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Chen S, Jiang Z, Li Q, Pan W, Chen Y, Liu J. Viral RNA capping: Mechanisms and antiviral therapy. J Med Virol 2024; 96:e29622. [PMID: 38682614 DOI: 10.1002/jmv.29622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 03/25/2024] [Accepted: 04/11/2024] [Indexed: 05/01/2024]
Abstract
RNA capping is an essential trigger for protein translation in eukaryotic cells. Many viruses have evolved various strategies for initiating the translation of viral genes and generating progeny virions in infected cells via synthesizing cap structure or stealing the RNA cap from nascent host messenger ribonucleotide acid (mRNA). In addition to protein translation, a new understanding of the role of the RNA cap in antiviral innate immunity has advanced the field of mRNA synthesis in vitro and therapeutic applications. Recent studies on these viral RNA capping systems have revealed startlingly diverse ways and molecular machinery. A comprehensive understanding of how viruses accomplish the RNA capping in infected cells is pivotal for designing effective broad-spectrum antiviral therapies. Here we systematically review the contemporary insights into the RNA-capping mechanisms employed by viruses causing human and animal infectious diseases, while also highlighting its impact on host antiviral innate immune response. The therapeutic applications of targeting RNA capping against viral infections and the development of RNA-capping inhibitors are also summarized.
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Affiliation(s)
- Saini Chen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Zhimin Jiang
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Qiuchen Li
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Wenliang Pan
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yu Chen
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jinhua Liu
- National Key Laboratory of Veterinary Public Health and Safety, College of Veterinary Medicine, China Agricultural University, Beijing, China
- Key Laboratory for Prevention and Control of Avian Influenza and Other Major Poultry Diseases, Ministry of Agriculture and Rural Affairs, College of Veterinary Medicine, China Agricultural University, Beijing, China
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2
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Mbonye U, Karn J. The cell biology of HIV-1 latency and rebound. Retrovirology 2024; 21:6. [PMID: 38580979 PMCID: PMC10996279 DOI: 10.1186/s12977-024-00639-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024] Open
Abstract
Transcriptionally latent forms of replication-competent proviruses, present primarily in a small subset of memory CD4+ T cells, pose the primary barrier to a cure for HIV-1 infection because they are the source of the viral rebound that almost inevitably follows the interruption of antiretroviral therapy. Over the last 30 years, many of the factors essential for initiating HIV-1 transcription have been identified in studies performed using transformed cell lines, such as the Jurkat T-cell model. However, as highlighted in this review, several poorly understood mechanisms still need to be elucidated, including the molecular basis for promoter-proximal pausing of the transcribing complex and the detailed mechanism of the delivery of P-TEFb from 7SK snRNP. Furthermore, the central paradox of HIV-1 transcription remains unsolved: how are the initial rounds of transcription achieved in the absence of Tat? A critical limitation of the transformed cell models is that they do not recapitulate the transitions between active effector cells and quiescent memory T cells. Therefore, investigation of the molecular mechanisms of HIV-1 latency reversal and LRA efficacy in a proper physiological context requires the utilization of primary cell models. Recent mechanistic studies of HIV-1 transcription using latently infected cells recovered from donors and ex vivo cellular models of viral latency have demonstrated that the primary blocks to HIV-1 transcription in memory CD4+ T cells are restrictive epigenetic features at the proviral promoter, the cytoplasmic sequestration of key transcription initiation factors such as NFAT and NF-κB, and the vanishingly low expression of the cellular transcription elongation factor P-TEFb. One of the foremost schemes to eliminate the residual reservoir is to deliberately reactivate latent HIV-1 proviruses to enable clearance of persisting latently infected cells-the "Shock and Kill" strategy. For "Shock and Kill" to become efficient, effective, non-toxic latency-reversing agents (LRAs) must be discovered. Since multiple restrictions limit viral reactivation in primary cells, understanding the T-cell signaling mechanisms that are essential for stimulating P-TEFb biogenesis, initiation factor activation, and reversing the proviral epigenetic restrictions have become a prerequisite for the development of more effective LRAs.
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Affiliation(s)
- Uri Mbonye
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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Peng D, Huang Z, Yang H, Luo Y, Wu Z. PPM1G regulates hepatic ischemia/reperfusion injury through STING-mediated inflammatory pathways in macrophages. Immun Inflamm Dis 2024; 12:e1189. [PMID: 38372470 PMCID: PMC10875902 DOI: 10.1002/iid3.1189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 01/08/2024] [Accepted: 02/04/2024] [Indexed: 02/20/2024] Open
Abstract
BACKGROUND Ischemia/reperfusion injury (IRI) is generally unavoidable following liver transplantation. Here, we investigated the role of protein phosphatase, Mg2+ /Mn2+ dependent 1G (PPM1G) in hepatic IRI. METHODS Hepatic IRI was mimicked by employing a hypoxia/reperfusion (H/R) model in RAW 264.7 cells and a 70% warm ischemia model in C57BL/6 mice, respectively. In vitro, expression changes of tumor necrosis factor-α and interleukin were detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and enzyme-linked immunosorbent assay. The protein expressions of PPM1G and the stimulator of interferon genes (STING) pathway components were analyzed by western blot. Interaction between PPM1G and STING was verified by coimmunoprecipitation (CO-IP). Immunofluorescence was applied for detection of p-IRF3. Flow cytometry, qRT-PCR and western blot were utilized to analyze markers of macrophage polarization. In vivo, histological analyses of mice liver were carried out by TUNEL and H&E staining. Changes in serum aminotransferases were also detected. RESULTS Following H/R intervention, a steady decline in PPM1G along with an increase in inflammatory cytokines in vitro was observed. Addition of plasmid with PPM1G sequence limited the release of inflammatory cytokines and downregulated phosphorylation of STING. CO-IP validated the interaction between PPM1G and STING. Furthermore, inhibition of PPM1G with lentivirus enhanced phosphorylation of STING and its downstream components; meanwhile, p65, p38, and Jnk were also surged to phosphorylation. Expression of INOS and CD86 was surged, while CD206, Arg-1, and IL-10 were inhibited. In vivo, PPM1G inhibition further promoted liver damage, hepatocyte apoptosis, and transaminases release. Selective inhibition of STING with C-176 partially reversed the activation of STING pathway and inflammatory cytokines in vitro. M1 markers were also suppressed by C-176. In vivo, C-176 rescued liver damage and transaminase release caused by PPM1G inhibition. CONCLUSION PPM1G suppresses hepatic IRI and macrophage M1 phenotype by repressing STING-mediated inflammatory pathways.
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Affiliation(s)
- Dadi Peng
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Zuotian Huang
- Department of Hepatobiliary Pancreatic Tumor CenterChongqing University Cancer HospitalChongqingChina
| | - Hang Yang
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Yunhai Luo
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
| | - Zhongjun Wu
- Department of Hepatobiliary SurgeryThe First Affiliated Hospital of Chongqing Medical UniversityChongqingChina
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Carpenter MA, Temiz NA, Ibrahim MA, Jarvis MC, Brown MR, Argyris PP, Brown WL, Starrett GJ, Yee D, Harris RS. Mutational impact of APOBEC3A and APOBEC3B in a human cell line and comparisons to breast cancer. PLoS Genet 2023; 19:e1011043. [PMID: 38033156 PMCID: PMC10715669 DOI: 10.1371/journal.pgen.1011043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 12/12/2023] [Accepted: 10/30/2023] [Indexed: 12/02/2023] Open
Abstract
A prominent source of mutation in cancer is single-stranded DNA cytosine deamination by cellular APOBEC3 enzymes, which results in signature C-to-T and C-to-G mutations in TCA and TCT motifs. Although multiple enzymes have been implicated, reports conflict and it is unclear which protein(s) are responsible. Here we report the development of a selectable system to quantify genome mutation and demonstrate its utility by comparing the mutagenic activities of three leading candidates-APOBEC3A, APOBEC3B, and APOBEC3H. The human cell line, HAP1, is engineered to express the thymidine kinase (TK) gene of HSV-1, which confers sensitivity to ganciclovir. Expression of APOBEC3A and APOBEC3B, but not catalytic mutant controls or APOBEC3H, triggers increased frequencies of TK mutation and similar TC-biased cytosine mutation profiles in the selectable TK reporter gene. Whole genome sequences from independent clones enabled an analysis of thousands of single base substitution mutations and extraction of local sequence preferences with APOBEC3A preferring YTCW motifs 70% of the time and APOBEC3B 50% of the time (Y = C/T; W = A/T). Signature comparisons with breast tumor whole genome sequences indicate that most malignancies manifest intermediate percentages of APOBEC3 signature mutations in YTCW motifs, mostly between 50 and 70%, suggesting that both enzymes contribute in a combinatorial manner to the overall mutation landscape. Although the vast majority of APOBEC3A- and APOBEC3B-induced single base substitution mutations occur outside of predicted chromosomal DNA hairpin structures, whole genome sequence analyses and supporting biochemical studies also indicate that both enzymes are capable of deaminating the single-stranded loop regions of DNA hairpins at elevated rates. These studies combine to help resolve a long-standing etiologic debate on the source of APOBEC3 signature mutations in cancer and indicate that future diagnostic and therapeutic efforts should focus on both APOBEC3A and APOBEC3B.
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Affiliation(s)
- Michael A. Carpenter
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Health San Antonio, San Antonio, Texas, United States of America
| | - Nuri A. Temiz
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
- Institute for Health Informatics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Mahmoud A. Ibrahim
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas, United States of America
| | - Matthew C. Jarvis
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Margaret R. Brown
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Prokopios P. Argyris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - William L. Brown
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Gabriel J. Starrett
- Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland, United States of America
| | - Douglas Yee
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America
| | - Reuben S. Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, United States of America
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Health San Antonio, San Antonio, Texas, United States of America
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Wu X, Xie Y, Zhao K, Lu J. Targeting the super elongation complex for oncogenic transcription driven tumor malignancies: Progress in structure, mechanisms and small molecular inhibitor discovery. Adv Cancer Res 2023; 158:387-421. [PMID: 36990537 DOI: 10.1016/bs.acr.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Oncogenic transcription activation is associated with tumor development and resistance derived from chemotherapy or target therapy. The super elongation complex (SEC) is an important complex regulating gene transcription and expression in metazoans closely related to physiological activities. In normal transcriptional regulation, SEC can trigger promoter escape, limit proteolytic degradation of transcription elongation factors and increase the synthesis of RNA polymerase II (POL II), and regulate many normal human genes to stimulate RNA elongation. Dysregulation of SEC accompanied by multiple transcription factors in cancer promotes rapid transcription of oncogenes and induce cancer development. In this review, we summarized recent progress in understanding the mechanisms of SEC in regulating normal transcription, and importantly its roles in cancer development. We also highlighted the discovery of SEC complex target related inhibitors and their potential applications in cancer treatment.
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Affiliation(s)
- Xinyu Wu
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China; Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Yanqiu Xie
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China; Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Kehao Zhao
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China.
| | - Jing Lu
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation (Yantai University), Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China.
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Detering NT, Schüning T, Hensel N, Claus P. The phospho-landscape of the survival of motoneuron protein (SMN) protein: relevance for spinal muscular atrophy (SMA). Cell Mol Life Sci 2022; 79:497. [PMID: 36006469 PMCID: PMC11071818 DOI: 10.1007/s00018-022-04522-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 07/27/2022] [Accepted: 08/09/2022] [Indexed: 11/03/2022]
Abstract
Spinal muscular atrophy (SMA) is caused by low levels of the survival of motoneuron (SMN) Protein leading to preferential degeneration of lower motoneurons in the ventral horn of the spinal cord and brain stem. However, the SMN protein is ubiquitously expressed and there is growing evidence of a multisystem phenotype in SMA. Since a loss of SMN function is critical, it is important to decipher the regulatory mechanisms of SMN function starting on the level of the SMN protein itself. Posttranslational modifications (PTMs) of proteins regulate multiple functions and processes, including activity, cellular trafficking, and stability. Several PTM sites have been identified within the SMN sequence. Here, we map the identified SMN PTMs highlighting phosphorylation as a key regulator affecting localization, stability and functions of SMN. Furthermore, we propose SMN phosphorylation as a crucial factor for intracellular interaction and cellular distribution of SMN. We outline the relevance of phosphorylation of the spinal muscular atrophy (SMA) gene product SMN with regard to basic housekeeping functions of SMN impaired in this neurodegenerative disease. Finally, we compare SMA patient mutations with putative and verified phosphorylation sites. Thus, we emphasize the importance of phosphorylation as a cellular modulator in a clinical perspective as a potential additional target for combinatorial SMA treatment strategies.
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Affiliation(s)
- Nora Tula Detering
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Tobias Schüning
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Niko Hensel
- Ottawa Hospital Research Institute (OHRI), Ottawa, Canada
- Center for Systems Neuroscience (ZSN), Hannover, Germany
| | - Peter Claus
- SMATHERIA gGmbH - Non-Profit Biomedical Research Institute, Hannover, Germany.
- Center for Systems Neuroscience (ZSN), Hannover, Germany.
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van Heuvel Y, Schatz S, Rosengarten JF, Stitz J. Infectious RNA: Human Immunodeficiency Virus (HIV) Biology, Therapeutic Intervention, and the Quest for a Vaccine. Toxins (Basel) 2022; 14:toxins14020138. [PMID: 35202165 PMCID: PMC8876946 DOI: 10.3390/toxins14020138] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/02/2022] [Accepted: 02/09/2022] [Indexed: 11/16/2022] Open
Abstract
Different mechanisms mediate the toxicity of RNA. Genomic retroviral mRNA hijacks infected host cell factors to enable virus replication. The viral genomic RNA of the human immunodeficiency virus (HIV) encompasses nine genes encoding in less than 10 kb all proteins needed for replication in susceptible host cells. To do so, the genomic RNA undergoes complex alternative splicing to facilitate the synthesis of the structural, accessory, and regulatory proteins. However, HIV strongly relies on the host cell machinery recruiting cellular factors to complete its replication cycle. Antiretroviral therapy (ART) targets different steps in the cycle, preventing disease progression to the acquired immunodeficiency syndrome (AIDS). The comprehension of the host immune system interaction with the virus has fostered the development of a variety of vaccine platforms. Despite encouraging provisional results in vaccine trials, no effective vaccine has been developed, yet. However, novel promising vaccine platforms are currently under investigation.
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Affiliation(s)
- Yasemin van Heuvel
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Institute of Technical Chemistry, Leibniz University Hannover, Callinstraße 3-9, 30167 Hannover, Germany
| | - Stefanie Schatz
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Institute of Technical Chemistry, Leibniz University Hannover, Callinstraße 3-9, 30167 Hannover, Germany
| | - Jamila Franca Rosengarten
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Institute of Technical Chemistry, Leibniz University Hannover, Callinstraße 3-9, 30167 Hannover, Germany
| | - Jörn Stitz
- Research Group Pharmaceutical Biotechnology, Faculty of Applied Natural Sciences, TH Köln—University of Applied Sciences, Chempark Leverkusen, Kaiser-Wilhelm-Allee, 51368 Leverkusen, Germany; (Y.v.H.); (S.S.); (J.F.R.)
- Correspondence:
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8
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Liu Y, Li L, Timani K, White C, He JJ. Tip110 Expression Facilitates the Release of HEXIM1 and pTEFb from the 7SK Ribonucleoprotein Complex Involving Regulation of the Intracellular Redox Level. Aging Dis 2021; 12:2113-2124. [PMID: 34881089 PMCID: PMC8612609 DOI: 10.14336/ad.2021.0528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 05/28/2021] [Indexed: 11/18/2022] Open
Abstract
HIV-1 Tat-interacting protein of 110 kDa (Tip110; p110nrb/SART3) has been identified to be important for HIV gene transcription and several host gene expression. In this study, we showed that Tip110 was present in the 7SK snRNP through direct binding to MEPCE, a component of the 7SK snRNP complex. In addition, we found a positive association between Tip110 expression, change of HEXIM1 from dimer/oligomer to monomer, and release of HEXIM1 and P-TEFb from the 7SK snRNP complex. A similar association was also noted specifically in nuclear matrix as well as in chromatin where the free HEXIM1 and 7SK snRNP-bound HEXIM1 are located. Moreover, we demonstrated that Tip110 expression was linked to the glutathione metabolic pathway and the intracellular redox level, which in turn regulated HEXIM1 dimerization/oligomerization. Lastly, we performed the FRET microscopic analysis and confirmed the direct relationship between Tip110 expression and HEXIM1 dimerization/oligomerization in vivo. Taken together, these results identified a new mechanism governing HEXIM1 dimerization/oligomerization and the release of HEXIM1 and P-TEFb from the 7SK snRNP complex. These results also yield new insights to the roles of Tip110 in HIV gene transcription and replication.
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Affiliation(s)
- Ying Liu
- 1Department of Microbiology and Immunology.,2Center for Cancer Cell Biology, Immunology and Infection, and
| | - Lu Li
- 1Department of Microbiology and Immunology.,2Center for Cancer Cell Biology, Immunology and Infection, and
| | - Khalid Timani
- 1Department of Microbiology and Immunology.,2Center for Cancer Cell Biology, Immunology and Infection, and
| | - Carl White
- 2Center for Cancer Cell Biology, Immunology and Infection, and.,3Department of Physiology and Biophysics, Rosalind Franklin University of Medicine and Science Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064, USA
| | - Johnny J He
- 1Department of Microbiology and Immunology.,2Center for Cancer Cell Biology, Immunology and Infection, and
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Xiong DL, Li Q, Wang H, Jin WL, Fan XM, Ma YY. High expression of PPM1G is associated with the progression and poor prognosis of hepatocellular carcinoma. Cancer Biomark 2021; 34:13-22. [PMID: 34366322 DOI: 10.3233/cbm-203248] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND PPM1G, a member of the serine/threonine protease family, dephosphorylates various proteins and may be involved in cancer development. The role and mechanism of PPM1G in HCC still needs to be verified. OBJECTIVE This study aims to explore the role of PPM1G in the occurrence, development and prognosis of HCC. METHODS Using bioinformatics (UALCAN, cBioPortal, Linkedomics, STRING and GSEA) to analyze the expression of PPM1G mRNA in HCC, its clinical relevance and possible involved signaling pathways. The expression of PPM1G protein was determined by immunohistochemistry in 311 cases of HCC to evaluate the association between PPM1G and clinical features and prognosis. RESULTS The expression of PPM1G was significantly upregulated in HCC (P< 0.001), correlated with the metastasis (P= 0.020), pathological grade of HCC (P= 0.032), microvascular invasion (P= 0.040), and HBV infection (P= 0.041). Cox multivariate regression showed high expression of PPM1G was an independent prognostic factor for HCC. Its role in HCC may relate to methylation and frequency mutation. Furthermore, the database showed PPM1G is involved in the signal pathway such as cell cycle, WNT pathway, and mTOR pathway in HCC. CONCLUSION PPM1G showed an essential function involving in tumor-related pathways in HCC, providing a biological basis for targeted treatment of HCC clinically.
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Affiliation(s)
- Dan-Lei Xiong
- Department of Ultrasound, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China.,Department of Ultrasound, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Qian Li
- Graduate Department, Bengbu Medical College, Bengbu, Anhui, China.,Department of Ultrasound, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Heng Wang
- Graduate Department, Bengbu Medical College, Bengbu, Anhui, China
| | - Wei-Li Jin
- Department of Gastroenterology, Nanxun People's Hospital (Zhejiang Provincial People's Hospital Nanxun Branch), Huzhou, Zhejiang, China
| | - Xiao-Ming Fan
- Department of Ultrasound, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Ying-Yu Ma
- Key Laboratory of Gastroenterology of Zhejiang Province, Zhejiang Provincial People's Hospital, People's Hospital of Hangzhou Medical College, Hangzhou, Zhejiang, China
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Chen D, Zhao Z, Chen L, Li Q, Zou J, Liu S. PPM1G promotes the progression of hepatocellular carcinoma via phosphorylation regulation of alternative splicing protein SRSF3. Cell Death Dis 2021; 12:722. [PMID: 34290239 PMCID: PMC8295330 DOI: 10.1038/s41419-021-04013-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 07/06/2021] [Accepted: 07/07/2021] [Indexed: 12/14/2022]
Abstract
Emerging evidence has demonstrated that alternative splicing has a vital role in regulating protein function, but how alternative splicing factors can be regulated remains unclear. We showed that the PPM1G, a protein phosphatase, regulated the phosphorylation of SRSF3 in hepatocellular carcinoma (HCC) and contributed to the proliferation, invasion, and metastasis of HCC. PPM1G was highly expressed in HCC tissues compared to adjacent normal tissues, and higher levels of PPM1G were observed in adverse staged HCCs. The higher levels of PPM1G were highly correlated with poor prognosis, which was further validated in the TCGA cohort. The knockdown of PPM1G inhibited the cell growth and invasion of HCC cell lines. Further studies showed that the knockdown of PPM1G inhibited tumor growth in vivo. The mechanistic analysis showed that the PPM1G interacted with proteins related to alternative splicing, including SRSF3. Overexpression of PPM1G promoted the dephosphorylation of SRSF3 and changed the alternative splicing patterns of genes related to the cell cycle, the transcriptional regulation in HCC cells. In addition, we also demonstrated that the promoter of PPM1G was activated by multiple transcription factors and co-activators, including MYC/MAX and EP300, MED1, and ELF1. Our study highlighted the essential role of PPM1G in HCC and shed new light on unveiling the regulation of alternative splicing in malignant transformation.
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Affiliation(s)
- Dawei Chen
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Zhenguo Zhao
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Lu Chen
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Qinghua Li
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China
| | - Jixue Zou
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, No. 180, Fenglin Road, Shanghai, 200032, China.
| | - Shuanghai Liu
- Department of Hepatopancreatobiliary Surgery, Jiangyin People's Hospital, School of Medicine, Southeast University, No. 163, Shoushan Road, Jiangyin, 214400, Jiangsu Province, China.
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11
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CDK9 keeps RNA polymerase II on track. Cell Mol Life Sci 2021; 78:5543-5567. [PMID: 34146121 PMCID: PMC8257543 DOI: 10.1007/s00018-021-03878-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 05/26/2021] [Accepted: 06/08/2021] [Indexed: 12/30/2022]
Abstract
Cyclin-dependent kinase 9 (CDK9), the kinase component of positive transcription elongation factor b (P-TEFb), is essential for transcription of most protein-coding genes by RNA polymerase II (RNAPII). By releasing promoter-proximally paused RNAPII into gene bodies, CDK9 controls the entry of RNAPII into productive elongation and is, therefore, critical for efficient synthesis of full-length messenger (m)RNAs. In recent years, new players involved in P-TEFb-dependent processes have been identified and an important function of CDK9 in coordinating elongation with transcription initiation and termination has been unveiled. As the regulatory functions of CDK9 in gene expression continue to expand, a number of human pathologies, including cancers, have been associated with aberrant CDK9 activity, underscoring the need to properly regulate CDK9. Here, I provide an overview of CDK9 function and regulation, with an emphasis on CDK9 dysregulation in human diseases.
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12
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Anshabo AT, Milne R, Wang S, Albrecht H. CDK9: A Comprehensive Review of Its Biology, and Its Role as a Potential Target for Anti-Cancer Agents. Front Oncol 2021; 11:678559. [PMID: 34041038 PMCID: PMC8143439 DOI: 10.3389/fonc.2021.678559] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 04/16/2021] [Indexed: 12/25/2022] Open
Abstract
Cyclin-dependent kinases (CDKs) are proteins pivotal to a wide range of cellular functions, most importantly cell division and transcription, and their dysregulations have been implicated as prominent drivers of tumorigenesis. Besides the well-established role of cell cycle CDKs in cancer, the involvement of transcriptional CDKs has been confirmed more recently. Most cancers overtly employ CDKs that serve as key regulators of transcription (e.g., CDK9) for a continuous production of short-lived gene products that maintain their survival. As such, dysregulation of the CDK9 pathway has been observed in various hematological and solid malignancies, making it a valuable anticancer target. This therapeutic potential has been utilized for the discovery of CDK9 inhibitors, some of which have entered human clinical trials. This review provides a comprehensive discussion on the structure and biology of CDK9, its role in solid and hematological cancers, and an updated review of the available inhibitors currently being investigated in preclinical and clinical settings.
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Affiliation(s)
- Abel Tesfaye Anshabo
- Drug Discovery and Development, Centre for Cancer Diagnostics and Therapeutics, Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Robert Milne
- Drug Discovery and Development, Centre for Cancer Diagnostics and Therapeutics, Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Shudong Wang
- Drug Discovery and Development, Centre for Cancer Diagnostics and Therapeutics, Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
| | - Hugo Albrecht
- Drug Discovery and Development, Centre for Cancer Diagnostics and Therapeutics, Clinical and Health Sciences, University of South Australia, Adelaide, SA, Australia
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13
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The 7SK/P-TEFb snRNP controls ultraviolet radiation-induced transcriptional reprogramming. Cell Rep 2021; 35:108965. [PMID: 33852864 DOI: 10.1016/j.celrep.2021.108965] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 01/27/2021] [Accepted: 03/17/2021] [Indexed: 01/08/2023] Open
Abstract
Conversion of promoter-proximally paused RNA polymerase II (RNAPII) into elongating polymerase by the positive transcription elongation factor b (P-TEFb) is a central regulatory step of mRNA synthesis. The activity of P-TEFb is controlled mainly by the 7SK small nuclear ribonucleoprotein (snRNP), which sequesters active P-TEFb into inactive 7SK/P-TEFb snRNP. Here we demonstrate that under normal culture conditions, the lack of 7SK snRNP has only minor impacts on global RNAPII transcription without detectable consequences on cell proliferation. However, upon ultraviolet (UV)-light-induced DNA damage, cells lacking 7SK have a defective transcriptional response and reduced viability. Both UV-induced release of "lesion-scanning" polymerases and activation of key early-responsive genes are compromised in the absence of 7SK. Proper induction of 7SK-dependent UV-responsive genes requires P-TEFb activity directly mobilized from the nucleoplasmic 7SK/P-TEFb snRNP. Our data demonstrate that the primary function of the 7SK/P-TEFb snRNP is to orchestrate the proper transcriptional response to stress.
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14
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The ARF tumor suppressor targets PPM1G/PP2Cγ to counteract NF-κB transcription tuning cell survival and the inflammatory response. Proc Natl Acad Sci U S A 2020; 117:32594-32605. [PMID: 33288725 DOI: 10.1073/pnas.2004470117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Inducible transcriptional programs mediate the regulation of key biological processes and organismal functions. Despite their complexity, cells have evolved mechanisms to precisely control gene programs in response to environmental cues to regulate cell fate and maintain normal homeostasis. Upon stimulation with proinflammatory cytokines such as tumor necrosis factor-α (TNF), the master transcriptional regulator nuclear factor (NF)-κB utilizes the PPM1G/PP2Cγ phosphatase as a coactivator to normally induce inflammatory and cell survival programs. However, how PPM1G activity is precisely regulated to control NF-κB transcription magnitude and kinetics remains unknown. Here, we describe a mechanism by which the ARF tumor suppressor binds PPM1G to negatively regulate its coactivator function in the NF-κB circuit thereby promoting insult resolution. ARF becomes stabilized upon binding to PPM1G and forms a ternary protein complex with PPM1G and NF-κB at target gene promoters in a stimuli-dependent manner to provide tunable control of the NF-κB transcriptional program. Consistently, loss of ARF in colon epithelial cells leads to up-regulation of NF-κB antiapoptotic genes upon TNF stimulation and renders cells partially resistant to TNF-induced apoptosis in the presence of agents blocking the antiapoptotic program. Notably, patient tumor data analysis validates these findings by revealing that loss of ARF strongly correlates with sustained expression of inflammatory and cell survival programs. Collectively, we propose that PPM1G emerges as a therapeutic target in a variety of cancers arising from ARF epigenetic silencing, to loss of ARF function, as well as tumors bearing oncogenic NF-κB activation.
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15
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Ramdas P, Sahu AK, Mishra T, Bhardwaj V, Chande A. From Entry to Egress: Strategic Exploitation of the Cellular Processes by HIV-1. Front Microbiol 2020; 11:559792. [PMID: 33343516 PMCID: PMC7746852 DOI: 10.3389/fmicb.2020.559792] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 11/05/2020] [Indexed: 01/23/2023] Open
Abstract
HIV-1 employs a rich arsenal of viral factors throughout its life cycle and co-opts intracellular trafficking pathways. This exquisitely coordinated process requires precise manipulation of the host microenvironment, most often within defined subcellular compartments. The virus capitalizes on the host by modulating cell-surface proteins and cleverly exploiting nuclear import pathways for post entry events, among other key processes. Successful virus–cell interactions are indeed crucial in determining the extent of infection. By evolving defenses against host restriction factors, while simultaneously exploiting host dependency factors, the life cycle of HIV-1 presents a fascinating montage of an ongoing host–virus arms race. Herein, we provide an overview of how HIV-1 exploits native functions of the host cell and discuss recent findings that fundamentally change our understanding of the post-entry replication events.
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Affiliation(s)
- Pavitra Ramdas
- Molecular Virology Laboratory, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, India
| | - Amit Kumar Sahu
- Molecular Virology Laboratory, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, India
| | - Tarun Mishra
- Molecular Virology Laboratory, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, India
| | - Vipin Bhardwaj
- Molecular Virology Laboratory, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, India
| | - Ajit Chande
- Molecular Virology Laboratory, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal, India
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16
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Sharma V, Montano MM. Non-epigenetic induction of HEXIM1 by DNMT1 inhibitors and functional relevance. Sci Rep 2020; 10:21015. [PMID: 33273553 PMCID: PMC7713402 DOI: 10.1038/s41598-020-78058-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 11/17/2020] [Indexed: 11/09/2022] Open
Abstract
We have been studying the role of Hexamethylene bisacetamide (HMBA) Induced Protein 1 (HEXIM1) as a tumor suppressor whose expression is decreased in breast and prostate cancer. The anti-cancer actions of HEXIM1 in melanomas and AML have been reported by other groups. Previous studies have shown that 5-Aza-2'deoxycytidine (5-AzadC), a DNMT1 inhibitor, induces re-expression of tumor suppressor genes by removing/erasing methylation marks from their promoters. Our studies highlighted another mechanism wherein 5-AzadC induced DNA damage, which then resulted in enhanced occupancy of NF-ĸB, P-TEFb, and serine 2 phosphorylated RNA Polymerase II on the HEXIM1 gene. As a consequence, 5-AzadC induced HEXIM1 expression in prostate cancer cell lines and triple negative breast cancers. 5-AzadC-induced DNA damage enhanced P-TEFb occupancy via a mechanism that involved activation of ATR and ATM and induction of NF-ĸB recruitment to the HEXIM1 promoter. Downregulation of NF-ĸB attenuated 5-AzadC-induced HEXIM1 expression in prostate and breast cancer cells. The functional relevance of 5-AzadC-induced HEXIM1 expression is revealed by studies showing the HEXIM1 is required for the induction of apoptosis. Collectively, our findings support a non-epigenetic mechanism for 5-AzadC-induced re-expression of HEXIM1 protein, and may contribute to the clinical efficacy of 5-AzadC.
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Affiliation(s)
- Vikas Sharma
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH, 44106, USA
| | - Monica M Montano
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Ave., Cleveland, OH, 44106, USA.
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17
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Depicting HIV-1 Transcriptional Mechanisms: A Summary of What We Know. Viruses 2020; 12:v12121385. [PMID: 33287435 PMCID: PMC7761857 DOI: 10.3390/v12121385] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 11/26/2020] [Accepted: 12/01/2020] [Indexed: 12/19/2022] Open
Abstract
Despite the introduction of combinatory antiretroviral therapy (cART), HIV-1 infection cannot be cured and is still one of the major health issues worldwide. Indeed, as soon as cART is interrupted, a rapid rebound of viremia is observed. The establishment of viral latency and the persistence of the virus in cellular reservoirs constitute the main barrier to HIV eradication. For this reason, new therapeutic approaches have emerged to purge or restrain the HIV-1 reservoirs in order to cure infected patients. However, the viral latency is a multifactorial process that depends on various cellular mechanisms. Since these new therapies mainly target viral transcription, their development requires a detailed and precise understanding of the regulatory mechanism underlying HIV-1 transcription. In this review, we discuss the complex molecular transcriptional network regulating HIV-1 gene expression by focusing on the involvement of host cell factors that could be used as potential drug targets to design new therapeutic strategies and, to a larger extent, to reach an HIV-1 functional cure.
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18
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Yu K, Tian H, Deng H. PPM1G restricts innate immune signaling mediated by STING and MAVS and is hijacked by KSHV for immune evasion. SCIENCE ADVANCES 2020; 6:6/47/eabd0276. [PMID: 33219031 PMCID: PMC7679160 DOI: 10.1126/sciadv.abd0276] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 10/07/2020] [Indexed: 05/10/2023]
Abstract
The adaptor proteins, STING and MAVS, are components of critical pathogen-sensing pathways that induce innate immunity. Phosphorylation of either adaptor results in activation of the type I interferon pathway. How this phosphorylation is regulated and how it is manipulated by pathogens remain largely unknown. Here, we identified host protein phosphatase, Mg2+/Mn2+ dependent 1G (PPM1G) as a negative regulator of innate immune pathways and showed that this host system is hijacked by Kaposi's sarcoma-associated herpesvirus (KSHV). Mechanistically, KSHV tegument protein ORF33 interacts with STING/MAVS and enhances recruitment of PPM1G to dephosphorylate p-STING/p-MAVS for immunosuppression. Inhibition of PPM1G expression improves the antiviral response against both DNA and RNA viruses. Collectively, our study shows that PPM1G restricts both cytosolic DNA- and RNA-sensing pathways to naturally balance the intensity of the antiviral response. Manipulation of PPM1G by KSHV provides an important strategy for immune evasion.
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Affiliation(s)
- Kuai Yu
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huabin Tian
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hongyu Deng
- CAS Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
- University of Chinese Academy of Sciences, Beijing 100049, China
- CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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19
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Noncoding RNAs Set the Stage for RNA Polymerase II Transcription. Trends Genet 2020; 37:279-291. [PMID: 33046273 DOI: 10.1016/j.tig.2020.09.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 09/11/2020] [Accepted: 09/14/2020] [Indexed: 12/24/2022]
Abstract
Effective synthesis of mammalian messenger (m)RNAs depends on many factors that together direct RNA polymerase II (pol II) through the different stages of the transcription cycle and ensure efficient cotranscriptional processing of mRNAs. In addition to the many proteins involved in transcription initiation, elongation, and termination, several noncoding (nc)RNAs also function as global transcriptional regulators. Understanding the mode of action of these non-protein regulators has been an intense area of research in recent years. Here, we describe how these ncRNAs influence key regulatory steps of the transcription process, to affect large numbers of genes. Through direct association with pol II or by modulating the activity of transcription or RNA processing factors, these regulatory RNAs perform critical roles in gene expression.
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20
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Cassandri M, Fioravanti R, Pomella S, Valente S, Rotili D, Del Baldo G, De Angelis B, Rota R, Mai A. CDK9 as a Valuable Target in Cancer: From Natural Compounds Inhibitors to Current Treatment in Pediatric Soft Tissue Sarcomas. Front Pharmacol 2020; 11:1230. [PMID: 32903585 PMCID: PMC7438590 DOI: 10.3389/fphar.2020.01230] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/28/2020] [Indexed: 12/20/2022] Open
Abstract
Cyclin-Dependent Kinases (CDKs) are well-known reliable targets for cancer treatment being often deregulated. Among them, since the transcription-associated CDK9 represents the sentry of cell transcriptional homeostasis, it can be a valuable target for managing cancers in which the transcriptional machinery is dysregulated by tumor-driver oncogenes. Here we give an overview of some natural compounds identified as CDK inhibitors with reported activity also against CDK9, that were taken as a model for the development of highly active synthetic anti-CDK9 agents. After, we summarize the data on CDK9 inhibition in a group of rare pediatric solid tumors such as rhabdomyosarcoma, Ewing’s sarcoma, synovial sarcoma and malignant rhabdoid tumors (soft tissue sarcomas), highlighting the more recent results in this field. Finally, we discuss the perspective and challenge of CDK9 modulation in cancer.
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Affiliation(s)
- Matteo Cassandri
- Department of Oncohematology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Rossella Fioravanti
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
| | - Silvia Pomella
- Department of Oncohematology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Sergio Valente
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
| | - Dante Rotili
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
| | - Giada Del Baldo
- Department of Oncohematology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Biagio De Angelis
- Department of Oncohematology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Rossella Rota
- Department of Oncohematology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Antonello Mai
- Department of Drug Chemistry and Technologies, Sapienza University of Rome, Rome, Italy
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21
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Metal-dependent Ser/Thr protein phosphatase PPM family: Evolution, structures, diseases and inhibitors. Pharmacol Ther 2020; 215:107622. [PMID: 32650009 DOI: 10.1016/j.pharmthera.2020.107622] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/29/2020] [Indexed: 02/06/2023]
Abstract
Protein phosphatases and kinases control multiple cellular events including proliferation, differentiation, and stress responses through regulating reversible protein phosphorylation, the most important post-translational modification. Members of metal-dependent protein phosphatase (PPM) family, also known as PP2C phosphatases, are Ser/Thr phosphatases that bind manganese/magnesium ions (Mn2+/Mg2+) in their active center and function as single subunit enzymes. In mammals, there are 20 isoforms of PPM phosphatases: PPM1A, PPM1B, PPM1D, PPM1E, PPM1F, PPM1G, PPM1H, PPM1J, PPM1K, PPM1L, PPM1M, PPM1N, ILKAP, PDP1, PDP2, PHLPP1, PHLPP2, PP2D1, PPTC7, and TAB1, whereas there are only 8 in yeast. Phylogenetic analysis of the DNA sequences of vertebrate PPM isoforms revealed that they can be divided into 12 different classes: PPM1A/PPM1B/PPM1N, PPM1D, PPM1E/PPM1F, PPM1G, PPM1H/PPM1J/PPM1M, PPM1K, PPM1L, ILKAP, PDP1/PDP2, PP2D1/PHLPP1/PHLPP2, TAB1, and PPTC7. PPM-family members have a conserved catalytic core region, which contains the metal-chelating residues. The different isoforms also have isoform specific regions within their catalytic core domain and terminal domains, and these regions may be involved in substrate recognition and/or functional regulation of the phosphatases. The twenty mammalian PPM phosphatases are involved in regulating diverse cellular functions, such as cell cycle control, cell differentiation, immune responses, and cell metabolism. Mutation, overexpression, or deletion of the PPM phosphatase gene results in abnormal cellular responses, which lead to various human diseases. This review focuses on the structures and biological functions of the PPM-phosphatase family and their associated diseases. The development of specific inhibitors against the PPM phosphatase family as a therapeutic strategy will also be discussed.
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22
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Serebrenik AA, Argyris PP, Jarvis MC, Brown WL, Bazzaro M, Vogel RI, Erickson BK, Lee SH, Goergen KM, Maurer MJ, Heinzen EP, Oberg AL, Huang Y, Hou X, Weroha SJ, Kaufmann SH, Harris RS. The DNA Cytosine Deaminase APOBEC3B is a Molecular Determinant of Platinum Responsiveness in Clear Cell Ovarian Cancer. Clin Cancer Res 2020; 26:3397-3407. [PMID: 32060098 PMCID: PMC7334080 DOI: 10.1158/1078-0432.ccr-19-2786] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 01/04/2020] [Accepted: 02/10/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE Clear cell ovarian carcinoma (CCOC) is an aggressive disease that often demonstrates resistance to standard chemotherapies. Approximately 25% of patients with CCOC show a strong APOBEC mutation signature. Here, we determine which APOBEC3 enzymes are expressed in CCOC, establish clinical correlates, and identify a new biomarker for detection and intervention. EXPERIMENTAL DESIGNS APOBEC3 expression was analyzed by IHC and qRT-PCR in a pilot set of CCOC specimens (n = 9 tumors). The IHC analysis of APOBEC3B was extended to a larger cohort to identify clinical correlates (n = 48). Dose-response experiments with platinum-based drugs in CCOC cell lines and carboplatin treatment of patient-derived xenografts (PDXs) were done to address mechanistic linkages. RESULTS One DNA deaminase, APOBEC3B, is overexpressed in a formidable subset of CCOC tumors and is low or absent in normal ovarian and fallopian tube epithelial tissues. High APOBEC3B expression associates with improved progression-free survival (P = 0.026) and moderately with overall survival (P = 0.057). Cell-based studies link APOBEC3B activity and subsequent uracil processing to sensitivity to cisplatin and carboplatin. PDX studies extend this mechanistic relationship to CCOC tissues. CONCLUSIONS These studies demonstrate that APOBEC3B is overexpressed in a subset of CCOC and, contrary to initial expectations, associated with improved (not worse) clinical outcomes. A likely molecular explanation is that APOBEC3B-induced DNA damage sensitizes cells to additional genotoxic stress by cisplatin. Thus, APOBEC3B is a molecular determinant and a candidate predictive biomarker of the therapeutic response to platinum-based chemotherapy. These findings may have broader translational relevance, as APOBEC3B is overexpressed in many different cancer types.
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Affiliation(s)
- Artur A Serebrenik
- Department of Biochemistry, Molecular Biology and Biophysics, College of Biological Sciences, University of Minnesota, Minneapolis, Minnesota
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
- Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Prokopios P Argyris
- Department of Biochemistry, Molecular Biology and Biophysics, College of Biological Sciences, University of Minnesota, Minneapolis, Minnesota
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
- Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota
- Division of Oral and Maxillofacial Pathology, School of Dentistry, University of Minnesota, Minneapolis, Minnesota
| | - Matthew C Jarvis
- Department of Biochemistry, Molecular Biology and Biophysics, College of Biological Sciences, University of Minnesota, Minneapolis, Minnesota
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
- Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota
| | - William L Brown
- Department of Biochemistry, Molecular Biology and Biophysics, College of Biological Sciences, University of Minnesota, Minneapolis, Minnesota
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
- Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota
| | - Martina Bazzaro
- Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, Minnesota
| | - Rachel I Vogel
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, Minnesota
| | - Britt K Erickson
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Department of Obstetrics, Gynecology and Women's Health, University of Minnesota, Minneapolis, Minnesota
| | - Sun-Hee Lee
- Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - Krista M Goergen
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Matthew J Maurer
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Ethan P Heinzen
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Ann L Oberg
- Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota
| | - Yajue Huang
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Xiaonan Hou
- Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | - S John Weroha
- Department of Oncology, Mayo Clinic, Rochester, Minnesota
| | | | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, College of Biological Sciences, University of Minnesota, Minneapolis, Minnesota.
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota
- Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota
- Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota
- Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota
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23
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Phannasil P, Roytrakul S, Phaonakrop N, Kupradinun P, Budda S, Butryee C, Akekawatchai C, Tuntipopipat S. Protein expression profiles that underpin the preventive and therapeutic potential of Moringa oleifera Lam against azoxymethane and dextran sodium sulfate-induced mouse colon carcinogenesis. Oncol Lett 2020; 20:1792-1802. [PMID: 32724422 PMCID: PMC7377166 DOI: 10.3892/ol.2020.11730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2019] [Accepted: 04/01/2020] [Indexed: 12/11/2022] Open
Abstract
Previous studies in a mouse model have indicated the anticancer potential of boiled Moringa oleifera pod (bMO)-supplemented diets; however, its molecular mechanisms are still unclear. Therefore, the present study aimed to explore the protein expression profiles responsible for the suppressive effect of bMO supplementation on azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced mouse colon carcinogenesis. Analysis by gel electrophoresis and liquid chromatography-tandem mass spectrophotometry demonstrated that there were 125 proteins that were differentially expressed in mouse colon tissues between 14 experimental groups of mice. The differentially expressed proteins are involved in various biological processes, such as signal transduction, metabolism, transcription and translation. Venn diagram analysis of the differentially expressed proteins was performed in six selected mouse groups, including negative control, positive control mice induced by AOM/DSS, the AOM/DSS groups receiving preventive or therapeutic bMO diets and their bMO-supplemented control groups. This analysis identified 7 proteins; 60S acidic ribosomal protein P1 (Rplp1), fragile X mental retardation, cystatin 9, round spermatids protein, zinc finger protein 638, protein phosphatase 2C (Ppm1g) and unnamed protein product as being potentially associated with the preventive and therapeutic effects of bMO in AOM/DSS-induced mouse colon cancer. Analysis based on the search tool for interactions of chemicals (STITCH) database predicted that Rplp1 interacted with the apoptotic and inflammatory pathways, whereas Ppm1g was associated only with inflammatory networks. This proteomic analysis revealed candidate proteins that are responsible for the effects of bMO supplementation, potentially by regulating apoptotic and inflammatory signaling networks in colorectal cancer prevention and therapy.
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Affiliation(s)
- Phatchariya Phannasil
- Thalassemia Research Center, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Sittiruk Roytrakul
- Funtional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand
| | - Narumon Phaonakrop
- Funtional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathumthani 12120, Thailand
| | - Piengchai Kupradinun
- Section of Animal Laboratory, Research Division, National Cancer Institute, Bangkok 10400, Thailand
| | - Sirintip Budda
- Food Cluster, Institute of Nutrition, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Chaniphun Butryee
- Food Cluster, Institute of Nutrition, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Chareeporn Akekawatchai
- Department of Medical Technology, Faculty of Allied Health Sciences, Thammasat University, Pathumthani 12121, Thailand
| | - Siriporn Tuntipopipat
- Food Cluster, Institute of Nutrition, Mahidol University, Nakhon Pathom 73170, Thailand
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Hasler D, Meister G, Fischer U. Stabilize and connect: the role of LARP7 in nuclear non-coding RNA metabolism. RNA Biol 2020; 18:290-303. [PMID: 32401147 DOI: 10.1080/15476286.2020.1767952] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
La and La-related proteins (LARPs) are characterized by a common RNA interaction platform termed the La module. This structural hallmark allows LARPs to pervade various aspects of RNA biology. The metazoan LARP7 protein binds to the 7SK RNA as part of a 7SK small nuclear ribonucleoprotein (7SK snRNP), which inhibits the transcriptional activity of RNA polymerase II (Pol II). Additionally, recent findings revealed unanticipated roles of LARP7 in the assembly of other RNPs, as well as in the modification, processing and cellular transport of RNA molecules. Reduced levels of functional LARP7 have been linked to cancer and Alazami syndrome, two seemingly unrelated human diseases characterized either by hyperproliferation or growth retardation. Here, we review the intricate regulatory networks centered on LARP7 and assess how malfunction of these networks may relate to the etiology of LARP7-linked diseases.
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Affiliation(s)
- Daniele Hasler
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, Regensburg, Germany
| | - Gunter Meister
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, Regensburg, Germany
| | - Utz Fischer
- Department of Biochemistry, Theodor Boveri-Institute, University of Würzburg, Würzburg, Germany
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25
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Shukla A, Ramirez NGP, D’Orso I. HIV-1 Proviral Transcription and Latency in the New Era. Viruses 2020; 12:v12050555. [PMID: 32443452 PMCID: PMC7291205 DOI: 10.3390/v12050555] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/06/2020] [Accepted: 05/12/2020] [Indexed: 12/11/2022] Open
Abstract
Three decades of extensive work in the HIV field have revealed key viral and host cell factors controlling proviral transcription. Various models of transcriptional regulation have emerged based on the collective information from in vitro assays and work in both immortalized and primary cell-based models. Here, we provide a recount of the past and current literature, highlight key regulatory aspects, and further describe potential limitations of previous studies. We particularly delve into critical steps of HIV gene expression including the role of the integration site, nucleosome positioning and epigenomics, and the transition from initiation to pausing and pause release. We also discuss open questions in the field concerning the generality of previous regulatory models to the control of HIV transcription in patients under suppressive therapy, including the role of the heterogeneous integration landscape, clonal expansion, and bottlenecks to eradicate viral persistence. Finally, we propose that building upon previous discoveries and improved or yet-to-be discovered technologies will unravel molecular mechanisms of latency establishment and reactivation in a “new era”.
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26
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McCann JL, Klein MM, Leland EM, Law EK, Brown WL, Salamango DJ, Harris RS. The DNA deaminase APOBEC3B interacts with the cell-cycle protein CDK4 and disrupts CDK4-mediated nuclear import of Cyclin D1. J Biol Chem 2019; 294:12099-12111. [PMID: 31217276 PMCID: PMC6690700 DOI: 10.1074/jbc.ra119.008443] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 05/27/2019] [Indexed: 12/13/2022] Open
Abstract
Apolipoprotein B mRNA editing enzyme catalytic subunit-like protein 3B (APOBEC3B or A3B), as other APOBEC3 members, is a single-stranded (ss)DNA cytosine deaminase with antiviral activity. A3B is also overexpressed in multiple tumor types, such as carcinomas of the bladder, cervix, lung, head/neck, and breast. A3B generates both dispersed and clustered C-to-T and C-to-G mutations in intrinsically preferred trinucleotide motifs (TCA/TCG/TCT). A3B-catalyzed mutations are likely to promote tumor evolution and cancer progression and, as such, are associated with poor clinical outcomes. However, little is known about cellular processes that regulate A3B. Here, we used a proteomics approach involving affinity purification coupled to MS with human 293T cells to identify cellular proteins that interact with A3B. This approach revealed a specific interaction with cyclin-dependent kinase 4 (CDK4). We validated and mapped this interaction by co-immunoprecipitation experiments. Functional studies and immunofluorescence microscopy experiments in multiple cell lines revealed that A3B is not a substrate for CDK4-Cyclin D1 phosphorylation nor is its deaminase activity modulated. Instead, we found that A3B is capable of disrupting the CDK4-dependent nuclear import of Cyclin D1. We propose that this interaction may favor a more potent antiviral response and simultaneously facilitate cancer mutagenesis.
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Affiliation(s)
- Jennifer L McCann
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455; Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455; Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455
| | - Madeline M Klein
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Evelyn M Leland
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455
| | - Emily K Law
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455; Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455; Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455; Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota 55455
| | - William L Brown
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455; Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455; Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455
| | - Daniel J Salamango
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455; Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455; Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455.
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455; Institute for Molecular Virology, University of Minnesota, Minneapolis, Minnesota 55455; Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455; Center for Genome Engineering, University of Minnesota, Minneapolis, Minnesota 55455; Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota 55455.
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27
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Shelton SB, Shah NM, Abell NS, Devanathan SK, Mercado M, Xhemalçe B. Crosstalk between the RNA Methylation and Histone-Binding Activities of MePCE Regulates P-TEFb Activation on Chromatin. Cell Rep 2019; 22:1374-1383. [PMID: 29425494 DOI: 10.1016/j.celrep.2018.01.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 12/14/2017] [Accepted: 01/10/2018] [Indexed: 10/18/2022] Open
Abstract
RNAP II switching from the paused to the productive transcription elongation state is a pivotal regulatory step that requires specific phosphorylations catalyzed by the P-TEFb kinase. Nucleosolic P-TEFb activity is inhibited by its interaction with the ribonuclear protein complex built around the 7SK small nuclear RNA (7SK snRNP). MePCE is the RNA methyltransferase that methylates and stabilizes 7SK in the nucleosol. Here, we report that MePCE also binds chromatin through the histone H4 tail to serve as a P-TEFb activator at specific genes important for cellular identity. Notably, this histone binding abolishes MePCE's RNA methyltransferase activity toward 7SK, which explains why MePCE-bound P-TEFb on chromatin may not be associated with the full 7SK snRNP and is competent for RNAP II activation. Overall, our results suggest that crosstalk between the histone-binding and RNA methylation activities of MePCE regulates P-TEFb activation on chromatin in a 7SK- and Brd4-independent manner.
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Affiliation(s)
- Samantha B Shelton
- Department of Molecular Biosciences, 2500 Speedway, Austin, TX 78712, USA
| | - Nakul M Shah
- Department of Molecular Biosciences, 2500 Speedway, Austin, TX 78712, USA
| | - Nathan S Abell
- Department of Molecular Biosciences, 2500 Speedway, Austin, TX 78712, USA; Department of Genetics, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305-5324, USA
| | | | - Marvin Mercado
- Department of Molecular Biosciences, 2500 Speedway, Austin, TX 78712, USA
| | - Blerta Xhemalçe
- Department of Molecular Biosciences, 2500 Speedway, Austin, TX 78712, USA.
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28
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Chavali SS, Bonn-Breach R, Wedekind JE. Face-time with TAR: Portraits of an HIV-1 RNA with diverse modes of effector recognition relevant for drug discovery. J Biol Chem 2019; 294:9326-9341. [PMID: 31080171 DOI: 10.1074/jbc.rev119.006860] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Small molecules and short peptides that potently and selectively bind RNA are rare, making the molecular structures of these complexes highly exceptional. Accordingly, several recent investigations have provided unprecedented structural insights into how peptides and proteins recognize the HIV-1 transactivation response (TAR) element, a 59-nucleotide-long, noncoding RNA segment in the 5' long terminal repeat region of viral transcripts. Here, we offer an integrated perspective on these advances by describing earlier progress on TAR binding to small molecules, and by drawing parallels to recent successes in the identification of compounds that target the hepatitis C virus internal ribosome entry site (IRES) and the flavin-mononucleotide riboswitch. We relate this work to recent progress that pinpoints specific determinants of TAR recognition by: (i) viral Tat proteins, (ii) an innovative lab-evolved TAR-binding protein, and (iii) an ultrahigh-affinity cyclic peptide. New structural details are used to model the TAR-Tat-super-elongation complex (SEC) that is essential for efficient viral transcription and represents a focal point for antiviral drug design. A key prediction is that the Tat transactivation domain makes modest contacts with the TAR apical loop, whereas its arginine-rich motif spans the entire length of the TAR major groove. This expansive interface has significant implications for drug discovery and design, and it further suggests that future lab-evolved proteins could be deployed to discover steric restriction points that block Tat-mediated recruitment of the host SEC to HIV-1 TAR.
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Affiliation(s)
- Sai Shashank Chavali
- From the Department of Biochemistry and Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Rachel Bonn-Breach
- From the Department of Biochemistry and Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
| | - Joseph E Wedekind
- From the Department of Biochemistry and Biophysics, Center for RNA Biology, and Center for AIDS Research, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
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29
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Morton EL, Forst CV, Zheng Y, DePaula-Silva AB, Ramirez NGP, Planelles V, D'Orso I. Transcriptional Circuit Fragility Influences HIV Proviral Fate. Cell Rep 2019; 27:154-171.e9. [PMID: 30943398 PMCID: PMC6461408 DOI: 10.1016/j.celrep.2019.03.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/14/2018] [Accepted: 02/28/2019] [Indexed: 01/12/2023] Open
Abstract
Transcriptional circuit architectures in several organisms have been evolutionarily selected to dictate precise given responses. Unlike these cellular systems, HIV is regulated through a complex circuit composed of two successive phases (host and viral), which create a positive feedback loop facilitating viral replication. However, it has long remained unclear whether both phases operate identically and to what extent the host phase influences the entire circuit. Here, we report that, although the host phase is regulated by a checkpoint whereby KAP1 mediates transcription activation, the virus evolved a minimalist system bypassing KAP1. Given the complex circuit's architecture, cell-to-cell KAP1 fluctuations impart heterogeneity in the host transcriptional responses, thus affecting the feedback loop. Mathematical modeling of a complete circuit reveals how these oscillations ultimately influence homogeneous reactivation potential of a latent virus. Thus, although HIV drives molecular innovation to fuel robust gene activation, it experiences transcriptional fragility, thereby influencing viral fate and cure efforts.
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Affiliation(s)
- Emily L Morton
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Christian V Forst
- Department of Genetics and Genomic Sciences, Icahn Institute for Data Science and Genomic Technology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Yue Zheng
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Ana B DePaula-Silva
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Nora-Guadalupe P Ramirez
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vicente Planelles
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Iván D'Orso
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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30
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Bidaux G, Le Nézet C, Pisfil MG, Henry M, Furlan A, Bensaude O, Vandenbunder B, Héliot L. FRET Image Correlation Spectroscopy Reveals RNAPII-Independent P-TEFb Recruitment on Chromatin. Biophys J 2019; 114:522-533. [PMID: 29414698 DOI: 10.1016/j.bpj.2017.11.3783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 11/24/2017] [Accepted: 11/28/2017] [Indexed: 12/15/2022] Open
Abstract
Biochemical studies have revealed that the RNA Polymerase II (RNAPII) pause release is triggered by phosphorylation of the transcription machinery by the positive transcription elongation factor b (P-TEFb). However, there are no direct report that P-TEFb and RNA polymerase II interact in single living cells and the biophysical mechanisms mediating this association are still unclear. Förster resonance energy transfer (FRET) detects molecular interactions at the subcellular level. Time domain fluorescence lifetime imaging provides an accurate quantification of FRET efficiency, EFRET, because it is fluorochrome concentration-independent and insensitive to fluorescence bleed-through. However, the way FRET signal is usually analyzed does not provide information about the areas where protein-protein interactions take place. In this work, we developed a method, dubbed FRET image correlation spectroscopy (FICS), which relied on FRET fluorescence lifetime imaging image acquisition and image correlation spectroscopy of EFRET clusters to quantify the spatial distribution of interaction clusters in the nucleus. The combination of high content FRET microscopy with batch image analysis allowed a robust statistical analysis. By applying FICS, we characterized the area and density of interaction clusters between P-TEFb and RNAPII or histone H2A in single living cells. The FICS method applied to cells expressing genetically engineered mutated proteins confirmed that the histidine-rich domain of P-TEFb is required for its interaction with RNAPII. Furthermore, it demonstrated that P-TEFb was also located in close vicinity to histone H2A, independently of its interactions with RNAPII. These results support the hypothesis that P-TEFb dynamics on chromatin regulate its recruitment on RNAPII.
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Affiliation(s)
- Gabriel Bidaux
- CNRS UMR 8523, Laboratoire de Physique des Lasers, Atomes et Molécules, University Lille, Lille, France.
| | - Corentin Le Nézet
- CNRS UMR 8523, Laboratoire de Physique des Lasers, Atomes et Molécules, University Lille, Lille, France
| | - Mariano Gonzalez Pisfil
- CNRS UMR 8523, Laboratoire de Physique des Lasers, Atomes et Molécules, University Lille, Lille, France
| | - Mélanie Henry
- CNRS UMR 8523, Laboratoire de Physique des Lasers, Atomes et Molécules, University Lille, Lille, France
| | - Alessandro Furlan
- CNRS UMR 8523, Laboratoire de Physique des Lasers, Atomes et Molécules, University Lille, Lille, France
| | - Oliver Bensaude
- S-2 Génomique Fonctionnelle, IBENS, CNRS UMR 8197, INSERM U1024, Ecole Normale Supérieure, Paris, France
| | - Bernard Vandenbunder
- CNRS UMR 8523, Laboratoire de Physique des Lasers, Atomes et Molécules, University Lille, Lille, France
| | - Laurent Héliot
- CNRS UMR 8523, Laboratoire de Physique des Lasers, Atomes et Molécules, University Lille, Lille, France.
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31
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Lampasona AA, Czaplinski K. Hnrnpab regulates neural cell motility through transcription of Eps8. RNA (NEW YORK, N.Y.) 2019; 25:45-59. [PMID: 30314980 PMCID: PMC6298563 DOI: 10.1261/rna.067413.118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Accepted: 10/01/2018] [Indexed: 05/05/2023]
Abstract
Cell migration requires a complicated network of structural and regulatory proteins. Changes in cellular motility can impact migration as a result of cell-type or developmental stage regulated expression of critical motility genes. Hnrnpab is a conserved RNA-binding protein found as two isoforms produced by alternative splicing. Its expression is enriched in the subventricular zone (SVZ) and the rostral migratory stream within the brain, suggesting possible support of the migration of neural progenitor cells in this region. Here we show that the migration of cells from the SVZ of developing Hnrnpab-/- mouse brains is impaired. An RNA-seq analysis to identify Hnrnpab-dependent cell motility genes led us to Eps8, and in agreement with the change in cell motility, we show that Eps8 is decreased in Hnrnpab-/- SVZ tissue. We scrutinized the motility of Hnrnpab-/- cells and confirmed that the decreases in both cell motility and Eps8 are restored by ectopically coexpressing both alternatively spliced Hnrnpab isoforms, therefore these variants are surprisingly nonredundant for cell motility. Our results support a model where both Hnrnpab isoforms work in concert to regulate Eps8 transcription in the mouse SVZ to promote the normal migration of neural cells during CNS development.
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Affiliation(s)
- Alexa A Lampasona
- Program in Molecular and Cellular Pharmacology, Stony Brook University, Stony Brook, New York 11749, USA
- Centers for Molecular Medicine, Stony Brook University, Stony Brook, New York 11749, USA
| | - Kevin Czaplinski
- Centers for Molecular Medicine, Stony Brook University, Stony Brook, New York 11749, USA
- Department of Anesthesiology, Stony Brook University, Stony Brook, New York 11749, USA
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32
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Abstract
Studies of RNA Polymerase II (Pol II) transcription of the HIV-1 genome are of clinical interest, as the insight gained may lead to strategies to selectively reactivate latent viruses in patients in whom viral replication is suppressed by antiviral drugs. Such a targeted reactivation may contribute to a functional cure of infection. This review discusses five Cyclin-dependent kinases - CDK7, CDK9, CDK11, CDK2, and CDK8 - involved in transcription and processing of HIV-1 RNA. CDK7 is required for Pol II promoter clearance of reactivated viruses; CDK7 also functions as an activating kinase for CDK9 when resting CD4+ T cells harboring latent HIV-1 are activated. CDK9 is targeted by the viral Tat protein and is essential for productive Pol II elongation of the HIV-1 genome. CDK11 is associated with the TREX/THOC complex and it functions in the 3' end processing and polyadenylation of HIV-1 transcripts. CDK2 phosphorylates Tat and CDK9 and this stimulates Tat activation of Pol II transcription. CDK8 may stimulate Pol II transcription of the HIV-1 genome through co-recruitment with NF-κB to the viral promoter. Some notable open questions are discussed concerning the roles of these CDKs in HIV-1 replication and viral latency.
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Affiliation(s)
- Andrew P Rice
- a Department of Molecular Virology and Microbiology , Baylor College of Medicine , Houston , TX , USA
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33
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Abstract
Cyclin-dependent kinase 9 (CDK9) is critical for RNA Polymerase II (Pol II) transcription initiation, elongation, and termination in several key biological processes including development, differentiation, and cell fate responses. A broad range of diseases are characterized by CDK9 malfunction, illustrating its importance in maintaining transcriptional homeostasis in basal- and signal-regulated conditions. Here we provide a historical recount of CDK9 discovery and the current models suggesting CDK9 is a central hub necessary for proper execution of different steps in the transcription cycle. Finally, we discuss the current therapeutic strategies to treat CDK9 malfunction in several disease states. Abbreviations: CDK: Cyclin-dependent kinase; Pol II: RNA Polymerase II; PIC: Pre-initiation Complex; TFIIH: Transcription Factor-II H; snoRNA: small nucleolar RNA; CycT: CyclinT1/T2; P-TEFb: Positive Transcription Elongation Factor Complex; snRNP: small nuclear ribonucleo-protein; HEXIM: Hexamethylene Bis-acetamide-inducible Protein 1/2; LARP7: La-related Protein 7; MePCE: Methylphosphate Capping Enzyme; HIV: human immunodeficiency virus; TAT: trans-activator of transcription; TAR: Trans-activation response element; Hsp70: Heat Shock Protein 70; Hsp90/Cdc37: Hsp90- Hsp90 co-chaperone Cdc37; DSIF: DRB Sensitivity Inducing Factor; NELF: Negative Elongation Factor; CPSF: cleavage and polyadenylation-specific factor; CSTF: cleavage-stimulatory factor; eRNA: enhancer RNA; BRD4: Bromodomain-containing protein 4; JMJD6: Jumonji C-domain-containing protein 6; SEC: Super Elongation Complex; ELL: eleven-nineteen Lys-rich leukemia; ENL: eleven-nineteen leukemia; MLL: mixed lineage leukemia; BEC: BRD4-containing Elongation Complex; SEC-L2/L3: SEC-like complexes; KAP1: Kruppel-associated box-protein 1; KEC: KAP1-7SK Elongation Complex; DRB: Dichloro-1-ß-D-Ribofuranosylbenzimidazole; H2Bub1: H2B mono-ubiquitination; KM: KM05382; PP1: Protein Phosphatase 1; CDK9i: CDK9 inhibitor; SHAPE: Selective 2'-hydroxyl acylation analyzed by primer extension; TE: Typical enhancer; SE : Super enhancer.
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Affiliation(s)
- Curtis W Bacon
- a Biological Chemistry Graduate Program , The University of Texas Southwestern Medical Center , Dallas, TX , USA
| | - Iván D'Orso
- b Department of Microbiology , The University of Texas Southwestern Medical Center , Dallas , TX , USA
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34
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Wang M, Yang W, Chen Y, Wang J, Tan J, Qiao W. Cellular RelB interacts with the transactivator Tat and enhance HIV-1 expression. Retrovirology 2018; 15:65. [PMID: 30241541 PMCID: PMC6150996 DOI: 10.1186/s12977-018-0447-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 09/15/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Human immunodeficiency virus type 1 (HIV-1) Tat protein plays an essential role in HIV-1 gene transcription. Tat transactivates HIV-1 long terminal repeat (LTR)-directed gene expression through direct interactions with the transactivation-responsive region (TAR) element and other cis elements in the LTR. The TAR-independent Tat-mediated LTR transactivation is modulated by several host factors, but the mechanism is not fully understood. RESULTS Here, we report that Tat interacts with the Rel homology domain of RelB through its core region. Furthermore, RelB significantly increases Tat-mediated transcription of the HIV-1 LTR and viral gene expression, which is independent of the TAR. Both Tat and RelB are recruited to the HIV-1 promoter, of which RelB facilitates the recruitment of Tat to the viral LTR. The NF-κB elements are key to the accumulation of Tat and RelB on the LTR. Knockout of RelB reduces the accumulation of RNA polymerase II on the LTR, and decreases HIV-1 gene transcription. Together, our data suggest that RelB contributes to HIV-1 transactivation. CONCLUSIONS Our results demonstrate that RelB interacts with Tat and enhances TAR-independent activation of HIV-1 LTR promoter, which adds new insights into the multi-layered mechanisms of Tat in regulating the gene expression of HIV-1.
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Affiliation(s)
- Meng Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Wei Yang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Yu Chen
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Jian Wang
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Juan Tan
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
| | - Wentao Qiao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
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35
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Pyo J, Ryu J, Kim W, Choi JS, Jeong JW, Kim JE. The Protein Phosphatase PPM1G Destabilizes HIF-1α Expression. Int J Mol Sci 2018; 19:ijms19082297. [PMID: 30081604 PMCID: PMC6121667 DOI: 10.3390/ijms19082297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/23/2018] [Accepted: 08/01/2018] [Indexed: 12/30/2022] Open
Abstract
Hypoxia-inducible factors (HIFs) are key regulators of hypoxic responses, and their stability and transcriptional activity are controlled by several kinases. However, the regulation of HIF by protein phosphatases has not been thoroughly investigated. Here, we found that overexpression of Mg2+/Mn2+-dependent protein phosphatase 1 gamma (PPM1G), one of Ser/Thr protein phosphatases, downregulated protein expression of ectopic HIF-1α under normoxic or acute hypoxic conditions. In addition, the deficiency of PPM1G upregulated protein expression of endogenous HIF-1α under normoxic or acute oxidative stress conditions. PPM1G decreased expression of HIF-1α via the proteasomal pathway. PPM1G-mediated HIF-1α degradation was dependent on prolyl hydroxylase (PHD), but independent of von Hippel-Lindau (VHL). These data suggest that PPM1G is critical for the control of HIF-1α-dependent responses.
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Affiliation(s)
- Jaehyuk Pyo
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Jaewook Ryu
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Wootae Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Jae-Sun Choi
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
| | - Joo-Won Jeong
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
- Department of Anatomy and Neurobiology, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
| | - Ja-Eun Kim
- Department of Biomedical Science, Graduate School, Kyung Hee University, Seoul 02447, Korea.
- Department of Pharmacology, School of Medicine, Kyung Hee University, Seoul 02447, Korea.
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36
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Rice AP. The HIV-1 Tat Protein: Mechanism of Action and Target for HIV-1 Cure Strategies. Curr Pharm Des 2018; 23:4098-4102. [PMID: 28677507 DOI: 10.2174/1381612823666170704130635] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/12/2017] [Accepted: 06/20/2017] [Indexed: 02/07/2023]
Abstract
The general mechanism involved in Tat activation of RNA Polymerase II (RNAP II) elongation of the integrated HIV-1 was elucidated over 20 years ago. This mechanism involves Tat binding to the TAR RNA element that forms at the 5' end of viral transcripts and recruiting a general RNAP II elongation factor termed as PTEFb. This elongation factor consists of CDK9 and Cyclin T1, and when recruited by Tat to TAR RNA, CDK9 was proposed to phosphorylate the carboxyl terminal domain of RNAP II and thereby activate elongation. Research in the past two decades has shown that the mechanism of Tat action is considerably more complicated than this simple model. In metabolically active cells, CDK9 and Cyclin T1 are now known to be largely sequestered in a RNA-protein complex termed the 7SK RNP. CDK9 and Cyclin T1 are released from the 7SK RNP by mechanisms not yet fully elucidated and along with Tat, bind to TAR RNA and orchestrate the assembly of a Super Elongation Complex (SEC) containing several additional proteins. CDK9 in the SEC then phosphorylates multiple substrates in the RNAP II complex to activate elongation. Importantly for therapeutic strategies, CDK9 and Cyclin T1 functions are down-regulated in resting CD4+ T cells that harbor latent HIV-1, and their up-regulation is required for reactivation of latent virus. Current strategies for a functional cure of HIV-1 infection therefore are likely to require development of latency reversal agents that up-regulate CDK9 and Cyclin T1 function in resting CD4+ T cells.
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Affiliation(s)
- Andrew P Rice
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030. United States
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Abstract
BACKGROUND The viral transactivator Tat protein is a key modulator of HIV-1 replication, as it regulates transcriptional elongation from the integrated proviral genome. Tat recruits the human transcription elongation factor b, and other host proteins, such as the super elongation complex, to activate the cellular RNA polymerase II, normally stalled shortly after transcription initiation at the HIV promoter. By means of a complex set of interactions with host cellular factors, Tat determines the fate of viral activity within the infected cell. The virus will either actively replicate to promote dissemination in blood and tissues, or become dormant mostly in memory CD4+ T cells, as part of a small but long-living latent reservoir, the main obstacle for HIV eradication. OBJECTIVE In this review, we summarize recent advances in the understanding of the multi-step mechanism that regulates Tat-mediated HIV-1 transcription and RNA polymerase II release, to promote viral transcription elongation. Early events of the human transcription elongation factor b release from the inhibitory 7SK small nuclear ribonucleoprotein complex and its recruitment to the HIV promoter will be discussed. Specific roles of the super elongation complex subunits during transcription elongation, and insight on recently identified cellular factors and mechanisms regulating HIV latency will be detailed. CONCLUSION Understanding the complexity of HIV transcriptional regulation by host factors may open the door for development of novel strategies to eradicate the resilient latent reservoir.
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Affiliation(s)
- Guillaume Mousseau
- The Scripps Research Institute, Department of Immunology and Microbiology, 130 Scripps Way, Jupiter, FL 33458. United States
| | - Susana T Valente
- The Scripps Research Institute, Department of Immunology and Microbiology, 130 Scripps Way, Jupiter, FL 33458. United States
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Mbonye U, Wang B, Gokulrangan G, Shi W, Yang S, Karn J. Cyclin-dependent kinase 7 (CDK7)-mediated phosphorylation of the CDK9 activation loop promotes P-TEFb assembly with Tat and proviral HIV reactivation. J Biol Chem 2018; 293:10009-10025. [PMID: 29743242 DOI: 10.1074/jbc.ra117.001347] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 04/29/2018] [Indexed: 11/06/2022] Open
Abstract
The HIV trans-activator Tat recruits the host transcription elongation factor P-TEFb to stimulate proviral transcription. Phosphorylation of Thr-186 on the activation loop (T-loop) of cyclin-dependent kinase 9 (CDK9) is essential for its kinase activity and assembly of CDK9 and cyclin T1 (CycT1) to form functional P-TEFb. Phosphorylation of a second highly conserved T-loop site, Ser-175, alters the competitive binding of Tat and the host recruitment factor bromodomain containing 4 (BRD4) to P-TEFb. Here, we investigated the intracellular mechanisms that regulate these key phosphorylation events required for HIV transcription. Molecular dynamics simulations revealed that the CDK9/CycT1 interface is stabilized by intramolecular hydrogen bonding of pThr-186 by an arginine triad and Glu-96 of CycT1. Arginine triad substitutions that disrupted CDK9/CycT1 assembly accumulated Thr-186-dephosphorylated CDK9 associated with the cytoplasmic Hsp90/Cdc37 chaperone. The Hsp90/Cdc37/CDK9 complex was also present in resting T cells, which lack CycT1. Hsp90 inhibition in primary T cells blocked P-TEFb assembly, disrupted Thr-186 phosphorylation, and suppressed proviral reactivation. The selective CDK7 inhibitor THZ1 blocked CDK9 phosphorylation at Ser-175, and in vitro kinase assays confirmed that CDK7 activity is principally responsible for Ser-175 phosphorylation. Mutation of Ser-175 to Lys had no effect on CDK9 kinase activity or P-TEFb assembly but strongly suppressed both HIV expression and BRD4 binding. We conclude that the transfer of CDK9 from the Hsp90/Cdc37 complex induced by Thr-186 phosphorylation is a key step in P-TEFb biogenesis. Furthermore, we demonstrate that CDK7-mediated Ser-175 phosphorylation is a downstream nuclear event essential for facilitating CDK9 T-loop interactions with Tat.
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Affiliation(s)
- Uri Mbonye
- From the Department of Molecular Biology and Microbiology and
| | - Benlian Wang
- the Center for Proteomics and Bioinformatics and Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Giridharan Gokulrangan
- the Center for Proteomics and Bioinformatics and Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Wuxian Shi
- the Center for Proteomics and Bioinformatics and Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Sichun Yang
- the Center for Proteomics and Bioinformatics and Department of Nutrition, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Jonathan Karn
- From the Department of Molecular Biology and Microbiology and
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Abstract
Hexim1 acts as a tumor suppressor and is involved in the regulation of innate immunity. It was initially described as a non-coding RNA-dependent regulator of transcription. Here, we detail how 7SK RNA binds to Hexim1 and turns it into an inhibitor of the positive transcription elongation factor (P-TEFb). In addition to its action on P-TEFb, it plays a role in a variety of different mechanisms: it controls the stability of transcription factor components and assists binding of transcription factors to their targets.
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Affiliation(s)
- Annemieke A Michels
- a IBENS , Ecole Normale Supérieure UMR CNRS 8107, UA INSERM 1024 , 46 rue d'Ulm Paris Cedex France
| | - Olivier Bensaude
- a IBENS , Ecole Normale Supérieure UMR CNRS 8107, UA INSERM 1024 , 46 rue d'Ulm Paris Cedex France
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40
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Li Y, Liu M, Chen LF, Chen R. P-TEFb: Finding its ways to release promoter-proximally paused RNA polymerase II. Transcription 2018; 9:88-94. [PMID: 28102758 PMCID: PMC5834220 DOI: 10.1080/21541264.2017.1281864] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/09/2017] [Accepted: 01/09/2017] [Indexed: 12/26/2022] Open
Abstract
The release of a paused Pol II depends on the recruitment of P-TEFb. Recent studies showed that both active P-TEFb and inactive P-TEFb (7SK snRNP) can be recruited to the promoter regions of global genes by different mechanisms. Here, we summarize the recent advances on these distinct recruitment mechanisms.
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Affiliation(s)
- You Li
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Min Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
| | - Lin-Feng Chen
- Department of Biochemistry, College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Ruichuan Chen
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, China
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Ne E, Palstra RJ, Mahmoudi T. Transcription: Insights From the HIV-1 Promoter. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2018; 335:191-243. [DOI: 10.1016/bs.ircmb.2017.07.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Sciuto MR, Warnken U, Schnölzer M, Valvo C, Brunetto L, Boe A, Biffoni M, Krammer PH, De Maria R, Haas TL. Two-Step Coimmunoprecipitation (TIP) Enables Efficient and Highly Selective Isolation of Native Protein Complexes. Mol Cell Proteomics 2017; 17:993-1009. [PMID: 29217617 DOI: 10.1074/mcp.o116.065920] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 11/22/2017] [Indexed: 11/06/2022] Open
Abstract
Coimmunoprecipitation (co-IP) is one of the most frequently used techniques to study protein-protein (PPIs) or protein-nucleic acid interactions (PNIs). However, the presence of coprecipitated contaminants is a well-recognized issue associated with single-step co-IPs. To overcome this limitation, we developed the two-step co-IP (TIP) strategy that enables sequential coimmunoprecipitations of endogenous protein complexes. TIP can be performed with a broad range of mono- and polyclonal antibodies targeting a single protein or different components of a given complex. TIP results in a highly selective enrichment of protein complexes and thus outperforms single-step co-IPs for downstream applications such as mass spectrometry for the identification of PPIs and quantitative PCR for the analysis of PNIs. We benchmarked TIP for the identification of CD95/FAS-interacting proteins in primary human CD4+ T cells, which recapitulated all major known interactors, but also enabled the proteomics discovery of PPM1G and IPO7 as new interaction partners. For its feasibility and high performance, we propose TIP as an advanced tool for the isolation of highly purified protein-protein and protein-nucleic acid complexes under native expression conditions.
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Affiliation(s)
- Maria Rita Sciuto
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy;
| | - Uwe Warnken
- §Functional Proteome Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Martina Schnölzer
- §Functional Proteome Analysis, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Cecilia Valvo
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy.,¶Institute of General Pathology, Catholic University and Gemelli Polyclinic, Largo F. Vito 1, 00168, Rome, Italy
| | - Lidia Brunetto
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Alessandra Boe
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Mauro Biffoni
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy
| | - Peter H Krammer
- ‖Department of Tumor Immunology, German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120, Heidelberg, Germany
| | - Ruggero De Maria
- ¶Institute of General Pathology, Catholic University and Gemelli Polyclinic, Largo F. Vito 1, 00168, Rome, Italy
| | - Tobias L Haas
- From the ‡Department of Hematology and Oncology, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161, Rome, Italy; .,¶Institute of General Pathology, Catholic University and Gemelli Polyclinic, Largo F. Vito 1, 00168, Rome, Italy
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Liu X, Gao Y, Ye H, Gerrin S, Ma F, Wu Y, Zhang T, Russo J, Cai C, Yuan X, Liu J, Chen S, Balk SP. Positive feedback loop mediated by protein phosphatase 1α mobilization of P-TEFb and basal CDK1 drives androgen receptor in prostate cancer. Nucleic Acids Res 2017; 45:3738-3751. [PMID: 28062857 PMCID: PMC5397168 DOI: 10.1093/nar/gkw1291] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 12/25/2016] [Indexed: 01/05/2023] Open
Abstract
P-TEFb (CDK9/cyclin T) plays a central role in androgen receptor (AR)-mediated transactivation by phosphorylating both RNA polymerase 2 complex proteins and AR at S81. CDK9 dephosphorylation mobilizes P-TEFb from an inhibitory 7SK ribonucleoprotein complex, but mechanisms targeting phosphatases to P-TEFb are unclear. We show that AR recruits protein phosphatase 1α (PP1α), resulting in P-TEFb mobilization and CDK9-mediated AR S81 phosphorylation. This increased pS81 enhances p300 recruitment, histone acetylation, BRD4 binding and subsequent further recruitment of P-TEFb, generating a positive feedback loop that sustains transcription. AR S81 is also phosphorylated by CDK1, and blocking basal CDK1-mediated S81 phosphorylation markedly suppresses AR activity and initiation of this positive feedback loop. Finally, androgen-independent AR activity in castration-resistant prostate cancer (CRPC) cells is driven by increased CDK1-mediated S81 phosphorylation. Collectively these findings reveal a mechanism involving PP1α, CDK9 and CDK1 that is used by AR to initiate and sustain P-TEFb activity, which may be exploited to drive AR in CRPC.
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Affiliation(s)
- Xiaming Liu
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Yanfei Gao
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - HuiHui Ye
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Sean Gerrin
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Fen Ma
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Yiming Wu
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Tengfei Zhang
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Joshua Russo
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Changmeng Cai
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Xin Yuan
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Jihong Liu
- Department of Urology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Shaoyong Chen
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Steven P Balk
- Hematology-Oncology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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Egloff S, Studniarek C, Kiss T. 7SK small nuclear RNA, a multifunctional transcriptional regulatory RNA with gene-specific features. Transcription 2017; 9:95-101. [PMID: 28820318 DOI: 10.1080/21541264.2017.1344346] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The 7SK small nuclear RNA is a multifunctional transcriptional regulatory RNA that controls the nuclear activity of the positive transcription elongation factor b (P-TEFb), specifically targets P-TEFb to the promoter regions of selected protein-coding genes and promotes transcription of RNA polymerase II-specific spliceosomal small nuclear RNA genes.
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Affiliation(s)
- Sylvain Egloff
- a Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, Centre de Biologie Intégrative, Université Paul Sabatier , Toulouse , France
| | - Cécilia Studniarek
- a Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, Centre de Biologie Intégrative, Université Paul Sabatier , Toulouse , France
| | - Tamás Kiss
- a Laboratoire de Biologie Moléculaire Eucaryote du CNRS, UMR5099, Centre de Biologie Intégrative, Université Paul Sabatier , Toulouse , France.,b Biological Research Centre , Hungarian Academy of Sciences , Szeged , Hungary
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45
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Kropp J, Carrillo JA, Namous H, Daniels A, Salih SM, Song J, Khatib H. Male fertility status is associated with DNA methylation signatures in sperm and transcriptomic profiles of bovine preimplantation embryos. BMC Genomics 2017; 18:280. [PMID: 28381255 PMCID: PMC5382486 DOI: 10.1186/s12864-017-3673-y] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 03/31/2017] [Indexed: 11/12/2022] Open
Abstract
Background Infertility in dairy cattle is a concern where reduced fertilization rates and high embryonic loss are contributing factors. Studies of the paternal contribution to reproductive performance are limited. However, recent discoveries have shown that, in addition to DNA, sperm delivers transcription factors and epigenetic components that are required for fertilization and proper embryonic development. Hence, characterization of the paternal contribution at the time of fertilization is warranted. We hypothesized that sire fertility is associated with differences in DNA methylation patterns in sperm and that the embryonic transcriptomic profiles are influenced by the fertility status of the bull. Embryos were generated in vitro by fertilization with either a high or low fertility Holstein bull. Blastocysts derived from each high and low fertility bulls were evaluated for morphology, development, and transcriptomic analysis using RNA-Sequencing. Additionally, DNA methylation signatures of sperm from high and low fertility sires were characterized by performing whole-genome DNA methylation binding domain sequencing. Results Embryo morphology and developmental capacity did not differ between embryos generated from either a high or low fertility bull. However, RNA-Sequencing revealed 98 genes to be differentially expressed at a false discovery rate < 1%. A total of 65 genes were upregulated in high fertility bull derived embryos, and 33 genes were upregulated in low fertility derived embryos. Expression of the genes CYCS, EEA1, SLC16A7, MEPCE, and TFB2M was validated in three new pairs of biological replicates of embryos. The role of the differentially expressed gene TFB2M in embryonic development was further assessed through expression knockdown at the zygotic stage, which resulted in decreased development to the blastocyst stage. Assessment of the epigenetic signature of spermatozoa between high and low fertility bulls revealed 76 differentially methylated regions. Conclusions Despite similar morphology and development to the blastocyst stage, preimplantation embryos derived from high and low fertility bulls displayed significant transcriptomic differences. The relationship between the paternal contribution and the embryonic transcriptome is unclear, although differences in methylated regions were identified which could influence the reprogramming of the early embryo. Further characterization of paternal factors delivered to the oocyte could lead to the identification of biomarkers for better selection of sires to improve reproductive efficiency. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3673-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jenna Kropp
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - José A Carrillo
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, 20742, USA
| | - Hadjer Namous
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Alyssa Daniels
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Sana M Salih
- Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, WI, 53792, USA.,Present address: Department of Obstetrics and Gynecology, West Virginia University, Morgantown, WV, 26508, USA
| | - Jiuzhou Song
- Department of Animal and Avian Sciences, University of Maryland, College Park, MD, 20742, USA
| | - Hasan Khatib
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA.
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PJA2 ubiquitinates the HIV-1 Tat protein with atypical chain linkages to activate viral transcription. Sci Rep 2017; 7:45394. [PMID: 28345603 PMCID: PMC5366948 DOI: 10.1038/srep45394] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 02/22/2017] [Indexed: 12/23/2022] Open
Abstract
Transcription complexes that assemble at the HIV-1 promoter efficiently initiate transcription but generate paused RNA polymerase II downstream from the start site. The virally encoded Tat protein hijacks positive transcription elongation factor b (P-TEFb) to phosphorylate and activate this paused polymerase. In addition, Tat undergoes a series of reversible post-translational modifications that regulate distinct steps of the transcription cycle. To identify additional functionally important Tat cofactors, we performed RNAi knockdowns of sixteen previously identified Tat interactors and found that a novel E3 ligase, PJA2, ubiquitinates Tat in a non-degradative manner and specifically regulates the step of HIV transcription elongation. Interestingly, several different lysine residues in Tat can function as ubiquitin acceptor sites, and variable combinations of these lysines support both full transcriptional activity and viral replication. Further, the polyubiquitin chain conjugated to Tat by PJA2 can itself be assembled through variable ubiquitin lysine linkages. Importantly, proper ubiquitin chain assembly by PJA2 requires that Tat first binds its P-TEFb cofactor. These results highlight that both the Tat substrate and ubiquitin modification have plastic site usage, and this plasticity is likely another way in which the virus exploits the host molecular machinery to expand its limited genetic repertoire.
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47
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Ma Z, Fung V, D'Orso I. Tandem Affinity Purification of Protein Complexes from Eukaryotic Cells. J Vis Exp 2017. [PMID: 28190026 DOI: 10.3791/55236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The purification of active protein-protein and protein-nucleic acid complexes is crucial for the characterization of enzymatic activities and de novo identification of novel subunits and post-translational modifications. Bacterial systems allow for the expression and purification of a wide variety of single polypeptides and protein complexes. However, this system does not enable the purification of protein subunits that contain post-translational modifications (e.g., phosphorylation and acetylation), and the identification of novel regulatory subunits that are only present/expressed in the eukaryotic system. Here, we provide a detailed description of a novel, robust, and efficient tandem affinity purification (TAP) method using STREP- and FLAG-tagged proteins that facilitates the purification of protein complexes with transiently or stably expressed epitope-tagged proteins from eukaryotic cells. This protocol can be applied to characterize protein complex functionality, to discover post-translational modifications on complex subunits, and to identify novel regulatory complex components by mass spectrometry. Notably, this TAP method can be applied to study protein complexes formed by eukaryotic or pathogenic (viral and bacterial) components, thus yielding a wide array of downstream experimental opportunities. We propose that researchers working with protein complexes could utilize this approach in many different ways.
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Affiliation(s)
- Zheng Ma
- Department of Microbiology, The University of Texas Southwestern Medical Center
| | - Victor Fung
- Department of Microbiology, The University of Texas Southwestern Medical Center
| | - Iván D'Orso
- Department of Microbiology, The University of Texas Southwestern Medical Center;
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Targeting Chromatin Remodeling in Inflammation and Fibrosis. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2016; 107:1-36. [PMID: 28215221 DOI: 10.1016/bs.apcsb.2016.11.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Mucosal surfaces of the human body are lined by a contiguous epithelial cell surface that forms a barrier to aerosolized pathogens. Specialized pattern recognition receptors detect the presence of viral pathogens and initiate protective host responses by triggering activation of the nuclear factor κB (NFκB)/RelA transcription factor and formation of a complex with the positive transcription elongation factor (P-TEFb)/cyclin-dependent kinase (CDK)9 and Bromodomain-containing protein 4 (BRD4) epigenetic reader. The RelA·BRD4·P-TEFb complex produces acute inflammation by regulating transcriptional elongation, which produces a rapid genomic response by inactive genes maintained in an open chromatin configuration engaged with hypophosphorylated RNA polymerase II. We describe recent studies that have linked prolonged activation of the RelA-BRD4 pathway with the epithelial-mesenchymal transition (EMT) by inducing a core of EMT corepressors, stimulating secretion of growth factors promoting airway fibrosis. The mesenchymal state produces rewiring of the kinome and reprogramming of innate responses toward inflammation. In addition, the core regulator Zinc finger E-box homeodomain 1 (ZEB1) silences the expression of the interferon response factor 1 (IRF1), required for type III IFN expression. This epigenetic silencing is mediated by the Enhancer of Zeste 2 (EZH2) histone methyltransferase. Because of their potential applications in cancer and inflammation, small-molecule inhibitors of NFκB/RelA, CDK9, BRD4, and EZH2 have been the targets of medicinal chemistry efforts. We suggest that disruption of the RelA·BRD4·P-TEFb pathway and EZH2 methyltransferase has important implications for reversing fibrosis and restoring normal mucosal immunity in chronic inflammatory diseases.
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Abstract
INTRODUCTION A number of cyclin-dependent kinases (CDKs) mediate key steps in the HIV-1 replication cycle and therefore have potential to serve as therapeutic targets for HIV-1 infection, especially in HIV-1 cure strategies. Current HIV-1 cure strategies involve the development of small molecules that are able to activate HIV-1 from latent infection, thereby allowing the immune system to recognize and clear infected cells. Areas covered: The role of seven CDK family members in the HIV-1 replication cycle is reviewed, with a focus on CDK9, as the mechanism whereby the viral Tat protein utilizes CDK9 to enhance viral replication is known in considerable detail. Expert opinion: Given the essential roles of CDKs in cellular proliferation and gene expression, small molecules that inhibit CDKs are unlikely to be feasible therapeutics for HIV-1 infection. However, small molecules that activate CDK9 and other select CDKs such as CDK11 have potential to reactivate latent HIV-1 and contribute to a functional cure of infection.
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Affiliation(s)
- Andrew P Rice
- a Department of Molecular Virology and Microbiology , Baylor College of Medicine , Houston , TX USA
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50
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Marban C, Forouzanfar F, Ait-Ammar A, Fahmi F, El Mekdad H, Daouad F, Rohr O, Schwartz C. Targeting the Brain Reservoirs: Toward an HIV Cure. Front Immunol 2016; 7:397. [PMID: 27746784 PMCID: PMC5044677 DOI: 10.3389/fimmu.2016.00397] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 09/20/2016] [Indexed: 12/23/2022] Open
Abstract
One of the top research priorities of the international AIDS society by the action “Towards an HIV Cure” is the purge or the decrease of the pool of all latently infected cells. This strategy is based on reactivation of latently reservoirs (the shock) followed by an intensifying combination antiretroviral therapy (cART) to kill them (the kill). The central nervous system (CNS) has potential latently infected cells, i.e., perivascular macrophages, microglial cells, and astrocytes that will need to be eliminated. However, the CNS has several characteristics that may preclude the achievement of a cure. In this review, we discuss several limitations to the eradication of brain reservoirs and how we could circumvent these limitations by making it efforts in four directions: (i) designing efficient latency-reversal agents for CNS-cell types, (ii) improving cART by targeting HIV transcription, (iii) improving delivery of HIV drugs in the CNS and in the CNS-cell types, and (iv) developing therapeutic immunization. As a prerequisite to these efforts, we also believe that a better comprehension of molecular mechanisms involved in establishment and persistence of HIV latency in brain reservoirs are essential to design new molecules for strategies aiming to achieve a cure for instance the “shock and kill” strategy.
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Affiliation(s)
- Céline Marban
- INSERM UMR 1121 Faculté de Chirurgie Dentaire, Université de Strasbourg , Strasbourg , France
| | | | - Amina Ait-Ammar
- EA7292, DHPI, Université de Strasbourg , Strasbourg , France
| | - Faiza Fahmi
- EA7292, DHPI, Université de Strasbourg , Strasbourg , France
| | - Hala El Mekdad
- EA7292, DHPI, Université de Strasbourg, Strasbourg, France; IUT Louis Pasteur de Schiltigheim, Université de Strasbourg, Schiltigheim, France
| | - Fadoua Daouad
- EA7292, DHPI, Université de Strasbourg , Strasbourg , France
| | - Olivier Rohr
- EA7292, DHPI, Université de Strasbourg, Strasbourg, France; IUT Louis Pasteur de Schiltigheim, Université de Strasbourg, Schiltigheim, France; Institut Universitaire de France, Paris, France
| | - Christian Schwartz
- EA7292, DHPI, Université de Strasbourg, Strasbourg, France; IUT Louis Pasteur de Schiltigheim, Université de Strasbourg, Schiltigheim, France
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