1
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Lee J, Kang H. Nucleolin Regulates Pulmonary Artery Smooth Muscle Cell Proliferation under Hypoxia by Modulating miRNA Expression. Cells 2023; 12:cells12050817. [PMID: 36899956 PMCID: PMC10000680 DOI: 10.3390/cells12050817] [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: 12/20/2022] [Revised: 03/03/2023] [Accepted: 03/04/2023] [Indexed: 03/09/2023] Open
Abstract
Hypoxia induces the abnormal proliferation of vascular smooth muscle cells (VSMCs), resulting in the pathogenesis of various vascular diseases. RNA-binding proteins (RBPs) are involved in a wide range of biological processes, including cell proliferation and responses to hypoxia. In this study, we observed that the RBP nucleolin (NCL) was downregulated by histone deacetylation in response to hypoxia. We evaluated its regulatory effects on miRNA expression under hypoxic conditions in pulmonary artery smooth muscle cells (PASMCs). miRNAs associated with NCL were assessed using RNA immunoprecipitation in PASMCs and small RNA sequencing. The expression of a set of miRNAs was increased by NCL but reduced by hypoxia-induced downregulation of NCL. The downregulation of miR-24-3p and miR-409-3p promoted PASMC proliferation under hypoxic conditions. These results clearly demonstrate the significance of NCL-miRNA interactions in the regulation of hypoxia-induced PASMC proliferation and provide insight into the therapeutic value of RBPs for vascular diseases.
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Affiliation(s)
- Jihui Lee
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 22012, Republic of Korea
| | - Hara Kang
- Division of Life Sciences, College of Life Sciences and Bioengineering, Incheon National University, Incheon 22012, Republic of Korea
- Institute for New Drug Development, Incheon National University, Incheon 22012, Republic of Korea
- Correspondence: ; Tel.: +82-32-835-8238; Fax: +82-32-835-0763
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2
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Zhang N, Hu Q, Sui T, Fu L, Zhang X, Wang Y, Zhu X, Huang B, Lu J, Li Z, Zhang Y. Unique progerin C-terminal peptide ameliorates Hutchinson-Gilford progeria syndrome phenotype by rescuing BUBR1. NATURE AGING 2023; 3:185-201. [PMID: 36743663 PMCID: PMC10154249 DOI: 10.1038/s43587-023-00361-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 01/04/2023] [Indexed: 04/30/2023]
Abstract
An accumulating body of evidence indicates an association between mitotic defects and the aging process in Hutchinson-Gilford progeria syndrome (HGPS), which is a premature aging disease caused by progerin accumulation. Here, we found that BUBR1, a core component of the spindle assembly checkpoint, was downregulated during HGPS cellular senescence. The remaining BUBR1 was anchored to the nuclear membrane by binding with the C terminus of progerin, thus further limiting the function of BUBR1. Based on this, we established a unique progerin C-terminal peptide (UPCP) that effectively blocked the binding of progerin and BUBR1 and enhanced the expression of BUBR1 by interfering with the interaction between PTBP1 and progerin. Finally, UPCP significantly inhibited HGPS cellular senescence and ameliorated progeroid phenotypes, extending the lifespan of LmnaG609G/G609G mice. Our findings reveal an essential role for the progerin-PTBP1-BUBR1 axis in HGPS. Therapeutics designed around UPCP may be a beneficial strategy for HGPS treatment.
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Affiliation(s)
- Na Zhang
- Key Laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Qianying Hu
- Key Laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Tingting Sui
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Lu Fu
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
| | - Xinglin Zhang
- Key Laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Yu Wang
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China
| | - Xiaojuan Zhu
- Key Laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Baiqu Huang
- Key Laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, China
| | - Jun Lu
- Institute of Genetics and Cytology, Northeast Normal University, Changchun, China.
| | - Zhanjun Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China.
| | - Yu Zhang
- Key Laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, China.
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3
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Dai S, Wang C, Zhang C, Feng L, Zhang W, Zhou X, He Y, Xia X, Chen B, Song W. PTB: Not just a polypyrimidine tract-binding protein. J Cell Physiol 2022; 237:2357-2373. [PMID: 35288937 DOI: 10.1002/jcp.30716] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 02/19/2022] [Accepted: 02/22/2022] [Indexed: 01/21/2023]
Abstract
Polypyrimidine tract-binding protein (PTB), as a member of the heterogeneous nuclear ribonucleoprotein family, functions by rapidly shuttling between the nucleus and the cytoplasm. PTB is involved in the alternative splicing of pre-messenger RNA (mRNA) and almost all steps of mRNA metabolism. PTB regulation is organ-specific; brain- or muscle-specific microRNAs and long noncoding RNAs partially contribute to regulating PTB, thereby modulating many physiological and pathological processes, such as embryonic development, cell development, spermatogenesis, and neuron growth and differentiation. Previous studies have shown that PTB knockout can inhibit tumorigenesis and development. The knockout of PTB in glial cells can be reprogrammed into functional neurons, which shows great promise in the field of nerve regeneration but is controversial.
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Affiliation(s)
- Shirui Dai
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China.,Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, P. R. China
| | - Chao Wang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Cheng Zhang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Lemeng Feng
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Wulong Zhang
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Xuezhi Zhou
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Ye He
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Xiaobo Xia
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
| | - Baihua Chen
- Department of Ophthalmology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Clinical Research Center of Ophthalmic Disease, Changsha, Hunan, P. R. China
| | - Weitao Song
- National Clinical Research Center for Geriatric Diseases, Xiangya Hospital of Central South University, Changsha, Hunan, P. R. China.,Eye Center of Xiangya Hospital, Central South University, Changsha, Hunan, P. R. China.,Hunan Key Laboratory of Ophthalmology, Changsha, Hunan, P. R. China
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4
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Zeng P, Hua QH, Gong JY, Shi CJ, Pi XP, Xie X, Zhang R. Neonatal cortical astrocytes possess intrinsic potential in neuronal conversion in defined media. Acta Pharmacol Sin 2021; 42:1757-1768. [PMID: 33547374 PMCID: PMC8563807 DOI: 10.1038/s41401-020-00586-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 11/19/2020] [Indexed: 01/30/2023] Open
Abstract
Astrocytes are multifunctional brain cells responsible for maintaining the health and function of the central nervous system. Accumulating evidence suggests that astrocytes might be complementary source across different brain regions to supply new neurons during adult neurogenesis. In this study, we found that neonatal mouse cortical astrocytes can be directly converted into neurons when exposed to neurogenic differentiation culture conditions, with insulin being the most critical component. Detailed comparison studies between mouse cortical astrocytes and neuronal progenitor cells (NPCs) demonstrated the converted neuronal cells originate indeed from the astrocytes rather than NPCs. The neurons derived from mouse cortical astrocytes display typical neuronal morphologies, express neuronal markers and possess typical neuronal electrophysiological properties. More importantly, these neurons can survive and mature in the mouse brain in vivo. Finally, by comparing astrocytes from different brain regions, we found that only cortical astrocytes but not astrocytes from other brain regions such as hippocampus and cerebellum can be converted into neurons under the current condition. Altogether, our findings suggest that neonatal astrocytes from certain brain regions possess intrinsic potential to differentiate/transdifferentiate into neurons which may have clinical relevance in the future.
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Affiliation(s)
- Peng Zeng
- grid.24516.340000000123704535Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, Collaborative Innovation Center for Brain Science, School of Life Sciences and Technology, Tongji University, Shanghai, 200092 China
| | - Qiu-hong Hua
- grid.24516.340000000123704535Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, Collaborative Innovation Center for Brain Science, School of Life Sciences and Technology, Tongji University, Shanghai, 200092 China
| | - Jun-yuan Gong
- grid.24516.340000000123704535Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, Collaborative Innovation Center for Brain Science, School of Life Sciences and Technology, Tongji University, Shanghai, 200092 China
| | - Chang-jie Shi
- grid.24516.340000000123704535Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, Collaborative Innovation Center for Brain Science, School of Life Sciences and Technology, Tongji University, Shanghai, 200092 China
| | - Xiao-ping Pi
- grid.9227.e0000000119573309CAS Key Laboratory of Receptor Research, the National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203 China
| | - Xin Xie
- grid.9227.e0000000119573309CAS Key Laboratory of Receptor Research, the National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203 China
| | - Ru Zhang
- grid.24516.340000000123704535Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, Collaborative Innovation Center for Brain Science, School of Life Sciences and Technology, Tongji University, Shanghai, 200092 China
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5
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Dynamic Variations of 3'UTR Length Reprogram the mRNA Regulatory Landscape. Biomedicines 2021; 9:biomedicines9111560. [PMID: 34829789 PMCID: PMC8615635 DOI: 10.3390/biomedicines9111560] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/10/2021] [Accepted: 10/15/2021] [Indexed: 12/16/2022] Open
Abstract
This paper concerns 3′-untranslated regions (3′UTRs) of mRNAs, which are non-coding regulatory platforms that control stability, fate and the correct spatiotemporal translation of mRNAs. Many mRNAs have polymorphic 3′UTR regions. Controlling 3′UTR length and sequence facilitates the regulation of the accessibility of functional effectors (RNA binding proteins, miRNAs or other ncRNAs) to 3′UTR functional boxes and motifs and the establishment of different regulatory landscapes for mRNA function. In this context, shortening of 3′UTRs would loosen miRNA or protein-based mechanisms of mRNA degradation, while 3′UTR lengthening would strengthen accessibility to these effectors. Alterations in the mechanisms regulating 3′UTR length would result in widespread deregulation of gene expression that could eventually lead to diseases likely linked to the loss (or acquisition) of specific miRNA binding sites. Here, we will review the mechanisms that control 3′UTR length dynamics and their alterations in human disorders. We will discuss, from a mechanistic point of view centered on the molecular machineries involved, the generation of 3′UTR variability by the use of alternative polyadenylation and cleavage sites, of mutually exclusive terminal alternative exons (exon skipping) as well as by the process of exonization of Alu cassettes to generate new 3′UTRs with differential functional features.
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6
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Ontiveros RJ, Hernandez L, Nguyen H, Hernandez Lopez AL, Shankar A, Kim E, Keppetipola NM. Identification and Characterization of a Minimal Functional Splicing Regulatory Protein, PTBP1. Biochemistry 2020; 59:4766-4774. [PMID: 33284593 DOI: 10.1021/acs.biochem.0c00664] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polypyrimidine tract binding protein 1 (PTBP1) is a well-studied RNA binding protein that serves as an important model for understanding molecular mechanisms underlying alternative splicing regulation. PTBP1 has four RNA binding domains (RBDs) connected via linker regions. Additionally, PTBP1 has an N-terminal unstructured region that contains nuclear import and export sequences. Each RBD can bind to pyrimidine rich elements with high affinity to mediate splicing activity. Studies support a variety of models for how PTBP1 can mediate splicing regulation on target exons. Obtaining a detailed atomic view hinges on determining a crystal structure of PTBP1 bound to a target RNA transcript. Here, we created a minimal functional PTBP1 with deletions in both linker 1 and linker 2 regions and assayed for activity on certain regulated exons, including the c-Src N1 exon. We show that for a subset of PTBP1-regulated exons the linker regions are not necessary for splicing repression activity. Gel mobility shift assays reveal the linker deletion mutant binds with 12-fold higher affinity to a target RNA sequence compared to wild-type PTBP1. A minimal PTBP1 that also contains an N-terminal region deletion binds to a target RNA with an affinity higher than that of wild-type PTBP1. Moreover, this minimal protein oligomerizes readily to form a distinct higher-order complex previously shown to be required for mediating splicing repression. This minimal functional PTBP1 protein can serve as a candidate for future structure studies to understand the mechanism of splicing repression for certain regulated exons.
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Affiliation(s)
- Robert J Ontiveros
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Luis Hernandez
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Haylena Nguyen
- Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, California 92831, United States
| | - Adrian Lino Hernandez Lopez
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, California 90035, United States
| | - Archana Shankar
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Enoch Kim
- Department of Biological Sciences, California State University Fullerton, Fullerton, California 92831, United States
| | - Niroshika M Keppetipola
- Department of Chemistry and Biochemistry, California State University Fullerton, Fullerton, California 92831, United States
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7
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Moss ND, Sussel L. mRNA Processing: An Emerging Frontier in the Regulation of Pancreatic β Cell Function. Front Genet 2020; 11:983. [PMID: 33088281 PMCID: PMC7490333 DOI: 10.3389/fgene.2020.00983] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/03/2020] [Indexed: 01/04/2023] Open
Abstract
Robust endocrine cell function, particularly β cell function, is required to maintain blood glucose homeostasis. Diabetes can result from the loss or dysfunction of β cells. Despite decades of clinical and basic research, the precise regulation of β cell function and pathogenesis in diabetes remains incompletely understood. In this review, we highlight RNA processing of mRNAs as a rapidly emerging mechanism regulating β cell function and survival. RNA-binding proteins (RBPs) and RNA modifications are primed to be the next frontier to explain many of the poorly understood molecular processes that regulate β cell formation and function, and provide an exciting potential for the development of novel therapeutics. Here we outline the current understanding of β cell specific functions of several characterized RBPs, alternative splicing events, and transcriptome wide changes in RNA methylation. We also highlight several RBPs that are dysregulated in both Type 1 and Type 2 diabetes, and discuss remaining knowledge gaps in the field.
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Affiliation(s)
- Nicole D Moss
- Cell, Stem Cells, and Development Graduate Program, Department of Pediatrics, Barbara Davis Center, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, United States
| | - Lori Sussel
- Cell, Stem Cells, and Development Graduate Program, Department of Pediatrics, Barbara Davis Center, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, United States
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8
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Das D, Das A, Sahu M, Mishra SS, Khan S, Bejugam PR, Rout PK, Das A, Bano S, Mishra GP, Raghav SK, Dixit A, Panda AC. Identification and Characterization of Circular Intronic RNAs Derived from Insulin Gene. Int J Mol Sci 2020; 21:ijms21124302. [PMID: 32560282 PMCID: PMC7352490 DOI: 10.3390/ijms21124302] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/02/2020] [Accepted: 06/09/2020] [Indexed: 01/09/2023] Open
Abstract
Circular RNAs (circRNAs) are a large family of noncoding RNAs that have emerged as novel regulators of gene expression. However, little is known about the function of circRNAs in pancreatic β-cells. Here, transcriptomic analysis of mice pancreatic islet RNA-sequencing data identified 77 differentially expressed circRNAs between mice fed with a normal diet and a high-fat diet. Surprisingly, multiple circRNAs were derived from the intron 2 of the preproinsulin 2 (Ins2) gene and are termed as circular intronic (ci)-Ins2. The expression of ci-Ins2 transcripts in mouse pancreatic islets, and βTC6 cells were confirmed by reverse transcription PCR, DNA sequencing, and RNase R treatment experiments. The level of ci-Ins2 was altered in βTC6 cells upon exposure to elevated levels of palmitate and glucose. Computational analysis predicted the interaction of several RNA-binding proteins with ci-Ins2 and their flanking region, suggesting their role in the ci-Ins2 function or biogenesis. Additionally, bioinformatics analysis predicted the association of several microRNAs with ci-Ins2. Gene ontology and pathway analysis of genes targeted by miRNAs associated with ci-Ins2 suggested the regulation of several key biological processes. Together, our findings indicate that differential expression of circRNAs, especially ci-Ins2 transcripts, may regulate β-cell function and may play a critical role in the development of diabetes.
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Affiliation(s)
- Debojyoti Das
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha 751024, India
| | - Aniruddha Das
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha 751024, India
| | - Mousumi Sahu
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Smruti Sambhav Mishra
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Shaheerah Khan
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Pruthvi R. Bejugam
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Pranita K. Rout
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Arundhati Das
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
- School of Biotechnology, KIIT University, Bhubaneswar, Odisha 751024, India
| | - Shehnaz Bano
- National Center for Cell Sciences (NCCS), Pune, Maharashtra 411007, India;
| | - Gyan Prakash Mishra
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Sunil K. Raghav
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Anshuman Dixit
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
| | - Amaresh C. Panda
- Institute of Life Sciences (ILS), Nalco Square, Bhubaneswar, Odisha 751023, India; (D.D.); (A.D.); (M.S.); (S.S.M.); (S.K.); (P.R.B.); (P.K.R.); (A.D.); (G.P.M.); (S.K.R.); (A.D.)
- Correspondence: ; Tel.: +91-674-230-43-14
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9
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Li Z, Zhou M, Cai Z, Liu H, Zhong W, Hao Q, Cheng D, Hu X, Hou J, Xu P, Xue Y, Zhou Y, Xu T. RNA-binding protein DDX1 is responsible for fatty acid-mediated repression of insulin translation. Nucleic Acids Res 2019; 46:12052-12066. [PMID: 30295850 PMCID: PMC6294501 DOI: 10.1093/nar/gky867] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 09/14/2018] [Indexed: 01/13/2023] Open
Abstract
The molecular mechanism in pancreatic β cells underlying hyperlipidemia and insulin insufficiency remains unclear. Here, we find that the fatty acid-induced decrease in insulin levels occurs due to a decrease in insulin translation. Since regulation at the translational level is generally mediated through RNA-binding proteins, using RNA antisense purification coupled with mass spectrometry, we identify a novel insulin mRNA-binding protein, namely, DDX1, that is sensitive to palmitate treatment. Notably, the knockdown or overexpression of DDX1 affects insulin translation, and the knockdown of DDX1 eliminates the palmitate-induced repression of insulin translation. Molecular mechanism studies show that palmitate treatment causes DDX1 phosphorylation at S295 and dissociates DDX1 from insulin mRNA, thereby leading to the suppression of insulin translation. In addition, DDX1 may interact with the translation initiation factors eIF3A and eIF4B to regulate translation. In high-fat diet mice, the inhibition of insulin translation happens at an early prediabetic stage before the elevation of glucose levels. We speculate that the DDX1-mediated repression of insulin translation worsens the situation of insulin resistance and contributes to the elevation of blood glucose levels in obese animals.
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Affiliation(s)
- Zonghong Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.,Jilin Province Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun 130024, China
| | - Maoge Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhaokui Cai
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hongyang Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Wen Zhong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Qiang Hao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Dongwan Cheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Xihao Hu
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Junjie Hou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingyong Xu
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuanchao Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yifa Zhou
- Jilin Province Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun 130024, China
| | - Tao Xu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
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10
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Taniguchi K, Sakai M, Sugito N, Kumazaki M, Shinohara H, Yamada N, Nakayama T, Ueda H, Nakagawa Y, Ito Y, Futamura M, Uno B, Otsuki Y, Yoshida K, Uchiyama K, Akao Y. PTBP1-associated microRNA-1 and -133b suppress the Warburg effect in colorectal tumors. Oncotarget 2017; 7:18940-52. [PMID: 26980745 PMCID: PMC4951342 DOI: 10.18632/oncotarget.8005] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/05/2016] [Indexed: 01/24/2023] Open
Abstract
It is known that pyruvate kinase in muscle (PKM), which is a rate-limiting glycolytic enzyme, has essential roles in the Warburg effect and that expression of cancer-dominant PKM2 is increased by polypyrimidine tract-binding protein 1 (PTBP1), which is a splicer of the PKM gene. In other words, PKM2 acts as a promoter of the Warburg effect. Previously, we demonstrated that the Warburg effect was partially established by down-regulation of several microRNAs (miRs) that bind to PTBP1 and that ectopic expression of these miRs suppressed the Warburg effect. In this study, we investigated the functions of miR-1 and -133b, which are well known as muscle-specific miRs, from the viewpoint of the Warburg effect in colorectal tumors. The expression levels of miR-1 and -133b were relatively high in colon tissue except muscle and very frequently down-regulated in 75 clinical colorectal tumors samples, even in adenomas, compared with those of the adjacent normal tissue samples. The ectopic expression of these miRs induced growth suppression and autophagic cell death through the switching of PKM isoform expression from PKM2 to PKM1 by silencing PTBP1 expression both in vitro and in vivo. Also, we showed that the resultant increase in the intracellular level of reactive oxygen species (ROS) was involved in this mechanism. Furthermore, PTBP1 was highly expressed in most of the 30 clinical colorectal tumor samples examined, even in adenomas. Our results suggested that PTBP1 and PTBP1-associated miR-1 and -133b are crucial molecules for the maintenance of the Warburg effect in colorectal tumors.
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Affiliation(s)
- Kohei Taniguchi
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan.,Department of General and Gastroenterological Surgery, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan
| | - Miku Sakai
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Nobuhiko Sugito
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Minami Kumazaki
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Haruka Shinohara
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Nami Yamada
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Tatsushi Nakayama
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Hiroshi Ueda
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Yoshihito Nakagawa
- Department of Gastroenterology, Fujita Health University, School of Medicine, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
| | - Yuko Ito
- Department of Anatomy and Cell Biology, Division of Life Sciences, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan
| | - Manabu Futamura
- Department of Oncological Surgery, Gifu University School of Medicine, Gifu 501-1193, Japan
| | - Bunji Uno
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
| | - Yoshinori Otsuki
- Department of Anatomy and Cell Biology, Division of Life Sciences, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan
| | - Kazuhiro Yoshida
- Department of Oncological Surgery, Gifu University School of Medicine, Gifu 501-1193, Japan
| | - Kazuhisa Uchiyama
- Department of General and Gastroenterological Surgery, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan
| | - Yukihiro Akao
- United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu 501-1193, Japan
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11
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Nam H, Jones D, Cooksey RC, Gao Y, Sink S, Cox J, McClain DA. Synergistic Inhibitory Effects of Hypoxia and Iron Deficiency on Hepatic Glucose Response in Mouse Liver. Diabetes 2016; 65:1521-33. [PMID: 26993063 PMCID: PMC4878425 DOI: 10.2337/db15-0580] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 03/05/2016] [Indexed: 01/28/2023]
Abstract
Hypoxia and iron both regulate metabolism through multiple mechanisms, including hypoxia-inducible transcription factors. The hypoxic effects on glucose disposal and glycolysis are well established, but less is known about the effects of hypoxia and iron deficiency on hepatic gluconeogenesis. We therefore assessed their effects on hepatic glucose production in mice. Weanling C57BL/6 male mice were fed an iron-deficient (4 ppm) or iron-adequate (35 ppm) diet for 14 weeks and were continued in normoxia or exposed to hypoxia (8% O2) for the last 4 weeks of that period. Hypoxic mice became hypoglycemic and displayed impaired hepatic glucose production after a pyruvate challenge, an effect accentuated by an iron-deficient diet. Stabilization of hypoxia-inducible factors under hypoxia resulted in most glucose being converted into lactate and not oxidized. Hepatic pyruvate concentrations were lower in hypoxic mice. The decreased hepatic pyruvate levels were not caused by increased utilization but rather were contributed to by decreased metabolism from gluconeogenic amino acids. Pyruvate carboxylase, which catalyzes the first step of gluconeogenesis, was also downregulated by hypoxia with iron deficiency. Hypoxia, and more so hypoxia with iron deficiency, results in hypoglycemia due to decreased levels of hepatic pyruvate and decreased pyruvate utilization for gluconeogenesis. These data highlight the role of iron levels as an important determinant of glucose metabolism in hypoxia.
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Affiliation(s)
- Hyeyoung Nam
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Deborah Jones
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Robert C Cooksey
- Department of Internal Medicine, University of Utah, Salt Lake City, UT
| | - Yan Gao
- Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC
| | - Sandy Sink
- Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC
| | - James Cox
- Department of Biochemistry, University of Utah, Salt Lake City, UT
| | - Donald A McClain
- Department of Internal Medicine, University of Utah, Salt Lake City, UT Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC Department of Biochemistry, University of Utah, Salt Lake City, UT
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12
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Shih H, Lin CC. Tuning stiffness of cell-laden hydrogel via host–guest interactions. J Mater Chem B 2016; 4:4969-4974. [PMID: 32264023 DOI: 10.1039/c6tb00890a] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We report a dynamic hydrogel system with on-demand tunable matrix stiffness.
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Affiliation(s)
- Han Shih
- Weldon School of Biomedical Engineering
- Purdue University
- West Lafayette
- USA
| | - Chien-Chi Lin
- Weldon School of Biomedical Engineering
- Purdue University
- West Lafayette
- USA
- Department of Biomedical Engineering
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13
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Marnef A, Jády BE, Kiss T. Human polypyrimidine tract-binding protein interacts with mitochondrial tRNA(Thr) in the cytosol. Nucleic Acids Res 2015; 44:1342-53. [PMID: 26657638 PMCID: PMC4756820 DOI: 10.1093/nar/gkv1355] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 11/22/2015] [Indexed: 11/12/2022] Open
Abstract
Human polypyrimidine tract-binding protein PTB is a multifunctional RNA-binding protein with four RNA recognition motifs (RRM1 to RRM4). PTB is a nucleocytoplasmic shuttle protein that functions as a key regulator of alternative pre-mRNA splicing in the nucleoplasm and promotes internal ribosome entry site-mediated translation initiation of viral and cellular mRNAs in the cytoplasm. Here, we demonstrate that PTB and its paralogs, nPTB and ROD1, specifically interact with mitochondrial (mt) tRNA(Thr) both in human and mouse cells. In vivo and in vitro RNA-binding experiments demonstrate that PTB forms a direct interaction with the T-loop and the D-stem-loop of mt tRNA(Thr) using its N-terminal RRM1 and RRM2 motifs. RNA sequencing and cell fractionation experiments show that PTB associates with correctly processed and internally modified, mature mt tRNA(Thr) in the cytoplasm outside of mitochondria. Consistent with this, PTB activity is not required for mt tRNA(Thr) biogenesis or for correct mitochondrial protein synthesis. PTB association with mt tRNA(Thr) is largely increased upon induction of apoptosis, arguing for a potential role of the mt tRNA(Thr)/PTB complex in apoptosis. Our results lend strong support to the recently emerging conception that human mt tRNAs can participate in novel cytoplasmic processes independent from mitochondrial protein synthesis.
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Affiliation(s)
- Aline Marnef
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Beáta E Jády
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France
| | - Tamás Kiss
- Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, CNRS, Université Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 9, France Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
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14
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Ptbp1 and Exosc9 knockdowns trigger skin stability defects through different pathways. Dev Biol 2015; 409:489-501. [PMID: 26546114 DOI: 10.1016/j.ydbio.2015.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 09/14/2015] [Accepted: 11/02/2015] [Indexed: 10/22/2022]
Abstract
In humans, genetic diseases affecting skin integrity (genodermatoses) are generally caused by mutations in a small number of genes that encode structural components of the dermal-epidermal junctions. In this article, we first show that inactivation of both exosc9, which encodes a component of the RNA exosome, and ptbp1, which encodes an RNA-binding protein abundant in Xenopus embryonic skin, impairs embryonic Xenopus skin development, with the appearance of dorsal blisters along the anterior part of the fin. However, histological and electron microscopy analyses revealed that the two phenotypes are distinct. Exosc9 morphants are characterized by an increase in the apical surface of the goblet cells, loss of adhesion between the sensorial and peridermal layers, and a decrease in the number of ciliated cells within the blisters. Ptbp1 morphants are characterized by an altered goblet cell morphology. Gene expression profiling by deep RNA sequencing showed that the expression of epidermal and genodermatosis-related genes is also differentially affected in the two morphants, indicating that alterations in post-transcriptional regulations can lead to skin developmental defects through different routes. Therefore, the developing larval epidermis of Xenopus will prove to be a useful model for dissecting the post-transcriptional regulatory network involved in skin development and stability with significant implications for human diseases.
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15
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Hepatic branch vagus nerve plays a critical role in the recovery of post-ischemic glucose intolerance and mediates a neuroprotective effect by hypothalamic orexin-A. PLoS One 2014; 9:e95433. [PMID: 24759941 PMCID: PMC3997366 DOI: 10.1371/journal.pone.0095433] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/26/2014] [Indexed: 12/22/2022] Open
Abstract
Orexin-A (a neuropeptide in the hypothalamus) plays an important role in many physiological functions, including the regulation of glucose metabolism. We have previously found that the development of post-ischemic glucose intolerance is one of the triggers of ischemic neuronal damage, which is suppressed by hypothalamic orexin-A. Other reports have shown that the communication system between brain and peripheral tissues through the autonomic nervous system (sympathetic, parasympathetic and vagus nerve) is important for maintaining glucose and energy metabolism. The aim of this study was to determine the involvement of the hepatic vagus nerve on hypothalamic orexin-A-mediated suppression of post-ischemic glucose intolerance development and ischemic neuronal damage. Male ddY mice were subjected to middle cerebral artery occlusion (MCAO) for 2 h. Intrahypothalamic orexin-A (5 pmol/mouse) administration significantly suppressed the development of post-ischemic glucose intolerance and neuronal damage on day 1 and 3, respectively after MCAO. MCAO-induced decrease of hepatic insulin receptors and increase of hepatic gluconeogenic enzymes on day 1 after was reversed to control levels by orexin-A. This effect was reversed by intramedullary administration of the orexin-1 receptor antagonist, SB334867, or hepatic vagotomy. In the medulla oblongata, orexin-A induced the co-localization of cholin acetyltransferase (cholinergic neuronal marker used for the vagus nerve) with orexin-1 receptor and c-Fos (activated neural cells marker). These results suggest that the hepatic branch vagus nerve projecting from the medulla oblongata plays an important role in the recovery of post-ischemic glucose intolerance and mediates a neuroprotective effect by hypothalamic orexin-A.
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16
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He X, Arslan AD, Ho TT, Yuan C, Stampfer MR, Beck WT. Involvement of polypyrimidine tract-binding protein (PTBP1) in maintaining breast cancer cell growth and malignant properties. Oncogenesis 2014; 3:e84. [PMID: 24418892 PMCID: PMC3940912 DOI: 10.1038/oncsis.2013.47] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/13/2013] [Accepted: 11/14/2013] [Indexed: 12/12/2022] Open
Abstract
We have investigated some roles of splicing factor polypyrimidine tract-binding protein (PTBP1) in human breast cancer. We found that PTBP1 was upregulated in progressively transformed human mammary epithelial cells (HMECs), as well as in breast tumor cell lines compared with HMECs with finite growth potential and found that the level of PTBP1 correlated with the transformation state of HMECs. Knockdown of PTBP1 expression substantially inhibited tumor cell growth, colony formation in soft agar and in vitro invasiveness of breast cancer cell lines, a result similar to what we have reported in ovarian cancer. However, ectopic expression of PTBP1 (as a PTBP1-EGFP fusion protein) did not enhance the proliferation of immortalized HMEC. Rather, PTBP1 expression promoted anchorage-independent growth of an immortalized HMEC as assessed by increased colony formation in soft agar. In addition, we found that knockdown of PTBP1 expression led to upregulation of the expression of the M1 isoform of pyruvate kinase (PKM1) and increase of the ratio of PKM1 vs PKM2. PKM1 has been reported to promote oxidative phosphorylation and reduce tumorigenesis. Correspondingly, we observed increased oxygen consumption in PTBP1-knockdown breast cancer cells. Together, these results suggest that PTBP1 is associated with breast tumorigenesis and appears to be required for tumor cell growth and maintenance of transformed properties. PTBP1 exerts these effects, in part, by regulating the splicing of pyruvate kinase, and consequently alters glucose metabolism and contributes to the Warburg effect.
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Affiliation(s)
- X He
- 1] Department of Biopharmaceutical Sciences, College of Pharmacy-Rockford, University of Illinois at Chicago, Rockford, IL, USA [2] Cancer Center, University of Illinois, Chicago, IL, USA
| | - A D Arslan
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - T-T Ho
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - C Yuan
- Department of Biopharmaceutical Sciences, College of Pharmacy-Rockford, University of Illinois at Chicago, Rockford, IL, USA
| | - M R Stampfer
- Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - W T Beck
- 1] Cancer Center, University of Illinois, Chicago, IL, USA [2] Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
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17
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Geng X, Feng J, Liu S, Wang Y, Arias C, Liu Z. Transcriptional regulation of hypoxia inducible factors alpha (HIF-α) and their inhibiting factor (FIH-1) of channel catfish (Ictalurus punctatus) under hypoxia. Comp Biochem Physiol B Biochem Mol Biol 2013; 169:38-50. [PMID: 24384398 DOI: 10.1016/j.cbpb.2013.12.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/22/2013] [Accepted: 12/27/2013] [Indexed: 12/22/2022]
Abstract
Hypoxia inducible factors (HIFs) are considered to be the master switch of oxygen-dependent gene expression with mammalian species. In most cases, regulation of HIF has been believed at posttranslational levels. However, little is known of HIF regulation in channel catfish, a species highly tolerant to low oxygen condition. Here we report the identification and characterization of HIF-1α, HIF-2αa, HIF-2αb, HIF-3α, and FIH-1 genes, and their mRNA expression under hypoxia conditions. The transcripts of the five genes were found to be regulated temporally and spatially after low oxygen challenge, suggesting regulation of HIF-α genes at pre-translational levels. In most tissues, the HIF-α mRNAs were down-regulated 1.5h but up-regulated 5h after hypoxia treatment. Of these HIF-α mRNAs, the expression of HIF-3α mRNA was induced in the most dramatic fashion, both in the speed of induction and the extent of induction, compared to HIF-1α and HIF-2α genes, suggesting its importance in responses to hypoxia.
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Affiliation(s)
- Xin Geng
- Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA
| | - Jianbin Feng
- Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA
| | - Shikai Liu
- Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA
| | - Yaping Wang
- Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA; Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Covadonga Arias
- Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA
| | - Zhanjiang Liu
- Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA.
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18
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Regulation of β-cell function by RNA-binding proteins. Mol Metab 2013; 2:348-55. [PMID: 24327951 DOI: 10.1016/j.molmet.2013.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 09/15/2013] [Accepted: 09/16/2013] [Indexed: 02/05/2023] Open
Abstract
β-cells of the pancreatic islets are highly specialized and high-throughput units for the production of insulin, the key hormone for maintenance of glucose homeostasis. Elevation of extracellular glucose and/or GLP-1 levels triggers a rapid upregulation of insulin biosynthesis through the activation of post-transcriptional mechanisms. RNA-binding proteins are emerging as key factors in the regulation of these mechanisms as well as in other aspects of β-cell function and glucose homeostasis at large, and thus may be implicated in the pathogenesis of diabetes. Here we review current research in the field, with a major emphasis on RNA-binding proteins that control biosynthesis of insulin and other components of the insulin secretory granules by modulating the stability and translation of their mRNAs.
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19
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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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20
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Lin S, Wang MJ, Tseng KY. Polypyrimidine tract-binding protein induces p19(Ink4d) expression and inhibits the proliferation of H1299 cells. PLoS One 2013; 8:e58227. [PMID: 23536791 PMCID: PMC3594294 DOI: 10.1371/journal.pone.0058227] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 02/01/2013] [Indexed: 11/18/2022] Open
Abstract
The expression of polypyrimidine tract-binding protein (PTB) is up-regulated in many types of cancer. Here, we studied the role of PTB in the growth of non small cell lung cancer cells. Data showed that PTB overexpression inhibited the growth of H1299 cells at least by inhibiting DNA synthesis. Quantitative real-time PCR and Western blot analyses showed that PTB overexpression in H1299 cells specifically induced the expression of p19Ink4d, an inhibitor of cyclin-dependent kinase 4. Repression of p19Ink4d expression partially rescued PTB-caused proliferation inhibition. PTB overexpression also inhibited the growth and induced the expression of p19Ink4d mRNA in A549 cells. However, Western blot analyses failed to detect the presence of p19Ink4d protein in A549 cells. To address how PTB induced p19Ink4d in H1299 cells, we showed that PTB might up-regulate the activity of p19Ink4d gene (CDKN2D) promoter. Besides, PTB lacking the RNA recognition motif 3 (RRM3) was less effective in growth inhibition and p19Ink4d induction, suggesting that RNA-binding activity of PTB plays an important role in p19Ink4d induction. However, immunoprecipitation of ribonuclearprotein complexes plus quantitative real-time PCR analyses showed that PTB might not bind p19Ink4d mRNA, suggesting that PTB overexpression might trigger the other RNA-binding protein(s) to bind p19Ink4d mRNA. Subsequently, RNA electrophoretic mobility-shift assays revealed a 300-base segment (designated as B2) within the 3′UTR of p19Ink4d mRNA, with which the cytoplasmic lysates of PTB-overexpressing cells formed more prominent complexes than did control cell lysates. Insertion of B2 into a reporter construct increased the expression of the chimeric luciferase transcripts in transfected PTB-overexpressing cells but not in control cells; conversely, overexpression of B2-containing reporter construct in PTB-overexpressing cells abolished the induction of p19Ink4d mRNA. In sum, we have shown that PTB plays as a negative regulator in H1299 cell proliferation at least by inducing p19Ink4d expression at transcriptional and post-transcriptional levels.
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Affiliation(s)
- Shankung Lin
- Institute of Cellular and System Medicine, National Health Research Institutes, Zhunan Town, Miaoli, Taiwan, Republic of China.
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21
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Xue Y, Ouyang K, Huang J, Zhou Y, Ouyang H, Li H, Wang G, Wu Q, Wei C, Bi Y, Jiang L, Cai Z, Sun H, Zhang K, Zhang Y, Chen J, Fu XD. Direct conversion of fibroblasts to neurons by reprogramming PTB-regulated microRNA circuits. Cell 2013; 152:82-96. [PMID: 23313552 DOI: 10.1016/j.cell.2012.11.045] [Citation(s) in RCA: 405] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 05/16/2012] [Accepted: 11/09/2012] [Indexed: 12/31/2022]
Abstract
The induction of pluripotency or trans-differentiation of one cell type to another can be accomplished with cell-lineage-specific transcription factors. Here, we report that repression of a single RNA binding polypyrimidine-tract-binding (PTB) protein, which occurs during normal brain development via the action of miR-124, is sufficient to induce trans-differentiation of fibroblasts into functional neurons. Besides its traditional role in regulated splicing, we show that PTB has a previously undocumented function in the regulation of microRNA functions, suppressing or enhancing microRNA targeting by competitive binding on target mRNA or altering local RNA secondary structure. A key event during neuronal induction is the relief of PTB-mediated blockage of microRNA action on multiple components of the REST complex, thereby derepressing a large array of neuronal genes, including miR-124 and multiple neuronal-specific transcription factors, in nonneuronal cells. This converts a negative feedback loop to a positive one to elicit cellular reprogramming to the neuronal lineage.
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Affiliation(s)
- Yuanchao Xue
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, China
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22
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Keppetipola N, Sharma S, Li Q, Black DL. Neuronal regulation of pre-mRNA splicing by polypyrimidine tract binding proteins, PTBP1 and PTBP2. Crit Rev Biochem Mol Biol 2012; 47:360-78. [PMID: 22655688 DOI: 10.3109/10409238.2012.691456] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Alternative splicing patterns are regulated by RNA binding proteins that assemble onto each pre-mRNA to form a complex RNP structure. The polypyrimidine tract binding protein, PTB, has served as an informative model for understanding how RNA binding proteins affect spliceosome assembly and how changes in the expression of these proteins can control complex programs of splicing in tissues. In this review, we describe the mechanisms of splicing regulation by PTB and its function, along with its paralog PTBP2, in neuronal development.
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Affiliation(s)
- Niroshika Keppetipola
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, USA
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23
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Abstract
Post-transcriptional gene regulation by microRNAs (miRNAs) and RNA-binding proteins (RBPs) is central to many biological functions. Aberrant gene expression patterns underlie many metabolic diseases that represent major public health concerns and formidable therapeutic challenges. Several studies have established a number of post-transcriptional regulators implicated in metabolic diseases such as diabetes and obesity. In addition, emerging knowledge of metabolically active and insulin-sensitive organs, such as the pancreas, liver, muscle and adipose compartment, is rapidly expanding the panel of potential therapeutic targets for the treatment of metabolic diseases. Here, we review our current understanding of miRNAs and RBPs that affect glucose and lipid homeostasis, and their roles in normal physiology and metabolic disorders, especially type 2 diabetes and obesity.
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Affiliation(s)
- Wook Kim
- Laboratory of Clinical Investigation, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD, USA
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Lee EK, Kim W, Tominaga K, Martindale JL, Yang X, Subaran SS, Carlson OD, Mercken EM, Kulkarni RN, Akamatsu W, Okano H, Perrone-Bizzozero NI, de Cabo R, Egan JM, Gorospe M. RNA-binding protein HuD controls insulin translation. Mol Cell 2012; 45:826-35. [PMID: 22387028 PMCID: PMC3319250 DOI: 10.1016/j.molcel.2012.01.016] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 11/21/2011] [Accepted: 01/03/2012] [Indexed: 11/18/2022]
Abstract
Although expression of the mammalian RNA-binding protein HuD was considered to be restricted to neurons, we report that HuD is present in pancreatic β cells, where its levels are controlled by the insulin receptor pathway. We found that HuD associated with a 22-nucleotide segment of the 5' untranslated region (UTR) of preproinsulin (Ins2) mRNA. Modulating HuD abundance did not alter Ins2 mRNA levels, but HuD overexpression decreased Ins2 mRNA translation and insulin production, and conversely, HuD silencing enhanced Ins2 mRNA translation and insulin production. Following treatment with glucose, HuD rapidly dissociated from Ins2 mRNA and enabled insulin biosynthesis. Importantly, HuD-knockout mice displayed higher insulin levels in pancreatic islets, while HuD-overexpressing mice exhibited lower insulin levels in islets and in plasma. In sum, our results identify HuD as a pivotal regulator of insulin translation in pancreatic β cells.
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Affiliation(s)
- Eun Kyung Lee
- Laboratory of Molecular Biology and Immunology, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
- Department of Biochemistry, College of Medicine, The Catholic University of Korea, Seoul 137-701, South Korea
| | - Wook Kim
- Laboratory of Clinical Investigation, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Kumiko Tominaga
- Laboratory of Molecular Biology and Immunology, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Jennifer L. Martindale
- Laboratory of Molecular Biology and Immunology, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Xiaoling Yang
- Laboratory of Molecular Biology and Immunology, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Sarah S. Subaran
- Laboratory of Clinical Investigation, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Olga D. Carlson
- Laboratory of Clinical Investigation, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Evi M. Mercken
- Laboratory of Experimental Gerontology, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Rohit N. Kulkarni
- Department of Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
| | - Wado Akamatsu
- Department of Physiology, Graduate School of Medicine, Keio University, Shinjuku, Tokyo 160-8582, Japan
| | - Hideyuki Okano
- Department of Physiology, Graduate School of Medicine, Keio University, Shinjuku, Tokyo 160-8582, Japan
| | - Nora I. Perrone-Bizzozero
- Department of Neurosciences, School of Medicine, University of New Mexico, Albuquerque, NM 87131, USA
| | - Rafael de Cabo
- Laboratory of Experimental Gerontology, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Josephine M. Egan
- Laboratory of Clinical Investigation, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
| | - Myriam Gorospe
- Laboratory of Molecular Biology and Immunology, National Institute on Aging-Intramural Research Program, NIH, Baltimore, MD 21224, USA
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25
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Anju TR, Nandhu MS, Jes P, Paulose CS. Endocrine regulation of neonatal hypoxia: role of glucose, oxygen, and epinephrine supplementation. Fetal Pediatr Pathol 2011; 30:338-49. [PMID: 21846315 DOI: 10.3109/15513815.2011.587498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Responses of the endocrine system are vital in revealing the mechanisms of respiratory activities. The present study focused on changes in insulin and triiodothyronine concentration in serum, its receptors in the hearts of hypoxic neonatal rats and glucose, oxygen, and epinephrine resuscitated groups. The insulin concentration was significantly increased with a significant upregulation of receptors in hypoxic neonates. Triiodothyronine content and its receptors were significantly decreased in serum and the hearts of hypoxic neonates. The change in hormonal levels is an adaptive modification of the endocrine system to encounter the stress. The effectiveness of glucose resuscitation to hypoxic neonates was also reported.
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Affiliation(s)
- T R Anju
- Department of Biotechnology, Cochin University of Science and Technology, Cochin, India
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26
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Lee EK, Gorospe M. Minireview: posttranscriptional regulation of the insulin and insulin-like growth factor systems. Endocrinology 2010; 151:1403-8. [PMID: 20032049 PMCID: PMC2850238 DOI: 10.1210/en.2009-1123] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Insulin and IGFs share structural similarities and regulate metabolic processes including glucose homeostasis. Acute alterations in glucose levels trigger rapid changes in insulin concentration and insulin signaling. These processes are tightly regulated by posttranscriptional mechanisms that alter the stability and translation of mRNAs encoding insulin and the insulin receptor. Long-term glucose homeostasis is also modulated by IGFs and IGF receptors, whose expression is likewise subject to changes in the stability and translation of the encoding mRNAs. The control of mRNA half-life and translation is governed by RNA-binding proteins and microRNAs that interact with target transcripts at the 3' and 5' untranslated regions. In this review, we describe the RNA-binding proteins and microRNAs that target the mRNAs encoding insulin, IGFs, and their receptors. We discuss how these mRNA-binding factors help to elicit timely, versatile, and tissue-specific changes in insulin and IGF function, thereby effecting critical control of energy metabolism.
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Affiliation(s)
- Eun Kyung Lee
- National Institute on Aging-Intramural Research Program, National Institutes of Health, 251 Bayview Boulevard, Baltimore, Maryland 21224, USA
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27
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Benoit RM, Meisner NC, Kallen J, Graff P, Hemmig R, Cèbe R, Ostermeier C, Widmer H, Auer M. The X-ray Crystal Structure of the First RNA Recognition Motif and Site-Directed Mutagenesis Suggest a Possible HuR Redox Sensing Mechanism. J Mol Biol 2010; 397:1231-44. [DOI: 10.1016/j.jmb.2010.02.043] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2009] [Revised: 02/22/2010] [Accepted: 02/22/2010] [Indexed: 02/06/2023]
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28
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Clerte C, Hall KB. The domains of polypyrimidine tract binding protein have distinct RNA structural preferences. Biochemistry 2009; 48:2063-74. [PMID: 19226116 DOI: 10.1021/bi8016872] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PTB (polypyrimidine tract binding protein) participates in cellular regulatory functions in the nucleus and the cytoplasm. It binds to internal ribosome entry sites to facilitate their use in cap-independent translation. It binds to polypyrimidine tracts in pre-mRNA introns to repress inclusion of exons. It binds to the 3' untranslated regions of mRNAs to stabilize the message. These RNAs have various structures, yet PTB binds to all of them. Here, RNAs with structured or unstructured polypyrimidine tracts are bound to the full-length PTB1 protein and two protein subdomains, each containing two RNA recognition motifs. Hairpin loops from c-src and GABAA gamma2 pre-mRNAs and from the 3' terminus of hepatitis C virus (HCV) were compared to a single-stranded polypyrimidine tract from GABAA gamma2 pre-mRNA. We conclude that PTB1 RNA binding function is modular: the N-terminal RRMs preferentially bind to short (U/C) tracts displayed in loops, while the RRM3-RRM4 complex preferentially binds to longer flexible RNA sequences. Since it can bind to short and long polypyrimidine tracts, structured or single-stranded, PTB takes on the role of a versatile adaptor protein that facilitates formation of RNA-protein regulatory complexes.
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Affiliation(s)
- Caroline Clerte
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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29
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Reid DC, Chang BL, Gunderson SI, Alpert L, Thompson WA, Fairbrother WG. Next-generation SELEX identifies sequence and structural determinants of splicing factor binding in human pre-mRNA sequence. RNA (NEW YORK, N.Y.) 2009; 15:2385-2397. [PMID: 19861426 PMCID: PMC2779669 DOI: 10.1261/rna.1821809] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 09/18/2009] [Indexed: 05/28/2023]
Abstract
Many splicing factors interact with both mRNA and pre-mRNA. The identification of these interactions has been greatly improved by the development of in vivo cross-linking immunoprecipitation. However, the output carries a strong sampling bias in favor of RNPs that form on more abundant RNA species like mRNA. We have developed a novel in vitro approach for surveying binding on pre-mRNA, without cross-linking or sampling bias. Briefly, this approach entails specifically designed oligonucleotide pools that tile through a pre-mRNA sequence. The pool is then partitioned into bound and unbound fractions, which are quantified by a two-color microarray. We applied this approach to locating splicing factor binding sites in and around approximately 4000 exons. We also quantified the effect of secondary structure on binding. The method is validated by the finding that U1snRNP binds at the 5' splice site (5'ss) with a specificity that is nearly identical to the splice donor motif. In agreement with prior reports, we also show that U1snRNP appears to have some affinity for intronic G triplets that are proximal to the 5'ss. Both U1snRNP and the polypyrimidine tract binding protein (PTB) avoid exonic binding, and the PTB binding map shows increased enrichment at the polypyrimidine tract. For PTB, we confirm polypyrimidine specificity and are also able to identify structural determinants of PTB binding. We detect multiple binding motifs enriched in the PTB bound fraction of oligonucleotides. These motif combinations augment binding in vitro and are also enriched in the vicinity of exons that have been determined to be in vivo targets of PTB.
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Affiliation(s)
- Daniel C Reid
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island 02912, USA
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30
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Wang MJ, Lin S. A region within the 5'-untranslated region of hypoxia-inducible factor-1alpha mRNA mediates its turnover in lung adenocarcinoma cells. J Biol Chem 2009; 284:36500-36510. [PMID: 19887373 DOI: 10.1074/jbc.m109.008904] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Previously, we showed that CL1-5 cells express more hypoxia-inducible factor-1alpha (HIF-1alpha) than the parental CL1 cells, which bestows CL1-5 cells a stronger invasive activity. Here, we investigated the mechanisms underlying the differential expression of HIF-1alpha mRNA in CL1 and CL1-5 cells. Data showed that the transcription rate of HIF-1alpha gene in CL1 cells was slightly higher than that of CL1-5 cells, suggesting that the expression of HIF-1alpha mRNA in CL1 cells was repressed by post-transcriptional mechanisms. RNA electrophoretic mobility shift assays revealed a 61-base segment (designated as D5) within the 5'-untranslated repeat of HIF-1alpha mRNA, with which the CL1 cell lysates formed more prominent complexes (including complex I) than did CL1-5 cell lysates. Insertion of D5 into a reporter construct reduced the half-life of the chimeric transcripts in transfected CL1 but not CL1-5 cells; conversely, overexpression of D5-containing reporter construct in CL1 cells increased HIF-1alpha mRNA. We also identified the polypyrimidine tract-binding protein (PTB) as a required component of complex I. Deletion of the RNA recognition motif 1 (RRM1) or RRM3 of PTB abolished the formation of complex I. Our data showed that CL1 cells expressed more PTB than CL1-5 cells. Inhibition of PTB expression in CL1 cells decreased the formation of complex I, whereas overexpression of PTB in CL1-5 cells increased the levels of complex I, decreased the stability of HIF-1alpha and D5-containing chimeric mRNAs, and decreased cell invasiveness. In sum, we have identified in lung adenocarcinoma cells a mechanism that regulates HIF-1alpha expression by modulating HIF-1alpha mRNA stability.
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Affiliation(s)
- Ming Jen Wang
- Institute of Cellular and System Medicine, National Health Research Institutes, Number 35, Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan
| | - Shankung Lin
- Institute of Cellular and System Medicine, National Health Research Institutes, Number 35, Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan.
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31
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Abstract
In cells responding to low oxygen levels, gene expression patterns are strongly influenced by post-transcriptional processes. RNA-binding proteins (RBPs) are pivotal regulators of gene expression in response to numerous stresses, including hypoxia. Here, we review the RBPs that modulate mRNA turnover and translation in response to hypoxic challenge. The RBPs HuR (human antigen R) and PTB (polypyrimidine tract-binding protein) associate with mRNAs encoding hypoxia-response proteins such as HIF-1α and VEGF mRNAs, enhance their expression after hypoxia and play a major role in establishing hypoxic gene expression patterns. Additional RBPs such as iron-response element-binding proteins (IRPs), cytoplasmic polyadenylation-element-binding proteins (CPEBs) and several heterogeneous nuclear ribonucleoproteins (hnRNPs) also bind to hypoxia-regulated transcripts and modulate the levels of the encoded proteins. We discuss the efficient regulation of hypoxic gene expression by RBPs and the mounting interest in targeting hypoxia-regulatory RBPs in diseases with aberrant hypoxic responses.
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Affiliation(s)
- Kiyoshi Masuda
- Laboratory of Cellular and Molecular Biology, National Institute on Aging-Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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32
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Andersson A, Carlsson PO, Carlsson C, Olsson R, Nordin A, Johansson M, Palm F, Tyrberg B, Källskog O, Tillmar L, Welsh N, Mattsson G, Jansson L. Promoting islet cell function after transplantation. Cell Biochem Biophys 2009; 40:55-64. [PMID: 15289643 DOI: 10.1385/cbb:40:3:55] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Engraftment (i.e., the adaptation of transplanted pancreatic islets to their new surroundings with regard to revascularization, reinnervation, and reorganization of other stromal compartments) is of crucial importance for the survival and function of the endocrine cells. Previous studies suggest that transplantation induces both vascular and stromal dysfunctions in the implanted islets when compared with endogenous islets. Thus the vascular density and the blood perfusion of islet grafts is decreased and accompanied with a capillary hypertension. This leads to hypoxic conditions, with an associated shift toward anaerobic metabolism in grafted islets. An improved engraftment will prevent or compensate for the vascular/stromal dysfunction seen in transplanted islets and thereby augment survival of the islet implant. By such means the number of islets needed to cure the recipient will be lessened. This will increase the number of patients that can be transplanted with the limited material available.
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Affiliation(s)
- Arne Andersson
- Department of Medical Cell Biology, Biomedical Centre, Uppsala University, Uppsala, Sweden.
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33
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Ah Kim H, Lee S, Park JH, Lee S, Lee BW, Hee Ihm S, Kim TI, Wan Kim S, Soo Ko K, Lee M. Enhanced protection of Ins-1 β cells from apoptosis under hypoxia by delivery of DNA encoding secretion signal peptide-linked exendin-4. J Drug Target 2009; 17:242-8. [DOI: 10.1080/10611860902718664] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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34
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Wang S, Okamoto T. Involvement of polypyrimidine tract-binding protein (PTB)-related proteins in pollen germination in Arabidopsis. PLANT & CELL PHYSIOLOGY 2009; 50:179-190. [PMID: 19122186 DOI: 10.1093/pcp/pcn207] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The pollen grains of most angiosperms contain stores of RNAs and their translation products required for pollen germination and subsequent early elongation of pollen tubes. Polypyrimidine tract-binding protein (PTB), which is involved in the regulation of pre-mRNA alternative splicing, internal ribosomal entry site (IRES)-mediated translation and mRNA localization/sorting, is known to act as a bridging molecule between RNAs and a variety of cellular factors to fulfill cellular functions in both the nucleus and cytoplasm. Moreover, it has been reported that PTB plays roles in the differentiation and development of animal cells and tissues. In the Arabidopsis genome, there are two PTB-related genes, tentatively termed AtPTB1 and AtPTB2. In the present study, the physiological functions of AtPTBs were investigated using genetic and cytological approaches. The AtPTB promoter was highly active in vegetative cells of mature pollen grains, and AtPTB was localized in the nucleus and cytoplasm of these vegetative cells. Mutations in the AtPTB genes resulted in decreased germination efficiency, and this effect was rescued by introduction of the AtPTB2 promoter::AtPTB2-GFP. Taken together, these findings suggest that AtPTB is involved in pollen germination through possible RNA metabolism processes in late-maturing and mature pollen grains.
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Affiliation(s)
- Shuyi Wang
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Japan
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35
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Fred RG, Welsh N. The importance of RNA binding proteins in preproinsulin mRNA stability. Mol Cell Endocrinol 2009; 297:28-33. [PMID: 18621093 DOI: 10.1016/j.mce.2008.06.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 06/12/2008] [Accepted: 06/12/2008] [Indexed: 11/26/2022]
Abstract
A dynamic production of insulin is necessary for proper glucose homeostasis. In order to generate enough insulin available for exocytosis in response to the demands of the organism, the level of preproinsulin mRNA in the pancreatic beta-cell needs to fluctuate. In animal models for type 2 diabetes the contents of preproinsulin mRNA are lowered, which might suggest that an impaired metabolism of preproinsulin mRNA contributes to the development of glucose intolerance and diabetes. Thus, it is of importance to understand the mechanisms by which preproinsulin mRNA levels are regulated. Although extensively studied, there are aspects of the regulation of insulin gene expression that still remain enigmatic. Our understanding of insulin gene transcription has improved considerably the last 20 years, but less effort has been invested into the control of preproinsulin mRNA stability. The preproinsulin mRNA has a long half-life and changes in preproinsulin mRNA stability, induced by glucose, are likely to be regulated through specific mechanisms. Recent findings indicate that the polypyrimidine tract-binding protein (PTB), also named hnRNP I, by binding to the 3'-UTR (untranslated region) of the preproinsulin mRNA molecule, stabilizes the messenger, thereby participating in the glucose-induced increase in preproinsulin mRNA. This review will focus both on recent findings pertinent to PTB function in general, and on the specific role of PTB on the production of insulin in beta-cells. We will also discuss the putative co-operativity between PTB and other proteins in the control of preproinsulin mRNA stability, and review beta-cell signaling events that may control the mRNA stabilizing effect of PTB.
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Affiliation(s)
- Rikard G Fred
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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36
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Woo KC, Kim TD, Lee KH, Kim DY, Kim W, Lee KY, Kim KT. Mouse period 2 mRNA circadian oscillation is modulated by PTB-mediated rhythmic mRNA degradation. Nucleic Acids Res 2008; 37:26-37. [PMID: 19010962 PMCID: PMC2615616 DOI: 10.1093/nar/gkn893] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Circadian mRNA oscillations are the main feature of core clock genes. Among them, period 2 is a key component in negative-feedback regulation, showing robust diurnal oscillations. Moreover, period 2 has been found to have a physiological role in the cell cycle or the tumor suppression. The present study reports that 3′-untranslated region (UTR)-dependent mRNA decay is involved in the regulation of circadian oscillation of period 2 mRNA. Within the mper2 3′UTR, both the CU-rich region and polypyrimidine tract-binding protein (PTB) are more responsible for mRNA stability and degradation kinetics than are other factors. Depletion of PTB with RNAi results in mper2 mRNA stabilization. During the circadian oscillations of mper2, cytoplasmic PTB showed a reciprocal expression profile compared with mper2 mRNA and its peak amplitude was increased when PTB was depleted. This report on the regulation of mper2 proposes that post-transcriptional mRNA decay mediated by PTB is a fine-tuned regulatory mechanism that includes dampening-down effects during circadian mRNA oscillations.
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Affiliation(s)
- Kyung-Chul Woo
- Department of Life Science, Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, South Korea
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37
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Polypyrimidine-tract-binding protein: a multifunctional RNA-binding protein. Biochem Soc Trans 2008; 36:641-7. [PMID: 18631133 DOI: 10.1042/bst0360641] [Citation(s) in RCA: 241] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PTB (polypyrimidine-tract-binding protein) is a ubiquitous RNA-binding protein. It was originally identified as a protein with a role in splicing but it is now known to function in a large number of diverse cellular processes including polyadenylation, mRNA stability and translation initiation. Specificity of PTB function is achieved by a combination of changes in the cellular localization of this protein (its ability to shuttle from the nucleus to the cytoplasm is tightly controlled) and its interaction with additional proteins. These differences in location and trans-acting factor requirements account for the fact that PTB acts both as a suppressor of splicing and an activator of translation. In the latter case, the role of PTB in translation has been studied extensively and it appears that this protein is required for an alternative form of translation initiation that is mediated by a large RNA structural element termed an IRES (internal ribosome entry site) that allows the synthesis of picornaviral proteins and cellular proteins that function to control cell growth and cell death. In the present review, we discuss how PTB regulates these disparate processes.
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38
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Chaiban JT, Bitar FF, Azar ST. Effect of chronic hypoxia on leptin, insulin, adiponectin, and ghrelin. Metabolism 2008; 57:1019-22. [PMID: 18640376 DOI: 10.1016/j.metabol.2007.02.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Accepted: 02/07/2007] [Indexed: 10/21/2022]
Abstract
The endocrine system plays an important role in the adaptation to hypoxia. The aim of this study was to assess the effect of chronic hypoxia on insulin, adiponectin, leptin, and ghrelin levels in a neonatal animal model. Sprague-Dawley rats were placed in a normobaric hypoxic environment at birth. Controls remained in room air. Rats were killed at 2 and 8 weeks of life. Insulin, adiponectin, leptin, and ghrelin were measured. At 2 weeks of life, there was no significant difference in insulin, adiponectin, and leptin levels between the hypoxic and control rats. The only statistically significant difference was found in ghrelin levels, which were lower in the hypoxic group (3.19 +/- 3.35 vs 24.52 +/- 5.09 pg/mL; P < .05). At 8 weeks of life, insulin was significantly higher in the hypoxic group (0.72 +/- 0.14 vs 0.44 +/- 0.26 ng/mL; P < .05) and adiponectin was significantly lower (1257.5 +/- 789.5 vs 7817.3 +/- 8453.7 ng/mL; P < .05). Leptin and ghrelin did not show significant difference in this age group, but leptin level per body weight was higher in the hypoxic group. Finally, we conclude that 2 weeks of continuous neonatal hypoxic exposure leads to a decrease in plasma ghrelin only with no significant change in insulin, adiponectin, and leptin and that 8 weeks of hypoxia leads to a decrease in adiponectin with an increase in insulin despite a significant decrease in weight.
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Affiliation(s)
- Joumana T Chaiban
- Department of Internal Medicine, American University of Beirut-Medical Center, Beirut 11072020, Lebanon
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39
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Abstract
Insulin is a key autoantigen in the autoimmune process leading to the development of type 1 diabetes. Recent studies in both humans and mice have shown that variation in the expression of the insulin gene, in the thymus rather than the pancreas, contributes to disease susceptibility by affecting self-tolerance to insulin. These findings have brought about a paradigm-shift in our understanding of self-tolerance and autoimmunity to molecules with tissue-restricted expression, which are often the target of autoimmune disease.
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Affiliation(s)
- Alberto Pugliese
- Immunogenetics Program, Diabetes Research Institute, Miller School of Medecine, University of Miami, Miami, Florida 33136, USA.
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40
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Pautz A, Linker K, Hubrich T, Korhonen R, Altenhöfer S, Kleinert H. The Polypyrimidine Tract-binding Protein (PTB) Is Involved in the Post-transcriptional Regulation of Human Inducible Nitric Oxide Synthase Expression. J Biol Chem 2006; 281:32294-302. [PMID: 16950790 DOI: 10.1074/jbc.m603915200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human inducible nitric oxide synthase (iNOS) expression is regulated by transcriptional and post-transcriptional mechanisms. We have recently shown that the multifunctional RNA-binding proteins KH-type splicing regulatory protein and tristetraprolin are critically involved in the post-transcriptional regulation of human iNOS expression. Several reports have shown that KH-type splicing regulatory protein colocalizes with the polypyrimidine tract-binding protein (PTB), and both RNA-binding proteins seem to interact with the same mRNAs. Therefore we analyzed the involvement of PTB in human iNOS expression. In human DLD-1 cells, cytokine incubation necessary to induce iNOS expression did not change PTB localization or expression. However, intracellular binding of PTB to the human iNOS mRNA increased after cytokine stimulation. Overexpression of PTB resulted in enhanced cytokine-induced iNOS expression. Accordingly, small interfering RNA-mediated knock down of PTB reduced cytokine-dependent iNOS expression. Recombinant PTB displayed binding to an UC-rich sequence in the 3'-untranslated region of the human iNOS mRNA. Transfection experiments showed that PTB mediates its effect on iNOS expression via binding to this region. The underlying mechanism is based on a modulation of iNOS mRNA stability. In summary, human iNOS is the first example of a human pro-inflammatory gene regulated by PTB on the level of mRNA stability.
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Affiliation(s)
- Andrea Pautz
- Department of Pharmacology, Johannes Gutenberg University, Obere Zahlbacher Strasse 67, D-55101 Mainz, Germany
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41
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Lee M, Choi D, Choi MJ, Jeong JH, Kim WJ, Oh S, Kim YH, Bull DA, Kim SW. Hypoxia-inducible gene expression system using the erythropoietin enhancer and 3′-untranslated region for the VEGF gene therapy. J Control Release 2006; 115:113-9. [PMID: 16962197 DOI: 10.1016/j.jconrel.2006.07.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 07/06/2006] [Accepted: 07/13/2006] [Indexed: 01/10/2023]
Abstract
Gene therapy with the vascular endothelial growth factor (VEGF) gene is a potential treatment for many disorders or injuries with ischemia. However, unregulated expression of VEGF may induce pathological angiogenesis, promoting tumor growth, diabetic proliferative retinopathy and rupture of atherosclerotic plaque. Therefore, the effective regulation of the gene expression is one of the requirements for the VEGF gene therapy. In this research, we evaluated the hypoxia-inducible gene expression system with the erythropoietin (Epo) enhancer and the Epo 3'-untranslated region (UTR). The luciferase plasmids were constructed with the Epo enhancer (pEpo-SV-Luc), the Epo 3'-UTR (pSV-Luc-EpoUTR) or both (pEpo-SV-Luc-EpoUTR). The polyethylenimine/plasmid complexes were transfected to 293 or A7R5 cells and the cells were incubated under normoxia or hypoxia. The results showed that the Epo enhancer or Epo 3'-UTR increased the target gene expression under hypoxia. pEpo-SV-Luc-EpoUTR showed the highest luciferase expression. The VEGF expression plasmid with the Epo enhancer and 3'-UTR was also constructed. The VEGF expression by pEpo-SV-VEGF-EpoUTR showed the highest specificity of the gene expression in the hypoxic cells. The results suggest that the VEGF plasmid with the Epo enhancer and the Epo 3'-UTR may be useful for gene therapy for ischemic diseases.
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Affiliation(s)
- Minhyung Lee
- Department of Bioengineering, College of Engineering, Hanyang University, Seoul, Korea
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42
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Clerte C, Hall KB. Characterization of multimeric complexes formed by the human PTB1 protein on RNA. RNA (NEW YORK, N.Y.) 2006; 12:457-75. [PMID: 16431980 PMCID: PMC1383584 DOI: 10.1261/rna.2178406] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Accepted: 11/18/2005] [Indexed: 05/06/2023]
Abstract
Polypyrimidine tract binding protein (PTB or hnRNP I) has several known functions in eukaryotic cells, including exon exclusion during alternative splicing events, mRNA stabilization, and regulation of viral translation and replication. PTB contains four RNA Binding Domains (RBDs, or RRMs), all of which can potentially bind RNA, but their roles in the various biological functions of PTB are not clear. We investigate the properties of the complexes formed by human PTB1 on two target RNAs: the rat GABAA receptor gamma2 subunit pre-mRNA and the Hepatitis C Virus 3' NonTranslated RNA. The GABA RNA contains four polypyrimidine tracts in the intron and exon, while the HCV NTR contains a 75-nt U-rich tract and a highly structured 3'-terminus. Electrophoretic mobility shift assays show that PTB1 protein first binds to both RNAs with nanomolar affinities, but subsequent protein addition leads to formation of higher-order complexes. Stoichiometry experiments show that the ultimate complexes contain up to eight PTB1 proteins per RNA strand. Protein constructs containing two tandem RBDs also bind the two RNAs, but with different affinities and stoichiometries. Nuclease protection assays show that PTB1 protects the polypyrimidine tracts in the GABA RNA, as does a construct consisting of RBD3 and RBD4; however, a construct containing RBD1 and RBD2 enhances cleavage of bound RNA. The binding mechanisms of PTB1 are unique to the full-length protein; these modes appear to include direct association with the RNA as well as weaker intermolecular protein associations.
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Affiliation(s)
- Caroline Clerte
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA
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43
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Fred RG, Welsh N. Increased expression of polypyrimidine tract binding protein results in higher insulin mRNA levels. Biochem Biophys Res Commun 2005; 328:38-42. [PMID: 15670747 DOI: 10.1016/j.bbrc.2004.12.147] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2004] [Indexed: 11/17/2022]
Abstract
The aim of this study was to further elucidate the role of the polypyrimidine tract binding protein (PTB) in the control of insulin mRNA stability. We observed that the glucose- or interleukin-1beta-induced increase in insulin mRNA was paralleled by an increase in PTB mRNA. To further test the hypothesis that PTB controls insulin gene expression, betaTC-6 cells were treated with a PTB-specific siRNA to modify the beta-cell content of PTB. Surprisingly, we observed an increase in PTB mRNA and PTB protein levels in response to the siRNA treatment. In addition, the PTB-siRNA treatment also increased insulin mRNA. We conclude that expression of the PTB gene controls insulin production.
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Affiliation(s)
- Rikard G Fred
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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Wickenheisser JK, Nelson-Degrave VL, McAllister JM. Dysregulation of cytochrome P450 17alpha-hydroxylase messenger ribonucleic acid stability in theca cells isolated from women with polycystic ovary syndrome. J Clin Endocrinol Metab 2005; 90:1720-7. [PMID: 15598676 DOI: 10.1210/jc.2004-1860] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder characterized by ovarian hyperandrogenism. Theca interna cells isolated from the ovaries of women with PCOS are characterized by increased expression of cytochrome P450 17alpha-hydroxylase (CYP17) [steroid 17alpha-hydroxylase/17,20 lyase (P450c17)], a steroidogenic enzyme obligatory for the biosynthesis of androgens. Augmented expression of the gene encoding P450c17 (CYP17) in PCOS theca has been attributed, in part, to differential transcriptional regulation of the CYP17 promoter in normal and PCOS cells. The present studies examine whether CYP17 gene expression is also posttranscriptionally regulated at the level of mRNA stability in normal and PCOS theca cells maintained in long-term culture. Determination of endogenous CYP17 mRNA half-life by pharmacological inhibition of transcription demonstrated that the half-life of CYP17 mRNA increased 2-fold in PCOS theca cells, compared with normal theca cells. Forskolin treatment also prolonged CYP17 mRNA half-life in both normal and PCOS theca cells. In vitro mRNA degradation studies demonstrated that the 5'-untranslated region confers increased stability to CYP17 mRNA in PCOS theca cells and showed that the 5'-untranslated region of CYP17 also confers forskolin-stimulated stabilization of CYP17 mRNA. These studies indicate that a slower rate of CYP17 mRNA decay contributes to increased steady-state mRNA accumulation and augmented CYP17 gene expression in PCOS theca cells.
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Affiliation(s)
- Jessica K Wickenheisser
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, 500 University Drive H166, Hershey, Pennsylvania 17033, USA.
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45
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Simpson PJ, Monie TP, Szendröi A, Davydova N, Tyzack JK, Conte MR, Read CM, Cary PD, Svergun DI, Konarev PV, Curry S, Matthews S. Structure and RNA Interactions of the N-Terminal RRM Domains of PTB. Structure 2004; 12:1631-43. [PMID: 15341728 DOI: 10.1016/j.str.2004.07.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Revised: 05/28/2004] [Accepted: 07/06/2004] [Indexed: 11/25/2022]
Abstract
The polypyrimidine tract binding protein (PTB) is an important regulator of alternative splicing that also affects mRNA localization, stabilization, polyadenylation, and translation. NMR structural analysis of the N-terminal half of PTB (residues 55-301) shows a canonical structure for RRM1 but reveals novel extensions to the beta strands and C terminus of RRM2 that significantly modify the beta sheet RNA binding surface. Although PTB contains four RNA recognition motifs (RRMs), it is widely held that only RRMs 3 and 4 are involved in RNA binding and that RRM2 mediates homodimerization. However, we show here not only that the RRMs 1 and 2 contribute substantially to RNA binding but also that full-length PTB is monomeric, with an elongated structure determined by X-ray solution scattering that is consistent with a linear arrangement of the constituent RRMs. These new insights into the structure and RNA binding properties of PTB suggest revised models of its mechanism of action.
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Affiliation(s)
- Peter J Simpson
- Department of Biological Sciences, Imperial College, South Kensington Campus, Exhibition Road, London SW7 2AZ, UK
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Coles LS, Bartley MA, Bert A, Hunter J, Polyak S, Diamond P, Vadas MA, Goodall GJ. A multi-protein complex containing cold shock domain (Y-box) and polypyrimidine tract binding proteins forms on the vascular endothelial growth factor mRNA. Potential role in mRNA stabilization. ACTA ACUST UNITED AC 2004; 271:648-60. [PMID: 14728692 DOI: 10.1111/j.1432-1033.2003.03968.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Vascular endothelial growth factor (VEGF) is a key regulator of angiogenesis and post-transcriptional regulation plays a major role in VEGF expression. Both the 5'- and 3'-UTR are required for VEGF post-transcriptional regulation but factors binding to functional sequences within the 5'-UTR have not been fully characterized. We report here the identification of complexes, binding to the VEGFmRNA 5'- and 3'-UTR, that contain cold shock domain (CSD) and polypyrimidine tract binding (PTB) RNA binding proteins. Analysis of the CSD/PTB binding sites revealed a potential role in VEGF mRNA stability, in both noninduced and induced conditions, demonstrating a general stabilizing function. Such a stabilizing mechanism had not been reported previously for the VEGF gene. We further found that the CSD/PTB-containing complexes are large multiprotein complexes that are most likely preformed in solution and we demonstrate that PTB is associated with the VEGF mRNA in vivo. Complex formation between CSD proteins and PTB has not been reported previously. Analysis of the CSD/PTB RNA binding sites revealed a novel CSD protein RNA recognition site and also demonstrated that CSD proteins may direct the binding of CSD/PTB complexes. We found the same complexes binding to an RNA-stabilizing element of another growth factor gene, suggesting a broader functional role for the CSD/PTB complexes. Finally, as the VEGF gene is also regulated at the transcriptional level by CSD proteins, we propose a combined transcriptional/post-transcriptional role for these proteins in VEGF and other growth factor gene regulation.
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Affiliation(s)
- Leeanne S Coles
- Division of Human Immunology, The Hanson Institute, Institute of Medical and Veterinary Science, Adelaide, South Australia, Australia.
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Knoch KP, Bergert H, Borgonovo B, Saeger HD, Altkrüger A, Verkade P, Solimena M. Polypyrimidine tract-binding protein promotes insulin secretory granule biogenesis. Nat Cell Biol 2004; 6:207-14. [PMID: 15039777 DOI: 10.1038/ncb1099] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2003] [Accepted: 01/26/2004] [Indexed: 01/12/2023]
Abstract
Pancreatic beta-cells store insulin in secretory granules that undergo exocytosis upon glucose stimulation. Sustained stimulation depletes beta-cells of their granule pool, which must be quickly restored. However, the factors promoting rapid granule biogenesis are unknown. Here we show that beta-cell stimulation induces the nucleocytoplasmic translocation of polypyrimidine tract-binding protein (PTB). Activated cytosolic PTB binds and stabilizes mRNAs encoding proteins of secretory granules, thus increasing their translation, whereas knockdown of PTB expression by RNA interference (RNAi) results in the depletion of secretory granules. These findings may provide insight for the understanding and treatment of diabetes, in which insulin secretion is typically impaired.
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Affiliation(s)
- Klaus-Peter Knoch
- Experimental Diabetology, Carl Gustav Carus Medical School, University of Technology Dresden, Dresden 01307, Germany
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48
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Promoting islet cell function after transplantation. Cell Biochem Biophys 2004. [DOI: 10.1007/bf02739012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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