1
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Beyer ASL, Kaemmerer D, Sänger J, Lupp A. Expression of FAM159B in Humans, Rats, and Mice: A Cross-species Examination. J Histochem Cytochem 2024; 72:467-487. [PMID: 38907656 PMCID: PMC11308193 DOI: 10.1369/00221554241262368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 05/23/2024] [Indexed: 06/24/2024] Open
Abstract
Little is known about the adaptor protein FAM159B. To determine whether FAM159B expression findings in rats or mice can be extrapolated to humans, we compared FAM159B expression in healthy tissue samples from all three species using immunohistochemistry. Despite variations in expression intensity, similar FAM159B expression patterns were observed in most organs across species. The most prominent species difference was noted in pancreatic islets; while FAM159B expression was limited to single cells on the outer edges in mice and rats, it was detectable across entire islets in humans. Double-labeling immunohistochemistry revealed partial overlap of FAM159B expression with that of insulin, glucagon, and somatostatin in human islets. By contrast, FAM159B showed complete colocalization with only somatostatin in rats and mice. An additional analysis of FAM159B expression in lean and obese Zucker rats revealed larger islet areas due to increased β-cell mass in obese rats, which was accompanied by a smaller percentage of FAM159B-positive δ-cells per islet area. Beyond the known differences in islet architecture across species, our results point to larger dissimilarities in blood glucose regulation between rodents and humans than generally assumed. Moreover, findings regarding FAM159B expression (and function) cannot be directly transferred between rodents and humans.
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Affiliation(s)
| | - Daniel Kaemmerer
- Department of General and Visceral Surgery, Zentralklinik Bad Berka, Bad Berka, Germany
| | - Jörg Sänger
- Laboratory of Pathology and Cytology Bad Berka, Bad Berka, Germany
| | - Amelie Lupp
- Institute of Pharmacology and Toxicology, Jena University Hospital, Jena, Germany
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2
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Li J, Huang G. Insulin receptor alternative splicing in breast and prostate cancer. Cancer Cell Int 2024; 24:62. [PMID: 38331804 PMCID: PMC10851471 DOI: 10.1186/s12935-024-03252-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 02/01/2024] [Indexed: 02/10/2024] Open
Abstract
Cancer etiology represents an intricate, multifactorial orchestration where metabolically associated insulin-like growth factors (IGFs) and insulin foster cellular proliferation and growth throughout tumorigenesis. The insulin receptor (IR) exhibits two splice variants arising from alternative mRNA processing, namely IR-A, and IR-B, with remarkable distribution and biological effects disparities. This insightful review elucidates the structural intricacies, widespread distribution, and functional significance of IR-A and IR-B. Additionally, it explores the regulatory mechanisms governing alternative splicing processes, intricate signal transduction pathways, and the intricate association linking IR-A and IR-B splicing variants to breast and prostate cancer tumorigenesis. Breast cancer and prostate cancer are the most common malignant tumors with the highest incidence rates among women and men, respectively. These findings provide a promising theoretical framework for advancing preventive strategies, diagnostic modalities, and therapeutic interventions targeting breast and prostate cancer.
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Affiliation(s)
- Jinyu Li
- Department of Medical Oncology, The Second Hospital of Dalian Medical University, No. 467 Zhongshan Road, Shahekou District, Dalian, 116023, Liaoning, China
| | - Gena Huang
- Department of Medical Oncology, The Second Hospital of Dalian Medical University, No. 467 Zhongshan Road, Shahekou District, Dalian, 116023, Liaoning, China.
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3
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Nowzari ZR, Hale M, Ellis J, Biaesch S, Vangaveti S, Reddy K, Chen AA, Berglund JA. Mutation of two intronic nucleotides alters RNA structure and dynamics inhibiting MBNL1 and RBFOX1 regulated splicing of the Insulin Receptor. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.08.574689. [PMID: 38260517 PMCID: PMC10802415 DOI: 10.1101/2024.01.08.574689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Alternative splicing (AS) of Exon 11 of the Insulin Receptor ( INSR ) is highly regulated and disrupted in several human disorders. To better understand INSR exon 11 AS regulation, splicing activity of an INSR exon 11 minigene reporter was measured across a gradient of the AS regulator muscleblind-like 1 protein (MBNL1). The RNA-binding protein Fox-1 (RBFOX1) was added to determine its impact on MBNL1-regulated splicing. The role of the RBFOX1 UGCAUG binding site within intron 11 was assessed across the MBNL1 gradient. Mutating the UGCAUG motif inhibited RBFOX1 regulation of exon 11 and had the unexpected effect of reducing MBNL1 regulation of this exon. Molecular dynamics simulations showed that exon 11 and the adjacent RNA adopts a dynamically stable conformation. Mutation of the RBFOX1 binding site altered RNA structure and dynamics, while a mutation that created an optimal MBNL1 binding site at the RBFOX1 site shifted the RNA back to wild type. An antisense oligonucleotide (ASO) was used to confirm the structure in this region of the pre-mRNA. This example of intronic mutations shifting pre-mRNA structure and dynamics to modulate splicing suggests RNA structure and dynamics should be taken into consideration for AS regulation and therapeutic interventions targeting pre-mRNA.
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4
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Galal MA, Alouch SS, Alsultan BS, Dahman H, Alyabis NA, Alammar SA, Aljada A. Insulin Receptor Isoforms and Insulin Growth Factor-like Receptors: Implications in Cell Signaling, Carcinogenesis, and Chemoresistance. Int J Mol Sci 2023; 24:15006. [PMID: 37834454 PMCID: PMC10573852 DOI: 10.3390/ijms241915006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 09/22/2023] [Accepted: 09/26/2023] [Indexed: 10/15/2023] Open
Abstract
This comprehensive review thoroughly explores the intricate involvement of insulin receptor (IR) isoforms and insulin-like growth factor receptors (IGFRs) in the context of the insulin and insulin-like growth factor (IGF) signaling (IIS) pathway. This elaborate system encompasses ligands, receptors, and binding proteins, giving rise to a wide array of functions, including aspects such as carcinogenesis and chemoresistance. Detailed genetic analysis of IR and IGFR structures highlights their distinct isoforms, which arise from alternative splicing and exhibit diverse affinities for ligands. Notably, the overexpression of the IR-A isoform is linked to cancer stemness, tumor development, and resistance to targeted therapies. Similarly, elevated IGFR expression accelerates tumor progression and fosters chemoresistance. The review underscores the intricate interplay between IRs and IGFRs, contributing to resistance against anti-IGFR drugs. Consequently, the dual targeting of both receptors could present a more effective strategy for surmounting chemoresistance. To conclude, this review brings to light the pivotal roles played by IRs and IGFRs in cellular signaling, carcinogenesis, and therapy resistance. By precisely modulating these receptors and their complex signaling pathways, the potential emerges for developing enhanced anti-cancer interventions, ultimately leading to improved patient outcomes.
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Affiliation(s)
- Mariam Ahmed Galal
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
- Department of Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
| | - Samhar Samer Alouch
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Buthainah Saad Alsultan
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Huda Dahman
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Nouf Abdullah Alyabis
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Sarah Ammar Alammar
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
| | - Ahmad Aljada
- Department of Biochemistry and Molecular Medicine, College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia
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5
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Grande V, Hathazi D, O'Connor E, Marteau T, Schara-Schmidt U, Hentschel A, Gourdon G, Nikolenko N, Lochmüller H, Roos A. Dysregulation of GSK3β-Target Proteins in Skin Fibroblasts of Myotonic Dystrophy Type 1 (DM1) Patients. J Neuromuscul Dis 2021; 8:603-619. [PMID: 33682722 DOI: 10.3233/jnd-200558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is the most common monogenetic muscular disorder of adulthood. This multisystemic disease is caused by CTG repeat expansion in the 3'-untranslated region of the DM1 protein kinase gene called DMPK. DMPK encodes a myosin kinase expressed in skeletal muscle cells and other cellular populations such as smooth muscle cells, neurons and fibroblasts. The resultant expanded (CUG)n RNA transcripts sequester RNA binding factors leading to ubiquitous and persistent splicing deregulation. The accumulation of mutant CUG repeats is linked to increased activity of glycogen synthase kinase 3 beta (GSK3β), a highly conserved and ubiquitous serine/threonine kinase with functions in pathways regulating inflammation, metabolism, oncogenesis, neurogenesis and myogenesis. As GSK3β-inhibition ameliorates defects in myogenesis, muscle strength and myotonia in a DM1 mouse model, this kinase represents a key player of DM1 pathobiochemistry and constitutes a promising therapeutic target. To better characterise DM1 patients, and monitor treatment responses, we aimed to define a set of robust disease and severity markers linked to GSK3βby unbiased proteomic profiling utilizing fibroblasts derived from DM1 patients with low (80- 150) and high (2600- 3600) CTG-repeats. Apart from GSK3β increase, we identified dysregulation of nine proteins (CAPN1, CTNNB1, CTPS1, DNMT1, HDAC2, HNRNPH3, MAP2K2, NR3C1, VDAC2) modulated by GSK3β. In silico-based expression studies confirmed expression in neuronal and skeletal muscle cells and revealed a relatively elevated abundance in fibroblasts. The potential impact of each marker in the myopathology of DM1 is discussed based on respective function to inform potential uses as severity markers or for monitoring GSK3β inhibitor treatment responses.
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Affiliation(s)
- Valentina Grande
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Denisa Hathazi
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany.,Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Emily O'Connor
- Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
| | - Theo Marteau
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Ulrike Schara-Schmidt
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany
| | - Andreas Hentschel
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany
| | - Genevieve Gourdon
- Centre de Recherche en Myologie, Association Institut de Myologie, Sorbonne Université, Inserm UMR 974, Paris, France
| | - Nikoletta Nikolenko
- National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, UK
| | - Hanns Lochmüller
- Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada.,Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON, Canada.,Department of Neuropediatrics and Muscle Disorders, Faculty of Medicine, Medical Center - University of Freiburg, Freiburg, Germany.,Centro Nacional de AnálisisGenómico, Center for Genomic Regulation (CNAG-CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain
| | - Andreas Roos
- Department of Neuropediatrics, University Hospital Essen, Duisburg-Essen University, Germany.,Childrens Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, ON, Canada
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6
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Louis JM, Agarwal A, Aduri R, Talukdar I. Global analysis of RNA-protein interactions in TNF-α induced alternative splicing in metabolic disorders. FEBS Lett 2021; 595:476-490. [PMID: 33417721 DOI: 10.1002/1873-3468.14029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 11/26/2020] [Accepted: 12/10/2020] [Indexed: 12/27/2022]
Abstract
In this report, using the database of RNA-binding protein specificities (RBPDB) and our previously published RNA-seq data, we analyzed the interactions between RNA and RNA-binding proteins to decipher the role of alternative splicing in metabolic disorders induced by TNF-α. We identified 13 395 unique RNA-RBP interactions, including 385 unique RNA motifs and 35 RBPs, some of which (including MBNL-1 and 3, ZFP36, ZRANB2, and SNRPA) are transcriptionally regulated by TNF-α. In addition to some previously reported RBPs, such as RBMX and HuR/ELAVL1, we found a few novel RBPs, such as ZRANB2 and SNRPA, to be involved in the regulation of metabolic syndrome-associated genes that contain an enrichment of tetrameric RNA sequences (AUUU). Taken together, this study paves the way for novel RNA-protein interaction-based therapeutics for treating metabolic syndromes.
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Affiliation(s)
- Jiss Maria Louis
- Department of Biological Sciences, BITS Pilani, Zuarinagar, India
| | - Arjun Agarwal
- Department of Computer Science, BITS Pilani, Zuarinagar, India
| | - Raviprasad Aduri
- Department of Biological Sciences, BITS Pilani, Zuarinagar, India
| | - Indrani Talukdar
- Department of Biological Sciences, BITS Pilani, Zuarinagar, India
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7
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Scalia P, Giordano A, Martini C, Williams SJ. Isoform- and Paralog-Switching in IR-Signaling: When Diabetes Opens the Gates to Cancer. Biomolecules 2020; 10:biom10121617. [PMID: 33266015 PMCID: PMC7761347 DOI: 10.3390/biom10121617] [Citation(s) in RCA: 8] [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: 09/28/2020] [Revised: 11/21/2020] [Accepted: 11/23/2020] [Indexed: 12/12/2022] Open
Abstract
Insulin receptor (IR) and IR-related signaling defects have been shown to trigger insulin-resistance in insulin-dependent cells and ultimately to give rise to type 2 diabetes in mammalian organisms. IR expression is ubiquitous in mammalian tissues, and its over-expression is also a common finding in cancerous cells. This latter finding has been shown to associate with both a relative and absolute increase in IR isoform-A (IR-A) expression, missing 12 aa in its EC subunit corresponding to exon 11. Since IR-A is a high-affinity transducer of Insulin-like Growth Factor-II (IGF-II) signals, a growth factor is often secreted by cancer cells; such event offers a direct molecular link between IR-A/IR-B increased ratio in insulin resistance states (obesity and type 2 diabetes) and the malignant advantage provided by IGF-II to solid tumors. Nonetheless, recent findings on the biological role of isoforms for cellular signaling components suggest that the preferential expression of IR isoform-A may be part of a wider contextual isoform-expression switch in downstream regulatory factors, potentially enhancing IR-dependent oncogenic effects. The present review focuses on the role of isoform- and paralog-dependent variability in the IR and downstream cellular components playing a potential role in the modulation of the IR-A signaling related to the changes induced by insulin-resistance-linked conditions as well as to their relationship with the benign versus malignant transition in underlying solid tumors.
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Affiliation(s)
- Pierluigi Scalia
- Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, PA 19122, USA; (A.G.); (C.M.); (S.J.W.)
- ISOPROG-Somatolink EPFP Network, Functional Research Unit, Philadelphia, PA 19104, USA and 93100 Caltanissetta, Italy
- Correspondence:
| | - Antonio Giordano
- Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, PA 19122, USA; (A.G.); (C.M.); (S.J.W.)
- Department of Medical Biotechnologies, University of Siena, 52100 Siena, Italy
| | - Caroline Martini
- Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, PA 19122, USA; (A.G.); (C.M.); (S.J.W.)
| | - Stephen J. Williams
- Sbarro Institute for Cancer Research and Molecular Medicine, Temple University, Philadelphia, PA 19122, USA; (A.G.); (C.M.); (S.J.W.)
- ISOPROG-Somatolink EPFP Network, Functional Research Unit, Philadelphia, PA 19104, USA and 93100 Caltanissetta, Italy
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8
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Abstract
Elevated circulating insulin levels are frequently observed in the setting of obesity and early type 2 diabetes, as a result of insensitivity of metabolic tissues to the effects of insulin. Higher levels of circulating insulin have been associated with increased cancer risk and progression in epidemiology studies. Elevated circulating insulin is believed to be a major factor linking obesity, diabetes and cancer. With the development of targeted cancer therapies, insulin signalling has emerged as a mechanism of therapeutic resistance. Although metabolic tissues become insensitive to insulin in the setting of obesity, a number of mechanisms allow cancer cells to maintain their ability to respond to insulin. Significant progress has been made in the past decade in understanding the insulin receptor and its signalling pathways in cancer, and a number of lessons have been learnt from therapeutic failures. These discoveries have led to numerous clinical trials that have aimed to reduce the levels of circulating insulin and to abrogate insulin signalling in cancer cells. With the rising prevalence of obesity and diabetes worldwide, and the realization that hyperinsulinaemia may contribute to therapeutic failures, it is essential to understand how insulin and insulin receptor signalling promote cancer progression.
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Affiliation(s)
- Emily J Gallagher
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- The Tisch Cancer Institute at Mount Sinai, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Derek LeRoith
- Division of Endocrinology, Diabetes and Bone Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- The Tisch Cancer Institute at Mount Sinai, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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9
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Huang G, Song C, Wang N, Qin T, Sui S, Obr A, Zeng L, Wood TL, Leroith D, Li M, Wu Y. RNA-binding protein CUGBP1 controls the differential INSR splicing in molecular subtypes of breast cancer cells and affects cell aggressiveness. Carcinogenesis 2020; 41:1294-1305. [PMID: 31958132 PMCID: PMC7513956 DOI: 10.1093/carcin/bgz141] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/18/2019] [Accepted: 12/11/2019] [Indexed: 12/15/2022] Open
Abstract
The insulin receptor gene (INSR) undergoes alternative splicing to give rise to two functionally related, but also distinct, isoforms IR-A and IR-B, which dictate proliferative and metabolic regulations, respectively. Previous studies identified the RNA-binding protein CUGBP1 as a key regulator of INSR splicing. In this study, we show that the differential splicing of INSR occurs more frequently in breast cancer than in non-tumor breast tissues. In breast cancer cell lines, the IR-A:IR-B ratio varies in different molecular subtypes, knockdown or overexpression of CUGBP1 gene in breast cancer cells altered IR-A:IR-B ratio through modulation of IR-A expression, thereby reversed or enhanced the insulin-induced oncogenic behavior of breast cancer cells, respectively. Our data revealed the predominant mitogenic role of IR-A isoform in breast cancer and depicted a novel interplay between INSR and CUGBP1, implicating CUGBP1 and IR-A isoform as the potential therapeutic targets and biomarkers for breast cancer.
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Affiliation(s)
- Gena Huang
- Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian, Liaoning, China
- Department of Breast Oncology, The Second Hospital of Dalian Medical University, Dalian, Liaoning, China
- National Center of Genetically Engineered Animal Models for International Research, Dalian Medical University, Dalian, Liaoning, China
- Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning, China
| | - Chen Song
- Department of Breast Oncology, The Second Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Ning Wang
- Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian, Liaoning, China
- National Center of Genetically Engineered Animal Models for International Research, Dalian Medical University, Dalian, Liaoning, China
- Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning, China
| | - Tao Qin
- Department of Pathology, Dalian Medical University, Dalian, Liaoning, China
| | - Silei Sui
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, Liaoning, China
| | - Alison Obr
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Cancer Institute of New Jersey, Newark, NJ, USA
| | - Li Zeng
- Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian, Liaoning, China
- National Center of Genetically Engineered Animal Models for International Research, Dalian Medical University, Dalian, Liaoning, China
| | - Teresa L Wood
- Department of Pharmacology, Physiology and Neuroscience, Rutgers New Jersey Medical School, Cancer Institute of New Jersey, Newark, NJ, USA
| | - Derek Leroith
- Division of Endocrinology, Diabetes and Bone Disease, Department of Medicine, Icahn Mount Sinai School of Medicine, New York, NY, USA
| | - Man Li
- Department of Breast Oncology, The Second Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Yingjie Wu
- Institute for Genome Engineered Animal Models of Human Diseases, Dalian Medical University, Dalian, Liaoning, China
- National Center of Genetically Engineered Animal Models for International Research, Dalian Medical University, Dalian, Liaoning, China
- Liaoning Provence Key Lab of Genome Engineered Animal Models, Dalian Medical University, Dalian, Liaoning, China
- Division of Endocrinology, Diabetes and Bone Disease, Department of Medicine, Icahn Mount Sinai School of Medicine, New York, NY, USA
- College of Integrative Medicine, Dalian Medical University, Dalian, Liaoning, China
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10
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Lin YC, Lu YH, Lee YC, Hung CS, Lin JC. Altered expressions and splicing profiles of Acin1 transcripts differentially modulate brown adipogenesis through an alternative splicing mechanism. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1863:194601. [PMID: 32629174 DOI: 10.1016/j.bbagrm.2020.194601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2020] [Revised: 06/26/2020] [Accepted: 06/28/2020] [Indexed: 10/23/2022]
Abstract
Apoptotic chromatin condensation inducer in the nucleus (also referred as Acin1) was first characterized as an RNA-binding protein involved in apoptosis. In later reports, Acin1 was identified as an auxiliary component of the exon junction complex (EJC) which is assembled throughout pre-messenger RNA splicing. In this study, results of whole-transcriptome analyses revealed reduced expressions and reprogrammed splicing profiles of Acin1 transcripts throughout development of brown adipose tissues (BATs) that execute non-shivering thermogenesis in small rodents and infants by consuming lipids. Depletion of endogenous Acin1 isoforms led to activation of brown adipogenic signatures in mouse C3H10T1/2 fibroblasts. Nevertheless, overexpressions of the Acin1-L or Acin1-S isoform exerted discriminative influences on brown adipogenesis and reprogramming of the expression of serine/arginine-rich splicing factor 3 (SRSF3) through an alternative splicing-coupled nonsense-mediated decay mechanism in a sequence-specific manner. Moreover, the Acin1-SRSF3 axis constitutes a regulatory pathway that participates in the brown adipocyte-related splicing network. Taken together, the interplay between accessory EJC components and splicing regulators constitutes an emerging mechanism for differentially manipulating the activity of brown adipogenesis via alternative splicing network.
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Affiliation(s)
- Ying-Chin Lin
- Department of Family Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Family Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Yi-Han Lu
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Yuan-Chii Lee
- Graduate Institute of Biomedical Informatics, Taipei Medical University, Taipei, Taiwan
| | - Ching-Sheng Hung
- PhD Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Department of Laboratory Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Jung-Chun Lin
- School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; PhD Program in Medical Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Pulmonary Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
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11
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Hung CS, Lin JC. Alternatively spliced MBNL1 isoforms exhibit differential influence on enhancing brown adipogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1863:194437. [PMID: 31730826 DOI: 10.1016/j.bbagrm.2019.194437] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 01/15/2023]
Abstract
Browning of white adipocytes (WAs) (also referred as beige cells) was demonstrated to execute thermogenesis by consuming stored lipids as do brown adipocytes (BAs), and this is highly related to metabolic homeostasis. Alternative splicing (AS) constitutes a pivotal mechanism for defining cellular fates and functional specifications. Nevertheless, the impacts of AS regulation on the browning of WAs have not been comprehensively investigated. In this study, we first identified the discriminative expression and splicing profiles of the muscleblind-like 1 (MBNL1) gene in postnatal brown adipose tissues (BATs) compared to those of embryonic BATs. A shift in the MBNL1+ex 5 isoform 7 (MBNL17) to MBNL1-ex 5 isoform 1 (MBNL11) was characterized throughout BAT development or during the in vitro browning of pre-WAs, 3T3-L1 cells. The interplay between MBNL1 and the exonic CCUG motif constitutes an autoregulatory mechanism for excluding MBNL1 exon 5. The simultaneous association of RNA-binding motif protein 4a (RBM4a) with exonic and intronic CU elements collaboratively mediates the skipping of MBNL1 exon 5. Overexpressing the MBNL11 isoform exhibited a more-prominent effect than that of the MBNL17 isoform on programming its own transcripts and beige cell-related splicing events in a CCUG motif-mediated manner. In addition to splicing regulation, overexpression of the MBNL11 and MBNL17 isoforms differentially enhanced beige adipogenic signatures of 3T3-L1 cells. Our findings demonstrated that MBNL1 constitutes an emerging and autoregulatory mechanism involved in development of beige cells.
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Affiliation(s)
- Ching-Sheng Hung
- PhD Program in Medicine Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; Department of Laboratory Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Jung-Chun Lin
- PhD Program in Medicine Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan; School of Medical Laboratory Science and Biotechnology, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan.
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12
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A CTG repeat-selective chemical screen identifies microtubule inhibitors as selective modulators of toxic CUG RNA levels. Proc Natl Acad Sci U S A 2019; 116:20991-21000. [PMID: 31570586 DOI: 10.1073/pnas.1901893116] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A CTG repeat expansion in the DMPK gene is the causative mutation of myotonic dystrophy type 1 (DM1). Transcription of the expanded CTG repeat produces toxic gain-of-function CUG RNA, leading to disease symptoms. A screening platform that targets production or stability of the toxic CUG RNA in a selective manner has the potential to provide new biological and therapeutic insights. A DM1 HeLa cell model was generated that stably expresses a toxic r(CUG)480 and an analogous r(CUG)0 control from DMPK and was used to measure the ratio-metric level of r(CUG)480 versus r(CUG)0. This DM1 HeLa model recapitulates pathogenic hallmarks of DM1, including CUG ribonuclear foci and missplicing of pre-mRNA targets of the muscleblind (MBNL) alternative splicing factors. Repeat-selective screening using this cell line led to the unexpected identification of multiple microtubule inhibitors as hits that selectively reduce r(CUG)480 levels and partially rescue MBNL-dependent missplicing. These results were validated by using the Food and Drug Administration-approved clinical microtubule inhibitor colchicine in DM1 mouse and primary patient cell models. The mechanism of action was found to involve selective reduced transcription of the CTG expansion that we hypothesize to involve the LINC (linker of nucleoskeleton and cytoskeleton) complex. The unanticipated identification of microtubule inhibitors as selective modulators of toxic CUG RNA opens research directions for this form of muscular dystrophy and may shed light on the biology of CTG repeat expansion and inform therapeutic avenues. This approach has the potential to identify modulators of expanded repeat-containing gene expression for over 30 microsatellite expansion disorders.
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13
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Taylor K, Sznajder LJ, Cywoniuk P, Thomas JD, Swanson MS, Sobczak K. MBNL splicing activity depends on RNA binding site structural context. Nucleic Acids Res 2019; 46:9119-9133. [PMID: 29955876 PMCID: PMC6158504 DOI: 10.1093/nar/gky565] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/16/2018] [Indexed: 02/02/2023] Open
Abstract
Muscleblind-like (MBNL) proteins are conserved RNA-binding factors involved in alternative splicing (AS) regulation during development. While AS is controlled by distribution of MBNL paralogs and isoforms, the affinity of these proteins for specific RNA-binding regions and their location within transcripts, it is currently unclear how RNA structure impacts MBNL-mediated AS regulation. Here, we defined the RNA structural determinants affecting MBNL-dependent AS activity using both cellular and biochemical assays. While enhanced inclusion of MBNL-regulated alternative exons is controlled by the arrangement and number of MBNL binding sites within unstructured RNA, when these sites are embedded in a RNA hairpin MBNL binds preferentially to one side of stem region. Surprisingly, binding of MBNL proteins to RNA targets did not entirely correlate with AS efficiency. Moreover, comparison of MBNL proteins revealed structure-dependent competitive behavior between the paralogs. Our results showed that the structure of targeted RNAs is a prevalent component of the mechanism of alternative splicing regulation by MBNLs.
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Affiliation(s)
- Katarzyna Taylor
- Laboratory of Gene Therapy, Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Lukasz J Sznajder
- Center for NeuroGenetics and the Genetics Institute, Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, 2033 Mowry Road, Gainesville, FL 32610, USA
| | - Piotr Cywoniuk
- Laboratory of Gene Therapy, Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - James D Thomas
- Center for NeuroGenetics and the Genetics Institute, Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, 2033 Mowry Road, Gainesville, FL 32610, USA.,Computational Biology Program, Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Maurice S Swanson
- Center for NeuroGenetics and the Genetics Institute, Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, 2033 Mowry Road, Gainesville, FL 32610, USA
| | - Krzysztof Sobczak
- Laboratory of Gene Therapy, Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
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14
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Kumar D, Das M, Sauceda C, Ellies LG, Kuo K, Parwal P, Kaur M, Jih L, Bandyopadhyay GK, Burton D, Loomba R, Osborn O, Webster NJ. Degradation of splicing factor SRSF3 contributes to progressive liver disease. J Clin Invest 2019; 129:4477-4491. [PMID: 31393851 DOI: 10.1172/jci127374] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Serine rich splicing factor 3 (SRSF3) plays a critical role in liver function and its loss promotes chronic liver damage and regeneration. As a consequence, genetic deletion of SRSF3 in hepatocytes caused progressive liver disease and ultimately led to hepatocellular carcinoma. Here we show that SRSF3 is decreased in human liver samples with non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), or cirrhosis that was associated with alterations in RNA splicing of known SRSF3 target genes. Hepatic SRSF3 expression was similarly decreased and RNA splicing dysregulated in mouse models of NAFLD and NASH. We showed that palmitic acid-induced oxidative stress caused conjugation of the ubiquitin like NEDD8 protein to SRSF3 and proteasome mediated degradation. SRSF3 was selectively neddylated at lysine11 and mutation of this residue (SRSF3-K11R) was sufficient to prevent both SRSF3 degradation and alterations in RNA splicing. Finally prevention of SRSF3 degradation in vivo partially protected mice from hepatic steatosis, fibrosis and inflammation. These results highlight a neddylation-dependent mechanism regulating gene expression in the liver that is disrupted in early metabolic liver disease and may contribute to the progression to NASH, cirrhosis and ultimately hepatocellular carcinoma.
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Affiliation(s)
- Deepak Kumar
- VA San Diego Healthcare System, San Diego, California, USA.,Department of Medicine
| | | | - Consuelo Sauceda
- VA San Diego Healthcare System, San Diego, California, USA.,Department of Medicine
| | - Lesley G Ellies
- Department of Pathology, and.,Moores Cancer Center, UCSD, La Jolla, California, USA
| | | | | | | | - Lily Jih
- VA San Diego Healthcare System, San Diego, California, USA
| | | | - Douglas Burton
- VA San Diego Healthcare System, San Diego, California, USA
| | - Rohit Loomba
- Department of Medicine.,Moores Cancer Center, UCSD, La Jolla, California, USA
| | | | - Nicholas Jg Webster
- VA San Diego Healthcare System, San Diego, California, USA.,Department of Medicine.,Moores Cancer Center, UCSD, La Jolla, California, USA
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15
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Hale MA, Richardson JI, Day RC, McConnell OL, Arboleda J, Wang ET, Berglund JA. An engineered RNA binding protein with improved splicing regulation. Nucleic Acids Res 2019; 46:3152-3168. [PMID: 29309648 PMCID: PMC5888374 DOI: 10.1093/nar/gkx1304] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 12/19/2017] [Indexed: 01/08/2023] Open
Abstract
The muscleblind-like (MBNL) family of proteins are key developmental regulators of alternative splicing. Sequestration of MBNL proteins by expanded CUG/CCUG repeat RNA transcripts is a major pathogenic mechanism in the neuromuscular disorder myotonic dystrophy (DM). MBNL1 contains four zinc finger (ZF) motifs that form two tandem RNA binding domains (ZF1-2 and ZF3-4) which each bind YGCY RNA motifs. In an effort to determine the differences in function between these domains, we designed and characterized synthetic MBNL proteins with duplicate ZF1-2 or ZF3-4 domains, referred to as MBNL-AA and MBNL-BB, respectively. Analysis of splicing regulation revealed that MBNL-AA had up to 5-fold increased splicing activity while MBNL-BB had 4-fold decreased activity compared to a MBNL protein with the canonical arrangement of zinc finger domains. RNA binding analysis revealed that the variations in splicing activity are due to differences in RNA binding specificities between the two ZF domains rather than binding affinity. Our findings indicate that ZF1-2 drives splicing regulation via recognition of YGCY RNA motifs while ZF3-4 acts as a general RNA binding domain. Our studies suggest that synthetic MBNL proteins with improved or altered splicing activity have the potential to be used as both tools for investigating splicing regulation and protein therapeutics for DM and other microsatellite diseases.
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Affiliation(s)
- Melissa A Hale
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA
| | - Jared I Richardson
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA
| | - Ryan C Day
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA
| | - Ona L McConnell
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA.,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Juan Arboleda
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA.,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - Eric T Wang
- Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA.,Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA
| | - J Andrew Berglund
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA.,Center for NeuroGenetics, University of Florida, Gainesville, FL 32610, USA
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16
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Hale MA, Johnson NE, Berglund JA. Repeat-associated RNA structure and aberrant splicing. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2019; 1862:194405. [PMID: 31323433 DOI: 10.1016/j.bbagrm.2019.07.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/11/2019] [Accepted: 07/12/2019] [Indexed: 12/13/2022]
Abstract
Over 30 hereditary disorders attributed to the expansion of microsatellite repeats have been identified. Despite variant nucleotide content, number of consecutive repeats, and different locations in the genome, many of these diseases have pathogenic RNA gain-of-function mechanisms. The repeat-containing RNAs can form structures in vitro predicted to contribute to the disease through assembly of intracellular RNA aggregates termed foci. The expanded repeat RNAs within these foci sequester RNA binding proteins (RBPs) with important roles in the regulation of RNA metabolism, most notably alternative splicing (AS). These deleterious interactions lead to downstream alterations in transcriptome-wide AS directly linked with disease symptoms. This review summarizes existing knowledge about the association between the repeat RNA structures and RBPs as well as the resulting aberrant AS patterns, specifically in the context of myotonic dystrophy. The connection between toxic, structured RNAs and dysregulation of AS in other repeat expansion diseases is also discussed. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.
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Affiliation(s)
- Melissa A Hale
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Nicholas E Johnson
- Department of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - J Andrew Berglund
- The RNA Institute, Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA.
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17
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Vella V, Milluzzo A, Scalisi NM, Vigneri P, Sciacca L. Insulin Receptor Isoforms in Cancer. Int J Mol Sci 2018; 19:ijms19113615. [PMID: 30453495 PMCID: PMC6274710 DOI: 10.3390/ijms19113615] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/05/2018] [Accepted: 11/13/2018] [Indexed: 12/17/2022] Open
Abstract
The insulin receptor (IR) mediates both metabolic and mitogenic effects especially when overexpressed or in clinical conditions with compensatory hyperinsulinemia, due to the metabolic pathway resistance, as obesity diabetes. In many cancers, IR is overexpressed preferentially as IR-A isoform, derived by alternative splicing of exon 11. The IR-A overexpression, and the increased IR-A:IR-B ratio, are mechanisms that promote the mitogenic response of cancer cells to insulin and IGF-2, which is produced locally by both epithelial and stromal cancer cells. In cancer IR-A, isoform predominance may occur for dysregulation at both mRNA transcription and post-transcription levels, including splicing factors, non-coding RNAs and protein degradation. The mechanisms that regulate IR isoform expression are complex and not fully understood. The IR isoform overexpression may play a role in cancer cell stemness, in tumor progression and in resistance to target therapies. From a clinical point of view, the IR-A overexpression in cancer may be a determinant factor for the resistance to IGF-1R target therapies for this issue. IR isoform expression in cancers may have the meaning of a predictive biomarker and co-targeting IGF-1R and IR-A may represent a new more efficacious treatment strategy.
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Affiliation(s)
- Veronica Vella
- Department of Clinical and Experimental Medicine, Endocrinology Section, University of Catania Medical School, Garibaldi-Nesima Hospital, via Palermo 636, 95122 Catania, Italy.
- School of Human and Social Science, University "Kore" of Enna, 94100 Enna, Italy.
| | - Agostino Milluzzo
- Department of Clinical and Experimental Medicine, Endocrinology Section, University of Catania Medical School, Garibaldi-Nesima Hospital, via Palermo 636, 95122 Catania, Italy.
| | - Nunzio Massimo Scalisi
- Department of Clinical and Experimental Medicine, Endocrinology Section, University of Catania Medical School, Garibaldi-Nesima Hospital, via Palermo 636, 95122 Catania, Italy.
| | - Paolo Vigneri
- Department of Clinical and Experimental Medicine, University of Catania Medical School, Center of Experimental Oncology and Hematology, A.O.U. Policlinico Vittorio Emanuele, via Santa Sofia, 78, 95123 Catania, Italy.
| | - Laura Sciacca
- Department of Clinical and Experimental Medicine, Endocrinology Section, University of Catania Medical School, Garibaldi-Nesima Hospital, via Palermo 636, 95122 Catania, Italy.
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18
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Cywoniuk P, Taylor K, Sznajder ŁJ, Sobczak K. Hybrid splicing minigene and antisense oligonucleotides as efficient tools to determine functional protein/RNA interactions. Sci Rep 2017; 7:17587. [PMID: 29242583 PMCID: PMC5730568 DOI: 10.1038/s41598-017-17816-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/01/2017] [Indexed: 12/16/2022] Open
Abstract
Alternative splicing is a complex process that provides a high diversity of proteins from a limited number of protein-coding genes. It is governed by multiple regulatory factors, including RNA-binding proteins (RBPs), that bind to specific RNA sequences embedded in a specific structure. The ability to predict RNA-binding regions recognized by RBPs using whole-transcriptome approaches can deliver a multitude of data, including false-positive hits. Therefore, validation of the global results is indispensable. Here, we report the development of an efficient and rapid approach based on a modular hybrid minigene combined with antisense oligonucleotides to enable verification of functional RBP-binding sites within intronic and exonic sequences of regulated pre-mRNA. This approach also provides valuable information regarding the regulatory properties of pre-mRNA, including the RNA secondary structure context. We also show that the developed approach can be used to effectively identify or better characterize the inhibitory properties of potential therapeutic agents for myotonic dystrophy, which is caused by sequestration of specific RBPs, known as muscleblind-like proteins, by mutated RNA with expanded CUG repeats.
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Affiliation(s)
- Piotr Cywoniuk
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614, Poznan, Poland
| | - Katarzyna Taylor
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614, Poznan, Poland
| | - Łukasz J Sznajder
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614, Poznan, Poland.,Center for NeuroGenetics and the Genetics Institute, Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida,, Gainesville, Florida, 32610-3610, USA
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614, Poznan, Poland.
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19
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Tsuji-Hosokawa A, Takasawa K, Nomura R, Miyakawa Y, Numakura C, Hijikata A, Shirai T, Ogawa Y, Kashimada K, Morio T. Molecular mechanisms of insulin resistance in 2 cases of primary insulin receptor defect-associated diseases. Pediatr Diabetes 2017; 18:917-924. [PMID: 28181734 DOI: 10.1111/pedi.12508] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Defects of the insulin receptor gene ( INSR ) cause wide spectra of congenital insulin resistance. Monoallelic defects result in milder insulin-resistant diabetes mellitus with acanthosis nigricans (IRAN, type A). Whereas, leprechaunism (Donahue syndrome), the most severe condition with lethality during the infantile period is caused by biallelic defects of INSR . MATERIALS AND METHODS We detected 2 missense mutations in 2 cases of leprechaunism and IRAN, type A, and reduced mRNA expression in the leprechaunism case. We performed an in vitro analysis to confirm that the 2 missense mutations are causative. RESULTS The heterozygote mutations c.3436G>A (p.Gly1146Arg) and c.294C>A (p.Ser98Arg) were identified in a male patient with IRAN, type A and a female patient with leprechaunism, respectively. Gly1146Arg was previously reported in a diabetic case without precise functional analyses, and Ser98Arg is a novel mutation. Gly1146 and Ser98 are located on the tyrosine kinase domain and ligand-binding domain of INSR, respectively, and in vitro analyses (assay for insulin binding and phosphorylation) revealed that each mutation disrupted protein functions and properties. In the leprechaunism case, mutations in INSR other than Ser98Arg were not identified, and qRT-PCR analysis revealed that mRNA expression of INSR in lymphocytes was reduced in the leprechaunism case. CONCLUSION Our study indicates that the 2 missense mutations of INSR , Gly1146Arg, and Ser98Arg, are responsible for insulin resistance, and, suggests that mutations not contained within INSR , but leading to decreased INSR expression should be considered for the patients who show insulin resistance without any mutations in the coding sequence of INSR.
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Affiliation(s)
- Atsumi Tsuji-Hosokawa
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kei Takasawa
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Risa Nomura
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yuichi Miyakawa
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Chikahiko Numakura
- Department of Pediatrics, Yamagata University School of Medicine, Yamagata, Japan
| | - Atsushi Hijikata
- Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Tsuyoshi Shirai
- Faculty of Bioscience, Nagahama Institute of Bio-Science and Technology, Nagahama, Japan
| | - Yoshihiro Ogawa
- Department of Molecular Endocrinology and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kenichi Kashimada
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tomohiro Morio
- Department of Pediatrics and Developmental Biology, Tokyo Medical and Dental University, Tokyo, Japan
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20
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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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21
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IGF1 and IGF2 specificities to the two insulin receptor isoforms are determined by insulin receptor amino acid 718. PLoS One 2017; 12:e0178885. [PMID: 28570711 PMCID: PMC5453582 DOI: 10.1371/journal.pone.0178885] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/19/2017] [Indexed: 12/18/2022] Open
Abstract
Methods Alanine scan of insulin receptor (IR)-B exon 11 and site-directed mutagenesis of amino acid 718 in human IR-A and IR-B were performed. Ligand affinities to wild type and mutated receptors were studied by displacement of radioactive insulin in binding assay on secreted soluble midi receptors or solubilized semi-purified full length receptors stably expressed in Baby Hamster Kidney cells. Phosphorylation of IR in response to insulin, IGF1 and IGF2 was measured using ELISA. Results Insulin, insulin detemir and insulin glargine maximally showed two fold differences in affinity for human IR-A and IR-B, but IGF1 and IGF2 had up to 10 fold preference for IR-A. Alanine scan of exon 11 revealed that position 718 is important for low IGF1 affinity to IR-B. Mutational analysis of amino acid residue 718 in IR-A and IR-B demonstrated that charge is important for IGF1 and IGF2 affinity but not important for insulin affinity. The affinity of IGF1 and IGF2 for the mutant IR-A P718K was comparable to the wild type IR-B whereas the affinity of IGF1 and IGF2 for the mutant IR-B K718P was comparable to the wild type IR-A. Changes in affinity were also reflected in the IR activation pattern. Conclusion Mutating position 718 in human IR-B to the proline found at position 718 in human IR-A increased IGF1 and IGF2 affinity to a level comparable to IR-A and mutating position 718 in IR-A to the lysine found at position 718 in IR-B decreased IGF1 and IGF2 affinity to a level comparable to IR-B, whereas a negatively charged glutamate did not. These changes in the affinities were also reflected in the IR phosphorylation pattern, meaning that position 718 is important for both affinity and activation of the receptor. It should be emphasized that none of the mutations affected insulin affinity, indicating that the mutations did not alter the overall receptor structure and that the effect is ligand specific.
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22
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Sznajder ŁJ, Michalak M, Taylor K, Cywoniuk P, Kabza M, Wojtkowiak-Szlachcic A, Matłoka M, Konieczny P, Sobczak K. Mechanistic determinants of MBNL activity. Nucleic Acids Res 2016; 44:10326-10342. [PMID: 27733504 PMCID: PMC5137450 DOI: 10.1093/nar/gkw915] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 10/05/2016] [Indexed: 11/13/2022] Open
Abstract
Muscleblind-like (MBNL) proteins are critical RNA processing factors in development. MBNL activity is disrupted in the neuromuscular disease myotonic dystrophy type 1 (DM1), due to the instability of a non-coding microsatellite in the DMPK gene and the expression of CUG expansion (CUGexp) RNAs. Pathogenic interactions between MBNL and CUGexp RNA lead to the formation of nuclear complexes termed foci and prevent MBNL function in pre-mRNA processing. The existence of multiple MBNL genes, as well as multiple protein isoforms, raises the question of whether different MBNL proteins possess unique or redundant functions. To address this question, we coexpressed three MBNL paralogs in cells at equivalent levels and characterized both specific and redundant roles of these proteins in alternative splicing and RNA foci dynamics. When coexpressed in the same cells, MBNL1, MBNL2 and MBNL3 bind the same RNA motifs with different affinities. While MBNL1 demonstrated the highest splicing activity, MBNL3 showed the lowest. When forming RNA foci, MBNL1 is the most mobile paralog, while MBNL3 is rather static and the most densely packed on CUGexp RNA. Therefore, our results demonstrate that MBNL paralogs and gene-specific isoforms possess inherent functional differences, an outcome that could be enlisted to improve therapeutic strategies for DM1.
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Affiliation(s)
- Łukasz J Sznajder
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Michał Michalak
- Department of Molecular and Cellular Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Katarzyna Taylor
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Piotr Cywoniuk
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Michał Kabza
- Department of Bioinformatics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Agnieszka Wojtkowiak-Szlachcic
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Magdalena Matłoka
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Patryk Konieczny
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznań, Poland
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23
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Dose-Dependent Regulation of Alternative Splicing by MBNL Proteins Reveals Biomarkers for Myotonic Dystrophy. PLoS Genet 2016; 12:e1006316. [PMID: 27681373 PMCID: PMC5082313 DOI: 10.1371/journal.pgen.1006316] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 08/23/2016] [Indexed: 01/23/2023] Open
Abstract
Alternative splicing is a regulated process that results in expression of
specific mRNA and protein isoforms. Alternative splicing factors determine the
relative abundance of each isoform. Here we focus on MBNL1, a splicing factor
misregulated in the disease myotonic dystrophy. By altering the concentration of
MBNL1 in cells across a broad dynamic range, we show that different splicing
events require different amounts of MBNL1 for half-maximal response, and respond
more or less steeply to MBNL1. Motifs around MBNL1 exon 5 were studied to assess
how cis-elements mediate the MBNL1 dose-dependent splicing
response. A framework was developed to estimate MBNL concentration using
splicing responses alone, validated in the cell-based model, and applied to
myotonic dystrophy patient muscle. Using this framework, we evaluated the
ability of individual and combinations of splicing events to predict functional
MBNL concentration in human biopsies, as well as their performance as biomarkers
to assay mild, moderate, and severe cases of DM. Our studies provide insight into the mechanisms of myotonic dystrophy, the most
common adult form of muscular dystrophy. In this disease, a family of RNA
binding proteins is sequestered by toxic RNA, which leads to mis-regulation and
disease symptoms. We have created a cellular model with one of these family
members to study how these RNA binding proteins function in the absence of the
toxic RNA. In parallel, we analyzed transcriptomic data from over 50 individuals
(44 affected by myotonic dystrophy) with a range of disease severity. The
results from the transcriptomic data provide a rational approach to select
biomarkers for clinical research and therapeutic trials.
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Oddo JC, Saxena T, McConnell OL, Berglund JA, Wang ET. Conservation of context-dependent splicing activity in distant Muscleblind homologs. Nucleic Acids Res 2016; 44:8352-62. [PMID: 27557707 PMCID: PMC5041496 DOI: 10.1093/nar/gkw735] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/11/2016] [Indexed: 12/15/2022] Open
Abstract
The Muscleblind (MBL) protein family is a deeply conserved family of RNA binding proteins that regulate alternative splicing, alternative polyadenylation, RNA stability and RNA localization. Their inactivation due to sequestration by expanded CUG repeats causes symptoms in the neuromuscular disease myotonic dystrophy. MBL zinc fingers are the most highly conserved portion of these proteins, and directly interact with RNA. We identified putative MBL homologs in Ciona intestinalis and Trichoplax adhaerens, and investigated their ability, as well as that of MBL homologs from human/mouse, fly and worm, to regulate alternative splicing. We found that all homologs can regulate alternative splicing in mouse cells, with some regulating over 100 events. The cis-elements through which each homolog exerts its splicing activities are likely to be highly similar to mammalian Muscleblind-like proteins (MBNLs), as suggested by motif analyses and the ability of expanded CUG repeats to inactivate homolog-mediated splicing. While regulation of specific target exons by MBL/MBNL has not been broadly conserved across these species, genes enriched for MBL/MBNL binding sites in their introns may play roles in cell adhesion, ion transport and axon guidance, among other biological pathways, suggesting a specific, conserved role for these proteins across a broad range of metazoan species.
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Affiliation(s)
- Julia C Oddo
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Tanvi Saxena
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - Ona L McConnell
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
| | - J Andrew Berglund
- Center for Neurogenetics, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA Department of Chemistry and Biochemistry and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Eric T Wang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32610, USA Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA
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25
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Insulin receptor alternative splicing is regulated by insulin signaling and modulates beta cell survival. Sci Rep 2016; 6:31222. [PMID: 27526875 PMCID: PMC4985653 DOI: 10.1038/srep31222] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 07/14/2016] [Indexed: 12/03/2022] Open
Abstract
Type 2 Diabetes (T2DM) affects more than 300 million people worldwide. One of the hallmarks of T2DM is peripheral insulin resistance, in part due to unproductive insulin signaling through the insulin receptor. The insulin receptor (INSR) exists as two isoforms, INSR-A and INSR-B, which results from skipping or inclusion of exon 11 respectively. What determines the relative abundance of the different insulin receptor splice variants is unknown. Moreover, it is not yet clear what the physiological roles of each of the isoforms are in normal and diseased beta cells. In this study, we show that insulin induces INSR exon 11 inclusion in pancreatic beta cells in both human and mouse. This occurs through activation of the Ras-MAPK/ERK signaling pathway and up-regulation of the splicing factor SRSF1. Induction of exon 11 skipping by a splice-site competitive antisense oligonucleotide inhibited the MAPK-ERK signaling pathway downstream of the insulin receptor, sensitizing the pancreatic β-cell line MIN6 to stress-induced apoptosis and lipotoxicity. These results assign to insulin a regulatory role in INSR alternative splicing through the Ras-MAPK/ERK signaling pathway. We suggest that in beta cells, INSR-B has a protective role, while INSR-A expression sensitizes beta cells to programmed cell death.
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Tomioka M, Naito Y, Kuroyanagi H, Iino Y. Splicing factors control C. elegans behavioural learning in a single neuron by producing DAF-2c receptor. Nat Commun 2016; 7:11645. [PMID: 27198602 PMCID: PMC4876481 DOI: 10.1038/ncomms11645] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/17/2016] [Indexed: 01/18/2023] Open
Abstract
Alternative splicing generates protein diversity essential for neuronal properties. However, the precise mechanisms underlying this process and its relevance to physiological and behavioural functions are poorly understood. To address these issues, we focused on a cassette exon of the Caenorhabditis elegans insulin receptor gene daf-2, whose proper variant expression in the taste receptor neuron ASER is critical for taste-avoidance learning. We show that inclusion of daf-2 exon 11.5 is restricted to specific neuron types, including ASER, and is controlled by a combinatorial action of evolutionarily conserved alternative splicing factors, RBFOX, CELF and PTB families of proteins. Mutations of these factors cause a learning defect, and this defect is relieved by DAF-2c (exon 11.5+) isoform expression only in a single neuron ASER. Our results provide evidence that alternative splicing regulation of a single critical gene in a single critical neuron is essential for learning ability in an organism. Little is known about the molecular mechanisms regulating neuron-specific alternative splicing. Here, the authors identify a combination of RNA-binding proteins regulating neuron-specific expression of the C. elegans insulin receptor isoform DAF-2c and find disrupting these factors leads to learning deficits.
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Affiliation(s)
- Masahiro Tomioka
- Molecular Genetics Research Laboratory, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Yasuki Naito
- Molecular Genetics Research Laboratory, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo 113-8510, Japan
| | - Yuichi Iino
- Molecular Genetics Research Laboratory, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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27
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Westermeier F, Sáez T, Arroyo P, Toledo F, Gutiérrez J, Sanhueza C, Pardo F, Leiva A, Sobrevia L. Insulin receptor isoforms: an integrated view focused on gestational diabetes mellitus. Diabetes Metab Res Rev 2016; 32:350-65. [PMID: 26431063 DOI: 10.1002/dmrr.2729] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 09/14/2015] [Accepted: 09/27/2015] [Indexed: 12/17/2022]
Abstract
The human insulin receptor (IR) exists in two isoforms that differ by the absence (IR-A) or the presence (IR-B) of a 12-amino acid segment encoded by exon 11. Both isoforms are functionally distinct regarding their binding affinities and intracellular signalling. However, the underlying mechanisms related to their cellular functions in several tissues are only partially understood. In this review, we summarize the current knowledge in this field regarding the alternative splicing of IR isoform, tissue-specific distribution and signalling both in physiology and disease, with an emphasis on the human placenta in gestational diabetes mellitus (GDM). Furthermore, we discuss the clinical relevance of IR isoforms highlighted by findings that show altered insulin signalling due to differential IR-A and IR-B expression in human placental endothelium in GDM pregnancies. Future research and clinical studies focused on the role of IR isoform signalling might provide novel therapeutic targets for treating GDM to improve the adverse maternal and neonatal outcomes.
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Affiliation(s)
- F Westermeier
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
- Advanced Centre for Chronic Diseases (ACCDiS), Faculty of Chemical & Pharmaceutical Sciences and Faculty of Medicine, Universidad de Chile, Santiago, Chile
- Faculty of Science, Universidad San Sebastián, Santiago, Chile
| | - T Sáez
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
- University Medical Centre Groningen (UMCG), Faculty of Medicine, University of Groningen, Groningen, The Netherlands
| | - P Arroyo
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - F Toledo
- Department of Basic Sciences, Faculty of Sciences, Universidad del Bío-Bío, Chillán, Chile
| | - J Gutiérrez
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
- Cellular Signalling and Differentiation Laboratory (CSDL), School of Medical Technology, Health Sciences Faculty, Universidad San Sebastian, Santiago, Chile
| | - C Sanhueza
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - F Pardo
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - A Leiva
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - L Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
- Department of Physiology, Faculty of Pharmacy, Universidad de Sevilla, Seville, Spain
- University of Queensland Centre for Clinical Research (UQCCR), Faculty of Medicine and Biomedical Sciences, University of Queensland, Queensland, Australia
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28
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Roles for RNA-binding proteins in development and disease. Brain Res 2016; 1647:1-8. [PMID: 26972534 DOI: 10.1016/j.brainres.2016.02.050] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 02/24/2016] [Accepted: 02/25/2016] [Indexed: 12/13/2022]
Abstract
RNA-binding protein activities are highly regulated through protein levels, intracellular localization, and post-translation modifications. During development, mRNA processing of specific gene sets is regulated through manipulation of functional RNA-binding protein activities. The impact of altered RNA-binding protein activities also affects human diseases in which there are either a gain-of-function or loss-of-function causes pathogenesis. We will discuss RNA-binding proteins and their normal developmental RNA metabolism and contrast how their function is disrupted in disease. This article is part of a Special Issue entitled SI:RNA Metabolism in Disease.
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Zhang BW, Cai HF, Wei XF, Sun JJ, Lan XY, Lei CZ, Lin FP, Qi XL, Plath M, Chen H. miR-30-5p Regulates Muscle Differentiation and Alternative Splicing of Muscle-Related Genes by Targeting MBNL. Int J Mol Sci 2016; 17:ijms17020182. [PMID: 26840300 PMCID: PMC4783916 DOI: 10.3390/ijms17020182] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 12/26/2015] [Accepted: 01/22/2016] [Indexed: 02/07/2023] Open
Abstract
MicroRNAs (miRNAs), a class of single stranded, small (~22 nucleotides), non-coding RNAs, play an important role in muscle development. We focused on the role of the miR-30-5p family during bovine muscle development from previous high-throughput sequencing results and analyzed their expression profiles. MHC and MyoG mRNAs expression as well as their proteins were suppressed in differentiated C2C12 cells, suggesting the importance of miR-30-5p in muscle development. MBNL, the candidate target of miR-30-5p, is an alternative splicing regulation factor. MBNL1 and MBNL3 have opposite effects on muscle differentiation. Our results confirmed that miR-30a-5p and miR-30e-5p repress the expression of MBNL1, MBNL2 and MBNL3, whereas miR-30b-5p inhibits MBNL1 and MBNL2 expression. This provides direct evidence that MBNL expression can be flexibly regulated by miR-30-5p. Previous studies showed that MBNL1 promotes exon inclusion of two muscle-related genes (Trim55 and INSR). Through RNA splicing studies, we found that miR-30-5p had an effect on their alternative splicing, which means miR-30-5p via MBNL1 could be integrated into muscle signaling pathways in which INSR or Trim55 are located. In conclusion, miR-30-5p could inhibit muscle cell differentiation and regulate the alternative splicing of Trim55 and INSR by targeting MBNL. These results promote the understanding of the function of miRNAs in muscle development.
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Affiliation(s)
- Bo-Wen Zhang
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Han-Fang Cai
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Xue-Feng Wei
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Jia-Jie Sun
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Xian-Yong Lan
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Chu-Zhao Lei
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Feng-Peng Lin
- Department of Animal Husbandry, Bureau of Biyang County of Henan province, Biyang 463700, Henan, China.
| | - Xing-Lei Qi
- Department of Animal Husbandry, Bureau of Biyang County of Henan province, Biyang 463700, Henan, China.
| | - Martin Plath
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
| | - Hong Chen
- Shaanxi Key Laboratory of Agricultural Molecular Biology, College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, China.
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Bondy-Chorney E, Crawford Parks TE, Ravel-Chapuis A, Klinck R, Rocheleau L, Pelchat M, Chabot B, Jasmin BJ, Côté J. Staufen1 Regulates Multiple Alternative Splicing Events either Positively or Negatively in DM1 Indicating Its Role as a Disease Modifier. PLoS Genet 2016; 12:e1005827. [PMID: 26824521 PMCID: PMC4733145 DOI: 10.1371/journal.pgen.1005827] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 01/05/2016] [Indexed: 01/10/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a neuromuscular disorder caused by an expansion of CUG repeats in the 3' UTR of the DMPK gene. The CUG repeats form aggregates of mutant mRNA, which cause misregulation and/or sequestration of RNA-binding proteins, causing aberrant alternative splicing in cells. Previously, we showed that the multi-functional RNA-binding protein Staufen1 (Stau1) was increased in skeletal muscle of DM1 mouse models and patients. We also showed that Stau1 rescues the alternative splicing profile of pre-mRNAs, e.g. the INSR and CLC1, known to be aberrantly spliced in DM1. In order to explore further the potential of Stau1 as a therapeutic target for DM1, we first investigated the mechanism by which Stau1 regulates pre-mRNA alternative splicing. We report here that Stau1 regulates the alternative splicing of exon 11 of the human INSR via binding to Alu elements located in intron 10. Additionally, using a high-throughput RT-PCR screen, we have identified numerous Stau1-regulated alternative splicing events in both WT and DM1 myoblasts. A number of these aberrant ASEs in DM1, including INSR exon 11, are rescued by overexpression of Stau1. However, we find other ASEs in DM1 cells, where overexpression of Stau1 shifts the splicing patterns away from WT conditions. Moreover, we uncovered that Stau1-regulated ASEs harbour Alu elements in intronic regions flanking the alternative exon more than non-Stau1 targets. Taken together, these data highlight the broad impact of Stau1 as a splicing regulator and suggest that Stau1 may act as a disease modifier in DM1.
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Affiliation(s)
- Emma Bondy-Chorney
- Department of Cellular and Molecular Medicine, University of Ottawa; Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Tara E. Crawford Parks
- Department of Cellular and Molecular Medicine, University of Ottawa; Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Aymeric Ravel-Chapuis
- Department of Cellular and Molecular Medicine, University of Ottawa; Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Roscoe Klinck
- Département de microbiologie et d'infectiologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Lynda Rocheleau
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Martin Pelchat
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Benoit Chabot
- Département de microbiologie et d'infectiologie, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Bernard J. Jasmin
- Department of Cellular and Molecular Medicine, University of Ottawa; Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
| | - Jocelyn Côté
- Department of Cellular and Molecular Medicine, University of Ottawa; Centre for Neuromuscular Disease, Ottawa, Ontario, Canada
- * E-mail:
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31
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Takarada T, Nishida A, Takeuchi A, Lee T, Takeshima Y, Matsuo M. Resveratrol enhances splicing of insulin receptor exon 11 in myotonic dystrophy type 1 fibroblasts. Brain Dev 2015; 37:661-8. [PMID: 25476247 DOI: 10.1016/j.braindev.2014.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 11/07/2014] [Accepted: 11/07/2014] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Myotonic dystrophy type 1 (DM1) is characterized by splicing abnormalities caused by CUG expansion of the DMPK gene transcript. Splicing of exon 11 of the insulin receptor (IR) gene is deregulated to suppress exon 11 inclusion into mRNA in DM1. Consequently, the exon 11-deleted IR isoform that is less sensitive to insulin is predominantly produced, leading to glucose intolerance in DM1. Upregulation of exon 11 retaining full-length IR mRNA is a potential way to recover insulin sensitivity in DM1. METHODS We examined candidate chemicals for their ability to enhance inclusion of exon 11 of the IR gene in cultured cells by reverse transcription-PCR amplification of a fragment extending from exons 10 to 12 of IR mRNA. RESULTS We revealed that resveratrol (RES) enhanced the percentage of exon 11-containing IR mRNA among the total IR mRNA in HeLa cells. The RES-mediated enhancement of exon 11 inclusion was cell-specific and highest in fibroblasts. We tested RES on four fibroblast samples from three generations of one DM1 family. In each sample, RES treatment significantly upregulated the percentage of exon 11-containing IR mRNA to levels higher than that of the control, irrespective of the length of the sample's CTG repeat expansion. DISCUSSION A natural compound, RES, was shown for the first time to upregulate the full-length IR mRNA in fibroblasts from DM1 cases. Our results provide the justification of RES as a leading compound to improve glucose tolerance in DM1.
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Affiliation(s)
- Toru Takarada
- Department of Medical Rehabilitation, Faculty of Rehabilitation, Kobegakuin University, Nishi, Kobe 6512180, Japan; Kobe Pharmaceutical University, Higashinada, Kobe 6588558, Japan
| | - Atsushi Nishida
- Department of Medical Rehabilitation, Faculty of Rehabilitation, Kobegakuin University, Nishi, Kobe 6512180, Japan
| | - Atsuko Takeuchi
- Kobe Pharmaceutical University, Higashinada, Kobe 6588558, Japan
| | - Tomoko Lee
- Department of Pediatrics, Hyogo College of Medicine, Nishinomiya 6638131, Japan
| | - Yasuhiro Takeshima
- Department of Pediatrics, Hyogo College of Medicine, Nishinomiya 6638131, Japan
| | - Masafumi Matsuo
- Department of Medical Rehabilitation, Faculty of Rehabilitation, Kobegakuin University, Nishi, Kobe 6512180, Japan.
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Chau A, Kalsotra A. Developmental insights into the pathology of and therapeutic strategies for DM1: Back to the basics. Dev Dyn 2015; 244:377-90. [PMID: 25504326 DOI: 10.1002/dvdy.24240] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 11/25/2014] [Accepted: 11/27/2014] [Indexed: 12/25/2022] Open
Abstract
Myotonic Dystrophy type 1 (DM1), the most prevalent adult onset muscular dystrophy, is a trinucleotide repeat expansion disease caused by CTG expansion in the 3'-UTR of DMPK gene. This expansion results in the expression of toxic gain-of-function RNA that forms ribonuclear foci and disrupts normal activities of RNA-binding proteins belonging to the MBNL and CELF families. Changes in alternative splicing, translation, localization, and mRNA stability due to sequestration of MBNL proteins and up-regulation of CELF1 are key to DM1 pathology. However, recent discoveries indicate that pathogenic mechanisms of DM1 involves many other factors as well, including repeat associated translation, activation of PKC-dependent signaling pathway, aberrant polyadenylation, and microRNA deregulation. Expression of the toxic repeat RNA culminates in the developmental remodeling of the transcriptome, which produces fetal isoforms of proteins that are unable to fulfill the physiological requirements of adult tissues. This review will describe advances in the understanding of DM1 pathogenesis as well as current therapeutic developments for DM1.
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Affiliation(s)
- Anthony Chau
- Department of Biochemistry, University of Illinois, Urbana-Champaign, Illinois; Department of Medical Biochemistry, University of Illinois, Urbana-Champaign, Illinois; Institute of Genomic Biology, University of Illinois, Urbana-Champaign, Illinois
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33
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Villate O, Turatsinze JV, Mascali LG, Grieco FA, Nogueira TC, Cunha DA, Nardelli TR, Sammeth M, Salunkhe VA, Esguerra JLS, Eliasson L, Marselli L, Marchetti P, Eizirik DL. Nova1 is a master regulator of alternative splicing in pancreatic beta cells. Nucleic Acids Res 2014; 42:11818-30. [PMID: 25249621 PMCID: PMC4191425 DOI: 10.1093/nar/gku861] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Alternative splicing (AS) is a fundamental mechanism for the regulation of gene expression. It affects more than 90% of human genes but its role in the regulation of pancreatic beta cells, the producers of insulin, remains unknown. Our recently published data indicated that the ‘neuron-specific’ Nova1 splicing factor is expressed in pancreatic beta cells. We have presently coupled specific knockdown (KD) of Nova1 with RNA-sequencing to determine all splice variants and downstream pathways regulated by this protein in beta cells. Nova1 KD altered the splicing of nearly 5000 transcripts. Pathway analysis indicated that these genes are involved in exocytosis, apoptosis, insulin receptor signaling, splicing and transcription. In line with these findings, Nova1 silencing inhibited insulin secretion and induced apoptosis basally and after cytokine treatment in rodent and human beta cells. These observations identify a novel layer of regulation of beta cell function, namely AS controlled by key splicing regulators such as Nova1.
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Affiliation(s)
- Olatz Villate
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Jean-Valery Turatsinze
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Loriana G Mascali
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Fabio A Grieco
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Tatiane C Nogueira
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Daniel A Cunha
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Tarlliza R Nardelli
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
| | - Michael Sammeth
- Laboratório Nacional de Computação Científica (LNCC), Petrópolis Rio de Janeiro, 25651-076, Brazil
| | - Vishal A Salunkhe
- Lund University Diabetes Centre, Unit of Islet cell Exocytosis, Department of Clinical Sciences Malmö, Lund University, CRC 91-11, Jan Waldenströms gata 35, 205 02 Malmö, Sweden
| | - Jonathan L S Esguerra
- Lund University Diabetes Centre, Unit of Islet cell Exocytosis, Department of Clinical Sciences Malmö, Lund University, CRC 91-11, Jan Waldenströms gata 35, 205 02 Malmö, Sweden
| | - Lena Eliasson
- Lund University Diabetes Centre, Unit of Islet cell Exocytosis, Department of Clinical Sciences Malmö, Lund University, CRC 91-11, Jan Waldenströms gata 35, 205 02 Malmö, Sweden
| | - Lorella Marselli
- Department of Clinical and Experimental Medicine, Pancreatic Islet Cell Laboratory, University of Pisa, Pisa, 56126, Italy
| | - Piero Marchetti
- Department of Clinical and Experimental Medicine, Pancreatic Islet Cell Laboratory, University of Pisa, Pisa, 56126, Italy
| | - Decio L Eizirik
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels (ULB) B-1070, Belgium
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Konieczny P, Stepniak-Konieczna E, Sobczak K. MBNL proteins and their target RNAs, interaction and splicing regulation. Nucleic Acids Res 2014; 42:10873-87. [PMID: 25183524 PMCID: PMC4176163 DOI: 10.1093/nar/gku767] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Muscleblind-like (MBNL) proteins are key regulators of precursor and mature mRNA metabolism in mammals. Based on published and novel data, we explore models of tissue-specific MBNL interaction with RNA. We portray MBNL domains critical for RNA binding and splicing regulation, and the structure of MBNL's normal and pathogenic RNA targets, particularly in the context of myotonic dystrophy (DM), in which expanded CUG or CCUG repeat transcripts sequester several nuclear proteins including MBNLs. We also review the properties of MBNL/RNA complex, including recent data obtained from UV cross-linking and immunoprecipitation (CLIP-Seq), and discuss how this interaction shapes normal MBNL-dependent alternative splicing regulation. Finally, we review how this acquired knowledge about the pathogenic RNA structure and nature of MBNL sequestration can be translated into the design of therapeutic strategies against DM.
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Affiliation(s)
- Patryk Konieczny
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Ewa Stepniak-Konieczna
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
| | - Krzysztof Sobczak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Umultowska 89, 61-614 Poznan, Poland
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35
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Duan R, Sharma S, Xia Q, Garber K, Jin P. Towards Understanding RNA-Mediated Neurological Disorders. J Genet Genomics 2014; 41:473-84. [DOI: 10.1016/j.jgg.2014.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Revised: 08/10/2014] [Accepted: 08/12/2014] [Indexed: 12/14/2022]
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36
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Transcriptionally correlated subcellular dynamics of MBNL1 during lens development and their implication for the molecular pathology of myotonic dystrophy type 1. Biochem J 2014; 458:267-80. [PMID: 24354850 DOI: 10.1042/bj20130870] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
DM1 (myotonic dystrophy type 1) is caused by elongation of a CTG repeat in the DMPK (dystrophia myotonica-protein kinase) gene. mRNA transcripts containing these CUGexp (CUG expansion) repeats form accumulations, or foci, in the nucleus of the cell. The pathogenesis of DM1 is proposed to result from inappropriate patterns of alternative splicing caused by sequestration of the developmentally regulated alternative splicing factor MBNL1 (muscleblind-like 1) by these foci. Since eye lens cataract is a common feature of DM1 we have examined the distribution and dynamics of MBNL1 in lens epithelial cell lines derived from patients with DM1. The results of the present study demonstrate that only a small proportion of nuclear MBNL1 accumulates in CUGexp pre-mRNA foci. MBNL1 is, however, highly mobile and changes localization in response to altered transcription and splicing activity. Moreover, immunolocalization studies in lens sections suggest that a change in MBNL1 distribution is important during lens growth and differentiation. Although these data suggest that the loss of MBNL1 function due to accumulation in foci is an unlikely explanation for DM1 symptoms in the lens, they do demonstrate a strong relationship between the subcellular MBNL1 localization and pathways of cellular differentiation, providing an insight into the sensitivity of the lens to changes in MBNL1 distribution.
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37
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Guzmán-Gutiérrez E, Arroyo P, Salsoso R, Fuenzalida B, Sáez T, Leiva A, Pardo F, Sobrevia L. Role of Insulin and Adenosine in the Human Placenta Microvascular and Macrovascular Endothelial Cell Dysfunction in Gestational Diabetes Mellitus. Microcirculation 2014; 21:26-37. [DOI: 10.1111/micc.12077] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 07/18/2013] [Indexed: 12/19/2022]
Affiliation(s)
- Enrique Guzmán-Gutiérrez
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Pablo Arroyo
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Rocío Salsoso
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Bárbara Fuenzalida
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
- Biomedical Department; Faculty of Health Sciences; Universidad de Antofagasta; Antofagasta Chile
| | - Tamara Sáez
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Andrea Leiva
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Fabián Pardo
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL); Division of Obstetrics and Gynaecology; Medical Research Centre (CIM); School of Medicine; Faculty of Medicine; Pontificia Universidad Católica de Chile; Santiago Chile
- University of Queensland Centre for Clinical Research; Herston Queensland Australia
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38
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Cardani R, Bugiardini E, Renna LV, Rossi G, Colombo G, Valaperta R, Novelli G, Botta A, Meola G. Overexpression of CUGBP1 in skeletal muscle from adult classic myotonic dystrophy type 1 but not from myotonic dystrophy type 2. PLoS One 2013; 8:e83777. [PMID: 24376746 PMCID: PMC3869793 DOI: 10.1371/journal.pone.0083777] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 11/11/2013] [Indexed: 12/22/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are progressive multisystemic disorders caused by similar mutations at two different genetic loci. The common key feature of DM pathogenesis is nuclear accumulation of mutant RNA which causes aberrant alternative splicing of specific pre-mRNAs by altering the functions of two RNA binding proteins, MBNL1 and CUGBP1. However, DM1 and DM2 show disease-specific features that make them clearly separate diseases suggesting that other cellular and molecular pathways may be involved. In this study we have analysed the histopathological, and biomolecular features of skeletal muscle biopsies from DM1 and DM2 patients in relation to presenting phenotypes to better define the molecular pathogenesis. Particularly, the expression of CUGBP1 protein has been examined to clarify if this factor may act as modifier of disease-specific manifestations in DM. The results indicate that the splicing and muscle pathological alterations observed are related to the clinical phenotype both in DM1 and in DM2 and that CUGBP1 seems to play a role in classic DM1 but not in DM2. In conclusion, our results indicate that multisystemic disease spectrum of DM pathologies may not be explained only by spliceopathy thus confirming that the molecular pathomechanism of DM is more complex than that actually suggested.
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Affiliation(s)
- Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato, Milan, Italy
| | - Enrico Bugiardini
- Department of Neurology, University of Milan, IRCCS-Policlinico San Donato, Milan, Italy
| | - Laura V. Renna
- Department of Biosciences, University of Milan, Milan, Italy
| | - Giulia Rossi
- Department of Biomedicine and Prevention, Tor Vergata University of Rome, Rome, Italy
| | | | - Rea Valaperta
- Research Laboratories - Molecular Biology, IRCCS-Policlinico San Donato, Milan, Italy
| | | | - Annalisa Botta
- Department of Biomedicine and Prevention, Tor Vergata University of Rome, Rome, Italy
| | - Giovanni Meola
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS-Policlinico San Donato, Milan, Italy
- Department of Neurology, University of Milan, IRCCS-Policlinico San Donato, Milan, Italy
- * E-mail:
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39
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Coonrod LA, Nakamori M, Wang W, Carrell S, Hilton CL, Bodner MJ, Siboni RB, Docter AG, Haley MM, Thornton CA, Berglund JA. Reducing levels of toxic RNA with small molecules. ACS Chem Biol 2013; 8:2528-37. [PMID: 24028068 DOI: 10.1021/cb400431f] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Myotonic dystrophy (DM) is one of the most common forms of muscular dystrophy. DM is an autosomal dominant disease caused by a toxic gain of function RNA. The toxic RNA is produced from expanded noncoding CTG/CCTG repeats, and these CUG/CCUG repeats sequester the Muscleblind-like (MBNL) family of RNA binding proteins. The MBNL proteins are regulators of alternative splicing, and their sequestration has been linked with mis-splicing events in DM. A previously reported screen for small molecules found that pentamidine was able to improve splicing defects associated with DM. Biochemical experiments and cell and mouse model studies of the disease indicate that pentamidine and related compounds may work through binding the CTG*CAG repeat DNA to inhibit transcription. Analysis of a series of methylene linker analogues of pentamidine revealed that heptamidine reverses splicing defects and rescues myotonia in a DM1 mouse model.
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Affiliation(s)
| | - Masayuki Nakamori
- Department
of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, United States
| | - Wenli Wang
- Department
of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, United States
| | - Samuel Carrell
- Department
of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, United States
| | | | | | | | | | | | - Charles A. Thornton
- Department
of Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, United States
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40
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Echeverria GV, Cooper TA. Muscleblind-like 1 activates insulin receptor exon 11 inclusion by enhancing U2AF65 binding and splicing of the upstream intron. Nucleic Acids Res 2013; 42:1893-903. [PMID: 24185704 PMCID: PMC3919616 DOI: 10.1093/nar/gkt1020] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Alternative splicing regulates developmentally and tissue-specific gene expression programs, disruption of which have been implicated in numerous diseases. Muscleblind-like 1 (MBNL1) regulates splicing transitions, which are disrupted on loss of MBNL1 function in myotonic dystrophy type 1 (DM1). One such event is MBNL1-mediated activation of insulin receptor exon 11 inclusion, which requires an intronic enhancer element downstream of exon 11. The mechanism of MBNL1-mediated activation of exon inclusion is unknown. We developed an in vitro splicing assay, which robustly recapitulates MBNL1-mediated splicing activation of insulin receptor exon 11 and found that MBNL1 activates removal of the intron upstream of exon 11 upon binding its functional response element in the downstream intron. MBNL1 enhances early spliceosome assembly as evidenced by enhanced complex A formation and binding of U2 small nuclear ribonucleoprotein auxiliary factor 65 kDa subunit (U2AF65) on the upstream intron. We demonstrated that neither the 5′ splice site nor exon 11 sequences are required for MBNL1-activated U2AF65 binding. Interestingly, the 5′ splice site is required for MBNL1-mediated activation of upstream intron removal, although MBNL1 has no effect on U1 snRNA recruitment. These results suggest that MBNL1 directly activates binding of U2AF65 to enhance upstream intron removal to ultimately activate alternative exon inclusion.
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Affiliation(s)
- Gloria V Echeverria
- Integrative Molecular and Biomedical Sciences Program, Baylor College of Medicine, Houston, TX 77030, USA, Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX 77030, USA, Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA and Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
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41
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Andres SF, Simmons JG, Mah AT, Santoro MA, Van Landeghem L, Lund PK. Insulin receptor isoform switching in intestinal stem cells, progenitors, differentiated lineages and tumors: evidence that IR-B limits proliferation. J Cell Sci 2013; 126:5645-56. [PMID: 24127567 DOI: 10.1242/jcs.132985] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Despite evidence for the impact of insulin on intestinal epithelial physiology and pathophysiology, the expression patterns, roles, and regulation of insulin receptor (IR) and IR isoforms in the intestinal epithelium are not well characterized. IR-A is thought to mediate the proliferative effects of insulin or insulin growth factors (IGFs) in fetal or cancer cells. IR-B is considered to be the metabolic receptor for insulin in specialized tissues. This study used a novel Sox9-EGFP reporter mouse that permits isolation of intestinal epithelial stem cells (IESCs), progenitors, enteroendocrine cells and differentiated lineages, the Apc(Min/+) mouse model of precancerous adenoma and normal human intestinal and colorectal cancer (CRC) cell lines. We tested the hypothesis that there is differential expression of IR-A or IR-B in stem and tumor cells versus differentiated intestinal epithelial cells (IECs) and that IR-B impacts cell proliferation. Our findings provide evidence that IR-B expression is significantly lower in highly proliferative IESCs and progenitor cells versus post-mitotic, differentiated IECs and in subconfluent and undifferentiated versus differentiated Caco-2 cells. IR-B is also reduced in Apc(Min/+) tumors and highly tumorigenic CRC cells. These differences in IR-B were accompanied by altered levels of mRNAs encoding muscleblind-like 2 (MBNL2), a known regulator of IR alternative splicing. Forced IR-B expression in subconfluent and undifferentiated Caco-2 cells reduced proliferation and increased biomarkers of differentiation. Our findings indicate that the impact of insulin on different cell types in the intestinal epithelium might differ depending on relative IR-B IR-A expression levels and provide new evidence for the roles of IR-B to limit proliferation of CRC cells.
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Affiliation(s)
- Sarah F Andres
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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42
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Panda AC, Grammatikakis I, Yoon JH, Abdelmohsen K. Posttranscriptional regulation of insulin family ligands and receptors. Int J Mol Sci 2013; 14:19202-29. [PMID: 24051403 PMCID: PMC3794829 DOI: 10.3390/ijms140919202] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 08/17/2013] [Accepted: 09/06/2013] [Indexed: 01/02/2023] Open
Abstract
Insulin system including ligands (insulin and IGFs) and their shared receptors (IR and IGFR) are critical regulators of insulin signaling and glucose homeostasis. Altered insulin system is associated with major pathological conditions like diabetes and cancer. The mRNAs encoding for these ligands and their receptors are posttranscriptionally controlled by three major groups of regulators; (i) alternative splicing regulatory factors; (ii) turnover and translation regulator RNA-binding proteins (TTR-RBPs); and (iii) non-coding RNAs including miRNAs and long non-coding RNAs (lncRNAs). In this review, we discuss the influence of these regulators on alternative splicing, mRNA stability and translation. Due to the pathological impacts of insulin system, we also discussed the possibilities of discovering new potential regulators which will improve understanding of insulin system and associated diseases.
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Affiliation(s)
- Amaresh C Panda
- Laboratory of Genetics, National Institute on Aging-Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA.
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43
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Jahromi AH, Nguyen L, Fu Y, Miller KA, Baranger AM, Zimmerman SC. A novel CUG(exp)·MBNL1 inhibitor with therapeutic potential for myotonic dystrophy type 1. ACS Chem Biol 2013; 8:1037-43. [PMID: 23480597 DOI: 10.1021/cb400046u] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Myotonic dystrophy type 1 (DM1) is caused by an expanded CUG repeat (CUG(exp)) that sequesters muscleblind-like 1 protein (MBNL1), a protein that regulates alternative splicing. CUG(exp) RNA is a validated drug target for this currently untreatable disease. Herein, we develop a bioactive small molecule (1) that targets CUG(exp) RNA and is able to inhibit the CUG(exp)·MBNL1 interaction in cells that model DM1. The core of this small molecule is based on ligand 2, which was previously reported to be active in an in vitro assay. A polyamine-derivative side chain was conjugated to this core to make it aqueous-soluble and cell-penetrable. In a DM1 cell model this conjugate was found to disperse CUG(exp) ribonuclear foci, release MBNL1, and partially reverse the mis-splicing of the insulin receptor pre-mRNA. Direct evidence for ribonuclear foci dispersion by this ligand was obtained in a live DM1 cell model using time-lapse confocal microscopy.
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Affiliation(s)
- Amin Haghighat Jahromi
- Center for Biophysics
and Computational Biology and ‡Department of Chemistry, University of Illinois, Urbana, Illinois, United States
| | - Lien Nguyen
- Center for Biophysics
and Computational Biology and ‡Department of Chemistry, University of Illinois, Urbana, Illinois, United States
| | - Yuan Fu
- Center for Biophysics
and Computational Biology and ‡Department of Chemistry, University of Illinois, Urbana, Illinois, United States
| | - Kali A. Miller
- Center for Biophysics
and Computational Biology and ‡Department of Chemistry, University of Illinois, Urbana, Illinois, United States
| | - Anne M. Baranger
- Center for Biophysics
and Computational Biology and ‡Department of Chemistry, University of Illinois, Urbana, Illinois, United States
| | - Steven C. Zimmerman
- Center for Biophysics
and Computational Biology and ‡Department of Chemistry, University of Illinois, Urbana, Illinois, United States
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44
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Cohen-Eliav M, Golan-Gerstl R, Siegfried Z, Andersen CL, Thorsen K, Ørntoft TF, Mu D, Karni R. The splicing factor SRSF6 is amplified and is an oncoprotein in lung and colon cancers. J Pathol 2013; 229:630-9. [PMID: 23132731 DOI: 10.1002/path.4129] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 10/03/2012] [Accepted: 10/09/2012] [Indexed: 01/01/2023]
Abstract
An increasing body of evidence connects alterations in the process of alternative splicing with cancer development and progression. However, a direct role of splicing factors as drivers of cancer development is mostly unknown. We analysed the gene copy number of several splicing factors in colon and lung tumours, and found that the gene encoding for the splicing factor SRSF6 is amplified and over-expressed in these cancers. Moreover, over-expression of SRSF6 in immortal lung epithelial cells enhanced proliferation, protected them from chemotherapy-induced cell death and converted them to be tumourigenic in mice. In contrast, knock-down of SRSF6 in lung and colon cancer cell lines inhibited their tumourigenic abilities. SRSF6 up- or down-regulation altered the splicing of several tumour suppressors and oncogenes to generate the oncogenic isoforms and reduce the tumour-suppressive isoforms. Our data suggest that the splicing factor SRSF6 is an oncoprotein that regulates the proliferation and survival of lung and colon cancer cells.
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Affiliation(s)
- Michal Cohen-Eliav
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University - Hadassah Medical School, Jerusalem, Israel
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45
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Wang ET, Cody NAL, Jog S, Biancolella M, Wang TT, Treacy DJ, Luo S, Schroth GP, Housman DE, Reddy S, Lécuyer E, Burge CB. Transcriptome-wide regulation of pre-mRNA splicing and mRNA localization by muscleblind proteins. Cell 2012; 150:710-24. [PMID: 22901804 DOI: 10.1016/j.cell.2012.06.041] [Citation(s) in RCA: 365] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 04/30/2012] [Accepted: 06/20/2012] [Indexed: 11/17/2022]
Abstract
The muscleblind-like (Mbnl) family of RNA-binding proteins plays important roles in muscle and eye development and in myotonic dystrophy (DM), in which expanded CUG or CCUG repeats functionally deplete Mbnl proteins. We identified transcriptome-wide functional and biophysical targets of Mbnl proteins in brain, heart, muscle, and myoblasts by using RNA-seq and CLIP-seq approaches. This analysis identified several hundred splicing events whose regulation depended on Mbnl function in a pattern indicating functional interchangeability between Mbnl1 and Mbnl2. A nucleotide resolution RNA map associated repression or activation of exon splicing with Mbnl binding near either 3' splice site or near the downstream 5' splice site, respectively. Transcriptomic analysis of subcellular compartments uncovered a global role for Mbnls in regulating localization of mRNAs in both mouse and Drosophila cells, and Mbnl-dependent translation and protein secretion were observed for a subset of mRNAs with Mbnl-dependent localization. These findings hold several new implications for DM pathogenesis.
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Affiliation(s)
- Eric T Wang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
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46
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Coonrod LA, Lohman JR, Berglund JA. Utilizing the GAAA tetraloop/receptor to facilitate crystal packing and determination of the structure of a CUG RNA helix. Biochemistry 2012; 51:8330-7. [PMID: 23025897 DOI: 10.1021/bi300829w] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is a microsatellite expansion disorder caused by the aberrant expansion of CTG repeats in the 3'-untranslated region of the DMPK gene. When transcribed, the toxic RNA CUG repeats sequester RNA binding proteins, which leads to disease symptoms. The expanded CUG repeats can adopt a double-stranded structure, and targeting this helix is a therapeutic strategy for DM1. To improve our understanding of the 5'CUG/3'GUC motif and how it may interact with proteins and small molecules, we designed a short CUG helix attached to a GAAA tetraloop/receptor to facilitate crystal packing. Here we report the highest-resolution structure (1.95 Å) to date of a GAAA tetraloop/receptor and the CUG helix it was used to crystallize. Within the CUG helix, we identify two different forms of noncanonical U-U pairs and reconfirm that CUG repeats are essentially A-form. An analysis of all noncanonical U-U pairs in the context of CUG repeats revealed six different classes of conformations that the noncanonical U-U pairs are able to adopt.
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Affiliation(s)
- Leslie A Coonrod
- Institute of Molecular Biology and Department of Chemistry, University of Oregon, Eugene, OR 97403, USA
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47
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Combinatorial mutagenesis of MBNL1 zinc fingers elucidates distinct classes of regulatory events. Mol Cell Biol 2012; 32:4155-67. [PMID: 22890842 DOI: 10.1128/mcb.00274-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The RNA binding protein and alternative splicing factor Muscleblind-like 1 (MBNL1) has been a topic of intense study due to its role in myotonic dystrophy (DM) pathogenesis. MBNL1 contains four zinc finger (ZF) RNA binding domains arranged in two pairs. Through combinatorial mutagenesis of the ZF domains, we demonstrate that the pairs of ZFs have differential affinity for RNA and subsequently differential splicing activities. We evaluated splicing and binding activity for six MBNL1-mediated splicing events and found that the splicing activity profiles for the ZF mutants vary among transcripts. Clustering analysis of splicing profiles revealed that two distinct classes of MBNL1 pre-mRNA substrates exist. For some of the RNA transcripts tested, binding and splicing activity of the ZF mutants correlated. However, for some transcripts it appears that MBNL1 exerts robust splicing activity in the absence of RNA binding. We demonstrate that functionally distinct classes of MBNL1-mediated splicing events exist as defined by requirements for ZF-RNA interactions.
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48
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Lukáš Z, Falk M, Feit J, Souček O, Falková I, Štefančíková L, Janoušová E, Fajkusová L, Zaorálková J, Hrabálková R. Sequestration of MBNL1 in tissues of patients with myotonic dystrophy type 2. Neuromuscul Disord 2012; 22:604-16. [DOI: 10.1016/j.nmd.2012.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Revised: 03/02/2012] [Accepted: 03/06/2012] [Indexed: 12/20/2022]
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49
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Echeverria GV, Cooper TA. RNA-binding proteins in microsatellite expansion disorders: mediators of RNA toxicity. Brain Res 2012; 1462:100-11. [PMID: 22405728 PMCID: PMC3372679 DOI: 10.1016/j.brainres.2012.02.030] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 02/02/2012] [Accepted: 02/03/2012] [Indexed: 12/22/2022]
Abstract
Although protein-mediated toxicity in neurological disease has been extensively characterized, RNA-mediated toxicity is an emerging mechanism of pathogenesis. In microsatellite expansion disorders, expansion of repeated sequences in noncoding regions gives rise to RNA that produces a toxic gain of function, while expansions in coding regions can disrupt protein function as well as produce toxic RNA. The toxic RNA typically aggregates into nuclear foci and contributes to disease pathogenesis. In many cases, toxicity of the RNA is caused by the disrupted functions of RNA-binding proteins. We will discuss evidence for RNA-mediated toxicity in microsatellite expansion disorders. Different microsatellite expansion disorders are linked with alterations in the same as well as disease-specific RNA-binding proteins. Recent studies have shown that microsatellite expansions can encode multiple repeat-containing toxic RNAs through bidirectional transcription and protein species through repeat-associated non-ATG translation. We will discuss approaches that have characterized the toxic contributions of these various factors.
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Affiliation(s)
- Gloria V. Echeverria
- Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030
| | - Thomas A. Cooper
- Department of Pathology and Immunology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030
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50
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Suzuki H, Takeuchi M, Sugiyama A, Alam AK, Vu LT, Sekiyama Y, Dam HC, Ohki SY, Tsukahara T. Alternative splicing produces structural and functional changes in CUGBP2. BMC BIOCHEMISTRY 2012; 13:6. [PMID: 22433174 PMCID: PMC3368720 DOI: 10.1186/1471-2091-13-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2011] [Accepted: 03/20/2012] [Indexed: 02/04/2023]
Abstract
Background CELF/Bruno-like proteins play multiple roles, including the regulation of alternative splicing and translation. These RNA-binding proteins contain two RNA recognition motif (RRM) domains at the N-terminus and another RRM at the C-terminus. CUGBP2 is a member of this family of proteins that possesses several alternatively spliced exons. Results The present study investigated the expression of exon 14, which is an alternatively spliced exon and encodes the first half of the third RRM of CUGBP2. The ratio of exon 14 skipping product (R3δ) to its inclusion was reduced in neuronal cells induced from P19 cells and in the brain. Although full length CUGBP2 and the CUGBP2 R3δ isoforms showed a similar effect on the inclusion of the smooth muscle (SM) exon of the ACTN1 gene, these isoforms showed an opposite effect on the skipping of exon 11 in the insulin receptor gene. In addition, examination of structural changes in these isoforms by molecular dynamics simulation and NMR spectrometry suggested that the third RRM of R3δ isoform was flexible and did not form an RRM structure. Conclusion Our results suggest that CUGBP2 regulates the splicing of ACTN1 and insulin receptor by different mechanisms. Alternative splicing of CUGBP2 exon 14 contributes to the regulation of the splicing of the insulin receptor. The present findings specifically show how alternative splicing events that result in three-dimensional structural changes in CUGBP2 can lead to changes in its biological activity.
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Affiliation(s)
- Hitoshi Suzuki
- Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology, Ishikawa 923-1292, Japan.
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