1
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D'Orso I. The HIV-1 Transcriptional Program: From Initiation to Elongation Control. J Mol Biol 2024:168690. [PMID: 38936695 DOI: 10.1016/j.jmb.2024.168690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 06/20/2024] [Accepted: 06/21/2024] [Indexed: 06/29/2024]
Abstract
A large body of work in the last four decades has revealed the key pillars of HIV-1 transcription control at the initiation and elongation steps. Here, I provide a recount of this collective knowledge starting with the genomic elements (DNA and nascent TAR RNA stem-loop) and transcription factors (cellular and the viral transactivator Tat), and later transitioning to the assembly and regulation of transcription initiation and elongation complexes, and the role of chromatin structure. Compelling evidence support a core HIV-1 transcriptional program regulated by the sequential and concerted action of cellular transcription factors and Tat to promote initiation and sustain elongation, highlighting the efficiency of a small virus to take over its host to produce the high levels of transcription required for viral replication. I summarize new advances including the use of CRISPR-Cas9, genetic tools for acute factor depletion, and imaging to study transcriptional dynamics, bursting and the progression through the multiple phases of the transcriptional cycle. Finally, I describe current challenges to future major advances and discuss areas that deserve more attention to both bolster our basic knowledge of the core HIV-1 transcriptional program and open up new therapeutic opportunities.
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Affiliation(s)
- Iván D'Orso
- Department of Microbiology, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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2
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Zhang Z, Xu J, Liu J, Wang J, Lei L. SEC: A core hub during cell fate alteration. FASEB J 2024; 38:e23680. [PMID: 38758186 DOI: 10.1096/fj.202400514r] [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: 03/06/2024] [Revised: 04/18/2024] [Accepted: 05/07/2024] [Indexed: 05/18/2024]
Abstract
Pol II pause release is a rate-limiting step in gene transcription, influencing various cell fate alterations. Numerous proteins orchestrate Pol II pause release, thereby playing pivotal roles in the intricate process of cellular fate modulation. Super elongation complex (SEC), a large assembly comprising diverse protein components, has garnered attention due to its emerging significance in orchestrating physiological and pathological cellular identity changes by regulating the transcription of crucial genes. Consequently, SEC emerges as a noteworthy functional complex capable of modulating cell fate alterations. Therefore, a comprehensive review is warranted to systematically summarize the core roles of SEC in different types of cell fate alterations. This review focuses on elucidating the current understanding of the structural and functional basis of SEC. Additionally, we discuss the intricate regulatory mechanisms governing SEC in various models of cell fate alteration, encompassing both physiological and pathological contexts. Furthermore, leveraging the existing knowledge of SEC, we propose some insightful directions for future research, aiming to enhance our mechanistic and functional comprehension of SEC within the diverse landscape of cell fate alterations.
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Affiliation(s)
- Zhijing Zhang
- College of Life Science, Northeast Agricultural University, Harbin, Heilongjiang Province, China
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang Province, China
| | - Jingyi Xu
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang Province, China
| | - Jiqiang Liu
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang Province, China
| | - Jiaqiang Wang
- College of Life Science, Northeast Agricultural University, Harbin, Heilongjiang Province, China
| | - Lei Lei
- Department of Histology and Embryology, Harbin Medical University, Harbin, Heilongjiang Province, China
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3
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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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4
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Long Q, Xiang M, Xiao L, Wang J, Guan X, Liu J, Liao C. The Biological Significance of AFF4: Promoting Transcription Elongation, Osteogenic Differentiation and Tumor Progression. Comb Chem High Throughput Screen 2024; 27:1403-1412. [PMID: 37815186 DOI: 10.2174/0113862073241079230920082056] [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: 12/20/2022] [Revised: 06/23/2023] [Accepted: 07/27/2023] [Indexed: 10/11/2023]
Abstract
As a member of the AF4/FMR2 (AFF) family, AFF4 is a scaffold protein in the superelongation complex (SEC). In this mini-view, we discuss the role of AFF4 as a transcription elongation factor that mediates HIV activation and replication and stem cell osteogenic differentiation. AFF4 also promotes the progression of head and neck squamous cell carcinoma, leukemia, breast cancer, bladder cancer and other malignant tumors. The biological function of AFF4 is largely achieved through SEC assembly, regulates SRY-box transcription factor 2 (SOX2), MYC, estrogen receptor alpha (ESR1), inhibitor of differentiation 1 (ID1), c-Jun and noncanonical nuclear factor-κB (NF-κB) transcription and combines with fusion in sarcoma (FUS), unique regulatory cyclins (CycT1), or mixed lineage leukemia (MLL). We explore the prospects of using AFF4 as a therapeutic in Acquired immunodeficiency syndrome (AIDS) and malignant tumors and its potential as a stemness regulator.
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Affiliation(s)
- Qian Long
- Department of Orthodontics II, Affiliated Stomatological Hospital of Zunyi Medical University, Zunyi, 563000, China
- Oral Disease Research Key Laboratory of Guizhou Tertiary Institution, School of Stomatology, Zunyi Medical University, Zunyi, 563006, China
| | - Mingli Xiang
- Department of Orthodontics II, Affiliated Stomatological Hospital of Zunyi Medical University, Zunyi, 563000, China
- Oral Disease Research Key Laboratory of Guizhou Tertiary Institution, School of Stomatology, Zunyi Medical University, Zunyi, 563006, China
| | - Linlin Xiao
- Department of Orthodontics II, Affiliated Stomatological Hospital of Zunyi Medical University, Zunyi, 563000, China
- Oral Disease Research Key Laboratory of Guizhou Tertiary Institution, School of Stomatology, Zunyi Medical University, Zunyi, 563006, China
| | - Jiajia Wang
- Department of Orthodontics II, Affiliated Stomatological Hospital of Zunyi Medical University, Zunyi, 563000, China
- Oral Disease Research Key Laboratory of Guizhou Tertiary Institution, School of Stomatology, Zunyi Medical University, Zunyi, 563006, China
| | - Xiaoyan Guan
- Department of Orthodontics II, Affiliated Stomatological Hospital of Zunyi Medical University, Zunyi, 563000, China
- Oral Disease Research Key Laboratory of Guizhou Tertiary Institution, School of Stomatology, Zunyi Medical University, Zunyi, 563006, China
| | - Jianguo Liu
- Department of Orthodontics II, Affiliated Stomatological Hospital of Zunyi Medical University, Zunyi, 563000, China
- Oral Disease Research Key Laboratory of Guizhou Tertiary Institution, School of Stomatology, Zunyi Medical University, Zunyi, 563006, China
| | - Chengcheng Liao
- Department of Orthodontics II, Affiliated Stomatological Hospital of Zunyi Medical University, Zunyi, 563000, China
- Oral Disease Research Key Laboratory of Guizhou Tertiary Institution, School of Stomatology, Zunyi Medical University, Zunyi, 563006, China
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5
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Jin J, Bai H, Yan H, Deng T, Li T, Xiao R, Fan L, Bai X, Ning H, Liu Z, Zhang K, Wu X, Liang K, Ma P, Gao X, Hu D. PRMT2 promotes HIV-1 latency by preventing nucleolar exit and phase separation of Tat into the Super Elongation Complex. Nat Commun 2023; 14:7274. [PMID: 37949879 PMCID: PMC10638354 DOI: 10.1038/s41467-023-43060-1] [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: 05/20/2023] [Accepted: 10/30/2023] [Indexed: 11/12/2023] Open
Abstract
The HIV-1 Tat protein hijacks the Super Elongation Complex (SEC) to stimulate viral transcription and replication. However, the mechanisms underlying Tat activation and inactivation, which mediate HIV-1 productive and latent infection, respectively, remain incompletely understood. Here, through a targeted complementary DNA (cDNA) expression screening, we identify PRMT2 as a key suppressor of Tat activation, thus contributing to proviral latency in multiple cell line latency models and in HIV-1-infected patient CD4+ T cells. Our data reveal that the transcriptional activity of Tat is oppositely regulated by NPM1-mediated nucleolar retention and AFF4-induced phase separation in the nucleoplasm. PRMT2 preferentially methylates Tat arginine 52 (R52) to reinforce its nucleolar sequestration while simultaneously counteracting its incorporation into the SEC droplets, thereby leading to its functional inactivation to promote proviral latency. Thus, our studies unveil a central and unappreciated role for Tat methylation by PRMT2 in connecting its subnuclear distribution, liquid droplet formation, and transactivating function, which could be therapeutically targeted to eradicate latent viral reservoirs.
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Affiliation(s)
- Jiaxing Jin
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Hui Bai
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Han Yan
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Ting Deng
- Key Laboratory of Breast Cancer Prevention and Therapy of Ministry of Education, Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, 300060, Tianjin, China
| | - Tianyu Li
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, 430071, Wuhan, China
| | - Ruijing Xiao
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, 430071, Wuhan, China
| | - Lina Fan
- Department of Infectious Diseases, Tianjin Second People's Hospital, Nankai University, 300192, Tianjin, China
| | - Xue Bai
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Hanhan Ning
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China
| | - Zhe Liu
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Kai Zhang
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Xudong Wu
- The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, School of Basic Medical Sciences, Tianjin Medical University, 300070, Tianjin, China
| | - Kaiwei Liang
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, 430071, Wuhan, China
| | - Ping Ma
- Department of Infectious Diseases, Tianjin Second People's Hospital, Nankai University, 300192, Tianjin, China.
| | - Xin Gao
- State Key Laboratory of Experimental Hematology, National Clinical Research Center for Blood Diseases, Haihe Laboratory of Cell Ecosystem, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, 300020, Tianjin, China.
- Tianjin Institutes of Health Science, 301600, Tianjin, China.
| | - Deqing Hu
- National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, The Province and Ministry Co-sponsored Collaborative Innovation Center for Medical Epigenetics, State Key Laboratory of Experimental Hematology, Key Laboratory of Immune Microenvironment and Disease of Ministry of Education, Department of Cell Biology, School of Basic Medicine, Tianjin Medical University Cancer Institute and Hospital, Tianjin Medical University, 300070, Tianjin, China.
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6
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Hope I, Endicott JA, Watt JE. Emerging approaches to CDK inhibitor development, a structural perspective. RSC Chem Biol 2023; 4:146-164. [PMID: 36794018 PMCID: PMC9906319 DOI: 10.1039/d2cb00201a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 12/06/2022] [Indexed: 12/15/2022] Open
Abstract
Aberrant activity of the cyclin-dependent kinase family is frequently noted in a number of diseases identifying them as potential targets for drug development. However, current CDK inhibitors lack specificity owing to the high sequence and structural conservation of the ATP binding cleft across family members, highlighting the necessity of finding novel modes of CDK inhibition. The wealth of structural information regarding CDK assemblies and inhibitor complexes derived from X-ray crystallographic studies has been recently complemented through the use of cryo-electron microscopy. These recent advances have provided insights into the functional roles and regulatory mechanisms of CDKs and their interaction partners. This review explores the conformational malleability of the CDK subunit, the importance of SLiM recognition sites in CDK complexes, the progress made in chemically induced CDK degradation and how these studies can contribute to CDK inhibitor design. Additionally, fragment-based drug discovery can be utilised to identify small molecules that bind to allosteric sites on the CDK surface employing interactions which mimic those of native protein-protein interactions. These recent structural advances in CDK inhibitor mechanisms and in chemical probes which do not occupy the orthosteric ATP binding site can provide important insights for targeted CDK therapies.
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Affiliation(s)
- Ian Hope
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Paul O'Gorman Building, Framlington Place Newcastle upon Tyne NE2 4HH UK
| | - Jane A Endicott
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Paul O'Gorman Building, Framlington Place Newcastle upon Tyne NE2 4HH UK
| | - Jessica E Watt
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Paul O'Gorman Building, Framlington Place Newcastle upon Tyne NE2 4HH UK
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7
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Fujinaga K, Huang F, Peterlin BM. P-TEFb: The master regulator of transcription elongation. Mol Cell 2023; 83:393-403. [PMID: 36599353 PMCID: PMC9898187 DOI: 10.1016/j.molcel.2022.12.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 11/10/2022] [Accepted: 12/08/2022] [Indexed: 01/05/2023]
Abstract
The positive transcription elongation factor b (P-TEFb) is composed of cyclins T1 or T2 and cyclin-dependent kinase 9 that regulate the elongation phase of transcription by RNA polymerase II. By antagonizing negative elongation factors and phosphorylating the C-terminal domain of RNA polymerase II, P-TEFb facilitates the elongation and co-transcriptional processing of nascent transcripts. This step is critical for the expression of most eukaryotic genes. In growing cells, P-TEFb is regulated negatively by its reversible associations with HEXIM1/2 in the 7SK snRNP and positively by a number of transcription factors, as well as the super elongation complex. In resting cells, P-TEFb falls apart, and cyclin T1 is degraded by the proteasome. This complex regulation of P-TEFb has evolved for the precise temporal and spatial regulation of gene expression in the organism. Its dysregulation contributes to inflammatory and neoplastic conditions.
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Affiliation(s)
- Koh Fujinaga
- Departments of Medicine, Microbiology and Immunology, University of California at San Francisco, San Francisco, CA 94143, USA.
| | - Fang Huang
- Departments of Medicine, Microbiology and Immunology, University of California at San Francisco, San Francisco, CA 94143, USA
| | - B Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, University of California at San Francisco, San Francisco, CA 94143, USA.
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8
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Tang D, Wang Y, Dong X, Yuan Y, Kang F, Tian W, Wang K, Li H, Qi S. Scramblases and virus infection. Bioessays 2022; 44:e2100261. [DOI: 10.1002/bies.202100261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 09/26/2022] [Accepted: 09/27/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Dan Tang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Yichang Wang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Xiuju Dong
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Yiqiong Yuan
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Fanchen Kang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Weidong Tian
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Kunjie Wang
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Hong Li
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
| | - Shiqian Qi
- Department of Urology Institute of Urology (Laboratory of Reconstructive Urology) State Key Laboratory of Oral Disease West China Hospital of Stomatology West China Hospital Sichuan University Chengdu Sichuan China
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9
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Li J, Liu T, Song Y, Wang M, Liu L, Zhu H, Li Q, Lin J, Jiang H, Chen K, Zhao K, Wang M, Zhou H, Lin H, Luo C. Discovery of Small-Molecule Degraders of the CDK9-Cyclin T1 Complex for Targeting Transcriptional Addiction in Prostate Cancer. J Med Chem 2022; 65:11034-11057. [PMID: 35925880 DOI: 10.1021/acs.jmedchem.2c00257] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aberrant hyperactivation of cyclins results in carcinogenesis and therapy resistance in cancers. Direct degradation of the specific cyclin or cyclin-dependent kinase (CDK)-cyclin complex by small-molecule degraders remains a great challenge. Here, we applied the first application of hydrophobic tagging to induce degradation of CDK9-cyclin T1 heterodimer, which is required to keep productive transcription of oncogenes in cancers. LL-K9-3 was identified as a potent small-molecule degrader of CDK9-cyclin T1. Quantitative and time-resolved proteome profiling exhibited LL-K9-3 induced selective and synchronous degradation of CDK9 and cyclin T1. The expressions of androgen receptor (AR) and cMyc were reduced by LL-K9-3 in 22RV1 cells. LL-K9-3 exhibited enhanced anti-proliferative and pro-apoptotic effects compared with its parental CDK9 inhibitor SNS032 and suppressed downstream signaling of CDK9 and AR more effectively than SNS032. Moreover, LL-K9-3 inhibited AR and Myc-driven oncogenic transcriptional programs and exerted stronger inhibitory effects on several intrinsic target genes of AR than the monomeric CDK9 PROTAC (Thal-SNS032).
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Affiliation(s)
- Jiacheng Li
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
| | - Ting Liu
- School of Pharmacy, Fujian Medical University, Fuzhou 350122, China
| | - Yuanli Song
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China.,Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Mingyu Wang
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
| | - Liping Liu
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
| | - Hongwen Zhu
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China.,Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Qi Li
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
| | - Jin Lin
- School of Pharmacy, Fujian Medical University, Fuzhou 350122, China
| | - Hualiang Jiang
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
| | - Kaixian Chen
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, 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 264005, China
| | - Mingliang Wang
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Hu Zhou
- University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China.,Department of Analytical Chemistry and CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
| | - Hua Lin
- The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou 350117, China
| | - Cheng Luo
- School of Pharmacy, Fujian Medical University, Fuzhou 350122, China.,The Center for Chemical Biology, Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China.,School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
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10
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Ning S, Wang H, Zeng C, Zhao Y. Prediction of allosteric druggable pockets of cyclin-dependent kinases. Brief Bioinform 2022; 23:6643454. [PMID: 35830869 DOI: 10.1093/bib/bbac290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/07/2022] [Accepted: 06/24/2022] [Indexed: 11/13/2022] Open
Abstract
Cyclin-dependent kinase (Cdk) proteins play crucial roles in the cell cycle progression and are thus attractive drug targets for therapy against such aberrant cell cycle processes as cancer. Since most of the available Cdk inhibitors target the highly conserved catalytic ATP pocket and their lack of specificity often lead to side effects, it is imperative to identify and characterize less conserved non-catalytic pockets capable of interfering with the kinase activity allosterically. However, a systematic analysis of these allosteric druggable pockets is still in its infancy. Here, we summarize the existing Cdk pockets and their selectivity. Then, we outline a network-based pocket prediction approach (NetPocket) and illustrate its utility for systematically identifying the allosteric druggable pockets with case studies. Finally, we discuss potential future directions and their challenges.
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Affiliation(s)
- Shangbo Ning
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan, 430079, China
| | - Huiwen Wang
- School of Physics and Engineering, Henan University of Science and Technology, Luoyang 471023, China
| | - Chen Zeng
- Department of Physics, The George Washington University, Washington, DC 20052, USA
| | - Yunjie Zhao
- Institute of Biophysics and Department of Physics, Central China Normal University, Wuhan, 430079, China
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11
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Huang F, Nguyen TT, Echeverria I, Rakesh R, Cary DC, Paculova H, Sali A, Weiss A, Peterlin BM, Fujinaga K. Reversible phosphorylation of cyclin T1 promotes assembly and stability of P-TEFb. eLife 2021; 10:68473. [PMID: 34821217 PMCID: PMC8648303 DOI: 10.7554/elife.68473] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 11/19/2021] [Indexed: 01/06/2023] Open
Abstract
The positive transcription elongation factor b (P-TEFb) is a critical coactivator for transcription of most cellular and viral genes, including those of HIV. While P-TEFb is regulated by 7SK snRNA in proliferating cells, P-TEFb is absent due to diminished levels of CycT1 in quiescent and terminally differentiated cells, which has remained unexplored. In these cells, we found that CycT1 not bound to CDK9 is rapidly degraded. Moreover, productive CycT1:CDK9 interactions are increased by PKC-mediated phosphorylation of CycT1 in human cells. Conversely, dephosphorylation of CycT1 by PP1 reverses this process. Thus, PKC inhibitors or removal of PKC by chronic activation results in P-TEFb disassembly and CycT1 degradation. This finding not only recapitulates P-TEFb depletion in resting CD4+ T cells but also in anergic T cells. Importantly, our studies reveal mechanisms of P-TEFb inactivation underlying T cell quiescence, anergy, and exhaustion as well as proviral latency and terminally differentiated cells.
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Affiliation(s)
- Fang Huang
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
| | - Trang Tt Nguyen
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States.,The Howard Hughes Medical Institute, San Francisco, United States
| | - Ignacia Echeverria
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Departmentof Cellular Molecular Pharmacology, California Institute for Quantitative Biosciences (QBI), and Department of Bioengineering and Therapeutic Sciences, San Francisco, United States
| | - Ramachandran Rakesh
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Departmentof Cellular Molecular Pharmacology, California Institute for Quantitative Biosciences (QBI), and Department of Bioengineering and Therapeutic Sciences, San Francisco, United States
| | - Daniele C Cary
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
| | - Hana Paculova
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Department of Bioengineering and Therapeutic Sciences, Department of Pharmaceutical Chemistry, and California Institute for Quantitative Biosciences (QBI), San Francisco, United States
| | - Arthur Weiss
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States.,The Howard Hughes Medical Institute, San Francisco, United States
| | - Boris Matija Peterlin
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
| | - Koh Fujinaga
- Departments of Medicine, Microbiology and Immunology, University of California, San Francisco, San Francisco, United States.,Department of Medicine, San Francisco, United States
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12
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Russi M, Marson D, Fermeglia A, Aulic S, Fermeglia M, Laurini E, Pricl S. The fellowship of the RING: BRCA1, its partner BARD1 and their liaison in DNA repair and cancer. Pharmacol Ther 2021; 232:108009. [PMID: 34619284 DOI: 10.1016/j.pharmthera.2021.108009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 08/22/2021] [Accepted: 09/20/2021] [Indexed: 12/12/2022]
Abstract
The breast cancer type 1 susceptibility protein (BRCA1) and its partner - the BRCA1-associated RING domain protein 1 (BARD1) - are key players in a plethora of fundamental biological functions including, among others, DNA repair, replication fork protection, cell cycle progression, telomere maintenance, chromatin remodeling, apoptosis and tumor suppression. However, mutations in their encoding genes transform them into dangerous threats, and substantially increase the risk of developing cancer and other malignancies during the lifetime of the affected individuals. Understanding how BRCA1 and BARD1 perform their biological activities therefore not only provides a powerful mean to prevent such fatal occurrences but can also pave the way to the development of new targeted therapeutics. Thus, through this review work we aim at presenting the major efforts focused on the functional characterization and structural insights of BRCA1 and BARD1, per se and in combination with all their principal mediators and regulators, and on the multifaceted roles these proteins play in the maintenance of human genome integrity.
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Affiliation(s)
- Maria Russi
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Domenico Marson
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Alice Fermeglia
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Suzana Aulic
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Maurizio Fermeglia
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Erik Laurini
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Sabrina Pricl
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy; Department of General Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland.
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13
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Chen Y, Vos SM, Dienemann C, Ninov M, Urlaub H, Cramer P. Allosteric transcription stimulation by RNA polymerase II super elongation complex. Mol Cell 2021; 81:3386-3399.e10. [PMID: 34265249 DOI: 10.1016/j.molcel.2021.06.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 05/19/2021] [Accepted: 06/17/2021] [Indexed: 01/11/2023]
Abstract
The super elongation complex (SEC) contains the positive transcription elongation factor b (P-TEFb) and the subcomplex ELL2-EAF1, which stimulates RNA polymerase II (RNA Pol II) elongation. Here, we report the cryoelectron microscopy (cryo-EM) structure of ELL2-EAF1 bound to a RNA Pol II elongation complex at 2.8 Å resolution. The ELL2-EAF1 dimerization module directly binds the RNA Pol II lobe domain, explaining how SEC delivers P-TEFb to RNA Pol II. The same site on the lobe also binds the initiation factor TFIIF, consistent with SEC binding only after the transition from transcription initiation to elongation. Structure-guided functional analysis shows that the stimulation of RNA elongation requires the dimerization module and the ELL2 linker that tethers the module to the RNA Pol II protrusion. Our results show that SEC stimulates elongation allosterically and indicate that this stimulation involves stabilization of a closed conformation of the RNA Pol II active center cleft.
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Affiliation(s)
- Ying Chen
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - Seychelle M Vos
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - Christian Dienemann
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany
| | - Momchil Ninov
- Max Planck Institute for Biophysical Chemistry, Bioanalytical Mass Spectrometry, Am Fassberg 11, 37077 Göttingen, Germany; University Medical Center Göttingen, Institute of Clinical Chemistry, Bioanalytics Group, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Henning Urlaub
- Max Planck Institute for Biophysical Chemistry, Bioanalytical Mass Spectrometry, Am Fassberg 11, 37077 Göttingen, Germany; University Medical Center Göttingen, Institute of Clinical Chemistry, Bioanalytics Group, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Patrick Cramer
- Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Am Fassberg 11, 37077 Göttingen, Germany.
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14
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Li X, Song Y. Structure, function and inhibition of critical protein-protein interactions involving mixed lineage leukemia 1 and its fusion oncoproteins. J Hematol Oncol 2021; 14:56. [PMID: 33823889 PMCID: PMC8022399 DOI: 10.1186/s13045-021-01057-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/05/2021] [Indexed: 12/13/2022] Open
Abstract
Mixed lineage leukemia 1 (MLL1, also known as MLL or KMT2A) is an important transcription factor and histone-H3 lysine-4 (H3K4) methyltransferase. It is a master regulator for transcription of important genes (e.g., Hox genes) for embryonic development and hematopoiesis. However, it is largely dispensable in matured cells. Dysregulation of MLL1 leads to overexpression of certain Hox genes and eventually leukemia initiation. Chromosome translocations involving MLL1 cause ~ 75% of acute leukemia in infants and 5–10% in children and adults with a poor prognosis. Targeted therapeutics against oncogenic fusion MLL1 (onco-MLL1) are therefore needed. Onco-MLL1 consists of the N-terminal DNA-interacting domains of MLL1 fused with one of > 70 fusion partners, among which transcription cofactors AF4, AF9 and its paralog ENL, and ELL are the most frequent. Wild-type (WT)- and onco-MLL1 involve numerous protein–protein interactions (PPI), which play critical roles in regulating gene expression in normal physiology and leukemia. Moreover, WT-MLL1 has been found to be essential for MLL1-rearranged (MLL1-r) leukemia. Rigorous studies of such PPIs have been performed and much progress has been achieved in understanding their structures, structure–function relationships and the mechanisms for activating gene transcription as well as leukemic transformation. Inhibition of several critical PPIs by peptides, peptidomimetic or small-molecule compounds has been explored as a therapeutic approach for MLL1-r leukemia. This review summarizes the biological functions, biochemistry, structure and inhibition of the critical PPIs involving MLL1 and its fusion partner proteins. In addition, challenges and perspectives of drug discovery targeting these PPIs for the treatment of MLL1-r leukemia are discussed.
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Affiliation(s)
- Xin Li
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, 77030, USA
| | - Yongcheng Song
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, 77030, USA. .,Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX, 77030, USA.
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15
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Tatum NJ, Endicott JA. Chatterboxes: the structural and functional diversity of cyclins. Semin Cell Dev Biol 2020; 107:4-20. [PMID: 32414682 DOI: 10.1016/j.semcdb.2020.04.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/16/2022]
Abstract
Proteins of the cyclin family have divergent sequences and execute diverse roles within the cell while sharing a common fold: the cyclin box domain. Structural studies of cyclins have played a key role in our characterization and understanding of cellular processes that they control, though to date only ten of the 29 CDK-activating cyclins have been structurally characterized by X-ray crystallography or cryo-electron microscopy with or without their cognate kinases. In this review, we survey the available structures of human cyclins, highlighting their molecular features in the context of their cellular roles. We pay particular attention to how cyclin activity is regulated through fine control of degradation motif recognition and ubiquitination. Finally, we discuss the emergent roles of cyclins independent of their roles as cyclin-dependent protein kinase activators, demonstrating the cyclin box domain to be a versatile and generalized scaffolding domain for protein-protein interactions across the cellular machinery.
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Affiliation(s)
- Natalie J Tatum
- Cancer Research UK Newcastle Drug Discovery Unit, Newcastle Centre for Cancer, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Jane A Endicott
- Cancer Research UK Newcastle Drug Discovery Unit, Newcastle Centre for Cancer, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom.
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16
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Chen Y, Wang Y, Lin W, Sheng R, Wu Y, Xu R, Zhou C, Yuan Q. AFF1 inhibits adipogenic differentiation via targeting TGM2 transcription. Cell Prolif 2020; 53:e12831. [PMID: 32441391 PMCID: PMC7309944 DOI: 10.1111/cpr.12831] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/16/2020] [Accepted: 04/28/2020] [Indexed: 02/05/2023] Open
Abstract
OBJECTIVES AF4/FMR2 family member 1 (AFF1), known as a central scaffolding protein of super elongation complex (SEC), regulates gene transcription. We previously reported that AFF1 inhibited osteogenic differentiation of human mesenchymal stromal/stem cells (hMSCs). However, its role in adipogenic differentiation has not been elucidated. MATERIALS AND METHODS hMSCs and 3T3-L1 pre-adipocytes were cultured and induced for adipogenic differentiation. Small interfering RNAs (siRNAs) were applied to deplete AFF1 while lentiviruses expressing HA-Aff1 were used for overexpression. Oil Red O staining, triglyceride (TAG) quantification, quantitative real-time PCR (qPCR), Western blot analysis, immunofluorescence staining, RNA sequencing (RNA-seq) analysis and ChIP-qPCR were performed. To evaluate the adipogenesis in vivo, BALB/c nude mice were subcutaneously injected with Aff1-overexpressed 3T3-L1 pre-adipocytes. RESULTS AFF1 depletion leads to an enhanced adipogenesis in both hMSCs and 3T3-L1 pre-adipocytes. Overexpression of Aff1 in 3T3-L1 cells results in the reduction of adipogenic differentiation and less adipose tissue formation in vivo. Mechanistically, AFF1 binds to the promoter region of Tgm2 gene and regulates its transcription. Overexpression of Tgm2 largely rescues adipogenic differentiation of Aff1-deficient cells. CONCLUSIONS Our data indicate that AFF1 inhibits adipogenic differentiation by regulating the transcription of TGM2.
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Affiliation(s)
- Yaqian Chen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yuan Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Weimin Lin
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Rui Sheng
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yunshu Wu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Ruoshi Xu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Chenchen Zhou
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Quan Yuan
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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17
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Zhang Y, Xiao Q, Wu Z, Xu R, Zou S, Zhou C. AFF4 enhances odontogenic differentiation of human dental pulp cells. Biochem Biophys Res Commun 2020; 525:687-692. [PMID: 32139123 DOI: 10.1016/j.bbrc.2020.02.122] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 02/20/2020] [Indexed: 02/08/2023]
Abstract
AFF4 is a component of super elongation complex (SECs) and functions as a scaffold protein to bridge the transcription elongation factors. It is associated with leukemia, HIV transcription, and head neck cancer. However, its role in odontogenic differentiation of dental pulp cells (DPCs) is unclear. Here, we show the expression of AFF4 is increased during odontogenesis. Depletion of AFF4 in human DPCs leads to a decrease of alkaline phosphatase (ALP) activity, calcium mineralization and odontogenic-related genes expression. On the contrary, Lentivirus-mediated overexpression of AFF4 induces the odontogenic potential of DPCs. Mechanistically, we found AFF4 regulates the transcription of NFIC, a key factor for tooth root formation. Overexpression of NFIC successfully rescues the restricted differentiation of AFF4-depleted cells. Our data demonstrate that AFF4 serves as a previously unknown regulator of odontogenesis.
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Affiliation(s)
- Yuning Zhang
- State Key Laboratory of Oral Diseases & National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China
| | - Qingyue Xiao
- State Key Laboratory of Oral Diseases & National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China
| | - Zuping Wu
- State Key Laboratory of Oral Diseases & National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China
| | - Ruoshi Xu
- State Key Laboratory of Oral Diseases & National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China
| | - Shujuan Zou
- State Key Laboratory of Oral Diseases & National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China; Department of Orthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China
| | - Chenchen Zhou
- State Key Laboratory of Oral Diseases & National Clinical Research Centre for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China; Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, China.
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18
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Tang D, Chen C, Liao G, Liu J, Liao B, Huang Q, Chen Q, Zhao J, Jiang H, Duan J, Huang J, Wang K, Wang J, Zhou C, Chu W, Li W, Sun B, Li Z, Dai L, Fu X, Cheng W, Xue Y, Qi S. Structural and functional insight into the effect of AFF4 dimerization on activation of HIV-1 proviral transcription. Cell Discov 2020; 6:7. [PMID: 32128251 PMCID: PMC7026398 DOI: 10.1038/s41421-020-0142-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 12/23/2019] [Indexed: 02/05/2023] Open
Abstract
Super elongation complex (SEC) is a positive regulator of RNA polymerase II, which is required for HIV-1 proviral transcription. AFF1/4 is the scaffold protein that recruits other components of SEC and forms dimer depending on its THD domain (TPRL with Handle Region Dimerization Domain). Here we report the crystal structure of the human AFF4-THD at the resolution of 2.4 Å. The α4, α5, and α6 of one AFF4-THD mediate the formation of a dimer and pack tightly against the equivalent part of the second molecule in the dimer of AFF-THD. Mutagenesis analysis revealed that single mutations of either Phe1014 or Tyr1096 of AFF4 to alanine impair the formation of the AFF4 dimer. In addition, transactivation assay also indicated that Phe1014 and Tyr1096 of AFF4 are critical to the transactivation activity of AFF4. Interestingly, the corresponding residues Phe1063 and Tyr1145 in AFF1 have an effect on the transactivation of HIV-1 provirus. However, such mutations of AFF1/4 have no effect on the interaction of AFF1/4 with other subunits of the SEC. Together, our data demonstrated that the dimerization of AFF1/4 is essential to transactivation of HIV-1 provirus.
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Affiliation(s)
- Dan Tang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Chunjing Chen
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, Fujian 361102 China
| | - Ga Liao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041 China
| | - Jiaming Liu
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Banghua Liao
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - QingQing Huang
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, Fujian 361102 China
| | - Qianqian Chen
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Jiahui Zhao
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Hui Jiang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Jinsong Duan
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084 China
| | - Jin Huang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Kunjie Wang
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Jiawei Wang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084 China
| | - Cuiyan Zhou
- School of Biomedicine in Tsinghua University, National Protein Science Facility, Beijing, 100084 China
| | - Wendan Chu
- School of Biomedicine in Tsinghua University, National Protein Science Facility, Beijing, 100084 China
| | - Wenqi Li
- School of Biomedicine in Tsinghua University, National Protein Science Facility, Beijing, 100084 China
| | - Bo Sun
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, 201204 China
| | - Zhonghan Li
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Lunzhi Dai
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Xianghui Fu
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Wei Cheng
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
| | - Yuhua Xue
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, Fujian 361102 China
| | - Shiqian Qi
- Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, College of Life Sciences, Sichuan University, and Collaborative Innovation Center for Biotherapy, Chengdu, Sichuan 610041 China
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19
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Lee S, Liu H, Hill R, Chen C, Hong X, Crawford F, Kingsley M, Zhang Q, Liu X, Chen Z, Lengeling A, Bernt KM, Marrack P, Kappler J, Zhou Q, Li CY, Xue Y, Hansen K, Zhang G. JMJD6 cleaves MePCE to release positive transcription elongation factor b (P-TEFb) in higher eukaryotes. eLife 2020; 9:53930. [PMID: 32048991 PMCID: PMC7064345 DOI: 10.7554/elife.53930] [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: 11/25/2019] [Accepted: 02/11/2020] [Indexed: 12/19/2022] Open
Abstract
More than 30% of genes in higher eukaryotes are regulated by promoter-proximal pausing of RNA polymerase II (Pol II). Phosphorylation of Pol II CTD by positive transcription elongation factor b (P-TEFb) is a necessary precursor event that enables productive transcription elongation. The exact mechanism on how the sequestered P-TEFb is released from the 7SK snRNP complex and recruited to Pol II CTD remains unknown. In this report, we utilize mouse and human models to reveal methylphosphate capping enzyme (MePCE), a core component of the 7SK snRNP complex, as the cognate substrate for Jumonji domain-containing 6 (JMJD6)’s novel proteolytic function. Our evidences consist of a crystal structure of JMJD6 bound to methyl-arginine, enzymatic assays of JMJD6 cleaving MePCE in vivo and in vitro, binding assays, and downstream effects of Jmjd6 knockout and overexpression on Pol II CTD phosphorylation. We propose that JMJD6 assists bromodomain containing 4 (BRD4) to recruit P-TEFb to Pol II CTD by disrupting the 7SK snRNP complex. In animals, an enzyme known as RNA polymerase II (Pol II for short) is a key element of the transcription process, whereby the genetic information contained in DNA is turned into messenger RNA molecules in the cells, which can then be translated to proteins. To perform this task, Pol II needs to be activated by a complex of proteins called P-TEFb; however, P-TEFb is usually found in an inactive form held by another group of proteins. Yet, it is unclear how P-TEFb is released and allowed to activate Pol II. Scientists have speculated that another protein called JMJD6 (Jumonji domain-containing 6) is important for P-TEFb to activate Pol II. Various roles for JMJD6 have been proposed, but its exact purpose remains unclear. Recently, two enzymes closely related to JMJD6 were found to be able to make precise cuts in other proteins; Lee, Liu et al. therefore wanted to test whether this is also true of JMJD6. Experiments using purified JMJD6 showed that it could make a cut in an enzyme called MePCE, which belongs to the group of proteins that hold P-TEFb in its inactive form. Lee, Liu et al. then tested the relationships between these proteins in living human and mouse cells. The levels of activated Pol II were lower in cells without JMJD6 and higher in those without MePCE. Together, the results suggest that JMJD6 cuts MePCE to release P-TEFb, which then activates Pol II. JMJD6 appears to know where to cut by following a specific pattern of elements in the structure of MePCE. When MePCE was mutated so that the pattern changed, JMJD6 was unable to cut it. These results suggest that JMJD6 and related enzymes belong to a new family of proteases, the molecular scissors that can cleave other proteins. The molecules that regulate transcription often are major drug targets, for example in the fight against cancer. Ultimately, understanding the role of JMJD6 might help to identify new avenues for cancer drug development.
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Affiliation(s)
- Schuyler Lee
- Department of Biomedical Research, National Jewish Health, Denver, United States.,Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, United States
| | - Haolin Liu
- Department of Biomedical Research, National Jewish Health, Denver, United States.,Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, United States
| | - Ryan Hill
- Department of Genetics and Biochemistry, School of Medicine, University of Colorado, Aurora, United States
| | - Chunjing Chen
- State Key Laboratory of Cellular Stress Biology, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Xia Hong
- Department of Biomedical Research, National Jewish Health, Denver, United States.,Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, United States
| | - Fran Crawford
- Department of Biomedical Research, National Jewish Health, Denver, United States
| | - Molly Kingsley
- Department of Pediatrics, Children Hospital, University of Colorado, Aurora, United States.,Department of Pediatrics and the Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, United States
| | - Qianqian Zhang
- State Key Laboratory of Agrobiotechnology, China Agriculture University, Beijing, China
| | - Xinjian Liu
- Department of Dermatology, Duke University, Durham, United States
| | - Zhongzhou Chen
- State Key Laboratory of Agrobiotechnology, China Agriculture University, Beijing, China
| | | | - Kathrin Maria Bernt
- Department of Pediatrics and the Center for Childhood Cancer Research, Children's Hospital of Philadelphia, Philadelphia, United States.,Department of Molecular and Cell Biology, University of California, Berkeley, United States
| | - Philippa Marrack
- Department of Biomedical Research, National Jewish Health, Denver, United States.,Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, United States
| | - John Kappler
- Department of Biomedical Research, National Jewish Health, Denver, United States.,Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, United States
| | - Qiang Zhou
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States
| | - Chuan-Yuan Li
- Department of Dermatology, Duke University, Durham, United States
| | - Yuhua Xue
- State Key Laboratory of Cellular Stress Biology, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Kirk Hansen
- Department of Genetics and Biochemistry, School of Medicine, University of Colorado, Aurora, United States
| | - Gongyi Zhang
- Department of Biomedical Research, National Jewish Health, Denver, United States.,Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, United States
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20
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AFF1 acetylation by p300 temporally inhibits transcription during genotoxic stress response. Proc Natl Acad Sci U S A 2019; 116:22140-22151. [PMID: 31611376 PMCID: PMC6823056 DOI: 10.1073/pnas.1907097116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Mammalian cells are constantly exposed to genotoxic agents that can lead to DNA damage, genomic instability, and diseases, including cancers. Maintenance of genomic stability, a prerequisite for survival and proper functions of cells, is facilitated by the cellular DNA repair machinery. One of the earliest responses to DNA damage is a transient inhibition of transcription to avoid fatal collisions between the DNA repair and transcriptional machineries. However, the mechanisms underlying this early transcriptional inhibition are poorly understood. Our study establishes a critical role for AFF1, a key component of super elongation complex, in early transcription inhibition and cell survival upon DNA damage, as well as a mechanism involving p300-mediated acetylation of AFF1 and consequent inactivation of the super elongation complex. Soon after exposure to genotoxic reagents, mammalian cells inhibit transcription to prevent collisions with repair machinery and to mount a proper DNA damage response. However, mechanisms underlying early transcriptional inhibition are poorly understood. In this report, we show that site-specific acetylation of super elongation complex (SEC) subunit AFF1 by p300 reduces its interaction with other SEC components and impairs P-TEFb−mediated C-terminal domain phosphorylation of RNA polymerase II both in vitro and in vivo. Reexpression of wild-type AFF1, but not an acetylation mimic mutant, restores SEC component recruitment and target gene expression in AFF1 knockdown cells. Physiologically, we show that, upon genotoxic exposure, p300-mediated AFF1 acetylation is dynamic and strongly correlated with concomitant global down-regulation of transcription—and that this can be reversed by overexpression of an acetylation-defective AFF1 mutant. Therefore, we describe a mechanism of dynamic transcriptional regulation involving p300-mediated acetylation of a key elongation factor during genotoxic stress.
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21
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Chen Y, Cramer P. Structure of the super-elongation complex subunit AFF4 C-terminal homology domain reveals requirements for AFF homo- and heterodimerization. J Biol Chem 2019; 294:10663-10673. [PMID: 31147444 PMCID: PMC6615702 DOI: 10.1074/jbc.ra119.008577] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/27/2019] [Indexed: 12/12/2022] Open
Abstract
AF4/FMR2 family member 4 (AFF4) is the scaffold protein of the multisubunit super-elongation complex, which plays key roles in the release of RNA polymerase II from promoter-proximal pausing and in the transactivation of HIV-1 transcription. AFF4 consists of an intrinsically disordered N-terminal region that interacts with other super-elongation complex subunits and a C-terminal homology domain (CHD) that is conserved among AF4/FMR2 family proteins, including AFF1, AFF2, AFF3, and AFF4. Here, we solved the X-ray crystal structure of the CHD in human AFF4 (AFF4-CHD) to 2.2 Å resolution and characterized its biochemical properties. The structure disclosed that AFF4-CHD folds into a novel domain that consists of eight helices and is distantly related to tetratrico peptide repeat motifs. Our analyses further revealed that AFF4-CHD mediates the formation of an AFF4 homodimer or an AFF1-AFF4 heterodimer. Results from fluorescence anisotropy experiments suggested that AFF4-CHD interacts with both RNA and DNA in vitro Furthermore, we identified a surface loop region in AFF4-CHD as a substrate for the P-TEFb kinase cyclin-dependent kinase 9, which triggers release of polymerase II from promoter-proximal pausing sites. In conclusion, the AFF-CHD structure and biochemical analyses reported here reveal the molecular basis for the homo- and heterodimerization of AFF proteins and implicate the AFF4-CHD in nucleic acid interactions. The high conservation of the CHD among several other proteins suggests that our results are also relevant for understanding other CHD-containing proteins and their dimerization behavior.
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Affiliation(s)
- Ying Chen
- From the Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Patrick Cramer
- From the Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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22
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Krasnopolsky S, Marom L, Victor RA, Kuzmina A, Schwartz JC, Fujinaga K, Taube R. Fused in sarcoma silences HIV gene transcription and maintains viral latency through suppressing AFF4 gene activation. Retrovirology 2019; 16:16. [PMID: 31238957 PMCID: PMC6593535 DOI: 10.1186/s12977-019-0478-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/11/2019] [Indexed: 12/12/2022] Open
Abstract
Background The human immunodeficiency virus (HIV) cell reservoir is currently a main obstacle towards complete eradication of the virus. This infected pool is refractory to anti-viral therapy and harbors integrated proviruses that are transcriptionally repressed but replication competent. As transcription silencing is key for establishing the HIV reservoir, significant efforts have been made to understand the mechanism that regulate HIV gene transcription, and the role of the elongation machinery in promoting this step. However, while the role of the super elongation complex (SEC) in enhancing transcription activation of HIV is well established, the function of SEC in modulating viral latency is less defined and its cell partners are yet to be identified. Results In this study we identify fused in sarcoma (FUS) as a partner of AFF4 in cells. FUS inhibits the activation of HIV transcription by AFF4 and ELL2, and silences overall HIV gene transcription. Concordantly, depletion of FUS elevates the occupancy of AFF4 and Cdk9 on the viral promoter and activates HIV gene transcription. Live cell imaging demonstrates that FUS co-localizes with AFF4 within nuclear punctuated condensates, which are disrupted upon treating cells with aliphatic alcohol. In HIV infected cells, knockout of FUS delays the gradual entry of HIV into latency, and similarly promotes viral activation in a T cell latency model that is treated with JQ1. Finally, effects of FUS on HIV gene transcription are also exhibited genome wide, where FUS mainly occupies gene promoters at transcription starting sites, while its knockdown leads to an increase in AFF4 and Cdk9 occupancy on gene promoters of FUS affected genes. Conclusions Towards eliminating the HIV infected reservoir, understanding the mechanisms by which the virus persists in the face of therapy is important. Our observations show that FUS regulates both HIV and global gene transcription and modulates viral latency, thus can potentially serve as a target for future therapy that sets to reactivate HIV from its latent state. Electronic supplementary material The online version of this article (10.1186/s12977-019-0478-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Simona Krasnopolsky
- The Shraga Segal Department of Microbiology Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105, Beer Sheva, Israel
| | - Lital Marom
- The Shraga Segal Department of Microbiology Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105, Beer Sheva, Israel
| | - Rachel A Victor
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Alona Kuzmina
- The Shraga Segal Department of Microbiology Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105, Beer Sheva, Israel
| | - Jacob C Schwartz
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Koh Fujinaga
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Ran Taube
- The Shraga Segal Department of Microbiology Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, 84105, Beer Sheva, Israel.
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23
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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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24
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Nowacka M, Fernandes H, Kiliszek A, Bernat A, Lach G, Bujnicki JM. Specific interaction of zinc finger protein Com with RNA and the crystal structure of a self-complementary RNA duplex recognized by Com. PLoS One 2019; 14:e0214481. [PMID: 31022205 PMCID: PMC6483171 DOI: 10.1371/journal.pone.0214481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/13/2019] [Indexed: 11/18/2022] Open
Abstract
The bacteriophage Mu Com is a small zinc finger protein that binds to its cognate mom mRNA and activates its translation. The Mom protein, in turn, elicits a chemical modification (momification) of the bacteriophage genome, rendering the DNA resistant to cleavage by bacterial restriction endonucleases, and thereby protecting it from defense mechanisms of the host. We examined the basis of specificity in Com-RNA interactions by in vitro selection and probing of RNA structure. We demonstrated that Com recognizes a sequence motif within a hairpin-loop structure of its target RNA. Our data support the model of Com interaction with mom mRNA, in which Com binds to the short hairpin structure proximal to the so-called translation inhibition structure. We also observed that Com binds its target motif weakly if it is within an RNA duplex. These results suggest that the RNA structure, in addition to its sequence, is crucial for Com to recognize its target and that RNA conformational changes may constitute another level of Mom regulation. We determined a crystal structure of a Com binding site variant designed to form an RNA duplex preferentially. Our crystal model forms a 19-mer self-complementary double helix composed of the canonical and non-canonical base pairs. The helical parameters of crystalized RNA indicate why Com may bind it more weakly than a monomeric hairpin form.
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Affiliation(s)
- Martyna Nowacka
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
- * E-mail: ; (JMB)
| | - Humberto Fernandes
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Agnieszka Kiliszek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Poznan, Poland
| | - Agata Bernat
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Grzegorz Lach
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
| | - Janusz M. Bujnicki
- International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland
- Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland
- * E-mail: ; (JMB)
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25
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Wood DJ, Endicott JA. Structural insights into the functional diversity of the CDK-cyclin family. Open Biol 2019; 8:rsob.180112. [PMID: 30185601 PMCID: PMC6170502 DOI: 10.1098/rsob.180112] [Citation(s) in RCA: 141] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 08/10/2018] [Indexed: 12/17/2022] Open
Abstract
Since their characterization as conserved modules that regulate progression through the eukaryotic cell cycle, cyclin-dependent protein kinases (CDKs) in higher eukaryotic cells are now also emerging as significant regulators of transcription, metabolism and cell differentiation. The cyclins, though originally characterized as CDK partners, also have CDK-independent roles that include the regulation of DNA damage repair and transcriptional programmes that direct cell differentiation, apoptosis and metabolic flux. This review compares the structures of the members of the CDK and cyclin families determined by X-ray crystallography, and considers what mechanistic insights they provide to guide functional studies and distinguish CDK- and cyclin-specific activities. Aberrant CDK activity is a hallmark of a number of diseases, and structural studies can provide important insights to identify novel routes to therapy.
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Affiliation(s)
- Daniel J Wood
- Newcastle Cancer Centre, Northern Institute for Cancer Research, Medical School, Newcastle University, Paul O'Gorman Building, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Jane A Endicott
- Newcastle Cancer Centre, Northern Institute for Cancer Research, Medical School, Newcastle University, Paul O'Gorman Building, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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26
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Li Z, Wu J, Chavez L, Hoh R, Deeks SG, Pillai SK, Zhou Q. Reiterative Enrichment and Authentication of CRISPRi Targets (REACT) identifies the proteasome as a key contributor to HIV-1 latency. PLoS Pathog 2019; 15:e1007498. [PMID: 30645648 PMCID: PMC6333332 DOI: 10.1371/journal.ppat.1007498] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 12/03/2018] [Indexed: 02/06/2023] Open
Abstract
The establishment of HIV-1 latency gives rise to persistent chronic infection that requires life-long treatment. To reverse latency for viral eradiation, the HIV-1 Tat protein and its associated ELL2-containing Super Elongation Complexes (ELL2-SECs) are essential to activate HIV-1 transcription. Despite efforts to identify effective latency-reversing agents (LRA), avenues for exposing latent HIV-1 remain inadequate, prompting the need to identify novel LRA targets. Here, by conducting a CRISPR interference-based screen to reiteratively enrich loss-of-function genotypes that increase HIV-1 transcription in latently infected CD4+ T cells, we have discovered a key role of the proteasome in maintaining viral latency. Downregulating or inhibiting the proteasome promotes Tat-transactivation in cell line models. Furthermore, the FDA-approved proteasome inhibitors bortezomib and carfilzomib strongly synergize with existing LRAs to reactivate HIV-1 in CD4+ T cells from antiretroviral therapy-suppressed individuals without inducing cell activation or proliferation. Mechanistically, downregulating/inhibiting the proteasome elevates the levels of ELL2 and ELL2-SECs to enable Tat-transactivation, indicating the proteasome-ELL2 axis as a key regulator of HIV-1 latency and promising target for therapeutic intervention. To cure chronic HIV-1 infection requires reversal of HIV-1 latency from latently infected CD4+ T cells. A key step in HIV latency reversal is the recruitment of Super Elongation Complexes (SECs) that contain ELL2 by an HIV-encoded protein, Tat, to activate proviral transcription. To identify novel drug targets, we conducted a CRISPRi-based screen to enrich the sgRNAs that increase HIV transcription in latently infected CD4+ T cells. Three of the six most prominent hits in our screen are proteasome subunits. We further proved that antagonizing the proteasome promotes Tat-induced HIV-1 transcription in cell line-based latency models. Furthermore, we found that two FDA-approved proteasome inhibitors strongly synergize with existing LRAs ex vivo without inducing cell activation or proliferation. We further found that antagonizing the proteasome elevates the levels of ELL2 and ELL2-containing SECs in the cells, thus enabling Tat-transactivation. These results indicate that the proteasome-ELL2 axis is a key regulator of HIV-1 latency could potentially be targeted for therapeutic interventions.
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Affiliation(s)
- Zichong Li
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Jun Wu
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Leonard Chavez
- Vitalant Research Institute, San Francisco, California, United States of America
- University of California, San Francisco, California, United States of America
| | - Rebecca Hoh
- University of California, San Francisco, California, United States of America
| | - Steven G. Deeks
- University of California, San Francisco, California, United States of America
| | - Satish K. Pillai
- Vitalant Research Institute, San Francisco, California, United States of America
- University of California, San Francisco, California, United States of America
| | - Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- * E-mail:
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27
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Structural mechanism for HIV-1 TAR loop recognition by Tat and the super elongation complex. Proc Natl Acad Sci U S A 2018; 115:12973-12978. [PMID: 30514815 DOI: 10.1073/pnas.1806438115] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Promoter-proximal pausing by RNA polymerase II (Pol II) is a key regulatory step in human immunodeficiency virus-1 (HIV-1) transcription and thus in the reversal of HIV latency. By binding to the nascent transactivating response region (TAR) RNA, HIV-1 Tat recruits the human super elongation complex (SEC) to the promoter and releases paused Pol II. Structural studies of TAR interactions have been largely focused on interactions between the TAR bulge and the arginine-rich motif (ARM) of Tat. Here, the crystal structure of the TAR loop in complex with Tat and the SEC core was determined at a 3.5-Å resolution. The bound TAR loop is stabilized by cross-loop hydrogen bonds. It makes structure-specific contacts with the side chains of the Cyclin T1 Tat-TAR recognition motif (TRM) and the zinc-coordinating loop of Tat. The TAR loop phosphate backbone forms electrostatic and VDW interactions with positively charged side chains of the CycT1 TRM. Mutational analysis showed that these interactions contribute importantly to binding affinity. The Tat ARM was present in the crystallized construct; however, it was not visualized in the electron density, and the TAR bulge was not formed in the RNA construct used in crystallization. Binding assays showed that TAR bulge-Tat ARM interactions contribute less to TAR binding affinity than TAR loop interactions with the CycT1 TRM and Tat core. Thus, the TAR loop evolved to make high-affinity interactions with the TRM while Tat has three roles: scaffolding and stabilizing the TRM, making specific interactions through its zinc-coordinating loop, and making electrostatic interactions through its ARM.
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28
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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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29
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Faust TB, Li Y, Bacon CW, Jang GM, Weiss A, Jayaraman B, Newton BW, Krogan NJ, D'Orso I, Frankel AD. The HIV-1 Tat protein recruits a ubiquitin ligase to reorganize the 7SK snRNP for transcriptional activation. eLife 2018; 7:31879. [PMID: 29845934 PMCID: PMC5999396 DOI: 10.7554/elife.31879] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 05/26/2018] [Indexed: 12/12/2022] Open
Abstract
The HIV-1 Tat protein hijacks P-TEFb kinase to activate paused RNA polymerase II (RNAP II) at the viral promoter. Tat binds additional host factors, but it is unclear how they regulate RNAP II elongation. Here, we identify the cytoplasmic ubiquitin ligase UBE2O as critical for Tat transcriptional activity. Tat hijacks UBE2O to ubiquitinate the P-TEFb kinase inhibitor HEXIM1 of the 7SK snRNP, a fraction of which also resides in the cytoplasm bound to P-TEFb. HEXIM1 ubiquitination sequesters it in the cytoplasm and releases P-TEFb from the inhibitory 7SK complex. Free P-TEFb then becomes enriched in chromatin, a process that is also stimulated by treating cells with a CDK9 inhibitor. Finally, we demonstrate that UBE2O is critical for P-TEFb recruitment to the HIV-1 promoter. Together, the data support a unique model of elongation control where non-degradative ubiquitination of nuclear and cytoplasmic 7SK snRNP pools increases P-TEFb levels for transcriptional activation.
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Affiliation(s)
- Tyler B Faust
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Yang Li
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Curtis W Bacon
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Gwendolyn M Jang
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States.,J David Gladstone Institutes, San Francisco, United States
| | - Amit Weiss
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Bhargavi Jayaraman
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Billy W Newton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States.,J David Gladstone Institutes, San Francisco, United States
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States.,J David Gladstone Institutes, San Francisco, United States
| | - Iván D'Orso
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, United States
| | - Alan D Frankel
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
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30
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Asamitsu K, Fujinaga K, Okamoto T. HIV Tat/P-TEFb Interaction: A Potential Target for Novel Anti-HIV Therapies. Molecules 2018; 23:E933. [PMID: 29673219 PMCID: PMC6017356 DOI: 10.3390/molecules23040933] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 04/13/2018] [Accepted: 04/14/2018] [Indexed: 11/16/2022] Open
Abstract
Transcription is a crucial step in the life cycle of the human immunodeficiency virus type 1 (HIV 1) and is primarily involved in the maintenance of viral latency. Both viral and cellular transcription factors, including transcriptional activators, suppressor proteins and epigenetic factors, are involved in HIV transcription from the proviral DNA integrated within the host cell genome. Among them, the virus-encoded transcriptional activator Tat is the master regulator of HIV transcription. Interestingly, unlike other known transcriptional activators, Tat primarily activates transcriptional elongation and initiation by interacting with the cellular positive transcriptional elongation factor b (P-TEFb). In this review, we describe the molecular mechanism underlying how Tat activates viral transcription through interaction with P-TEFb. We propose a novel therapeutic strategy against HIV replication through blocking Tat action.
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Affiliation(s)
- Kaori Asamitsu
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
| | - Koh Fujinaga
- Department of Medicine, Microbiology and Immunology, University of California, San Francisco, CA 94143-0703, USA.
| | - Takashi Okamoto
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
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31
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Faust TB, Binning JM, Gross JD, Frankel AD. Making Sense of Multifunctional Proteins: Human Immunodeficiency Virus Type 1 Accessory and Regulatory Proteins and Connections to Transcription. Annu Rev Virol 2017; 4:241-260. [PMID: 28961413 DOI: 10.1146/annurev-virology-101416-041654] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Viruses are completely dependent upon cellular machinery to support replication and have therefore developed strategies to co-opt cellular processes to optimize infection and counter host immune defenses. Many viruses, including human immunodeficiency virus type 1 (HIV-1), encode a relatively small number of genes. Viruses with limited genetic content often encode multifunctional proteins that function at multiple stages of the viral replication cycle. In this review, we discuss the functions of HIV-1 regulatory (Tat and Rev) and accessory (Vif, Vpr, Vpu, and Nef) proteins. Each of these proteins has a highly conserved primary activity; however, numerous additional activities have been attributed to these viral proteins. We explore the possibility that HIV-1 proteins leverage their multifunctional nature to alter host transcriptional networks to elicit a diverse set of cellular responses. Although these transcriptional effects appear to benefit the virus, it is not yet clear whether they are strongly selected for during viral evolution or are a ripple effect from the primary function. As our detailed knowledge of these viral proteins improves, we will undoubtedly uncover how the multifunctional nature of these HIV-1 regulatory and accessory proteins, and in particular their transcriptional functions, work to drive viral pathogenesis.
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Affiliation(s)
- Tyler B Faust
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158; ,
| | - Jennifer M Binning
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158; ,
| | - John D Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, California 94158; ,
| | - Alan D Frankel
- Department of Biochemistry and Biophysics, University of California, San Francisco, California 94158; ,
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32
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AFF1 and AFF4 differentially regulate the osteogenic differentiation of human MSCs. Bone Res 2017; 5:17044. [PMID: 28955517 PMCID: PMC5613922 DOI: 10.1038/boneres.2017.44] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2017] [Revised: 06/18/2017] [Accepted: 06/18/2017] [Indexed: 02/05/2023] Open
Abstract
AFF1 and AFF4 belong to the AFF (AF4/FMR2) family of proteins, which function as scaffolding proteins linking two different transcription elongation factors, positive elongation factor b (P-TEFb) and ELL1/2, in super elongation complexes (SECs). Both AFF1 and AFF4 regulate gene transcription through elongation and chromatin remodeling. However, their function in the osteogenic differentiation of mesenchymal stem cells (MSCs) is unknown. In this study, we show that small interfering RNA (siRNA)-mediated depletion of AFF1 in human MSCs leads to increased alkaline phosphatase (ALP) activity, enhanced mineralization and upregulated expression of osteogenic-related genes. On the contrary, depletion of AFF4 significantly inhibits the osteogenic potential of MSCs. In addition, we confirm that overexpression of AFF1 and AFF4 differentially affects osteogenic differentiation in vitro and MSC-mediated bone formation in vivo. Mechanistically, we find that AFF1 regulates the expression of DKK1 via binding to its promoter region. Depletion of DKK1 in HA-AFF1-overexpressing MSCs abrogates the impairment of osteogenic differentiation. Moreover, we detect that AFF4 is enriched in the promoter region of ID1. AFF4 knockdown blunts the BRE luciferase activity, SP7 expression and ALP activity induced by BMP2 treatment. In conclusion, our data indicate that AFF1 and AFF4 differentially regulate the osteogenic differentiation of human MSCs.
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Ronsard L, Ganguli N, Singh VK, Mohankumar K, Rai T, Sridharan S, Pajaniradje S, Kumar B, Rai D, Chaudhuri S, Coumar MS, Ramachandran VG, Banerjea AC. Impact of Genetic Variations in HIV-1 Tat on LTR-Mediated Transcription via TAR RNA Interaction. Front Microbiol 2017; 8:706. [PMID: 28484443 PMCID: PMC5399533 DOI: 10.3389/fmicb.2017.00706] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/05/2017] [Indexed: 01/10/2023] Open
Abstract
HIV-1 evades host defense through mutations and recombination events, generating numerous variants in an infected patient. These variants with an undiminished virulence can multiply rapidly in order to progress to AIDS. One of the targets to intervene in HIV-1 replication is the trans-activator of transcription (Tat), a major regulatory protein that transactivates the long terminal repeat promoter through its interaction with trans-activation response (TAR) RNA. In this study, HIV-1 infected patients (n = 120) from North India revealed Ser46Phe (20%) and Ser61Arg (2%) mutations in the Tat variants with a strong interaction toward TAR leading to enhanced transactivation activities. Molecular dynamics simulation data verified that the variants with this mutation had a higher binding affinity for TAR than both the wild-type Tat and other variants that lacked Ser46Phe and Ser61Arg. Other mutations in Tat conferred varying affinities for TAR interaction leading to differential transactivation abilities. This is the first report from North India with a clinical validation of CD4 counts to demonstrate the influence of Tat genetic variations affecting the stability of Tat and its interaction with TAR. This study highlights the co-evolution pattern of Tat and predominant nucleotides for Tat activity, facilitating the identification of genetic determinants for the attenuation of viral gene expression.
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Affiliation(s)
- Larance Ronsard
- Laboratory of Virology, National Institute of ImmunologyDelhi, India.,Department of Microbiology, University College of Medical Sciences and Guru Teg Bahadur HospitalDelhi, India
| | - Nilanjana Ganguli
- Laboratory of Virology, National Institute of ImmunologyDelhi, India
| | - Vivek K Singh
- Centre for Bioinformatics, School of Life Sciences, Pondicherry UniversityPondicherry, India
| | - Kumaravel Mohankumar
- Department of Biochemistry and Molecular Biology, Pondicherry UniversityPondicherry, India.,Department of Veterinary Physiology and Pharmacology, Texas A&M University, College StationTX, USA
| | - Tripti Rai
- Department of Gastroenterology and Human Nutrition, All India Institute of Medical SciencesDelhi, India
| | - Subhashree Sridharan
- Department of Biochemistry and Molecular Biology, Pondicherry UniversityPondicherry, India.,Department of Symptom Research, The University of Texas MD Anderson Cancer Center, HoustonTX, USA
| | - Sankar Pajaniradje
- Department of Biochemistry and Molecular Biology, Pondicherry UniversityPondicherry, India
| | - Binod Kumar
- Department of Microbiology and Immunology, Rosalind Franklin University of Medicine and Science, ChicagoIL, USA
| | - Devesh Rai
- Department of Microbiology, All India Institute of Medical SciencesDelhi, India
| | - Suhnrita Chaudhuri
- Department of Neurological Surgery, Northwestern University, ChicagoIL, USA
| | - Mohane S Coumar
- Centre for Bioinformatics, School of Life Sciences, Pondicherry UniversityPondicherry, India
| | | | - Akhil C Banerjea
- Laboratory of Virology, National Institute of ImmunologyDelhi, India
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Kuzmina A, Krasnopolsky S, Taube R. Super elongation complex promotes early HIV transcription and its function is modulated by P-TEFb. Transcription 2017; 8:133-149. [PMID: 28340332 DOI: 10.1080/21541264.2017.1295831] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Early work on the control of transcription of the human immunodeficiency virus (HIV) laid the foundation for our current knowledge of how RNA Polymerase II is released from promoter-proximal pausing sites and transcription elongation is enhanced. The viral Tat activator recruits Positive Transcription Elongation Factor b (P-TEFb) and Super Elongation Complex (SEC) that jointly drive transcription elongation. While substantial progress in understanding the role of SEC in HIV gene transcription elongation has been obtained, defining of the mechanisms that govern SEC functions is still limited, and the role of SEC in controlling HIV transcription in the absence of Tat is less clear. Here we revisit the contribution of SEC in early steps of HIV gene transcription. In the absence of Tat, the AF4/FMR2 Family member 4 (AFF4) of SEC efficiently activates HIV transcription, while gene activation by its homolog AFF1 is substantially lower. Differential recruitment to the HIV promoter and association with Human Polymerase-Associated Factor complex (PAFc) play key role in this functional distinction between AFF4 and AFF1. Moreover, while depletion of cyclin T1 expression has subtle effects on HIV gene transcription in the absence of Tat, knockout (KO) of AFF1, AFF4, or both proteins slightly repress this early step of viral transcription. Upon Tat expression, HIV transcription reaches optimal levels despite KO of AFF1 or AFF4 expression. However, double AFF1/AFF4 KO completely diminishes Tat trans-activation. Significantly, our results show that P-TEFb phosphorylates AFF4 and modulates SEC assembly, AFF1/4 dimerization and recruitment to the viral promoter. We conclude that SEC promotes both early steps of HIV transcription in the absence of Tat, as well as elongation of transcription, when Tat is expressed. Significantly, SEC functions are modulated by P-TEFb.
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Affiliation(s)
- Alona Kuzmina
- a The Shraga Segal Department of Microbiology Immunology and Genetics Faculty of Health Sciences , Ben-Gurion University of the Negev , Israel
| | - Simona Krasnopolsky
- a The Shraga Segal Department of Microbiology Immunology and Genetics Faculty of Health Sciences , Ben-Gurion University of the Negev , Israel
| | - Ran Taube
- a The Shraga Segal Department of Microbiology Immunology and Genetics Faculty of Health Sciences , Ben-Gurion University of the Negev , Israel
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35
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Asamitsu K, Hirokawa T, Okamoto T. MD simulation of the Tat/Cyclin T1/CDK9 complex revealing the hidden catalytic cavity within the CDK9 molecule upon Tat binding. PLoS One 2017; 12:e0171727. [PMID: 28178316 PMCID: PMC5298246 DOI: 10.1371/journal.pone.0171727] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 01/24/2017] [Indexed: 02/02/2023] Open
Abstract
In this study, we applied molecular dynamics (MD) simulation to analyze the dynamic behavior of the Tat/CycT1/CDK9 tri-molecular complex and revealed the structural changes of P-TEFb upon Tat binding. We found that Tat could deliberately change the local flexibility of CycT1. Although the structural coordinates of the H1 and H2 helices did not substantially change, H1', H2', and H3' exhibited significant changes en masse. Consequently, the CycT1 residues involved in Tat binding, namely Tat-recognition residues (TRRs), lost their flexibility with the addition of Tat to P-TEFb. In addition, we clarified the structural variation of CDK9 in complex with CycT1 in the presence or absence of Tat. Interestingly, Tat addition significantly reduced the structural variability of the T-loop, thus consolidating the structural integrity of P-TEFb. Finally, we deciphered the formation of the hidden catalytic cavity of CDK9 upon Tat binding. MD simulation revealed that the PITALRE signature sequence of CDK9 flips the inactive kinase cavity of CDK9 into the active form by connecting with Thr186, which is crucial for its activity, thus presumably recruiting the substrate peptide such as the C-terminal domain of RNA pol II. These findings provide vital information for the development of effective novel anti-HIV drugs with CDK9 catalytic activity as the target.
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Grants
- Ministry of Education, Culture, Sports, Science, and Technology "The Platform Project for Supporting Drug Discovery and Life Science Research (Platform for Drug Discovery, Informatics, and Structural Life Science)"
- Ministry of Education, Culture, Sports, Science, and Technology
- Asahi Grass Foundation
- Japan Agency for Medical Research and Development
- Junwakai Foundation
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Affiliation(s)
- Kaori Asamitsu
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
| | - Takatsugu Hirokawa
- Molecular Profiling Research Center for Drug Discovery (molprof), National Institute of Advanced Industrial Science and Technology (AIST), Tokyo, Japan
- Division of Biomedical Science, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
- * E-mail: (TH); (TO)
| | - Takashi Okamoto
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan
- * E-mail: (TH); (TO)
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36
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Schulze-Gahmen U, Echeverria I, Stjepanovic G, Bai Y, Lu H, Schneidman-Duhovny D, Doudna JA, Zhou Q, Sali A, Hurley JH. Insights into HIV-1 proviral transcription from integrative structure and dynamics of the Tat:AFF4:P-TEFb:TAR complex. eLife 2016; 5. [PMID: 27731797 PMCID: PMC5072841 DOI: 10.7554/elife.15910] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 10/07/2016] [Indexed: 01/04/2023] Open
Abstract
HIV-1 Tat hijacks the human superelongation complex (SEC) to promote proviral transcription. Here we report the 5.9 Å structure of HIV-1 TAR in complex with HIV-1 Tat and human AFF4, CDK9, and CycT1. The TAR central loop contacts the CycT1 Tat-TAR recognition motif (TRM) and the second Tat Zn2+-binding loop. Hydrogen-deuterium exchange (HDX) shows that AFF4 helix 2 is stabilized in the TAR complex despite not touching the RNA, explaining how it enhances TAR binding to the SEC 50-fold. RNA SHAPE and SAXS data were used to help model the extended (Tat Arginine-Rich Motif) ARM, which enters the TAR major groove between the bulge and the central loop. The structure and functional assays collectively support an integrative structure and a bipartite binding model, wherein the TAR central loop engages the CycT1 TRM and compact core of Tat, while the TAR major groove interacts with the extended Tat ARM. DOI:http://dx.doi.org/10.7554/eLife.15910.001
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Affiliation(s)
- Ursula Schulze-Gahmen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Ignacia Echeverria
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.,California Institute of Quantitative Biosciences, University of California San, Francisco, San Francisco, United States
| | - Goran Stjepanovic
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, United States.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States
| | - Yun Bai
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Huasong Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Dina Schneidman-Duhovny
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.,California Institute of Quantitative Biosciences, University of California San, Francisco, San Francisco, United States
| | - Jennifer A Doudna
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, United States.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States.,Department of Chemistry, University of California, Berkeley, Berkeley, United States
| | - Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, United States
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, United States.,Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, United States.,California Institute of Quantitative Biosciences, University of California San, Francisco, San Francisco, United States
| | - James H Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,California Institute of Quantitative Biosciences, University of California, Berkeley, Berkeley, United States.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States
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37
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Okuda H, Takahashi S, Takaori-Kondo A, Yokoyama A. TBP loading by AF4 through SL1 is the major rate-limiting step in MLL fusion-dependent transcription. Cell Cycle 2016; 15:2712-22. [PMID: 27564129 DOI: 10.1080/15384101.2016.1222337] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Gene rearrangement of the mixed lineage leukemia (MLL) gene causes leukemia by inducing the constitutive expression of a gene subset normally expressed only in the immature haematopoietic progenitor cells. MLL gene rearrangements often generate fusion products of MLL and a component of the AF4 family/ENL family/P-TEFb (AEP) complex. MLL-AEP fusion proteins have the potential of constitutively recruiting the P-TEFb elongation complex. Thus, it is hypothesized that relieving the promoter proximal pausing of RNA polymerase II is the rate-limiting step of MLL fusion-dependent transcription. AEP also has the potential to recruit the mediator complex via MED26. We recently showed that AEP activates transcription initiation by facilitating TBP loading to the TATA element through the SL1 complex. In the present study, we show that the key activity responsible for the oncogenic property of MLL-AEP fusion proteins is the TBP loading activity, and not the mediator recruitment or transcriptional elongation activities. Thus, we propose that TBP loading by AF4 through SL1 is the major rate-limiting step in MLL fusion-dependent transcription.
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Affiliation(s)
- Hiroshi Okuda
- a Laboratory for Malignancy Control Research , Kyoto University Graduate School of Medicine , Kyoto , Japan
| | - Satoshi Takahashi
- b Department of Hematology and Oncology , Graduate School of Medicine , Kyoto , Japan
| | - Akifumi Takaori-Kondo
- b Department of Hematology and Oncology , Graduate School of Medicine , Kyoto , Japan
| | - Akihiko Yokoyama
- a Laboratory for Malignancy Control Research , Kyoto University Graduate School of Medicine , Kyoto , Japan.,b Department of Hematology and Oncology , Graduate School of Medicine , Kyoto , Japan
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38
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Vos SM, Pöllmann D, Caizzi L, Hofmann KB, Rombaut P, Zimniak T, Herzog F, Cramer P. Architecture and RNA binding of the human negative elongation factor. eLife 2016; 5. [PMID: 27282391 PMCID: PMC4940160 DOI: 10.7554/elife.14981] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 06/09/2016] [Indexed: 11/30/2022] Open
Abstract
Transcription regulation in metazoans often involves promoter-proximal pausing of RNA polymerase (Pol) II, which requires the 4-subunit negative elongation factor (NELF). Here we discern the functional architecture of human NELF through X-ray crystallography, protein crosslinking, biochemical assays, and RNA crosslinking in cells. We identify a NELF core subcomplex formed by conserved regions in subunits NELF-A and NELF-C, and resolve its crystal structure. The NELF-AC subcomplex binds single-stranded nucleic acids in vitro, and NELF-C associates with RNA in vivo. A positively charged face of NELF-AC is involved in RNA binding, whereas the opposite face of the NELF-AC subcomplex binds NELF-B. NELF-B is predicted to form a HEAT repeat fold, also binds RNA in vivo, and anchors the subunit NELF-E, which is confirmed to bind RNA in vivo. These results reveal the three-dimensional architecture and three RNA-binding faces of NELF. DOI:http://dx.doi.org/10.7554/eLife.14981.001
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Affiliation(s)
- Seychelle M Vos
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - David Pöllmann
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.,Gene Center Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Livia Caizzi
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Katharina B Hofmann
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Pascaline Rombaut
- Gene Center Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Tomasz Zimniak
- Gene Center Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Franz Herzog
- Gene Center Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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39
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Asamitsu K, Omagari K, Okuda T, Hibi Y, Okamoto T. Quantification of the HIV transcriptional activator complex in live cells by image-based protein-protein interaction analysis. Genes Cells 2016; 21:706-16. [PMID: 27193293 DOI: 10.1111/gtc.12375] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 04/17/2016] [Indexed: 01/16/2023]
Abstract
The virus-encoded Tat protein is essential for HIV transcription in infected cells. The interaction of Tat with the cellular transcription elongation factor P-TEFb (positive transcriptional elongation factor b) containing cyclin T1 (CycT1) and cyclin-dependent kinase 9 (CDK9) is critical for its activity. In this study, we use the Fluoppi (fluorescent-based technology detecting protein-protein interaction) system, which enables the quantification of interactions between biomolecules, such as proteins, in live cells. Quantitative measurement of the molecular interactions among Tat, CycT1 and CDK9 has showed that any third molecule enhances the binding between the other two molecules. These findings suggest that each component of the Tat:P-TEFb complex stabilizes the overall complex, thereby supporting the efficient transcriptional elongation during viral RNA synthesis. These interactions may serve as appropriate targets for novel anti-HIV therapy.
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Affiliation(s)
- Kaori Asamitsu
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, 467-8601, Japan
| | - Katsumi Omagari
- Department of Virology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, 467-8601, Japan
| | - Tomoya Okuda
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, 467-8601, Japan
| | - Yurina Hibi
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, 467-8601, Japan
| | - Takashi Okamoto
- Department of Molecular and Cellular Biology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, 467-8601, Japan
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40
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Tyagi M, Weber J, Bukrinsky M, Simon GL. The effects of cocaine on HIV transcription. J Neurovirol 2015; 22:261-74. [PMID: 26572787 DOI: 10.1007/s13365-015-0398-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 10/01/2015] [Accepted: 10/21/2015] [Indexed: 11/29/2022]
Abstract
Illicit drug users are a high-risk population for infection with the human immunodeficiency virus (HIV). A strong correlation exists between prohibited drug use and an increased rate of HIV transmission. Cocaine stands out as one of the most frequently abused illicit drugs, and its use is correlated with HIV infection and disease progression. The central nervous system (CNS) is a common target for both drugs of abuse and HIV, and cocaine intake further accelerates neuronal injury in HIV patients. Although the high incidence of HIV infection in illicit drug abusers is primarily due to high-risk activities such as needle sharing and unprotected sex, several studies have demonstrated that cocaine enhances the rate of HIV gene expression and replication by activating various signal transduction pathways and downstream transcription factors. In order to generate mature HIV genomic transcript, HIV gene expression has to pass through both the initiation and elongation phases of transcription, which requires discrete transcription factors. In this review, we will provide a detailed analysis of the molecular mechanisms that regulate HIV transcription and discuss how cocaine modulates those mechanisms to upregulate HIV transcription and eventually HIV replication.
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Affiliation(s)
- Mudit Tyagi
- Division of Infectious Diseases, Department of Medicine, The George Washington University, 2300 Eye Street, N.W., Washington, DC, 20037, USA. .,Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC, 20037, USA.
| | - Jaime Weber
- Division of Infectious Diseases, Department of Medicine, The George Washington University, 2300 Eye Street, N.W., Washington, DC, 20037, USA
| | - Michael Bukrinsky
- Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Washington, DC, 20037, USA
| | - Gary L Simon
- Division of Infectious Diseases, Department of Medicine, The George Washington University, 2300 Eye Street, N.W., Washington, DC, 20037, USA
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41
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Liu X, Kraus WL, Bai X. Ready, pause, go: regulation of RNA polymerase II pausing and release by cellular signaling pathways. Trends Biochem Sci 2015; 40:516-25. [PMID: 26254229 DOI: 10.1016/j.tibs.2015.07.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Revised: 06/07/2015] [Accepted: 07/06/2015] [Indexed: 01/06/2023]
Abstract
Promoter-proximal pausing by RNA polymerase II (Pol II) is a well-established mechanism to control the timing, rate, and possibly the magnitude of transcriptional responses. Recent studies have shown that cellular signaling pathways can regulate gene transcription and signaling outcomes by controlling Pol II pausing in a wide array of biological systems. Identification of the proteins and small molecules that affect the establishment and release of paused Pol II is shedding new light on the mechanisms and biology of Pol II pausing. This review focuses on the interplay between cellular signaling pathways and Pol II pausing during normal development and under disease conditions.
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Affiliation(s)
- Xiuli Liu
- Molecular Genetics of Blood Development Laboratory, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center at Dallas, TX 75390, USA; Division of Basic Reproductive Biology Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - W Lee Kraus
- Signaling and Gene Regulation Laboratory, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center at Dallas, TX 75390, USA; Division of Basic Reproductive Biology Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Xiaoying Bai
- Molecular Genetics of Blood Development Laboratory, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center at Dallas, TX 75390, USA; Division of Basic Reproductive Biology Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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42
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Lu H, Xue Y, Xue Y, Yu GK, Arias C, Lin J, Fong S, Faure M, Weisburd B, Ji X, Mercier A, Sutton J, Luo K, Gao Z, Zhou Q. Compensatory induction of MYC expression by sustained CDK9 inhibition via a BRD4-dependent mechanism. eLife 2015; 4:e06535. [PMID: 26083714 PMCID: PMC4490784 DOI: 10.7554/elife.06535] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 06/16/2015] [Indexed: 12/22/2022] Open
Abstract
CDK9 is the kinase subunit of positive transcription elongation factor b (P-TEFb) that enables RNA polymerase (Pol) II's transition from promoter-proximal pausing to productive elongation. Although considerable interest exists in CDK9 as a therapeutic target, little progress has been made due to lack of highly selective inhibitors. Here, we describe the development of i-CDK9 as such an inhibitor that potently suppresses CDK9 phosphorylation of substrates and causes genome-wide Pol II pausing. While most genes experience reduced expression, MYC and other primary response genes increase expression upon sustained i-CDK9 treatment. Essential for this increase, the bromodomain protein BRD4 captures P-TEFb from 7SK snRNP to deliver to target genes and also enhances CDK9's activity and resistance to inhibition. Because the i-CDK9-induced MYC expression and binding to P-TEFb compensate for P-TEFb's loss of activity, only simultaneously inhibiting CDK9 and MYC/BRD4 can efficiently induce growth arrest and apoptosis of cancer cells, suggesting the potential of a combinatorial treatment strategy.
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Affiliation(s)
- Huasong Lu
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | | | - Yuahua Xue
- Innovation Center of Cell Signaling Network, School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Guoying K Yu
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Carolina Arias
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Julie Lin
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Susan Fong
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Michel Faure
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Ben Weisburd
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Xiaodan Ji
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Alexandre Mercier
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - James Sutton
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Kunxin Luo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Zhenhai Gao
- Novartis Institute for BioMedical Research, Emeryville, United States
| | - Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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Lu H, Li Z, Zhang W, Schulze-Gahmen U, Xue Y, Zhou Q. Gene target specificity of the Super Elongation Complex (SEC) family: how HIV-1 Tat employs selected SEC members to activate viral transcription. Nucleic Acids Res 2015; 43:5868-79. [PMID: 26007649 PMCID: PMC4499153 DOI: 10.1093/nar/gkv541] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Accepted: 05/11/2015] [Indexed: 01/23/2023] Open
Abstract
The AF4/FMR2 proteins AFF1 and AFF4 act as a scaffold to assemble the Super Elongation Complex (SEC) that strongly activates transcriptional elongation of HIV-1 and cellular genes. Although they can dimerize, it is unclear whether the dimers exist and function within a SEC in vivo. Furthermore, it is unknown whether AFF1 and AFF4 function similarly in mediating SEC-dependent activation of diverse genes. Providing answers to these questions, our current study shows that AFF1 and AFF4 reside in separate SECs that display largely distinct gene target specificities. While the AFF1-SEC is more potent in supporting HIV-1 transactivation by the viral Tat protein, the AFF4-SEC is more important for HSP70 induction upon heat shock. The functional difference between AFF1 and AFF4 in Tat-transactivation has been traced to a single amino acid variation between the two proteins, which causes them to enhance the affinity of Tat for P-TEFb, a key SEC component, with different efficiency. Finally, genome-wide analysis confirms that the genes regulated by AFF1-SEC and AFF4-SEC are largely non-overlapping and perform distinct functions. Thus, the SEC represents a family of related complexes that exist to increase the regulatory diversity and gene control options during transactivation of diverse cellular and viral genes.
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Affiliation(s)
- Huasong Lu
- Innovation Center of Cell Signaling Network, School of Pharmaceutical Sciences, Xiamen University, Xiamen 361005, Fujian, China Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Zichong Li
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Wei Zhang
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ursula Schulze-Gahmen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Yuhua Xue
- Innovation Center of Cell Signaling Network, School of Pharmaceutical Sciences, Xiamen University, Xiamen 361005, Fujian, China
| | - Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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Jin HX, Go ML, Yin P, Qiu XT, Zhu P, Yan XJ. Determining the Functions of HIV-1 Tat and a Second Magnesium Ion in the CDK9/Cyclin T1 Complex: A Molecular Dynamics Simulation Study. PLoS One 2015; 10:e0124673. [PMID: 25909811 PMCID: PMC4409394 DOI: 10.1371/journal.pone.0124673] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 03/16/2015] [Indexed: 11/18/2022] Open
Abstract
The current paradigm of cyclin-dependent kinase (CDK) regulation based on the well-established CDK2 has been recently expanded. The determination of CDK9 crystal structures suggests the requirement of an additional regulatory protein, such as human immunodeficiency virus type 1 (HIV-1) Tat, to exert its physiological functions. In most kinases, the exact number and roles of the cofactor metal ions remain unappreciated, and the repertoire has thus gained increasing attention recently. Here, molecular dynamics (MD) simulations were implemented on CDK9 to explore the functional roles of HIV-1 Tat and the second Mg2+ ion at site 1 (Mg12+). The simulations unveiled that binding of HIV-1 Tat to CDK9 not only stabilized hydrogen bonds (H-bonds) between ATP and hinge residues Asp104 and Cys106, as well as between ATP and invariant Lys48, but also facilitated the salt bridge network pertaining to the phosphorylated Thr186 at the activation loop. By contrast, these H-bonds cannot be formed in CDK9 owing to the absence of HIV-1 Tat. MD simulations further revealed that the Mg12+ ion, coupled with the Mg22+ ion, anchored to the triphosphate moiety of ATP in its catalytic competent conformation. This observation indicates the requirement of the Mg12+ ion for CDK9 to realize its function. Overall, the introduction of HIV-1 Tat and Mg12+ ion resulted in the active site architectural characteristics of phosphorylated CDK9. These data highlighted the functional roles of HIV-1 Tat and Mg12+ ion in the regulation of CDK9 activity, which contributes an important complementary understanding of CDK molecular underpinnings.
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Affiliation(s)
- Hai-Xiao Jin
- Key Laboratory of Applied Marine Biotechnology Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, China
| | - Mei-Lin Go
- Department of Pharmacy, National University of Singapore, Singapore, Singapore
| | - Peng Yin
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, China
| | - Xiao-Ting Qiu
- Key Laboratory of Applied Marine Biotechnology Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, China
| | - Peng Zhu
- Key Laboratory of Applied Marine Biotechnology Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, China
| | - Xiao-Jun Yan
- Key Laboratory of Applied Marine Biotechnology Ministry of Education, School of Marine Sciences, Ningbo University, Ningbo, China
- * E-mail:
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Chen Y, Zhang L, Estarás C, Choi SH, Moreno L, Karn J, Moresco JJ, Yates JR, Jones KA. A gene-specific role for the Ssu72 RNAPII CTD phosphatase in HIV-1 Tat transactivation. Genes Dev 2014; 28:2261-75. [PMID: 25319827 PMCID: PMC4201287 DOI: 10.1101/gad.250449.114] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
HIV-1 Tat stimulates transcription elongation by recruiting the P-TEFb (positive transcription elongation factor-b) (CycT1:CDK9) C-terminal domain (CTD) kinase to the HIV-1 promoter. Here we show that Tat transactivation also requires the Ssu72 CTD Ser5P (S5P)-specific phosphatase, which mediates transcription termination and intragenic looping at eukaryotic genes. Importantly, HIV-1 Tat interacts directly with Ssu72 and strongly stimulates its CTD phosphatase activity. We found that Ssu72 is essential for Tat:P-TEFb-mediated phosphorylation of the S5P-CTD in vitro. Interestingly, Ssu72 also stimulates nascent HIV-1 transcription in a phosphatase-dependent manner in vivo. Chromatin immunoprecipitation (ChIP) experiments reveal that Ssu72, like P-TEFb and AFF4, is recruited by Tat to the integrated HIV-1 proviral promoter in TNF-α signaling 2D10 T cells and leaves the elongation complex prior to the termination site. ChIP-seq (ChIP combined with deep sequencing) and GRO-seq (genome-wide nuclear run-on [GRO] combined with deep sequencing) analysis further reveals that Ssu72 predominantly colocalizes with S5P-RNAPII (RNA polymerase II) at promoters in human embryonic stem cells, with a minor peak in the terminator region. A few genes, like NANOG, also have high Ssu72 at the terminator. Ssu72 is not required for transcription at most cellular genes but has a modest effect on cotranscriptional termination. We conclude that Tat alters the cellular function of Ssu72 to stimulate viral gene expression and facilitate the early S5P-S2P transition at the integrated HIV-1 promoter.
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Affiliation(s)
- Yupeng Chen
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Lirong Zhang
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Conchi Estarás
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Seung H Choi
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Luis Moreno
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - James J Moresco
- Department of Chemical Physiology and Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - John R Yates
- Department of Chemical Physiology and Cell Biology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Katherine A Jones
- Regulatory Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037, USA;
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