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Zheng Y, Wang M, Yin J, Duan Y, Wu C, Xu Z, Bu Y, Wang J, Chen Q, Zhu G, Zhao K, Zhang L, Hua R, Xu Y, Hu X, Cheng X, Xia Y. Hepatitis B virus RNAs co-opt ELAVL1 for stabilization and CRM1-dependent nuclear export. PLoS Pathog 2024; 20:e1011999. [PMID: 38306394 PMCID: PMC10866535 DOI: 10.1371/journal.ppat.1011999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 02/14/2024] [Accepted: 01/25/2024] [Indexed: 02/04/2024] Open
Abstract
Hepatitis B virus (HBV) chronically infects 296 million people worldwide, posing a major global health threat. Export of HBV RNAs from the nucleus to the cytoplasm is indispensable for viral protein translation and genome replication, however the mechanisms regulating this critical process remain largely elusive. Here, we identify a key host factor embryonic lethal, abnormal vision, Drosophila-like 1 (ELAVL1) that binds HBV RNAs and controls their nuclear export. Using an unbiased quantitative proteomics screen, we demonstrate direct binding of ELAVL1 to the HBV pregenomic RNA (pgRNA). ELAVL1 knockdown inhibits HBV RNAs posttranscriptional regulation and suppresses viral replication. Further mechanistic studies reveal ELAVL1 recruits the nuclear export receptor CRM1 through ANP32A and ANP32B to transport HBV RNAs to the cytoplasm via specific AU-rich elements, which can be targeted by a compound CMLD-2. Moreover, ELAVL1 protects HBV RNAs from DIS3+RRP6+ RNA exosome mediated nuclear RNA degradation. Notably, we find HBV core protein is dispensable for HBV RNA-CRM1 interaction and nuclear export. Our results unveil ELAVL1 as a crucial host factor that regulates HBV RNAs stability and trafficking. By orchestrating viral RNA nuclear export, ELAVL1 is indispensable for the HBV life cycle. Our study highlights a virus-host interaction that may be exploited as a new therapeutic target against chronic hepatitis B.
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Affiliation(s)
- Yingcheng Zheng
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
- School of Life Sciences, Hubei University, Wuhan, China
| | - Mengfei Wang
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Jiatong Yin
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Yurong Duan
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Chuanjian Wu
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Zaichao Xu
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Yanan Bu
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Jingjing Wang
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Quan Chen
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Guoguo Zhu
- Department of Emergency, General Hospital of Central Theater Command of People’s Liberation Army of China, Wuhan, China
| | - Kaitao Zhao
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Lu Zhang
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Rong Hua
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Yanping Xu
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Xiyu Hu
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
| | - Xiaoming Cheng
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
- Department of Pathology, Zhongnan Hospital of Wuhan University, Wuhan, China
- Hubei Clinical Center and Key Laboratory of Intestinal and Colorectal Diseases, Wuhan, China
- Hubei Jiangxia Laboratory, Wuhan, China
| | - Yuchen Xia
- State Key Laboratory of Virology and Hubei Province Key Laboratory of Allergy and Immunology, Institute of Medical Virology, TaiKang Center for Life and Medical Sciences, TaiKang Medical School, Wuhan University, Wuhan, China
- Hubei Jiangxia Laboratory, Wuhan, China
- Pingyuan Laboratory, Henan, China
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Palazzo AF, Qiu Y, Kang YM. mRNA nuclear export: how mRNA identity features distinguish functional RNAs from junk transcripts. RNA Biol 2024; 21:1-12. [PMID: 38091265 PMCID: PMC10732640 DOI: 10.1080/15476286.2023.2293339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2023] [Indexed: 12/18/2023] Open
Abstract
The division of the cellular space into nucleoplasm and cytoplasm promotes quality control mechanisms that prevent misprocessed mRNAs and junk RNAs from gaining access to the translational machinery. Here, we explore how properly processed mRNAs are distinguished from both misprocessed mRNAs and junk RNAs by the presence or absence of various 'identity features'.
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Affiliation(s)
| | - Yi Qiu
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Yoon Mo Kang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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3
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Guo J, Zhu Y, Ma X, Shang G, Liu B, Zhang K. Virus Infection and mRNA Nuclear Export. Int J Mol Sci 2023; 24:12593. [PMID: 37628773 PMCID: PMC10454920 DOI: 10.3390/ijms241612593] [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: 04/21/2023] [Revised: 07/29/2023] [Accepted: 08/03/2023] [Indexed: 08/27/2023] Open
Abstract
Gene expression in eukaryotes begins with transcription in the nucleus, followed by the synthesis of messenger RNA (mRNA), which is then exported to the cytoplasm for its translation into proteins. Along with transcription and translation, mRNA export through the nuclear pore complex (NPC) is an essential regulatory step in eukaryotic gene expression. Multiple factors regulate mRNA export and hence gene expression. Interestingly, proteins from certain types of viruses interact with these factors in infected cells, and such an interaction interferes with the mRNA export of the host cell in favor of viral RNA export. Thus, these viruses hijack the host mRNA nuclear export mechanism, leading to a reduction in host gene expression and the downregulation of immune/antiviral responses. On the other hand, the viral mRNAs successfully evade the host surveillance system and are efficiently exported from the nucleus to the cytoplasm for translation, which enables the continuation of the virus life cycle. Here, we present this review to summarize the mechanisms by which viruses suppress host mRNA nuclear export during infection, as well as the key strategies that viruses use to facilitate their mRNA nuclear export. These studies have revealed new potential antivirals that may be used to inhibit viral mRNA transport and enhance host mRNA nuclear export, thereby promoting host gene expression and immune responses.
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Affiliation(s)
- Jiayin Guo
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Yaru Zhu
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Xiaoya Ma
- University of Chinese Academy of Sciences, Beijing 100049, China; (J.G.); (Y.Z.); (X.M.)
| | - Guijun Shang
- Shanxi Provincial Key Laboratory of Protein Structure Determination, Shanxi Academy of Advanced Research and Innovation, Taiyuan 030012, China;
| | - Bo Liu
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
- Shanghai Huashen Institute of Microbes and Infections, Shanghai 200052, China
| | - Ke Zhang
- Key Laboratory of Molecular Virology and Immunology, Chinese Academy of Sciences, Shanghai 200031, China
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Khan M, Hou S, Chen M, Lei H. Mechanisms of RNA export and nuclear retention. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1755. [PMID: 35978483 DOI: 10.1002/wrna.1755] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 06/21/2022] [Accepted: 07/06/2022] [Indexed: 05/13/2023]
Abstract
With the identification of huge amount of noncoding RNAs in recent years, the concept of RNA localization has extended from traditional mRNA export to RNA export of mRNA and ncRNA as well as nuclear retention of ncRNA. This review aims to summarize the recent findings from studies on the mechanisms of export of different RNAs and nuclear retention of some lncRNAs in higher eukaryotes, with a focus on splicing-dependent TREX recruitment for the export of spliced mRNA and the sequence-dependent mechanism of mRNA export in the absence of splicing. In addition, evidence to support the involvement of m6 A modification in RNA export with the coordination between the methylase complex and TREX complex as well as sequence-dependent nuclear retention of lncRNA is recapitulated. Finally, a model of sequence-dependent RNA localization is proposed along with the many questions that remain to be answered. This article is categorized under: RNA Export and Localization > RNA Localization RNA Export and Localization > Nuclear Export/Import.
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Affiliation(s)
- Misbah Khan
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Shuai Hou
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Mo Chen
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
| | - Haixin Lei
- Institute of Cancer Stem Cell, Dalian Medical University, Dalian, China
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Su PY, Yen SCB, Yang CC, Chang CH, Lin WC, Shih C. Hepatitis B virus virion secretion is a CRM1-spike-mediated late event. J Biomed Sci 2022; 29:44. [PMID: 35729569 PMCID: PMC9210616 DOI: 10.1186/s12929-022-00827-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 06/16/2022] [Indexed: 11/10/2022] Open
Abstract
Background Hepatitis B virus (HBV) is a major human pathogen worldwide. To date, there is no curative treatment for chronic hepatitis B. The mechanism of virion secretion remains to be investigated. Previously, we found that nuclear export of HBc particles can be facilitated via two CRM1-specific nuclear export signals (NES) at the spike tip. Methods In this study, we used site-directed mutagenesis at the CRM1 NES, as well as treatment with CRM1 inhibitors at a low concentration, or CRM1-specific shRNA knockdown, in HBV-producing cell culture, and measured the secretion of various HBV viral and subviral particles via a native agarose gel electrophoresis assay. Separated HBV particles were characterized by Western blot analysis, and their genomic DNA contents were measured by Southern blot analysis. Secreted extracellular particles were compared with intracellular HBc capsids for DNA synthesis and capsid formation. Virion secretion and the in vivo interactions among HBc capsids, CRM1 and microtubules, were examined by proximity ligation assay, immunofluorescence microscopy, and nocodazole treatment. Results We report here that the tip of spike of HBV core (HBc) particles (capsids) contains a complex sensor for secretion of both HBV virions and naked capsids. HBV virion secretion is closely associated with HBc nuclear export in a CRM1-dependent manner. At the conformationally flexible spike tips of HBc particles, NES motifs overlap extensively with motifs important for secretion of HBV virions and naked capsids. Conclusions We provided experimental evidence that virions and naked capsids can egress via two distinct, yet overlapping, pathways. Unlike the secretion of naked capsids, HBV virion secretion is highly CRM1- and microtubule-dependent. CRM1 is well known for its involvement in nuclear transport in literature. To our knowledge, this is the first report that CRM1 is required for virion secretion. CRM1 inhibitors could be a promising therapeutic candidate for chronic HBV patients in clinical medicine. Supplementary Information The online version contains supplementary material available at 10.1186/s12929-022-00827-w.
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Affiliation(s)
- Pei-Yi Su
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, No.100, Shih-Chuan 1st Road, Sanmin, 80708, Kaohsiung, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Shin-Chwen Bruce Yen
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, No.100, Shih-Chuan 1st Road, Sanmin, 80708, Kaohsiung, Taiwan.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Ching-Chun Yang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chih-Hsu Chang
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Wen-Chang Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chiaho Shih
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, No.100, Shih-Chuan 1st Road, Sanmin, 80708, Kaohsiung, Taiwan. .,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
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6
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Zhou J, Huang S, Fan B, Niu B, Guo R, Gu J, Gao S, Li B. iTRAQ-based proteome analysis of porcine group A rotavirus-infected porcine IPEC-J2 intestinal epithelial cells. J Proteomics 2021; 248:104354. [PMID: 34418579 DOI: 10.1016/j.jprot.2021.104354] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 07/20/2021] [Accepted: 08/10/2021] [Indexed: 11/25/2022]
Abstract
Porcine rotavirus (PoRV), particularly group A, is one of the most important swine pathogens, causing substantial economic losses in the animal husbandry industry. To improve understanding of host responses to PoRV infection, we applied isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to quantitatively identify the differentially expressed proteins in PoRV-infected IPEC-J2 cells and confirmed the differentially accumulated proteins (DAPs) expression differences by performing RT-qPCR and Western blot analysis. Herein, in PoRV- and mock-infected IPEC-J2 cells, relative quantitative data were identified for 4724 proteins, 223 of which were DAPs (125 up-accumulated and 98 down-accumulated). Bioinformatics analyses further revealed that a majority of the DAPs are involved in numerous crucial biological processes and signaling pathways, such as metabolic process, immune system process, amino acid metabolism, energy metabolism, immune system, MHC class I peptide loading complex, Hippo signaling pathway, Th1 and Th2 cell differentiation, antigen processing and presentation, and tubule bicarbonate reclamation. The cellular localization prediction analysis indicated that these DAPs may be located in the Golgi apparatus, nucleus, peroxisomal, cytoplasm, mitochondria, extracellular, plasma membrane, and endoplasmic reticulum (ER). Expression levels of three up-accumulated (VAMP4, IKBKE, and TJP3) or two down-accumulated (SOD3 and DHX9) DAPs upon PoRV infection, were further validated by RT-qPCR and Western blot analysis. Collectively, this work is the first time to investigate the protein profile of PoRV-infected IPEC-J2 cells using quantitative proteomics; these findings provide valuable information to better understand the mechanisms underlying the host responses to PoRV infection in piglets. SIGNIFICANCE: The proteomics analysis of this study uncovered the target associated with PoRV-induced innate immune response or cellular damage, and provided relevant insights into the molecular functions, biological processes, and signaling pathway in these targets. Out of these 223 DAPs, the expression levels of three up-accumulated (VAMP4, IKBKE, and TJP3) and two down-accumulated (SOD3 and DHX9) DAPs upon PoRV infection, have been further validated using RT-qPCR and Western blot analysis. These outcomes could uncover how PoRV manipulated the cellular machinery, which could further our understanding of PoRV pathogenesis in piglets.
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Affiliation(s)
- Jinzhu Zhou
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, Jiangsu, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, PR China
| | - Shimeng Huang
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, Jiangsu, China
| | - Baochao Fan
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, Jiangsu, China; School of Life Sciences, Jiangsu University, Zhenjiang 212013, China
| | - Beibei Niu
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, Jiangsu, China; College of Veterinary Medicine, Nanjing Agricultural University, No.1 Wei-gang, Nanjing 210095, China
| | - Rongli Guo
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, Jiangsu, China
| | - Jun Gu
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, Jiangsu, China; School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China
| | - Song Gao
- Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, PR China
| | - Bin Li
- Institute of Veterinary Medicine, Jiangsu Academy of Agricultural Sciences, Key Laboratory of Veterinary Biological Engineering and Technology, Ministry of Agriculture, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, Jiangsu, China; Jiangsu Co-Innovation Center for the Prevention and Control of Important Animal Infectious Disease and Zoonose, Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou 225009, PR China; School of Food and Biological Engineering, Jiangsu University, Zhenjiang 212013, China; School of Life Sciences, Jiangsu University, Zhenjiang 212013, China.
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7
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Host Poly(A) Polymerases PAPD5 and PAPD7 Provide Two Layers of Protection That Ensure the Integrity and Stability of Hepatitis B Virus RNA. J Virol 2021; 95:e0057421. [PMID: 34191584 PMCID: PMC8387043 DOI: 10.1128/jvi.00574-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Noncanonical poly(A) polymerases PAPD5 and PAPD7 (PAPD5/7) stabilize hepatitis B virus (HBV) RNA via the interaction with the viral posttranscriptional regulatory element (PRE), representing new antiviral targets to control HBV RNA metabolism, hepatitis B surface antigen (HBsAg) production, and viral replication. Inhibitors targeting these proteins are being developed as antiviral therapies; therefore, it is important to understand how PAPD5/7 coordinate to stabilize HBV RNA. Here, we utilized a potent small-molecule AB-452 as a chemical probe, along with genetic analyses to dissect the individual roles of PAPD5/7 in HBV RNA stability. AB-452 inhibits PAPD5/7 enzymatic activities and reduces HBsAg both in vitro (50% effective concentration [EC50] ranged from 1.4 to 6.8 nM) and in vivo by 0.94 log10. Our genetic studies demonstrate that the stem-loop alpha sequence within PRE is essential for both maintaining HBV poly(A) tail integrity and determining sensitivity toward the inhibitory effect of AB-452. Although neither single knockout (KO) of PAPD5 nor PAPD7 reduces HBsAg RNA and protein production, PAPD5 KO does impair poly(A) tail integrity and confers partial resistance to AB-452. In contrast, PAPD7 KO did not result in any measurable changes within the HBV poly(A) tails, but cells with both PAPD5 and PAPD7 KO show reduced HBsAg production and conferred complete resistance to AB-452 treatment. Our results indicate that PAPD5 plays a dominant role in stabilizing viral RNA by protecting the integrity of its poly(A) tail, while PAPD7 serves as a second line of protection. These findings inform PAPD5-targeted therapeutic strategies and open avenues for further investigating PAPD5/7 in HBV replication. IMPORTANCE Chronic hepatitis B affects more than 250 million patients and is a major public health concern worldwide. HBsAg plays a central role in maintaining HBV persistence, and as such, therapies that aim at reducing HBsAg through destabilizing or degrading HBV RNA have been extensively investigated. Besides directly degrading HBV transcripts through antisense oligonucleotides or RNA silencing technologies, small-molecule compounds targeting host factors such as the noncanonical poly(A) polymerase PAPD5 and PAPD7 have been reported to interfere with HBV RNA metabolism. Herein, our antiviral and genetic studies using relevant HBV infection and replication models further characterize the interplays between the cis element within the viral sequence and the trans elements from the host factors. PAPD5/7-targeting inhibitors, with oral bioavailability, thus represent an opportunity to reduce HBsAg through destabilizing HBV RNA.
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Kubina J, Geldreich A, Gales JP, Baumberger N, Bouton C, Ryabova LA, Grasser KD, Keller M, Dimitrova M. Nuclear export of plant pararetrovirus mRNAs involves the TREX complex, two viral proteins and the highly structured 5' leader region. Nucleic Acids Res 2021; 49:8900-8922. [PMID: 34370034 PMCID: PMC8421220 DOI: 10.1093/nar/gkab653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 07/09/2021] [Accepted: 07/22/2021] [Indexed: 11/13/2022] Open
Abstract
In eukaryotes, the major nuclear export pathway for mature mRNAs uses the dimeric receptor TAP/p15, which is recruited to mRNAs via the multisubunit TREX complex, comprising the THO core and different export adaptors. Viruses that replicate in the nucleus adopt different strategies to hijack cellular export factors and achieve cytoplasmic translation of their mRNAs. No export receptors are known in plants, but Arabidopsis TREX resembles the mammalian complex, with a conserved hexameric THO core associated with ALY and UIEF proteins, as well as UAP56 and MOS11. The latter protein is an orthologue of mammalian CIP29. The nuclear export mechanism for viral mRNAs has not been described in plants. To understand this process, we investigated the export of mRNAs of the pararetrovirus CaMV in Arabidopsis and demonstrated that it is inhibited in plants deficient in ALY, MOS11 and/or TEX1. Deficiency for these factors renders plants partially resistant to CaMV infection. Two CaMV proteins, the coat protein P4 and reverse transcriptase P5, are important for nuclear export. P4 and P5 interact and co-localise in the nucleus with the cellular export factor MOS11. The highly structured 5′ leader region of 35S RNAs was identified as an export enhancing element that interacts with ALY1, ALY3 and MOS11 in vitro.
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Affiliation(s)
- Julie Kubina
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Angèle Geldreich
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Jón Pol Gales
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Nicolas Baumberger
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Clément Bouton
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Lyubov A Ryabova
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Klaus D Grasser
- Cell Biology & Plant Biochemistry, Biochemistry Centre, University of Regensburg, D-93053 Regensburg, Germany
| | - Mario Keller
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
| | - Maria Dimitrova
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, Strasbourg, France
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9
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Khan M, Hou S, Azam S, Lei H. Sequence-dependent recruitment of SRSF1 and SRSF7 to intronless lncRNA NKILA promotes nuclear export via the TREX/TAP pathway. Nucleic Acids Res 2021; 49:6420-6436. [PMID: 34096602 PMCID: PMC8216466 DOI: 10.1093/nar/gkab445] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 05/03/2021] [Accepted: 05/07/2021] [Indexed: 12/19/2022] Open
Abstract
The TREX-TAP pathway is vital for mRNA export. For spliced mRNA, the TREX complex is recruited during splicing; however, for intronless mRNA, recruitment is sequence dependent. However, the export of cytoplasmic long noncoding RNA (lncRNA) is poorly characterized. We report the identification of a cytoplasmic accumulation region (CAR-N) in the intronless lncRNA, NKILA. CAR-N removal led to strong nuclear retention of NKILA, and CAR-N insertion promoted the export of cDNA transcripts. In vitro RNP purification via CAR-N, mass spectrometry, and siRNA screening revealed that SRSF1 and SRSF7 were vital to NKILA export, and identified a cluster of SRSF1/7 binding sites within a 55 nucleotide sequence in CAR-N. Significant nuclear enrichment of NKILA was observed for NKILA lacking CAR-N or the cluster of binding sites in knock-in models. Depletion of TREX-TAP pathway components resulted in strong nuclear retention of NKILA. RNA and protein immunoprecipitation verified that SRSF1/7 were bound to NKILA and interacted with UAP56 and ALYREF. Moreover, NKILA lacking CAR-N was unable to inhibit breast cancer cell migration. We concluded that the binding of SRSF1/7 to clustered motifs in CAR-N facilitated TREX recruitment, promoting the export of NKILA, and confirmed the importance of NKILA localization to its function.
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Affiliation(s)
- Misbah Khan
- Institute of Cancer Stem Cell, Cancer Center, Dalian Medical University, 9 West Section, Lvshun South Rd, Dalian 116044, P.R. China
| | - Shuai Hou
- Institute of Cancer Stem Cell, Cancer Center, Dalian Medical University, 9 West Section, Lvshun South Rd, Dalian 116044, P.R. China.,School of Food Science and Technology, Dalian Polytechnic University, Dalian 1160343, P.R. China
| | - Sikandar Azam
- Institute of Cancer Stem Cell, Cancer Center, Dalian Medical University, 9 West Section, Lvshun South Rd, Dalian 116044, P.R. China.,Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan, USA
| | - Haixin Lei
- Institute of Cancer Stem Cell, Cancer Center, Dalian Medical University, 9 West Section, Lvshun South Rd, Dalian 116044, P.R. China
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10
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ARS2/SRRT: at the nexus of RNA polymerase II transcription, transcript maturation and quality control. Biochem Soc Trans 2021; 49:1325-1336. [PMID: 34060620 DOI: 10.1042/bst20201008] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/04/2021] [Accepted: 05/06/2021] [Indexed: 01/26/2023]
Abstract
ARS2/SRRT is an essential eukaryotic protein that has emerged as a critical factor in the sorting of functional from non-functional RNA polymerase II (Pol II) transcripts. Through its interaction with the Cap Binding Complex (CBC), it associates with the cap of newly made RNAs and acts as a hub for competitive exchanges of protein factors that ultimately determine the fate of the associated RNA. The central position of the protein within the nuclear gene expression machinery likely explains why its depletion causes a broad range of phenotypes, yet an exact function of the protein remains elusive. Here, we consider the literature on ARS2/SRRT with the attempt to garner the threads into a unifying working model for ARS2/SRRT function at the nexus of Pol II transcription, transcript maturation and quality control.
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11
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Gales JP, Kubina J, Geldreich A, Dimitrova M. Strength in Diversity: Nuclear Export of Viral RNAs. Viruses 2020; 12:E1014. [PMID: 32932882 PMCID: PMC7551171 DOI: 10.3390/v12091014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 09/03/2020] [Accepted: 09/09/2020] [Indexed: 12/11/2022] Open
Abstract
The nuclear export of cellular mRNAs is a complex process that requires the orchestrated participation of many proteins that are recruited during the early steps of mRNA synthesis and processing. This strategy allows the cell to guarantee the conformity of the messengers accessing the cytoplasm and the translation machinery. Most transcripts are exported by the exportin dimer Nuclear RNA export factor 1 (NXF1)-NTF2-related export protein 1 (NXT1) and the transcription-export complex 1 (TREX1). Some mRNAs that do not possess all the common messenger characteristics use either variants of the NXF1-NXT1 pathway or CRM1, a different exportin. Viruses whose mRNAs are synthesized in the nucleus (retroviruses, the vast majority of DNA viruses, and influenza viruses) exploit both these cellular export pathways. Viral mRNAs hijack the cellular export machinery via complex secondary structures recognized by cellular export factors and/or viral adapter proteins. This way, the viral transcripts succeed in escaping the host surveillance system and are efficiently exported for translation, allowing the infectious cycle to proceed. This review gives an overview of the cellular mRNA nuclear export mechanisms and presents detailed insights into the most important strategies that viruses use to export the different forms of their RNAs from the nucleus to the cytoplasm.
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Affiliation(s)
- Jón Pol Gales
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
| | - Julie Kubina
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
- SVQV UMR-A 1131, INRAE, Université de Strasbourg, F-68000 Colmar, France
| | - Angèle Geldreich
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
| | - Maria Dimitrova
- Institut de Biologie Moléculaire des Plantes, The French National Center for Scientific Research (CNRS) UPR2357, Université de Strasbourg, F-67084 Strasbourg, France; (J.P.G.); (J.K.); (A.G.)
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12
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Viral hijacking of the TENT4-ZCCHC14 complex protects viral RNAs via mixed tailing. Nat Struct Mol Biol 2020; 27:581-588. [PMID: 32451488 DOI: 10.1038/s41594-020-0427-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 04/03/2020] [Indexed: 12/20/2022]
Abstract
TENT4 enzymes generate 'mixed tails' of diverse nucleotides at 3' ends of RNAs via nontemplated nucleotide addition to protect messenger RNAs from deadenylation. Here we discover extensive mixed tailing in transcripts of hepatitis B virus (HBV) and human cytomegalovirus (HCMV), generated via a similar mechanism exploiting the TENT4-ZCCHC14 complex. TAIL-seq on HBV and HCMV RNAs revealed that TENT4A and TENT4B are responsible for mixed tailing and protection of viral poly(A) tails. We find that the HBV post-transcriptional regulatory element (PRE), specifically the CNGGN-type pentaloop, is critical for TENT4-dependent regulation. HCMV uses a similar pentaloop, an interesting example of convergent evolution. This pentaloop is recognized by the sterile alpha motif domain-containing ZCCHC14 protein, which in turn recruits TENT4. Overall, our study reveals the mechanism of action of PRE, which has been widely used to enhance gene expression, and identifies the TENT4-ZCCHC14 complex as a potential target for antiviral therapeutics.
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13
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Elahi S, Holling GA, Stablewski AB, Olejniczak SH. Improved hematopoietic differentiation of mouse embryonic stem cells through manipulation of the RNA binding protein ARS2. Stem Cell Res 2020; 43:101710. [PMID: 31986485 PMCID: PMC7406152 DOI: 10.1016/j.scr.2020.101710] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 01/09/2020] [Accepted: 01/13/2020] [Indexed: 10/25/2022] Open
Abstract
The RNA binding protein ARS2 is highly expressed in hematopoietic progenitor populations and is required for adult hematopoiesis. Recent molecular studies found that ARS2 coordinates interactions between nascent RNA polymerase II transcripts and downstream RNA processing machineries, yet how such interactions influence hematopoiesis remains largely unknown. Techniques to differentiate embryonic stem cells (ESC) to hematopoietic progenitor cells (HPC) and mature blood cells have increased molecular understanding of hematopoiesis. Taking such an in vitro approach to examine the influence of ARS2 on hematopoiesis, we found that ARS2 suppresses expression of some HSC signature genes and differentiation of ESC to a HPC population (CSMD-HPC) identified by markers expressed on bone marrow resident hematopoietic stem cells. In line with ARS2's ability to promote proliferation of cultured cells, ARS2 knockout ESC showed limited expansion and yielded less CSMD-HPC than wild-type ESC. In contrast, transient ARS2 knockdown led to doubling the number of CSMD-HPC generated per ESC without affecting further differentiation into mature T-cells. Overall, data indicate that ARS2 negatively regulates early hematopoietic differentiation of ESC, in stark contrast to its supportive role in adult hematopoiesis. Consequently, manipulation of ARS2 expression and/or function has potential utility in hematopoietic cell engineering and regenerative medicine.
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Affiliation(s)
- Seerat Elahi
- Department of Pathology and Anatomical Sciences, State University of New York at Buffalo, Buffalo, NY, United States
| | - G Aaron Holling
- Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States
| | - Aimee B Stablewski
- Department of Molecular and Cellular Biology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States
| | - Scott H Olejniczak
- Department of Pathology and Anatomical Sciences, State University of New York at Buffalo, Buffalo, NY, United States; Department of Immunology, Roswell Park Comprehensive Cancer Center, Buffalo, NY, United States.
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14
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Kanakkanthara A, Huntoon CJ, Hou X, Zhang M, Heinzen EP, O'Brien DR, Oberg AL, John Weroha S, Kaufmann SH, Karnitz LM. ZC3H18 specifically binds and activates the BRCA1 promoter to facilitate homologous recombination in ovarian cancer. Nat Commun 2019; 10:4632. [PMID: 31604914 PMCID: PMC6789141 DOI: 10.1038/s41467-019-12610-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 09/18/2019] [Indexed: 01/27/2023] Open
Abstract
Reduced BRCA1 expression causes homologous recombination (HR) repair defects in high-grade serous ovarian cancers (HGSOCs). Here, we demonstrate that BRCA1 is transcriptionally activated by a previously unknown function of ZC3H18. We show that ZC3H18 is a DNA-binding protein that interacts with an E2F site in the BRCA1 promoter where it facilitates recruitment of E2F4 to an adjacent E2F site to promote BRCA1 transcription. Consistent with ZC3H18 role in activating BRCA1 expression, ZC3H18 depletion induces BRCA1 promoter methylation, reduces BRCA1 expression, disrupts HR, and sensitizes cells to DNA crosslinkers and poly(ADP-ribose) polymerase inhibitors. Moreover, in patient-derived xenografts and primary HGSOC tumors, ZC3H18 and E2F4 mRNA levels are positively correlated with BRCA1 mRNA levels, further supporting ZC3H18 role in regulating BRCA1. Given that ZC3H18 lies within 16q24.2, a region with frequent copy number loss in HGSOC, these findings suggest that ZC3H18 copy number losses could contribute to HR defects in HGSOC.
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Affiliation(s)
- Arun Kanakkanthara
- Division of Oncology Research, Mayo Clinic, Rochester, MN, USA
- Department of Pharmacology, Mayo Clinic, Rochester, MN, USA
| | | | - Xiaonan Hou
- Division of Medical Oncology, Mayo Clinic, Rochester, MN, USA
| | - Minzhi Zhang
- Division of Medical Oncology, Mayo Clinic, Rochester, MN, USA
| | - Ethan P Heinzen
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, USA
| | - Daniel R O'Brien
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, USA
| | - Ann L Oberg
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, USA
| | - S John Weroha
- Division of Medical Oncology, Mayo Clinic, Rochester, MN, USA
| | - Scott H Kaufmann
- Division of Oncology Research, Mayo Clinic, Rochester, MN, USA
- Department of Pharmacology, Mayo Clinic, Rochester, MN, USA
| | - Larry M Karnitz
- Division of Oncology Research, Mayo Clinic, Rochester, MN, USA.
- Department of Pharmacology, Mayo Clinic, Rochester, MN, USA.
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15
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Helleboid P, Heusel M, Duc J, Piot C, Thorball CW, Coluccio A, Pontis J, Imbeault M, Turelli P, Aebersold R, Trono D. The interactome of KRAB zinc finger proteins reveals the evolutionary history of their functional diversification. EMBO J 2019; 38:e101220. [PMID: 31403225 PMCID: PMC6745500 DOI: 10.15252/embj.2018101220] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 07/03/2019] [Accepted: 07/10/2019] [Indexed: 01/24/2023] Open
Abstract
Krüppel-associated box (KRAB)-containing zinc finger proteins (KZFPs) are encoded in the hundreds by the genomes of higher vertebrates, and many act with the heterochromatin-inducing KAP1 as repressors of transposable elements (TEs) during early embryogenesis. Yet, their widespread expression in adult tissues and enrichment at other genetic loci indicate additional roles. Here, we characterized the protein interactome of 101 of the ~350 human KZFPs. Consistent with their targeting of TEs, most KZFPs conserved up to placental mammals essentially recruit KAP1 and associated effectors. In contrast, a subset of more ancient KZFPs rather interacts with factors related to functions such as genome architecture or RNA processing. Nevertheless, KZFPs from coelacanth, our most distant KZFP-encoding relative, bind the cognate KAP1. These results support a hypothetical model whereby KZFPs first emerged as TE-controlling repressors, were continuously renewed by turnover of their hosts' TE loads, and occasionally produced derivatives that escaped this evolutionary flushing by development and exaptation of novel functions.
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Affiliation(s)
| | - Moritz Heusel
- Department of BiologyInstitute of Molecular Systems BiologyETH ZurichZurichSwitzerland
| | - Julien Duc
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Cécile Piot
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Christian W Thorball
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Andrea Coluccio
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Julien Pontis
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Michaël Imbeault
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Priscilla Turelli
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
| | - Ruedi Aebersold
- Department of BiologyInstitute of Molecular Systems BiologyETH ZurichZurichSwitzerland
- Faculty of ScienceUniversity of ZurichZurichSwitzerland
| | - Didier Trono
- School of Life SciencesEcole Polytechnique Fédérale de LausanneLausanneSwitzerland
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16
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Xie Y, Ren Y. Mechanisms of nuclear mRNA export: A structural perspective. Traffic 2019; 20:829-840. [PMID: 31513326 DOI: 10.1111/tra.12691] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 08/26/2019] [Indexed: 12/28/2022]
Abstract
Export of mRNA from the nucleus to the cytoplasm is a critical process for all eukaryotic gene expression. As mRNA is synthesized, it is packaged with a myriad of RNA-binding proteins to form ribonucleoprotein particles (mRNPs). For each step in the processes of maturation and export, mRNPs must have the correct complement of proteins. Much of the mRNA export pathway revolves around the heterodimeric export receptor yeast Mex67•Mtr2/human NXF1•NXT1, which is recruited to signal the completion of nuclear mRNP assembly, mediates mRNP targeting/translocation through the nuclear pore complex (NPC), and is displaced at the cytoplasmic side of the NPC to release the mRNP into the cytoplasm. Directionality of the transport is governed by at least two DEAD-box ATPases, yeast Sub2/human UAP56 in the nucleus and yeast Dbp5/human DDX19 at the cytoplasmic side of the NPC, which respectively mediate the association and dissociation of Mex67•Mtr2/NXF1•NXT1 onto the mRNP. Here we review recent progress from structural studies of key constituents in different steps of nuclear mRNA export. These findings have laid the foundation for further studies to obtain a comprehensive mechanistic view of the mRNA export pathway.
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Affiliation(s)
- Yihu Xie
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Yi Ren
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee
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17
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Fan J, Kuai B, Wang K, Wang L, Wang Y, Wu X, Chi B, Li G, Cheng H. mRNAs are sorted for export or degradation before passing through nuclear speckles. Nucleic Acids Res 2019; 46:8404-8416. [PMID: 30032211 PMCID: PMC6144872 DOI: 10.1093/nar/gky650] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 07/10/2018] [Indexed: 12/14/2022] Open
Abstract
A significant fraction of mRNAs are degraded by the nuclear exosome in normal cells. Here, we studied where and when these exosome target mRNAs are sorted away from properly exported ones in the cells. We show that upon exosome inactivation, polyA RNAs are apparently accumulated in nuclear foci that are distinct from nuclear speckles (NSs), and provide several lines of evidence supporting that these polyA RNAs mainly correspond to accumulating exosome target mRNAs. These results suggest that exosomal mRNA degradation mostly occurs outside of NSs. In support of this possibility, targeting exosome target mRNAs to NSs stabilizes them by preventing exosomal degradation. Furthermore, inhibiting mRNA release from NSs does not attenuate exosomal degradation in normal cells, and results in polyA RNA accumulation both inside and outside of NSs in exosome inactivated cells, suggesting that passage through NSs is not required for sorting mRNAs for degradation or export. Indeed, exosome target mRNAs that normally do not enter NSs are exported upon exosome inactivation. Together, our data suggest that exosome target mRNAs are mainly degraded in the nucleoplasm before entering NSs and rapid removal of these mRNAs is important for preventing their nuclear export.
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Affiliation(s)
- Jing Fan
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Bin Kuai
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ke Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Lantian Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Yimin Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xudong Wu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Binkai Chi
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Hong Cheng
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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18
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Viphakone N, Sudbery I, Griffith L, Heath CG, Sims D, Wilson SA. Co-transcriptional Loading of RNA Export Factors Shapes the Human Transcriptome. Mol Cell 2019; 75:310-323.e8. [PMID: 31104896 PMCID: PMC6675937 DOI: 10.1016/j.molcel.2019.04.034] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 02/25/2019] [Accepted: 04/29/2019] [Indexed: 11/29/2022]
Abstract
During gene expression, RNA export factors are mainly known for driving nucleo-cytoplasmic transport. While early studies suggested that the exon junction complex (EJC) provides a binding platform for them, subsequent work proposed that they are only recruited by the cap binding complex to the 5′ end of RNAs, as part of TREX. Using iCLIP, we show that the export receptor Nxf1 and two TREX subunits, Alyref and Chtop, are recruited to the whole mRNA co-transcriptionally via splicing but before 3′ end processing. Consequently, Alyref alters splicing decisions and Chtop regulates alternative polyadenylation. Alyref is recruited to the 5′ end of RNAs by CBC, and our data reveal subsequent binding to RNAs near EJCs. We demonstrate that eIF4A3 stimulates Alyref deposition not only on spliced RNAs close to EJC sites but also on single-exon transcripts. Our study reveals mechanistic insights into the co-transcriptional recruitment of mRNA export factors and how this shapes the human transcriptome. 5′ cap binding complex CBC acts as a transient landing pad for Alyref Alyref is deposited upstream of the exon-exon junction next to the EJC Alyref can be deposited on introns and regulate splicing Chtop is mainly deposited on 3′ UTRs and influences poly(A) site choices
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Affiliation(s)
- Nicolas Viphakone
- Sheffield Institute For Nucleic Acids (SInFoNiA) and Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
| | - Ian Sudbery
- Sheffield Institute For Nucleic Acids (SInFoNiA) and Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Llywelyn Griffith
- Sheffield Institute For Nucleic Acids (SInFoNiA) and Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - Catherine G Heath
- Sheffield Institute For Nucleic Acids (SInFoNiA) and Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
| | - David Sims
- MRC Computational Genomics Analysis and Training Programme (CGAT), MRC Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, OX3 9DS UK
| | - Stuart A Wilson
- Sheffield Institute For Nucleic Acids (SInFoNiA) and Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
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19
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Winczura K, Schmid M, Iasillo C, Molloy KR, Harder LM, Andersen JS, LaCava J, Jensen TH. Characterizing ZC3H18, a Multi-domain Protein at the Interface of RNA Production and Destruction Decisions. Cell Rep 2019; 22:44-58. [PMID: 29298432 PMCID: PMC5770337 DOI: 10.1016/j.celrep.2017.12.037] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 11/08/2017] [Accepted: 12/11/2017] [Indexed: 12/25/2022] Open
Abstract
Nuclear RNA metabolism is influenced by protein complexes connecting to both RNA-productive and -destructive pathways. The ZC3H18 protein binds the cap-binding complex (CBC), universally present on capped RNAs, while also associating with the nuclear exosome targeting (NEXT) complex, linking to RNA decay. To dissect ZC3H18 function, we conducted interaction screening and mutagenesis of the protein, which revealed a phosphorylation-dependent isoform. Surprisingly, the modified region of ZC3H18 associates with core histone proteins. Further examination of ZC3H18 function, by genome-wide analyses, demonstrated its impact on transcription of a subset of protein-coding genes. This activity requires the CBC-interacting domain of the protein, with some genes being also dependent on the NEXT- and/or histone-interacting domains. Our data shed light on the domain requirements of a protein positioned centrally in nuclear RNA metabolism, and they suggest that post-translational modification may modulate its function. ZC3H18 uses separate domains for binding to CBCA, NEXT, and histones ZC3H18 interacts with histones in a phosphorylation-dependent manner RNA sequencing reveals a role for ZC3H18 in mRNA production CBCA-binding domain is important for ZC3H18’s role in RNA production and decay
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Affiliation(s)
- Kinga Winczura
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark; Laboratory of Cellular and Structural Biology, Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Manfred Schmid
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark
| | - Claudia Iasillo
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark
| | - Kelly R Molloy
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Lea Mørch Harder
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - Jens S Andersen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark
| | - John LaCava
- Laboratory of Cellular and Structural Biology, Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Institute for Systems Genetics, Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Torben Heick Jensen
- Department of Molecular Biology and Genetics, Aarhus University, C.F. Møllers Allé 3, Building 1130, 8000 Aarhus C, Denmark.
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20
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Wang J, Chen J, Wu G, Zhang H, Du X, Chen S, Zhang L, Wang K, Fan J, Gao S, Wu X, Zhang S, Kuai B, Zhao P, Chi B, Wang L, Li G, Wong CCL, Zhou Y, Li J, Yun C, Cheng H. NRDE2 negatively regulates exosome functions by inhibiting MTR4 recruitment and exosome interaction. Genes Dev 2019; 33:536-549. [PMID: 30842217 PMCID: PMC6499326 DOI: 10.1101/gad.322602.118] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 02/05/2019] [Indexed: 12/28/2022]
Abstract
The exosome functions in the degradation of diverse RNA species, yet how it is negatively regulated remains largely unknown. Here, we show that NRDE2 forms a 1:1 complex with MTR4, a nuclear exosome cofactor critical for exosome recruitment, via a conserved MTR4-interacting domain (MID). Unexpectedly, NRDE2 mainly localizes in nuclear speckles, where it inhibits MTR4 recruitment and RNA degradation, and thereby ensures efficient mRNA nuclear export. Structural and biochemical data revealed that NRDE2 interacts with MTR4's key residues, locks MTR4 in a closed conformation, and inhibits MTR4 interaction with the exosome as well as proteins important for MTR4 recruitment, such as the cap-binding complex (CBC) and ZFC3H1. Functionally, MID deletion results in the loss of self-renewal of mouse embryonic stem cells. Together, our data pinpoint NRDE2 as a nuclear exosome negative regulator that ensures mRNA stability and nuclear export.
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Affiliation(s)
- Jianshu Wang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Jiyun Chen
- Department of Biophysics, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Guifen Wu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Hongling Zhang
- Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Xian Du
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Suli Chen
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Li Zhang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Ke Wang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Jing Fan
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Shuaixin Gao
- Center for Precision Medicine Multi-Omics Research, Peking University Health Science Center, Beijing 100191, China
| | - Xudong Wu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Shouxiang Zhang
- Department of Biophysics, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Bin Kuai
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Peng Zhao
- Department of Biophysics, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Binkai Chi
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Lantian Wang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Catherine C L Wong
- Center for Precision Medicine Multi-Omics Research, Peking University Health Science Center, Beijing 100191, China.,State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Yu Zhou
- Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jinsong Li
- Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Caihong Yun
- Department of Biophysics, Beijing Key Laboratory of Tumor Systems Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Hong Cheng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China.,Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
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21
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O'Sullivan C, Nickerson PEB, Krupke O, Christie J, Chen LL, Mesa-Peres M, Zhu M, Ryan B, Chow RL, Howard PL. ARS2 is required for retinal progenitor cell S-phase progression and Müller glial cell fate specification. Biochem Cell Biol 2019; 98:50-60. [PMID: 30673303 DOI: 10.1139/bcb-2018-0250] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
During a developmental period that extends postnatally in the mouse, proliferating multipotent retinal progenitor cells produce one of 7 major cell types (rod, cone, bipolar, horizontal, amacrine, ganglion, and Müller glial cells) as they exit the cell cycle in consecutive waves. Cell production in the retina is tightly regulated by intrinsic, extrinsic, spatial, and temporal cues, and is coupled to the timing of cell cycle exit. Arsenic-resistance protein 2 (ARS2, also known as SRRT) is a component of the nuclear cap-binding complex involved in RNA Polymerase II transcription, and is required for cell cycle progression. We show that postnatal retinal progenitor cells (RPCs) require ARS2 for proper progression through S phase, and ARS2 disruption leads to early exit from the cell cycle. Furthermore, we observe an increase in the proportion of cells expressing a rod photoreceptor marker, and a loss of Müller glia marker expression, indicating a role for ARS2 in regulating cell fate specification or differentiation. Knockdown of Flice Associated Huge protein (FLASH), which interacts with ARS2 and is required for cell cycle progression and 3'-end processing of replication-dependent histone transcripts, phenocopies ARS2 knockdown. These data implicate ARS2-FLASH-mediated histone mRNA processing in regulating RPC cell cycle kinetics and neuroglial cell fate specification during postnatal retinal development.
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Affiliation(s)
- Connor O'Sullivan
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | | | - Oliver Krupke
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Jennifer Christie
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Li-Li Chen
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Monica Mesa-Peres
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Minyan Zhu
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Bridget Ryan
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Robert L Chow
- Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada
| | - Perry L Howard
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8W 2Y2, Canada
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22
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Mechanism and Regulation of Co-transcriptional mRNP Assembly and Nuclear mRNA Export. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1203:1-31. [DOI: 10.1007/978-3-030-31434-7_1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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23
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Palazzo AF, Lee ES. Sequence Determinants for Nuclear Retention and Cytoplasmic Export of mRNAs and lncRNAs. Front Genet 2018; 9:440. [PMID: 30386371 PMCID: PMC6199362 DOI: 10.3389/fgene.2018.00440] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 09/14/2018] [Indexed: 11/26/2022] Open
Abstract
Eukaryotes are divided into two major compartments: the nucleus where RNA is synthesized and processed, and the cytoplasm, where mRNA is translated into proteins. Although many different RNAs are made, only a subset is allowed access to the cytoplasm, primarily RNAs involved in protein synthesis (mRNA, tRNA, and rRNA). In contrast, nuclear retained transcripts are mostly long non-coding RNAs (lncRNAs) whose role in cell physiology has been a source of much investigation in the past few years. In addition, it is likely that many non-functional RNAs, which arise by spurious transcription and misprocessing of functional RNAs, are also retained in the nucleus and degraded. In this review, the main sequence features that dictate whether any particular mRNA or lncRNA is a substrate for retention in the nucleus, or export to the cytoplasm, are discussed. Although nuclear export is promoted by RNA-splicing due to the fact that the spliceosome can help recruit export factors to the mature RNA, nuclear export does not require splicing. Indeed, most stable unspliced transcripts are well exported and associate with these same export factors in a splicing-independent manner. In contrast, nuclear retention is promoted by specialized cis-elements found in certain RNAs. This new understanding of the determinants of nuclear retention and cytoplasmic export provides a deeper understanding of how information flow is regulated in eukaryotic cells. Ultimately these processes promote the evolution of complexity in eukaryotes by shaping the genomic content through constructive neutral evolution.
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24
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Wang K, Wang L, Wang J, Chen S, Shi M, Cheng H. Intronless mRNAs transit through nuclear speckles to gain export competence. J Cell Biol 2018; 217:3912-3929. [PMID: 30194269 PMCID: PMC6219727 DOI: 10.1083/jcb.201801184] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 07/04/2018] [Accepted: 08/09/2018] [Indexed: 01/12/2023] Open
Abstract
Nuclear speckles (NSs) store splicing factors. Wang et al. show that many naturally intronless mRNAs associate with NSs and that speckle association enhances their export by facilitating TREX recruitment, suggesting that trafficking to NSs could be an important quality control step in intronless mRNA export. Nuclear speckles (NSs) serve as splicing factor storage sites. In this study, we unexpectedly found that many endogenous intronless mRNAs, which do not undergo splicing, associate with NSs. These associations do not require transcription, polyadenylation, or the polyA tail. Rather, exonic splicing enhancers present in intronless mRNAs and their binding partners, SR proteins, promote intronless mRNA localization to NSs. Significantly, speckle targeting of mRNAs promotes the recruitment of the TREX export complex and their TREX-dependent nuclear export. Furthermore, TREX, which accumulates in NSs, is required for releasing intronless mRNAs from NSs, whereas NXF1, which is mainly detected at nuclear pores, is not. Upon NXF1 depletion, the TREX protein UAP56 loses speckle concentration but coaccumulates with intronless mRNAs and polyA RNAs in the nucleoplasm, and these RNAs are trapped in NSs upon UAP56 codepletion. We propose that the export-competent messenger RNP assembly mainly occurs in NSs for intronless mRNAs and that entering NSs serves as a quality control step in mRNA export.
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Affiliation(s)
- Ke Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lantian Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Jianshu Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Suli Chen
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Min Shi
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hong Cheng
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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25
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Abstract
The nuclear RNA exosome is an essential and versatile machinery that regulates maturation and degradation of a huge plethora of RNA species. The past two decades have witnessed remarkable progress in understanding the whole picture of its RNA substrates and the structural basis of its functions. In addition to the exosome itself, recent studies focusing on associated co-factors have been elucidating how the exosome is directed towards specific substrates. Moreover, it has been gradually realized that loss-of-function of exosome subunits affect multiple biological processes such as the DNA damage response, R-loop resolution, maintenance of genome integrity, RNA export, translation and cell differentiation. In this review, we summarize the current knowledge of the mechanisms of nuclear exosome-mediated RNA metabolism and discuss their physiological significance.
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26
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Hacobian A, Hercher D. Pushing the Right Buttons: Improving Efficacy of Therapeutic DNA Vectors. TISSUE ENGINEERING PART B-REVIEWS 2017; 24:226-239. [PMID: 29264951 DOI: 10.1089/ten.teb.2017.0353] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Gene therapy represents a potent therapeutical application for regenerative medicine. So far, viral and nonviral approaches suffer from major drawbacks hindering efficient gene therapeutic applicability: the immunogenicity of viral systems on the one hand, and the low gene transfer efficiency of nonviral systems on the other hand. Therefore, there is a high demand for improvements of therapeutical systems at several levels. This review summarizes different DNA vector modifications to enhance biological efficacy and efficiency of therapeutical vectors, aiming for low toxicity, high specificity, and biological efficacy-the cornerstones for successful translation of gene therapy into the clinic. We aim to provide a step-by-step instruction to optimize their vectors to achieve the desired outcome of gene therapy. Our review provides the means to either construct a potent gene therapeutic vector de novo or to specifically address a bottleneck in the chain of events mandatory for therapeutic success. Although most of the introduced techniques can be translated into different areas, this review primarily addresses improvements for applications in transient gene therapy in the field of tissue engineering.
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Affiliation(s)
- Ara Hacobian
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Department of Molecular Biology, AUVA Research Center, The Austrian Cluster for Tissue Regeneration , Vienna, Austria
| | - David Hercher
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Department of Molecular Biology, AUVA Research Center, The Austrian Cluster for Tissue Regeneration , Vienna, Austria
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27
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Functional Analysis of Human Hub Proteins and Their Interactors Involved in the Intrinsic Disorder-Enriched Interactions. Int J Mol Sci 2017; 18:ijms18122761. [PMID: 29257115 PMCID: PMC5751360 DOI: 10.3390/ijms18122761] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/13/2017] [Accepted: 12/15/2017] [Indexed: 12/15/2022] Open
Abstract
Some of the intrinsically disordered proteins and protein regions are promiscuous interactors that are involved in one-to-many and many-to-one binding. Several studies have analyzed enrichment of intrinsic disorder among the promiscuous hub proteins. We extended these works by providing a detailed functional characterization of the disorder-enriched hub protein-protein interactions (PPIs), including both hubs and their interactors, and by analyzing their enrichment among disease-associated proteins. We focused on the human interactome, given its high degree of completeness and relevance to the analysis of the disease-linked proteins. We quantified and investigated numerous functional and structural characteristics of the disorder-enriched hub PPIs, including protein binding, structural stability, evolutionary conservation, several categories of functional sites, and presence of over twenty types of posttranslational modifications (PTMs). We showed that the disorder-enriched hub PPIs have a significantly enlarged number of disordered protein binding regions and long intrinsically disordered regions. They also include high numbers of targeting, catalytic, and many types of PTM sites. We empirically demonstrated that these hub PPIs are significantly enriched among 11 out of 18 considered classes of human diseases that are associated with at least 100 human proteins. Finally, we also illustrated how over a dozen specific human hubs utilize intrinsic disorder for their promiscuous PPIs.
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28
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Zhou T, Block T, Liu F, Kondratowicz AS, Sun L, Rawat S, Branson J, Guo F, Steuer HM, Liang H, Bailey L, Moore C, Wang X, Cuconatti A, Gao M, Lee ACH, Harasym T, Chiu T, Gotchev D, Dorsey B, Rijnbrand R, Sofia MJ. HBsAg mRNA degradation induced by a dihydroquinolizinone compound depends on the HBV posttranscriptional regulatory element. Antiviral Res 2017; 149:191-201. [PMID: 29133129 DOI: 10.1016/j.antiviral.2017.11.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 11/01/2017] [Accepted: 11/07/2017] [Indexed: 12/23/2022]
Abstract
In pursuit of novel therapeutics targeting the hepatitis B virus (HBV) infection, we evaluated a dihydroquinolizinone compound (DHQ-1) that in the nanomolar range reduced the production of virion and surface protein (HBsAg) in tissue culture. This compound also showed broad HBV genotype coverage, but was inactive against a panel of DNA and RNA viruses of other species. Oral administration of DHQ-1 in the AAV-HBV mouse model resulted in a significant reduction of serum HBsAg as soon as 4 days following the commencement of treatment. Reduction of HBV markers in both in vitro and in vivo experiments was related to the reduced amount of viral RNA including pre-genomic RNA (pgRNA) and 2.4/2.1 kb HBsAg mRNA. Nuclear run-on and subcellular fractionation experiments indicated that DHQ-1 mediated HBV RNA reduction was the result of accelerated viral RNA degradation in the nucleus, rather than the consequence of inhibition of transcription initiation. Through mutagenesis of HBsAg gene sequences, we found induction of HBsAg mRNA decay by DHQ-1 required the presence of the HBV posttranscriptional regulatory element (HPRE), with a 109 nucleotides sequence within the central region of the HPRE alpha sub-element being the most critical. Taken together, the current study shows that a small molecule can reduce the overall levels of HBV RNA, especially the HBsAg mRNA, and viral surface proteins. This may shed light on the development of a new class of HBV therapeutics.
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Affiliation(s)
- Tianlun Zhou
- Baruch S. Blumberg Institute, Department of Translational Medicine, Doylestown, PA 18902, United States.
| | - Timothy Block
- Baruch S. Blumberg Institute, Department of Translational Medicine, Doylestown, PA 18902, United States
| | - Fei Liu
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Andrew S Kondratowicz
- Arbutus BioPharma, 100 - 8900 Glenlyon Parkway, Burnaby, British Columbia V5J 5J8, Canada
| | - Liren Sun
- Baruch S. Blumberg Institute, Department of Translational Medicine, Doylestown, PA 18902, United States
| | - Siddhartha Rawat
- Baruch S. Blumberg Institute, Department of Translational Medicine, Doylestown, PA 18902, United States
| | - Jeffrey Branson
- Baruch S. Blumberg Institute, Department of Translational Medicine, Doylestown, PA 18902, United States
| | - Fang Guo
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | | | - Hongyan Liang
- Baruch S. Blumberg Institute, Department of Translational Medicine, Doylestown, PA 18902, United States
| | - Lauren Bailey
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Chris Moore
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Xiaohe Wang
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Andy Cuconatti
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Min Gao
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Amy C H Lee
- Arbutus BioPharma, 100 - 8900 Glenlyon Parkway, Burnaby, British Columbia V5J 5J8, Canada
| | - Troy Harasym
- Arbutus BioPharma, 100 - 8900 Glenlyon Parkway, Burnaby, British Columbia V5J 5J8, Canada
| | - Tim Chiu
- Arbutus BioPharma, 100 - 8900 Glenlyon Parkway, Burnaby, British Columbia V5J 5J8, Canada
| | - Dimitar Gotchev
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Bruce Dorsey
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Rene Rijnbrand
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States
| | - Michael J Sofia
- Arbutus BioPharma, 701 Veterans Circle, Warminster, PA 18974, United States.
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29
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Shi M, Zhang H, Wu X, He Z, Wang L, Yin S, Tian B, Li G, Cheng H. ALYREF mainly binds to the 5' and the 3' regions of the mRNA in vivo. Nucleic Acids Res 2017; 45:9640-9653. [PMID: 28934468 PMCID: PMC5766156 DOI: 10.1093/nar/gkx597] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 07/04/2017] [Indexed: 12/04/2022] Open
Abstract
The TREX complex (TREX) plays key roles in nuclear export of mRNAs. However, little is known about its transcriptome-wide binding targets. We used individual cross-linking and immunoprecipitation (iCLIP) to identify the binding sites of ALYREF, an mRNA export adaptor in TREX, in human cells. Consistent with previous in vitro studies, ALYREF binds to a region near the 5′ end of the mRNA in a CBP80-dependent manner. Unexpectedly, we identified PABPN1-dependent ALYREF binding near the 3′ end of the mRNA. Furthermore, the 3′ processing factor CstF64 directly interacts with ALYREF and is required for the overall binding of ALYREF on the mRNA. In addition, we found that numerous middle exons harbor ALYREF binding sites and identified ALYREF-binding motifs that promote nuclear export of intronless mRNAs. Together, our study defines enrichment of ALYREF binding sites at the 5′ and the 3′ regions of the mRNA in vivo, identifies export-promoting ALYREF-binding motifs, and reveals CstF64- and PABPN1-mediated coupling of mRNA nuclear export to 3′ processing.
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Affiliation(s)
- Min Shi
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Heng Zhang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xudong Wu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Zhisong He
- CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Lantian Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Shanye Yin
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Bin Tian
- Departartment of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Hong Cheng
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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30
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Fan J, Kuai B, Wu G, Wu X, Chi B, Wang L, Wang K, Shi Z, Zhang H, Chen S, He Z, Wang S, Zhou Z, Li G, Cheng H. Exosome cofactor hMTR4 competes with export adaptor ALYREF to ensure balanced nuclear RNA pools for degradation and export. EMBO J 2017; 36:2870-2886. [PMID: 28801509 DOI: 10.15252/embj.201696139] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 07/21/2017] [Accepted: 07/23/2017] [Indexed: 12/20/2022] Open
Abstract
The exosome is a key RNA machine that functions in the degradation of unwanted RNAs. Here, we found that significant fractions of precursors and mature forms of mRNAs and long noncoding RNAs are degraded by the nuclear exosome in normal human cells. Exosome-mediated degradation of these RNAs requires its cofactor hMTR4. Significantly, hMTR4 plays a key role in specifically recruiting the exosome to its targets. Furthermore, we provide several lines of evidence indicating that hMTR4 executes this role by directly competing with the mRNA export adaptor ALYREF for associating with ARS2, a component of the cap-binding complex (CBC), and this competition is critical for determining whether an RNA is degraded or exported to the cytoplasm. Together, our results indicate that the competition between hMTR4 and ALYREF determines exosome recruitment and functions in creating balanced nuclear RNA pools for degradation and export.
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Affiliation(s)
- Jing Fan
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Bin Kuai
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guifen Wu
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xudong Wu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Binkai Chi
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Lantian Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Ke Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhubing Shi
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Heng Zhang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - She Chen
- National Institute of Biological Sciences, Beijing, China
| | - Zhisong He
- CAS Key Laboratory of Computational Biology, CAS-MPG Partner Institute for Computational Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Siyuan Wang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Zhaocai Zhou
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Hong Cheng
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
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31
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Microinjection and Fluorescence In Situ Hybridization Assay for Studying mRNA Export in Mammalian Cells. Methods Mol Biol 2017. [PMID: 28766292 DOI: 10.1007/978-1-4939-7204-3_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Microinjection and Fluorescence in situ Hybridization (FISH) assay is a useful method for mRNA export studies, which can overcome the problems of traditional transfection in cells. Here, we describe the method of microinjection and FISH assay applied in investigation of mRNA export. By this method we can estimate the mRNA export kinetics, examining mRNA export in cells with low transfection efficiencies, and observing nuclear export of aberrant RNAs.
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32
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Lee ES, Palazzo AF. Assessing mRNA nuclear export in mammalian cells by microinjection. Methods 2017; 126:76-85. [DOI: 10.1016/j.ymeth.2017.05.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 05/23/2017] [Accepted: 05/29/2017] [Indexed: 11/17/2022] Open
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33
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Abstract
TRanscription and EXport (TREX) is a conserved multisubunit complex essential for embryogenesis, organogenesis and cellular differentiation throughout life. By linking transcription, mRNA processing and export together, it exerts a physiologically vital role in the gene expression pathway. In addition, this complex prevents DNA damage and regulates the cell cycle by ensuring optimal gene expression. As the extent of TREX activity in viral infections, amyotrophic lateral sclerosis and cancer emerges, the need for a greater understanding of TREX function becomes evident. A complete elucidation of the composition, function and interactions of the complex will provide the framework for understanding the molecular basis for a variety of diseases. This review details the known composition of TREX, how it is regulated and its cellular functions with an emphasis on mammalian systems.
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Björk P, Wieslander L. Integration of mRNP formation and export. Cell Mol Life Sci 2017; 74:2875-2897. [PMID: 28314893 PMCID: PMC5501912 DOI: 10.1007/s00018-017-2503-3] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/06/2017] [Accepted: 03/07/2017] [Indexed: 12/13/2022]
Abstract
Expression of protein-coding genes in eukaryotes relies on the coordinated action of many sophisticated molecular machineries. Transcription produces precursor mRNAs (pre-mRNAs) and the active gene provides an environment in which the pre-mRNAs are processed, folded, and assembled into RNA–protein (RNP) complexes. The dynamic pre-mRNPs incorporate the growing transcript, proteins, and the processing machineries, as well as the specific protein marks left after processing that are essential for export and the cytoplasmic fate of the mRNPs. After release from the gene, the mRNPs move by diffusion within the interchromatin compartment, making up pools of mRNPs. Here, splicing and polyadenylation can be completed and the mRNPs recruit the major export receptor NXF1. Export competent mRNPs interact with the nuclear pore complex, leading to export, concomitant with compositional and conformational changes of the mRNPs. We summarize the integrated nuclear processes involved in the formation and export of mRNPs.
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Affiliation(s)
- Petra Björk
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
| | - Lars Wieslander
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, 106 91 Stockholm, Sweden
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Schumann S, Whitehouse A. Targeting the human TREX complex to prevent herpesvirus replication: what is new? Future Virol 2017. [DOI: 10.2217/fvl-2017-0006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Sophie Schumann
- School of Molecular & Cellular Biology, & Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Adrian Whitehouse
- School of Molecular & Cellular Biology, & Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK
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Rodor J, Pan Q, Blencowe BJ, Eyras E, Cáceres JF. The RNA-binding profile of Acinus, a peripheral component of the exon junction complex, reveals its role in splicing regulation. RNA (NEW YORK, N.Y.) 2016; 22:1411-26. [PMID: 27365209 PMCID: PMC4986896 DOI: 10.1261/rna.057158.116] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/24/2016] [Indexed: 05/21/2023]
Abstract
Acinus (apoptotic chromatin condensation inducer in the nucleus) is an RNA-binding protein (RBP) originally identified for its role in apoptosis. It was later found to be an auxiliary component of the exon junction complex (EJC), which is deposited at exon junctions as a consequence of pre-mRNA splicing. To uncover the cellular functions of Acinus and investigate its role in splicing, we mapped its endogenous RNA targets using the cross-linking immunoprecipitation protocol (iCLIP). We observed that Acinus binds to pre-mRNAs, associating specifically to a subset of suboptimal introns, but also to spliced mRNAs. We also confirmed the presence of Acinus as a peripheral factor of the EJC. RNA-seq was used to investigate changes in gene expression and alternative splicing following siRNA-mediated depletion of Acinus in HeLa cells. This analysis revealed that Acinus is preferentially required for the inclusion of specific alternative cassette exons and also controls the faithful splicing of a subset of introns. Moreover, a large number of splicing changes can be related to Acinus binding, suggesting a direct role of Acinus in exon and intron definition. In particular, Acinus regulates the splicing of DFFA/ICAD transcript, a major regulator of DNA fragmentation. Globally, the genome-wide identification of RNA targets of Acinus revealed its role in splicing regulation as well as its involvement in other cellular pathways, including cell cycle progression. Altogether, this study uncovers new cellular functions of an RBP transiently associated with the EJC.
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Affiliation(s)
- Julie Rodor
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | - Qun Pan
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada
| | - Benjamin J Blencowe
- Donnelly Centre, University of Toronto, Toronto, Ontario M5S 3E1, Canada Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Eduardo Eyras
- Universitat Pompeu Fabra, E08003, Barcelona, Spain Catalan Institution for Research and Advanced Studies (ICREA), E08010 Barcelona, Spain
| | - Javier F Cáceres
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
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Hur JK, Luo Y, Moon S, Ninova M, Marinov GK, Chung YD, Aravin AA. Splicing-independent loading of TREX on nascent RNA is required for efficient expression of dual-strand piRNA clusters in Drosophila. Genes Dev 2016; 30:840-55. [PMID: 27036967 PMCID: PMC4826399 DOI: 10.1101/gad.276030.115] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 03/07/2016] [Indexed: 11/25/2022]
Abstract
In this study, Hur et al. identified a novel function for the TREX complex, which is critical for pre-mRNA processing and mRNA nuclear export. They found that Thoc5 and other TREX components are essential for the biogenesis of noncoding RNA and delineate a novel mechanism for TREX loading on nascent RNA. The conserved THO/TREX (transcription/export) complex is critical for pre-mRNA processing and mRNA nuclear export. In metazoa, TREX is loaded on nascent RNA transcribed by RNA polymerase II in a splicing-dependent fashion; however, how TREX functions is poorly understood. Here we show that Thoc5 and other TREX components are essential for the biogenesis of piRNA, a distinct class of small noncoding RNAs that control expression of transposable elements (TEs) in the Drosophila germline. Mutations in TREX lead to defects in piRNA biogenesis, resulting in derepression of multiple TE families, gametogenesis defects, and sterility. TREX components are enriched on piRNA precursors transcribed from dual-strand piRNA clusters and colocalize in distinct nuclear foci that overlap with sites of piRNA transcription. The localization of TREX in nuclear foci and its loading on piRNA precursor transcripts depend on Cutoff, a protein associated with chromatin of piRNA clusters. Finally, we show that TREX is required for accumulation of nascent piRNA precursors. Our study reveals a novel splicing-independent mechanism for TREX loading on nascent RNA and its importance in piRNA biogenesis.
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Affiliation(s)
- Junho K Hur
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Yicheng Luo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Sungjin Moon
- Department of Life Science, University of Seoul, Seoul 130-743, Korea
| | - Maria Ninova
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Georgi K Marinov
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Yun D Chung
- Department of Life Science, University of Seoul, Seoul 130-743, Korea
| | - Alexei A Aravin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
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Zhang W, Sun J, Luo J. High Expression of Rab-like 3 (Rabl3) is Associated with Poor Survival of Patients with Non-Small Cell Lung Cancer via Repression of MAPK8/9/10-Mediated Autophagy. Med Sci Monit 2016; 22:1582-8. [PMID: 27164297 PMCID: PMC4918526 DOI: 10.12659/msm.898632] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Background Rab-like 3 (Rabl3) is a member of the Rab subfamily of small GTPases which are involved in controlling proliferation and vesicular trafficking. Recent studies suggest that Rab proteins might play a critical role in regulating cancer cell survival, but the underlying mechanisms remain largely unknown. Material/Methods We performed a bioinformatics analysis to examine the correlation between the expression level of Rabl3 and survival of non-small cell lung cancer (NSCLC) patients in three independent cohorts containing 484 patients. The function of Rabl3 was examined in NSCLC cell line A549 in vitro. Following Rabl3 knockdown, cells were stained with propidium iodine (PI) and Annexin V, followed by flow cytometry analysis (FACS) for cell death and autophagy induction. The activity of the MAPK signaling pathway was assessed by Western blotting of different MAPK phosphorylations, and modulated with different chemical inhibitors. Results High expression of Rabl3 was significantly correlated with poor survival in all three independent NSCLC cohorts. In line with this result, Rabl3 was frequently overexpressed in lung cancer cell lines as compared with normal lung fibroblast cell lines. Knockdown of Rabl3 in lung cancer cells significantly enhanced cell death accompanied with autophagy induction, as evidenced by an increased level of autophagy marker LC3-II. Interestingly, Rabl3 knockdown was associated with enhanced activation of MAPK8/9/10 but not MAPK11/12/13/14. Treatment of MAPK8/9/10-specific inhibitor SP600125, but not MAPK11/12/13/14-specific inhibitor SB203580, largely abolished Rabl3 knockdown-induced LC3-I/LC3-II conversion and autophagic cell death. Conclusions Together, these results suggest that high expression of Rabl3 might inhibit cell death in NSCLCs via repression of MAPK8/9/10-mediated autophagy.
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Affiliation(s)
- Weihua Zhang
- Department of Oncology, Medical School of Nanchang University, Nanchang, Jiangxi, China (mainland)
| | - Jian Sun
- Department of Respiration, The Fourth Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China (mainland)
| | - Junming Luo
- Department of Respiration, The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi, China (mainland)
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Lim CS, Brown CM. Hepatitis B virus nuclear export elements: RNA stem-loop α and β, key parts of the HBV post-transcriptional regulatory element. RNA Biol 2016; 13:743-7. [PMID: 27031749 DOI: 10.1080/15476286.2016.1166330] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Many viruses contain RNA elements that modulate splicing and/or promote nuclear export of their RNAs. The RNAs of the major human pathogen, hepatitis B virus (HBV) contain a large (~600 bases) composite cis-acting 'post-transcriptional regulatory element' (PRE). This element promotes expression from these naturally intronless transcripts. Indeed, the related woodchuck hepadnavirus PRE (WPRE) is used to enhance expression in gene therapy and other expression vectors. These PRE are likely to act through a combination of mechanisms, including promotion of RNA nuclear export. Functional components of both the HBV PRE and WPRE are 2 conserved RNA cis-acting stem-loop (SL) structures, SLα and SLβ. They are within the coding regions of polymerase (P) gene, and both P and X genes, respectively. Based on previous studies using mutagenesis and/or nuclear magnetic resonance (NMR), here we propose 2 covariance models for SLα and SLβ. The model for the 30-nucleotide SLα contains a G-bulge and a CNGG(U) apical loop of which the first and the fourth loop residues form a CG pair and the fifth loop residue is bulged out, as observed in the NMR structure. The model for the 23-nucleotide SLβ contains a 7-base-pair stem and a 9-nucleotide loop. Comparison of the models with other RNA structural elements, as well as similarity searches of human transcriptome and viral genomes demonstrate that SLα and SLβ are specific to HBV transcripts. However, they are well conserved among the hepadnaviruses of non-human primates, the woodchuck and ground squirrel.
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Affiliation(s)
- Chun Shen Lim
- a Biochemistry and Genetics Otago , University of Otago , Dunedin , New Zealand
| | - Chris M Brown
- a Biochemistry and Genetics Otago , University of Otago , Dunedin , New Zealand
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Kim SY, Sim CK, Tang H, Han W, Zhang K, Xu F. Acetylome study in mouse adipocytes identifies targets of SIRT1 deacetylation in chromatin organization and RNA processing. Arch Biochem Biophys 2016; 598:1-10. [PMID: 27021582 DOI: 10.1016/j.abb.2016.03.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 02/29/2016] [Accepted: 03/24/2016] [Indexed: 01/24/2023]
Abstract
SIRT1 is a key protein deacetylase that regulates cellular metabolism through lysine deacetylation on both histones and non-histone proteins. Lysine acetylation is a wide-spread post-translational modification found on many regulatory proteins and it plays an essential role in cell signaling, transcription and metabolism. In mice, SIRT1 has known protective functions during high-fat diet but the acetylome regulated by SIRT1 in adipocytes is not completely understood. Here we conducted acetylome analyses in murine adipocytes treated with small-molecule modulators that inhibit or activate the deacetylase activity of SIRT1. We identified a total of 302 acetylated peptides from 78 proteins in this study. From the list of potential SIRT1 targets, we selected seven candidates and further verified that six of them can be deacetylated by SIRT1 in-vitro. Among them, half of the SIRT1 targets are involved in regulating chromatin structure and the other half is involved in RNA processing. Our results provide a resource for further SIRT1 target validation in fat cells and suggest a potential role of SIRT1 in the regulation of chromatin structure and RNA processing, which may possibly extend to other cell types as well.
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Affiliation(s)
- Sun-Yee Kim
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), 30 Medical Drive, Singapore 117609, Singapore
| | - Choon Kiat Sim
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), 30 Medical Drive, Singapore 117609, Singapore
| | - Hui Tang
- Department of Pharmacology and Toxicology, UTMB at Galveston, TX 77554, USA
| | - Weiping Han
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, 11 Biopolis Way, Singapore 138667, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore 117596, Singapore; Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School, 8 College Road, Singapore 169857, Singapore
| | - Kangling Zhang
- Department of Pharmacology and Toxicology, UTMB at Galveston, TX 77554, USA.
| | - Feng Xu
- Singapore Institute for Clinical Sciences, Agency for Science, Technology and Research (A*STAR), 30 Medical Drive, Singapore 117609, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 8 Medical Drive, Singapore 117596, Singapore; Cardiovascular and Metabolic Disorders Program, Duke-NUS Graduate Medical School, 8 College Road, Singapore 169857, Singapore.
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Mutagenesis of ARS2 Domains To Assess Possible Roles in Cell Cycle Progression and MicroRNA and Replication-Dependent Histone mRNA Biogenesis. Mol Cell Biol 2015; 35:3753-67. [PMID: 26303529 DOI: 10.1128/mcb.00272-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 08/19/2015] [Indexed: 11/20/2022] Open
Abstract
ARS2 is a regulator of RNA polymerase II transcript processing through its role in the maturation of distinct nuclear cap-binding complex (CBC)-controlled RNA families. In this study, we examined ARS2 domain function in transcript processing. Structural modeling based on the plant ARS2 orthologue, SERRATE, revealed 2 previously uncharacterized domains in mammalian ARS2: an N-terminal domain of unknown function (DUF3546), which is also present in SERRATE, and an RNA recognition motif (RRM) that is present in metazoan ARS2 but not in plants. Both the DUF3546 and zinc finger domain (ZnF) were required for association with microRNA and replication-dependent histone mRNA. Mutations in the ZnF disrupted interaction with FLASH, a key component in histone pre-mRNA processing. Mutations targeting the Mid domain implicated it in DROSHA interaction and microRNA biogenesis. The unstructured C terminus was required for interaction with the CBC protein CBP20, while the RRM was required for cell cycle progression and for binding to FLASH. Together, our results support a bridging model in which ARS2 plays a central role in RNA recognition and processing through multiple protein and RNA interactions.
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Nuclear export of human hepatitis B virus core protein and pregenomic RNA depends on the cellular NXF1-p15 machinery. PLoS One 2014; 9:e106683. [PMID: 25360769 PMCID: PMC4215830 DOI: 10.1371/journal.pone.0106683] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 07/31/2014] [Indexed: 12/17/2022] Open
Abstract
Hepatitis B virus (HBV) core protein (HBc) can shuttle between nucleus and cytoplasm. Cytoplasm-predominant HBc is clinically associated with severe liver inflammation. Previously, we found that HBc arginine-rich domain (ARD) can associate with a host factor NXF1 (TAP) by coimmunoprecipitation. It is well known that NXF1-p15 heterodimer can serve as a major export receptor of nuclear mRNA as a ribonucleoprotein complex (RNP). In the NXF1-p15 pathway, TREX (transcription/export) complex plays an important role in coupling nuclear pre-mRNA processing with mRNA export in mammalian cells. Here, we tested the hypothesis whether HBc and HBV specific RNA can be exported via the TREX and NXF1-p15 mediated pathway. We demonstrated here that HBc can physically and specifically associate with TREX components, and the NXF1-p15 export receptor by coimmunoprecipitation. Accumulation of HBc protein in the nucleus can be induced by the interference with TREX and NXF1-p15 mediated RNA export machinery. HBV transcripts encodes a non-spliced 3.5 kb pregenomic RNA (pgRNA) which can serve as a template for reverse transcription. Cytoplasmic HBV pgRNA appeared to be reduced by siRNA treatment specific for the NXF1-p15 complex by quantitative RT-qPCR and Northern blot analyses. This result suggests that the pgRNA was also exported via the NXF1-p15 machinery. We entertain the hypothesis that HBc protein can be exported as an RNP cargo via the mRNA export pathway by hijacking the TREX and NXF1-p15 complex. In our current and previous studies, HBc is not required for pgRNA accumulation in the cytoplasm. Furthermore, HBc ARD can mediate nuclear export of a chimeric protein containing HBc ARD in a pgRNA-independent manner. Taken together, it suggests that while both pgRNA and HBc protein exports are dependent on NXF1-p15, they are using the same export machinery in a manner independent of each other.
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