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Moezpoor MR, Stevenson M. Help or Hinder: Protein Host Factors That Impact HIV-1 Replication. Viruses 2024; 16:1281. [PMID: 39205255 PMCID: PMC11360189 DOI: 10.3390/v16081281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Revised: 08/05/2024] [Accepted: 08/08/2024] [Indexed: 09/04/2024] Open
Abstract
Interactions between human immunodeficiency virus type 1 (HIV-1) and the host factors or restriction factors of its target cells determine the cell's susceptibility to, and outcome of, infection. Factors intrinsic to the cell are involved at every step of the HIV-1 replication cycle, contributing to productive infection and replication, or severely attenuating the chances of success. Furthermore, factors unique to certain cell types contribute to the differences in infection between these cell types. Understanding the involvement of these factors in HIV-1 infection is a key requirement for the development of anti-HIV-1 therapies. As the list of factors grows, and the dynamic interactions between these factors and the virus are elucidated, comprehensive and up-to-date summaries that recount the knowledge gathered after decades of research are beneficial to the field, displaying what is known so that researchers can build off the groundwork of others to investigate what is unknown. Herein, we aim to provide a review focusing on protein host factors, both well-known and relatively new, that impact HIV-1 replication in a positive or negative manner at each stage of the replication cycle, highlighting factors unique to the various HIV-1 target cell types where appropriate.
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Affiliation(s)
- Michael Rameen Moezpoor
- Department of Microbiology and Immunology, University of Miami Leonard M. Miller School of Medicine, Miami, FL 33136, USA
| | - Mario Stevenson
- Raymond F. Schinazi and Family Endowed Chair in Biomedicine; Professor of Medicine; Director, Institute of AIDS and Emerging Infectious Diseases; Department of Microbiology and Immunology, University of Miami Leonard M. Miller School of Medicine, Life Science Technology Park, 1951 NW 7th Avenue, Room 2331B, Suite 200, Miami, FL 33136, USA;
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2
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Zheng K, Chen S, Ren Z, Wang Y. Protein arginine methylation in viral infection and antiviral immunity. Int J Biol Sci 2023; 19:5292-5318. [PMID: 37928266 PMCID: PMC10620831 DOI: 10.7150/ijbs.89498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 10/10/2023] [Indexed: 11/07/2023] Open
Abstract
Protein arginine methyltransferase (PRMT)-mediated arginine methylation is an important post-transcriptional modification that regulates various cellular processes including epigenetic gene regulation, genome stability maintenance, RNA metabolism, and stress-responsive signal transduction. The varying substrates and biological functions of arginine methylation in cancer and neurological diseases have been extensively discussed, providing a rationale for targeting PRMTs in clinical applications. An increasing number of studies have demonstrated an interplay between arginine methylation and viral infections. PRMTs have been found to methylate and regulate several host cell proteins and different functional types of viral proteins, such as viral capsids, mRNA exporters, transcription factors, and latency regulators. This modulation affects their activity, subcellular localization, protein-nucleic acid and protein-protein interactions, ultimately impacting their roles in various virus-associated processes. In this review, we discuss the classification, structure, and regulation of PRMTs and their pleiotropic biological functions through the methylation of histones and non-histones. Additionally, we summarize the broad spectrum of PRMT substrates and explore their intricate effects on various viral infection processes and antiviral innate immunity. Thus, comprehending the regulation of arginine methylation provides a critical foundation for understanding the pathogenesis of viral diseases and uncovering opportunities for antiviral therapy.
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Affiliation(s)
- Kai Zheng
- School of Pharmacy, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518055, China
| | - Siyu Chen
- School of Pharmacy, Shenzhen University Medical School, Shenzhen University, Shenzhen, 518055, China
| | - Zhe Ren
- Institute of Biomedicine, College of Life Science and Technology, Guangdong Province Key Laboratory of Bioengineering Medicine, Key Laboratory of Innovative Technology Research on Natural Products and Cosmetics Raw Materials, Jinan University, Guangzhou, 510632, China
| | - Yifei Wang
- Institute of Biomedicine, College of Life Science and Technology, Guangdong Province Key Laboratory of Bioengineering Medicine, Key Laboratory of Innovative Technology Research on Natural Products and Cosmetics Raw Materials, Jinan University, Guangzhou, 510632, China
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3
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Wahl A, Al-Harthi L. HIV infection of non-classical cells in the brain. Retrovirology 2023; 20:1. [PMID: 36639783 PMCID: PMC9840342 DOI: 10.1186/s12977-023-00616-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/02/2023] [Indexed: 01/15/2023] Open
Abstract
HIV-associated neurological disorders (HAND) affect up to 50% of people living with HIV (PLWH), even in the era of combination antiretroviral therapy (cART). HIV-DNA can be detected in the cerebral spinal fluid (CSF) of approximately half of aviremic ART-suppressed PLWH and its presence is associated with poorer neurocognitive performance. HIV DNA + and HIV RNA + cells have also been observed in postmortem brain tissue of individuals with sustained cART suppression. In this review, we provide an overview of how HIV invades the brain and HIV infection of resident brain glial cells (astrocytes and microglia). We also discuss the role of resident glial cells in persistent neuroinflammation and HAND in PLWH and their potential contribution to the HIV reservoir. HIV eradication strategies that target persistently infected glia cells will likely be needed to achieve HIV cure.
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Affiliation(s)
- Angela Wahl
- grid.10698.360000000122483208International Center for the Advancement of Translational Science, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,grid.10698.360000000122483208Division of Infectious Diseases, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC USA ,grid.10698.360000000122483208Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Lena Al-Harthi
- grid.240684.c0000 0001 0705 3621Department of Microbial Pathogens and Immunity, Rush University Medical Center, Chicago, IL USA
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4
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Komiyama T, Kuroshima T, Sugasawa T, Fujita SI, Ikami Y, Hirai H, Tsushima F, Michi Y, Kayamori K, Higashino F, Harada H. High expression of Sam68 contributes to metastasis by regulating vimentin expression and a motile phenotype in oral squamous cell carcinoma. Oncol Rep 2022; 48:183. [PMID: 36082807 PMCID: PMC9478953 DOI: 10.3892/or.2022.8398] [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: 05/17/2022] [Accepted: 07/25/2022] [Indexed: 12/24/2022] Open
Abstract
The present study aimed to investigate the clinical and biological significance of Src-associated in mitosis 68 kDa (Sam68) in oral squamous cell carcinoma (OSCC). Immunohistochemical analysis was performed on tissue samples obtained from 77 patients with OSCC. Univariate analysis revealed that the high expression of Sam68 was significantly correlated with advanced pathological T stage (P=0.01), positive lymphovascular invasion (P=0.01), and pathological cervical lymph node metastasis (P<0.01). Moreover, multivariate analysis demonstrated that the high expression of Sam68 was an independent predictive factor for cervical lymph node metastasis (odds ratio, 4.39; 95% confidence interval, 1.49-14.23; P<0.01). These results indicated that high Sam68 expression contributed to tumor progression, especially cervical lymph node metastasis, in OSCC. mRNA sequencing was also performed to assess the changes in the transcriptome between OSCC cells with Sam68 knockdown and control cells with the aim of elucidating the biological roles of Sam68. Gene Ontology enrichment analysis revealed that downregulated differentially expressed genes (DEGs) were concentrated in some biological processes related to epithelial-mesenchymal transition. Among these DEGs, it was established that vimentin was particularly downregulated in these cells. It was also confirmed that Sam68 knockdown reduced the motility of OSCC cells. Furthermore, the immunohistochemical study of vimentin identified the association between vimentin expression and Sam68 expression as well as cervical lymph node metastasis. In conclusion, the present study suggested that the high expression of Sam68 may contribute to metastasis by regulating vimentin expression and a motile mesenchymal phenotype in OSCC.
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Affiliation(s)
- Takuya Komiyama
- Department of Oral and Maxillofacial Surgical Oncology, Division of Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
| | - Takeshi Kuroshima
- Department of Oral and Maxillofacial Surgical Oncology, Division of Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
| | - Takehito Sugasawa
- Laboratory of Clinical Examination/Sports Medicine, Department of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305‑8577, Japan
| | - Shin-Ichiro Fujita
- Laboratory of Clinical Examination/Sports Medicine, Department of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305‑8577, Japan
| | - Yuta Ikami
- Department of Oral and Maxillofacial Surgical Oncology, Division of Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
| | - Hideaki Hirai
- Department of Oral and Maxillofacial Surgical Oncology, Division of Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
| | - Fumihiko Tsushima
- Department of Oral and Maxillofacial Surgical Oncology, Division of Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
| | - Yasuyuki Michi
- Department of Oral and Maxillofacial Surgical Oncology, Division of Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
| | - Kou Kayamori
- Department of Oral Pathology, Division of Oral Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
| | - Fumihiro Higashino
- Department of Molecular Oncology, Faculty of Dental Medicine and Graduate School of Biomedical Science and Engineering, Hokkaido University, Sapporo, Hokkaido 060‑8586, Japan
| | - Hiroyuki Harada
- Department of Oral and Maxillofacial Surgical Oncology, Division of Health Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo‑ku, Tokyo 113‑8549, Japan
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5
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Wu Z, Peng Y, Xiong L, Wang J, Li Z, Ning K, Deng M, Wang N, Wei W, Li Z, Dong P, Yu C, Zhou F, Zhang Z. Role of Sam68 in Sunitinib induced renal cell carcinoma apoptosis. Cancer Med 2022; 11:3674-3686. [PMID: 35476809 PMCID: PMC9554455 DOI: 10.1002/cam4.4743] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 03/12/2022] [Accepted: 03/30/2022] [Indexed: 11/18/2022] Open
Abstract
Sunitinib is one of the first-line targeted drugs for metastatic renal cell carcinoma (RCC) with dual effects of antiangiogensis and proapoptosis. Sam68 (Src-associated in mitosis, 68 KDa), is found being involved in cell apoptosis. This article reveals that Sam68 impacts the sensitivity to sunitinib by mediating the apoptosis of RCC cells. Immunohistochemical staining indicated that the Sam68 expression levels in sunitinib sensitive tumor tissues were markedly higher than those in sunitinib resistant tumor tissues. Sunitinib induced RCC cell apoptosis in a concentration-dependent manner and inhibited the expression of total and phosphorylated Sam68 (p-Sam68). Downregulation of Sam68 expression inhibited RCC cell apoptosis induced by sunitinib. While upregulation of Sam68 expression could enhance apoptosis induced by sunitinib. Xenograft models showed that tumors in the Sam68-knockdown group did not shrink as much as those in the control group after treatment with sunitinib for 4 weeks. Together, our results suggest that Sam68 expression is associated with the sensitivity of ccRCC patients to sunitinib. Sam68 may promote cell apoptosis induced by sunitinib, and the Sam68 expression level may be a biomarker for predicting sunitinib sensitivity in ccRCC patients.
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Affiliation(s)
- Zeshen Wu
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Yulu Peng
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Longbin Xiong
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Jun Wang
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Zhen Li
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Kang Ning
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Minhua Deng
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Ning Wang
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Wensu Wei
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Zhiyong Li
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Pei Dong
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Chunping Yu
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Fangjian Zhou
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
| | - Zhiling Zhang
- Department of UrologySun Yat‐sen University Cancer CenterGuangzhouChina
- State Key Laboratory of Oncology in Southern ChinaGuangzhouChina
- Collaborative Innovation Center for Cancer MedicineGuangzhouChina
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6
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Klein ME, Younts TJ, Cobo CF, Buxbaum AR, Aow J, Erdjument-Bromage H, Richard S, Malinow R, Neubert TA, Singer RH, Castillo PE, Jordan BA. Sam68 Enables Metabotropic Glutamate Receptor-Dependent LTD in Distal Dendritic Regions of CA1 Hippocampal Neurons. Cell Rep 2020; 29:1789-1799.e6. [PMID: 31722197 PMCID: PMC6871770 DOI: 10.1016/j.celrep.2019.10.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 08/15/2019] [Accepted: 10/08/2019] [Indexed: 12/13/2022] Open
Abstract
The transport and translation of dendritic mRNAs by RNA-binding proteins (RBPs) allows for spatially restricted gene expression in neuronal processes. Although local translation in neuronal dendrites is now well documented, there is little evidence for corresponding effects on local synaptic function. Here, we report that the RBP Sam68 promotes the localization and translation of Arc mRNA preferentially in distal dendrites of rodent hippocampal CA1 pyramidal neurons. Consistent with Arc function in translation-dependent synaptic plasticity, we find that Sam68 knockout (KO) mice display impaired metabotropic glutamate-receptor-dependent long-term depression (mGluR-LTD) and impaired structural plasticity exclusively at distal Schaffer-collateral synapses. Moreover, by using quantitative proteomics, we find that the Sam68 interactome contains numerous regulators of mRNA translation and synaptic function. This work identifies an important player in Arc expression, provides a general framework for Sam68 regulation of protein synthesis, and uncovers a mechanism that enables the precise spatiotemporal expression of long-term plasticity throughout neurons.
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Affiliation(s)
- Matthew E Klein
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Thomas J Younts
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Carmen Freire Cobo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Adina R Buxbaum
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA; Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093, USA
| | - Jonathan Aow
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093, USA
| | - Hediye Erdjument-Bromage
- Department of Cell Biology and Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Stéphane Richard
- Segal Cancer Center, Lady Davis Institute for Medical Research and Departments of Oncology and Medicine, McGill University, Montréal, QC H3T 1E2, Canada
| | - Roberto Malinow
- Center for Neural Circuits and Behavior, Department of Neuroscience and Section for Neurobiology, Division of Biology, University of California at San Diego, San Diego, CA 92093, USA
| | - Thomas A Neubert
- Department of Cell Biology and Kimmel Center for Biology and Medicine, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
| | - Robert H Singer
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA; Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA; Janelia Research Campus of the Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Bryen A Jordan
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA; Department of Psychiatry and Behavioral Sciences, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA.
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7
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Sun D, Wen X, Wang M, Mao S, Cheng A, Yang X, Jia R, Chen S, Yang Q, Wu Y, Zhu D, Liu M, Zhao X, Zhang S, Wang Y, Xu Z, Chen Z, Zhu L, Luo Q, Liu Y, Yu Y, Zhang L, Chen X. Apoptosis and Autophagy in Picornavirus Infection. Front Microbiol 2019; 10:2032. [PMID: 31551969 PMCID: PMC6733961 DOI: 10.3389/fmicb.2019.02032] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 08/19/2019] [Indexed: 12/13/2022] Open
Abstract
Cell death is a fundamental process in maintaining cellular homeostasis, which can be either accidental or programed. Programed cell death depends on the specific signaling pathways, resulting in either lytic or non-lytic morphology. It exists in two primary forms: apoptosis and autophagic cell death. Apoptosis is a non-lytic and selective cell death program, which is executed by caspases in response to non-self or external stimuli. In contrast, autophagy is crucial for maintaining cellular homeostasis via the degradation and recycling of cellular components. These two mechanisms also function in the defense against pathogen attack. However, picornaviruses have evolved to utilize diverse strategies and target critical components to regulate the apoptotic and autophagic processes for optimal replication and the release from the host cell. Although an increasing number of investigations have shown that the apoptosis and autophagy are altered in picornavirus infection, the mechanism by which viruses take advantage of these two processes remains unknown. In this review, we discuss the mechanisms of picornavirus executes cellular apoptosis and autophagy at the molecular level and the relationship between these interactions and viral pathogenesis.
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Affiliation(s)
- Di Sun
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xingjian Wen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mingshu Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Sai Mao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Anchun Cheng
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiaoyao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Renyong Jia
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shun Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qiao Yang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ying Wu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Dekang Zhu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Mafeng Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xinxin Zhao
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Shaqiu Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yin Wang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Zhiwen Xu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Zhengli Chen
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Qihui Luo
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yunya Liu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Yanling Yu
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Ling Zhang
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.,Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
| | - Xiaoyue Chen
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, China.,Avian Disease Research Center, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China
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8
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Li GH, Henderson L, Nath A. Astrocytes as an HIV Reservoir: Mechanism of HIV Infection. Curr HIV Res 2016; 14:373-381. [PMID: 27719663 PMCID: PMC11345863 DOI: 10.2174/1570162x14666161006121455] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 08/23/2016] [Accepted: 08/23/2016] [Indexed: 11/22/2022]
Abstract
If we have any hope of achieving a cure for HIV infection, close attention to the cell types capable of getting infected with HIV is necessary. Of these cell types, astrocytes are the most ideal cell type for the formation of such a reservoir. These are long-lived cells with a very low turnover rate and are found in the brain and the gastrointestinal tract. Although astrocytes are evidently resistant to infection of cell-free HIV in vitro, these cells are efficiently infected via cell-tocell contact by which immature HIV virions bud off lymphocytes and have the ability to directly bind to CXCR4, triggering the process of fusion in the absence of CD4. In this review, we closely examine the evidence for HIV infection of astrocytes in the brain and the mechanisms for viral entry and regulation in this cell type, and discuss an approach for controlling this viral reservoir.
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Affiliation(s)
- Guan-Han Li
- Section of Infections of the Nervous System, NIH/NINDS, 10 Centre Dr., 7C120, Bethesda, MD 20814, USA.
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9
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Rai DK, Lawrence P, Kloc A, Schafer E, Rieder E. Analysis of the interaction between host factor Sam68 and viral elements during foot-and-mouth disease virus infections. Virol J 2015; 12:224. [PMID: 26695943 PMCID: PMC4689063 DOI: 10.1186/s12985-015-0452-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/10/2015] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The nuclear protein Src-associated protein of 68 kDa in mitosis (Sam68) is known to bind RNA and be involved in cellular processes triggered in response to environmental stresses, including virus infection. Interestingly, Sam68 is a multi-functional protein implicated in the life cycle of retroviruses and picornaviruses and is also considered a marker of virus-induced stress granules (SGs). Recently, we demonstrated the partial redistribution of Sam68 to the cytoplasm in FMDV infected cells, its interaction with viral protease 3C(pro), and found a significant reduction in viral titers as consequence of Sam68-specific siRNA knockdowns. Despite of that, details of how it benefits FMDV remains to be elucidated. METHODS Sam68 cytoplasmic localization was examined by immunofluorescent microscopy, counterstaining with antibodies against Sam68, a viral capsid protein and markers of SGs. The relevance of RAAA motifs in the IRES was investigated using electromobility shift assays with Sam68 protein and parental and mutant FMDV RNAs. In addition, full genome WT and mutant or G-luc replicon RNAs were tested following transfection in mammalian cells. The impact of Sam68 depletion to virus protein and RNA synthesis was investigated in a cell-free system. Lastly, through co-immunoprecipitation, structural modeling, and subcellular fractionation, viral protein interactions with Sam68 were explored. RESULTS FMDV-induced cytoplasmic redistribution of Sam68 resulted in it temporarily co-localizing with SG marker: TIA-1. Mutations that disrupted FMDV IRES RAAA motifs, with putative affinity to Sam68 in domain 3 and 4 cause a reduction on the formation of ribonucleoprotein complexes with this protein and resulted in non-viable progeny viruses and replication-impaired replicons. Furthermore, depletion of Sam68 in cell-free extracts greatly diminished FMDV RNA replication, which was restored by addition of recombinant Sam68. The results here demonstrated that Sam68 specifically co-precipitates with both FMDV 3D(pol) and 3C(pro) consistent with early observations of FMDV 3C(pro)-induced cleavage of Sam68. CONCLUSION We have found that Sam68 is a specific binding partner for FMDV non-structural proteins 3C(pro) and 3D(pol) and showed that mutations at RAAA motifs in IRES domains 3 and 4 cause a decrease in Sam68 affinity to these RNA elements and rendered the mutant RNA non-viable. Interestingly, in FMDV infected cells re-localized Sam68 was transiently detected along with SG markers in the cytoplasm. These results support the importance of Sam68 as a host factor co-opted by FMDV during infection and demonstrate that Sam68 interact with both, FMDV RNA motifs in the IRES and viral non-structural proteins 3C(pro) and 3D(pol).
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Affiliation(s)
- Devendra K Rai
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Paul Lawrence
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Anna Kloc
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Elizabeth Schafer
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
| | - Elizabeth Rieder
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, USDA/ARS/NAA, P.O. Box 848, Greenport, NY, 11944, USA.
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10
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Fan Y, Timani KA, He JJ. STAT3 and its phosphorylation are involved in HIV-1 Tat-induced transactivation of glial fibrillary acidic protein. Curr HIV Res 2015; 13:55-63. [PMID: 25613134 DOI: 10.2174/1570162x13666150121115804] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 12/17/2014] [Accepted: 01/14/2015] [Indexed: 01/31/2023]
Abstract
Human immunodeficiency virus type 1 (HIV-1) Tat protein is a major pathogenic factor in HIV-associated neurological diseases; it exhibits direct neurotoxicity and indirect astrocyte-mediated neurotoxicity. We have shown that Tat alone is capable of activating glial fibrillary acidic protein (GFAP) expression and inducing astrocytosis involving sequential activation of early growth response protein 1 (Egr-1) and p300. In this study, we determined the roles of signal transducer and activator of transcription 3 (STAT3) in Tat-induced GFAP transactivation. STAT3 expression and phosphorylation led to significant increases in GFAP transcription and protein expression. Tat expression was associated with increased STAT3 expression and phosphorylation in Tat-expressing astrocytes and HIV-infected astrocytes. GFAP, Egr-1 and p300 transcription and protein expression all showed positive response to STAT3 and its phosphorylation. Importantly, knockdown of STAT3 resulted in significant decreases in Tat-induced GFAP and Egr-1 transcription and protein expression. Taken together, these findings show that STAT3 is involved in and acts upstream of Egr1 and p300 in the Tat-induced GFAP transactivation cascade and suggest important roles of STAT3 in controlling astrocyte proliferation and activation in the HIV-infected central nervous system.
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Affiliation(s)
| | | | - Johnny J He
- Department of Cell Biology and Immunology, Graduate School of Biomedical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX 76107, USA.
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11
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Abstract
The requirement of HIV-1 and HTLV-1 to export incompletely spliced mRNAs has necessitated the evolution of Rev and Rex, respectively, to overcome host cellular mechanism that block nuclear-cytoplasmic export of incompletely processed mRNAs. Evaluating the function of these viral factors can be done at multiple levels: examining the functional consequence of Rev/Rex on viral gene expression, monitoring the movement of these proteins between the nucleus and cytoplasm or the subcellular distribution of the viral mRNAs. Here, I describe procedures to evaluate each of these aspects of Rev/Rex function.
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Affiliation(s)
- Alan Cochrane
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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12
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Gao G, Wu X, Zhou J, He M, He JJ, Guo D. Inhibition of HIV-1 transcription and replication by a newly identified cyclin T1 splice variant. J Biol Chem 2013; 288:14297-14309. [PMID: 23569210 DOI: 10.1074/jbc.m112.438465] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A variety of cellular factors participates in the HIV-1 life cycle. Among them is the well characterized cyclin T1 (CYCT1). CycT1 binds to cyclin-dependent kinase 9 (CDK9) and forms the positive transcription elongation factor-b (P-TEFb). P-TEFb is then recruited by HIV-1 TAT to the HIV-1 long terminal repeat (LTR) promoter and subsequently leads to phosphorylation of the C-terminal domain of RNA polymerase II (pol II), enhanced processivity of pol II, and transcription of a full-length HIV-1 RNA. In this study, we report the identification of a new CYCT1 splice variant, designated as CYCT1b, and accordingly we renamed CYCT1 as CYCT1a. CYCT1b was detected in several cell lines, including primary human CD4 T cells, and its expression was subject to cell cycle regulation. Similar to CYCT1a, CYCT1b was primarily localized in the nucleus. CYCT1b expression was found to be inversely correlated with HIV-1 gene expression and replication. This inverse correlation appeared to involve TAT transactivation, CDK9 binding, and subsequent recruitment of P-TEFb to the HIV-1 LTR promoter and pol II C-terminal domain phosphorylation. In agreement with these findings, CYCT1b expression led to direct inhibition of TAT-transactivated transcription of the HIV-1 LTR promoter. Taken together, these results show that the newly identified CYCT1b splice variant inhibits HIV-1 transcription and may provide new clues for the development of anti-HIV strategies.
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Affiliation(s)
- Guozhen Gao
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China; Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Xiaoyun Wu
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China
| | - Jieqiong Zhou
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China
| | - Mingfeng He
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Johnny J He
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202; Center for AIDS Research, Indiana University School of Medicine, Indianapolis, Indiana 46202; University of North Texas Health Science Center, Fort Worth, Texas 76107.
| | - Deyin Guo
- State Key Laboratory of Virology and Modern Virology Research Center, Wuhan University College of Life Sciences, 430072 Wuhan, China; Institute of Medical Virology, Wuhan University School of Medicine, 430071 Wuhan, China.
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13
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RNA-binding protein Sam68 controls synapse number and local β-actin mRNA metabolism in dendrites. Proc Natl Acad Sci U S A 2013; 110:3125-30. [PMID: 23382180 DOI: 10.1073/pnas.1209811110] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Proper synaptic function requires the spatial and temporal compartmentalization of RNA metabolism via transacting RNA-binding proteins (RBPs). Loss of RBP activity leads to abnormal posttranscriptional regulation and results in diverse neurological disorders with underlying deficits in synaptic morphology and transmission. Functional loss of the 68-kDa RBP Src associated in mitosis (Sam68) is associated with the pathogenesis of the neurological disorder fragile X tremor/ataxia syndrome. Sam68 binds to the mRNA of β-actin (actb), an integral cytoskeletal component of dendritic spines. We show that Sam68 knockdown or disruption of the binding between Sam68 and its actb mRNA cargo in primary hippocampal cultures decreases the amount of actb mRNA in the synaptodendritic compartment and results in fewer dendritic spines. Consistent with these observations, we find that Sam68-KO mice have reduced levels of actb mRNA associated with synaptic polysomes and diminished levels of synaptic actb protein, suggesting that Sam68 promotes the translation of actb mRNA at synapses in vivo. Moreover, genetic knockout of Sam68 or acute knockdown in vivo results in fewer excitatory synapses in the hippocampal formation as assessed morphologically and functionally. Therefore, we propose that Sam68 regulates synapse number in a cell-autonomous manner through control of postsynaptic actb mRNA metabolism. Our research identifies a role for Sam68 in synaptodendritic posttranscriptional regulation of actb and may provide insight into the pathophysiology of fragile X tremor/ataxia syndrome.
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14
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Hoffmann D, Schwarck D, Banning C, Brenner M, Mariyanna L, Krepstakies M, Schindler M, Millar DP, Hauber J. Formation of trans-activation competent HIV-1 Rev:RRE complexes requires the recruitment of multiple protein activation domains. PLoS One 2012; 7:e38305. [PMID: 22675540 PMCID: PMC3366918 DOI: 10.1371/journal.pone.0038305] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/07/2012] [Indexed: 12/13/2022] Open
Abstract
The HIV-1 Rev trans-activator is a nucleocytoplasmic shuttle protein that is essential for virus replication. Rev directly binds to unspliced and incompletely spliced viral RNA via the cis-acting Rev Response Element (RRE) sequence. Subsequently, Rev oligomerizes cooperatively and interacts with the cellular nuclear export receptor CRM1. In addition to mediating nuclear RNA export, Rev also affects the stability, translation and packaging of Rev-bound viral transcripts. Although it is established that Rev function requires the multimeric assembly of Rev molecules on the RRE, relatively little is known about how many Rev monomers are sufficient to form a trans-activation competent Rev:RRE complex, or which specific activity of Rev is affected by its oligomerization. We here analyzed by functional studies how homooligomer formation of Rev affects the trans-activation capacity of this essential HIV-1 regulatory protein. In a gain-of-function approach, we fused various heterologous dimerization domains to an otherwise oligomerization-defective Rev mutant and were able to demonstrate that oligomerization of Rev is not required per se for the nuclear export of this viral trans-activator. In contrast, however, the formation of Rev oligomers on the RRE is a precondition to trans-activation by directly affecting the nuclear export of Rev-regulated mRNA. Moreover, experimental evidence is provided showing that at least two protein activation domains are required for the formation of trans-activation competent Rev:RRE complexes. The presented data further refine the model of Rev trans-activation by directly demonstrating that Rev oligomerization on the RRE, thereby recruiting at least two protein activation domains, is required for nuclear export of unspliced and incompletely spliced viral RNA.
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Affiliation(s)
- Dirk Hoffmann
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Doreen Schwarck
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Carina Banning
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Matthias Brenner
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Lakshmikanth Mariyanna
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Marcel Krepstakies
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - Michael Schindler
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
| | - David P. Millar
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California, United States of America
| | - Joachim Hauber
- Heinrich Pette Institute – Leibniz Institute for Experimental Virology, Hamburg, Germany
- * E-mail:
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15
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Lawrence P, Schafer EA, Rieder E. The nuclear protein Sam68 is cleaved by the FMDV 3C protease redistributing Sam68 to the cytoplasm during FMDV infection of host cells. Virology 2012; 425:40-52. [PMID: 22280896 DOI: 10.1016/j.virol.2011.12.019] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 11/23/2011] [Accepted: 12/31/2011] [Indexed: 01/28/2023]
Abstract
Picornavirus infection can lead to disruption of nuclear pore traffic, shut-off of cell translation machinery, and cleavage of proteins involved in cellular signal transduction and the innate response to infection. Here, we demonstrated that the FMDV 3C(pro) induced the cleavage of nuclear RNA-binding protein Sam68 C-terminus containing the nuclear localization sequence (NLS). Consequently, it stimulated the redistribution of Sam68 to the cytoplasm. The siRNA knockdown of Sam68 resulted in a 1000-fold reduction in viral titers, which prompted us to study the effect of Sam68 on FMDV post-entry events. Interestingly, Sam68 interacts with the internal ribosomal entry site within the 5' non-translated region of the FMDV genome, and Sam68 knockdown decreased FMDV IRES-driven activity in vitro suggesting that it could modulate translation of the viral genome. The results uncover a novel role for Sam68 in the context of picornaviruses and the proteolysis of a new cellular target of the FMDV 3C(pro).
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Affiliation(s)
- Paul Lawrence
- Foreign Animal Disease Research Unit, United States Department of Agriculture, Agricultural Research Service, Plum Island Animal Disease Center, Greenport, NY 11944, USA
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16
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Liu J, Henao-Mejia J, Liu H, Zhao Y, He JJ. Translational regulation of HIV-1 replication by HIV-1 Rev cellular cofactors Sam68, eIF5A, hRIP, and DDX3. J Neuroimmune Pharmacol 2011; 6:308-21. [PMID: 21360055 DOI: 10.1007/s11481-011-9265-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 02/14/2011] [Indexed: 10/18/2022]
Abstract
Nuclear export and translation of HIV-1 RNA are two important posttranscriptional events for HIV-1 gene expression and replication. HIV-1 Rev functions to export unspliced and incompletely spliced HIV-1 RNA from the nucleus to the cytoplasm; it requires interaction with several cellular cofactors such as Sam68, eIF5A, hRIP, and DDX3. Meanwhile, some studies have also implicated Rev and some of its cofactors such as Sam68 in HIV-1 RNA translation. Thus, in this study, we aimed to characterize the potential function of all these four Rev cofactors in HIV-1 RNA translation. Ectopic expression, siRNA knockdown, and trans-complementation assays confirmed that all these cofactors were very important for HIV-1 gene expression and production through Rev and, accordingly, Rev-dependent reporter gene expression. Importantly, these studies revealed for the first time that each of these cofactors also regulated Rev-independent reporter gene expression. To directly determine the roles of these cofactors in HIV-1 RNA translation, we designed and synthesized a full-length capped HIV-1 RNA in vitro, transfected it into cells to bypass the RNA nuclear export step, and determined HIV-1 Gag expression from the cytoplasmic RNA in the cells that had ectopically expressed or siRNA knocked down cofactors. Gag expression was found to closely correlate with the expression levels of all these cofactors. Furthermore, we took advantage of a HIV-1 internal ribosomal entry site (IRES)-based bicistronic reporter gene assay and determined the effects of these cofactors on cap-independent IRES-mediated HIV-1 translation. The results showed that DDX3, eIF5A, and hRIP enhanced HIV-1 IRES-mediated translation, whereas Sam68 did not. Taken together, these results show that HIV-1 Rev cofactors Sam68, eIF5A, hRIP, and DDX3 also function in the translation of HIV-1 RNA and suggest that the regulatory mechanisms of HIV-1 RNA translation are likely different among these cofactors.
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Affiliation(s)
- Jinfeng Liu
- The First Affiliated Hospital, Xi'an Jiaotong University College of Medicine, Xi'an, Shaanxi 710061, People's Republic of China
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17
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Control of HIV replication in astrocytes by a family of highly conserved host proteins with a common Rev-interacting domain (Risp). AIDS 2010; 24:2433-42. [PMID: 20827171 DOI: 10.1097/qad.0b013e32833e8758] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE In human astrocytes, restriction of HIV replication involves inhibition of HIV Rev activity. We previously identified a Rev-interacting human protein fragment (16.4.1) that can reduce Rev activity. The 16.4.1 sequence is contained in a group of highly similar host cell proteins, which we call the Risp family. Here we investigate whether the Risp family is connected to HIV replication in astrocytes. METHODS Cell/tissue lysates were analyzed for Risp expression by western blot with various anti-Risp antibodies. The interaction of astrocytic Risp members with Rev was investigated by affinity chromatography. Astrocytes were transfected with expression plasmids containing cDNAs encoding full-length Risp or the isolated 16.4.1 region for Risp overexpression or with siRNAs designed for Risp knock-down. Rev activity was investigated with a Rev-reporter assay. RNA levels were quantified by real-time RT-PCR, HIV Gag levels by p24ELISA. RESULTS Expression of the Risp family was demonstrated in human brain tissues and astrocytes. Astrocytes were shown to produce Risp family members that interact with Rev. Production of HIV Gag proteins and Rev-dependent RNAs in persistently infected astrocytes increased upon Risp knock-down and decreased upon Risp overexpression. Risp knock-down increased Rev activity and raised proportions of Rev proteins in the nucleus of astrocytes. CONCLUSION Our results link the Risp family to restriction of HIV production and inhibition of Rev activity in astrocytes. We conclude that the Risp family represents a novel family of host factors that can control HIV replication and may be important for the containment of HIV infection in brain reservoirs.
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18
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Sette C. Post-translational regulation of star proteins and effects on their biological functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 693:54-66. [PMID: 21189685 DOI: 10.1007/978-1-4419-7005-3_4] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
STAR (Signal Transduction and Activation of RNA) proteins owed their name to the presence in their structure ofa RNA-binding domain and several hallmarks of their involvement in signal transduction pathways. In many members of the family, the STAR RNA-binding domain (also named GSG, an acronym for GRP33/Sam68/ GLD-1) is flanked by regulatory regions containing proline-rich sequences, which serve as docking sites for proteins containing SH3 and WW domains and also a tyrosine-rich region at the C-terminus, which can mediateprotein-protein interactions with partners through SH2 domains. These regulatory regions contain consensus sequences for additional modifications, including serine/threonine phosphorylation, methylation, acetylation and sumoylation. Since their initial description, evidence has been gathered in different cell types and model organisms that STAR proteins can indeed integrate signals from external and internal cues with changes in transcription and processing of target RNAs. The most striking example of the high versatility of STAR proteins is provided by Sam68 (KHDRBS1), whose function, subcellular localization and affinity for RNA are strongly modulated by several signaling pathways through specific modifications. Moreover, the recent development of genetic knockout models has unveiled the physiological function of some STAR proteins, pointing to a crucial role of their post-translational modifications in the biological processes regulated by these RNA-binding proteins. This chapter offers an overview of the most updated literature on the regulation of STAR proteins by post-translational modifications and illustrates examples of how signal transduction pathways can modulate their activity and affect biological processes.
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Affiliation(s)
- Claudio Sette
- Department of Public Health and Cell Biology, University of Rome Tor Vergata, Via Montpellier, 1, 00133, Rome, Italy.
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19
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Huot ME, Vogel G, Richard S. Identification of a Sam68 ribonucleoprotein complex regulated by epidermal growth factor. J Biol Chem 2009; 284:31903-13. [PMID: 19762470 DOI: 10.1074/jbc.m109.018465] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Sam68, Src associated in mitosis of 68 kDa, is a known RNA-binding protein and a signaling adaptor protein for tyrosine kinases. However, the proteins associated with Sam68 and the existence of a Sam68 complex, its mass, and regulation are, however, unknown. Herein we identify a large Sam68 complex with a mass >1 MDa in HeLa cells that is composed of approximately 40 proteins using an immunoprecipitation followed by a mass spectrometry approach. Many of the proteins identified are RNA-binding proteins and are known components of a previously identified structure termed the spreading initiation center. The large Sam68 complex is a ribonucleoprotein complex, as treatment with RNases caused a shift in the molecular mass of the complex to 200-450 kDa. Moreover, treatment of HeLa cells with phorbol 12-myristate 13-acetate or epidermal growth factor induced the disassociation of Sam68 from the large complex and the appearance of Sam68 within the smaller complex. Actually, in certain cell lines such as breast cancer cell lines MCF-7 and BT-20, Sam68 exists in equilibrium between a large and a small complex. The appearance of the small Sam68 complex in cells correlates with the ability of Sam68 to promote the alternative splicing of CD44 and cell migration. Our findings show that Sam68 exists in equilibrium in transformed cells between two complexes and that extracellular signals, such as epidermal growth factor stimulation, promote alternative splicing by modulating the composition of the Sam68 complex.
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Affiliation(s)
- Marc-Etienne Huot
- Terry Fox Molecular Oncology Group and the Bloomfield Center for Research on Aging, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Montréal, Québec H3T 1E2, Canada
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Zhou Y, Rong L, Zhang J, Aloysius C, Pan Q, Liang C. Insulin-like growth factor II mRNA binding protein 1 modulates Rev-dependent human immunodeficiency virus type 1 RNA expression. Virology 2009; 393:210-20. [PMID: 19726068 DOI: 10.1016/j.virol.2009.08.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2009] [Revised: 06/02/2009] [Accepted: 08/04/2009] [Indexed: 01/07/2023]
Abstract
Human immunodeficiency virus type 1 (HIV-1) needs to overcome cellular counter mechanisms such as to successfully propagate itself. Results of our recent studies show that overexpression of insulin-like growth factor II mRNA binding protein 1 (IMP1) inhibits production of infectious HIV-1 particles through adversely affecting virus maturation. Here, we report that IMP1 interacts with HIV-1 Rev protein and its ectopic expression causes relocation of Rev from the nucleus to the cytoplasm. In accordance with this observation, ectopic expression of IMP1 severely diminishes Rev-dependent expression of CAT enzyme and disturbs HIV-1 RNA expression by causing accumulation of the multiple spliced viral RNA. Results of mutagenesis analysis further reveal that the KH4 domain represents the key element of IMP1 in modulating HIV-1 RNA expression. Taken together, these data suggest, in addition to hampering virus assembly, that IMP1 also has an effect on Rev-dependent viral RNA expression.
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Affiliation(s)
- Yongdong Zhou
- McGill AIDS Centre, Lady Davis Institute-Jewish General Hospital, Montreal, Quebec, Canada H3T 1E2
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21
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He JJ, Henao-Mejia J, Liu Y. Sam68 functions in nuclear export and translation of HIV-1 RNA. RNA Biol 2009; 6:384-6. [PMID: 19535902 DOI: 10.4161/rna.6.4.8920] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Productive HIV-1 replication is mainly controlled at the transcriptional level by HIV-1 Tat and at the post-transcriptional level by HIV-1 Rev. A number of host factors have been identified to be involved in these processes. Src-associated protein of 68 kDa in mitosis (Sam68) is a multi-functional RNA-binding protein and has been implicated in several important cellular processes. More evidence has accumulated to support an important regulatory function of Sam68 at two distinct steps of HIV-1 gene expression. Sam68 interacts with HIV-1 Rev protein and directly participates in nuclear exportation of HIV-1 unspliced or singly spliced RNA. In addition, Sam68 functions in the cytoplasmic processes of HIV-1 replication such as the translational regulation of HIV-1 RNA. Elucidation of the precise molecular function of Sam68 in HIV-1 gene expression is clearly warranted and is expected to unambiguously establish Sam68 as an important host factor for HIV-1 replication.
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Affiliation(s)
- Johnny J He
- Center for AIDS Research and Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
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22
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Park IW, Han C, Song X, Green LA, Wang T, Liu Y, Cen C, Song X, Yang B, Chen G, He JJ. Inhibition of HIV-1 entry by extracts derived from traditional Chinese medicinal herbal plants. Altern Ther Health Med 2009; 9:29. [PMID: 19656383 PMCID: PMC2736925 DOI: 10.1186/1472-6882-9-29] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Accepted: 08/05/2009] [Indexed: 01/10/2023]
Abstract
Background Highly active anti-retroviral therapy (HAART) is the current HIV/AIDS treatment modality. Despite the fact that HAART is very effective in suppressing HIV-1 replication and reducing the mortality of HIV/AIDS patients, it has become increasingly clear that HAART does not offer an ultimate cure to HIV/AIDS. The high cost of the HAART regimen has impeded its delivery to over 90% of the HIV/AIDS population in the world. This reality has urgently called for the need to develop inexpensive alternative anti-HIV/AIDS therapy. This need has further manifested by recent clinical trial failures in anti-HIV-1 vaccines and microbicides. In the current study, we characterized a panel of extracts of traditional Chinese medicinal herbal plants for their activities against HIV-1 replication. Methods Crude and fractionated extracts were prepared from various parts of nine traditional Chinese medicinal herbal plants in Hainan Island, China. These extracts were first screened for their anti-HIV activity and cytotoxicity in human CD4+ Jurkat cells. Then, a single-round pseudotyped HIV-luciferase reporter virus system (HIV-Luc) was used to identify potential anti-HIV mechanisms of these extracts. Results Two extracts, one from Euphorbiaceae, Trigonostema xyphophylloides (TXE) and one from Dipterocarpaceae, Vatica astrotricha (VAD) inhibited HIV-1 replication and syncytia formation in CD4+ Jurkat cells, and had little adverse effects on host cell proliferation and survival. TXE and VAD did not show any direct inhibitory effects on the HIV-1 RT enzymatic activity. Treatment of these two extracts during the infection significantly blocked infection of the reporter virus. However, pre-treatment of the reporter virus with the extracts and treatment of the extracts post-infection had little effects on the infectivity or gene expression of the reporter virus. Conclusion These results demonstrate that TXE and VAD inhibit HIV-1 replication likely by blocking HIV-1 interaction with target cells, i.e., the interaction between gp120 and CD4/CCR5 or gp120 and CD4/CXCR4 and point to the potential of developing these two extracts to be HIV-1 entry inhibitors.
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Casafont I, Berciano MT, Lafarga M. Bortezomib induces the formation of nuclear poly(A) RNA granules enriched in Sam68 and PABPN1 in sensory ganglia neurons. Neurotox Res 2009; 17:167-78. [PMID: 19609631 DOI: 10.1007/s12640-009-9086-1] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 06/17/2009] [Accepted: 06/24/2009] [Indexed: 11/28/2022]
Abstract
The ubiquitin-dependent proteasome system (UPS) is the major pathway responsible for selective nuclear and cytoplasmic protein degradation. Bortezomib, a boronic acid dipeptide, is a reversible 20S proteasome inhibitor used as novel anticancer drug, particularly in the treatment of multiple myeloma and certain lymphomas. Bortezomib-induced peripheral neuropathy (BIPN) is a widely recognized dose-limiting neurotoxicity of this proteasome inhibitor, which causes a significant negative impact on the quality of life. The pathogenic mechanisms underlying bortezomib neurotoxicity are little known. In this study a rat was used as our animal model to investigate the bortezomib-induced nuclear changes in dorsal root ganglia (DRG) neurons. Our results indicate that this neuronal population is an important target of bortezomib neurotoxicity. Nuclear changes include accumulation of ubiquitin-protein conjugates, reduction of transcriptional activity, and nuclear retention of poly(A) RNAs in numerous spherical or ring-shaped dense granules. They also contained the RNA-binding proteins PABPN1 (poly(A) binding protein nuclear 1) and Sam68, but lacked the mRNA nuclear export factors REF and Y14. At the cytoplasmic level, most neurons exhibited chromatolysis, supporting the inhibition of mRNA translation. Our results indicate that bortezomib interferes with transcription, nuclear processing and transport, and cytoplasmic translation of mRNAs in DRG neurons. They also support that this neuronal dysfunction is an essential pathogenic mechanism in the BIPN, which is characterized by sensory impairment including sensory ataxia.
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Affiliation(s)
- Iñigo Casafont
- Department of Anatomy and Cell Biology and Centro de Investigación Biomédica en Red sobre Enferemedades Neurodegenerativas (CIBERNED), Faculty of Medicine, University of Cantabria, Avd. Cardenal Herrera Oria s/n, Santander, Spain
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24
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Henao-Mejia J, He JJ. Sam68 relocalization into stress granules in response to oxidative stress through complexing with TIA-1. Exp Cell Res 2009; 315:3381-95. [PMID: 19615357 DOI: 10.1016/j.yexcr.2009.07.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 06/21/2009] [Accepted: 07/08/2009] [Indexed: 12/25/2022]
Abstract
Sam68 has been implicated in a variety of important cellular processes such as RNA metabolism and intracellular signaling. We have recently shown that Sam68 cytoplasmic mutants induce stress granules (SG) and inhibit HIV-1 nef mRNA translation [J. Henao-Mejia, Y. Liu, I.W. Park, J. Zhang, J. Sanford, J.J. He, Suppression of HIV-1 Nef translation by Sam68 mutant-induced stress granules and nef mRNA sequestration, Mol. Cell 33 (2009) 87-96]. These findings prompted us to investigate the possibility and the underlying mechanisms of the wild-type counterpart Sam68 SG recruitment. Herein, we revealed that Sam68 was significantly recruited into cytoplasmic SG under oxidative stress. We then demonstrated that domain aa269-321 and KH domain were both essential for this recruitment. Nevertheless, Sam68 knockdown had no effects on SG assembly, indicating that Sam68 is not a constitutive component of the SG. Moreover, we showed that Sam68 cytoplasmic mutant-induced SG formation was independent of eIF2alpha phosphorylation. Lastly, we demonstrated that Sam68 was complexed with T-cell intracellular antigen-1 (TIA-1), a core SG component, and that the complex formation was correlated with Sam68 SG recruitment. Taken together, these results provide direct evidence for the first time that Sam68 is recruited into SG through complexing with TIA-1 in response to oxidative stress and suggest that cytoplasmic SG recruitment of Sam68 and ensuing changes in Sam68 physiological functions are part of the host response to external stressful conditions.
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Affiliation(s)
- Jorge Henao-Mejia
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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25
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Paronetto MP, Messina V, Bianchi E, Barchi M, Vogel G, Moretti C, Palombi F, Stefanini M, Geremia R, Richard S, Sette C. Sam68 regulates translation of target mRNAs in male germ cells, necessary for mouse spermatogenesis. ACTA ACUST UNITED AC 2009; 185:235-49. [PMID: 19380878 PMCID: PMC2700383 DOI: 10.1083/jcb.200811138] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Sam68 is a KH-type RNA-binding protein involved in several steps of RNA metabolism with potential implications in cell differentiation and cancer. However, its physiological roles are still poorly understood. Herein, we show that Sam68(-/-) male mice are infertile and display several defects in spermatogenesis, demonstrating an essential role for Sam68 in male fertility. Sam68(-/-) mice produce few spermatozoa, which display dramatic motility defects and are unable to fertilize eggs. Expression of a subset of messenger mRNAs (mRNAs) is affected in the testis of knockout mice. Interestingly, Sam68 is associated with polyadenylated mRNAs in the cytoplasm during the meiotic divisions and in round spermatids, when it interacts with the translational machinery. We show that Sam68 is required for polysomal recruitment of specific mRNAs and for accumulation of the corresponding proteins in germ cells and in a heterologous system. These observations demonstrate a novel role for Sam68 in mRNA translation and highlight its essential requirement for the development of a functional male gamete.
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Affiliation(s)
- Maria Paola Paronetto
- Department of Public Health and Cell Biology, Section of Anatomy, University of Rome Tor Vergata, 00133 Rome, Italy
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26
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Abstract
Rev remains a hot topic. In this review, we revisit the insights that have been gained into the control of gene expression by the retroviral protein Rev and speculate on where current research is leading. We outline what is known about the role of Rev in translation and encapsidation and how these are linked to its more traditional role of nuclear export, underlining the multifaceted nature of this small viral protein. We discuss what more is to be learned in these fields and why continuing research on these 116 amino acids and understanding their function is still important in devising methods to combat AIDS.
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Affiliation(s)
- H C T Groom
- Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK
| | - E C Anderson
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - A M L Lever
- Department of Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK
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27
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28
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Henao-Mejia J, Liu Y, Park IW, Zhang J, Sanford J, He JJ. Suppression of HIV-1 Nef translation by Sam68 mutant-induced stress granules and nef mRNA sequestration. Mol Cell 2009; 33:87-96. [PMID: 19150430 DOI: 10.1016/j.molcel.2008.11.024] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 09/21/2008] [Accepted: 11/01/2008] [Indexed: 02/01/2023]
Abstract
HIV-1 Nef plays important roles in HIV-1 replication and pathogenesis. It is translated from completely spliced HIV-1 RNA, and its expression is inherently regulated at the levels of viral DNA transcription and RNA splicing. Here we show that Sam68 cytoplasmic mutants potently suppress Nef expression. The suppression requires Sam68 domain aa 269-321 and is correlated with its ability to induce stress granules. In addition, the suppression is specific to Nef, and direct binding to nef mRNA 3'UTR confers the suppression specificity. Furthermore, nef mRNA is targeted to and enriched in these induced stress granules. Importantly, Nef suppression occurs in the context of HIV-1 infection of CD4+ T lymphocytes with little MHC I and CD4 downregulation. Taken together, these results demonstrate that stress granule induction and nef mRNA sequestration account for this translational suppression of Nef expression and offer a strategy for development of anti-HIV therapeutics to buttress our fight against HIV/AIDS.
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Affiliation(s)
- Jorge Henao-Mejia
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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29
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An adaptor role for cytoplasmic Sam68 in modulating Src activity during cell polarization. Mol Cell Biol 2009; 29:1933-43. [PMID: 19139276 DOI: 10.1128/mcb.01707-08] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The Src-associated substrate during mitosis with a molecular mass of 68 kDa (Sam68) is predominantly nuclear and is known to associate with proteins containing the Src homology 3 (SH3) and SH2 domains. Although Sam68 is a Src substrate, little is known about the signaling pathway that link them. Src is known to be activated transiently after cell spreading, where it modulates the activity of small Rho GTPases. Herein we report that Sam68-deficient cells exhibit loss of cell polarity and cell migration. Interestingly, Sam68-deficient cells exhibited sustained Src activity after cell attachment, resulting in the constitutive tyrosine phosphorylation and activation of p190RhoGAP and its association with p120rasGAP. Consistently, we observed that Sam68-deficient cells exhibited deregulated RhoA and Rac1 activity. By using total internal reflection fluorescence microscopy, we observed Sam68 near the plasma membrane after cell attachment coinciding with phosphorylation of its C-terminal tyrosines and association with Csk. These findings show that Sam68 localizes near the plasma membrane during cell attachment and serves as an adaptor protein to modulate Src activity for proper signaling to small Rho GTPases.
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30
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McLaren M, Cochrane A. Mapping of determinants involved in the stimulation of HIV-1 expression by Sam68. Virology 2008; 385:93-104. [PMID: 19091369 DOI: 10.1016/j.virol.2008.10.049] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2008] [Revised: 08/15/2008] [Accepted: 10/27/2008] [Indexed: 10/21/2022]
Abstract
Control of HIV-1 RNA processing is central to the replication of the virus. Previously, we demonstrated that the cellular protein Sam68 enhances HIV-1 structural protein expression and RNA 3' end processing. In this report, we show that Sam68 interacts with unspliced HIV-1 RNA and that other members of the STAR/GSG protein family also promote viral RNA 3' end processing. We define a portion of the GSG domain (Sam 97-255) as sufficient for enhancement of Rev-dependent expression. In contrast to Sam68, Sam 97-255 increases unspliced RNA processing only in the presence of Rev in 293T cells. In a different cell line, Sam 97-255 enhances HIV-1 gene expression without enhancing RNA 3' end processing, suggesting that stimulation of 3' end processing is not required for enhancement of HIV-1 gene expression. Overall, these results indicate that Sam68 and the mutants described affect the composition of the viral RNP to enhance viral protein synthesis.
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Affiliation(s)
- Meredith McLaren
- Department of Molecular Genetics, University of Toronto, Ontario, Canada
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31
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Marsh K, Soros V, Cochrane A. Selective translational repression of HIV-1 RNA by Sam68DeltaC occurs by altering PABP1 binding to unspliced viral RNA. Retrovirology 2008; 5:97. [PMID: 18957126 PMCID: PMC2584037 DOI: 10.1186/1742-4690-5-97] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Accepted: 10/28/2008] [Indexed: 12/13/2022] Open
Abstract
HIV-1 structural proteins are translated from incompletely spliced 9 kb and 4 kb mRNAs, which are transported to the cytoplasm by Crm1. It has been assumed that once in the cytoplasm, translation of incompletely spliced HIV-1 mRNAs occurs in the same manner as host mRNAs. Previous analyses have demonstrated that Sam68 and a mutant thereof, Sam68DeltaC, have dramatic effects on HIV gene expression, strongly enhancing and inhibiting viral structural protein synthesis, respectively. While investigating the inhibition of incompletely spliced HIV-1 mRNAs by Sam68DeltaC, we determined that the effect was independent of the perinuclear bundling of the viral RNA. Inhibition was dependent upon the nuclear export pathway used, as translation of viral RNA exported via the Tap/CTE export pathway was not blocked by Sam68DeltaC. We demonstrate that inhibition of HIV expression by Sam68DeltaC is correlated with a loss of PABP1 binding with no attendant change in polyadenosine tail length of the affected RNAs. The capacity of Sam68DeltaC to selectively inhibit translation of HIV-1 RNAs exported by Crm1 suggests that it is able to recognize unique characteristics of these viral RNPs, a property that could lead to new therapeutic approaches to controlling HIV-1 replication.
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Affiliation(s)
- Kim Marsh
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada.
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32
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Paronetto MP, Bianchi E, Geremia R, Sette C. Dynamic expression of the RNA-binding protein Sam68 during mouse pre-implantation development. Gene Expr Patterns 2008; 8:311-22. [PMID: 18321792 DOI: 10.1016/j.gep.2008.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 01/25/2008] [Indexed: 12/23/2022]
Abstract
The STAR protein Sam68 (KHDRBS1) is involved in several aspects of post-transcriptional mRNA metabolism. Herein, we have investigated the expression and subcellular localization of Sam68 during early mouse embryogenesis. We found that mouse oocytes express high levels of Sam68 mRNA, low levels of the transcript for Khdrbs2 (current symbol for Slm-1) and no Khdrbs3 (current symbol for Slm-2), two highly homologous STAR genes. Sam68 protein is expressed throughout oocyte meiotic maturation and early embryogenesis. It is released in the cytoplasm upon meiotic resumption and it slowly accumulates in the nucleus after fertilization. Unlike what was observed for other RNA-binding proteins, nuclear accumulation of Sam68 was independent of de novo mRNA transcription. However, we found that inhibition of mRNA translation by either cycloheximide or puromycin in one-cell embryos caused the accumulation of Sam68 in cytoplasmic granules. Analysis of these granules by deconvolution microscopy demonstrated that they are sites of accumulation for proteins involved in the initiation of mRNA translation, such as eIF4A1, eIF4E and eIF4G. These granules contained RNA and were dissolved by treatment with RNase A. Other proteins expressed by the zygote, like the splicing factor SC35 or the cytoplasmic kinase ERK2, did not accumulate in such structures after treatment with inhibitors of mRNA translation, indicating that the localization of Sam68 and of the translation initiation factors in these granules is a specific event. These results indicate that Sam68 is involved in translational regulation of maternal mRNAs in the zygote and in the early signaling events triggered by fertilization.
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Affiliation(s)
- Maria Paola Paronetto
- Department of Public Health and Cell Biology, Section of Anatomy, University of Rome Tor Vergata, Via Montpellier 1, 00133 Rome, Italy
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33
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Zhang J, Wu YO, Xiao L, Li K, Chen LL, Sirois P. Therapeutic potential of RNA interference against cellular targets of HIV infection. Mol Biotechnol 2007; 37:225-36. [PMID: 17952669 PMCID: PMC7091338 DOI: 10.1007/s12033-007-9000-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2007] [Accepted: 08/09/2007] [Indexed: 12/11/2022]
Abstract
RNA interference is not only very promising in identifying new targets for drug development, siRNA/shRNA themselves may be directly used as therapeutic agents. In inhibiting viral infections by RNA interference, both viral targets and cellular proteins have been evaluated. Most of the early studies in this field had chosen viral targets for RNA interference. However, recent efforts are mainly focusing on cellular proteins for RNA silencing due to the realization that a variety of viral responses substantially minimize siRNA effects. With the application of siRNA approaching, many new cellular targets relevant to HIV infection have been identified. The value of siRNA/shRNA in the treatment of AIDS is largely dependent on better understanding of the biology of HIV replication. Efforts in the identification of cellular processes with the employment of siRNA/shRNA have shed some new lights on our understanding of how HIV infection occurs. Furthermore, the relative specific effects and simplicity of design makes siRNA/shRNA themselves to be favorable drug leads.
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Affiliation(s)
- Jia Zhang
- Gene Core, The Genomics Institute of the Novartis Research Foundation, San Diego, CA, USA
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34
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Carroll-Anzinger D, Kumar A, Adarichev V, Kashanchi F, Al-Harthi L. Human immunodeficiency virus-restricted replication in astrocytes and the ability of gamma interferon to modulate this restriction are regulated by a downstream effector of the Wnt signaling pathway. J Virol 2007; 81:5864-71. [PMID: 17392368 PMCID: PMC1900315 DOI: 10.1128/jvi.02234-06] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Astrocyte dysregulation correlates with the severity and the rate of human immunodeficiency virus (HIV)-associated dementia (HAD) progression, highlighting a pivotal role for astrocytes in HIV neuropathogenesis. Yet, astrocytes limit HIV, indicating that they possess an intrinsic molecular mechanism to restrict HIV replication. We previously established that this restriction can be partly overcome by priming astrocytes with gamma interferon (IFN-gamma), which is elevated in the cerebral spinal fluid of HAD patients. We evaluated the mechanism of restrictive HIV replication in astrocytes and how IFN-gamma priming modulates this restriction. We demonstrate that the downstream effector of Wnt signaling, T-cell factor 4 (TCF-4), is part of a transcriptional complex that is immunoprecipitated with HIV TAR-containing region in untreated astrocytes but not in IFN-gamma-treated cells. Blocking TCF-4 activity with a dominant-negative mutant enhanced HIV replication by threefold in both the astrocytoma cell line U87MG and primary fetal astrocytes. Using a TCF-4 reporter plasmid, we directly demonstrate that Wnt signaling is active in human astrocytes and is markedly reduced by IFN-gamma treatment. Collectively, these data implicate TCF-4 in repressing HIV replication and the ability of IFN-gamma to regulate this restriction by inhibiting TCF-4. Given that TCF-4 is the downstream effector of Wnt signaling, harnessing Wnt signaling as an intrinsic molecular mechanism to limit HIV replication may emerge as a powerful tool to regulate HIV replication within and outside of the brain.
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Affiliation(s)
- Deborah Carroll-Anzinger
- Department of Immunology/Microbiology, Rush University Medical Center, 1735 W. Harrison Street, 614 Cohn, Chicago, IL 60612, USA
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35
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Felber BK, Zolotukhin AS, Pavlakis GN. Posttranscriptional Control of HIV‐1 and Other Retroviruses and Its Practical Applications. ADVANCES IN PHARMACOLOGY 2007; 55:161-97. [PMID: 17586315 DOI: 10.1016/s1054-3589(07)55005-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Barbara K Felber
- Human Retrovirus Pathogenesis Section, Vaccine Branch, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702, USA
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36
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Effect of proline rich domain of an RNA-binding protein Sam68 in cell growth process, death and B cell signal transduction. Chin Med J (Engl) 2006. [DOI: 10.1097/00029330-200609020-00006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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37
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Graf M, Ludwig C, Kehlenbeck S, Jungert K, Wagner R. A quasi-lentiviral green fluorescent protein reporter exhibits nuclear export features of late human immunodeficiency virus type 1 transcripts. Virology 2006; 352:295-305. [PMID: 16777165 DOI: 10.1016/j.virol.2006.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2005] [Revised: 02/23/2006] [Accepted: 05/02/2006] [Indexed: 10/24/2022]
Abstract
We have previously shown that Rev-dependent expression of HIV-1 Gag from CMV immediate early promoter critically depends on the AU-rich codon bias of the gag gene. Here, we demonstrate that adaptation of the green fluorescent protein (GFP) reporter gene to HIV codon bias is sufficient to turn this hivGFP RNA into a quasi-lentiviral message following the rules of late lentiviral gene expression. Accordingly, GFP expression was significantly decreased in transfected cells strictly correlating with reduced RNA levels. In the presence of the HIV 5' major splice donor, the hivGFP RNAs were stabilized in the nucleus and efficiently exported to the cytoplasm following fusion of the 3' Rev-responsive element (RRE) and coexpression of HIV-1 Rev. This Rev-dependent translocation was specifically inhibited by leptomycin B suggesting export via the CRM1-dependent pathway used by late lentiviral transcripts. In conclusion, this quasi-lentiviral reporter system may provide a new platform for developing sensitive Rev screening assays.
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Affiliation(s)
- Marcus Graf
- Institute of Medical Microbiology and Hygiene, Molecular Microbiology and Gene Therapy, University of Regensburg, 93053 Regensburg, Germany
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38
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Dangerfield JA, Hohenadl C, Egerbacher M, Kodajova P, Salmons B, Günzburg WH. HIV-1 Rev can specifically interact with MMTV RNA and upregulate gene expression. Gene 2005; 358:17-30. [PMID: 16023306 DOI: 10.1016/j.gene.2005.05.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2005] [Revised: 04/26/2005] [Accepted: 05/10/2005] [Indexed: 10/25/2022]
Abstract
We present evidence that the HIV-1 Rev protein can heterologously regulate expression of the simple beta retrovirus mouse mammary tumour virus (MMTV). Up to 10-fold upregulation was seen in a functional assay system when specific MMTV sequences were substituted for the HIV-1 Rev responsive element (RRE). RNA gel shift analysis showed that purified recombinant Rev could specifically bind to MMTV unique region 3 prime (U3) RNA and that these sequences could compete for wild-type Rev-RRE binding approximately 20-fold more efficiently than a non-specific competitor RNA. Using a combination of in silico and deletion mutation analyses, it was not possible to define any single specific secondary structure responsive to Rev, suggesting that a structure or combination of structures that only form in the context of the complete U3 transcript is/are required to interact with Rev. Taken together, these results suggest that HIV-1 Rev can directly bind to MMTV RNA as well as mediate upregulation of MMTV gene expression.
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Affiliation(s)
- John A Dangerfield
- Research Institute of Virology and Biomedicine, University of Veterinary Medicine, Vienna, Austria.
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39
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Li L, Li HS, Pauza CD, Bukrinsky M, Zhao RY. Roles of HIV-1 auxiliary proteins in viral pathogenesis and host-pathogen interactions. Cell Res 2005; 15:923-34. [PMID: 16354571 DOI: 10.1038/sj.cr.7290370] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Active host-pathogen interactions take place during infection of human immunodeficiency virus type 1 (HIV-1). Outcomes of these interactions determine the efficiency of viral infection and subsequent disease progression. HIV-infected cells respond to viral invasion with various defensive strategies such as innate, cellular and humoral immune antiviral mechanisms. On the other hand, the virus has also developed various offensive tactics to suppress these host cellular responses. Among many of the viral offensive strategies, HIV-1 viral auxiliary proteins (Tat, Rev, Nef, Vif, Vpr and Vpu) play important roles in the host-pathogen interaction and thus have significant impacts on the outcome of HIV infection. One of the best examples is the interaction of Vif with a host cytidine deaminase APOBEC3G. Although specific roles of other auxiliary proteins are not as well described as Vif-APOBEC3G interaction, it is the goal of this brief review to summarize some of the preliminary findings with the hope to stimulate further discussion and investigation in this exhilarating area of research.
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Affiliation(s)
- Lin Li
- Department of Pathology, Institute of Human Virology,University of Maryland, Baltimore, MD 21201, USA
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40
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Zhang J, Liu Y, Henao J, Rugeles MT, Li J, Chen T, He JJ. Requirement of an additional Sam68 domain for inhibition of human immunodeficiency virus type 1 replication by Sam68 dominant negative mutants lacking the nuclear localization signal. Gene 2005; 363:67-76. [PMID: 16236470 DOI: 10.1016/j.gene.2005.06.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Accepted: 06/29/2005] [Indexed: 11/29/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) replication requires active nuclear export of unspliced and incompletely spliced HIV-1 RNA transcripts. This process is evolutionally made possible by expression of HIV-1 Rev, one of the three HIV-1 proteins encoded by completely spliced HIV-1 RNAs. Evidence has accumulated to suggest that Sam68 plays an important role in HIV-1 replication through HIV-1 Rev protein. In the present study, we further examined the structure-function relationship of Sam68 protein in relation to HIV-1 replication. We identified a Sam68 domain located between aa269 and aa321 to be involved in the HIV-inhibitory effects of Sam68 dominant negative mutants lacking the nuclear localization signal (NLS). Deletion of this domain abrogated inhibition of HIV-1 replication by these mutants. HIV-1 Rev protein appeared to mediate the HIV-inhibitory effects of these mutants and by this domain, as assessed by Rev-dependent chloramphenicol acetyltransferase reporter gene assay, in trans rev-defective HIV-1 complementation assay, and RNase protection assay. The HIV-inhibitory mutants containing this domain were further found to have diminished binding affinity to the wild-type Sam68 and to be associated with cytoplasmic retention of exclusively nuclear localized wild type Sam68. Taken together, these results further ascertain the important role of Sam68 in HIV-1 Rev function and viral replication, and suggest that the HIV-inhibitory effects of Sam68 dominant negative mutants directly result from their binding to endogenous Sam68 and their interference with nuclear localization of endogenous Sam68.
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Affiliation(s)
- Jizhong Zhang
- Department of Microbiology and Immunology, Indiana University School of Medicine, R2 302, 950 W. Walnut St., Indianapolis, IN 46202, United States
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41
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Paronetto MP, Zalfa F, Botti F, Geremia R, Bagni C, Sette C. The nuclear RNA-binding protein Sam68 translocates to the cytoplasm and associates with the polysomes in mouse spermatocytes. Mol Biol Cell 2005; 17:14-24. [PMID: 16221888 PMCID: PMC1345642 DOI: 10.1091/mbc.e05-06-0548] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Translational control plays a crucial role during gametogenesis in organisms as different as worms and mammals. Mouse knockout models have highlighted the essential function of many RNA-binding proteins during spermatogenesis. Herein we have investigated the expression and function during mammalian male meiosis of Sam68, an RNA-binding protein implicated in several aspects of RNA metabolism. Sam68 expression and localization within the cells is stage specific: it is expressed in the nucleus of spermatogonia, it disappears at the onset of meiosis (leptotene/zygotene stages), and it accumulates again in the nucleus of pachytene spermatocytes and round spermatids. During the meiotic divisions, Sam68 translocates to the cytoplasm where it is found associated with the polysomes. Translocation correlates with serine/threonine phosphorylation and it is blocked by inhibitors of the mitogen activated protein kinases ERK1/2 and of the maturation promoting factor cyclinB-cdc2 complex. Both kinases associate with Sam68 in pachytene spermatocytes and phosphorylate the regulatory regions upstream and downstream of the Sam68 RNA-binding motif. Molecular cloning of the mRNAs associated with Sam68 in mouse spermatocytes reveals a subset of genes that might be posttranscriptionally regulated by this RNA-binding protein during spermatogenesis. We also demonstrate that Sam68 shuttles between the nucleus and the cytoplasm in secondary spermatocytes, suggesting that it may promote translation of specific RNA targets during the meiotic divisions.
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Affiliation(s)
- Maria Paola Paronetto
- Department of Public Health and Cell Biology, Section of Anatomy, University of Rome Tor Vergata, 00133 Rome, Italy
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42
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Najib S, Rodríguez-Baño J, Ríos MJ, Muniain MA, Goberna R, Sánchez-Margalet V. Sam68 is tyrosine phosphorylated and recruited to signalling in peripheral blood mononuclear cells from HIV infected patients. Clin Exp Immunol 2005; 141:518-25. [PMID: 16045742 PMCID: PMC1809455 DOI: 10.1111/j.1365-2249.2005.02867.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Human immunodeficiency virus (HIV) codes for a protein, Rev, that mediates the viral RNA export from the nucleus to the cytoplasm. Recently, it has been found that Sam68, the substrate of Src associated in mitosis, is a functional homologue of Rev, and a synergistic activator of Rev activity. Thus, it has been suggested that Sam68 may play an important role in the post-transcriptional regulation of HIV. Sam68 contains an RNA binding motif named KH [homology to the nuclear ribonucleoprotein (hnRNP) K]. Tyrosine phosphorylation of Sam68 and binding to SH3 domains have been found to negatively regulate its RNA binding capacity. Besides, tyrosine phosphorylation of Sam68 allows the formation of signalling complexes with other proteins containing SH2 and SH3 domains, suggesting a role in signal transduction of different systems in human lymphocytes, such as the T cell receptor, and leptin receptor, or the insulin receptor in other cell types. In the present work, we have found that Sam68 is tyrosine phosphorylated in peripheral blood mononuclear cells (PBMC) from HIV infected subjects, leading to the formation of signalling complexes with p85 the regulatory subunit of PI3K, GAP and STAT-3, and decreasing its RNA binding capacity. In contrast, PBMC from HIV infected subjects have lower expression levels of Sam68 compared with controls. These results suggest that Sam68 may play some role in the immune function of lymphocytes in HIV infection.
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Affiliation(s)
- S Najib
- Department of Clinical Biochemistry, Virgen Macarena University Hospital, Seville, Spain
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Zhang J, Li G, Bafica A, Pantelic M, Zhang P, Broxmeyer H, Liu Y, Wetzler L, He JJ, Chen T. Neisseria gonorrhoeae enhances infection of dendritic cells by HIV type 1. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2005; 174:7995-8002. [PMID: 15944306 DOI: 10.4049/jimmunol.174.12.7995] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Clinical studies indicate that Neisseria gonorrhoeae (gonococci (GC)) has the capacity to enhance HIV type 1 (HIV-1) infection. We studied whether GC enhances HIV infection of activated dendritic cells (DCs). The results show that GC can dramatically enhance HIV replication in human DCs during coinfection. The GC component responsible for HIV infection enhancement may be peptidoglycan, which activates TLR2. TLR2 involvement is suggested by bacterial lipoprotein, a TLR2-specific inducer, which stimulates a strong enhancement of HIV infection by human DCs. Moreover, participation of TLR2 is further implicated because GC is unable to stimulate expression of HIV in DCs of TLR2-deficient HIV-1-transgenic mice. These results provide one potential mechanism through which GC infection increases HIV replication in patients infected with both GC and HIV.
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MESH Headings
- Animals
- Antigens, CD
- CD4 Antigens/biosynthesis
- Cell Adhesion Molecules/biosynthesis
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dendritic Cells/microbiology
- Dendritic Cells/virology
- Female
- HIV Infections/immunology
- HIV Infections/microbiology
- HIV Infections/virology
- HIV-1/genetics
- HIV-1/immunology
- HIV-1/pathogenicity
- HeLa Cells
- Histocompatibility Antigens Class I/biosynthesis
- Humans
- Immunoglobulins/biosynthesis
- Lectins, C-Type/biosynthesis
- Lipoproteins/physiology
- Male
- Membrane Glycoproteins/biosynthesis
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/physiology
- Mice
- Mice, Knockout
- Mice, Transgenic
- Monocytes/immunology
- Monocytes/microbiology
- Monocytes/virology
- Neisseria gonorrhoeae/immunology
- Peptidoglycan/pharmacology
- Receptors, CCR5/biosynthesis
- Receptors, CXCR4/biosynthesis
- Receptors, Cell Surface/biosynthesis
- Receptors, Cell Surface/deficiency
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/physiology
- Toll-Like Receptor 2
- Toll-Like Receptors
- Up-Regulation/immunology
- CD83 Antigen
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Affiliation(s)
- Jizhong Zhang
- Department of Microbiology and Immunology, Division of Infectious Diseases, Walther Oncology Center, Walther Oncology Institute, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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44
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Zhou BY, Liu Y, Kim BO, Xiao Y, He JJ. Astrocyte activation and dysfunction and neuron death by HIV-1 Tat expression in astrocytes. Mol Cell Neurosci 2005; 27:296-305. [PMID: 15519244 DOI: 10.1016/j.mcn.2004.07.003] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Revised: 07/01/2004] [Accepted: 07/09/2004] [Indexed: 12/11/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) Tat protein plays an important role in HIV-associated neuropathogenesis. Astrocytosis and neuron death are two hallmarks of HIV-1 infection of the central nervous system (CNS). However, whether there is a direct link between Tat expression, astrocytosis and subsequent neuron death is not known. In this study, we expressed Tat in astrocytes and examined Tat effects on astrocyte function and subsequent neuronal survival. The results showed that Tat expression resulted in a significant increase in glial fibrillary acidic protein (GFAP) expression, a cellular marker of astrocyte activation or astrocytosis. The GFAP promoter-driven reporter gene assay showed that Tat transactivated GFAP expression at the transcriptional level. Furthermore, Tat expression markedly impaired glutamate uptake by astrocytes. Importantly, cell culture supernatants from Tat-expressing astrocytes induced dramatic neuron death. Taken together, these data provide evidence for the first time to directly link Tat expression in astrocytes to astrocytosis, astrocyte dysfunction, and subsequent neuron death. In addition, these data suggest that astrocyte dysfunction contributes, at least in part, to Tat neurotoxicity and subsequently HIV-associated neuropathogenesis.
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Affiliation(s)
- Betty Y Zhou
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Fang J, Kubota S, Yang B, Zhou N, Zhang H, Godbout R, Pomerantz RJ. A DEAD box protein facilitates HIV-1 replication as a cellular co-factor of Rev. Virology 2005; 330:471-80. [PMID: 15567440 DOI: 10.1016/j.virol.2004.09.039] [Citation(s) in RCA: 131] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Revised: 09/21/2004] [Accepted: 09/25/2004] [Indexed: 11/17/2022]
Abstract
HIV-1 Rev escorts unspliced viral mRNAs out of the nucleus of infected cells, which allows formation of infectious HIV-1 virions. We have identified a putative DEAD box (Asp-Glu-Ala-Asp) RNA helicase, DDX1, as a cellular co-factor of Rev, through yeast and mammalian two-hybrid systems using the N-terminal motif of Rev as "bait". DDX1 is not a functional homolog of HIV-1 Rev, but down-regulation of DDX1 resulted in an alternative splicing pattern of Rev-responsive element (RRE)-containing mRNA, and attenuation of Gag p24 antigen production from HLfb rev- cells rescued by exogenous Rev. Co-transfection of a DDX1 expression vector with HIV-1 significantly increased viral production. DDX1 binding to Rev, as well as to the RRE, strongly suggest that DDX1 affects Rev function through the Rev-RRE axis. Moreover, down-regulation of DDX1 altered the steady state subcellular distribution of Rev, from nuclear/nucleolar to cytoplasmic dominance. These findings indicate that DDX1 is a critical cellular co-factor for Rev function, which maintains the proper subcellular distribution of this lentiviral regulatory protein. Therefore, alterations in DDX1-Rev interactions could induce HIV-1 persistence and targeting DDX1 may lead to rationally designed and novel anti-HIV-1 strategies and therapeutics.
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Affiliation(s)
- Jianhua Fang
- Division of Infectious Diseases and Environmental Medicine, Department of Medicine, The Dorrance H. Hamilton Laboratories, Center for Human Virology and Biodefense, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA
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Haegebarth A, Heap D, Bie W, Derry JJ, Richard S, Tyner AL. The nuclear tyrosine kinase BRK/Sik phosphorylates and inhibits the RNA-binding activities of the Sam68-like mammalian proteins SLM-1 and SLM-2. J Biol Chem 2004; 279:54398-404. [PMID: 15471878 DOI: 10.1074/jbc.m409579200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Expression of the intracellular tyrosine kinase BRK/Sik is epithelial-specific and regulated during differentiation. Only a few substrates have been identified for BRK/Sik, including the KH domain containing RNA-binding protein Sam68 and the novel adaptor protein BKS. Although the physiological role of Sam68 is unknown, it has been shown to regulate mRNA transport, pre-mRNA splicing, and polyadenylation. Here we demonstrate that the Sam68-like mammalian proteins SLM-1 and SLM-2 but not the related KH domain containing heterogeneous nuclear ribonucleoprotein K are novel substrates of BRK/Sik. The expression of active BRK/Sik results in increased SLM-1 and SLM-2 phosphorylation and increased retention of BRK/Sik within the nucleus. The phosphorylation of SLM-1 and SLM-2 has functional relevance and leads to inhibition of their RNA-binding abilities. We show that SLM-1, SLM-2, and BRK/Sik have restricted patterns of expression unlike the ubiquitously expressed Sam68. Moreover, BRK/Sik, SLM-1, and Sam68 transcripts were coexpressed in the mouse gastrointestinal tract and skin, suggesting that SLM-1 and Sam68 could be physiologically relevant BRK/Sik targets in vivo. The ability of BRK/Sik to negatively regulate the RNA-binding activities of the KH domain RNA binding proteins SLM-1 and Sam68 may have an impact on the posttranscriptional regulation of epithelial cell gene expression.
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Affiliation(s)
- Andrea Haegebarth
- Departments of Biochemistry and Molecular Genetics, University of Illinois, Chicago, Illinois 60607, USA
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Affiliation(s)
- Eric O Freed
- Virus-Cell Interaction Section, HIV Drug Resistance Program, National Cancer Institute at Frederick, Bldg. 535 Rm. 124 Sultan Street, Frederick, MD 21702-1201, USA.
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McLaren M, Asai K, Cochrane A. A novel function for Sam68: enhancement of HIV-1 RNA 3' end processing. RNA (NEW YORK, N.Y.) 2004; 10:1119-29. [PMID: 15208447 PMCID: PMC1370602 DOI: 10.1261/rna.5263904] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Both cis elements and host cell proteins can significantly affect HIV-1 RNA processing and viral gene expression. Previously, we determined that the exon splicing silencer (ESS3) within the terminal exon of HIV-1 not only reduces use of the adjacent 3' splice site but also prevents Rev-induced export of the unspliced viral RNA to the cytoplasm. In this report, we demonstrate that loss of unspliced viral RNA export is correlated with the inhibition of 3' end processing by the ESS3. Furthermore, we find that the host factor Sam68, a stimulator of HIV-1 protein expression, is able to reverse the block to viral RNA export mediated by the ESS3. The reversal is associated with a stimulation of 3' end processing of the unspliced viral RNA. Our findings identify a novel activity for the ESS3 and Sam68 in regulating HIV-1 RNA polyadenylation. Furthermore, the observations provide an explanation for how Sam68, an exclusively nuclear protein, modulates cytoplasmic utilization of the affected RNAs. Our finding that Sam68 is also able to enhance 3' end processing of a heterologous RNA raises the possibility that it may play a similar role in regulating host gene expression.
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Affiliation(s)
- Meredith McLaren
- Department of Medical Genetics and Microbiology, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
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Affiliation(s)
- Klaus Strebel
- Laboratory of Molecular Microbiology, Viral Biochemistry Section, National Institute of Allergy and Infectious Diseases, NIH, Building-Room 310, 4 Center Drive, MSC 0460, Bethesda, MD 20892-0460, USA.
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50
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Liu Y, Liu H, Kim BO, Gattone VH, Li J, Nath A, Blum J, He JJ. CD4-independent infection of astrocytes by human immunodeficiency virus type 1: requirement for the human mannose receptor. J Virol 2004; 78:4120-33. [PMID: 15047828 PMCID: PMC374297 DOI: 10.1128/jvi.78.8.4120-4133.2004] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection occurs in the central nervous system and causes a variety of neurobehavioral and neuropathological disorders. Both microglia, the residential macrophages in the brain, and astrocytes are susceptible to HIV-1 infection. Unlike microglia that express and utilize CD4 and chemokine coreceptors CCR5 and CCR3 for HIV-1 infection, astrocytes fail to express CD4. Astrocytes express several chemokine coreceptors; however, the involvement of these receptors in astrocyte HIV-1 infection appears to be insignificant. In the present study using an expression cloning strategy, the cDNA for the human mannose receptor (hMR) was found to be essential for CD4-independent HIV-1 infectivity. Ectopic expression of functional hMR rendered U87.MG astrocytic cells susceptible to HIV-1 infection, whereas anti-hMR serum and hMR-specific siRNA blocked HIV-1 infection in human primary astrocytes. In agreement with these findings, hMR bound to HIV-1 virions via the abundant and highly mannosylated sugar moieties of HIV-1 envelope glycoprotein gp120 in a Ca(2+)-dependent fashion. Moreover, hMR-mediated HIV-1 infection was dependent upon endocytic trafficking as assessed by transmission electron microscopy, as well as inhibition of viral entry by endosomo- and lysosomotropic drugs. Taken together, these results demonstrate the direct involvement of hMR in HIV-1 infection of astrocytes and suggest that HIV-1 interaction with hMR plays an important role in HIV-1 neuropathogenesis.
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Affiliation(s)
- Ying Liu
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Hao Liu
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Byung Oh Kim
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Vincent H. Gattone
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Jinliang Li
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Avindra Nath
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Janice Blum
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
| | - Johnny J. He
- Department of Microbiology and Immunology, Walther Oncology Center, Department of Anatomy and Cell Biology, Department of Medicine, Indiana University School of Medicine, Walther Cancer Institute, Indianapolis, Indiana 46202, Department of General Surgery, The First Affiliated Hospital, Xi'an Jiaotong University, Xi'an 710061, People's Republic of China, Department of Neurology, Johns Hopkins University, Baltimore, Maryland 21287
- Corresponding author. Mailing address: Department of Microbiology and Immunology, Indiana University School of Medicine, R2 302, 950 W. Walnut St., Indianapolis, IN 46202. Phone: (317) 274-7525. Fax: (317) 274-7592. E-mail:
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