin, China
| | - Zugui Li
- 1Department of Pathology, Tianjin Union Medical Center, Tianjin, China
- 4Graduate School, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Fangmei Fu
- 1Department of Pathology, Tianjin Union Medical Center, Tianjin, China
- 4Graduate School, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Hao Zhang
- 1Department of Pathology, Tianjin Union Medical Center, Tianjin, China
- 4Graduate School, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Minying Zheng
- 1Department of Pathology, Tianjin Union Medical Center, Tianjin, China
| | - Shiwu Zhang
- 1Department of Pathology, Tianjin Union Medical Center, Tianjin, China
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28
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Bhadra M, Howell P, Dutta S, Heintz C, Mair WB. Alternative splicing in aging and longevity. Hum Genet 2019; 139:357-369. [PMID: 31834493 DOI: 10.1007/s00439-019-02094-6] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 11/24/2019] [Indexed: 12/13/2022]
Abstract
Alternative pre-mRNA splicing increases the complexity of the proteome that can be generated from the available genomic coding sequences. Dysregulation of the splicing process has been implicated in a vast repertoire of diseases. However, splicing has recently been linked to both the aging process itself and pro-longevity interventions. This review focuses on recent research towards defining RNA splicing as a new hallmark of aging. We highlight dysfunctional alternative splicing events that contribute to the aging phenotype across multiple species, along with recent efforts toward deciphering mechanistic roles for RNA splicing in the regulation of aging and longevity. Further, we discuss recent research demonstrating a direct requirement for specific splicing factors in pro-longevity interventions, and specifically how nutrient signaling pathways interface to splicing factor regulation and downstream splicing targets. Finally, we review the emerging potential of using splicing profiles as a predictor of biological age and life expectancy. Understanding the role of RNA splicing components and downstream targets altered in aging may provide opportunities to develop therapeutics and ultimately extend healthy lifespan in humans.
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Affiliation(s)
- Malini Bhadra
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Porsha Howell
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Sneha Dutta
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Caroline Heintz
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA
| | - William B Mair
- Department of Molecular Metabolism, Harvard T.H. Chan School of Public Health, Boston, MA, 02115, USA.
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29
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Subramania S, Gagné LM, Campagne S, Fort V, O'Sullivan J, Mocaer K, Feldmüller M, Masson JY, Allain FHT, Hussein SM, Huot MÉ. SAM68 interaction with U1A modulates U1 snRNP recruitment and regulates mTor pre-mRNA splicing. Nucleic Acids Res 2019; 47:4181-4197. [PMID: 30767021 PMCID: PMC6486544 DOI: 10.1093/nar/gkz099] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/14/2019] [Accepted: 02/05/2019] [Indexed: 12/11/2022] Open
Abstract
Src associated in mitosis (SAM68) plays major roles in regulating RNA processing events, such as alternative splicing and mRNA translation, implicated in several developmental processes. It was previously shown that SAM68 regulates the alternative splicing of the mechanistic target of rapamycin (mTor), but the mechanism regulating this process remains elusive. Here, we report that SAM68 interacts with U1 small nuclear ribonucleoprotein (U1 snRNP) to promote splicing at the 5′ splice site in intron 5 of mTor. We also show that this direct interaction is mediated through U1A, a core-component of U1snRNP. SAM68 was found to bind the RRM1 domain of U1A through its C-terminal tyrosine rich region (YY domain). Deletion of the U1A-SAM68 interaction domain or mutation in SAM68-binding sites in intron 5 of mTor abrogates U1A recruitment and 5′ splice site recognition by the U1 snRNP, leading to premature intron 5 termination and polyadenylation. Taken together, our results provide the first mechanistic study by which SAM68 modulates alternative splicing decision, by affecting U1 snRNP recruitment at 5′ splice sites.
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Affiliation(s)
- Suryasree Subramania
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Laurence M Gagné
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Sébastien Campagne
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Victoire Fort
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Julia O'Sullivan
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Karel Mocaer
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada
| | - Miki Feldmüller
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Jean-Yves Masson
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Frédéric H T Allain
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Samer M Hussein
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
| | - Marc-Étienne Huot
- Centre de recherche du CHU de Québec-Université Laval (axe Oncologie), Québec, QC G1R 3S3, Canada.,CRCHU de Québec - Axe Oncologie, Québec, QC G1R 3S3, Canada
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30
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Iijima Y, Tanaka M, Suzuki S, Hauser D, Tanaka M, Okada C, Ito M, Ayukawa N, Sato Y, Ohtsuka M, Scheiffele P, Iijima T. SAM68-Specific Splicing Is Required for Proper Selection of Alternative 3' UTR Isoforms in the Nervous System. iScience 2019; 22:318-335. [PMID: 31805436 PMCID: PMC6909182 DOI: 10.1016/j.isci.2019.11.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/09/2019] [Accepted: 11/13/2019] [Indexed: 12/22/2022] Open
Abstract
Neuronal alternative splicing is a core mechanism for functional diversification. We previously found that STAR family proteins (SAM68, SLM1, SLM2) regulate spatiotemporal alternative splicing in the nervous system. However, the whole aspect of alternative splicing programs by STARs remains unclear. Here, we performed a transcriptomic analysis using SAM68 knockout and SAM68/SLM1 double-knockout midbrains. We revealed different alternative splicing activity between SAM68 and SLM1; SAM68 preferentially targets alternative 3′ UTR exons. SAM68 knockout causes a long-to-short isoform switch of a number of neuronal targets through the alteration in alternative last exon (ALE) selection or alternative polyadenylation. The altered ALE usage of a novel target, interleukin 1 receptor accessory protein (Il1rap), results in remarkable conversion from a membrane-bound type to a secreted type in Sam68KO brains. Proper ALE selection is necessary for IL1RAP neuronal function. Thus the SAM68-specific splicing program provides a mechanism for neuronal selection of alternative 3′ UTR isoforms. SAM68 and the related protein SLM1 exhibit distinct alternative splicing activity SAM68 specifically controls 3′ UTR selection of multiple neuronal genes Proper 3′ UTR selection is necessary for IL1RAP neuronal function Neuronal expression of SAM68 requires proper 3′ UTR selection in the nervous system
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Affiliation(s)
- Yoko Iijima
- Tokai University Institute of Innovative Science and Technology, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan; Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, School of Medicine, Tokai University, 143, Shimokasuya, Isehara, Kanagawa 259-1193, Japan
| | - Masami Tanaka
- Tokai University Institute of Innovative Science and Technology, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan
| | - Satoko Suzuki
- Tokai University Institute of Innovative Science and Technology, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan
| | - David Hauser
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, Basel 4056, Switzerland
| | - Masayuki Tanaka
- The Support Center for Medical Research and Education, Tokai University, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan
| | - Chisa Okada
- The Support Center for Medical Research and Education, Tokai University, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan
| | - Masatoshi Ito
- The Support Center for Medical Research and Education, Tokai University, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan
| | - Noriko Ayukawa
- Tokai University Institute of Innovative Science and Technology, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan
| | - Yuji Sato
- Tokai University Institute of Innovative Science and Technology, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan; Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, School of Medicine, Tokai University, 143, Shimokasuya, Isehara, Kanagawa 259-1193, Japan
| | - Masato Ohtsuka
- Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, School of Medicine, Tokai University, 143, Shimokasuya, Isehara, Kanagawa 259-1193, Japan
| | - Peter Scheiffele
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, Basel 4056, Switzerland
| | - Takatoshi Iijima
- Tokai University Institute of Innovative Science and Technology, 143 Shimokasuya, Isehara City, Kanagawa 259-1193, Japan; Department of Molecular Life Science, Division of Basic Medical Science and Molecular Medicine, School of Medicine, Tokai University, 143, Shimokasuya, Isehara, Kanagawa 259-1193, Japan.
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The Oncogene Metadherin Interacts with the Known Splicing Proteins YTHDC1, Sam68 and T-STAR and Plays a Novel Role in Alternative mRNA Splicing. Cancers (Basel) 2019; 11:cancers11091233. [PMID: 31450747 PMCID: PMC6770463 DOI: 10.3390/cancers11091233] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 08/13/2019] [Accepted: 08/21/2019] [Indexed: 11/16/2022] Open
Abstract
Oncogenic metadherin is a key contributor to tumourigenesis with metadherin expression and cytoplasmic localisation previously linked to poor survival. A number of reports have shown metadherin localises specifically to nuclear speckles known to be rich in RNA-binding proteins including the splicing proteins YTHDC1, Sam68 and T-STAR, that have been shown to select alternative splice sites in mRNA of tumour-associated proteins including BRCA, MDM2 and VEGF. Here we investigate the interaction and relationship between metadherin and the splice factors YTHDC1, T-STAR and Sam68. Using a yeast two-hybrid assay and immunoprecipitation we show that metadherin interacts with YTHDC1, Sam68 and T-STAR and demonstrate that T-STAR is significantly overexpressed in prostate cancer tissue compared to benign prostate tissue. We also demonstrate that metadherin influences splice site selection in a dose-dependent manner in CD44v5-luc minigene reporter assays. Finally, we demonstrate that prostate cancer patients with higher metadherin expression have greater expression of the CD44v5 exon. CD44v5 expression could be used to discriminate patients with poor outcomes following radical prostatectomy. In this work we show for the first time that metadherin interacts with, and modulates, the function of key components of splicing associated with cancer development and progression.
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Ortiz-Sánchez P, Villalba-Orero M, López-Olañeta MM, Larrasa-Alonso J, Sánchez-Cabo F, Martí-Gómez C, Camafeita E, Gómez-Salinero JM, Ramos-Hernández L, Nielsen PJ, Vázquez J, Müller-McNicoll M, García-Pavía P, Lara-Pezzi E. Loss of SRSF3 in Cardiomyocytes Leads to Decapping of Contraction-Related mRNAs and Severe Systolic Dysfunction. Circ Res 2019; 125:170-183. [PMID: 31145021 PMCID: PMC6615931 DOI: 10.1161/circresaha.118.314515] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE RBPs (RNA binding proteins) play critical roles in the cell by regulating mRNA transport, splicing, editing, and stability. The RBP SRSF3 (serine/arginine-rich splicing factor 3) is essential for blastocyst formation and for proper liver development and function. However, its role in the heart has not been explored. OBJECTIVE To investigate the role of SRSF3 in cardiac function. METHODS AND RESULTS Cardiac SRSF3 expression was high at mid gestation and decreased during late embryonic development. Mice lacking SRSF3 in the embryonic heart showed impaired cardiomyocyte proliferation and died in utero. In the adult heart, SRSF3 expression was reduced after myocardial infarction, suggesting a possible role in cardiac homeostasis. To determine the role of this RBP in the adult heart, we used an inducible, cardiomyocyte-specific SRSF3 knockout mouse model. After SRSF3 depletion in cardiomyocytes, mice developed severe systolic dysfunction that resulted in death within 8 days. RNA-Seq analysis revealed downregulation of mRNAs encoding sarcomeric and calcium handling proteins. Cardiomyocyte-specific SRSF3 knockout mice also showed evidence of alternative splicing of mTOR (mammalian target of rapamycin) mRNA, generating a shorter protein isoform lacking catalytic activity. This was associated with decreased phosphorylation of 4E-BP1 (eIF4E-binding protein 1), a protein that binds to eIF4E (eukaryotic translation initiation factor 4E) and prevents mRNA decapping. Consequently, we found increased decapping of mRNAs encoding proteins involved in cardiac contraction. Decapping was partially reversed by mTOR activation. CONCLUSIONS We show that cardiomyocyte-specific loss of SRSF3 expression results in decapping of critical mRNAs involved in cardiac contraction. The molecular mechanism underlying this effect likely involves the generation of a short mTOR isoform by alternative splicing, resulting in reduced 4E-BP1 phosphorylation. The identification of mRNA decapping as a mechanism of systolic heart failure may open the way to the development of urgently needed therapeutic tools.
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Affiliation(s)
- Paula Ortiz-Sánchez
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.).,Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, Madrid, Spain (P.O.-S., P.G.-P.)
| | - María Villalba-Orero
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Marina M López-Olañeta
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Javier Larrasa-Alonso
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Fátima Sánchez-Cabo
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Carlos Martí-Gómez
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Emilio Camafeita
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Jesús M Gómez-Salinero
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Laura Ramos-Hernández
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.)
| | - Peter J Nielsen
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany (P.J.N.)
| | - Jesús Vázquez
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.).,Centro de Investigacion Biomedica en Red Cardiovascular (CIBERCV), Madrid, Spain (J.V., P.G.-P., E.L.-P)
| | - Michaela Müller-McNicoll
- Goethe-University Frankfurt, Institute of Cell Biology and Neuroscience, Frankfurt/Main, Germany (M.M.-M.)
| | - Pablo García-Pavía
- Heart Failure and Inherited Cardiac Diseases Unit, Department of Cardiology, Hospital Universitario Puerta de Hierro, Madrid, Spain (P.O.-S., P.G.-P.).,Centro de Investigacion Biomedica en Red Cardiovascular (CIBERCV), Madrid, Spain (J.V., P.G.-P., E.L.-P).,Facultad de Ciencias de la Salud, Universidad Francisco de Vitoria (UFV), Pozuelo de Alarcón, Madrid, Spain (P.G.-P.)
| | - Enrique Lara-Pezzi
- From the Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain (P.O.-S., M.V.-O., M.M.L.-O., J.L.-A., F.S.-C., C.M.-G., E.C., J.M.G.-S., L.R.-H., J.V., E.L.-P.).,Centro de Investigacion Biomedica en Red Cardiovascular (CIBERCV), Madrid, Spain (J.V., P.G.-P., E.L.-P).,National Heart and Lung Institute, Imperial College London, United Kingdom (E.L.-P.)
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The RNA binding protein Sam68 controls T helper 1 differentiation and anti-mycobacterial response through modulation of miR-29. Cell Death Differ 2018; 26:1169-1180. [PMID: 30258098 DOI: 10.1038/s41418-018-0201-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/08/2018] [Accepted: 08/27/2018] [Indexed: 12/24/2022] Open
Abstract
Polarization of naive T cells into interferon (IFN)-γ-producing T helper 1 (Th1) cells is an essential event in the inflammatory response to pathogens. Herein, we identify the RNA binding protein Sam68 as a specific modulator of Th1 differentiation. Sam68-knockout (ko) naive T cells are strongly defective in IL-12-mediated Th1 polarization and express low levels of T-bet and Eomes. Consequently, Sam68-ko Th1 cells are significantly impaired in IFN-γ production. Moreover, we found that Sam68 is required for the induction of an inflammatory Th1 response during Mycobacterium bovis Bacillus Calmette-Guerin (BCG) infection, thus limiting bacterial dissemination in the lungs. Mechanistically, Sam68 directly binds to the microRNA miR-29, a negative regulator of Th1 response, and inhibits its expression during BCG infection. These findings uncover a novel post-transcriptional mechanism required for the Th1-mediated defense against intracellular pathogens and identify a new function for Sam68 in the regulation of the immune response.
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Li JB, Zhang R, Han X, Piao CL. Ginsenoside Rg1 inhibits dietary-induced obesity and improves obesity-related glucose metabolic disorders. ACTA ACUST UNITED AC 2018. [PMID: 29513799 PMCID: PMC5856439 DOI: 10.1590/1414-431x20177139] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Obesity and its consequent type 2 diabetes are significant threats to global health. Emerging evidence indicates that ginsenosides from ginseng (Panax ginseng) have anti-diabetic activity. We hypothesized that ginsenosides Rg1 could suppress dietary-induced obesity and improve obesity-related glucose metabolic disorders. Our results showed that ginsenoside Rg1 attenuated dietary-induced body weight gain and fat accumulation in white adipocyte tissue of mice fed a high-fat diet. Furthermore, we found that ginsenosides Rg1 not only decreased fasting glucose concentration and the 2-h postprandial glucose concentration, but also improved insulin resistance and glucose intolerance in those mice. Ginsenoside Rg1 also activated the AMPK pathway in vitro and in vivo and increased plasma membrane translocation of GLUT4 in C2C12 skeletal muscle cells. In conclusion, our observations suggested that ginsenoside Rg1 inhibited dietary-induced obesity and improved obesity-related insulin resistance and glucose intolerance by activation of the AMPK pathway.
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Affiliation(s)
- Jin-Bo Li
- Department of Endocrinology, Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, China
| | - Rui Zhang
- Department of Endocrinology, Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, China
| | - Xiao Han
- Department of Endocrinology, Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, China
| | - Chun-Li Piao
- Department of Endocrinology, Affiliated Hospital of Changchun University of Chinese Medicine, Changchun, China
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36
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Li N, Ngo CTA, Aleynikova O, Beauchemin N, Richard S. The p53 status can influence the role of Sam68 in tumorigenesis. Oncotarget 2018; 7:71651-71659. [PMID: 27690217 PMCID: PMC5342108 DOI: 10.18632/oncotarget.12305] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 09/20/2016] [Indexed: 02/02/2023] Open
Abstract
The expression and activities of RNA binding proteins are frequently dysregulated in human cancer. Their roles, however, appears to be complex, with reports indicating both pro-tumorigenic and tumor suppressive functions. Here we show, using two classical mouse cancer models, that the role of KH-type RNA binding protein, Sam68, in tumor development can be influenced by the status of the p53 tumor suppressor. We demonstrate that in mice expressing wild type p53, Sam68-deficiency resulted in a higher incidence and malignancy of carcinogen-induced tumors, suggesting a tumor suppressive role for Sam68. In marked contrast, Sam68-haploinsufficiency significantly delayed the onset of tumors in mice lacking p53 and prolonged their survival, indicating that Sam68 accelerates the development of p53-deficient tumors. These findings provide considerable insight into a previously unknown relationship between Sam68 and the p53 tumor suppressor in tumorigenesis.
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Affiliation(s)
- Naomi Li
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Chau Tuan-Anh Ngo
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Olga Aleynikova
- Department of Pathology, Jewish General Hospital, Montréal, Québec H3T 1E2, Canada
| | - Nicole Beauchemin
- Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Biochemistry, McGill University, Montréal, Québec H3G 1Y6, Canada.,Rosalind and Morris Goodman Cancer Centre, Montréal, Québec H3A 1A3, Canada
| | - Stéphane Richard
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine and Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
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Xiao J, Wang Q, Yang Q, Wang H, Qiang F, He S, Cai J, Yang L, Wang Y. Clinical significance and effect of Sam68 expression in gastric cancer. Oncol Lett 2018; 15:4745-4752. [PMID: 29552114 PMCID: PMC5840748 DOI: 10.3892/ol.2018.7930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2016] [Accepted: 08/11/2017] [Indexed: 12/26/2022] Open
Abstract
Gastric cancer is one of the most common types of malignancy worldwide. However, the molecular mechanisms of cancer development remain unclear. Src-associated in mitosis of 68 kDa (Sam68) is involved in cell proliferation, transformation, tumorigenesis and metastasis in several types of cancer. The present study aimed to assess the expression and function of Sam68 in human gastric cancer. Western blot analysis and immunohistochemistry indicated that Sam68 expression was increased in tumor samples and the levels were associated with the grade of malignancy. High Sam68 expression was associated with the poor prognosis of patients with gastric cancer. In vitro, following knockdown of Sam68 by transfection of gastric cancer cells with small interfering RNA, the cell viability, cell cycle progress, migration and invasion were decreased. The results of the present study revealed that Sam68 may be a novel prognostic factor for, and is associated with cell growth, migration and invasion in, gastric cancer.
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Affiliation(s)
- Jinzhang Xiao
- Department of Internal Oncology Medicine, Affiliated Nantong Cancer Hospital, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Qiuhong Wang
- Department of Internal Oncology Medicine, Affiliated Nantong Cancer Hospital, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Qichang Yang
- The Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Hua Wang
- The Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Fulin Qiang
- Department of Internal Oncology Medicine, Affiliated Nantong Cancer Hospital, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Song He
- Department of Internal Oncology Medicine, Affiliated Nantong Cancer Hospital, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Jin Cai
- Department of Internal Oncology Medicine, Affiliated Nantong Cancer Hospital, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Lei Yang
- Department of Internal Oncology Medicine, Affiliated Nantong Cancer Hospital, Nantong University, Nantong, Jiangsu 226000, P.R. China
| | - Yingying Wang
- The Jiangsu Province Key Laboratory for Inflammation and Molecular Drug Target, Nantong University, Nantong, Jiangsu 226000, P.R. China
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38
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Xu D, Xu S, Kyaw AMM, Lim YC, Chia SY, Chee Siang DT, Alvarez-Dominguez JR, Chen P, Leow MKS, Sun L. RNA Binding Protein Ybx2 Regulates RNA Stability During Cold-Induced Brown Fat Activation. Diabetes 2017; 66:2987-3000. [PMID: 28970281 DOI: 10.2337/db17-0655] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 09/12/2017] [Indexed: 11/13/2022]
Abstract
Recent years have seen an upsurge of interest in brown adipose tissue (BAT) to combat the epidemic of obesity and diabetes. How its development and activation are regulated at the posttranscriptional level, however, has yet to be fully understood. RNA binding proteins (RBPs) lie in the center of posttranscriptional regulation. To systemically study the role of RBPs in BAT, we profiled >400 RBPs in different adipose depots and identified Y-box binding protein 2 (Ybx2) as a novel regulator in BAT activation. Knockdown of Ybx2 blocks brown adipogenesis, whereas its overexpression promotes BAT marker expression in brown and white adipocytes. Ybx2-knockout mice could form BAT but failed to express a full thermogenic program. Integrative analysis of RNA sequencing and RNA-immunoprecipitation study revealed a set of Ybx2's mRNA targets, including Pgc1α, that were destabilized by Ybx2 depletion during cold-induced activation. Thus, Ybx2 is a novel regulator that controls BAT activation by regulating mRNA stability.
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Affiliation(s)
- Dan Xu
- School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore
| | - Shaohai Xu
- School of Chemical & Biomedical Engineering, Nanyang Technological University, Singapore
| | | | - Yen Ching Lim
- School of Laboratory Medicine and Life Science, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Sook Yoong Chia
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore
| | - Diana Teh Chee Siang
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore
| | - Juan R Alvarez-Dominguez
- Department of Stem Cell and Regenerative Biology, Harvard Stem Cell Institute, Harvard University, Cambridge, MA
| | - Peng Chen
- School of Chemical & Biomedical Engineering, Nanyang Technological University, Singapore
| | - Melvin Khee-Shing Leow
- Clinical Nutrition Research Centre, Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), Singapore
- Department of Endocrinology, Tan Tock Seng Hospital, Singapore
- Office of Clinical Sciences, Duke-NUS Medical School, Singapore
| | - Lei Sun
- Cardiovascular and Metabolic Disorders Program, Duke-NUS Medical School, Singapore
- Institute of Molecular and Cell Biology, Singapore
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Lee HC, Jung SH, Hwang HJ, Kang D, De S, Dudekula DB, Martindale JL, Park B, Park SK, Lee EK, Lee JH, Jeong S, Han K, Park HJ, Ko YG, Gorospe M, Lee JS. WIG1 is crucial for AGO2-mediated ACOT7 mRNA silencing via miRNA-dependent and -independent mechanisms. Nucleic Acids Res 2017; 45:6894-6910. [PMID: 28472401 PMCID: PMC5499809 DOI: 10.1093/nar/gkx307] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 04/28/2017] [Indexed: 12/14/2022] Open
Abstract
RNA-binding proteins (RBPs) are involved in mRNA splicing, maturation, transport, translation, storage and turnover. Here, we identified ACOT7 mRNA as a novel target of human WIG1. ACOT7 mRNA decay was triggered by the microRNA miR-9 in a WIG1-dependent manner via classic recruitment of Argonaute 2 (AGO2). Interestingly, AGO2 was also recruited to ACOT7 mRNA in a WIG1-dependent manner in the absence of miR-9, which indicates an alternative model whereby WIG1 controls AGO2-mediated gene silencing. The WIG1–AGO2 complex attenuated translation initiation via an interaction with translation initiation factor 5B (eIF5B). These results were confirmed using a WIG1 tethering system based on the MS2 bacteriophage coat protein and a reporter construct containing an MS2-binding site, and by immunoprecipitation of WIG1 and detection of WIG1-associated proteins using liquid chromatography-tandem mass spectrometry. We also identified WIG1-binding motifs using photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation analyses. Altogether, our data indicate that WIG1 governs the miRNA-dependent and the miRNA-independent recruitment of AGO2 to lower the stability of and suppress the translation of ACOT7 mRNA.
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Affiliation(s)
- Hyung Chul Lee
- Department of Molecular Medicine, Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea.,Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea
| | - Seung Hee Jung
- Department of Molecular Medicine, Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea.,Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea
| | - Hyun Jung Hwang
- Department of Molecular Medicine, Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea.,Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea
| | - Donghee Kang
- Department of Molecular Medicine, Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea.,Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea
| | - Supriyo De
- Laboratory of Genetics, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Dawood B Dudekula
- Laboratory of Genetics, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Jennifer L Martindale
- Laboratory of Genetics, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Byungkyu Park
- Department of Computer Science and Engineering, Inha University, Incheon 22212, Korea
| | - Seung Kuk Park
- Department of Molecular Biology, Dankook University, Yongin 16890, Korea
| | - Eun Kyung Lee
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Jeong-Hwa Lee
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea
| | - Sunjoo Jeong
- Department of Molecular Biology, Dankook University, Yongin 16890, Korea
| | - Kyungsook Han
- Department of Computer Science and Engineering, Inha University, Incheon 22212, Korea
| | - Heon Joo Park
- Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea.,Department of Microbiology, Inha University College of Medicine, Incheon 22212, Korea
| | - Young-Gyu Ko
- Division of Life Sciences, Korea University, Seoul 02841, Korea
| | - Myriam Gorospe
- Laboratory of Genetics, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Jae-Seon Lee
- Department of Molecular Medicine, Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea.,Medical Research Center, Inha University College of Medicine, Incheon 22212, Korea
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40
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Deschênes M, Chabot B. The emerging role of alternative splicing in senescence and aging. Aging Cell 2017; 16:918-933. [PMID: 28703423 PMCID: PMC5595669 DOI: 10.1111/acel.12646] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2017] [Indexed: 12/22/2022] Open
Abstract
Deregulation of precursor mRNA splicing is associated with many illnesses and has been linked to age-related chronic diseases. Here we review recent progress documenting how defects in the machinery that performs intron removal and controls splice site selection contribute to cellular senescence and organismal aging. We discuss the functional association linking p53, IGF-1, SIRT1, and ING-1 splice variants with senescence and aging, and review a selection of splicing defects occurring in accelerated aging (progeria), vascular aging, and Alzheimer's disease. Overall, it is becoming increasingly clear that changes in the activity of splicing factors and in the production of key splice variants can impact cellular senescence and the aging phenotype.
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Affiliation(s)
- Mathieu Deschênes
- Department of Microbiology and Infectious DiseasesFaculty of Medicine and Health SciencesUniversité de SherbrookeSherbrookeQuebecJ1E 4K8Canada
| | - Benoit Chabot
- Department of Microbiology and Infectious DiseasesFaculty of Medicine and Health SciencesUniversité de SherbrookeSherbrookeQuebecJ1E 4K8Canada
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41
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Wen H, Li P, Ma H, Zheng J, Yu Y, Lv G. High expression of Sam68 in sacral chordomas is associated with worse clinical outcomes. Onco Targets Ther 2017; 10:4691-4700. [PMID: 29026317 PMCID: PMC5626414 DOI: 10.2147/ott.s147446] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Src-associated in mitosis of 68 kDa (Sam68), also known as KHDRBS1 (KH domain-containing, RNA-binding, signal transduction-associated 1), is a member of the signal transduction and activation of RNA family. Previous studies have demonstrated that the aberrant expression of Sam68 is associated with the progression and prognosis of a variety of cancers, but little is known about its expression and role in chordomas, which are rare and aggressive bone neoplasms. In this study, we analyzed 40 tumor tissues and 20 distant normal tissues obtained from 40 patients with sacral chordoma using immunohistochemistry, and observed the expression of Sam68 was significantly upregulated in sacral chordomas compared with normal tissues (P=0.001). A positive correlation between the expression of Sam68 and the cell proliferation index Ki-67 was determined using Spearman’s rank correlation test (γ =0.599, P<0.001). In addition, high expression of Sam68 was significantly associated with surrounding muscle invasion (P<0.001). Moreover, Kaplan–Meier curves showed that patients with overexpressed Sam68 had shorter local recurrence-free survival time (P<0.001). Lastly, multivariate analysis indicated that Sam68 is an independent prognostic factor for the local recurrence-free survival of sacral chordomas (hazard ratio =5.929, 95% CI: 1.092–32.188, P=0.039). Our findings suggest the use of Sam68 as a predictor for the recurrence of sacral chordomas.
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Affiliation(s)
- Hai Wen
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Pengzhi Li
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Hong Ma
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jiaoyun Zheng
- Department of Pathology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yipin Yu
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Guohua Lv
- Department of Spine Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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42
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Li N, Hébert S, Song J, Kleinman CL, Richard S. Transcriptome profiling in preadipocytes identifies long noncoding RNAs as Sam68 targets. Oncotarget 2017; 8:81994-82005. [PMID: 29137239 PMCID: PMC5669865 DOI: 10.18632/oncotarget.17813] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 04/17/2017] [Indexed: 11/25/2022] Open
Abstract
The KH-type RNA binding protein Sam68 is required for adipogenesis. We have previously shown that Sam68-deficient mice have a lean phenotype and are protected against dietary-induced obesity due to defects in mTOR and S6K1 alternative splicing. Herein we profiled the transcriptome of Sam68 wild type and deficient 3T3-L1 mouse preadipocytes. We identified 652 protein-coding genes and 9 ncRNAs that were significantly altered with the loss of Sam68. As expected, downregulated genes were significantly associated with GO terms linked to cell migration, motility, and fat cell differentiation, while upregulated genes were mostly associated with GO terms linked to neurogenesis. Of the lncRNAs, we identified Hotair, Mir155hg, as well as two new lncRNAs (SR-lncRNA-1 and SR-lncRNA-2) that were regulated by Sam68, and contained consensus Sam68 binding sites. RNA stability assays showed that Sam68-deficiency decreased the half-life of Hotair, and increased the half-lives of Mir155hg and SR-lncRNA-2, while the stability of SR-lncRNA-1 was unaffected. Depletion of Hotair and SR-lncRNA-1 in wild type 3T3-L1 cells led to defects in adipogenesis, whereas depletion of SR-lncRNA-2 in Sam68-deficient 3T3-L1 cells partially rescued the adipogenesis defect observed in these cells. Collectively, our findings define a new role for Sam68 as a regulator of lncRNAs during adipogenic differentiation.
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Affiliation(s)
- Naomi Li
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Steven Hébert
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Human Genetics, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Jingwen Song
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
| | - Claudia L Kleinman
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Human Genetics, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Stéphane Richard
- Segal Cancer Center, Sir Mortimer B Davis Jewish General Hospital, Lady Davis Institute for Medical Research, Montréal, Québec H3T 1E2, Canada.,Department of Medicine, McGill University, Montréal, Québec H3A 1A1, Canada.,Department of Oncology, McGill University, Montréal, Québec H3A 1A1, Canada
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43
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Abstract
Alternative splicing (AS) greatly expands the coding capacities of genomes by allowing the generation of multiple mature mRNAs from a limited number of genes. Although the massive switch in AS profiles that often accompanies variations in gene expression patterns occurring during cell differentiation has been characterized for a variety of models, their causes and mechanisms remain largely unknown. Here, we integrate foundational and recent studies indicating the AS switches that govern the processes of cell fate determination. We include some distinct AS events in pluripotent cells and somatic reprogramming and discuss new progresses on alternative isoform expression in adipogenesis, myogenic differentiation and stimulation of immune cells. Finally, we cover novel insights on AS mechanisms during neuronal differentiation, paying special attention to the role of chromatin structure.
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Affiliation(s)
- Ana Fiszbein
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET) and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
| | - Alberto R Kornblihtt
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET) and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, C1428EHA Buenos Aires, Argentina
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44
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Wang J, Rajbhandari P, Damianov A, Han A, Sallam T, Waki H, Villanueva CJ, Lee SD, Nielsen R, Mandrup S, Reue K, Young SG, Whitelegge J, Saez E, Black DL, Tontonoz P. RNA-binding protein PSPC1 promotes the differentiation-dependent nuclear export of adipocyte RNAs. J Clin Invest 2017; 127:987-1004. [PMID: 28192372 DOI: 10.1172/jci89484] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 12/15/2016] [Indexed: 12/14/2022] Open
Abstract
A highly orchestrated gene expression program establishes the properties that define mature adipocytes, but the contribution of posttranscriptional factors to the adipocyte phenotype is poorly understood. Here we have shown that the RNA-binding protein PSPC1, a component of the paraspeckle complex, promotes adipogenesis in vitro and is important for mature adipocyte function in vivo. Cross-linking and immunoprecipitation followed by RNA sequencing revealed that PSPC1 binds to intronic and 3'-untranslated regions of a number of adipocyte RNAs, including the RNA encoding the transcriptional regulator EBF1. Purification of the paraspeckle complex from adipocytes further showed that PSPC1 associates with the RNA export factor DDX3X in a differentiation-dependent manner. Remarkably, PSPC1 relocates from the nucleus to the cytoplasm during differentiation, coinciding with enhanced export of adipogenic RNAs. Mice lacking PSPC1 in fat displayed reduced lipid storage and adipose tissue mass and were resistant to diet-induced obesity and insulin resistance due to a compensatory increase in energy expenditure. These findings highlight a role for PSPC1-dependent RNA maturation in the posttranscriptional control of adipose development and function.
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45
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Jia G, Jia Y, Sowers JR. Contribution of Maladaptive Adipose Tissue Expansion to Development of Cardiovascular Disease. Compr Physiol 2016; 7:253-262. [PMID: 28135006 DOI: 10.1002/cphy.c160014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The overweight and obesity epidemic has led to an increase in the metabolic syndrome and associated cardiovascular disease (CVD). These abnormalities include insulin resistance, type 2 diabetes mellitus, vascular stiffness, hypertension, stroke, and coronary heart disease. Visceral white adipocyte tissue (WAT) expansion and associated fibrosis/stiffness of WAT promote insulin resistance and CVD through increases in proinflammatory adipokines, oxidative stress, activation of renin-angiotensin-aldosterone system, dysregulation of adipocyte apoptosis and autophagy, dysfunctional immune modulation, and adverse changes in the gut microbiome. The expansion of WAT is partly determined by activation of peroxisome proliferator-activated receptor gamma and mammalian target of rapamycin/ribosomal S6 kinase signaling pathways. Further, the chronic activation of these signaling pathways may not only induce adipocyte hypertrophy and fibrosis, but also contribute to systemic inflammation, and impairment of insulin metabolic signaling in fat, liver, and skeletal muscle tissue. Therefore, the interplay of adipocyte dysfunction, maladaptive immune and inflammatory responses, and associated metabolic disorders often coexist leading to systemic low-grade inflammation and insulin resistance that are associated with increased CVD in obese individuals. © 2017 American Physiological Society. Compr Physiol 7:253-262, 2017.
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Affiliation(s)
- Guanghong Jia
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri, USA.,Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri, USA
| | - Yan Jia
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - James R Sowers
- Diabetes and Cardiovascular Research Center, University of Missouri School of Medicine, Columbia, Missouri, USA.,Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, Missouri, USA.,Dalton Cardiovascular Center, University of Missouri School of Medicine, Columbia, Missouri, USA.,Harry S. Truman Memorial Veterans Hospital, Columbia, Missouri, USA
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46
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La Rosa P, Bielli P, Compagnucci C, Cesari E, Volpe E, Farioli Vecchioli S, Sette C. Sam68 promotes self-renewal and glycolytic metabolism in mouse neural progenitor cells by modulating Aldh1a3 pre-mRNA 3'-end processing. eLife 2016; 5. [PMID: 27845622 PMCID: PMC5122457 DOI: 10.7554/elife.20750] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/14/2016] [Indexed: 12/20/2022] Open
Abstract
The balance between self-renewal and differentiation of neural progenitor cells (NPCs) dictates neurogenesis and proper brain development. We found that the RNA- binding protein Sam68 (Khdrbs1) is strongly expressed in neurogenic areas of the neocortex and supports the self-renewing potential of mouse NPCs. Knockout of Khdrbs1 constricted the pool of proliferating NPCs by accelerating their cell cycle exit and differentiation into post-mitotic neurons. Sam68 function was linked to regulation of Aldh1a3 pre-mRNA 3'-end processing. Binding of Sam68 to an intronic polyadenylation site prevents its recognition and premature transcript termination, favoring expression of a functional enzyme. The lower ALDH1A3 expression and activity in Khdrbs1-/- NPCs results in reduced glycolysis and clonogenicity, thus depleting the embryonic NPC pool and limiting cortical expansion. Our study identifies Sam68 as a key regulator of NPC self-renewal and establishes a novel link between modulation of ALDH1A3 expression and maintenance of high glycolytic metabolism in the developing cortex. DOI:http://dx.doi.org/10.7554/eLife.20750.001 Neurons develop from cells called neural progenitors. These cells can either divide to produce more progenitor cells or develop into specific types of neurons. These two activities – known as self-renewal and differentiation – must be balanced to produce the right number of specialized neurons, without depleting the pool of progenitor cells. The self-renewal and differentiation of progenitor cells is balanced by essentially regulating which genes are active, or expressed, within the cells. In the first step of gene expression, the genetic instructions are copied to form a molecule of pre-messenger RNA (or pre-mRNA for short). Each pre-mRNA molecule is then processed to produce a final product that can be translated into protein. Importantly, two copies of the same pre-mRNA may sometimes be processed in different ways, which allows multiple proteins to be produced from a single gene. RNA-binding proteins control pre-mRNA processing. The expression of one such protein, called Sam68, oscillates during the development of the nervous system, such that its expression peaks when there is intense production of new neurons and then declines. However, it was not known whether Sam68 actually helps neurons to develop. La Rosa et al. have now analysed the role of Sam68 in the developing brain of mice. The experiments confirmed that Sam68 is highly expressed in neural progenitor cells and showed that its levels dictate the cell’s fate: high expression encourages a cell to self-renew, while low expression triggers it to develop into a specialized neuron. Further investigation revealed that Sam68 works by promoting the expression of a metabolic enzyme called Aldehyde Dehydrogenase 1A3 or ALDH1A3. This enzyme promotes the release of energy from molecules of glucose via a process known as anaerobic glycolysis. La Rosa et al. found that cells that lack Sam68 make a truncated version of the pre-mRNA encoding ALDH1A3. This truncated pre-mRNA encodes a shortened version of the enzyme that is inactive. Further experiments confirmed that Sam68 normally prevents this from happening by binding to the pre-mRNA and processing it to produce the full-length, working version of the ALDH1A3 enzyme. Also, La Rosa et al. found that progenitor cells need working ALDH1A3 to keep them dividing, and to stop them from developing into specialized neurons too soon. Finally, because the processing of pre-RNA plays a major role in brain development, problems with this process often lead to intellectual disabilities and neurodegenerative diseases, such as autism spectrum disorder and amyotrophic lateral sclerosis. The next step following on from these new findings will be to investigate whether defects in Sam68 contribute to such conditions and, if so, to look for ways to counteract these defects. DOI:http://dx.doi.org/10.7554/eLife.20750.002
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Affiliation(s)
- Piergiorgio La Rosa
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Pamela Bielli
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Claudia Compagnucci
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Eleonora Cesari
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
| | - Elisabetta Volpe
- Laboratory of Neuroimmunology, Fondazione Santa Lucia, Rome, Italy
| | | | - Claudio Sette
- Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy.,Laboratory of Neuroembryology, Fondazione Santa Lucia, Rome, Italy
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47
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Sun X, Fu K, Hodgson A, Wier EM, Wen MG, Kamenyeva O, Xia X, Koo LY, Wan F. Sam68 Is Required for DNA Damage Responses via Regulating Poly(ADP-ribosyl)ation. PLoS Biol 2016; 14:e1002543. [PMID: 27635653 PMCID: PMC5026359 DOI: 10.1371/journal.pbio.1002543] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/04/2016] [Indexed: 01/08/2023] Open
Abstract
The rapid and robust synthesis of polymers of adenosine diphosphate (ADP)-ribose (PAR) chains, primarily catalyzed by poly(ADP-ribose) polymerase 1 (PARP1), is crucial for cellular responses to DNA damage. However, the precise mechanisms through which PARP1 is activated and PAR is robustly synthesized are not fully understood. Here, we identified Src-associated substrate during mitosis of 68 kDa (Sam68) as a novel signaling molecule in DNA damage responses (DDRs). In the absence of Sam68, DNA damage-triggered PAR production and PAR-dependent DNA repair signaling were dramatically diminished. With serial cellular and biochemical assays, we demonstrated that Sam68 is recruited to and significantly overlaps with PARP1 at DNA lesions and that the interaction between Sam68 and PARP1 is crucial for DNA damage-initiated and PARP1-conferred PAR production. Utilizing cell lines and knockout mice, we illustrated that Sam68-deleted cells and animals are hypersensitive to genotoxicity caused by DNA-damaging agents. Together, our findings suggest that Sam68 plays a crucial role in DDR via regulating DNA damage-initiated PAR production. The RNA-binding protein Sam68 has unexpected function in the early signaling of DNA damage, and is critical for the activation and regulation of poly(ADP-ribose) polymerase 1 in response to DNA damage. Maintaining genome integrity is crucial for all organisms, and failure to do so can lead to fatal diseases such as cancer. Exposure to challenging environments can induce DNA strand breaks or other lesions; thus, rapid and appropriate DNA damage responses (DDRs) need to be in place to detect and repair the damage. Cellular networks use a variety of signaling molecules and post-translational modifications that are crucial for the signaling of DNA breaks to repair machineries. Poly(adenosine diphosphate [ADP]-ribosyl)ation (PARylation) and activation of the enzyme poly(ADP-ribose) polymerase 1 (PARP1) is a post-translational modification that occurs within seconds upon DNA damage detection and triggers downstream DDR signaling; however, it remains obscure whether other molecules, beyond DNA strand breaks, stimulate or control PARP1 activity. We report here that a novel DDR signaling molecule, Src-associated substrate during mitosis of 68 kDa (Sam68), has a crucial function in governing the DNA damage-initiated PARP1 activation and polymers of ADP-ribose (PAR) production. We show that Sam68 is recruited to and significantly overlaps with PARP1 at DNA lesions and that the Sam68-PARP1 interaction is critical for DNA damage-initiated PARP1 activation and PAR production both in vitro and in vivo. Sam68-deleted cells and animals have a diminished PAR-dependent DNA repair signaling and are hypersensitive to genotoxicity caused by DNA-damaging agents. Hence, our data reveal an unexpected function for Sam68 in DNA damage-initiated early signaling and provide a novel mechanism on the activation and regulation of PARP1 in DDR.
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Affiliation(s)
- Xin Sun
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kai Fu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Andrea Hodgson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Eric M. Wier
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Matthew G. Wen
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Olena Kamenyeva
- Biological Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Xue Xia
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Lily Y. Koo
- Biological Imaging Facility, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Oncology, School of Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
- Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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48
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Lin JC, Chi YL, Peng HY, Lu YH. RBM4-Nova1-SRSF6 splicing cascade modulates the development of brown adipocytes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2016; 1859:1368-1379. [PMID: 27535496 DOI: 10.1016/j.bbagrm.2016.08.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/13/2016] [Accepted: 08/09/2016] [Indexed: 01/01/2023]
Abstract
Alternative splicing (AS) is a pivotal mechanism for the expansion of gene diversity, which determines the cellular fate or specification. However, the effect of AS networks on brown adipogenesis has not been comprehensively investigated. In this study, we identified the discriminative splicing profiles of RNA-binding motif protein 4a-knockout (RBM4a-/-) brown adipocytes (BAs) and compared them with those of their wild-type counterparts through deep RNA-sequencing. Among these candidates, RBM4a ablation enhanced the relative level of exon 4-excluded neuro-oncological ventral antigen 1 (Nova1-4) transcripts, which were predominantly generated in embryonic BAs. By contrast, most of the Nova1 transcripts were exon 4-included (Nova1+4) in mature BAs. The Nova1 isoforms exhibited differential effects on repressing the development of BAs. Moreover, overexpression of Nova1 proteins reduced the serine/arginine splicing factor 6 (SRSF6) level by enhancing the generation of intron 2-included (SRSF6+intron 2) transcripts, which are a putative candidate of the AS-coupled nonsense-mediated decay mechanism. Furthermore, we observed the positive effect of SRSF6 on BA development. These results highlight the hierarchical role of RBM4a in an AS cascade that manipulates brown adipogenesis.
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Affiliation(s)
- Jung-Chun Lin
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
| | - Yi-Lin Chi
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Hui-Yu Peng
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Yi-Han Lu
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
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49
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Fu K, Sun X, Wier EM, Hodgson A, Liu Y, Sears CL, Wan F. Sam68/KHDRBS1 is critical for colon tumorigenesis by regulating genotoxic stress-induced NF-κB activation. eLife 2016; 5. [PMID: 27458801 PMCID: PMC4959885 DOI: 10.7554/elife.15018] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 06/29/2016] [Indexed: 12/19/2022] Open
Abstract
Nuclear factor kappa B (NF-κB)-mediated transcription is an important mediator for cellular responses to DNA damage. Genotoxic agents trigger a 'nuclear-to-cytoplasmic' NF-κB activation signaling pathway; however, the early nuclear signaling cascade linking DNA damage and NF-κB activation is poorly understood. Here we report that Src-associated-substrate-during-mitosis-of-68kDa/KH domain containing, RNA binding, signal transduction associated 1 (Sam68/KHDRBS1) is a key NF-κB regulator in genotoxic stress-initiated signaling pathway. Sam68 deficiency abolishes DNA damage-stimulated polymers of ADP-ribose (PAR) production and the PAR-dependent NF-κB transactivation of anti-apoptotic genes. Sam68 deleted cells are hypersensitive to genotoxicity caused by DNA damaging agents. Upregulated Sam68 coincides with elevated PAR production and NF-κB-mediated anti-apoptotic transcription in human and mouse colon cancer. Knockdown of Sam68 sensitizes human colon cancer cells to genotoxic stress-induced apoptosis and genetic deletion of Sam68 dampens colon tumor burden in mice. Together our data reveal a novel function of Sam68 in the genotoxic stress-initiated nuclear signaling, which is crucial for colon tumorigenesis. DOI:http://dx.doi.org/10.7554/eLife.15018.001 Cells use signaling pathways to detect and respond to harmful conditions by switching on genes that keep the cell healthy. One important pathway is the nuclear factor kappa B (NF-κB) signaling pathway, which is activated by many stimuli. These stimuli may come from infections from outside the cell or may originate inside the cell, as seen for DNA damage caused by irradiation, chemicals or rapid DNA replication in cancer cells. Most of a cell’s DNA is located in the cell nucleus. However, NF-κB proteins are normally located outside the nucleus, in the cell’s cytoplasm. Damage to DNA triggers a signal from the nucleus to the cytoplasm. This signal activates the NF-κB proteins, which move into the nucleus and turn on genes that help the cell to recover from the damage. These genes include those that prevent the cell from self-destructing. In one step of the NF-κB activation process, chain-like molecules called polymers are made from a compound called poly(ADP-ribose), or PAR for short. However, few other details are known about how the damaged DNA in the nucleus signals to the cytoplasm. A protein called Sam68, which is found in the cell nucleus, has been linked to DNA damage signaling. Fu, Sun et al. now present evidence that suggests that if mouse cells lack Sam68, they do not produce PAR polymers in response to DNA damage. In addition, these cells could not trigger the PAR-dependent signaling cascade that is essential for activating NF-κB and for turning on the protective genes. Consequently, cells that lacked Sam68 were extremely sensitive to agents that cause DNA damage, such as chemicals and irradiation. The NF-κB pathway is regulated incorrectly in some cancers, but is also activated by DNA damage caused by cancer treatments. Therefore, Fu, Sun et al. also explored the role of Sam68 in cancer. Reducing the levels of Sam68 made human colon cancer cells more likely to self-destruct when they were exposed to DNA-damaging agents. Furthermore, removing Sam68 from mice that spontaneously grow colon cancer caused their tumors to develop more slowly than mice that retained Sam68 in their cells. Overall, the findings presented by Fu, Sun et al. suggest that Sam68 regulates the signal from the nucleus to the cytoplasm that activates NF-κB proteins in response to DNA damage. Sam68 also appears to be important for helping colon cancer cells grow and survive. Future challenges will be to understand how Sam68 regulates the production of the PAR polymer in this response and to explore whether Sam68 can be targeted for treating cancer. DOI:http://dx.doi.org/10.7554/eLife.15018.002
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Affiliation(s)
- Kai Fu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Xin Sun
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Eric M Wier
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Andrea Hodgson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States.,W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, John Hopkins University, Baltimore, United States
| | - Yue Liu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States
| | - Cynthia L Sears
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, John Hopkins University, Baltimore, United States.,Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, United States.,Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Medical Institutions, Baltimore, United States
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, United States.,Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins Medical Institutions, Baltimore, United States
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50
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Wang Q, Li Y, Cheng J, Chen L, Xu H, Li Q, Pang T. Sam68 affects cell proliferation and apoptosis of human adult T-acute lymphoblastic leukemia cells via AKT/mTOR signal pathway. Leuk Res 2016; 46:1-9. [DOI: 10.1016/j.leukres.2016.04.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Revised: 04/07/2016] [Accepted: 04/11/2016] [Indexed: 01/02/2023]
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