1
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Schlusser N, Zavolan M. On the limits of inferring biophysical parameters of RBP-RNA interactions from in vitro RNA Bind'n Seq data. F1000Res 2024; 12:742. [PMID: 39056095 PMCID: PMC11269977 DOI: 10.12688/f1000research.135164.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/08/2024] [Indexed: 07/28/2024] Open
Abstract
We develop a thermodynamic model describing the binding of RNA binding proteins (RBP) to oligomers in vitro. We apply expectation-maximization to infer the specificity of RBPs, represented as position-specific weight matrices (PWMs), by maximizing the likelihood of RNA Bind'n Seq data from the ENCODE project. Analyzing these public data we find sequence motifs that can partly explain the data for more than half of the studied 111 RBPs, and for 48 of the proteins these motifs are consistent with the known specificity. Our code is publicly available, facilitating analysis of RBP binding data.
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Affiliation(s)
- Niels Schlusser
- Biozentrum, Universitat Basel, Basel, Basel-Stadt, 4056, Switzerland
| | - Mihaela Zavolan
- Biozentrum, Universitat Basel, Basel, Basel-Stadt, 4056, Switzerland
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2
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Dar MS, Mensah IK, He M, McGovern S, Sohal IS, Whitlock HC, Bippus NE, Ceminsky M, Emerson ML, Tan HJ, Hall MC, Gowher H. Dnmt3bas coordinates transcriptional induction and alternative exon inclusion to promote catalytically active Dnmt3b expression. Cell Rep 2023; 42:112587. [PMID: 37294637 PMCID: PMC10592478 DOI: 10.1016/j.celrep.2023.112587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 03/16/2023] [Accepted: 05/16/2023] [Indexed: 06/11/2023] Open
Abstract
Embryonic expression of DNMT3B is critical for establishing de novo DNA methylation. This study uncovers the mechanism through which the promoter-associated long non-coding RNA (lncRNA) Dnmt3bas controls the induction and alternative splicing of Dnmt3b during embryonic stem cell (ESC) differentiation. Dnmt3bas recruits the PRC2 (polycomb repressive complex 2) at cis-regulatory elements of the Dnmt3b gene expressed at a basal level. Correspondingly, Dnmt3bas knockdown enhances Dnmt3b transcriptional induction, whereas overexpression of Dnmt3bas dampens it. Dnmt3b induction coincides with exon inclusion, switching the predominant isoform from the inactive Dnmt3b6 to the active Dnmt3b1. Intriguingly, overexpressing Dnmt3bas further enhances the Dnmt3b1:Dnmt3b6 ratio, attributed to its interaction with hnRNPL (heterogeneous nuclear ribonucleoprotein L), a splicing factor that promotes exon inclusion. Our data suggest that Dnmt3bas coordinates alternative splicing and transcriptional induction of Dnmt3b by facilitating the hnRNPL and RNA polymerase II (RNA Pol II) interaction at the Dnmt3b promoter. This dual mechanism precisely regulates the expression of catalytically active DNMT3B, ensuring fidelity and specificity of de novo DNA methylation.
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Affiliation(s)
- Mohd Saleem Dar
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Isaiah K Mensah
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Ming He
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Sarah McGovern
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Ikjot Singh Sohal
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA; Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | | | - Nina Elise Bippus
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Madison Ceminsky
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Martin L Emerson
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Hern J Tan
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA
| | - Mark C Hall
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Humaira Gowher
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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3
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Jiang X, Gatt A, Lashley T. HnRNP Pathologies in Frontotemporal Lobar Degeneration. Cells 2023; 12:1633. [PMID: 37371103 DOI: 10.3390/cells12121633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 06/06/2023] [Accepted: 06/09/2023] [Indexed: 06/29/2023] Open
Abstract
Frontotemporal dementia (FTD) is the second most common form of young-onset (<65 years) dementia. Clinically, it primarily manifests as a disorder of behavioural, executive, and/or language functions. Pathologically, frontotemporal lobar degeneration (FTLD) is the predominant cause of FTD. FTLD is a proteinopathy, and the main pathological proteins identified so far are tau, TAR DNA-binding protein 43 (TDP-43), and fused in sarcoma (FUS). As TDP-43 and FUS are members of the heterogeneous ribonucleic acid protein (hnRNP) family, many studies in recent years have expanded the research on the relationship between other hnRNPs and FTLD pathology. Indeed, these studies provide evidence for an association between hnRNP abnormalities and FTLD. In particular, several studies have shown that multiple hnRNPs may exhibit nuclear depletion and cytoplasmic mislocalisation within neurons in FTLD cases. However, due to the diversity and complex association of hnRNPs, most studies are still at the stage of histological discovery of different hnRNP abnormalities in FTLD. We herein review the latest studies relating hnRNPs to FTLD. Together, these studies outline an important role of multiple hnRNPs in the pathogenesis of FTLD and suggest that future research into FTLD should include the whole spectrum of this protein family.
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Affiliation(s)
- Xinwa Jiang
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London WC1N 1PJ, UK
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Ariana Gatt
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London WC1N 1PJ, UK
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Tammaryn Lashley
- Queen Square Brain Bank for Neurological Disorders, UCL Queen Square Institute of Neurology, London WC1N 1PJ, UK
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
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4
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Ye R, Hu N, Cao C, Su R, Xu S, Yang C, Zhou X, Xue Y. Capture RIC-seq reveals positional rules of PTBP1-associated RNA loops in splicing regulation. Mol Cell 2023; 83:1311-1327.e7. [PMID: 36958328 DOI: 10.1016/j.molcel.2023.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 01/10/2023] [Accepted: 02/27/2023] [Indexed: 03/25/2023]
Abstract
RNA-binding proteins (RBPs) bind at different positions of the pre-mRNA molecules to promote or reduce the usage of a particular exon. Seeking to understand the working principle of these positional effects, we develop a capture RIC-seq (CRIC-seq) method to enrich specific RBP-associated in situ proximal RNA-RNA fragments for deep sequencing. We determine hnRNPA1-, SRSF1-, and PTBP1-associated proximal RNA-RNA contacts and regulatory mechanisms in HeLa cells. Unexpectedly, the 3D RNA map analysis shows that PTBP1-associated loops in individual introns preferentially promote cassette exon splicing by accelerating asymmetric intron removal, whereas the loops spanning across cassette exon primarily repress splicing. These "positional rules" can faithfully predict PTBP1-regulated splicing outcomes. We further demonstrate that cancer-related splicing quantitative trait loci can disrupt RNA loops by reducing PTBP1 binding on pre-mRNAs to cause aberrant splicing in tumors. Our study presents a powerful method for exploring the functions of RBP-associated RNA-RNA proximal contacts in gene regulation and disease.
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Affiliation(s)
- Rong Ye
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Naijing Hu
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Changchang Cao
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ruibao Su
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shihan Xu
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou, Zhejiang 325003, China
| | - Chen Yang
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou, Zhejiang 325003, China
| | - Xiangtian Zhou
- State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou, Zhejiang 325003, China
| | - Yuanchao Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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5
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Wang J, Sun D, Wang M, Cheng A, Zhu Y, Mao S, Ou X, Zhao X, Huang J, Gao Q, Zhang S, Yang Q, Wu Y, Zhu D, Jia R, Chen S, Liu M. Multiple functions of heterogeneous nuclear ribonucleoproteins in the positive single-stranded RNA virus life cycle. Front Immunol 2022; 13:989298. [PMID: 36119073 PMCID: PMC9478383 DOI: 10.3389/fimmu.2022.989298] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/12/2022] [Indexed: 11/13/2022] Open
Abstract
The heterogeneous nuclear ribonucleoproteins (hnRNPs) are a diverse family of RNA binding proteins that are implicated in RNA metabolism, such as alternative splicing, mRNA stabilization and translational regulation. According to their different cellular localization, hnRNPs display multiple functions. Most hnRNPs were predominantly located in the nucleus, but some of them could redistribute to the cytoplasm during virus infection. HnRNPs consist of different domains and motifs that enable these proteins to recognize predetermined nucleotide sequences. In the virus-host interactions, hnRNPs specifically bind to viral RNA or proteins. And some of the viral protein-hnRNP interactions require the viral RNA or other host factors as the intermediate. Through various mechanisms, hnRNPs could regulate viral translation, viral genome replication, the switch of translation to replication and virion release. This review highlights the common features and the distinguish roles of hnRNPs in the life cycle of positive single-stranded RNA viruses.
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Affiliation(s)
- Jingming Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Di Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- *Correspondence: Anchun Cheng,
| | - Yukun Zhu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Xuming Ou
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Juan Huang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Qun Gao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Dekang Zhu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu City, China
- Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu City, China
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6
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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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7
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The methyltransferase SETD2 couples transcription and splicing by engaging mRNA processing factors through its SHI domain. Nat Commun 2021; 12:1443. [PMID: 33664260 PMCID: PMC7933334 DOI: 10.1038/s41467-021-21663-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 02/04/2021] [Indexed: 12/13/2022] Open
Abstract
Heterogeneous ribonucleoproteins (hnRNPs) are RNA binding molecules that are involved in key processes such as RNA splicing and transcription. One such hnRNP protein, hnRNP L, regulates alternative splicing (AS) by binding to pre-mRNA transcripts. However, it is unclear what factors contribute to hnRNP L-regulated AS events. Using proteomic approaches, we identified several key factors that co-purify with hnRNP L. We demonstrate that one such factor, the histone methyltransferase SETD2, specifically interacts with hnRNP L in vitro and in vivo. This interaction occurs through a previously uncharacterized domain in SETD2, the SETD2-hnRNP Interaction (SHI) domain, the deletion of which, leads to a reduced H3K36me3 deposition. Functionally, SETD2 regulates a subset of hnRNP L-targeted AS events. Our findings demonstrate that SETD2, by interacting with Pol II as well as hnRNP L, can mediate the crosstalk between the transcription and the splicing machinery. The methylation of Histone 3 at Lysine 36 (H3K36) has been implicated in the regulation of transcription and coupled processes such as mRNA splicing. Here the authors show that the histone methyltransferase SETD2 interacts with hnRNP L to mediate the crosstalk between the transcription and splicing machineries.
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8
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The role of hnRNPs in frontotemporal dementia and amyotrophic lateral sclerosis. Acta Neuropathol 2020; 140:599-623. [PMID: 32748079 PMCID: PMC7547044 DOI: 10.1007/s00401-020-02203-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/27/2020] [Accepted: 07/27/2020] [Indexed: 12/12/2022]
Abstract
Dysregulated RNA metabolism is emerging as a crucially important mechanism underpinning the pathogenesis of frontotemporal dementia (FTD) and the clinically, genetically and pathologically overlapping disorder of amyotrophic lateral sclerosis (ALS). Heterogeneous nuclear ribonucleoproteins (hnRNPs) comprise a family of RNA-binding proteins with diverse, multi-functional roles across all aspects of mRNA processing. The role of these proteins in neurodegeneration is far from understood. Here, we review some of the unifying mechanisms by which hnRNPs have been directly or indirectly linked with FTD/ALS pathogenesis, including their incorporation into pathological inclusions and their best-known roles in pre-mRNA splicing regulation. We also discuss the broader functionalities of hnRNPs including their roles in cryptic exon repression, stress granule assembly and in co-ordinating the DNA damage response, which are all emerging pathogenic themes in both diseases. We then present an integrated model that depicts how a broad-ranging network of pathogenic events can arise from declining levels of functional hnRNPs that are inadequately compensated for by autoregulatory means. Finally, we provide a comprehensive overview of the most functionally relevant cellular roles, in the context of FTD/ALS pathogenesis, for hnRNPs A1-U.
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9
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Multilevel Differential Control of Hormone Gene Expression Programs by hnRNP L and LL in Pituitary Cells. Mol Cell Biol 2018; 38:MCB.00651-17. [PMID: 29610151 PMCID: PMC5974433 DOI: 10.1128/mcb.00651-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/22/2018] [Indexed: 12/20/2022] Open
Abstract
The pituitary-derived somatolactotrophe GH3 cells secrete both growth hormone (GH) and prolactin (PRL). We have found that the hnRNP L and L-like (LL) paralogs differentially regulate alternative splicing of genes in these cells. Here, we show that hnRNP L is essential for PRL only, but LL is essential for both PRL and GH production. Transcriptome-wide RNA sequencing (RNA-Seq) analysis indicates that they differentially control groups of hormone or hormone-related genes involved in hormone production/regulation at total transcript and alternative exon levels. Interestingly, hnRNP L also specifically binds and prevents the aberrant usage of a nonconserved CA-rich intron piece of Prl pre-mRNA transcripts, and many others involved in endocrine functions, to prevent mostly cryptic last exons and mRNA truncation. Essential for the full hnRNP L effect on specific exons is a proline-rich region that emerged during evolution in vertebrate hnRNP L only but not LL. Together, our data demonstrate that the hnRNP L and its paralog, LL, differentially control hormone gene expression programs at multiple levels, and hnRNP L in particular is critical for protecting the transcriptome from aberrant usage of intronic sequences. The multilevel differential control by hnRNPs likely tailors the transcriptome to help refine and safeguard the different gene expression programs for different hormones.
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10
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HuR Displaces Polypyrimidine Tract Binding Protein To Facilitate La Binding to the 3' Untranslated Region and Enhances Hepatitis C Virus Replication. J Virol 2015; 89:11356-71. [PMID: 26339049 DOI: 10.1128/jvi.01714-15] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 08/25/2015] [Indexed: 12/12/2022] Open
Abstract
UNLABELLED HuR is a ubiquitous, RNA binding protein that influences the stability and translation of several cellular mRNAs. Here, we report a novel role for HuR, as a regulator of proteins assembling at the 3' untranslated region (UTR) of viral RNA in the context of hepatitis C virus (HCV) infection. HuR relocalizes from the nucleus to the cytoplasm upon HCV infection, interacts with the viral polymerase (NS5B), and gets redistributed into compartments of viral RNA synthesis. Depletion in HuR levels leads to a significant reduction in viral RNA synthesis. We further demonstrate that the interaction of HuR with the 3' UTR of the viral RNA affects the interaction of two host proteins, La and polypyrimidine tract binding protein (PTB), at this site. HuR interacts with La and facilitates La binding to the 3' UTR, enhancing La-mediated circularization of the HCV genome and thus viral replication. In addition, it competes with PTB for association with the 3' UTR, which might stimulate viral replication. Results suggest that HuR influences the formation of a cellular/viral ribonucleoprotein complex, which is important for efficient initiation of viral RNA replication. Our study unravels a novel strategy of regulation of HCV replication through an interplay of host and viral proteins, orchestrated by HuR. IMPORTANCE Hepatitis C virus (HCV) is highly dependent on various host factors for efficient replication of the viral RNA. Here, we have shown how a host factor (HuR) migrates from the nucleus to the cytoplasm and gets recruited in the protein complex assembling at the 3' untranslated region (UTR) of HCV RNA. At the 3' UTR, it facilitates circularization of the viral genome through interaction with another host factor, La, which is critical for replication. Also, it competes with the host protein PTB, which is a negative regulator of viral replication. Results demonstrate a unique strategy of regulation of HCV replication by a host protein through alteration of its subcellular localization and interacting partners. The study has advanced our knowledge of the molecular mechanism of HCV replication and unraveled the complex interplay between the host factors and viral RNA that could be targeted for therapeutic interventions.
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11
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Blatter M, Dunin-Horkawicz S, Grishina I, Maris C, Thore S, Maier T, Bindereif A, Bujnicki JM, Allain FHT. The Signature of the Five-Stranded vRRM Fold Defined by Functional, Structural and Computational Analysis of the hnRNP L Protein. J Mol Biol 2015; 427:3001-22. [PMID: 26051023 DOI: 10.1016/j.jmb.2015.05.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 05/01/2015] [Accepted: 05/04/2015] [Indexed: 12/23/2022]
Abstract
The RNA recognition motif (RRM) is the far most abundant RNA binding domain. In addition to the typical β1α1β2β3α2β4 fold, various sub-structural elements have been described and reportedly contribute to the high functional versatility of RRMs. The heterogeneous nuclear ribonucleoprotein L (hnRNP L) is a highly abundant protein of 64 kDa comprising four RRM domains. Involved in many aspects of RNA metabolism, hnRNP L specifically binds to RNAs containing CA repeats or CA-rich clusters. However, a comprehensive structural description of hnRNP L including its sub-structural elements is missing. Here, we present the structural characterization of the RRM domains of hnRNP L and demonstrate their function in repressing exon 4 of SLC2A2. By comparison of the sub-structural elements between the two highly similar paralog families of hnRNP L and PTB, we defined signatures underlying interacting C-terminal coils (ICCs), the RRM34 domain interaction and RRMs with a C-terminal fifth β-strand, a variation we denoted vRRMs. Furthermore, computational analysis revealed new putative ICC-containing RRM families and allowed us to propose an evolutionary scenario explaining the origins of the ICC and fifth β-strand sub-structural extensions. Our studies provide insights of domain requirements in alternative splicing mediated by hnRNP L and molecular descriptions for the sub-structural elements. In addition, the analysis presented may help to classify other abundant RRM extensions and to predict structure-function relationships.
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Affiliation(s)
- Markus Blatter
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | | | - Inna Grishina
- Institute of Biochemistry, Justus Liebig University of Giessen, 35392 Giessen, Germany
| | - Christophe Maris
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Stephane Thore
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Timm Maier
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland
| | - Albrecht Bindereif
- Institute of Biochemistry, Justus Liebig University of Giessen, 35392 Giessen, Germany
| | - Janusz M Bujnicki
- International Institute of Molecular and Cell Biology, 02-109 Warsaw, Poland; Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland
| | - Frédéric H-T Allain
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich, Switzerland.
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12
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Coelho MB, Attig J, Bellora N, König J, Hallegger M, Kayikci M, Eyras E, Ule J, Smith CWJ. Nuclear matrix protein Matrin3 regulates alternative splicing and forms overlapping regulatory networks with PTB. EMBO J 2015; 34:653-68. [PMID: 25599992 PMCID: PMC4365034 DOI: 10.15252/embj.201489852] [Citation(s) in RCA: 109] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Matrin3 is an RNA- and DNA-binding nuclear matrix protein found to be associated with neural and muscular degenerative diseases. A number of possible functions of Matrin3 have been suggested, but no widespread role in RNA metabolism has yet been clearly demonstrated. We identified Matrin3 by its interaction with the second RRM domain of the splicing regulator PTB. Using a combination of RNAi knockdown, transcriptome profiling and iCLIP, we find that Matrin3 is a regulator of hundreds of alternative splicing events, principally acting as a splicing repressor with only a small proportion of targeted events being co-regulated by PTB. In contrast to other splicing regulators, Matrin3 binds to an extended region within repressed exons and flanking introns with no sharply defined peaks. The identification of this clear molecular function of Matrin3 should help to clarify the molecular pathology of ALS and other diseases caused by mutations of Matrin3.
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Affiliation(s)
- Miguel B Coelho
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Jan Attig
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK MRC-Laboratory of Molecular Biology, Cambridge, UK
| | - Nicolás Bellora
- Computational Genomics, Universitat Pompeu Fabra, Barcelona, Spain Catalan Institute for Research and Advanced Studies (ICREA), Barcelona, Spain INIBIOMA CONICET-UNComahue, Bariloche, Argentina
| | - Julian König
- MRC-Laboratory of Molecular Biology, Cambridge, UK
| | - Martina Hallegger
- Department of Biochemistry, University of Cambridge, Cambridge, UK Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | | | - Eduardo Eyras
- Computational Genomics, Universitat Pompeu Fabra, Barcelona, Spain Catalan Institute for Research and Advanced Studies (ICREA), Barcelona, Spain
| | - Jernej Ule
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
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13
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Romano M, Buratti E, Romano G, Klima R, Del Bel Belluz L, Stuani C, Baralle F, Feiguin F. Evolutionarily conserved heterogeneous nuclear ribonucleoprotein (hnRNP) A/B proteins functionally interact with human and Drosophila TAR DNA-binding protein 43 (TDP-43). J Biol Chem 2014; 289:7121-7130. [PMID: 24492607 DOI: 10.1074/jbc.m114.548859] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human TDP-43 represents the main component of neuronal inclusions found in patients with neurodegenerative diseases, especially frontotemporal lobar degeneration and amyotrophic lateral sclerosis. In vitro and in vivo studies have shown that the TAR DNA-binding protein 43 (TDP-43) Drosophila ortholog (TBPH) can biochemically and functionally overlap the properties of the human factor. The recent direct implication of the human heterogeneous nuclear ribonucleoproteins (hnRNPs) A2B1 and A1, known TDP-43 partners, in the pathogenesis of multisystem proteinopathy and amyotrophic lateral sclerosis supports the hypothesis that the physical and functional interplay between TDP-43 and hnRNP A/B orthologs might play a crucial role in the pathogenesis of neurodegenerative diseases. To test this hypothesis and further validate the fly system as a useful model to study this type of diseases, we have now characterized human TDP-43 and Drosophila TBPH similarity in terms of protein-protein interaction pathways. In this work we show that TDP-43 and TBPH share the ability to associate in vitro with Hrp38/Hrb98DE/CG9983, the fruit fly ortholog of the human hnRNP A1/A2 factors. Interestingly, the protein regions of TDP-43 and Hrp38 responsible for reciprocal interactions are conserved through evolution. Functionally, experiments in HeLa cells demonstrate that TDP-43 is necessary for the inhibitory activity of Hrp38 on splicing. Finally, Drosophila in vivo studies show that Hrp38 deficiency produces locomotive defects and life span shortening in TDP-43 with and without animals. These results suggest that hnRNP protein levels can play a modulatory role on TDP-43 functions.
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Affiliation(s)
- Maurizio Romano
- Department of Life Sciences, University of Trieste, Via A. Valerio 28, 34127 Trieste, Italy.
| | - Emanuele Buratti
- International Centre for Genetic Engineering an Biotechnology, Padriciano 99, I-34149 Trieste, Italy
| | - Giulia Romano
- International Centre for Genetic Engineering an Biotechnology, Padriciano 99, I-34149 Trieste, Italy
| | - Raffaella Klima
- International Centre for Genetic Engineering an Biotechnology, Padriciano 99, I-34149 Trieste, Italy
| | - Lisa Del Bel Belluz
- Department of Life Sciences, University of Trieste, Via A. Valerio 28, 34127 Trieste, Italy
| | - Cristiana Stuani
- International Centre for Genetic Engineering an Biotechnology, Padriciano 99, I-34149 Trieste, Italy
| | - Francisco Baralle
- International Centre for Genetic Engineering an Biotechnology, Padriciano 99, I-34149 Trieste, Italy
| | - Fabian Feiguin
- International Centre for Genetic Engineering an Biotechnology, Padriciano 99, I-34149 Trieste, Italy
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14
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Remodelling of a polypyrimidine tract-binding protein complex during apoptosis activates cellular IRESs. Cell Death Differ 2013; 21:161-71. [PMID: 24141718 PMCID: PMC3857619 DOI: 10.1038/cdd.2013.135] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 01/08/2023] Open
Abstract
Post-transcriptional control of gene expression is mediated by the interaction of RNA-binding proteins with their cognate mRNAs that specifically regulate their stability, localization and translation. mRNA-binding proteins are multifunctional and it has been proposed therefore that a combinatorial RNA-binding protein code exists that allows specific protein sub-complexes to control cytoplasmic gene expression under a range of pathophysiological conditions. We show that polypyrimidine tract-binding protein (PTB) is central to one such complex that forms in apoptotic cells. Thus, during apoptosis initiated by TNF-related apoptosis inducing ligand there is a change in the repertoire of RNA-binding proteins with which PTB interacts. We show that altering the cellular levels of PTB and its binding partners, either singly or in combination, is sufficient to directly change the rates of apoptosis with increased expression of PTB, YBX1, PSF and NONO/p54nrb accelerating this process. Mechanistically, we show that these proteins post-transcriptionally regulate gene expression, and therefore apoptotic rates, by interacting with and stimulating the activity of RNA elements (internal ribosome entry segments) found in mRNAs that are translated during apoptosis. Taken together, our data show that PTB function is controlled by a set of co-recruited proteins and importantly provide further evidence that it is possible to dictate cell fate by modulating cytoplasmic gene expression pathways alone.
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15
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Rahman MA, Masuda A, Ohe K, Ito M, Hutchinson DO, Mayeda A, Engel AG, Ohno K. HnRNP L and hnRNP LL antagonistically modulate PTB-mediated splicing suppression of CHRNA1 pre-mRNA. Sci Rep 2013; 3:2931. [PMID: 24121633 PMCID: PMC3796306 DOI: 10.1038/srep02931] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 09/25/2013] [Indexed: 12/20/2022] Open
Abstract
CHRNA1 gene, encoding the muscle nicotinic acetylcholine receptor alpha subunit, harbors an inframe exon P3A. Inclusion of exon P3A disables assembly of the acetylcholine receptor subunits. A single nucleotide mutation in exon P3A identified in congenital myasthenic syndrome causes exclusive inclusion of exon P3A. The mutation gains a de novo binding affinity for a splicing enhancing RNA-binding protein, hnRNP LL, and displaces binding of a splicing suppressing RNA-binding protein, hnRNP L. The hnRNP L binds to another splicing repressor PTB through the proline-rich region and promotes PTB binding to the polypyrimidine tract upstream of exon P3A, whereas hnRNP LL lacking the proline-rich region cannot bind to PTB. Interaction of hnRNP L with PTB inhibits association of U2AF(65) and U1 snRNP with the upstream and downstream of P3A, respectively, which causes a defect in exon P3A definition. HnRNP L and hnRNP LL thus antagonistically modulate PTB-mediated splicing suppression of exon P3A.
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Affiliation(s)
- Mohammad Alinoor Rahman
- Division of Neurogenetics, Center for Neurological Diseases and Cancer, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
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16
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Lee KH, Kim SH, Lee HR, Kim W, Kim DY, Shin JC, Yoo SH, Kim KT. MicroRNA-185 oscillation controls circadian amplitude of mouse Cryptochrome 1 via translational regulation. Mol Biol Cell 2013; 24:2248-55. [PMID: 23699394 PMCID: PMC3708730 DOI: 10.1091/mbc.e12-12-0849] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The role of the 3′-untranslated region of the mouse Cryptochrome 1 (mCry1) gene is studied at the posttranscriptional level. The results suggest that miR-185 plays a role in the fine-tuned regulation of mCRY1 protein expression by controlling the rhythmicity of mCry1 mRNA translation. Mammalian circadian rhythm is observed not only at the suprachiasmatic nucleus, a master pacemaker, but also throughout the peripheral tissues. Investigation of the regulation of clock gene expression has mainly focused on transcriptional and posttranslational modifications, and little is known about the posttranscriptional regulation of these genes. In the present study, we investigate the role of microRNAs (miRNAs) in the posttranscriptional regulation of the 3′-untranslated region (UTR) of the mouse Cryptochrome 1 (mCry1) gene. Knockdown of Drosha, Dicer, or Argonaute2 increased mCry1-3′UTR reporter activity. The presence of the miRNA recognition element of mCry1 that is important for miR-185 binding decreased mCRY1 protein, but not mRNA, level. Cytoplasmic miR-185 levels were nearly antiphase to mCRY1 protein levels. Furthermore, miR-185 knockdown elevated the amplitude of mCRY1 protein oscillation. Our results suggest that miR-185 plays a role in the fine-tuned regulation of mCRY1 protein expression by controlling the rhythmicity of mCry1 mRNA translation.
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Affiliation(s)
- Kyung-Ha Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Gyeongbuk 790-784, Republic of Korea
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17
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Woo KC, Kim TD, Lee KH, Kim DY, Kim S, Lee HR, Kang HJ, Chung SJ, Senju S, Nishimura Y, Kim KT. Modulation of exosome-mediated mRNA turnover by interaction of GTP-binding protein 1 (GTPBP1) with its target mRNAs. FASEB J 2011; 25:2757-69. [PMID: 21515746 DOI: 10.1096/fj.10-178715] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Eukaryotic mRNA turnover is among most critical mechanisms that affect mRNA abundance and are regulated by mRNA-binding proteins and the cytoplasmic exosome. A functional protein, guanosine-triphosphate-binding protein 1 (GTPBP1), which associates with both the exosome and target mRNAs, was identified. The overexpression of GTPBP1 accelerated the target mRNA decay, whereas the reduction of the GTPBP1 expression with RNA interference stabilized the target mRNA. GTPBP1 has a putative guanosine-triphosphate (GTP)-binding domain, which is found in members of the G-protein family and Ski7p, a well-known core factor of the exosome-mediated mRNA turnover pathway in yeast. Analyses of protein interactions and mRNA decay demonstrated that GTPBP1 modulates mRNA degradation via GTP-binding-dependent target loading. Moreover, GTPBP1-knockout models displayed multiple mRNA decay defects, including elevated nocturnal levels of Aanat mRNA in pineal glands, and retarded degradation of TNF-α mRNA in lipopolysaccharide-treated splenocytes. The results of this study suggest that GTPBP1 is a regulator and adaptor of the exosome-mediated mRNA turnover pathway.
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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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18
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Kim DY, Woo KC, Lee KH, Kim TD, Kim KT. hnRNP Q and PTB modulate the circadian oscillation of mouse Rev-erb alpha via IRES-mediated translation. Nucleic Acids Res 2010; 38:7068-78. [PMID: 20576698 PMCID: PMC2978350 DOI: 10.1093/nar/gkq569] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The physiological and behavioral circadian rhythms of most creatures are controlled by a harmony of functional relationships between clock genes. In mammals, several core clock genes show rhythmic profiles of their mRNA and protein expression. Among them, Rev-erb α functions as a transcriptional repressor, affecting expression patterns of other clock genes. For the continuous and robust oscillation of the molecular clock system, the levels of Rev-erb α protein are expected to be tightly regulated with the correct timing. Here, we demonstrate that Rev-erb α has an internal ribosomal entry site (IRES) in its 5′ untranslated region. Furthermore, we demonstrate that heterogeneous nuclear ribonucleoprotein Q and polypyrimidine tract-binding protein (PTB) modulate the IRES-mediated translation of Rev-erb α. We suggest that the rhythmic binding affinity of hnRNP Q to the Rev-erb α IRES and the change in PTB cytosolic levels lead to maintenance of the oscillation profile of the Rev-erb α protein.
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Affiliation(s)
- Do-Yeon Kim
- Department of Life Science, Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, Gyeong-Buk, 790-784, Republic of Korea
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19
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Circadian amplitude of cryptochrome 1 is modulated by mRNA stability regulation via cytoplasmic hnRNP D oscillation. Mol Cell Biol 2010; 30:197-205. [PMID: 19858287 DOI: 10.1128/mcb.01154-09] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mammalian circadian rhythm is observed not only at the suprachiasmatic nucleus, a master pacemaker, but also throughout the peripheral tissues. Its conserved molecular basis has been thought to consist of intracellular transcriptional feedback loops of key clock genes. However, little is known about posttranscriptional regulation of these genes. In the present study, we investigated the role of the 3'-untranslated region (3'UTR) of the mouse cryptochrome 1 (mcry1) gene at the posttranscriptional level. Mature mcry1 mRNA has a 610-nucleotide 3'UTR and mediates its own degradation. The middle part of the 3'UTR contains a destabilizing cis-acting element. The deletion of this element led to a dramatic increase in mRNA stability, and heterogeneous nuclear ribonucleoprotein D (hnRNP D) was identified as an RNA binding protein responsible for this effect. Cytoplasmic hnRNP D levels displayed a pattern that was reciprocal to the mcry1 oscillation. Knockdown of hnRNP D stabilized mcry1 mRNA and resulted in enhancement of the oscillation amplitude and a slight delay of the phase. Our results suggest that hnRNP D plays a role as a fine regulator contributing to the mcry1 mRNA turnover rate and the modulation of circadian rhythm.
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20
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Inhibition of hepatitis C virus IRES-mediated translation by oligonucleotides. Virus Res 2009; 146:29-35. [PMID: 19720092 DOI: 10.1016/j.virusres.2009.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2009] [Revised: 08/11/2009] [Accepted: 08/21/2009] [Indexed: 02/08/2023]
Abstract
Two oligodeoxynucleotides (ODNs) were found to have a strong inhibition on the hepatitis C virus (HCV) internal ribosomal entry sites (IRES)-mediated translation but not the rabbit globin mRNA translation. Specific inhibition of those ODNs on HCV IRES-mediated translation was confirmed with heat treatment of ODNs in formic acid and dosage-dependent manners. Heat treatment of ODNs presented a decreasing inhibitory effect on HCV IRES-mediated translation. A dosage-dependent decrease of HCV IRES-mediated translation was observed with increasing amount of these ODNs in HeLa cell extracts. The minimal sequences of ODNs (A11) were identified as 5'-CGCGTTACG-3' with the strongest inhibition of the HCV IRES-mediated translation. In a search for cellular factors, two cellular factors (p68 and p70) were identified to interact with ODNs A1 and A11, but not A5 (CT-oligo). This data showed new kinds of cellular proteins involved in HCV IRES-mediated translation. Further study of ODNs and these cellular proteins will provide important information for understanding the mechanistic basis and molecular regulation of HCV IRES-mediated translation.
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21
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Niepmann M. Internal translation initiation of picornaviruses and hepatitis C virus. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:529-41. [PMID: 19439208 DOI: 10.1016/j.bbagrm.2009.05.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 04/29/2009] [Accepted: 05/02/2009] [Indexed: 01/02/2023]
Abstract
Picornaviruses and other positive-strand RNA viruses like hepatitis C virus (HCV) enter the cell with a single RNA genome that directly serves as the template for translation. Accordingly, the viral RNA genome needs to recruit the cellular translation machinery for viral protein synthesis. By the use of internal ribosome entry site (IRES) elements in their genomic RNAs, these viruses bypass translation competition with the bulk of capped cellular mRNAs and, moreover, establish the option to largely shut-down cellular protein synthesis. In this review, I discuss the structure and function of viral IRES elements, focusing on the recruitment of the cellular translation machinery by the IRES and on factors that may contribute to viral tissue tropism on the level of translation.
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Affiliation(s)
- Michael Niepmann
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, Friedrichstrasse 24, 35392 Giessen, Germany.
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22
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The hnRNA-binding proteins hnRNP L and PTB are required for efficient translation of the Cat-1 arginine/lysine transporter mRNA during amino acid starvation. Mol Cell Biol 2009; 29:2899-912. [PMID: 19273590 DOI: 10.1128/mcb.01774-08] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The response to amino acid starvation involves the global decrease of protein synthesis and an increase in the translation of some mRNAs that contain an internal ribosome entry site (IRES). It was previously shown that translation of the mRNA for the arginine/lysine amino acid transporter Cat-1 increases during amino acid starvation via a mechanism that utilizes an IRES in the 5' untranslated region of the Cat-1 mRNA. It is shown here that polypyrimidine tract binding protein (PTB) and an hnRNA binding protein, heterogeneous nuclear ribonucleoprotein L (hnRNP L), promote the efficient translation of Cat-1 mRNA during amino acid starvation. Association of both proteins with Cat-1 mRNA increased during starvation with kinetics that paralleled that of IRES activation, although the levels and subcellular distribution of the proteins were unchanged. The sequence CUUUCU within the Cat-1 IRES was important for PTB binding and for the induction of translation during amino acid starvation. Binding of hnRNP L to the IRES or the Cat-1 mRNA in vivo was independent of PTB binding but was not sufficient to increase IRES activity or Cat-1 mRNA translation during amino acid starvation. In contrast, binding of PTB to the Cat-1 mRNA in vivo required hnRNP L. A wider role of hnRNP L in mRNA translation was suggested by the decrease of global protein synthesis in cells with reduced hnRNP L levels. It is proposed that PTB and hnRNP L are positive regulators of Cat-1 mRNA translation via the IRES under stress conditions that cause a global decrease of protein synthesis.
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23
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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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24
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Hwang B, Lim JH, Hahm B, Jang SK, Lee SW. hnRNP L is required for the translation mediated by HCV IRES. Biochem Biophys Res Commun 2008; 378:584-8. [PMID: 19061868 DOI: 10.1016/j.bbrc.2008.11.091] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2008] [Accepted: 11/18/2008] [Indexed: 01/04/2023]
Abstract
Translation of hepatitis C virus (HCV) RNA is initiated by internal loading of the ribosome into the HCV internal ribosome entry site (IRES). Previously, heterogeneous ribonucleoprotein L (hnRNP L) was shown to bind specifically to the 3' border region of the HCV IRES and enhance HCV mRNA translation. Here, we provide evidence for the functional requirement of hnRNP L for the HCV IRES-mediated translation initiation using specific RNA aptamers. In vitro selection techniques were employed to isolate RNA aptamers against hnRNP L, which were shown to contain consensus sequences with repetitive ACAC/U. The hnRNP L-specific RNA aptamers efficiently inhibited the in vitro translation reactions mediated by the HCV IRES in rabbit reticulocyte lysates. RNA ligands with only (ACAU)5 or (AC)10 nucleotide sequences could also specifically bind to hnRNP L, and specifically and effectively impeded in vitro translation reactions controlled by the HCV IRES. Importantly, the hnRNP L-specific RNA aptamers inhibited the HCV IRES function in cells in a dose-dependent manner, and the aptamer-mediated inhibition of the HCV IRES was considerably relieved by the addition of hnRNP L-expressing vector. These results strongly demonstrate the functional requirement of cellular hnRNP L for the HCV IRES activity.
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Affiliation(s)
- Byounghoon Hwang
- Department of Molecular Biology, Institute of Nanosensor and Biotechnology, Dankook University, 126, Jukjeon-dong, Suji-gu, Yongin 448-701, Republic of Korea
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25
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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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Hung LH, Heiner M, Hui J, Schreiner S, Benes V, Bindereif A. Diverse roles of hnRNP L in mammalian mRNA processing: a combined microarray and RNAi analysis. RNA (NEW YORK, N.Y.) 2008; 14:284-96. [PMID: 18073345 PMCID: PMC2212255 DOI: 10.1261/rna.725208] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Alternative mRNA splicing patterns are determined by the combinatorial control of regulator proteins and their target RNA sequences. We have recently characterized human hnRNP L as a global regulator of alternative splicing, binding to diverse C/A-rich elements. To systematically identify hnRNP L target genes on a genome-wide level, we have combined splice-sensitive microarray analysis and an RNAi-knockdown approach. As a result, we describe 11 target genes of hnRNP L that were validated by RT-PCR and that represent several new modes of hnRNP L-dependent splicing regulation, involving both activator and repressor functions: first, intron retention; second, inclusion or skipping of cassette-type exons; third, suppression of multiple exons; and fourth, alternative poly(A) site selection. In sum, this approach revealed a surprising diversity of splicing-regulatory processes as well as poly(A) site selection in which hnRNP L is involved.
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Affiliation(s)
- Lee-Hsueh Hung
- Institute of Biochemistry, Justus-Liebig-University of Giessen, D-35392 Giessen, Germany
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27
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Laughlin J, Oghlidos S, Porter JF, Matus-Nicodemos R, Sinquett FL, Marcelli V, Covey LR. Functional analysis of a tripartite stability element within the CD40 ligand 3' untranslated region. Immunology 2008; 124:368-79. [PMID: 18194270 DOI: 10.1111/j.1365-2567.2007.02783.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
We previously identified a cis-acting element within the 3' untranslated region of CD40 ligand messenger RNA (mRNA) that is composed of three complex binding sites and acts to increase mRNA stability in both in vitro and in vivo systems. We now demonstrate the functional consequences of the three binding sites with respect to increasing both luciferase activity and mRNA stability in a heterologous transcript expressed in a T-cell line. The internal region B was shown to be a bona fide stability element because its presence increased luciferase activity fourfold over the unmodified transcript and its removal from the XbaI-HaeIII region resulted in rapid degradation of the transcript. Region A contained both a binding site for a polypyrimidine-tract-binding protein (PTB)-mediated complex (Complex I) and an upstream, adjacent sequence that was a negative regulator of mRNA stability. Region C bound Complex II, which contained both PTB and heterogeneous nuclear ribonucleoproteinL (hnRNPL), and was less effective as a stability element on its own compared to region B. Our findings demonstrate differential levels of activity for the three binding sites relative to the turnover of CD40 ligand mRNA, suggesting that the lack of binding of Complex I/II during the early stages of T-cell activation contributes to the rapid degradation of the CD40 ligand mRNA transcript.
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Affiliation(s)
- Jennifer Laughlin
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ, USA
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28
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Han S, Choi M. Human ribosomal protein L18a interacts with hnRNP E1. Anim Cells Syst (Seoul) 2008. [DOI: 10.1080/19768354.2008.9647167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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29
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Heterogeneous nuclear ribonucleoprotein D/AUF1 interacts with heterogeneous nuclear ribonucleoprotein L. J Biosci 2007; 32:1263-72. [DOI: 10.1007/s12038-007-0135-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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30
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Martinez-Contreras R, Cloutier P, Shkreta L, Fisette JF, Revil T, Chabot B. hnRNP proteins and splicing control. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 623:123-47. [PMID: 18380344 DOI: 10.1007/978-0-387-77374-2_8] [Citation(s) in RCA: 273] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Proteins of the heterogeneous nuclear ribonucleoparticles (hnRNP) family form a structurally diverse group of RNA binding proteins implicated in various functions in metazoans. Here we discuss recent advances supporting a role for these proteins in precursor-messenger RNA (pre-mRNA) splicing. Heterogeneous nuclear RNP proteins can repress splicing by directly antagonizing the recognition of splice sites, or can interfere with the binding of proteins bound to enhancers. Recently, hnRNP proteins have been shown to hinder communication between factors bound to different splice sites. Conversely, several reports have described a positive role for some hnRNP proteins in pre-mRNA splicing. Moreover, cooperative interactions between bound hnRNP proteins may encourage splicing between specific pairs of splice sites while simultaneously hampering other combinations. Thus, hnRNP proteins utilize a variety of strategies to control splice site selection in a manner that is important for both alternative and constitutive pre-mRNA splicing.
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31
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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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32
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Rideau AP, Gooding C, Simpson PJ, Monie TP, Lorenz M, Hüttelmaier S, Singer RH, Matthews S, Curry S, Smith CWJ. A peptide motif in Raver1 mediates splicing repression by interaction with the PTB RRM2 domain. Nat Struct Mol Biol 2006; 13:839-48. [PMID: 16936729 DOI: 10.1038/nsmb1137] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 07/27/2006] [Indexed: 11/08/2022]
Abstract
Polypyrimidine tract-binding protein (PTB) is a regulatory splicing repressor. Raver1 acts as a PTB corepressor for splicing of alpha-tropomyosin (Tpm1) exon 3. Here we define a minimal region of Raver1 that acts as a repressor domain when recruited to RNA. A conserved [S/G][I/L]LGxxP motif is essential for splicing repressor activity and sufficient for interaction with PTB. An adjacent proline-rich region is also essential for repressor activity but not for PTB interaction. NMR analysis shows that LLGxxP peptides interact with a hydrophobic groove on the dorsal surface of the RRM2 domain of PTB, which constitutes part of the minimal repressor region of PTB. The requirement for the PTB-Raver1 interaction that we have characterized may serve to bring the additional repressor regions of both proteins into a configuration that allows them to synergistically effect exon skipping.
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Affiliation(s)
- Alexis P Rideau
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, CB2 1GA, UK
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33
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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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34
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Song Y, Tzima E, Ochs K, Bassili G, Trusheim H, Linder M, Preissner KT, Niepmann M. Evidence for an RNA chaperone function of polypyrimidine tract-binding protein in picornavirus translation. RNA (NEW YORK, N.Y.) 2005; 11:1809-24. [PMID: 16314455 PMCID: PMC1370870 DOI: 10.1261/rna.7430405] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Accepted: 09/20/2005] [Indexed: 05/05/2023]
Abstract
The cellular polypyrimidine tract-binding protein (PTB) is recruited by the genomic RNAs of picornaviruses to stimulate translation initiation at their internal ribosome entry site (IRES) elements. We investigated the contribution of the individual RNA recognition motif (RRM) domains of PTB to its interaction with the IRES of foot-and-mouth disease virus (FMDV). Using a native gel system, we found that PTB is a monomer, confirming recent reports that challenged the previous view that PTB is a dimer. Mapping the spatial orientation of PTB relative to the bound IRES RNA, we found that the two C-terminal RRM domains III and IV of PTB bind in an oriented way to the IRES. Domain III contacts the IRES stem-loop 2, while domain IV contacts the separate IRES 3' region. PTB domain I appears not to be involved directly in RNA binding, but domain II stabilizes the RNA binding conferred by domains III and IV. A PTB protein containing only these two C-terminal PTB domains is sufficient to enhance the entry of initiation factor eIF4G to the IRES and stimulate IRES activity, and the long-lived PTB-IRES interaction stabilized by domain II is not a prerequisite for this function. Thus, PTB most likely acts as an RNA chaperone to stabilize IRES structure and, in that way, augment IRES activity.
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Affiliation(s)
- Yutong Song
- Institute of Biochemistry, Faculty of Medicine, Justus-Liebig-University, 35392 Giessen, Germany
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35
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Investigation of interactions of polypyrimidine tract-binding protein with artificial internal ribosome entry segments. Biochem Soc Trans 2005; 33:1483-6. [PMID: 16246151 DOI: 10.1042/bst0331483] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Most eukaryotic translation initiation is thought to be dependent on the 5'-cap structure of the mRNA. It is becoming apparent, however, that the mRNAs of many genes contain IRESs (internal ribosome entry segments) within the 5'-UTR (5'-untranslated region) that allow ribosomes to initiate translation independently of the 5'-cap. IRESs can enable the expression of these genes under conditions (such as viral infection, cellular stress and apoptosis) when cap-dependent translation initiation is compromised, and also provide a target for regulation of gene expression. Recent results from our laboratory and others suggest that 10% of mRNAs (approximately 4000 genes) use this mechanism to initiate translation. One of the central goals of those working in the field of translation is to identify the sequence motif(s) and proteins that are required for internal ribosome entry. We have identified recently a unique PTB (polypyrimidine tract-binding protein) motif (CCU)n that is present in a large subset of cellular IRESs, and the results suggest that PTB itself is involved either directly or indirectly in ribosome recruitment. Here, we describe further investigations of PTB with artificial sequences that harbour this motif.
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36
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Buratti E, Brindisi A, Giombi M, Tisminetzky S, Ayala YM, Baralle FE. TDP-43 Binds Heterogeneous Nuclear Ribonucleoprotein A/B through Its C-terminal Tail. J Biol Chem 2005; 280:37572-84. [PMID: 16157593 DOI: 10.1074/jbc.m505557200] [Citation(s) in RCA: 367] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
TDP-43 is a highly conserved nuclear factor of yet unknown function that binds to ug-repeated sequences and is responsible for cystic fibrosis transmembrane conductance regulator exon 9 splicing inhibition. We have analyzed TDP-43 interactions with other splicing factors and identified the critical regions for the protein/protein recognition events that determine this biological function. We show here that the C-terminal region of TDP-43 is capable of binding directly to several proteins of the heterogeneous nuclear ribonucleoprotein (hnRNP) family with well known splicing inhibitory activity, in particular, hnRNP A2/B1 and hnRNP A1. Mutational analysis showed that TDP-43 proteins lacking the C-terminal region could not inhibit splicing probably because they were unable to form the hnRNP-rich complex involved in splicing inhibition. Finally, through splicing complex analysis, we show that splicing inhibition mediated by TDP-43 occurs at the earliest stages of spliceosomal assembly.
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Affiliation(s)
- Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
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37
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Spriggs KA, Bushell M, Mitchell SA, Willis AE. Internal ribosome entry segment-mediated translation during apoptosis: the role of IRES-trans-acting factors. Cell Death Differ 2005; 12:585-91. [PMID: 15900315 DOI: 10.1038/sj.cdd.4401642] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
During apoptosis, there is a reduction in translation initiation caused by caspase cleavage of several of the factors required for the cap-dependent scanning mechanism. Under these circumstances, many proteins that are required for apoptosis are instead translated by the alternative method of internal ribosome entry. This mechanism requires the formation of a complex RNA structural element and in the presence of internal ribosome entry segment (IRES)-trans-acting factors (ITAFs), the ribosome is recruited to the RNA. The interactions of several ITAFs with IRESs have been investigated in detail, and several mechanisms of action have been noted, including acting as chaperones, stabilising and remodelling the RNA structure. Structural remodelling by PTB in particular will be discussed, and how this protein is able to facilitate recruitment of the ribosome to several IRESs by causing previously occluded sites to become more accessible.
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Affiliation(s)
- K A Spriggs
- School of Pharmacy, University of Nottingham, University Park, Nottingham, UK
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38
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McKee AE, Minet E, Stern C, Riahi S, Stiles CD, Silver PA. A genome-wide in situ hybridization map of RNA-binding proteins reveals anatomically restricted expression in the developing mouse brain. BMC DEVELOPMENTAL BIOLOGY 2005; 5:14. [PMID: 16033648 PMCID: PMC1199591 DOI: 10.1186/1471-213x-5-14] [Citation(s) in RCA: 129] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2005] [Accepted: 07/20/2005] [Indexed: 11/10/2022]
Abstract
Background In eukaryotic cells, RNA-binding proteins (RBPs) contribute to gene expression by regulating the form, abundance, and stability of both coding and non-coding RNA. In the vertebrate brain, RBPs account for many distinctive features of RNA processing such as activity-dependent transcript localization and localized protein synthesis. Several RBPs with activities that are important for the proper function of adult brain have been identified, but how many RBPs exist and where these genes are expressed in the developing brain is uncharacterized. Results Here we describe a comprehensive catalogue of the unique RBPs encoded in the mouse genome and provide an online database of RBP expression in developing brain. We identified 380 putative RBPs in the mouse genome. Using in situ hybridization, we visualized the expression of 323 of these RBP genes in the brains of developing mice at embryonic day 13.5, when critical fate choice decisions are made and at P0, when major structural components of the adult brain are apparent. We demonstrate i) that 16 of the 323 RBPs examined show neural-specific expression at the stages we examined, and ii) that a far larger subset (221) shows regionally restricted expression in the brain. Of the regionally restricted RBPs, we describe one group that is preferentially expressed in the E13.5 ventricular areas and a second group that shows spatially restricted expression in post-mitotic regions of the embryonic brain. Additionally, we find a subset of RBPs that share the same complex pattern of expression, in proliferating regions of the embryonic and postnatal NS and peripheral tissues. Conclusion Our data show that, in contrast to their proposed ubiquitous involvement in gene regulation, most RBPs are not uniformly expressed. Here we demonstrate the region-specific expression of RBPs in proliferating vs. post-mitotic brain regions as well as cell-type-specific RBP expression. We identify uncharacterized RBPs that exhibit neural-specific expression as well as novel RBPs that show expression in non-neural tissues. The data presented here and in an online database provide a visual filter for the functional analysis of individual RBPs.
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Affiliation(s)
- Adrienne E McKee
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115 USA
- Department of Cancer Biology, The Dana-Farber Cancer Institute, Boston, MA 02115 USA
| | - Emmanuel Minet
- Department of Cancer Biology, The Dana-Farber Cancer Institute, Boston, MA 02115 USA
- URBC-FUNDP, 61 rue de Bruxelles, 5000 Namur, Belgium
| | - Charlene Stern
- Department of Cancer Biology, The Dana-Farber Cancer Institute, Boston, MA 02115 USA
| | - Shervin Riahi
- Department of Cancer Biology, The Dana-Farber Cancer Institute, Boston, MA 02115 USA
| | - Charles D Stiles
- Department of Cancer Biology, The Dana-Farber Cancer Institute, Boston, MA 02115 USA
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Pamela A Silver
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115 USA
- Department of Cancer Biology, The Dana-Farber Cancer Institute, Boston, MA 02115 USA
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39
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Mitchell SA, Spriggs KA, Bushell M, Evans JR, Stoneley M, Le Quesne JPC, Spriggs RV, Willis AE. Identification of a motif that mediates polypyrimidine tract-binding protein-dependent internal ribosome entry. Genes Dev 2005; 19:1556-71. [PMID: 15998809 PMCID: PMC1172062 DOI: 10.1101/gad.339105] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Accepted: 05/19/2005] [Indexed: 02/05/2023]
Abstract
We have identified a novel motif which consists of the sequence (CCU)(n) as part of a polypyrimidine-rich tract and permits internal ribosome entry. A number of constructs containing variations of this motif were generated and these were found to function as artificial internal ribosome entry segments (AIRESs) in vivo and in vitro in the presence of polypyrimidine tract-binding protein (PTB). The data show that for these sequences to function as IRESs the RNA must be present as a double-stranded stem and, in agreement with this, rather surprisingly, we show that PTB binds strongly to double-stranded RNA. All the cellular 5' untranslated regions (UTRs) tested that harbor this sequence were shown to contain internal ribosome entry segments that are dependent upon PTB for function in vivo and in vitro. This therefore raises the possibility that PTB or its interacting protein partners could provide a bridge between the IRES-RNA and the ribosome. Given the number of putative cellular IRESs that could be dependent on PTB for function, these data strongly suggest that PTB-1 is a universal IRES-trans-acting factor.
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Affiliation(s)
- Sally A Mitchell
- School of Pharmacy, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
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Kim TD, Kim JS, Kim JH, Myung J, Chae HD, Woo KC, Jang SK, Koh DS, Kim KT. Rhythmic serotonin N-acetyltransferase mRNA degradation is essential for the maintenance of its circadian oscillation. Mol Cell Biol 2005; 25:3232-46. [PMID: 15798208 PMCID: PMC1069600 DOI: 10.1128/mcb.25.8.3232-3246.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase [AANAT]) is the key enzyme in melatonin synthesis regulated by circadian rhythm. To date, our understanding of the oscillatory mechanism of melatonin has been limited to autoregulatory transcriptional and posttranslational regulations of AANAT mRNA. In this study, we identify three proteins from pineal glands that associate with cis-acting elements within species-specific AANAT 3' untranslated regions to mediate mRNA degradation. These proteins include heterogeneous nuclear ribonucleoprotein R (hnRNP R), hnRNP Q, and hnRNP L. Their RNA-destabilizing function was determined by RNA interference and overexpression approaches. Expression patterns of these factors in pineal glands display robust circadian rhythm. The enhanced levels detected after midnight correlate with an abrupt decline in AANAT mRNA level. A mathematical model for the AANAT mRNA profile and its experimental evidence with rat pinealocytes indicates that rhythmic AANAT mRNA degradation mediated by hnRNP R, hnRNP Q, and hnRNP L is a key process in the regulation of its circadian oscillation.
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Affiliation(s)
- Tae-Don Kim
- National Research Laboratory, Department of Life Science, Pohang University of Science and Technology, San 31 Hyoja-Dong, Pohang, Kyung-Buk 790-784, Republic of Korea
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41
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Kim JH, Paek KY, Ha SH, Cho S, Choi K, Kim CS, Ryu SH, Jang SK. A cellular RNA-binding protein enhances internal ribosomal entry site-dependent translation through an interaction downstream of the hepatitis C virus polyprotein initiation codon. Mol Cell Biol 2004; 24:7878-90. [PMID: 15340051 PMCID: PMC515056 DOI: 10.1128/mcb.24.18.7878-7890.2004] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Revised: 05/17/2004] [Accepted: 06/17/2004] [Indexed: 02/07/2023] Open
Abstract
Translational initiation of hepatitis C virus (HCV) mRNA occurs by internal entry of ribosomes into an internal ribosomal entry site (IRES) at the 5' nontranslated region. A region encoding the N-terminal part of the HCV polyprotein has been shown to augment the translation of HCV mRNA. Here we show that a cellular protein, NS1-associated protein 1 (NSAP1), augments HCV mRNA translation through a specific interaction with an adenosine-rich protein-coding region within the HCV mRNA. The overexpression of NSAP1 specifically enhanced HCV IRES-dependent translation, and knockdown of NSAP1 by use of a small interfering RNA specifically inhibited the translation of HCV mRNA. An HCV replicon RNA capable of mimicking the HCV proliferation process in host cells was further used to confirm that NSAP1 enhances the translation of HCV mRNA. These results suggest the existence of a novel mechanism of translational enhancement that acts through the interaction of an RNA-binding protein with a protein coding sequence.
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Affiliation(s)
- Jong Heon Kim
- NRL, PBC, Division of Molecular and Life Sciences, Pohang University of Science and Technology, Hyoja-Dong San 31, Pohang, Kyungbuk 790-784, South Korea
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42
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Taguchi F, Kusaba H, Asai A, Iwamoto Y, Yano K, Nakano H, Mizukami T, Saijo N, Kato H, Nishio K. hnRNP L enhances sensitivity of the cells to KW-2189. Int J Cancer 2004; 108:679-85. [PMID: 14696094 DOI: 10.1002/ijc.11616] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) are involved in several RNA-related biological processes. We demonstrated hnRNP L as a candidate protein of DARP (duocarmycin-DNA adduct recognizing protein) by gel shift assay and amino acid sequencing. Stable transfectants of hnRNP L showed high sensitivity of the cells to the growth inhibitory effect of KW-2189, a duocarmycin derivative in vitro. Immunostaining of hnRNP L demonstrated differential intracellular localization of hnRNP L among human lung cancer cell lines. A transfection study using a series of deletion mutants of hnRNP L fused to indicated that the N-terminal portions of RRM(RNA recognition motif)1, RRM3 and RRM2 are involved in localization of hnRNP L. We identified sequences in these portions that have high homology with the sequences of known NLS (nuclear localization signal) and NES (nuclear export signal). hnRNP L is a factor that determines the sensitivities of cancer cells to the minor groove binder, and overexpression and differential intracellular localization of hnRNP L are involved in its function in lung cancer.
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Affiliation(s)
- Fumiko Taguchi
- Pharmacology Division, National Cancer Center Research Institute, Tokyo, Japan
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Hamilton BJ, Genin A, Cron RQ, Rigby WFC. Delineation of a novel pathway that regulates CD154 (CD40 ligand) expression. Mol Cell Biol 2003; 23:510-25. [PMID: 12509450 PMCID: PMC151525 DOI: 10.1128/mcb.23.2.510-525.2003] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2002] [Revised: 07/18/2002] [Accepted: 10/07/2002] [Indexed: 02/05/2023] Open
Abstract
The expression of CD154 (CD40 ligand) by activated T lymphocytes plays a central role in humoral and cellular immunity. The fundamental importance of this protein in mounting an immune response has made it an attractive target for immunomodulation. Several studies have demonstrated that CD154 expression is regulated at the level of mRNA turnover in a manner distinct from other cytokine genes. We have purified, sequenced, and characterized the two major proteins that bind the CD154 3' untranslated region (3'UTR) as members of the polypyrimidine tract binding protein (PTB) family. One of these proteins is a previously unreported alternatively spliced PTB isoform, which we call PTB-T. These proteins interact with a polypyrimidine-rich region within the CD154 3'UTR that lacks any known cis-acting instability elements. The polypyrimidine-rich region of the CD154 3'UTR was both necessary and sufficient to mediate changes in reporter gene expression and mRNA accumulation, indicating the presence of a novel cis-acting instability element. The presence of a cis-acting instability element in the polypyrimidine-rich region was confirmed using a tetracycline-responsive reporter gene approach. The function of this cis-acting element appears to be dependent on the relative cytoplasmic levels of PTB and PTB-T. Cotransfection of vectors encoding PTB-T consistently decreased the CD154 3'UTR-dependent luciferase expression. In contrast, transfection of plasmids encoding PTB tended to increase CD154 3'UTR-dependent luciferase expression. Thus, the CD154 3'UTR contains a novel cis-acting element whose function is determined by the binding of PTB and PTB-T. These data identify a specific pathway that regulates CD154 expression that can potentially be selectively targeted for the treatment of autoimmune disease and allograft rejection.
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Affiliation(s)
- B JoNell Hamilton
- Departments of Medicine. Microbiology and Immunology, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA
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Rosenberger U, Lehmann I, Weise C, Franke P, Hucho F, Buchner K. Identification of PSF as a protein kinase Calpha-binding protein in the cell nucleus. J Cell Biochem 2002; 86:394-402. [PMID: 12112008 DOI: 10.1002/jcb.10233] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Protein kinase C (PKC) isoforms are present in the cell nucleus in diverse cell lines and tissues. Since little is known about proteins interacting with PKC inside the cell nucleus, we used Neuro-2a neuroblastoma cells, in which PKCalpha is present in the nucleus, to screen for nuclear binding partners for PKC. Applying overlay assays, we detected several nuclear proteins which bind to PKCalpha. Specificity of binding was shown by its dependence on PKC activation by phorbol ester, calcium, and phosphatidylserine. The PKC-binding proteins were partially purified and analyzed by microsequencing and mass spectrometry. Four proteins could be identified: PTB-associated splicing factor (PSF), p68 RNA helicase, and the heterogeneous nuclear ribonucleoprotein (hnRNP) proteins A3 and L. In the case of PSF, binding to PKC could also be demonstrated in a GST-pull-down assay using GST-PKCalpha, expressed in insect cells. Phosphorylation experiments revealed that PSF is a weak in vitro substrate for PKCalpha.
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Affiliation(s)
- Uwe Rosenberger
- Freie Universität Berlin, Institut für Chemie-Biochemie, AG Neurochemie, Thielallee 63, 14195 Berlin, Germany
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Kim YK, Jang SK. Continuous heat shock enhances translational initiation directed by internal ribosomal entry site. Biochem Biophys Res Commun 2002; 297:224-31. [PMID: 12237106 DOI: 10.1016/s0006-291x(02)02154-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Many cellular mRNAs contain internal ribosomal entry sites (IRES) that become functional under conditions of cellular stress, when the rate of protein synthesis for most cellular mRNA is reduced. Internal ribosomal entry increases in response to hypoxia, cell differentiation, apoptosis, gamma irradiation, and heat shock. Heat shock is the principal cellular stress in which general cap-dependent translation is inhibited. On the other hand, heat shock induces the preferential translation of a small class of mRNA, called heat shock protein (HSP) mRNAs, which probably occurs because little or no eIF4F activity is required for their translation. In this study, we found that continuous heat stress enhances expression of the heat shock protein BiP at the level of translation. Interestingly, heat stress also enhanced the viral IRES-dependent translation of encephalomyocarditis virus and hepatitis C virus but not poliovirus. Although several BiP inducers increased BiP protein expression, BiP IRES-dependent translation was enhanced only during heat shock, suggesting that heat shock is a specific inducer for BiP IRES-dependent translation. Taken together, these results indicate that the mechanism of IRES-dependent translation can be used during heat shock and suggest that this translational mechanism may be critical to the survival and proliferation of cells under stress.
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Affiliation(s)
- Yoon Ki Kim
- NRL, Division of Molecular and Life Sciences, Department of Life Science, Pohang University of Science and Technology, San31, Hyoja-Dong, Pohang, Kyungbuk 790-784, Republic of Korea
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Söderberg M, Raffalli-Mathieu F, Lang MA. Inflammation modulates the interaction of heterogeneous nuclear ribonucleoprotein (hnRNP) I/polypyrimidine tract binding protein and hnRNP L with the 3'untranslated region of the murine inducible nitric-oxide synthase mRNA. Mol Pharmacol 2002; 62:423-31. [PMID: 12130696 DOI: 10.1124/mol.62.2.423] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Interaction of two members of the heterogeneous nuclear ribonucleoprotein (hnRNP) family with the 3'untranslated region (UTR) of the murine inducible nitric-oxide synthase (iNOS) mRNA is demonstrated in this study. An iNOS RNA-protein complex is formed using protein extracts from untreated and septic shock treated mouse liver. UV cross-linking reveals that the complex consists of at least two proteins, with apparent molecular masses of 60 and 70 kDa, respectively. The 60-kDa protein binding site lies within a 112-nt pyrimidine-rich sequence, approximately 160 nt from the coding sequence, and the RNA-protein complex can be precipitated by a monoclonal antibody directed against hnRNP I [also named polypyrimidine tract binding protein (PTB)]. The 70-kDa protein binds a 43-nt sequence near the 3'end of the 3'UTR and is immunoprecipitated by a monoclonal antibody against hnRNP L. A computer-simulated conformation of the 3'UTR suggests that both binding sites reside in regions easily accessible for a protein. Supershifts of the native RNA-protein complex could only be achieved with anti-hnRNP L, suggesting that within this multiprotein RNA complex, only hnRNP L is exposed to the antibodies, whereas the hnRNP I/PTB is mainly responsible for its interaction with the mRNA. Up-regulation of iNOS by septic shock reduces the RNA-protein complex formation, thus showing that hnRNP I/PTB and hnRNP L binding to the iNOS mRNA is modulated by inflammation. This suggests a novel function for the two previously described proteins as regulators of the iNOS gene.
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Affiliation(s)
- Malin Söderberg
- Division of Biochemistry, Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden.
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Expert-Bezançon A, Le Caer JP, Marie J. Heterogeneous nuclear ribonucleoprotein (hnRNP) K is a component of an intronic splicing enhancer complex that activates the splicing of the alternative exon 6A from chicken beta-tropomyosin pre-mRNA. J Biol Chem 2002; 277:16614-23. [PMID: 11867641 DOI: 10.1074/jbc.m201083200] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Splicing of the chicken beta-tropomyosin exon 6A is stimulated, both in vivo and in vitro, by an intronic pyrimidine-rich element (S4) located 37 nucleotides downstream of exon 6A. Several pyrimidine-rich sequences are able to substitute for the natural S4 enhancer with various stimulatory effects. We show that the different enhancer sequences recruit U1 small nuclear ribonucleoprotein (SnRNP) to the exon 6A 5' splice site, with an efficiency that correlates with the splicing activation. By using RNA affinity and two-dimensional gel electrophoresis, we characterized several proteins that bind to the different enhancer sequences. Heterogeneous nuclear ribonucleoprotein (hnRNP) K and hnRNP I (polypyrimidine track-binding protein, PTB) exhibit a higher level of interaction with the strong enhancer sequences (S4) than with the weakest enhancers. Functional analysis shows that hnRNP K is a component of the enhancer complex that promotes exon 6A splicing through the wild-type S4 sequence. The addition of recombinant hnRNP K to nuclear extracts preincubated with poly(rC) RNA competitor completely restores splicing efficiency to the original level. hnRNP I (PTB) was also found associated with the strong enhancer sequences. Its function in the splicing of exon 6A is discussed.
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Back SH, Kim YK, Kim WJ, Cho S, Oh HR, Kim JE, Jang SK. Translation of polioviral mRNA is inhibited by cleavage of polypyrimidine tract-binding proteins executed by polioviral 3C(pro). J Virol 2002; 76:2529-42. [PMID: 11836431 PMCID: PMC135932 DOI: 10.1128/jvi.76.5.2529-2542.2002] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2001] [Accepted: 12/04/2001] [Indexed: 12/26/2022] Open
Abstract
The translation of polioviral mRNA occurs through an internal ribosomal entry site (IRES). Several RNA-binding proteins, such as polypyrimidine tract-binding protein (PTB) and poly(rC)-binding protein (PCBP), are required for the poliovirus IRES-dependent translation. Here we report that a poliovirus protein, 3C(pro) (and/or 3CD(pro)), cleaves PTB isoforms (PTB1, PTB2, and PTB4). Three 3C(pro) target sites (one major target site and two minor target sites) exist in PTBs. PTB fragments generated by poliovirus infection are redistributed to the cytoplasm from the nucleus, where most of the intact PTBs are localized. Moreover, these PTB fragments inhibit polioviral IRES-dependent translation in a cell-based assay system. We speculate that the proteolytic cleavage of PTBs may contribute to the molecular switching from translation to replication of polioviral RNA.
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Affiliation(s)
- Sung Hoon Back
- NRL, Department of Life Science, Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Korea
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Kuninger DT, Izumi T, Papaconstantinou J, Mitra S. Human AP-endonuclease 1 and hnRNP-L interact with a nCaRE-like repressor element in the AP-endonuclease 1 promoter. Nucleic Acids Res 2002; 30:823-9. [PMID: 11809897 PMCID: PMC100287 DOI: 10.1093/nar/30.3.823] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The major human AP-endonuclease 1 (APE1) is a multifunctional protein that plays a central role in the repair of damaged DNA by acting as a dual-function nuclease in the base excision repair pathway. This enzyme was also independently identified as a redox activator of AP-1 DNA-binding activity and has subsequently been shown to activate a variety of transcription factors via a redox mechanism. In a third distinct role, APE1 was identified as a component of a trans-acting complex that acts as a repressor by binding to the negative calcium responsive elements (nCaRE)-A and nCaRE-B, which were first discovered in the promoter of the human parathyroid gene and later in the APE1 promoter itself. Here we show that the nuclear protein complex which binds to the nCaRE-B2 of the hAPE1 gene contains APE1 itself and the heterogeneous nuclear ribonucleoprotein L (hnRNP-L). The interaction between the APE1 and hnRNP-L proteins does not require the presence of nCaRE-B2. Our results support the possibility that the APE1 gene is down-regulated by its own product, which would be the first such example of the regulation of a DNA repair enzyme, and identify a novel function of hnRNP-L in transcriptional regulation.
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Affiliation(s)
- David T Kuninger
- Department of Human Biological Chemistry and Genetics and Sealy Center for Molecular Science, University of Texas Medical Branch, 6.136 Medical Research Building, Route 1079, Galveston, TX 77555, USA
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Yuan X, Davydova N, Conte MR, Curry S, Matthews S. Chemical shift mapping of RNA interactions with the polypyrimidine tract binding protein. Nucleic Acids Res 2002; 30:456-62. [PMID: 11788707 PMCID: PMC99833 DOI: 10.1093/nar/30.2.456] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2001] [Revised: 11/16/2001] [Accepted: 11/16/2001] [Indexed: 02/05/2023] Open
Abstract
The polypyrimidine tract binding protein (PTB), a homodimer that contains four RRM-type RNA binding domains per monomer, plays important roles in both the regulation of alternative splicing and the stimulation of translation initiation as directed by the internal ribosome entry sites of certain picornaviruses. We have used chemical shift mapping experiments to probe the interactions between PTB-34, a recombinant fragment that contains the third and fourth RRM domains of the protein, and a number of short pyrimidine-rich RNA oligonucleotides. The results confirm that the RNAs interact primarily with the beta-sheet surface of PTB-34, but also reveal roles for the two long flexible linkers within the protein fragment, a result that is supported by mutagenesis experiments. The mapping indicates distinct binding preferences for RRM3 and RRM4 with the former making a particularly specific interaction with the sequence UCUUC.
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Affiliation(s)
- Xuemei Yuan
- Wolfson Laboratory, Exhibition Road, London SW7 2AY, UK
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