1
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Hong Y, Kim I, Moon H, Lee J, Lertpatipanpong P, Ryu CH, Jung YS, Seok J, Kim Y, Ryu J, Baek SJ. Novel thrombospondin-1 transcript exhibits distinctive expression and activity in thyroid tumorigenesis. Oncogene 2023:10.1038/s41388-023-02692-9. [PMID: 37055552 DOI: 10.1038/s41388-023-02692-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 03/29/2023] [Accepted: 03/31/2023] [Indexed: 04/15/2023]
Abstract
Thrombospondin 1 (TSP1) is known for its cell-specific functions in cancer progression, such as proliferation and migration. It contains 22 exons that may potentially produce several different transcripts. Here, we identified TSP1V as a novel TSP1-splicing variant produced by intron retention (IR) in human thyroid cancer cells and tissues. We observed that TSP1V functionally inhibited tumorigenesis contrary to TSP1 wild-type, as identified in vivo and in vitro. These activities of TSP1V are caused by inhibiting phospho-Smad and phospho-focal adhesion kinase. Reverse transcription polymerase chain reaction and minigene experiments revealed that some phytochemicals/non-steroidal anti-inflammatory drugs enhanced IR. We further found that RNA-binding motif protein 5 (RBM5) suppressed IR induced by sulindac sulfide treatment. Additionally, sulindac sulfide reduced phospho-RBM5 levels in a time-dependent manner. Furthermore, trans-chalcone demethylated TSP1V, thereby preventing methyl-CpG-binding protein 2 binding to TSP1V gene. In addition, TSP1V levels were significantly lower in patients with differentiated thyroid carcinoma than in those with benign thyroid nodule, indicating its potential application as a diagnostic biomarker in tumor progression.
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Affiliation(s)
- Yukyung Hong
- College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Ilju Kim
- College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Hyunjin Moon
- College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Jaehak Lee
- College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Pattawika Lertpatipanpong
- College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea
| | - Chang Hwan Ryu
- Department of Otolaryngology-Head and Neck Surgery, Center for Thyroid Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea
| | - Yuh-Seog Jung
- Department of Otolaryngology-Head and Neck Surgery, Center for Thyroid Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea
| | - Jungirl Seok
- Department of Otolaryngology-Head and Neck Surgery, Center for Thyroid Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea
| | - Yonghwan Kim
- Department of Biological Sciences, Research Institute of Women's Health and Digital Humanity Center, Sookmyung Women's University, Seoul, 04310, Korea
| | - Junsun Ryu
- Department of Otolaryngology-Head and Neck Surgery, Center for Thyroid Cancer, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
| | - Seung Joon Baek
- College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, Korea.
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2
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Song M, Pang L, Zhang M, Qu Y, Laster KV, Dong Z. Cdc2-like kinases: structure, biological function, and therapeutic targets for diseases. Signal Transduct Target Ther 2023; 8:148. [PMID: 37029108 PMCID: PMC10082069 DOI: 10.1038/s41392-023-01409-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 03/15/2023] [Accepted: 03/20/2023] [Indexed: 04/09/2023] Open
Abstract
The CLKs (Cdc2-like kinases) belong to the dual-specificity protein kinase family and play crucial roles in regulating transcript splicing via the phosphorylation of SR proteins (SRSF1-12), catalyzing spliceosome molecular machinery, and modulating the activities or expression of non-splicing proteins. The dysregulation of these processes is linked with various diseases, including neurodegenerative diseases, Duchenne muscular dystrophy, inflammatory diseases, viral replication, and cancer. Thus, CLKs have been considered as potential therapeutic targets, and significant efforts have been exerted to discover potent CLKs inhibitors. In particular, clinical trials aiming to assess the activities of the small molecules Lorecivivint on knee Osteoarthritis patients, and Cirtuvivint and Silmitasertib in different advanced tumors have been investigated for therapeutic usage. In this review, we comprehensively documented the structure and biological functions of CLKs in various human diseases and summarized the significance of related inhibitors in therapeutics. Our discussion highlights the most recent CLKs research, paving the way for the clinical treatment of various human diseases.
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Affiliation(s)
- Mengqiu Song
- Department of Pathophysiology, School of Basic Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China
- China-US (Henan) Hormel Cancer Institute, No.127, Dongming Road, Jinshui District, Zhengzhou, Henan, 450008, China
- State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, Henan, China
| | - Luping Pang
- State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, Henan, China
- Academy of Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China
- Research Center of Basic Medicine, Academy of Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Mengmeng Zhang
- Department of Pathophysiology, School of Basic Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China
- Academy of Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Yingzi Qu
- Department of Pathophysiology, School of Basic Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China
- Academy of Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China
| | - Kyle Vaughn Laster
- China-US (Henan) Hormel Cancer Institute, No.127, Dongming Road, Jinshui District, Zhengzhou, Henan, 450008, China
| | - Zigang Dong
- Department of Pathophysiology, School of Basic Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China.
- China-US (Henan) Hormel Cancer Institute, No.127, Dongming Road, Jinshui District, Zhengzhou, Henan, 450008, China.
- State Key Laboratory of Esophageal Cancer Prevention and Treatment, Zhengzhou University, Zhengzhou, Henan, China.
- Academy of Medical Sciences, College of Medicine, Zhengzhou University, Zhengzhou, Henan, 450001, China.
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3
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De Silva NIU, Fargason T, Zhang Z, Wang T, Zhang J. Inter-domain Flexibility of Human Ser/Arg-Rich Splicing Factor 1 Allows Variable Spacer Length in Cognate RNA’s Bipartite Motifs. Biochemistry 2022; 61:2922-2932. [DOI: 10.1021/acs.biochem.2c00565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Naiduwadura Ivon Upekala De Silva
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Talia Fargason
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Zihan Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Ting Wang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
| | - Jun Zhang
- Department of Chemistry, College of Arts and Sciences, University of Alabama at Birmingham, CH266, 901 14th Street South, Birmingham, Alabama35294-1240, United States
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4
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Sun M, Jin Y, Zhang Y, Gregorich ZR, Ren J, Ge Y, Guo W. SR Protein Kinases Regulate the Splicing of Cardiomyopathy-Relevant Genes via Phosphorylation of the RSRSP Stretch in RBM20. Genes (Basel) 2022; 13:1526. [PMID: 36140694 PMCID: PMC9498672 DOI: 10.3390/genes13091526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 08/22/2022] [Accepted: 08/23/2022] [Indexed: 11/16/2022] Open
Abstract
(1) Background: RNA binding motif 20 (RBM20) regulates mRNA splicing specifically in muscle tissues. Missense mutations in the arginine/serine (RS) domain of RBM20 lead to abnormal gene splicing and have been linked to severe dilated cardiomyopathy (DCM) in human patients and animal models. Interestingly, many of the reported DCM-linked missense mutations in RBM20 are in a highly conserved RSRSP stretch within the RS domain. Recently, it was found that the two Ser residues within this stretch are constitutively phosphorylated, yet the identity of the kinase(s) responsible for phosphorylating these residues, as well as the function of RSRSP phosphorylation, remains unknown. (2) Methods: The ability of three known SR protein kinases (SRPK1, CLK1, and AKT2) to phosphorylate the RBM20 RSRSP stretch and regulate target gene splicing was evaluated by using both in vitro and in vivo approaches. (3) Results: We found that all three kinases phosphorylated S638 and S640 in the RSRSP stretch and regulated RBM20 target gene splicing. While SRPK1 and CLK1 were both capable of directly phosphorylating the RS domain in RBM20, whether AKT2-mediated control of the RS domain phosphorylation is direct or indirect could not be determined. (4) Conclusions: Our results indicate that SR protein kinases regulate the splicing of a cardiomyopathy-relevant gene by modulating phosphorylation of the RSRSP stretch in RBM20. These findings suggest that SR protein kinases may be potential targets for the treatment of RBM20 cardiomyopathy.
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Affiliation(s)
- Mingming Sun
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
| | - Yutong Jin
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Yanghai Zhang
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Zachery R Gregorich
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jun Ren
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital Fudan University, Shanghai 200032, China
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Cell and Regenerative Biology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53706, USA
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Wei Guo
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
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5
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AKT1 Transcriptomic Landscape in Breast Cancer Cells. Cells 2022; 11:cells11152290. [PMID: 35892586 PMCID: PMC9332453 DOI: 10.3390/cells11152290] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 07/05/2022] [Accepted: 07/11/2022] [Indexed: 12/10/2022] Open
Abstract
Overexpression and hyperactivation of the serine/threonine protein kinase B (AKT) pathway is one of the most common cellular events in breast cancer progression. However, the nature of AKT1-specific genome-wide transcriptomic alterations in breast cancer cells and breast cancer remains unknown to this point. Here, we delineate the impact of selective AKT1 knock down using gene-specific siRNAs or inhibiting the AKT activity with a pan-AKT inhibitor VIII on the nature of transcriptomic changes in breast cancer cells using the genome-wide RNA-sequencing analysis. We found that changes in the cellular levels of AKT1 lead to changes in the levels of a set of differentially expressed genes and, in turn, imply resulting AKT1 cellular functions. In addition to an expected positive relationship between the status of AKT1 and co-expressed cellular genes, our study unexpectedly discovered an inherent role of AKT1 in inhibiting the expression of a subset of genes in both unstimulated and growth factor stimulated breast cancer cells. We found that depletion of AKT1 leads to upregulation of a subset of genes—many of which are also found to be downregulated in breast tumors with elevated high AKT1 as well as upregulated in breast tumors with no detectable AKT expression. Representative experimental validation studies in two breast cancer cell lines showed a reasonable concurrence between the expression data from the RNA-sequencing and qRT-PCR or data from ex vivo inhibition of AKT1 activity in cancer patient-derived cells. In brief, findings presented here provide a resource for further understanding of AKT1-dependent modulation of gene expression in breast cancer cells and broaden the scope and significance of AKT1 targets and their functions.
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6
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Integrated lncRNA function upon genomic and epigenomic regulation. Mol Cell 2022; 82:2252-2266. [PMID: 35714586 DOI: 10.1016/j.molcel.2022.05.027] [Citation(s) in RCA: 136] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 05/09/2022] [Accepted: 05/23/2022] [Indexed: 12/20/2022]
Abstract
Although some long noncoding (lnc)RNAs are known since the 1950s, the past 25 years have uncovered myriad lncRNAs with diverse sequences, structures, and functions. The advent of high-throughput and sensitive technologies has further uncovered the vast heterogeneity of lncRNA-interacting molecules and patterns of expressed lncRNAs. We propose a unifying functional theme for the expansive family of lncRNAs. At an elementary level, the genomic program of gene expression is elicited via canonical transcription and post-transcriptional mRNA assembly, turnover, and translation. Building upon this regulation, an epigenomic program refines the basic genomic control by modifying chromatin architecture as well as DNA and RNA chemistry. Superimposed over the genomic and epigenomic programs, lncRNAs create an additional regulatory dimension: by interacting with the proteins and nucleic acids that regulate gene expression in the nucleus and cytoplasm, lncRNAs help establish robust, nimble, and specific transcriptional and post-transcriptional control. We describe our present understanding of lncRNA-coordinated control of protein programs and cell fate and discuss challenges and opportunities as we embark on the next 25 years of lncRNA discovery.
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7
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Ladewig E, Michelini F, Jhaveri K, Castel P, Carmona J, Fairchild L, Zuniga AG, Arruabarrena-Aristorena A, Cocco E, Blawski R, Kittane S, Zhang Y, Sallaku M, Baldino L, Hristidis V, Chandarlapaty S, Abdel-Wahab O, Leslie C, Scaltriti M, Toska E. The oncogenic PI3K-induced transcriptomic landscape reveals key functions in splicing and gene expression regulation. Cancer Res 2022; 82:2269-2280. [PMID: 35442400 DOI: 10.1158/0008-5472.can-22-0446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/25/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022]
Abstract
The PI3K pathway regulates proliferation, survival, and metabolism and is frequently activated across human cancers. A comprehensive elucidation of how this signaling pathway controls transcriptional and co-transcriptional processes could provide new insights into the key functions of PI3K signaling in cancer. Here, we undertook a transcriptomic approach to investigate genome-wide gene expression and transcription factor (TF) activity changes, as well as splicing and isoform usage dynamics, downstream of PI3K. These analyses uncovered widespread alternatively spliced (AS) isoforms linked to proliferation, metabolism, and splicing in PIK3CA mutant cells, which were reversed by inhibition of PI3Kα. Analysis of paired tumor biopsies from PIK3CA-mutated breast cancer patients undergoing treatment with PI3Kα inhibitors identified widespread splicing alterations that affect specific isoforms in common with the preclinical models, and these alterations, namely PTK2/FRNK and AFMID isoforms, were validated as functional drivers of cancer cell growth or migration. Mechanistically, isoform-specific splicing factors mediated PI3K-dependent RNA splicing. Treatment with splicing inhibitors rendered breast cancer cells more sensitive to the PI3Kα inhibitor alpelisib, resulting in greater growth inhibition than alpelisib alone. This study provides the first comprehensive analysis of widespread splicing alterations driven by oncogenic PI3K in breast cancer. The atlas of PI3K-mediated splicing programs establishes a key role for the PI3K pathway in regulating splicing, opening new avenues for exploiting PI3K signaling as a therapeutic vulnerability in breast cancer.
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Affiliation(s)
- Erik Ladewig
- Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | | | - Komal Jhaveri
- Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, NY, United States
| | - Pau Castel
- NYU Langone, New York, NY, United States
| | - Javier Carmona
- Vall d'Hebron Barcelona Hospital Campus, Barcelona, Spain
| | - Lauren Fairchild
- Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | - Adler G Zuniga
- Johns Hopkins University School of Medicine, United States
| | | | | | - Ryan Blawski
- Johns Hopkins University School of Medicine, United States
| | - Srushti Kittane
- Johns Hopkins University Bloomberg School of Public Health, Baltimore, United States
| | - Yuhan Zhang
- Johns Hopkins University, Baltimore, United States
| | | | - Laura Baldino
- Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | | | | | - Omar Abdel-Wahab
- Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | - Christina Leslie
- Memorial Sloan Kettering Cancer Center, New York, NY, United States
| | | | - Eneda Toska
- Johns Hopkins University, Baltimore, United States
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8
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Ruta V, Pagliarini V, Sette C. Coordination of RNA Processing Regulation by Signal Transduction Pathways. Biomolecules 2021; 11:biom11101475. [PMID: 34680108 PMCID: PMC8533259 DOI: 10.3390/biom11101475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/01/2021] [Accepted: 10/05/2021] [Indexed: 02/06/2023] Open
Abstract
Signal transduction pathways transmit the information received from external and internal cues and generate a response that allows the cell to adapt to changes in the surrounding environment. Signaling pathways trigger rapid responses by changing the activity or localization of existing molecules, as well as long-term responses that require the activation of gene expression programs. All steps involved in the regulation of gene expression, from transcription to processing and utilization of new transcripts, are modulated by multiple signal transduction pathways. This review provides a broad overview of the post-translational regulation of factors involved in RNA processing events by signal transduction pathways, with particular focus on the regulation of pre-mRNA splicing, cleavage and polyadenylation. The effects of several post-translational modifications (i.e., sumoylation, ubiquitination, methylation, acetylation and phosphorylation) on the expression, subcellular localization, stability and affinity for RNA and protein partners of many RNA-binding proteins are highlighted. Moreover, examples of how some of the most common signal transduction pathways can modulate biological processes through changes in RNA processing regulation are illustrated. Lastly, we discuss challenges and opportunities of therapeutic approaches that correct RNA processing defects and target signaling molecules.
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Affiliation(s)
- Veronica Ruta
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (V.R.); (V.P.)
- Organoids Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy
| | - Vittoria Pagliarini
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (V.R.); (V.P.)
- Organoids Facility, IRCCS Fondazione Policlinico Universitario Agostino Gemelli, 00168 Rome, Italy
| | - Claudio Sette
- Department of Neuroscience, Section of Human Anatomy, Catholic University of the Sacred Heart, 00168 Rome, Italy; (V.R.); (V.P.)
- Laboratory of Neuroembryology, IRCCS Fondazione Santa Lucia, 00143 Rome, Italy
- Correspondence:
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9
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Wang Z, Gao X, Li Q, Zhu H, Zhao X, Garcia-Barrio M, Zhang J, Guo Y, Chen YE, Zeng R, Wu JR, Chang L. Inhibition of a Novel CLK1-THRAP3-PPARγ Axis Improves Insulin Sensitivity. Front Physiol 2021; 12:699578. [PMID: 34526909 PMCID: PMC8435799 DOI: 10.3389/fphys.2021.699578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 08/09/2021] [Indexed: 11/13/2022] Open
Abstract
Increasing energy expenditure by promoting "browning" in adipose tissues is a promising strategy to prevent obesity and associated diabetes. To uncover potential targets of cold exposure, which induces energy expenditure, we performed phosphoproteomics profiling in brown adipose tissue of mice housed in mild cold environment at 16°C. We identified CDC2-like kinase 1 (CLK1) as one of the kinases that were significantly downregulated by mild cold exposure. In addition, genetic knockout of CLK1 or chemical inhibition in mice ameliorated diet-induced obesity and insulin resistance at 22°C. Through proteomics, we uncovered thyroid hormone receptor-associated protein 3 (THRAP3) as an interacting partner of CLK1, further confirmed by co-immunoprecipitation assays. We further demonstrated that CLK1 phosphorylates THRAP3 at Ser243, which is required for its regulatory interaction with phosphorylated peroxisome proliferator-activated receptor gamma (PPARγ), resulting in impaired adipose tissue browning and insulin sensitivity. These data suggest that CLK1 plays a critical role in controlling energy expenditure through the CLK1-THRAP3-PPARγ axis.
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Affiliation(s)
- Zhenguo Wang
- Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, Ann Arbor, MI, United States
- CAS Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Hangzhou, China
| | - Xiaojing Gao
- CAS Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Hangzhou, China
- Key Laboratory of Systems Biology, CAS Center for Excellence in Molecular Cell Science, Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Qingrun Li
- CAS Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Hangzhou, China
| | - Hongwen Zhu
- CAS Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Hangzhou, China
| | - Xiangjie Zhao
- Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, Ann Arbor, MI, United States
| | - Minerva Garcia-Barrio
- Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, Ann Arbor, MI, United States
| | - Jifeng Zhang
- Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, Ann Arbor, MI, United States
| | - Yanhong Guo
- Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, Ann Arbor, MI, United States
| | - Y. Eugene Chen
- Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, Ann Arbor, MI, United States
| | - Rong Zeng
- CAS Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Hangzhou, China
- School of Life Sciences and Technology, Shanghai Tech University, Shanghai, China
| | - Jia-Rui Wu
- CAS Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Hangzhou, China
- School of Life Sciences and Technology, Shanghai Tech University, Shanghai, China
| | - Lin Chang
- Department of Internal Medicine, Cardiovascular Center, University of Michigan Medical Center, Ann Arbor, MI, United States
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10
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Cisneros-Villanueva M, Hidalgo-Pérez L, Cedro-Tanda A, Peña-Luna M, Mancera-Rodríguez MA, Hurtado-Cordova E, Rivera-Salgado I, Martínez-Aguirre A, Jiménez-Morales S, Alfaro-Ruiz LA, Arellano-Llamas R, Tenorio-Torres A, Domínguez-Reyes C, Villegas-Carlos F, Ríos-Romero M, Hidalgo-Miranda A. LINC00460 Is a Dual Biomarker That Acts as a Predictor for Increased Prognosis in Basal-Like Breast Cancer and Potentially Regulates Immunogenic and Differentiation-Related Genes. Front Oncol 2021; 11:628027. [PMID: 33912452 PMCID: PMC8074675 DOI: 10.3389/fonc.2021.628027] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 03/10/2021] [Indexed: 12/23/2022] Open
Abstract
Breast cancer (BRCA) is a serious public health problem, as it is the most frequent malignant tumor in women worldwide. BRCA is a molecularly heterogeneous disease, particularly at gene expression (mRNAs) level. Recent evidence shows that coding RNAs represent only 34% of the total transcriptome in a human cell. The rest of the 66% of RNAs are non−coding, so we might be missing relevant biological, clinical or regulatory information. In this report, we identified two novel tumor types from TCGA with LINC00460 deregulation. We used survival analysis to demonstrate that LINC00460 expression is a marker for poor overall (OS), relapse-free (RFS) and distant metastasis-free survival (DMFS) in basal-like BRCA patients. LINC00460 expression is a potential marker for aggressive phenotypes in distinct tumors, including HPV-negative HNSC, stage IV KIRC, locally advanced lung cancer and basal-like BRCA. We show that the LINC00460 prognostic expression effect is tissue-specific, since its upregulation can predict poor OS in some tumors, but also predicts an improved clinical course in BRCA patients. We found that the LINC00460 expression is significantly enriched in the Basal-like 2 (BL2) TNBC subtype and potentially regulates the WNT differentiation pathway. LINC00460 can also modulate a plethora of immunogenic related genes in BRCA, such as SFRP5, FOSL1, IFNK, CSF2, DUSP7 and IL1A and interacts with miR-103-a-1, in-silico, which, in turn, can no longer target WNT7A. Finally, LINC00460:WNT7A ratio constitutes a composite marker for decreased OS and DMFS in Basal-like BRCA, and can predict anthracycline therapy response in ER-BRCA patients. This evidence confirms that LINC00460 is a master regulator in BRCA molecular circuits and influences clinical outcome.
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Affiliation(s)
- Mireya Cisneros-Villanueva
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México.,Laboratorio de Epigenética del Cáncer, Facultad de Ciencias Químico Biológicas, Universidad Autónoma de Guerrero, Chilpancingo de los Bravo, Mexico
| | - Lizbett Hidalgo-Pérez
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México.,Programa de Doctorado en Ciencias Biomédicas, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Alberto Cedro-Tanda
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México
| | - Mónica Peña-Luna
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México
| | | | - Eduardo Hurtado-Cordova
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México
| | - Irene Rivera-Salgado
- Departamento de Anatomía Patológica, Hospital Central Sur de Alta Especialidad, Petróleos Mexicanos, Ciudad de México, México
| | - Alejandro Martínez-Aguirre
- Departamento de Anatomía Patológica, Hospital Central Sur de Alta Especialidad, Petróleos Mexicanos, Ciudad de México, México
| | - Silvia Jiménez-Morales
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México
| | - Luis Alberto Alfaro-Ruiz
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México
| | - Rocío Arellano-Llamas
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México
| | | | | | | | - Magdalena Ríos-Romero
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México.,Posgrado en Ciencias Biológicas, Unidad de Posgrado, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, México
| | - Alfredo Hidalgo-Miranda
- Laboratorio de Genómica del Cáncer, Instituto Nacional de Medicina Genómica (INMEGEN), Ciudad de México, México
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11
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Pisignano G, Ladomery M. Epigenetic Regulation of Alternative Splicing: How LncRNAs Tailor the Message. Noncoding RNA 2021; 7:ncrna7010021. [PMID: 33799493 PMCID: PMC8005942 DOI: 10.3390/ncrna7010021] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/05/2021] [Accepted: 02/22/2021] [Indexed: 12/23/2022] Open
Abstract
Alternative splicing is a highly fine-tuned regulated process and one of the main drivers of proteomic diversity across eukaryotes. The vast majority of human multi-exon genes is alternatively spliced in a cell type- and tissue-specific manner, and defects in alternative splicing can dramatically alter RNA and protein functions and lead to disease. The eukaryotic genome is also intensively transcribed into long and short non-coding RNAs which account for up to 90% of the entire transcriptome. Over the years, lncRNAs have received considerable attention as important players in the regulation of cellular processes including alternative splicing. In this review, we focus on recent discoveries that show how lncRNAs contribute significantly to the regulation of alternative splicing and explore how they are able to shape the expression of a diverse set of splice isoforms through several mechanisms. With the increasing number of lncRNAs being discovered and characterized, the contribution of lncRNAs to the regulation of alternative splicing is likely to grow significantly.
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Affiliation(s)
- Giuseppina Pisignano
- Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
- Correspondence: (G.P.); (M.L.)
| | - Michael Ladomery
- Faculty of Health and Applied Sciences, University of the West of England, Coldharbour Lane, Frenchay, Bristol BS16 1QY, UK
- Correspondence: (G.P.); (M.L.)
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12
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Hull R, Mbita Z, Dlamini Z. Long non-coding RNAs (LncRNAs), viral oncogenomics, and aberrant splicing events: therapeutics implications. Am J Cancer Res 2021; 11:866-883. [PMID: 33791160 PMCID: PMC7994164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023] Open
Abstract
It has been estimated that worldwide up to 10% of all human cancers are the result of viral infection, with 7.2% of all cancers in the developed world have a viral aetiology. In contrast, 22.9% of infections in the developing world are the result of viral infections. This number increases to 30% in Sub-Saharan Africa. The ability of viral infections to induce the transformation of normal cells into cancerous cells is well documented. These viruses are mainly Hepatitis B and C viruses, Epstein Barr virus, Human papillomavirus and Human Cytomegalovirus. They can induce the transformation of normal cells into cancer cells and this may be the underlying cause of carcinogenesis in many different types of cancer. These include liver cancer, lymphoma, nasopharyngeal cancer, cervical cancer, gastric cancer and even glioblastoma. Long non-coding RNAs (LncRNAs) can function by regulating the expression of their target genes by controlling the stability of the target mRNAs or by blocking translation of the target mRNA. They can control transcription by regulating the recruitment of transcription factors or chromatin modification complexes. Finally, lncRNAs can control the phosphorylation, acetylation, and ubiquitination of proteins at the post-translation level. Thus, altering protein localisation, function, folding, stability and ultimately expression. In addition to these functions, lncRNA also regulate alternate pre-mRNA splicing in ways that contribute to the formation of tumours. This mainly involves the interaction of lncRNAs with splicing factors, which alters their activity and function. The ability of lncRNAs to regulate the stability, expression and function of tumour suppressor proteins is important in the development and progression of cancers. LncRNAs also regulate viral replication and latency, leading to carcinogenesis. These factors all make lncRNAs ideal targets for the development of biomarker arrays that can be based on secreted lncRNAs leading to the development of affordable non-invasive biomarker tests for the stage specific diagnosis of tumours. These lncRNAs can also serve as targets for the development of new anticancer drug treatments.
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Affiliation(s)
- Rodney Hull
- SA-MRC/UP Precision Prevention & Novel Drug Targets for HIV-Associated Cancers Extramural Unit, Pan African Cancer Research Institute, University of Pretoria Hatfield0028, South Africa
| | - Zukile Mbita
- Department of Biochemistry, Microbiology and Biochemistry, University of LimpopoSovenga 0727, South Africa
| | - Zodwa Dlamini
- SA-MRC/UP Precision Prevention & Novel Drug Targets for HIV-Associated Cancers Extramural Unit, Pan African Cancer Research Institute, University of Pretoria Hatfield0028, South Africa
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13
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Fonouni-Farde C, Ariel F, Crespi M. Plant Long Noncoding RNAs: New Players in the Field of Post-Transcriptional Regulations. Noncoding RNA 2021; 7:12. [PMID: 33671131 PMCID: PMC8005961 DOI: 10.3390/ncrna7010012] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 02/12/2021] [Accepted: 02/14/2021] [Indexed: 02/08/2023] Open
Abstract
The first reference to the "C-value paradox" reported an apparent imbalance between organismal genome size and morphological complexity. Since then, next-generation sequencing has revolutionized genomic research and revealed that eukaryotic transcriptomes contain a large fraction of non-protein-coding components. Eukaryotic genomes are pervasively transcribed and noncoding regions give rise to a plethora of noncoding RNAs with undeniable biological functions. Among them, long noncoding RNAs (lncRNAs) seem to represent a new layer of gene expression regulation, participating in a wide range of molecular mechanisms at the transcriptional and post-transcriptional levels. In addition to their role in epigenetic regulation, plant lncRNAs have been associated with the degradation of complementary RNAs, the regulation of alternative splicing, protein sub-cellular localization, the promotion of translation and protein post-translational modifications. In this review, we report and integrate numerous and complex mechanisms through which long noncoding transcripts regulate post-transcriptional gene expression in plants.
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Affiliation(s)
- Camille Fonouni-Farde
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), Bat 630, 91192 Gif sur Yvette, France;
- Université de Paris, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), Bat 630, 91192 Gif sur Yvette, France
| | - Federico Ariel
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina;
| | - Martin Crespi
- Université Paris-Saclay, CNRS, INRAE, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), Bat 630, 91192 Gif sur Yvette, France;
- Université de Paris, CNRS, INRAE, Institute of Plant Sciences Paris-Saclay (IPS2), Bat 630, 91192 Gif sur Yvette, France
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14
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Batista TM, Jayavelu AK, Wewer Albrechtsen NJ, Iovino S, Lebastchi J, Pan H, Dreyfuss JM, Krook A, Zierath JR, Mann M, Kahn CR. A Cell-Autonomous Signature of Dysregulated Protein Phosphorylation Underlies Muscle Insulin Resistance in Type 2 Diabetes. Cell Metab 2020; 32:844-859.e5. [PMID: 32888406 PMCID: PMC7875546 DOI: 10.1016/j.cmet.2020.08.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/26/2020] [Accepted: 08/11/2020] [Indexed: 02/06/2023]
Abstract
Skeletal muscle insulin resistance is the earliest defect in type 2 diabetes (T2D), preceding and predicting disease development. To what extent this reflects a primary defect or is secondary to tissue cross talk due to changes in hormones or circulating metabolites is unknown. To address this question, we have developed an in vitro disease-in-a-dish model using iPS cells from T2D patients differentiated into myoblasts (iMyos). We find that T2D iMyos in culture exhibit multiple defects mirroring human disease, including an altered insulin signaling, decreased insulin-stimulated glucose uptake, and reduced mitochondrial oxidation. More strikingly, global phosphoproteomic analysis reveals a multidimensional network of signaling defects in T2D iMyos going beyond the canonical insulin-signaling cascade, including proteins involved in regulation of Rho GTPases, mRNA splicing and/or processing, vesicular trafficking, gene transcription, and chromatin remodeling. These cell-autonomous defects and the dysregulated network of protein phosphorylation reveal a new dimension in the cellular mechanisms underlying the fundamental defects in T2D.
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Affiliation(s)
- Thiago M Batista
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Ashok Kumar Jayavelu
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Nicolai J Wewer Albrechtsen
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark; Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen 2100, Denmark
| | - Salvatore Iovino
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jasmin Lebastchi
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Hui Pan
- Bioinformatics and Biostatistics Core, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Jonathan M Dreyfuss
- Bioinformatics and Biostatistics Core, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA
| | - Anna Krook
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm 171 77, Sweden
| | - Juleen R Zierath
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark; Section of Integrative Physiology, Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm 171 76, Sweden
| | - Matthias Mann
- Department of Proteomics and Signal Transduction, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany; Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark
| | - C Ronald Kahn
- Section of Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA 02215, USA.
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15
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Cdc-Like Kinases (CLKs): Biology, Chemical Probes, and Therapeutic Potential. Int J Mol Sci 2020; 21:ijms21207549. [PMID: 33066143 PMCID: PMC7593917 DOI: 10.3390/ijms21207549] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/06/2020] [Accepted: 10/09/2020] [Indexed: 12/11/2022] Open
Abstract
Protein kinases represent a very pharmacologically attractive class of targets; however, some members of the family still remain rather unexplored. The biology and therapeutic potential of cdc-like kinases (CLKs) have been explored mainly over the last decade and the first CLK inhibitor, compound SM08502, entered clinical trials only recently. This review summarizes the biological roles and therapeutic potential of CLKs and their heretofore published small-molecule inhibitors, with a focus on the compounds' potential to be utilized as quality chemical biology probes.
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16
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Prolactin-Responsive Circular RNA circHIPK3 Promotes Proliferation of Mammary Epithelial Cells from Dairy Cow. Genes (Basel) 2020; 11:genes11030336. [PMID: 32245109 PMCID: PMC7141114 DOI: 10.3390/genes11030336] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/18/2020] [Accepted: 03/18/2020] [Indexed: 12/15/2022] Open
Abstract
The highly expressed circHIPK3 is a circular RNA that has been previously reported to regulate the growth of human cells. In this study, we found an increased expression of circHIPK3 in bovine mammary epithelial cells treated with prolactin (PRL) in high-throughput sequencing data. Thus, we further investigated the effect of circHIPK3 on the proliferation and differentiation of mammary epithelial cells. We used qRT-PCR/Cell Counting Kit-8 (CCK-8) and a Western blotting analysis to evaluate the effects on cell proliferation. We found that circHIPK3 promotes the proliferation of mammary epithelial cells. The STAT5 signaling pathway was previously associated with the prolactin response and when the STAT5 was suppressed, the expression of circHIPK3 decreased. The results suggest that the response to prolactin and the associated STAT5 signaling pathway affect the expression of circHIPK3, which subsequently affects the proliferation of mammary epithelial cells in dairy cows.
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17
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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: 92] [Impact Index Per Article: 18.4] [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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18
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Rahhal R, Seto E. Emerging roles of histone modifications and HDACs in RNA splicing. Nucleic Acids Res 2019; 47:4911-4926. [PMID: 31162605 PMCID: PMC6547430 DOI: 10.1093/nar/gkz292] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 04/09/2019] [Accepted: 04/11/2019] [Indexed: 12/13/2022] Open
Abstract
Histone modifications and RNA splicing, two seemingly unrelated gene regulatory processes, greatly increase proteome diversity and profoundly influence normal as well as pathological eukaryotic cellular functions. Like many histone modifying enzymes, histone deacetylases (HDACs) play critical roles in governing cellular behaviors and are indispensable in numerous biological processes. While the association between RNA splicing and histone modifications is beginning to be recognized, a lack of knowledge exists regarding the role of HDACs in splicing. Recent studies however, reveal that HDACs interact with spliceosomal and ribonucleoprotein complexes, actively control the acetylation states of splicing-associated histone marks and splicing factors, and thereby unexpectedly could modulate splicing. Here, we review the role of histone/protein modifications and HDACs in RNA splicing and discuss the convergence of two parallel fields, which supports the argument that HDACs, and perhaps most histone modifying enzymes, are much more versatile and far more complicated than their initially proposed functions. Analogously, an HDAC-RNA splicing connection suggests that splicing is regulated by additional upstream factors and pathways yet to be defined or not fully characterized. Some human diseases share common underlying causes of aberrant HDACs and dysregulated RNA splicing and, thus, further support the potential link between HDACs and RNA splicing.
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Affiliation(s)
- Raneen Rahhal
- George Washington Cancer Center, Department of Biochemistry & Molecular Medicine, George Washington University School of Medicine & Health Sciences, Washington, DC 20037, USA
| | - Edward Seto
- George Washington Cancer Center, Department of Biochemistry & Molecular Medicine, George Washington University School of Medicine & Health Sciences, Washington, DC 20037, USA
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19
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Romero-Barrios N, Legascue MF, Benhamed M, Ariel F, Crespi M. Splicing regulation by long noncoding RNAs. Nucleic Acids Res 2018; 46:2169-2184. [PMID: 29425321 PMCID: PMC5861421 DOI: 10.1093/nar/gky095] [Citation(s) in RCA: 182] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/05/2018] [Accepted: 02/01/2018] [Indexed: 12/13/2022] Open
Abstract
Massive high-throughput sequencing techniques allowed the identification of thousands of noncoding RNAs (ncRNAs) and a plethora of different mRNA processing events occurring in higher organisms. Long ncRNAs can act directly as long transcripts or can be processed into active small si/miRNAs. They can modulate mRNA cleavage, translational repression or the epigenetic landscape of their target genes. Recently, certain long ncRNAs have been shown to play a crucial role in the regulation of alternative splicing in response to several stimuli or during disease. In this review, we focus on recent discoveries linking gene regulation by alternative splicing and its modulation by long and small ncRNAs.
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Affiliation(s)
- Natali Romero-Barrios
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
| | - Maria Florencia Legascue
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina
| | - Moussa Benhamed
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
| | - Federico Ariel
- Instituto de Agrobiotecnología del Litoral, CONICET, Universidad Nacional del Litoral, Colectora Ruta Nacional 168 km 0, 3000 Santa Fe, Argentina
| | - Martin Crespi
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, INRA, Universities Paris-Sud, Evry and Paris-Diderot, Sorbonne Paris-Cite, University of Paris-Saclay, Batiment 630, 91405 Orsay, France
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20
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Mobilization of a splicing factor through a nuclear kinase-kinase complex. Biochem J 2018; 475:677-690. [PMID: 29335301 DOI: 10.1042/bcj20170672] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/09/2018] [Accepted: 01/12/2018] [Indexed: 12/17/2022]
Abstract
The splicing of mRNA is dependent on serine-arginine (SR) proteins that are mobilized from membrane-free, nuclear speckles to the nucleoplasm by the Cdc2-like kinases (CLKs). This movement is critical for SR protein-dependent assembly of the macromolecular spliceosome. Although CLK1 facilitates such trafficking through the phosphorylation of serine-proline dipeptides in the prototype SR protein SRSF1, an unrelated enzyme known as SR protein kinase 1 (SRPK1) performs the same function but does not efficiently modify these dipeptides in SRSF1. We now show that the ability of SRPK1 to mobilize SRSF1 from speckles to the nucleoplasm is dependent on active CLK1. Diffusion from speckles is promoted by the formation of an SRPK1-CLK1 complex that facilitates dissociation of SRSF1 from CLK1 and enhances the phosphorylation of several serine-proline dipeptides in this SR protein. Down-regulation of either kinase blocks EGF-stimulated mobilization of nuclear SRSF1. These findings establish a signaling pathway that connects SRPKs to SR protein activation through the associated CLK family of kinases.
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21
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Signaling Pathways Driving Aberrant Splicing in Cancer Cells. Genes (Basel) 2017; 9:genes9010009. [PMID: 29286307 PMCID: PMC5793162 DOI: 10.3390/genes9010009] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/07/2017] [Accepted: 12/18/2017] [Indexed: 12/17/2022] Open
Abstract
Aberrant profiles of pre-mRNA splicing are frequently observed in cancer. At the molecular level, an altered profile results from a complex interplay between chromatin modifications, the transcriptional elongation rate of RNA polymerase, and effective binding of the spliceosome to the generated transcripts. Key players in this interplay are regulatory splicing factors (SFs) that bind to gene-specific splice-regulatory sequence elements. Although mutations in genes of some SFs were described, a major driver of aberrant splicing profiles is oncogenic signal transduction pathways. Signaling can affect either the transcriptional expression levels of SFs or the post-translational modification of SF proteins, and both modulate the ratio of nuclear versus cytoplasmic SFs in a given cell. Here, we will review currently known mechanisms by which cancer cell signaling, including the mitogen-activated protein kinases (MAPK), phosphatidylinositol 3 (PI3)-kinase pathway (PI3K) and wingless (Wnt) pathways but also signals from the tumor microenvironment, modulate the activity or subcellular localization of the Ser/Arg rich (SR) proteins and heterogeneous nuclear ribonucleoproteins (hnRNPs) families of SFs.
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22
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Kajitani N, Glahder J, Wu C, Yu H, Nilsson K, Schwartz S. hnRNP L controls HPV16 RNA polyadenylation and splicing in an Akt kinase-dependent manner. Nucleic Acids Res 2017; 45:9654-9678. [PMID: 28934469 PMCID: PMC5766200 DOI: 10.1093/nar/gkx606] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 07/04/2017] [Indexed: 11/14/2022] Open
Abstract
Inhibition of the Akt kinase activates HPV16 late gene expression by reducing HPV16 early polyadenylation and by activating HPV16 late L1 mRNA splicing. We identified ‘hot spots’ for RNA binding proteins at the early polyA signal and at splice sites on HPV16 late mRNAs. We observed that hnRNP L was associated with sequences at all HPV16 late splice sites and at the early polyA signal. Akt kinase inhibition resulted in hnRNP L dephosphorylation and reduced association of hnRNP L with HPV16 mRNAs. This was accompanied by an increased binding of U2AF65 and Sam68 to HPV16 mRNAs. Furthermore, siRNA knock-down of hnRNP L or Akt induced HPV16 gene expression. Treatment of HPV16 immortalized keratinocytes with Akt kinase inhibitor reduced hnRNP L binding to HPV16 mRNAs and induced HPV16 L1 mRNA production. Finally, deletion of the hnRNP L binding sites in HPV16 subgenomic expression plasmids resulted in activation of HPV16 late gene expression. In conclusion, the Akt kinase inhibits HPV16 late gene expression at the level of RNA processing by controlling the RNA-binding protein hnRNP L. We speculate that Akt kinase activity upholds an intracellular milieu that favours HPV16 early gene expression and suppresses HPV16 late gene expression.
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Affiliation(s)
- Naoko Kajitani
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Jacob Glahder
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Chengjun Wu
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Haoran Yu
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Kersti Nilsson
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
| | - Stefan Schwartz
- Department of Laboratory Medicine, Lund University, BMC-B13, 223 62 Lund, Sweden
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23
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Belfiore A, Malaguarnera R, Vella V, Lawrence MC, Sciacca L, Frasca F, Morrione A, Vigneri R. Insulin Receptor Isoforms in Physiology and Disease: An Updated View. Endocr Rev 2017; 38:379-431. [PMID: 28973479 PMCID: PMC5629070 DOI: 10.1210/er.2017-00073] [Citation(s) in RCA: 234] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/13/2017] [Indexed: 02/08/2023]
Abstract
The insulin receptor (IR) gene undergoes differential splicing that generates two IR isoforms, IR-A and IR-B. The physiological roles of IR isoforms are incompletely understood and appear to be determined by their different binding affinities for insulin-like growth factors (IGFs), particularly for IGF-2. Predominant roles of IR-A in prenatal growth and development and of IR-B in metabolic regulation are well established. However, emerging evidence indicates that the differential expression of IR isoforms may also help explain the diversification of insulin and IGF signaling and actions in various organs and tissues by involving not only different ligand-binding affinities but also different membrane partitioning and trafficking and possibly different abilities to interact with a variety of molecular partners. Of note, dysregulation of the IR-A/IR-B ratio is associated with insulin resistance, aging, and increased proliferative activity of normal and neoplastic tissues and appears to sustain detrimental effects. This review discusses novel information that has generated remarkable progress in our understanding of the physiology of IR isoforms and their role in disease. We also focus on novel IR ligands and modulators that should now be considered as an important strategy for better and safer treatment of diabetes and cancer and possibly other IR-related diseases.
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Affiliation(s)
- Antonino Belfiore
- Endocrinology, Department of Health Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Roberta Malaguarnera
- Endocrinology, Department of Health Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Veronica Vella
- School of Human and Social Sciences, University Kore of Enna, via della Cooperazione, 94100 Enna, Italy
| | - Michael C. Lawrence
- Structural Biology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Laura Sciacca
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
| | - Francesco Frasca
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
| | - Andrea Morrione
- Department of Urology and Biology of Prostate Cancer Program, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
| | - Riccardo Vigneri
- Endocrinology, Department of Clinical and Experimental Medicine, University of Catania, Garibaldi-Nesima Hospital, 95122 Catania, Italy
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24
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Lee CC, Chang WH, Chang YS, Liu TY, Chen YC, Wu YC, Chang JG. 4β-Hydroxywithanolide E Modulates Alternative Splicing of Apoptotic Genes in Human Hepatocellular Carcinoma Huh-7 Cells. Sci Rep 2017; 7:7290. [PMID: 28779122 PMCID: PMC5544667 DOI: 10.1038/s41598-017-07472-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 06/27/2017] [Indexed: 01/31/2023] Open
Abstract
Alternative splicing is a mechanism for increasing protein diversity from a limited number of genes. Studies have demonstrated that aberrant regulation in the alternative splicing of apoptotic gene transcripts may contribute to the development of cancer. In this study, we isolated 4β-Hydroxywithanolide E (4bHWE) from the traditional herb Physalis peruviana and investigated its biological effect in cancer cells. The results demonstrated that 4bHWE modulates the alternative splicing of various apoptotic genes, including HIPK3, SMAC/DIABLO, and SURVIVIN. We also discovered that the levels of SRSF1 phospho-isoform were decreased and the levels of H3K36me3 were increased in 4bHWE treatment. Knockdown experiments revealed that the splicing site selection of SMAC/DIABLO could be mediated by changes in the level of H3K36me3 in 4bHWE-treated cells. Furthermore, we extended our study to apoptosis-associated molecules, and detected increased levels of poly ADP-ribose polymerase cleavage and the active form of CASPASE-3 in 4bHWE-induced apoptosis. In vivo experiments indicated that the treatment of tumor-bearing mice with 4bHWE resulted in a marked decrease in tumor size. This study is the first to demonstrate that 4bHWE affects alternative splicing by modulating splicing factors and histone modifications, and provides a novel view of the antitumor mechanism of 4bHWE.
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Affiliation(s)
- Chien-Chin Lee
- Epigenome Research Center, China Medical University Hospital, Taichung, Taiwan
| | - Wen-Hsin Chang
- Department of Primary Care Medicine, Taipei Medical University Hospital, Taipei, Taiwan
| | - Ya-Sian Chang
- Epigenome Research Center, China Medical University Hospital, Taichung, Taiwan.,Department of Laboratory Medicine, China Medical University Hospital, Taichung, Taiwan.,Center for Precision Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Ting-Yuan Liu
- Center for Precision Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Yu-Chia Chen
- Center for Precision Medicine, China Medical University Hospital, Taichung, Taiwan
| | - Yang-Chang Wu
- Graduate Institute of Natural Products, Kaohsiung Medical University, Kaohsiung, Taiwan. .,Research Center for Natural Products and Drug Development, Kaohsiung Medical University, Kaohsiung, Taiwan. .,Chinese Medicine Research and Development Center, China Medical University Hospital, Taichung, Taiwan.
| | - Jan-Gowth Chang
- Epigenome Research Center, China Medical University Hospital, Taichung, Taiwan. .,Department of Laboratory Medicine, China Medical University Hospital, Taichung, Taiwan. .,Center for Precision Medicine, China Medical University Hospital, Taichung, Taiwan. .,Department of Bioinformatics and Medical Engineering, Asia University, Taichung, Taiwan.
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25
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Insulin regulates titin pre-mRNA splicing through the PI3K-Akt-mTOR kinase axis in a RBM20-dependent manner. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2363-2371. [PMID: 28676430 DOI: 10.1016/j.bbadis.2017.06.023] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/25/2017] [Accepted: 06/29/2017] [Indexed: 12/13/2022]
Abstract
Titin, a giant sarcomeric protein, is largely responsible for the diastolic properties of the heart. It has two major isoforms, N2B and N2BA due to pre-mRNA splicing regulated mainly by a splicing factor RNA binding motif 20 (RBM20). Mis-splicing of titin pre-mRNA in response to external stimuli may lead to altered ratio of N2B to N2BA, and thus, impaired cardiac contractile function. However, little is known about titin alternative splicing in response to external stimuli. Here, we reported the detailed mechanisms of titin alternative splicing in response to insulin. Insulin treatment in cultured neonatal rat cardiomyocytes (NRCMs) activated the PI3K-Akt-mTOR kinase axis, leading to increased N2B expression in the presence of RBM20, but not in NRCMs in the absence of RBM20. By inhibiting this kinase axis with inhibitors, decreased N2B isoform was observed in NRCMs and also in diabetic rat model treated with streptozotocin, but not in NRCMs and diabetic rats in the absence of RBM20. In addition to the alteration of titin isoform ratios in response to insulin, we found that RBM20 expression was increased in NRCMs with insulin treatment, suggesting that RBM20 levels were also regulated by insulin-induced kinase axis. Further, knockdown of p70S6K1 with siRNA reduced both RBM20 and N2B levels, while knockdown of 4E-BP1 elevated expression levels of RBM20 and N2B. These findings reveal a major signal transduction pathway for insulin-induced titin alternative splicing, and place RBM20 in a central position in the pathway, which is consistent with the reputed role of RBM20 in titin alternative splicing. Findings from this study shed light on gene therapeutic strategies at the molecular level by correction of pre-mRNA mis-splicing.
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26
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Czubaty A, Piekiełko-Witkowska A. Protein kinases that phosphorylate splicing factors: Roles in cancer development, progression and possible therapeutic options. Int J Biochem Cell Biol 2017; 91:102-115. [PMID: 28552434 DOI: 10.1016/j.biocel.2017.05.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/16/2017] [Accepted: 05/18/2017] [Indexed: 11/30/2022]
Abstract
Disturbed alternative splicing is a common feature of human tumors. Splicing factors that control alternative splicing are phosphorylated by multiple kinases, including these that specifically add phosphoryl groups to serine-arginine rich proteins (e.g. SR-protein kinases, cdc2-like kinases, topoisomerase 1), and protein kinases that govern key cellular signaling pathways (i.e. AKT). Phosphorylation of splicing factors regulates their subcellular localization and interactions with target transcripts and protein partners, and thus significantly contributes the final result of splicing reactions. In this review we aim to summarize the current knowledge on the role of splicing kinases in cancer. Published studies and recently released data of The Cancer Genome Atlas demonstrate that expressions and activities of splicing kinases are commonly disturbed in cancers. Aberrant functioning of splicing kinases results in changed alternative splicing of tumor suppressors (e.g. p53) and regulators of cell signaling (e.g. MAPKs), apoptosis (e.g. MCL), and angiogenesis (VEGF). Splicing kinases act in complicated regulatory networks in which they mutually affect each other's activity to provide tight control of cellular signaling. Dysregulation of these regulatory networks contributes to oncogenic transformation, uncontrolled proliferation, enhanced migration and invasion. Furthermore, the activities of splicing kinases significantly contribute to cellular responses to genotoxic stress. In conclusion, published data provide strong evidence that splicing kinases emerge as important regulators of key processes governing malignant transformation, progression, and response to therapeutic treatments, suggesting their potential as clinically relevant targets.
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Affiliation(s)
- Alicja Czubaty
- Department of Molecular Biology, Faculty of Biology, University of Warsaw, ul. Miecznikowa 1, 02-096 Warsaw, Poland
| | - Agnieszka Piekiełko-Witkowska
- Department of Biochemistry and Molecular Biology, Centre of Postgraduate Medical Education, ul. Marymoncka 99/103, 01-813 Warsaw, Poland.
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27
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Kozlovski I, Siegfried Z, Amar-Schwartz A, Karni R. The role of RNA alternative splicing in regulating cancer metabolism. Hum Genet 2017; 136:1113-1127. [PMID: 28429085 DOI: 10.1007/s00439-017-1803-x] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 04/13/2017] [Indexed: 12/12/2022]
Abstract
Tumor cells alter their metabolism by a wide array of mechanisms to promote growth and proliferation. Dysregulated expression and/or somatic mutations of key components of the glycolytic pathway/TCA cycle as well as other metabolic pathways allow tumor cells to improve their ability to survive harsh conditions such as hypoxia and the presence of reactive oxygen species, as well as the ability to obtain nutrients to increase lipids, protein, and nucleic acids biogenesis. Approximately 95% of the human protein encoding genes undergo alternative splicing (AS), a regulated process of gene expression that greatly diversifies the proteome by creating multiple proteins from a single gene. In recent years, a growing body of evidence suggests that unbalanced AS, the formation of certain pro-tumorigenic isoforms and the reduction of anti-tumorigenic isoforms, is implicated in a variety of cancers. It is becoming increasingly clear that cancer-associated AS contributes to increased growth and proliferation, partially due to effects on metabolic reprogramming. Here, we summarize the known roles of AS in regulating cancer metabolism. We present evidence supporting the idea that AS, in many types of cancer, acts as a molecular switch that alters metabolism to drive tumorigenesis. We propose that the elucidation of misregulated AS and its downstream effects on cancer metabolism emphasizes the need for new therapeutic approaches aiming to modulate the splicing machinery to selectively target cancer cells.
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Affiliation(s)
- Itamar Kozlovski
- Department of Biochemistry and Molecular Biology, IMRIC, Hebrew University-Hadassah Medical School, Ein Karem, 91120, Jerusalem, Israel
| | - Zahava Siegfried
- Department of Biochemistry and Molecular Biology, IMRIC, Hebrew University-Hadassah Medical School, Ein Karem, 91120, Jerusalem, Israel
| | - Adi Amar-Schwartz
- Department of Biochemistry and Molecular Biology, IMRIC, Hebrew University-Hadassah Medical School, Ein Karem, 91120, Jerusalem, Israel
| | - Rotem Karni
- Department of Biochemistry and Molecular Biology, IMRIC, Hebrew University-Hadassah Medical School, Ein Karem, 91120, Jerusalem, Israel.
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28
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Mohammad DK, Ali RH, Turunen JJ, Nore BF, Smith CIE. B Cell Receptor Activation Predominantly Regulates AKT-mTORC1/2 Substrates Functionally Related to RNA Processing. PLoS One 2016; 11:e0160255. [PMID: 27487157 PMCID: PMC4972398 DOI: 10.1371/journal.pone.0160255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 07/16/2016] [Indexed: 12/19/2022] Open
Abstract
Protein kinase B (AKT) phosphorylates numerous substrates on the consensus motif RXRXXpS/T, a docking site for 14-3-3 interactions. To identify novel AKT-induced phosphorylation events following B cell receptor (BCR) activation, we performed proteomics, biochemical and bioinformatics analyses. Phosphorylated consensus motif-specific antibody enrichment, followed by tandem mass spectrometry, identified 446 proteins, containing 186 novel phosphorylation events. Moreover, we found 85 proteins with up regulated phosphorylation, while in 277 it was down regulated following stimulation. Up regulation was mainly in proteins involved in ribosomal and translational regulation, DNA binding and transcription regulation. Conversely, down regulation was preferentially in RNA binding, mRNA splicing and mRNP export proteins. Immunoblotting of two identified RNA regulatory proteins, RBM25 and MEF-2D, confirmed the proteomics data. Consistent with these findings, the AKT-inhibitor (MK-2206) dramatically reduced, while the mTORC-inhibitor PP242 totally blocked phosphorylation on the RXRXXpS/T motif. This demonstrates that this motif, previously suggested as an AKT target sequence, also is a substrate for mTORC1/2. Proteins with PDZ, PH and/or SH3 domains contained the consensus motif, whereas in those with an HMG-box, H15 domains and/or NF-X1-zinc-fingers, the motif was absent. Proteins carrying the consensus motif were found in all eukaryotic clades indicating that they regulate a phylogenetically conserved set of proteins.
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Affiliation(s)
- Dara K. Mohammad
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska Hospital Huddinge, SE-141 86 Huddinge-Stockholm, Sweden
- Department of Biology, College of Science, University of Salahaddin, 44002 Erbil, Kurdistan Region-Iraq
- * E-mail: ; (DKM); (CIES)
| | - Raja H. Ali
- KTH Royal Institute of Technology, Swedish e-Science Research Center, Science for Life Laboratory, School of Computer Science and Communication, SE-171 77 Solna, Sweden
| | - Janne J. Turunen
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska Hospital Huddinge, SE-141 86 Huddinge-Stockholm, Sweden
| | - Beston F. Nore
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska Hospital Huddinge, SE-141 86 Huddinge-Stockholm, Sweden
- Department of Biochemistry, School of Medicine, University of Sulaimani, Sulaimaniyah, Kurdistan Region-Iraq
| | - C. I. Edvard Smith
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska Hospital Huddinge, SE-141 86 Huddinge-Stockholm, Sweden
- * E-mail: ; (DKM); (CIES)
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29
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D’Souza SA, Rajendran L, Bagg R, Barbier L, van Pel DM, Moshiri H, Roy PJ. The MADD-3 LAMMER Kinase Interacts with a p38 MAP Kinase Pathway to Regulate the Display of the EVA-1 Guidance Receptor in Caenorhabditis elegans. PLoS Genet 2016; 12:e1006010. [PMID: 27123983 PMCID: PMC4849719 DOI: 10.1371/journal.pgen.1006010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 04/05/2016] [Indexed: 11/25/2022] Open
Abstract
The proper display of transmembrane receptors on the leading edge of migrating cells and cell extensions is essential for their response to guidance cues. We previously discovered that MADD-4, which is an ADAMTSL secreted by motor neurons in Caenorhabditis elegans, interacts with an UNC-40/EVA-1 co-receptor complex on muscles to attract plasma membrane extensions called muscle arms. In nematodes, the muscle arm termini harbor the post-synaptic elements of the neuromuscular junction. Through a forward genetic screen for mutants with disrupted muscle arm extension, we discovered that a LAMMER kinase, which we call MADD-3, is required for the proper display of the EVA-1 receptor on the muscle’s plasma membrane. Without MADD-3, EVA-1 levels decrease concomitantly with a reduction of the late-endosomal marker RAB-7. Through a genetic suppressor screen, we found that the levels of EVA-1 and RAB-7 can be restored in madd-3 mutants by eliminating the function of a p38 MAP kinase pathway. We also found that EVA-1 and RAB-7 will accumulate in madd-3 mutants upon disrupting CUP-5, which is a mucolipin ortholog required for proper lysosome function. Together, our data suggests that the MADD-3 LAMMER kinase antagonizes the p38-mediated endosomal trafficking of EVA-1 to the lysosome. In this way, MADD-3 ensures that sufficient levels of EVA-1 are present to guide muscle arm extension towards the source of the MADD-4 guidance cue. In most animals, the physical meeting of the pre- and post-synaptic membranes of the neuromuscular junction occurs via axonal extension towards the muscle. In nematodes, however, motor axons do not extend towards the muscle and instead form a dorsal and ventral cord with relatively few branches. To make the physical connection, the body wall muscles extend membrane projections called muscle arms to the motor axons within the dorsal and ventral cords. Through previous genetic and biochemical analyses with the nematode C. elegans, we identified a neuronally-expressed muscle arm chemoattractant (MADD-4) and its muscle-expressed co-receptor complex (UNC-40/EVA-1). Here, we report our discovery of madd-3, which encodes a LAMMER kinase that is expressed in muscles to regulate muscle arm extension. Genetic analyses revealed that MADD-3 may inhibit a p38 MAP kinase pathway whose normal function is to decrease the abundance of the EVA-1 receptor. In the presence of MADD-3, the activity of the p38 pathway is relatively low, and EVA-1 levels are consequently relatively high. Without MADD-3, the p38 pathway is freed to decrease the abundance of EVA-1. The relationships that we have uncovered between MADD-3, the p38 Map Kinase pathway, and the EVA-1 receptor provide one explanation for the muscle arm defects observed in madd-3 mutants.
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Affiliation(s)
- Serena A. D’Souza
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- The Collaborative Programme in Developmental Biology, University of Toronto, Toronto, Ontario, Canada
| | - Luckshi Rajendran
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Rachel Bagg
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Louis Barbier
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Derek M. van Pel
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Houtan Moshiri
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
| | - Peter J. Roy
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- The Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada
- The Collaborative Programme in Developmental Biology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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30
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Voukkalis N, Koutroumani M, Zarkadas C, Nikolakaki E, Vlassi M, Giannakouros T. SRPK1 and Akt Protein Kinases Phosphorylate the RS Domain of Lamin B Receptor with Distinct Specificity: A Combined Biochemical and In Silico Approach. PLoS One 2016; 11:e0154198. [PMID: 27105349 PMCID: PMC4841541 DOI: 10.1371/journal.pone.0154198] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 04/10/2016] [Indexed: 02/03/2023] Open
Abstract
Activated Akt has been previously implicated in acting on RS domain-containing proteins. However, it has been questioned whether its action is direct or it is mediated by co-existing SR kinase activity. To address this issue we studied in detail the phosphorylation of Lamin B Receptor (LBR) by Akt. Using synthetic peptides and a set of recombinant proteins expressing mutants of the LBR RS domain we now demonstrate that while all serines of the RS domain represent more or less equal phosphoacceptor sites for SRPK1, Ser80 and Ser82 are mainly targeted by Akt. 3D-modeling combined with molecular dynamics (MD) simulations show that amongst short, overlapping LBR RS-containing peptides complying with the minimum Akt recognition consensus sequence, only those bearing phosphosites either at Ser80 or Ser82 are able to fit into the active site of Akt, at least as effectively as its known substrate, GSK3-β. Combined our results provide evidence that Akt kinases directly phosphorylate an RS domain-containing protein and that both the residues N-terminal the phosphosite and at position +1 are essential for Akt specificity, with the latter substrate position being compatible with the arginine residue of RS-repeats.
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Affiliation(s)
- Nikolaos Voukkalis
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University, Thessaloniki, Greece
| | - Maria Koutroumani
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University, Thessaloniki, Greece
| | - Christoforos Zarkadas
- Institute of Biosciences & Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Eleni Nikolakaki
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University, Thessaloniki, Greece
| | - Metaxia Vlassi
- Institute of Biosciences & Applications, National Centre for Scientific Research "Demokritos", Athens, Greece
| | - Thomas Giannakouros
- Laboratory of Biochemistry, Department of Chemistry, Aristotle University, Thessaloniki, Greece
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31
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Dominguez D, Tsai YH, Weatheritt R, Wang Y, Blencowe BJ, Wang Z. An extensive program of periodic alternative splicing linked to cell cycle progression. eLife 2016; 5. [PMID: 27015110 PMCID: PMC4884079 DOI: 10.7554/elife.10288] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 03/24/2016] [Indexed: 12/28/2022] Open
Abstract
Progression through the mitotic cell cycle requires periodic regulation of gene function at the levels of transcription, translation, protein-protein interactions, post-translational modification and degradation. However, the role of alternative splicing (AS) in the temporal control of cell cycle is not well understood. By sequencing the human transcriptome through two continuous cell cycles, we identify ~1300 genes with cell cycle-dependent AS changes. These genes are significantly enriched in functions linked to cell cycle control, yet they do not significantly overlap genes subject to periodic changes in steady-state transcript levels. Many of the periodically spliced genes are controlled by the SR protein kinase CLK1, whose level undergoes cell cycle-dependent fluctuations via an auto-inhibitory circuit. Disruption of CLK1 causes pleiotropic cell cycle defects and loss of proliferation, whereas CLK1 over-expression is associated with various cancers. These results thus reveal a large program of CLK1-regulated periodic AS intimately associated with cell cycle control.
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Affiliation(s)
- Daniel Dominguez
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, United States.,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Yi-Hsuan Tsai
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, United States.,Program in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Robert Weatheritt
- Donnelly Centre and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Yang Wang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, United States.,Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Benjamin J Blencowe
- Donnelly Centre and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Zefeng Wang
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, United States.,Key Lab of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Chinese Academy of Science, Shanghai, China
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32
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Jiang W, Li Z, Zhao W, Chen H, Wu Y, Wang Y, Shen Z, He J, Chen S, Zhang J, Fu G. Breviscapine attenuatted contrast medium-induced nephropathy via PKC/Akt/MAPK signalling in diabetic mice. Am J Transl Res 2016; 8:329-341. [PMID: 27158329 PMCID: PMC4846886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 01/02/2016] [Indexed: 06/05/2023]
Abstract
Contrast medium-induced nephropathy (CIN) remains a major cause of iatrogenic, drug-induced renal injury. Recent studies reveal that Breviscapine can ameliorate diabetic nephropathy in mice. Yet it remains unknown if Breviscapine could reduce CIN in diabetic mice. In this study, male C57/BL6J mice were randomly divided into 7 groups: control, diabetes mellitus, CIN, diabetes mellitus+CIN, diabetes mellitus+Breviscapine, CIN+Breviscapine and diabetes mellitus+CIN+Breviscapine. Model of CIN was induced by tail intravenous administration of iopromide and model of diabetes mellitus was induced by Streptozotocin intraperitoneally. Breviscapine was administered intragastrically for 4 weeks. Renal function parameters, kidney histology, markers of renal fibrosis, phosphorylation of protein kinase C/Akt/mitogen activated protein kinases were measured by western blot. We found out that diabetes mellitus aggravated CIN damage. Renal histological analysis showed Breviscapine reduced of renal fibrosis and tubular damage. Breviscapine was also shown markedly to ameliorate CIN fibrotic markers expression, reduced proteinuria and serum creatinine. Furthermore, Breviscapine decreased phosphorylation of PKCβII, Akt, JNK1/2 and p38. Therefore, Breviscapine treatment could ameliorate the development of CIN in diabetic mice, which was partly attributed to its suppression of renal fibrosis via phosphorylation of PKCβII/Akt/JNK1/2/p38 signalling.
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Affiliation(s)
- Wenbin Jiang
- Department of Cardiology, The Third Clinical Institute Affiliated To Wenzhou Medical UniversityNo. 57 Canghou Street, Wenzhou 325000, Zhejiang Province, PR China
| | - Zhengwei Li
- Department of Cardiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang UniversityNo. 3 East Qingchun Road, Hangzhou 310016, Zhejiang Province, PR China
| | - Wei Zhao
- Department of Cardiology, The Third Clinical Institute Affiliated To Wenzhou Medical UniversityNo. 57 Canghou Street, Wenzhou 325000, Zhejiang Province, PR China
| | - Hao Chen
- Department of Cardiology, The Third Clinical Institute Affiliated To Wenzhou Medical UniversityNo. 57 Canghou Street, Wenzhou 325000, Zhejiang Province, PR China
| | - Youyang Wu
- Department of Cardiology, The Third Clinical Institute Affiliated To Wenzhou Medical UniversityNo. 57 Canghou Street, Wenzhou 325000, Zhejiang Province, PR China
| | - Yi Wang
- Department of Cardiology, The Third Clinical Institute Affiliated To Wenzhou Medical UniversityNo. 57 Canghou Street, Wenzhou 325000, Zhejiang Province, PR China
| | - Zhida Shen
- Department of Cardiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang UniversityNo. 3 East Qingchun Road, Hangzhou 310016, Zhejiang Province, PR China
| | - Jialin He
- Department of Cardiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang UniversityNo. 3 East Qingchun Road, Hangzhou 310016, Zhejiang Province, PR China
| | - Shengyu Chen
- Department of Cardiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang UniversityNo. 3 East Qingchun Road, Hangzhou 310016, Zhejiang Province, PR China
| | - Jiefang Zhang
- Department of Cardiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang UniversityNo. 3 East Qingchun Road, Hangzhou 310016, Zhejiang Province, PR China
| | - Guosheng Fu
- Department of Cardiology, Sir Run Run Shaw Hospital, College of Medicine, Zhejiang UniversityNo. 3 East Qingchun Road, Hangzhou 310016, Zhejiang Province, PR China
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Dlamini Z, Tshidino SC, Hull R. Abnormalities in Alternative Splicing of Apoptotic Genes and Cardiovascular Diseases. Int J Mol Sci 2015; 16:27171-90. [PMID: 26580598 PMCID: PMC4661875 DOI: 10.3390/ijms161126017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 08/06/2015] [Accepted: 08/17/2015] [Indexed: 01/23/2023] Open
Abstract
Apoptosis is required for normal heart development in the embryo, but has also been shown to be an important factor in the occurrence of heart disease. Alternative splicing of apoptotic genes is currently emerging as a diagnostic and therapeutic target for heart disease. This review addresses the involvement of abnormalities in alternative splicing of apoptotic genes in cardiac disorders including cardiomyopathy, myocardial ischemia and heart failure. Many pro-apoptotic members of the Bcl-2 family have alternatively spliced isoforms that lack important active domains. These isoforms can play a negative regulatory role by binding to and inhibiting the pro-apoptotic forms. Alternative splicing is observed to be increased in various cardiovascular diseases with the level of alternate transcripts increasing elevated in diseased hearts compared to healthy subjects. In many cases these isoforms appear to be the underlying cause of the disease, while in others they may be induced in response to cardiovascular pathologies. Regardless of this, the detection of alternate splicing events in the heart can serve as useful diagnostic or prognostic tools, while those splicing events that seem to play a causative role in cardiovascular disease make attractive future drug targets.
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Affiliation(s)
- Zodwa Dlamini
- Research, Innovation and Engagements, Mangosuthu University of Technology, Durban 4026, South Africa.
| | - Shonisani C Tshidino
- Department of Biochemistry, Microbiology and Biotechnology, University of Limpopo, Polokwane 0727, South Africa.
| | - Rodney Hull
- College of Agriculture and Environmental Sciences, Department of Life and Consumer Sciences, Florida Science Campus, University of South Africa, Johannesburg 1709, South Africa.
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34
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Posttranscriptional Regulation of Splicing Factor SRSF1 and Its Role in Cancer Cell Biology. BIOMED RESEARCH INTERNATIONAL 2015; 2015:287048. [PMID: 26273603 PMCID: PMC4529898 DOI: 10.1155/2015/287048] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 12/16/2014] [Indexed: 01/23/2023]
Abstract
Over the past decade, alternative splicing has been progressively recognized as a major mechanism regulating gene expression patterns in different tissues and disease states through the generation of multiple mRNAs from the same gene transcript. This process requires the joining of selected exons or usage of different pairs of splice sites and is regulated by gene-specific combinations of RNA-binding proteins. One archetypical splicing regulator is SRSF1, for which we review the molecular mechanisms and posttranscriptional modifications involved in its life cycle. These include alternative splicing of SRSF1 itself, regulatory protein phosphorylation events, and the role of nuclear versus cytoplasmic SRSF1 localization. In addition, we resume current knowledge on deregulated SRSF1 expression in tumors and describe SRSF1-regulated alternative transcripts with functional consequences for cancer cell biology at different stages of tumor development.
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35
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Conserved proline-directed phosphorylation regulates SR protein conformation and splicing function. Biochem J 2015; 466:311-22. [PMID: 25529026 DOI: 10.1042/bj20141373] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The alternative splicing of human genes is dependent on SR proteins, a family of essential splicing factors whose name derives from a signature C-terminal domain rich in arginine-serine dipeptide repeats (RS domains). Although the SRPKs (SR-specific protein kinases) phosphorylate these repeats, RS domains also contain prolines with flanking serines that are phosphorylated by a second family of protein kinases known as the CLKs (Cdc2-like kinases). The role of specific serine-proline phosphorylation within the RS domain has been difficult to assign since CLKs also phosphorylate arginine-serine dipeptides and, thus, display overlapping residue specificities with the SRPKs. In the present study, we address the effects of discrete serine-proline phosphorylation on the conformation and cellular function of the SR protein SRSF1 (SR protein splicing factor 1). Using chemical tagging and dephosphorylation experiments, we show that modification of serine-proline dipeptides broadly amplifies the conformational ensemble of SRSF1. The induction of these new structural forms triggers SRSF1 mobilization in the nucleus and alters its binding mechanism to an exonic splicing enhancer in precursor mRNA. These physical events correlate with changes in the alternative splicing of over 100 human genes based on a global splicing assay. Overall, these studies draw a direct causal relationship between a specific type of chemical modification in an SR protein and the regulation of alternative gene splicing programmes.
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Boutz PL, Bhutkar A, Sharp PA. Detained introns are a novel, widespread class of post-transcriptionally spliced introns. Genes Dev 2015; 29:63-80. [PMID: 25561496 PMCID: PMC4281565 DOI: 10.1101/gad.247361.114] [Citation(s) in RCA: 275] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Deep sequencing of embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within polyadenylated transcripts. Boutz et al. identified thousands of these “detained” introns (DIs) in human and mouse cell lines as well as the adult mouse liver. Drug inhibition of Clk, a stress-responsive kinase, triggered rapid splicing changes for a specific subset of DIs, altering transcript pools of >300 genes. Srsf4 regulates the splicing of some DIs, particularly in genes encoding RNA processing and splicing factors. Deep sequencing of embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within polyadenylated transcripts; we classified these as “detained” introns (DIs). We identified thousands of DIs, many of which are evolutionarily conserved, in human and mouse cell lines as well as the adult mouse liver. DIs can have half-lives of over an hour yet remain in the nucleus and are not subject to nonsense-mediated decay (NMD). Drug inhibition of Clk, a stress-responsive kinase, triggered rapid splicing changes for a specific subset of DIs; half showed increased splicing, and half showed increased intron detention, altering transcript pools of >300 genes. Srsf4, which undergoes a dramatic phosphorylation shift in response to Clk kinase inhibition, regulates the splicing of some DIs, particularly in genes encoding RNA processing and splicing factors. The splicing of some DIs—including those in Mdm4, a negative regulator of p53—was also altered following DNA damage. After 4 h of Clk inhibition, the expression of >400 genes changed significantly, and almost one-third of these are p53 transcriptional targets. These data suggest a widespread mechanism by which the rate of splicing of DIs contributes to the level of gene expression.
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Affiliation(s)
- Paul L Boutz
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Arjun Bhutkar
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Phillip A Sharp
- The David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Long Non-Coding RNA NEAT1 Associates with SRp40 to Temporally Regulate PPARγ2 Splicing during Adipogenesis in 3T3-L1 Cells. Genes (Basel) 2014; 5:1050-63. [PMID: 25437750 PMCID: PMC4276926 DOI: 10.3390/genes5041050] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 10/15/2014] [Accepted: 10/22/2014] [Indexed: 01/18/2023] Open
Abstract
Long non-coding (lnc) RNAs serve a multitude of functions in cells. NEAT1 RNA is a highly abundant 4 kb lncRNA in nuclei, and coincides with paraspeckles, nuclear domains that control sequestration of paraspeckle proteins. We examined NEAT1 RNA levels and its function in 3T3-L1 cells during differentiation to adipocytes. Levels of NEAT1 transcript, measured by RT-PCR, fluctuated in a temporal manner over the course of differentiation that suggested its role in alternative splicing of PPARγ mRNA, the major transcription factor driving adipogenesis. When cells were induced to differentiate by a media cocktail of insulin, dexamethasone, and isobutylmethyxanthine (IBMX) on Day 0, NEAT1 levels dropped on Day 4, when the PPARγ2 variant was spliced and when terminal differentiation occurs The appearance of PPARγ2 coordinates with the PPARγ1 variant to drive differentiation of adipocytes. SiRNA used to deplete NEAT1 resulted in the inability of cells to phosphorylate the serine/arginine-rich splicing protein, SRp40. SiRNA treatment for SRp40 resulted in dysregulation of PPARγ1 and, primarily, PPARγ2 mRNA levels. SRp40 associated with NEAT1, as shown by RNA-IP on days 0 and 8, but decreased on day 4, and concentrations increased over that of IgG control. Overexpression of SRp40 increased PPARγ2, but not γ1. Although lncRNA MALAT1 has been investigated in SR protein function, NEAT1 has not been shown to bind SR proteins for phosphorylation such that alternative splicing results. The ability of cells to increase phosphorylated SR proteins for PPARγ2 splicing suggests that fluxes in NEAT1 levels during adipogenesis regulate alternative splicing events.
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Schmitt C, Miralinaghi P, Mariano M, Hartmann RW, Engel M. Hydroxybenzothiophene Ketones Are Efficient Pre-mRNA Splicing Modulators Due to Dual Inhibition of Dyrk1A and Clk1/4. ACS Med Chem Lett 2014; 5:963-7. [PMID: 25221649 DOI: 10.1021/ml500059y] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 07/14/2014] [Indexed: 12/20/2022] Open
Abstract
Dysregulated usage of pre-mRNA splicing sites contributes to the progression of cancer, neurodegenerative diseases, and viral infections. Serine/arginine-rich (SR) proteins play major roles in the splice site recognition and are largely regulated by phosphorylation. This provides an option for the pharmacological correction of aberrant splicing by inhibiting the relevant kinases. Cdc2-like kinases (Clks) and dual specificity tyrosine phosphorylation-regulated kinases (Dyrks) were both reported to phosphorylate numerous SR proteins in vitro and in vivo. In this study, we describe the discovery of new selective dual Clk/Dyrk1A/1B inhibitors, which are able to modulate alternative pre-mRNA splicing of model gene transcripts in cells with submicromolar potencies. The optimization process yielded a dual Clk and Dyrk inhibitor with exceptionally high ligand efficiency. Our results suggested that dual inhibition of both Clk1 and Dyrk1A increased the efficacy of pre-mRNA splicing modulation.
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Affiliation(s)
- Christian Schmitt
- Pharmaceutical
and Medicinal Chemistry, Saarland University, Campus C2.3, D-66123 Saarbrücken, Germany
| | - Parisa Miralinaghi
- Pharmaceutical
and Medicinal Chemistry, Saarland University, Campus C2.3, D-66123 Saarbrücken, Germany
| | - Marica Mariano
- Pharmaceutical
and Medicinal Chemistry, Saarland University, Campus C2.3, D-66123 Saarbrücken, Germany
| | - Rolf W. Hartmann
- Pharmaceutical
and Medicinal Chemistry, Saarland University, Campus C2.3, D-66123 Saarbrücken, Germany
- Department
of Drug Design and Optimization, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Campus C2.3, D-66123 Saarbrücken, Germany
| | - Matthias Engel
- Pharmaceutical
and Medicinal Chemistry, Saarland University, Campus C2.3, D-66123 Saarbrücken, Germany
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Gonçalves V, Henriques A, Pereira J, Neves Costa A, Moyer MP, Moita LF, Gama-Carvalho M, Matos P, Jordan P. Phosphorylation of SRSF1 by SRPK1 regulates alternative splicing of tumor-related Rac1b in colorectal cells. RNA (NEW YORK, N.Y.) 2014; 20:474-82. [PMID: 24550521 PMCID: PMC3964909 DOI: 10.1261/rna.041376.113] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/07/2014] [Indexed: 05/28/2023]
Abstract
The premessenger RNA of the majority of human genes can generate various transcripts through alternative splicing, and different tissues or disease states show specific patterns of splicing variants. These patterns depend on the relative concentrations of the splicing factors present in the cell nucleus, either as a consequence of their expression levels or of post-translational modifications, such as protein phosphorylation, which are determined by signal transduction pathways. Here, we analyzed the contribution of protein kinases to the regulation of alternative splicing variant Rac1b that is overexpressed in certain tumor types. In colorectal cells, we found that depletion of AKT2, AKT3, GSK3β, and SRPK1 significantly decreased endogenous Rac1b levels. Although knockdown of AKT2 and AKT3 affected only Rac1b protein levels suggesting a post-splicing effect, the depletion of GSK3β or SRPK1 decreased Rac1b alternative splicing, an effect mediated through changes in splicing factor SRSF1. In particular, the knockdown of SRPK1 or inhibition of its catalytic activity reduced phosphorylation and subsequent translocation of SRSF1 to the nucleus, limiting its availability to promote the inclusion of alternative exon 3b into the Rac1 pre-mRNA. Altogether, the data identify SRSF1 as a prime regulator of Rac1b expression in colorectal cells and provide further mechanistic insight into how the regulation of alternative splicing events by protein kinases can contribute to sustain tumor cell survival.
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Affiliation(s)
- Vânia Gonçalves
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Andreia Henriques
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Joana Pereira
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Ana Neves Costa
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | | | - Luís Ferreira Moita
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | - Margarida Gama-Carvalho
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
- Department of Chemistry and Biochemistry, Faculty of Sciences, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Paulo Matos
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
| | - Peter Jordan
- Department of Human Genetics, National Health Institute Dr. Ricardo Jorge, 1649-016 Lisbon, Portugal
- BioFIG–Centre for Biodiversity, Functional and Integrative Genomics, University of Lisbon, 1749-016 Lisbon, Portugal
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Kaminska D, Hämäläinen M, Cederberg H, Käkelä P, Venesmaa S, Miettinen P, Ilves I, Herzig KH, Kolehmainen M, Karhunen L, Kuusisto J, Gylling H, Laakso M, Pihlajamäki J. Adipose tissue INSR splicing in humans associates with fasting insulin level and is regulated by weight loss. Diabetologia 2014; 57:347-51. [PMID: 24196191 DOI: 10.1007/s00125-013-3097-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 10/09/2013] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS The insulin receptor (INSR) has two protein isoforms based on alternative splicing of exon 11. INSR-A promotes cell growth whereas INSR-B predominantly regulates glucose homeostasis. In this study we investigated whether weight loss regulates INSR alternative splicing and the expression of splicing factors in adipose tissue. METHODS To determine the relative ratio of the INSR splice variants, we implemented the PCR-capillary electrophoresis method with adipose tissue samples from two weight-loss-intervention studies, the Kuopio Obesity Surgery study (KOBS, n = 108) and a very low calorie diet (VLCD) intervention (n = 32), and from the population-based Metabolic Syndrome in Men study (METSIM, n = 49). RESULTS Expression of INSR-B mRNA variant increased in response to weight loss induced by both bariatric surgery (p = 1 × 10(-5)) and the VLCD (p = 1 × 10(-4)). The adipose tissue expression of INSR-B correlated negatively with fasting insulin levels in the pooled data of the three studies (p = 3 × 10(-22)). Finally, expression of several splicing factors correlated negatively with the expression of the INSR-B variant. The strongest correlation was with HNRNPA1 (p = 1 × 10(-5)), a known regulator of INSR exon 11 splicing. CONCLUSIONS/INTERPRETATION INSR splicing is regulated by weight loss and associates with insulin levels. The effect of weight loss on INSR splicing could be mediated by changes in the expression of splicing factors.
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Affiliation(s)
- Dorota Kaminska
- Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Yliopistonranta 1, P.O. Box 1627, 70210, Kuopio, Finland
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41
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Diehl N, Schaal H. Make yourself at home: viral hijacking of the PI3K/Akt signaling pathway. Viruses 2013; 5:3192-212. [PMID: 24351799 PMCID: PMC3967167 DOI: 10.3390/v5123192] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 12/03/2013] [Accepted: 12/05/2013] [Indexed: 01/04/2023] Open
Abstract
As viruses do not possess genes encoding for proteins required for translation, energy metabolism or membrane biosynthesis, they are classified as obligatory intracellular parasites that depend on a host cell to replicate. This genome limitation forces them to gain control over cellular processes to ensure their successful propagation. A diverse spectrum of virally encoded proteins tackling a broad spectrum of cellular pathways during most steps of the viral life cycle ranging from the host cell entry to viral protein translation has evolved. Since the host cell PI3K/Akt signaling pathway plays a critical regulatory role in many cellular processes including RNA processing, translation, autophagy and apoptosis, many viruses, in widely varying ways, target it. This review focuses on a number of remarkable examples of viral strategies, which exploit the PI3K/Akt signaling pathway for effective viral replication.
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Affiliation(s)
| | - Heiner Schaal
- Universitätsklinikum Düsseldorf, Institut für Virologie, Universitätsstraße 1, Düsseldorf 40225, Germany.
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42
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Ellis BC, Graham LD, Molloy PL. CRNDE, a long non-coding RNA responsive to insulin/IGF signaling, regulates genes involved in central metabolism. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:372-86. [PMID: 24184209 DOI: 10.1016/j.bbamcr.2013.10.016] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 10/04/2013] [Accepted: 10/21/2013] [Indexed: 12/18/2022]
Abstract
Colorectal neoplasia differentially expressed (CRNDE) is a novel gene that is activated early in colorectal cancer but whose regulation and functions are unknown. CRNDE transcripts are recognized as long non-coding RNAs (lncRNAs), which potentially interact with chromatin-modifying complexes to regulate gene expression via epigenetic changes. Complex alternative splicing results in numerous transcripts from this gene, and we have identified novel transcripts containing a highly-conserved sequence within intron 4 ("gVC-In4"). In colorectal cancer cells, we demonstrate that treatment with insulin and insulin-like growth factors (IGF) repressed CRNDE nuclear transcripts, including those encompassing gVC-In4. These repressive effects were negated by use of inhibitors against either the PI3K/Akt/mTOR pathway or Raf/MAPK pathway, suggesting CRNDE is a downstream target of both signaling cascades. Expression array analyses revealed that siRNA-mediated knockdown of gVC-In4 transcripts affected the expression of many genes, which showed correlation with insulin/IGF signaling pathway components and responses, including glucose and lipid metabolism. Some of the genes are identical to those affected by insulin treatment in the same cell line. The results suggest that CRNDE expression promotes the metabolic changes by which cancer cells switch to aerobic glycolysis (Warburg effect). This is the first report of a lncRNA regulated by insulin/IGFs, and our findings indicate a role for CRNDE nuclear transcripts in regulating cellular metabolism which may correlate with their upregulation in colorectal cancer.
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Affiliation(s)
- Blake C Ellis
- CSIRO Animal, Food and Health Sciences, Preventative Health Flagship, Commonwealth Scientific and Industrial Research Organization, Sydney, NSW 2113 Australia.
| | - Lloyd D Graham
- CSIRO Animal, Food and Health Sciences, Preventative Health Flagship, Commonwealth Scientific and Industrial Research Organization, Sydney, NSW 2113 Australia.
| | - Peter L Molloy
- CSIRO Animal, Food and Health Sciences, Preventative Health Flagship, Commonwealth Scientific and Industrial Research Organization, Sydney, NSW 2113 Australia.
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43
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Phosphorylation-mediated regulation of alternative splicing in cancer. Int J Cell Biol 2013; 2013:151839. [PMID: 24069033 PMCID: PMC3771450 DOI: 10.1155/2013/151839] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/26/2013] [Indexed: 12/12/2022] Open
Abstract
Alternative splicing (AS) is one of the key processes involved in the regulation of gene expression in eukaryotic cells. AS catalyzes the removal of intronic sequences and the joining of selected exons, thus ensuring the correct processing of the primary transcript into the mature mRNA. The combinatorial nature of AS allows a great expansion of the genome coding potential, as multiple splice-variants encoding for different proteins may arise from a single gene. Splicing is mediated by a large macromolecular complex, the spliceosome, whose activity needs a fine regulation exerted by cis-acting RNA sequence elements and trans-acting RNA binding proteins (RBP). The activity of both core spliceosomal components and accessory splicing factors is modulated by their reversible phosphorylation. The kinases and phosphatases involved in these posttranslational modifications significantly contribute to AS regulation and to its integration in the complex regulative network that controls gene expression in eukaryotic cells. Herein, we will review the major canonical and noncanonical splicing factor kinases and phosphatases, focusing on those whose activity has been implicated in the aberrant splicing events that characterize neoplastic transformation.
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44
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Kaminska D, Pihlajamäki J. Regulation of alternative splicing in obesity and weight loss. Adipocyte 2013; 2:143-7. [PMID: 23991360 PMCID: PMC3756102 DOI: 10.4161/adip.24751] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 04/16/2013] [Accepted: 04/19/2013] [Indexed: 01/04/2023] Open
Abstract
Alternative splicing (AS) is a mechanism by which multiple mRNA transcripts are generated from a single gene. According to recent reports approximately 95–100% of human multi-exon genes undergo AS. This increases the amount of functionally different protein isoforms, and in some cases leads to metabolic diseases. Herein we provide a brief overview of the basic aspects of splicing regulation in obesity and insulin resistance with specific examples. In addition, we review our recent findings demonstrating that weight loss regulates AS of TCF7L2 gene in both liver and adipose tissue, and that this splicing associates with changes in fatty acid and glucose metabolism. Future studies using global analysis of transcript variants and splicing regulators are needed for exploring the association of AS with metabolic alterations in obesity and type 2 diabetes (T2D). Understanding of the molecular mechanisms behind the aberrantly spliced transcripts may also provide opportunities for new diagnostic approaches.
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45
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Coombs TC, Tanega C, Shen M, Wang JL, Auld DS, Gerritz SW, Schoenen FJ, Thomas CJ, Aubé J. Small-molecule pyrimidine inhibitors of the cdc2-like (Clk) and dual specificity tyrosine phosphorylation-regulated (Dyrk) kinases: development of chemical probe ML315. Bioorg Med Chem Lett 2013; 23:3654-61. [PMID: 23642479 PMCID: PMC3664191 DOI: 10.1016/j.bmcl.2013.02.096] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 02/21/2013] [Indexed: 01/17/2023]
Abstract
Substituted pyrimidine inhibitors of the Clk and Dyrk kinases have been developed, exploring structure-activity relationships around four different chemotypes. The most potent compounds have low-nanomolar inhibitory activity against Clk1, Clk2, Clk4, Dyrk1A and Dyrk1B. Kinome scans with 442 kinases using agents representing three of the chemotypes show these inhibitors to be highly selective for the Clk and Dyrk families. Further off-target pharmacological evaluation with ML315, the most selective agent, supports this conclusion.
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Affiliation(s)
- Thomas C Coombs
- University of Kansas Specialized Chemistry Center, University of Kansas, Lawrence, KS 66047, USA
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46
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Regulation of splicing by SR proteins and SR protein-specific kinases. Chromosoma 2013; 122:191-207. [PMID: 23525660 DOI: 10.1007/s00412-013-0407-z] [Citation(s) in RCA: 306] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 12/21/2022]
Abstract
Genomic sequencing reveals similar but limited numbers of protein-coding genes in different genomes, which begs the question of how organismal diversities are generated. Alternative pre-mRNA splicing, a widespread phenomenon in higher eukaryotic genomes, is thought to provide a mechanism to increase the complexity of the proteome and introduce additional layers for regulating gene expression in different cell types and during development. Among a large number of factors implicated in the splicing regulation are the SR protein family of splicing factors and SR protein-specific kinases. Here, we summarize the rules for SR proteins to function as splicing regulators, which depend on where they bind in exons versus intronic regions, on alternative exons versus flanking competing exons, and on cooperative as well as competitive binding between different SR protein family members on many of those locations. We review the importance of cycles of SR protein phosphorylation/dephosphorylation in the splicing reaction with emphasis on the recent molecular insight into the role of SR protein phosphorylation in early steps of spliceosome assembly. Finally, we highlight recent discoveries of SR protein-specific kinases in transducing growth signals to regulate alternative splicing in the nucleus and the connection of both SR proteins and SR protein kinases to human diseases, particularly cancer.
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47
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Breig O, Baklouti F. Proteasome-mediated proteolysis of SRSF5 splicing factor intriguingly co-occurs with SRSF5 mRNA upregulation during late erythroid differentiation. PLoS One 2013; 8:e59137. [PMID: 23536862 PMCID: PMC3594168 DOI: 10.1371/journal.pone.0059137] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 02/13/2013] [Indexed: 01/08/2023] Open
Abstract
SR proteins exhibit diverse functions ranging from their role in constitutive and alternative splicing, to virtually all aspects of mRNA metabolism. These findings have attracted growing interest in deciphering the regulatory mechanisms that control the tissue-specific expression of these SR proteins. In this study, we show that SRSF5 protein decreases drastically during erythroid cell differentiation, contrasting with a concomitant upregulation of SRSF5 mRNA level. Proteasome chemical inhibition provided strong evidence that endogenous SRSF5 protein, as well as protein deriving from stably transfected SRSF5 cDNA, are both targeted to proteolysis as the cells undergo terminal differentiation. Consistently, functional experiments show that overexpression of SRSF5 enhances a specific endogenous pre-mRNA splicing event in proliferating cells, but not in differentiating cells, due to proteasome-mediated targeting of both endogenous and transfection-derived SRSF5. Further investigation of the relationship between SRSF5 structure and its post-translation regulation and function, suggested that the RNA recognition motifs of SRSF5 are sufficient to activate pre-mRNA splicing, whereas proteasome-mediated proteolysis of SRSF5 requires the presence of the C-terminal RS domain of the protein. Phosphorylation of SR proteins is a key post-translation regulation that promotes their activity and subcellular availability. We here show that inhibition of the CDC2-like kinase (CLK) family and mutation of the AKT phosphorylation site Ser86 on SRSF5, have no effect on SRSF5 stability. We reasoned that at least AKT and CLK signaling pathways are not involved in proteasome-induced turnover of SRSF5 during late erythroid development.
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Affiliation(s)
- Osman Breig
- "mRNA Metabolism in Normal and Pathological Cells"; Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR, Université Lyon 1, Villeurbanne, France
| | - Faouzi Baklouti
- "mRNA Metabolism in Normal and Pathological Cells"; Centre de Génétique et de Physiologie Moléculaire et Cellulaire, CNRS UMR, Université Lyon 1, Villeurbanne, France
- * E-mail:
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48
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Li P, Carter G, Romero J, Gower KM, Watson J, Patel NA, Cooper DR. Clk/STY (cdc2-like kinase 1) and Akt regulate alternative splicing and adipogenesis in 3T3-L1 pre-adipocytes. PLoS One 2013; 8:e53268. [PMID: 23308182 PMCID: PMC3537621 DOI: 10.1371/journal.pone.0053268] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 11/28/2012] [Indexed: 12/21/2022] Open
Abstract
The development of adipocytes from their progenitor cells requires the action of growth factors signaling to transcription factors to induce the expression of adipogenic proteins leading to the accumulation of lipid droplets, induction of glucose transport, and secretion of adipokines signaling metabolic events throughout the body. Murine 3T3-L1 pre-adipocytes sequentially express all the proteins necessary to become mature adipocytes throughout an 8–10 day process initiated by a cocktail of hormones. We examined the role of Clk/STY or Clk1, a cdc2-like kinase, in adipogenesis since it is known to be regulated by Akt, a pivotal kinase in development. Inhibition of Clk1 by a specific inhibitor, TG003, blocked alternative splicing of PKCβII and expression of PPARγ1 and PPARγ2. SiRNA depletion of Clk1 resulted in early expression of PKCβII and sustained PKCβI expression. Since Clk1 is a preferred Akt substrate, required for phosphorylation of splicing factors, mutation of Clk1 Akt phosphorylation sites was undertaken. Akt sites on Clk1 are in the serine/arginine-rich domain and not the kinase domain. Mutation of single and multiple sites resulted in dysregulation of PKCβII, PKCβI, and PPARγ1&2 expression. Additionally, adipogenesis was blocked as assessed by Oil Red O staining, adiponectin, and Glut1 and 4 expression. Immunofluorescence microscopy revealed that Clk1 triple mutant cDNA, transfected into pre-adipocytes, resulted in excluding SRp40 (SFSR6) from co-localizing to the nucleus with PFS, a perispeckle specific protein. This study demonstrates the role of Akt and Clk1 kinases in the early differentiation of 3T3-L1 cells to adipocytes.
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Affiliation(s)
- Pengfei Li
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Gay Carter
- Research Service, J.A. Haley Veterans Hospital, Tampa, Florida, United States of America
| | - Jacqueline Romero
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - Kathryn M. Gower
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
| | - James Watson
- Research Service, J.A. Haley Veterans Hospital, Tampa, Florida, United States of America
| | - Niketa A. Patel
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
- Research Service, J.A. Haley Veterans Hospital, Tampa, Florida, United States of America
| | - Denise R. Cooper
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America
- Research Service, J.A. Haley Veterans Hospital, Tampa, Florida, United States of America
- * E-mail:
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49
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Walsh CM, Suchanek AL, Cyphert TJ, Kohan AB, Szeszel-Fedorowicz W, Salati LM. Serine arginine splicing factor 3 is involved in enhanced splicing of glucose-6-phosphate dehydrogenase RNA in response to nutrients and hormones in liver. J Biol Chem 2012; 288:2816-28. [PMID: 23233666 DOI: 10.1074/jbc.m112.410803] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Expression of G6PD is controlled by changes in the degree of splicing of the G6PD mRNA in response to nutrients in the diet. This regulation involves an exonic splicing enhancer (ESE) in exon 12 of the mRNA. Using the G6PD model, we demonstrate that nutrients and hormones control the activity of serine-arginine-rich (SR) proteins, a family of splicing co-activators, and thereby regulate the splicing of G6PD mRNA. In primary rat hepatocyte cultures, insulin increased the amount of phosphorylated SR proteins, and this effect was counteracted by arachidonic acid. The results of RNA affinity analysis with nuclear extracts from intact liver demonstrated that the SR splicing factor proteins SRSF3 and SRSF4 bound to the G6PD ESE. Consequently, siRNA-mediated depletion of SRSF3, but not SRSF4, in liver cells inhibited accumulation of both mRNA expressed from a minigene containing exon 12 and the endogenous G6PD mRNA. Consistent with the functional role of SRSF3 in regulating splicing, SRSF3 was observed to bind to the ESE in both intact cells and in animals using RNA immunoprecipitation analysis. Furthermore, refeeding significantly increased the binding of SRSF3 coincident with increased splicing and expression of G6PD. Together, these data establish that nutritional regulation of SRSF3 activity is involved in the differential splicing of the G6PD transcript in response to nutrients. Nutritional regulation of other SR proteins presents a regulatory mechanism that could cause widespread changes in mRNA splicing. Nutrients are therefore novel regulators of mRNA splicing.
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Affiliation(s)
- Callee M Walsh
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia 26506, USA
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50
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Tang Y, Horikawa I, Ajiro M, Robles AI, Fujita K, Mondal AM, Stauffer JK, Zheng ZM, Harris CC. Downregulation of splicing factor SRSF3 induces p53β, an alternatively spliced isoform of p53 that promotes cellular senescence. Oncogene 2012; 32:2792-8. [PMID: 22777358 DOI: 10.1038/onc.2012.288] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Most human pre-mRNA transcripts are alternatively spliced, but the significance and fine-tuning of alternative splicing in different biological processes is only starting to be understood. SRSF3 (SRp20) is a member of a highly conserved family of splicing factors that have critical roles in key biological processes, including tumor progression. Here, we show that SRSF3 regulates cellular senescence, a p53-mediated process to suppress tumorigenesis, through TP53 alternative splicing. Downregulation of SRSF3 was observed in normal human fibroblasts undergoing replicative senescence, and was associated with the upregulation of p53β, an alternatively spliced isoform of p53 that promotes p53-mediated senescence. Knockdown of SRSF3 by short interfering RNA (siRNA) in early-passage fibroblasts induced senescence, which was associated with elevated expression of p53β at mRNA and protein levels. Knockdown of p53 partially rescued SRSF3-knockdown-induced senescence, suggesting that SRSF3 acts on p53-mediated cellular senescence. RNA pulldown assays demonstrated that SRSF3 binds to an alternatively spliced exon uniquely included in p53β mRNA through the consensus SRSF3-binding sequences. RNA crosslinking and immunoprecipitation assays (CLIP) also showed that SRSF3 in vivo binds to endogenous p53 pre-mRNA at the region containing the p53β-unique exon. Splicing assays using a transfected TP53 minigene in combination with siRNA knockdown of SRSF3 showed that SRSF3 functions to inhibit the inclusion of the p53β-unique exon in splicing of p53 pre-mRNA. These data suggest that downregulation of SRSF3 represents an endogenous mechanism for cellular senescence that directly regulates the TP53 alternative splicing to generate p53β. This study uncovers the role for general splicing machinery in tumorigenesis, and suggests that SRSF3 is a direct regulator of p53.
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Affiliation(s)
- Y Tang
- Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4258, USA
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