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Palumbo RJ, Yang Y, Feigon J, Hanes SD. Catalytic activity of the Bin3/MePCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. Genetics 2024; 226:iyad203. [PMID: 37982586 PMCID: PMC10763541 DOI: 10.1093/genetics/iyad203] [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: 05/31/2023] [Revised: 10/27/2023] [Accepted: 11/13/2023] [Indexed: 11/21/2023] Open
Abstract
Methylphosphate Capping Enzyme (MePCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MePCE in vitro, little is known about its functions in vivo, or what roles-if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MePCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MePCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MePCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
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Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Yuan Yang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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2
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Yapo V, Majumder K, Tedbury PR, Wen X, Ong YT, Johnson MC, Sarafianos SG. HIV-2 inhibits HIV-1 gene expression via two independent mechanisms during cellular co-infection. J Virol 2023; 97:e0187022. [PMID: 37991365 PMCID: PMC10734542 DOI: 10.1128/jvi.01870-22] [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: 12/16/2022] [Accepted: 06/28/2023] [Indexed: 11/23/2023] Open
Abstract
IMPORTANCE Twenty-five years after the first report that HIV-2 infection can reduce HIV-1-associated pathogenesis in dual-infected patients, the mechanisms are still not well understood. We explored these mechanisms in cell culture and showed first that these viruses can co-infect individual cells. Under specific conditions, HIV-2 inhibits HIV-1 through two distinct mechanisms, a broad-spectrum interferon response and an HIV-1-specific inhibition conferred by the HIV-2 TAR. The former could play a prominent role in dually infected individuals, whereas the latter targets HIV-1 promoter activity through competition for HIV-1 Tat binding when the same target cell is dually infected. That mechanism suppresses HIV-1 transcription by stalling RNA polymerase II complexes at the promoter through a minimal inhibitory region within the HIV-2 TAR. This work delineates the sequence of appearance and the modus operandi of each mechanism.
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Affiliation(s)
- Vincent Yapo
- CS Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Kinjal Majumder
- CS Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Philip R. Tedbury
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Xin Wen
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Yee T. Ong
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Marc C. Johnson
- CS Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
- Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, Missouri, USA
| | - Stefan G. Sarafianos
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
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3
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Gaur T, Poddutoori R, Khare L, Bagal B, Rashmi S, Patkar N, Tembhare P, Pg S, Shetty D, Dutt A, Zhang Q, Konopleva M, Platzbeckar U, Gupta S, Samajdar S, Ramchandra M, Khattry N, Hasan SK. Novel covalent CDK7 inhibitor potently induces apoptosis in acute myeloid leukemia and synergizes with Venetoclax. J Exp Clin Cancer Res 2023; 42:186. [PMID: 37507802 PMCID: PMC10386772 DOI: 10.1186/s13046-023-02750-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023] Open
Abstract
INTRODUCTION The emergence of resistance to the highly successful BCL2-directed therapy is a major unmet need in acute myeloid leukemia (AML), an aggressive malignancy with poor survival rates. Towards identifying therapeutic options for AML patients who progress on BCL2-directed therapy, we studied a clinical-stage CDK7 inhibitor XL102, which is being evaluated in solid tumors (NCT04726332). MATERIALS AND METHODS To determine the anti-proliferative effects of XL102, we performed experiments including time-resolved fluorescence resonance energy transfer, target occupancy, cell cycle and apoptosis-based assays. We also included genetically characterized primary myeloid blasts from de novo and relapsed/refractory AML patients. For mechanistic studies, CRISPR/Cas9 mediated knockout of CDK7 and c-Myc and immunoblotting were performed. NOD/SCID orthotropic and subcutaneous AML xenografts were used to determine anti-leukemic effects. To assess the synergistic effects of XL102 with Venetoclax, we performed RNA sequencing and gene set enrichment analysis using Venetoclax sensitive and resistant model systems. RESULTS XL102, a highly specific, orally bioavailable covalent inhibitor of CDK7. Inhibitory effect on CDK7 by XL102 in primary myeloid blasts (n = 54) was in nanomolar range (mean = 300 nM; range = 4.0-952 nM). XL102 treated AML cells showed a reduction in phosphorylation levels of Serine 2/5/7 at carboxy-terminal domain of RNA polymerase II. T-loop phosphorylation of CDK1(Thr161) and CDK2(Thr160) was inhibited by XL102 in dose-dependent manner leading to cell-cycle arrest. c-Myc downregulation and enhanced levels of p53 and p21 in XL102 treated cells were observed. Increased levels of p21 and activation of p53 by XL102 were mimicked by genetic ablation of CDK7, which supports that the observed effects of XL102 are due to CDK7 inhibition. XL102 treated AML xenografts showed remarkable reduction in hCD45 + marrow cells (mean = 0.60%; range = 0.04%-3.53%) compared to vehicle control (mean = 38.2%; range = 10.1%-78%), with corresponding increase in p53, p21 and decrease in c-Myc levels. The data suggests XL102 induces apoptosis in AML cells via CDK7/c-Myc/p53 axis. RNA-sequencing from paired Venetoclax-sensitive and Venetoclax-resistant cells treated with XL102 showed downregulation of genes involved in proliferation and apoptosis. CONCLUSION Taken together, XL102 with Venetoclax led to synergistic effects in overcoming resistance and provided a strong rationale for clinical evaluation of XL102 as a single agent and in combination with Venetoclax.
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Affiliation(s)
- Tarang Gaur
- Hasan Lab, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
| | - Ramulu Poddutoori
- Aurigene Oncology Limited, Electronic City Hosur Road, Bangalore, 560100, India
| | - Leena Khare
- Aurigene Oncology Limited, Electronic City Hosur Road, Bangalore, 560100, India
| | - Bhausaheb Bagal
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
- Department of Medical Oncology, Tata Memorial Hospital, Tata Memorial Centre, Mumbai, 400014, India
| | - Sonal Rashmi
- Dutt Lab, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India
- Present Address: CNAG-CRG, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Nikhil Patkar
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
- Hematopathology Laboratory, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India
| | - Prashant Tembhare
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
- Hematopathology Laboratory, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India
| | - Subramanian Pg
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
- Hematopathology Laboratory, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India
| | - Dhanlaxmi Shetty
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
- Department of Cytogenetics, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India
| | - Amit Dutt
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
- Dutt Lab, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India
| | - Qi Zhang
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | | | - Uwe Platzbeckar
- Medical Clinic and Policlinic I, Hematology and Cellular Therapy, University Hospital Leipzig, Johannisallee 32, 04103, Leipzig, Germany
| | - Sudeep Gupta
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India
- Department of Medical Oncology, Tata Memorial Hospital, Tata Memorial Centre, Mumbai, 400014, India
| | - Susanta Samajdar
- Aurigene Oncology Limited, Electronic City Hosur Road, Bangalore, 560100, India
| | - Murali Ramchandra
- Aurigene Oncology Limited, Electronic City Hosur Road, Bangalore, 560100, India
| | - Navin Khattry
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India.
- Department of Medical Oncology, Tata Memorial Hospital, Tata Memorial Centre, Mumbai, 400014, India.
| | - Syed K Hasan
- Hasan Lab, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), Tata Memorial Centre, Navi, Mumbai, 410210, India.
- Homi Bhabha National Institute (HBNI), Anushaktinagar, Mumbai, 400094, India.
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Palumbo RJ, Hanes SD. Catalytic activity of the Bin3/MEPCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543302. [PMID: 37333392 PMCID: PMC10274667 DOI: 10.1101/2023.06.01.543302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Methylphosphate Capping Enzyme (MEPCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MEPCE in vitro, little is known about its functions in vivo, or what roles- if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MEPCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MEPCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MEPCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
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Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
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Wang L, Xu L, Wang Z, Hou T, Hao H, Sun H. Cooperation of structural motifs controls drug selectivity in cyclin-dependent kinases: an advanced theoretical analysis. Brief Bioinform 2023; 24:6964518. [PMID: 36578163 DOI: 10.1093/bib/bbac544] [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: 08/01/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 12/30/2022] Open
Abstract
Understanding drug selectivity mechanism is a long-standing issue for helping design drugs with high specificity. Designing drugs targeting cyclin-dependent kinases (CDKs) with high selectivity is challenging because of their highly conserved binding pockets. To reveal the underlying general selectivity mechanism, we carried out comprehensive analyses from both the thermodynamics and kinetics points of view on a representative CDK12 inhibitor. To fully capture the binding features of the drug-target recognition process, we proposed to use kinetic residue energy analysis (KREA) in conjunction with the community network analysis (CNA) to reveal the underlying cooperation effect between individual residues/protein motifs to the binding/dissociating process of the ligand. The general mechanism of drug selectivity in CDKs can be summarized as that the difference of structural cooperation between the ligand and the protein motifs leads to the difference of the energetic contribution of the key residues to the ligand. The proposed mechanisms may be prevalent in drug selectivity issues, and the insights may help design new strategies to overcome/attenuate the drug selectivity associated problems.
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Affiliation(s)
- Lingling Wang
- Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing 210009, Jiangsu, P. R. China
| | - Lei Xu
- Institute of Bioinformatics and Medical Engineering, Jiangsu University of Technology, Changzhou 213001, Jiangsu, P. R. China
| | - Zhe Wang
- Innovation Institute for Artificial Intelligence in Medicine of Zhejiang University, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, Zhejiang, P. R. China
| | | | - Haiping Hao
- State Key Laboratory of Natural Medicines, Key Lab of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, 210009 Nanjing, China
| | - Huiyong Sun
- Department of Medicinal Chemistry, China Pharmaceutical University, Nanjing 210009, Jiangsu, P. R. China
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6
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Kumar V, Parate S, Thakur G, Lee G, Ro HS, Kim Y, Kim HJ, Kim MO, Lee KW. Identification of CDK7 Inhibitors from Natural Sources Using Pharmacoinformatics and Molecular Dynamics Simulations. Biomedicines 2021; 9:1197. [PMID: 34572383 PMCID: PMC8468199 DOI: 10.3390/biomedicines9091197] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 02/02/2023] Open
Abstract
The cyclin-dependent kinase 7 (CDK7) plays a crucial role in regulating the cell cycle and RNA polymerase-based transcription. Overexpression of this kinase is linked with various cancers in humans due to its dual involvement in cell development. Furthermore, emerging evidence has revealed that inhibiting CDK7 has anti-cancer effects, driving the development of novel and more cost-effective inhibitors with enhanced selectivity for CDK7 over other CDKs. In the present investigation, a pharmacophore-based approach was utilized to identify potential hit compounds against CDK7. The generated pharmacophore models were validated and used as 3D queries to screen 55,578 natural drug-like compounds. The obtained compounds were then subjected to molecular docking and molecular dynamics simulations to predict their binding mode with CDK7. The molecular dynamics simulation trajectories were subsequently used to calculate binding affinity, revealing four hits-ZINC20392430, SN00112175, SN00004718, and SN00262261-having a better binding affinity towards CDK7 than the reference inhibitors (CT7001 and THZ1). The binding mode analysis displayed hydrogen bond interactions with the hinge region residues Met94 and Glu95, DFG motif residue Asp155, ATP-binding site residues Thr96, Asp97, and Gln141, and quintessential residue outside the kinase domain, Cys312 of CDK7. The in silico selectivity of the hits was further checked by docking with CDK2, the close homolog structure of CDK7. Additionally, the detailed pharmacokinetic properties were predicted, revealing that our hits have better properties than established CDK7 inhibitors CT7001 and THZ1. Hence, we argue that proposed hits may be crucial against CDK7-related malignancies.
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Affiliation(s)
- Vikas Kumar
- Department of Bio & Medical Big Data (BK4 Program), Division of Life Sciences, Research Institute of Natural Science (RINS), Gyeongsang National University (GNU), 501 Jinju-daero, Jinju 52828, Korea;
| | - Shraddha Parate
- Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Division of Applied Life Science, Gyeongsang National University (GNU), 501 Jinju-daero, Jinju 52828, Korea; (S.P.); (G.L.)
| | - Gunjan Thakur
- Department of Veterinary Medicine, Institute of Animal Medicine, Gyeongsang National University (GNU), Jinju 52828, Korea;
| | - Gihwan Lee
- Plant Molecular Biology and Biotechnology Research Center (PMBBRC), Division of Applied Life Science, Gyeongsang National University (GNU), 501 Jinju-daero, Jinju 52828, Korea; (S.P.); (G.L.)
| | - Hyeon-Su Ro
- Department of Bio & Medical Big Data (BK4 Program), Research Institute of Life Sciences, Gyeongsang National University (GNU), Jinju 52828, Korea;
| | - Yongseong Kim
- School of Cosmetics and Food Development, Kyungnam University, Masan 631-701, Korea;
| | - Hong Ja Kim
- Division of Life Sciences and Applied Life Science (BK21 Four), Research Institute of Natural Science (RINS), Gyeongsang National University (GNU), 501 Jinju-daero, Jinju 52828, Korea;
| | - Myeong Ok Kim
- Division of Life Sciences and Applied Life Science (BK21 Four), Research Institute of Natural Science (RINS), Gyeongsang National University (GNU), 501 Jinju-daero, Jinju 52828, Korea;
| | - Keun Woo Lee
- Department of Bio & Medical Big Data (BK4 Program), Division of Life Sciences, Research Institute of Natural Science (RINS), Gyeongsang National University (GNU), 501 Jinju-daero, Jinju 52828, Korea;
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7
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Jiang B, Gao Y, Che J, Lu W, Kaltheuner IH, Dries R, Kalocsay M, Berberich MJ, Jiang J, You I, Kwiatkowski N, Riching KM, Daniels DL, Sorger PK, Geyer M, Zhang T, Gray NS. Discovery and resistance mechanism of a selective CDK12 degrader. Nat Chem Biol 2021; 17:675-683. [PMID: 33753926 PMCID: PMC8590456 DOI: 10.1038/s41589-021-00765-y] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 01/09/2021] [Accepted: 02/04/2021] [Indexed: 01/31/2023]
Abstract
Cyclin-dependent kinase 12 (CDK12) is an emerging therapeutic target due to its role in regulating transcription of DNA-damage response (DDR) genes. However, development of selective small molecules targeting CDK12 has been challenging due to the high degree of homology between kinase domains of CDK12 and other transcriptional CDKs, most notably CDK13. In the present study, we report the rational design and characterization of a CDK12-specific degrader, BSJ-4-116. BSJ-4-116 selectively degraded CDK12 as assessed through quantitative proteomics. Selective degradation of CDK12 resulted in premature cleavage and poly(adenylation) of DDR genes. Moreover, BSJ-4-116 exhibited potent antiproliferative effects, alone and in combination with the poly(ADP-ribose) polymerase inhibitor olaparib, as well as when used as a single agent against cell lines resistant to covalent CDK12 inhibitors. Two point mutations in CDK12 were identified that confer resistance to BSJ-4-116, demonstrating a potential mechanism that tumor cells can use to evade bivalent degrader molecules.
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Affiliation(s)
- Baishan Jiang
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.,These authors contributed equally: Baishan Jiang, Yang Gao and Jianwei Che
| | - Yang Gao
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.,These authors contributed equally: Baishan Jiang, Yang Gao and Jianwei Che
| | - Jianwei Che
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.,These authors contributed equally: Baishan Jiang, Yang Gao and Jianwei Che
| | - Wenchao Lu
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | | | - Ruben Dries
- Department of Hematology and Oncology, Boston University, Boston, Massachusetts, USA.,Department of Computational Medicine, Boston University, Boston, Massachusetts, USA
| | - Marian Kalocsay
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew J. Berberich
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Jie Jiang
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Inchul You
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Nicholas Kwiatkowski
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | | | | | - Peter K. Sorger
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthias Geyer
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Tinghu Zhang
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.,Correspondence should be addressed to Tinghu Zhang (); Nathanael S. Gray ()
| | - Nathanael S. Gray
- Department of Cancer Biology, Dana–Farber Cancer Institute, Boston, Massachusetts, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts, USA.,Correspondence should be addressed to Tinghu Zhang (); Nathanael S. Gray ()
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8
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Shukla A, Ramirez NGP, D’Orso I. HIV-1 Proviral Transcription and Latency in the New Era. Viruses 2020; 12:v12050555. [PMID: 32443452 PMCID: PMC7291205 DOI: 10.3390/v12050555] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Revised: 05/06/2020] [Accepted: 05/12/2020] [Indexed: 12/11/2022] Open
Abstract
Three decades of extensive work in the HIV field have revealed key viral and host cell factors controlling proviral transcription. Various models of transcriptional regulation have emerged based on the collective information from in vitro assays and work in both immortalized and primary cell-based models. Here, we provide a recount of the past and current literature, highlight key regulatory aspects, and further describe potential limitations of previous studies. We particularly delve into critical steps of HIV gene expression including the role of the integration site, nucleosome positioning and epigenomics, and the transition from initiation to pausing and pause release. We also discuss open questions in the field concerning the generality of previous regulatory models to the control of HIV transcription in patients under suppressive therapy, including the role of the heterogeneous integration landscape, clonal expansion, and bottlenecks to eradicate viral persistence. Finally, we propose that building upon previous discoveries and improved or yet-to-be discovered technologies will unravel molecular mechanisms of latency establishment and reactivation in a “new era”.
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9
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P-TEFb as A Promising Therapeutic Target. Molecules 2020; 25:molecules25040838. [PMID: 32075058 PMCID: PMC7070488 DOI: 10.3390/molecules25040838] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 01/19/2023] Open
Abstract
The positive transcription elongation factor b (P-TEFb) was first identified as a general factor that stimulates transcription elongation by RNA polymerase II (RNAPII), but soon afterwards it turned out to be an essential cellular co-factor of human immunodeficiency virus (HIV) transcription mediated by viral Tat proteins. Studies on the mechanisms of Tat-dependent HIV transcription have led to radical advances in our knowledge regarding the mechanism of eukaryotic transcription, including the discoveries that P-TEFb-mediated elongation control of cellular transcription is a main regulatory step of gene expression in eukaryotes, and deregulation of P-TEFb activity plays critical roles in many human diseases and conditions in addition to HIV/AIDS. P-TEFb is now recognized as an attractive and promising therapeutic target for inflammation/autoimmune diseases, cardiac hypertrophy, cancer, infectious diseases, etc. In this review article, I will summarize our knowledge about basic P-TEFb functions, the regulatory mechanism of P-TEFb-dependent transcription, P-TEFb’s involvement in biological processes and diseases, and current approaches to manipulating P-TEFb functions for the treatment of these diseases.
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10
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Rasool RU, Natesan R, Deng Q, Aras S, Lal P, Sander Effron S, Mitchell-Velasquez E, Posimo JM, Carskadon S, Baca SC, Pomerantz MM, Siddiqui J, Schwartz LE, Lee DJ, Palanisamy N, Narla G, Den RB, Freedman ML, Brady DC, Asangani IA. CDK7 Inhibition Suppresses Castration-Resistant Prostate Cancer through MED1 Inactivation. Cancer Discov 2019; 9:1538-1555. [PMID: 31466944 PMCID: PMC7202356 DOI: 10.1158/2159-8290.cd-19-0189] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 07/09/2019] [Accepted: 08/21/2019] [Indexed: 02/06/2023]
Abstract
Metastatic castration-resistant prostate cancer (CRPC) is a fatal disease, primarily resulting from the transcriptional addiction driven by androgen receptor (AR). First-line CRPC treatments typically target AR signaling, but are rapidly bypassed, resulting in only a modest survival benefit with antiandrogens. Therapeutic approaches that more effectively block the AR-transcriptional axis are urgently needed. Here, we investigated the molecular mechanism underlying the association between the transcriptional coactivator MED1 and AR as a vulnerability in AR-driven CRPC. MED1 undergoes CDK7-dependent phosphorylation at T1457 and physically engages AR at superenhancer sites, and is essential for AR-mediated transcription. In addition, a CDK7-specific inhibitor, THZ1, blunts AR-dependent neoplastic growth by blocking AR/MED1 corecruitment genome-wide, as well as reverses the hyperphosphorylated MED1-associated enzalutamide-resistant phenotype. In vivo, THZ1 induces tumor regression of AR-amplified human CRPC in a xenograft mouse model. Together, we demonstrate that CDK7 inhibition selectively targets MED1-mediated, AR-dependent oncogenic transcriptional amplification, thus representing a potential new approach for the treatment of CRPC. SIGNIFICANCE: Potent inhibition of AR signaling is critical to treat CRPC. This study uncovers a driver role for CDK7 in regulating AR-mediated transcription through phosphorylation of MED1, thus revealing a therapeutically targetable potential vulnerability in AR-addicted CRPC.See related commentary by Russo et al., p. 1490.This article is highlighted in the In This Issue feature, p. 1469.
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Affiliation(s)
- Reyaz Ur Rasool
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Ramakrishnan Natesan
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Qu Deng
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Shweta Aras
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Priti Lal
- Department of Pathology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Samuel Sander Effron
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Erick Mitchell-Velasquez
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jessica M Posimo
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Shannon Carskadon
- Department of Urology, Vattikuti Urology Institute, Henry Ford Health System, Detroit, Michigan
| | - Sylvan C Baca
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
| | - Mark M Pomerantz
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
| | - Javed Siddiqui
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Lauren E Schwartz
- Department of Pathology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Daniel J Lee
- Department of Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Nallasivam Palanisamy
- Department of Urology, Vattikuti Urology Institute, Henry Ford Health System, Detroit, Michigan
| | - Goutham Narla
- Division of Genetic Medicine, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Robert B Den
- Department of Radiation Oncology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Matthew L Freedman
- Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
| | - Donita C Brady
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Irfan A Asangani
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
- Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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11
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Videla-Richardson GA, Furmento VA, Garcia CP, Morris-Hanon O, Sevlever GE, Romorini L, Scassa ME. Human embryonic stem cells display a pronounced sensitivity to the cyclin dependent kinase inhibitor Roscovitine. BMC Mol Cell Biol 2019; 20:40. [PMID: 31462218 PMCID: PMC6712821 DOI: 10.1186/s12860-019-0222-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 08/19/2019] [Indexed: 12/14/2022] Open
Abstract
Background The essentially unlimited expansion potential and the pluripotency of human embryonic stem cells (hESCs) make them attractive for cell-based therapeutic purposes. Although hESCs can indefinitely proliferate in culture, unlike transformed cancer cells, they are endowed with a cell-intrinsic property termed mitochondrial priming that renders them highly sensitive to apoptotic stimuli. Thus, all attempts to broaden the insights into hESCs apoptosis may be helpful for establishing pro-survival strategies valuable for its in vitro culture and further use in clinical applications. Cyclin-dependent kinases (CDKs), a family of serine/threonine protein kinases originally identified as regulators of the eukaryotic cell cycle, can also regulate transcription and differentiation. Moreover, there are compelling data suggesting that its activities are involved in certain apoptotic programs in different cell types. Currently, it is not completely determined whether CDKs regulate apoptotic processes in rapidly proliferating and apoptosis-prone hESCs. In this study, to elucidate the effect of CDKs inhibition in hESCs we used Roscovitine (ROSC), a purine analogue that selectively inhibits the activities of these kinases. Results Inhibition of CDKs by ROSC triggers programmed cell death in hESCs but not in proliferating somatic cells (human fibroblasts). The apoptotic process encompasses caspase-9 and -3 activation followed by PARP cleavage. ROSC treatment also leads to p53 stabilization, which coincides with site-specific phosphorylation at serine 46 and decreased levels of Mdm2. Additionally, we observed a transcriptional induction of p53AIP1, a repression of pro-survival factor Mcl-1 and an up-regulation of pro-apoptotic BH3-only proteins NOXA and PUMA. Importantly, we found that the role of CDK2 inhibition appears to be at best accessory as an active CDK2 is not required to ensure hESCs survival. Conclusion Our experimental data reveal that hESCs, contrary to fibroblasts, exhibit a pronounced sensitivity to ROSC.
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Affiliation(s)
- Guillermo A Videla-Richardson
- Laboratorios de Investigación Aplicada en Neurociencias (LIAN-CONICET), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Belén de Escobar, Provincia de Buenos Aires, Argentina
| | - Verónica A Furmento
- Laboratorios de Investigación Aplicada en Neurociencias (LIAN-CONICET), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Belén de Escobar, Provincia de Buenos Aires, Argentina
| | - Carolina P Garcia
- Laboratorios de Investigación Aplicada en Neurociencias (LIAN-CONICET), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Belén de Escobar, Provincia de Buenos Aires, Argentina
| | - Olivia Morris-Hanon
- Laboratorios de Investigación Aplicada en Neurociencias (LIAN-CONICET), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Belén de Escobar, Provincia de Buenos Aires, Argentina
| | - Gustavo E Sevlever
- Laboratorios de Investigación Aplicada en Neurociencias (LIAN-CONICET), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Belén de Escobar, Provincia de Buenos Aires, Argentina
| | - Leonardo Romorini
- Laboratorios de Investigación Aplicada en Neurociencias (LIAN-CONICET), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Belén de Escobar, Provincia de Buenos Aires, Argentina
| | - María E Scassa
- Laboratorios de Investigación Aplicada en Neurociencias (LIAN-CONICET), Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia (FLENI), Belén de Escobar, Provincia de Buenos Aires, Argentina.
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12
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Krajewska M, Dries R, Grassetti AV, Dust S, Gao Y, Huang H, Sharma B, Day DS, Kwiatkowski N, Pomaville M, Dodd O, Chipumuro E, Zhang T, Greenleaf AL, Yuan GC, Gray NS, Young RA, Geyer M, Gerber SA, George RE. CDK12 loss in cancer cells affects DNA damage response genes through premature cleavage and polyadenylation. Nat Commun 2019; 10:1757. [PMID: 30988284 PMCID: PMC6465371 DOI: 10.1038/s41467-019-09703-y] [Citation(s) in RCA: 143] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 03/26/2019] [Indexed: 02/07/2023] Open
Abstract
Cyclin-dependent kinase 12 (CDK12) modulates transcription elongation by phosphorylating the carboxy-terminal domain of RNA polymerase II and selectively affects the expression of genes involved in the DNA damage response (DDR) and mRNA processing. Yet, the mechanisms underlying such selectivity remain unclear. Here we show that CDK12 inhibition in cancer cells lacking CDK12 mutations results in gene length-dependent elongation defects, inducing premature cleavage and polyadenylation (PCPA) and loss of expression of long (>45 kb) genes, a substantial proportion of which participate in the DDR. This early termination phenotype correlates with an increased number of intronic polyadenylation sites, a feature especially prominent among DDR genes. Phosphoproteomic analysis indicated that CDK12 directly phosphorylates pre-mRNA processing factors, including those regulating PCPA. These results support a model in which DDR genes are uniquely susceptible to CDK12 inhibition primarily due to their relatively longer lengths and lower ratios of U1 snRNP binding to intronic polyadenylation sites. Cdk12 is primarily involved in the regulation of DNA damage response (DDR) gene transcription as well as mRNA processing. Here, the authors demonstrate that CDK12 suppresses intronic polyadenylation, and that inhibition of this kinase primarily affects the expression of long genes with higher numbers of polyA sites, features common to many DDR genes.
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Affiliation(s)
- Malgorzata Krajewska
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Ruben Dries
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.,Departments of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Andrew V Grassetti
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH, 03756, USA
| | - Sofia Dust
- Institute of Structural Biology, University of Bonn, 53127, Bonn, Germany
| | - Yang Gao
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Hao Huang
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA
| | - Bandana Sharma
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA
| | - Daniel S Day
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA, 02142, USA
| | - Nicholas Kwiatkowski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Monica Pomaville
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA
| | - Oliver Dodd
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA
| | - Edmond Chipumuro
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA
| | - Tinghu Zhang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Arno L Greenleaf
- Department of Biochemistry, Duke University Medical Center, Durham, NC, 27710, USA
| | - Guo-Cheng Yuan
- Departments of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.,Harvard School of Public Health, Boston, MA, 02115, USA
| | - Nathanael S Gray
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, 02115, USA
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Massachusetts Institute of Technology, Cambridge, MA, 02142, USA
| | - Matthias Geyer
- Institute of Structural Biology, University of Bonn, 53127, Bonn, Germany
| | - Scott A Gerber
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH, 03756, USA
| | - Rani E George
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, 02115, USA. .,Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
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13
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Marié IJ, Chang HM, Levy DE. HDAC stimulates gene expression through BRD4 availability in response to IFN and in interferonopathies. J Exp Med 2018; 215:3194-3212. [PMID: 30463877 PMCID: PMC6279398 DOI: 10.1084/jem.20180520] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 08/15/2018] [Accepted: 10/19/2018] [Indexed: 01/12/2023] Open
Abstract
In contrast to the common role of histone deacetylases (HDACs) for gene repression, HDAC activity provides a required positive function for IFN-stimulated gene (ISG) expression. Here, we show that HDAC1/2 as components of the Sin3A complex are required for ISG transcriptional elongation but not for recruitment of RNA polymerase or transcriptional initiation. Transcriptional arrest by HDAC inhibition coincides with failure to recruit the epigenetic reader Brd4 and elongation factor P-TEFb due to sequestration of Brd4 on hyperacetylated chromatin. Brd4 availability is regulated by an equilibrium cycle between opposed acetyltransferase and deacetylase activities that maintains a steady-state pool of free Brd4 available for recruitment to inducible promoters. An ISG expression signature is a hallmark of interferonopathies and other autoimmune diseases. Combined inhibition of HDAC1/2 and Brd4 resolved the aberrant ISG expression detected in cells derived from patients with two inherited interferonopathies, ISG15 and USP18 deficiencies, defining a novel therapeutic approach to ISG-associated autoimmune diseases.
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Affiliation(s)
- Isabelle J Marié
- Departments of Pathology and Microbiology and Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - Hao-Ming Chang
- Departments of Pathology and Microbiology and Perlmutter Cancer Center, New York University School of Medicine, New York, NY
| | - David E Levy
- Departments of Pathology and Microbiology and Perlmutter Cancer Center, New York University School of Medicine, New York, NY
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14
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Kalan S, Amat R, Schachter MM, Kwiatkowski N, Abraham BJ, Liang Y, Zhang T, Olson CM, Larochelle S, Young RA, Gray NS, Fisher RP. Activation of the p53 Transcriptional Program Sensitizes Cancer Cells to Cdk7 Inhibitors. Cell Rep 2018; 21:467-481. [PMID: 29020632 DOI: 10.1016/j.celrep.2017.09.056] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 08/21/2017] [Accepted: 09/17/2017] [Indexed: 12/23/2022] Open
Abstract
Cdk7, the CDK-activating kinase and transcription factor IIH component, is a target of inhibitors that kill cancer cells by exploiting tumor-specific transcriptional dependencies. However, whereas selective inhibition of analog-sensitive (AS) Cdk7 in colon cancer-derived cells arrests division and disrupts transcription, it does not by itself trigger apoptosis efficiently. Here, we show that p53 activation by 5-fluorouracil or nutlin-3 synergizes with a reversible Cdk7as inhibitor to induce cell death. Synthetic lethality was recapitulated with covalent inhibitors of wild-type Cdk7, THZ1, or the more selective YKL-1-116. The effects were allele specific; a CDK7as mutation conferred both sensitivity to bulky adenine analogs and resistance to covalent inhibitors. Non-transformed colon epithelial cells were resistant to these combinations, as were cancer-derived cells with p53-inactivating mutations. Apoptosis was dependent on death receptor DR5, a p53 transcriptional target whose expression was refractory to Cdk7 inhibition. Therefore, p53 activation induces transcriptional dependency to sensitize cancer cells to Cdk7 inhibition.
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Affiliation(s)
- Sampada Kalan
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Ramon Amat
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Miriam Merzel Schachter
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Nicholas Kwiatkowski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Brian J Abraham
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA
| | - Yanke Liang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Tinghu Zhang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Calla M Olson
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Stéphane Larochelle
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Richard A Young
- Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, MA 02142, USA
| | - Nathanael S Gray
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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15
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Hall DD, Ponce JM, Chen B, Spitler KM, Alexia A, Oudit GY, Song LS, Grueter CE. Ectopic expression of Cdk8 induces eccentric hypertrophy and heart failure. JCI Insight 2017; 2:92476. [PMID: 28768905 DOI: 10.1172/jci.insight.92476] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 06/20/2017] [Indexed: 11/17/2022] Open
Abstract
Widespread changes in cardiac gene expression occur during heart failure, yet the mechanisms responsible for coordinating these changes remain poorly understood. The Mediator complex represents a nodal point for modulating transcription by bridging chromatin-bound transcription factors with RNA polymerase II activity; it is reversibly regulated by its cyclin-dependent kinase 8 (Cdk8) kinase submodule. Here, we identified increased Cdk8 protein expression in human failing heart explants and determined the consequence of this increase in cardiac-specific Cdk8-expressing mice. Transgenic Cdk8 overexpression resulted in progressive dilated cardiomyopathy, heart failure, and premature lethality. Prior to functional decline, left ventricular cardiomyocytes were dramatically elongated, with disorganized transverse tubules and dysfunctional calcium handling. RNA sequencing results showed that myofilament gene isoforms not typically expressed in adult cardiomyocytes were enriched, while oxidative phosphorylation and fatty acid biosynthesis genes were downregulated. Interestingly, candidate upstream transcription factor expression levels and MAPK signaling pathways thought to determine cardiomyocyte size remained relatively unaffected, suggesting that Cdk8 functions within a novel growth regulatory pathway. Our findings show that manipulating cardiac gene expression through increased Cdk8 levels is detrimental to the heart by establishing a transcriptional program that induces pathological remodeling and eccentric hypertrophy culminating in heart failure.
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Affiliation(s)
- Duane D Hall
- Department of Internal Medicine, Division of Cardiovascular Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Jessica M Ponce
- Department of Internal Medicine, Division of Cardiovascular Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Biyi Chen
- Department of Internal Medicine, Division of Cardiovascular Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Kathryn M Spitler
- Department of Internal Medicine, Division of Cardiovascular Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Adrianne Alexia
- Department of Internal Medicine, Division of Cardiovascular Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Gavin Y Oudit
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Long-Sheng Song
- Department of Internal Medicine, Division of Cardiovascular Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
| | - Chad E Grueter
- Department of Internal Medicine, Division of Cardiovascular Medicine, Francois M. Abboud Cardiovascular Research Center, Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa, USA
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16
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Abstract
Transcription by RNA polymerase (RNAP) II is regulated at multiple steps by phosphorylation, catalyzed mainly by members of the cyclin-dependent kinase (CDK) family. The CDKs involved in transcription have overlapping substrate specificities, but play largely non-redundant roles in coordinating gene expression. Novel functions and targets of CDKs have recently emerged at the end of the transcription cycle, when the primary transcript is cleaved, and in most cases polyadenylated, and transcription is terminated by the action of the "torpedo" exonuclease Xrn2, which is a CDK substrate. Collectively, various functions have been ascribed to CDKs or CDK-mediated phosphorylation: recruiting cleavage and polyadenylation factors, preventing premature termination within gene bodies while promoting efficient termination of full-length transcripts, and preventing extensive readthrough transcription into intergenic regions or neighboring genes. The assignment of precise functions to specific CDKs is still in progress, but recent advances suggest ways in which the CDK network and RNAP II machinery might cooperate to ensure timely exit from the transcription cycle.
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Affiliation(s)
- Robert P Fisher
- a Department of Oncological Sciences , Icahn School of Medicine at Mount Sinai , New York , NY , USA
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17
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Baranello L, Wojtowicz D, Cui K, Devaiah BN, Chung HJ, Chan-Salis KY, Guha R, Wilson K, Zhang X, Zhang H, Piotrowski J, Thomas CJ, Singer DS, Pugh BF, Pommier Y, Przytycka TM, Kouzine F, Lewis BA, Zhao K, Levens D. RNA Polymerase II Regulates Topoisomerase 1 Activity to Favor Efficient Transcription. Cell 2016; 165:357-71. [PMID: 27058666 DOI: 10.1016/j.cell.2016.02.036] [Citation(s) in RCA: 182] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 12/01/2015] [Accepted: 02/17/2016] [Indexed: 11/24/2022]
Abstract
We report a mechanism through which the transcription machinery directly controls topoisomerase 1 (TOP1) activity to adjust DNA topology throughout the transcription cycle. By comparing TOP1 occupancy using chromatin immunoprecipitation sequencing (ChIP-seq) versus TOP1 activity using topoisomerase 1 sequencing (TOP1-seq), a method reported here to map catalytically engaged TOP1, TOP1 bound at promoters was discovered to become fully active only after pause-release. This transition coupled the phosphorylation of the carboxyl-terminal-domain (CTD) of RNA polymerase II (RNAPII) with stimulation of TOP1 above its basal rate, enhancing its processivity. TOP1 stimulation is strongly dependent on the kinase activity of BRD4, a protein that phosphorylates Ser2-CTD and regulates RNAPII pause-release. Thus the coordinated action of BRD4 and TOP1 overcame the torsional stress opposing transcription as RNAPII commenced elongation but preserved negative supercoiling that assists promoter melting at start sites. This nexus between transcription and DNA topology promises to elicit new strategies to intercept pathological gene expression.
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Affiliation(s)
| | | | - Kairong Cui
- Systems Biology Center, NHLBI/NIH, Bethesda, MD 20892, USA
| | | | - Hye-Jung Chung
- Laboratory of Pathology, NCI/NIH, Bethesda, MD 20892, USA
| | - Ka Yim Chan-Salis
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Rajarshi Guha
- Division of Preclinical Innovation, NCATS/NIH, Rockville, MD 20850, USA
| | - Kelli Wilson
- Division of Preclinical Innovation, NCATS/NIH, Rockville, MD 20850, USA
| | - Xiaohu Zhang
- Division of Preclinical Innovation, NCATS/NIH, Rockville, MD 20850, USA
| | - Hongliang Zhang
- Development Therapeutics Branch and Laboratory of Molecular Pharmacology, NCI/NIH, Bethesda, MD 20892, USA
| | | | - Craig J Thomas
- Division of Preclinical Innovation, NCATS/NIH, Rockville, MD 20850, USA
| | - Dinah S Singer
- Experimental Immunology Branch, NCI/NIH, Bethesda, MD 20892, USA
| | - B Franklin Pugh
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Yves Pommier
- Development Therapeutics Branch and Laboratory of Molecular Pharmacology, NCI/NIH, Bethesda, MD 20892, USA
| | | | - Fedor Kouzine
- Laboratory of Pathology, NCI/NIH, Bethesda, MD 20892, USA
| | - Brian A Lewis
- Lymphoid Malignancies Branch, NCI/NIH, Bethesda, MD 20892, USA
| | - Keji Zhao
- Systems Biology Center, NHLBI/NIH, Bethesda, MD 20892, USA.
| | - David Levens
- Laboratory of Pathology, NCI/NIH, Bethesda, MD 20892, USA.
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18
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Ayaz P, Andres D, Kwiatkowski DA, Kolbe CC, Lienau P, Siemeister G, Lücking U, Stegmann CM. Conformational Adaption May Explain the Slow Dissociation Kinetics of Roniciclib (BAY 1000394), a Type I CDK Inhibitor with Kinetic Selectivity for CDK2 and CDK9. ACS Chem Biol 2016; 11:1710-9. [PMID: 27090615 DOI: 10.1021/acschembio.6b00074] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Roniciclib (BAY 1000394) is a type I pan-CDK (cyclin-dependent kinase) inhibitor which has revealed potent efficacy in xenograft cancer models. Here, we show that roniciclib displays prolonged residence times on CDK2 and CDK9, whereas residence times on other CDKs are transient, thus giving rise to a kinetic selectivity of roniciclib. Surprisingly, variation of the substituent at the 5-position of the pyrimidine scaffold results in changes of up to 3 orders of magnitude of the drug-target residence time. CDK2 X-ray cocrystal structures have revealed a DFG-loop adaption for the 5-(trifluoromethyl) substituent, while for hydrogen and bromo substituents the DFG loop remains in its characteristic type I inhibitor position. In tumor cells, the prolonged residence times of roniciclib on CDK2 and CDK9 are reflected in a sustained inhibitory effect on retinoblastoma protein (RB) phosphorylation, indicating that the target residence time on CDK2 may contribute to sustained target engagement and antitumor efficacy.
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Affiliation(s)
- Pelin Ayaz
- Bayer Pharma AG, Drug Discovery, Lead Discovery
Berlin, Berlin, Germany
| | - Dorothee Andres
- Bayer Pharma AG, Drug Discovery, Lead Discovery
Berlin, Berlin, Germany
| | | | | | - Philip Lienau
- Bayer Pharma AG, Drug Discovery, Research Pharmacokinetics, Berlin, Germany
| | | | - Ulrich Lücking
- Bayer Pharma AG, Drug Discovery, Medicinal Chemistry, Berlin, Germany
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19
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Sonawane YA, Taylor MA, Napoleon JV, Rana S, Contreras JI, Natarajan A. Cyclin Dependent Kinase 9 Inhibitors for Cancer Therapy. J Med Chem 2016; 59:8667-8684. [PMID: 27171036 PMCID: PMC5636177 DOI: 10.1021/acs.jmedchem.6b00150] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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Cyclin dependent kinase (CDK) inhibitors
have been the topic of intense research for nearly 2 decades due to
their widely varied and critical functions within the cell. Recently
CDK9 has emerged as a druggable target for the development of cancer
therapeutics. CDK9 plays a crucial role in transcription regulation;
specifically, CDK9 mediated transcriptional regulation of short-lived
antiapoptotic proteins is critical for the survival of transformed
cells. Focused chemical libraries based on a plethora of scaffolds
have resulted in mixed success with regard to the development of selective
CDK9 inhibitors. Here we review the regulation of CDK9, its cellular
functions, and common core structures used to target CDK9, along with
their selectivity profile and efficacy in vitro and in vivo.
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Affiliation(s)
- Yogesh A Sonawane
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Margaret A Taylor
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - John Victor Napoleon
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Sandeep Rana
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Jacob I Contreras
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
| | - Amarnath Natarajan
- Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center , Omaha, Nebraska 68198-6805, United States
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20
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Sansó M, Levin RS, Lipp JJ, Wang VYF, Greifenberg AK, Quezada EM, Ali A, Ghosh A, Larochelle S, Rana TM, Geyer M, Tong L, Shokat KM, Fisher RP. P-TEFb regulation of transcription termination factor Xrn2 revealed by a chemical genetic screen for Cdk9 substrates. Genes Dev 2016; 30:117-31. [PMID: 26728557 PMCID: PMC4701974 DOI: 10.1101/gad.269589.115] [Citation(s) in RCA: 95] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sansó et al. identified ∼100 putative substrates of human positive transcription elongation factor b (P-TEFb), which were enriched for proteins implicated in transcription and RNA catabolism. Among the RNA processing factors phosphorylated by Cdk9 was the 5′-to-3′ “torpedo” exoribonuclease Xrn2, required in transcription termination by Pol II. The transcription cycle of RNA polymerase II (Pol II) is regulated at discrete transition points by cyclin-dependent kinases (CDKs). Positive transcription elongation factor b (P-TEFb), a complex of Cdk9 and cyclin T1, promotes release of paused Pol II into elongation, but the precise mechanisms and targets of Cdk9 action remain largely unknown. Here, by a chemical genetic strategy, we identified ∼100 putative substrates of human P-TEFb, which were enriched for proteins implicated in transcription and RNA catabolism. Among the RNA processing factors phosphorylated by Cdk9 was the 5′-to-3′ “torpedo” exoribonuclease Xrn2, required in transcription termination by Pol II, which we validated as a bona fide P-TEFb substrate in vivo and in vitro. Phosphorylation by Cdk9 or phosphomimetic substitution of its target residue, Thr439, enhanced enzymatic activity of Xrn2 on synthetic substrates in vitro. Conversely, inhibition or depletion of Cdk9 or mutation of Xrn2-Thr439 to a nonphosphorylatable Ala residue caused phenotypes consistent with inefficient termination in human cells: impaired Xrn2 chromatin localization and increased readthrough transcription of endogenous genes. Therefore, in addition to its role in elongation, P-TEFb regulates termination by promoting chromatin recruitment and activation of a cotranscriptional RNA processing enzyme, Xrn2.
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Affiliation(s)
- Miriam Sansó
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Rebecca S Levin
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Jesse J Lipp
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Vivien Ya-Fan Wang
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Ann Katrin Greifenberg
- Department of Structural Immunology, Institute of Innate Immunity, University of Bonn, 53127 Bonn, Germany
| | - Elizabeth M Quezada
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Akbar Ali
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Animesh Ghosh
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Stéphane Larochelle
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Tariq M Rana
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA; Department of Pediatrics, University of California at San Diego School of Medicine, La Jolla, California 92093, USA
| | - Matthias Geyer
- Department of Pediatrics, University of California at San Diego School of Medicine, La Jolla, California 92093, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology, University of California at San Francisco, San Francisco, California 94143, USA; Howard Hughes Medical Institute, University of California at San Francisco, San Francisco, California 94143, USA
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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21
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Pinhero R, Yankulov K. Expression and Purification of Recombinant CDKs: CDK7, CDK8, and CDK9. Methods Mol Biol 2016; 1336:13-28. [PMID: 26231705 DOI: 10.1007/978-1-4939-2926-9_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cyclin-dependent kinases have established roles in the regulation of cell cycle, in gene expression and in cell differentiation. Many of these kinases have been considered as drug targets and numerous efforts have been made to develop specific and potent inhibitors against them. The first step in all of these attempts and in many other biochemical analyses is the production of highly purified and reliable kinase, most frequently in a recombinant form. In this chapter we describe our experience in the cloning, expression, and purification of CDKs using CDK7/CycH, CDK8/CycC, and CDK9/CycT1 as an example.
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Affiliation(s)
- Reena Pinhero
- Department of Molecular Biology and Genetics, University of Guelph, 50 Stone Road East, Guelph, ON, Canada, N1G 2W1
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22
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Storch K, Cordes N. The impact of CDK9 on radiosensitivity, DNA damage repair and cell cycling of HNSCC cancer cells. Int J Oncol 2015; 48:191-8. [PMID: 26573875 DOI: 10.3892/ijo.2015.3246] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/09/2015] [Indexed: 11/06/2022] Open
Abstract
Cyclin-dependent kinase 9 (CDK9), mainly involved in regulation of transcription, has recently been shown to impact on cell cycling and DNA repair. Despite the fact that CDK9 has been proposed as potential cancer target, it remains largely elusive whether CDK9 targeting alters tumor cell radiosensitivity. Five human head and neck squamous cell carcinoma (HNSCC) cell lines (SAS, FaDu, HSC4, Cal33, UTSCC5) as well as SAS cells stably transfected with CDK9-EGFP-N1 plasmid or empty vector controls were used. Upon either CDK9 small interfering RNA knockdown or treatment with a pan-CDK inhibitor (ZK304709), colony formation, DNA double strand breaks (DSBs), apoptosis, cell cycling, and expression and phosphorylation of major cell cycle and DNA damage repair proteins were examined. While CDK9 overexpression mediated radioprotection, CDK9 depletion clearly enhanced the radiosensitivity of HNSCC cells without an induction of apoptosis. While the cell cycle and cell cycle proteins were significantly modulated by CDK9 depletion, no further alterations in these parameters were observed after combined CDK9 knockdown with irradiation. ZK304709 showed concentration-dependent cytotoxicity but failed to radiosensitize HNSCC cells. Our findings suggest a potential role of CDK9 in the radiation response of HNSCC cells. Additional studies are warranted to clarify the usefulness to target CDK9 in the clinic.
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Affiliation(s)
- Katja Storch
- OncoRay - National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, D-01307 Dresden, Germany
| | - Nils Cordes
- OncoRay - National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, D-01307 Dresden, Germany
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23
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Marschalek R. MLL Leukemia and Future Treatment Strategies. Arch Pharm (Weinheim) 2015; 348:221-8. [DOI: 10.1002/ardp.201400449] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 12/05/2014] [Accepted: 01/16/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Rolf Marschalek
- Institute of Pharmaceutical Biology; Goethe-University; Frankfurt/Main Germany
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24
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Genome-wide targeting of the epigenetic regulatory protein CTCF to gene promoters by the transcription factor TFII-I. Proc Natl Acad Sci U S A 2015; 112:E677-86. [PMID: 25646466 DOI: 10.1073/pnas.1416674112] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
CCCTC-binding factor (CTCF) is a key regulator of nuclear chromatin structure and gene regulation. The impact of CTCF on transcriptional output is highly varied, ranging from repression to transcriptional pausing and transactivation. The multifunctional nature of CTCF may be directed solely through remodeling chromatin architecture. However, another hypothesis is that the multifunctional nature of CTCF is mediated, in part, through differential association with protein partners having unique functions. Consistent with this hypothesis, our mass spectrometry analyses of CTCF interacting partners reveal a previously undefined association with the transcription factor general transcription factor II-I (TFII-I). Biochemical fractionation of CTCF indicates that a distinct CTCF complex incorporating TFII-I is assembled on DNA. Unexpectedly, we found that the interaction between CTCF and TFII-I is essential for directing CTCF to the promoter proximal regulatory regions of target genes across the genome, particularly at genes involved in metabolism. At genes coregulated by CTCF and TFII-I, we find knockdown of TFII-I results in diminished CTCF binding, lack of cyclin-dependent kinase 8 (CDK8) recruitment, and an attenuation of RNA polymerase II phosphorylation at serine 5. Phenotypically, knockdown of TFII-I alters the cellular response to metabolic stress. Our data indicate that TFII-I directs CTCF binding to target genes, and in turn the two proteins cooperate to recruit CDK8 and enhance transcription initiation.
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25
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Puri D, Gala H, Mishra R, Dhawan J. High-wire act: the poised genome and cellular memory. FEBS J 2014; 282:1675-91. [PMID: 25440020 DOI: 10.1111/febs.13165] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 11/22/2014] [Accepted: 11/27/2014] [Indexed: 12/12/2022]
Abstract
Emerging evidence aided by genome-wide analysis of chromatin and transcriptional states has shed light on the mechanisms by which stem cells achieve cellular memory. The epigenetic and transcriptional plasticity governing stem cell behavior is highlighted by the identification of 'poised' genes, which permit cells to maintain readiness to undertake alternate developmental fates. This review focuses on two crucial mechanisms of gene poising: bivalent chromatin marks and RNA polymerase II stalling. We provide the context for these mechanisms by exploring the current consensus on the regulation of chromatin states, especially in quiescent adult stem cells, where poised genes are critical for recapitulating developmental choices, leading to regenerative function.
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Affiliation(s)
- Deepika Puri
- Council of Scientific and Industrial Research-Centre for Cellular and Molecular Biology, Hyderabad, India
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26
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Abstract
CDKs (cyclin-dependent kinases) ensure directionality and fidelity of the eukaryotic cell division cycle. In a similar fashion, the transcription cycle is governed by a conserved subfamily of CDKs that phosphorylate Pol II (RNA polymerase II) and other substrates. A genetic model organism, the fission yeast Schizosaccharomyces pombe, has yielded robust models of cell-cycle control, applicable to higher eukaryotes. From a similar approach combining classical and chemical genetics, fundamental principles of transcriptional regulation by CDKs are now emerging. In the present paper, we review the current knowledge of each transcriptional CDK with respect to its substrate specificity, function in transcription and effects on chromatin modifications, highlighting the important roles of CDKs in ensuring quantity and quality control over gene expression in eukaryotes.
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27
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Bowman EA, Kelly WG. RNA polymerase II transcription elongation and Pol II CTD Ser2 phosphorylation: A tail of two kinases. Nucleus 2014; 5:224-36. [PMID: 24879308 DOI: 10.4161/nucl.29347] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The transition between initiation and productive elongation during RNA Polymerase II (Pol II) transcription is a well-appreciated point of regulation across many eukaryotes. Elongating Pol II is modified by phosphorylation of serine 2 (Ser2) on its carboxy terminal domain (CTD) by two kinases, Bur1/Ctk1 in yeast and Cdk9/Cdk12 in metazoans. Here, we discuss the roles and regulation of these kinases and their relationship to Pol II elongation control, and focus on recent data from work in C. elegans that point out gaps in our current understand of transcription elongation.
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Affiliation(s)
- Elizabeth A Bowman
- National Institute of Environmental Health Sciences; Research Triangle Park, NC USA
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28
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Stress induces changes in the phosphorylation of Trypanosoma cruzi RNA polymerase II, affecting its association with chromatin and RNA processing. EUKARYOTIC CELL 2014; 13:855-65. [PMID: 24813189 DOI: 10.1128/ec.00066-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The phosphorylation of the carboxy-terminal heptapeptide repeats of the largest subunit of RNA polymerase II (Pol II) controls several transcription-related events in eukaryotes. Trypanosomatids lack these typical repeats and display an unusual transcription control. RNA Pol II associates with the transcription site of the spliced leader (SL) RNA, which is used in the trans-splicing of all mRNAs transcribed on long polycistronic units. We found that Trypanosoma cruzi RNA Pol II associated with chromatin is highly phosphorylated. When transcription is inhibited by actinomycin D, the enzyme runs off from SL genes, remaining hyperphosphorylated and associated with polycistronic transcription units. Upon heat shock, the enzyme is dephosphorylated and remains associated with the chromatin. Transcription is partially inhibited with the accumulation of housekeeping precursor mRNAs, except for heat shock genes. DNA damage caused dephosphorylation and transcription arrest, with RNA Pol II dissociating from chromatin although staying at the SL. In the presence of calyculin A, the hyperphosphorylated form detached from chromatin, including the SL loci. These results indicate that in trypanosomes, the unusual RNA Pol II is phosphorylated during the transcription of SL and polycistronic operons. Different types of stresses modify its phosphorylation state, affecting pre-RNA processing.
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29
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Yin T, Lallena MJ, Kreklau EL, Fales KR, Carballares S, Torrres R, Wishart GN, Ajamie RT, Cronier DM, Iversen PW, Meier TI, Foreman RT, Zeckner D, Sissons SE, Halstead BW, Lin AB, Donoho GP, Qian Y, Li S, Wu S, Aggarwal A, Ye XS, Starling JJ, Gaynor RB, de Dios A, Du J. A novel CDK9 inhibitor shows potent antitumor efficacy in preclinical hematologic tumor models. Mol Cancer Ther 2014; 13:1442-56. [PMID: 24688048 DOI: 10.1158/1535-7163.mct-13-0849] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
DNA-dependent RNA polymerase II (RNAP II) largest subunit RPB1 C-terminal domain (CTD) kinases, including CDK9, are serine/threonine kinases known to regulate transcriptional initiation and elongation by phosphorylating Ser 2, 5, and 7 residues on CTD. Given the reported dysregulation of these kinases in some cancers, we asked whether inhibiting CDK9 may induce stress response and preferentially kill tumor cells. Herein, we describe a potent CDK9 inhibitor, LY2857785, that significantly reduces RNAP II CTD phosphorylation and dramatically decreases MCL1 protein levels to result in apoptosis in a variety of leukemia and solid tumor cell lines. This molecule inhibits the growth of a broad panel of cancer cell lines, and is particularly efficacious in leukemia cells, including orthotopic leukemia preclinical models as well as in ex vivo acute myeloid leukemia and chronic lymphocytic leukemia patient tumor samples. Thus, inhibition of CDK9 may represent an interesting approach as a cancer therapeutic target, especially in hematologic malignancies.
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Affiliation(s)
- Tinggui Yin
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Maria J Lallena
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Emiko L Kreklau
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Kevin R Fales
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Santiago Carballares
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Raquel Torrres
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Graham N Wishart
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Rose T Ajamie
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Damien M Cronier
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Phillip W Iversen
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Timothy I Meier
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Robert T Foreman
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Douglas Zeckner
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Sean E Sissons
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Bart W Halstead
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Aimee B Lin
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Gregory P Donoho
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Yuewei Qian
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Shuyu Li
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Song Wu
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Amit Aggarwal
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Xiang S Ye
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - James J Starling
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Richard B Gaynor
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Alfonso de Dios
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
| | - Jian Du
- Authors' Affiliations: Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana; Eli Lilly and Company, Alcobendas, Madrid, Spain; and Eli Lilly and Company, Windlesham, United Kingdom
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30
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Kwon I, Kato M, Xiang S, Wu L, Theodoropoulos P, Mirzaei H, Han T, Xie S, Corden JL, McKnight SL. Phosphorylation-regulated binding of RNA polymerase II to fibrous polymers of low-complexity domains. Cell 2014; 155:1049-1060. [PMID: 24267890 DOI: 10.1016/j.cell.2013.10.033] [Citation(s) in RCA: 414] [Impact Index Per Article: 41.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/13/2013] [Accepted: 10/01/2013] [Indexed: 12/29/2022]
Abstract
The low-complexity (LC) domains of the products of the fused in sarcoma (FUS), Ewings sarcoma (EWS), and TAF15 genes are translocated onto a variety of different DNA-binding domains and thereby assist in driving the formation of cancerous cells. In the context of the translocated fusion proteins, these LC sequences function as transcriptional activation domains. Here, we show that polymeric fibers formed from these LC domains directly bind the C-terminal domain (CTD) of RNA polymerase II in a manner reversible by phosphorylation of the iterated, heptad repeats of the CTD. Mutational analysis indicates that the degree of binding between the CTD and the LC domain polymers correlates with the strength of transcriptional activation. These studies offer a simple means of conceptualizing how RNA polymerase II is recruited to active genes in its unphosphorylated state and released for elongation following phosphorylation of the CTD.
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Affiliation(s)
- Ilmin Kwon
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Masato Kato
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Siheng Xiang
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Leeju Wu
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Pano Theodoropoulos
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Hamid Mirzaei
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Tina Han
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Shanhai Xie
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
| | - Jeffry L Corden
- Department of Molecular Biology and Genetics The Johns Hopkins University School of Medicine Baltimore, MD 21205
| | - Steven L McKnight
- Department of Biochemistry University of Texas Southwestern Medical Center 5323 Harry Hines Boulevard Dallas, TX 75390-9152
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31
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Corden JL. RNA polymerase II C-terminal domain: Tethering transcription to transcript and template. Chem Rev 2013; 113:8423-55. [PMID: 24040939 PMCID: PMC3988834 DOI: 10.1021/cr400158h] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jeffry L Corden
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore Maryland 21205, United States
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32
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Zhao W, Liu Y, Timani KA, He JJ. Tip110 protein binds to unphosphorylated RNA polymerase II and promotes its phosphorylation and HIV-1 long terminal repeat transcription. J Biol Chem 2013; 289:190-202. [PMID: 24217245 DOI: 10.1074/jbc.m113.529784] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription plays an important role in both HIV-1 gene expression and replication and mandates complicated but coordinated interactions between the host and virus. Our previous studies have shown that an HIV-1 Tat-interacting protein of 110 kDa, Tip110, binds to and enhances Tat function in Tat-mediated HIV-1 gene transcription and replication (Liu, Y., Li, J., Kim, B. O., Pace, B. S., and He, J. J. (2002) HIV-1 Tat protein-mediated transactivation of the HIV-1 long terminal repeat promoter is potentiated by a novel nuclear Tat-interacting protein of 110 kDa, Tip110. J. Biol. Chem. 277, 23854-23863). However, the underlying molecular mechanisms by which this takes place were not understood. In this study, we demonstrated that Tip110 bound to unphosphorylated RNA polymerase II (RNAPII) in a direct and specific manner. In addition, we detected Tip110 at the HIV-1 long terminal repeat (LTR) promoter and found that Tip110 expression was associated with increased phosphorylation of serine 2 of the heptapeptide repeats within the RNAPII C-terminal domain and increased recruitment of positive transcription elongation factor b to the LTR promoter. Consistent with these findings, we showed that Tip110 interaction with Tat directly enhanced transcription elongation of the LTR promoter. Taken together, these findings have provided additional and mechanistic evidence to support Tip110 function in HIV-1 transcription.
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Affiliation(s)
- Weina Zhao
- From the Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana 46202 and
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33
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Wogonin induced G1 cell cycle arrest by regulating Wnt/β-catenin signaling pathway and inactivating CDK8 in human colorectal cancer carcinoma cells. Toxicology 2013; 312:36-47. [DOI: 10.1016/j.tox.2013.07.013] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Revised: 07/16/2013] [Accepted: 07/18/2013] [Indexed: 02/02/2023]
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Abstract
Elongation is becoming increasingly recognized as a critical step in eukaryotic transcriptional regulation. Although traditional genetic and biochemical studies have identified major players of transcriptional elongation, our understanding of the importance and roles of these factors is evolving rapidly through the recent advances in genome-wide and single-molecule technologies. Here, we focus on how elongation can modulate the transcriptional outcome through the rate-liming step of RNA polymerase II (Pol II) pausing near promoters and how the participating factors were identified. Among the factors we describe are the pausing factors--NELF (negative elongation factor) and DSIF (DRB sensitivity-inducing factor)--and P-TEFb (positive elongation factor b), which is the key player in pause release. We also describe the high-resolution view of Pol II pausing and propose nonexclusive models for how pausing is achieved. We then discuss Pol II elongation through the bodies of genes and the roles of FACT and SPT6, factors that allow Pol II to move through nucleosomes.
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Affiliation(s)
- Hojoong Kwak
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703; ,
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Affiliation(s)
- Dirk Eick
- Department of Molecular Epigenetics, Helmholtz Center Munich and Center for Integrated Protein Science Munich (CIPSM), Marchioninistrasse 25, 81377 Munich,
Germany
| | - Matthias Geyer
- Center of Advanced European Studies and Research, Group Physical Biochemistry,
Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
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Karn J, Stoltzfus CM. Transcriptional and posttranscriptional regulation of HIV-1 gene expression. Cold Spring Harb Perspect Med 2013; 2:a006916. [PMID: 22355797 DOI: 10.1101/cshperspect.a006916] [Citation(s) in RCA: 276] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Control of HIV-1 gene expression depends on two viral regulatory proteins, Tat and Rev. Tat stimulates transcription elongation by directing the cellular transcriptional elongation factor P-TEFb to nascent RNA polymerases. Rev is required for the transport from the nucleus to the cytoplasm of the unspliced and incompletely spliced mRNAs that encode the structural proteins of the virus. Molecular studies of both proteins have revealed how they interact with the cellular machinery to control transcription from the viral LTR and regulate the levels of spliced and unspliced mRNAs. The regulatory feedback mechanisms driven by HIV-1 Tat and Rev ensure that HIV-1 transcription proceeds through distinct phases. In cells that are not fully activated, limiting levels of Tat and Rev act as potent blocks to premature virus production.
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Affiliation(s)
- Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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Ribavirin-induced intracellular GTP depletion activates transcription elongation in coagulation factor VII gene expression. Biochem J 2013; 449:231-9. [PMID: 23050902 DOI: 10.1042/bj20121286] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Coagulation FVII (Factor VII) is a vitamin K-dependent glycoprotein synthesized in hepatocytes. It was reported previously that FVII gene (F7) expression was up-regulated by ribavirin treatment in hepatitis C virus-infected haemophilia patients; however, its precise mechanism is still unknown. In the present study, we investigated the molecular mechanism of ribavirin-induced up-regulation of F7 expression in HepG2 (human hepatoma cell line). We found that intracellular GTP depletion by ribavirin as well as other IMPDH (inosine-5'-monophosphate dehydrogenase) inhibitors, such as mycophenolic acid and 6-mercaptopurine, up-regulated F7 expression. FVII mRNA transcription was mainly enhanced by accelerated transcription elongation, which was mediated by the P-TEFb (positive-transcription elongation factor b) complex, rather than by promoter activation. Ribavirin unregulated ELL (eleven-nineteen lysine-rich leukaemia) 3 mRNA expression before F7 up-regulation. We observed that ribavirin enhanced ELL3 recruitment to F7, whereas knockdown of ELL3 diminished ribavirin-induced FVII mRNA up-regulation. Ribavirin also enhanced recruitment of CDK9 (cyclin-dependent kinase 9) and AFF4 to F7. These data suggest that ribavirin-induced intracellular GTP depletion recruits a super elongation complex containing P-TEFb, AFF4 and ELL3, to F7, and modulates FVII mRNA transcription elongation. Collectively, we have elucidated a basal mechanism for ribavirin-induced FVII mRNA up-regulation by acceleration of transcription elongation, which may be crucial in understanding its pleiotropic functions in vivo.
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Interaction of cyclin-dependent kinase 12/CrkRS with cyclin K1 is required for the phosphorylation of the C-terminal domain of RNA polymerase II. Mol Cell Biol 2012; 32:4691-704. [PMID: 22988298 DOI: 10.1128/mcb.06267-11] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CrkRS (Cdc2-related kinase, Arg/Ser), or cyclin-dependent kinase 12 (CKD12), is a serine/threonine kinase believed to coordinate transcription and RNA splicing. While CDK12/CrkRS complexes were known to phosphorylate the C-terminal domain (CTD) of RNA polymerase II (RNA Pol II), the cyclin regulating this activity was not known. Using immunoprecipitation and mass spectrometry, we identified a 65-kDa isoform of cyclin K (cyclin K1) in endogenous CDK12/CrkRS protein complexes. We show that cyclin K1 complexes isolated from mammalian cells contain CDK12/CrkRS but do not contain CDK9, a presumed partner of cyclin K. Analysis of extensive RNA-Seq data shows that the 65-kDa cyclin K1 isoform is the predominantly expressed form across numerous tissue types. We also demonstrate that CDK12/CrkRS is dependent on cyclin K1 for its kinase activity and that small interfering RNA (siRNA) knockdown of CDK12/CrkRS or cyclin K1 has similar effects on the expression of a luciferase reporter gene. Our data suggest that cyclin K1 is the primary cyclin partner for CDK12/CrkRS and that cyclin K1 is required to activate CDK12/CrkRS to phosphorylate the CTD of RNA Pol II. These properties are consistent with a role of CDK12/CrkRS in regulating gene expression through phosphorylation of RNA Pol II.
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Siemeister G, Lücking U, Wengner AM, Lienau P, Steinke W, Schatz C, Mumberg D, Ziegelbauer K. BAY 1000394, a novel cyclin-dependent kinase inhibitor, with potent antitumor activity in mono- and in combination treatment upon oral application. Mol Cancer Ther 2012; 11:2265-73. [PMID: 22821149 DOI: 10.1158/1535-7163.mct-12-0286] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Deregulated activity of cyclin-dependent kinases (CDK) results in loss of cell-cycle checkpoint function and increased expression of antiapoptotic proteins, which has been directly linked to the molecular pathology of cancer. BAY 1000394 inhibits the activity of cell-cycle CDKs CDK1, CDK2, CDK3, CDK4, and of transcriptional CDKs CDK7 and CDK9 with IC(50) values in the range between 5 and 25 nmol/L. Cell proliferation was inhibited at low nanomolar concentration in a broad spectrum of human cancer cell lines. In cell-based assays, the inhibition of phosphorylation of the CDK substrates retinoblastoma protein, nucleophosmin, and RNA polymerase II was shown. Cell-cycle profiles were consistent with inhibition of CDK 1, 2, and 4 as shown in cell-cycle block and release experiments. The physicochemical and pharmacokinetic properties of BAY 1000394 facilitate rapid absorption and moderate oral bioavailability. The compound potently inhibits growth of various human tumor xenografts on athymic mice including models of chemotherapy resistance upon oral dosing. Furthermore, BAY 1000394 shows more than additive efficacy when combined with cisplatin and etoposide. These results suggest that BAY 1000394 is a potent pan-CDK inhibitor and a novel oral cytotoxic agent currently in phase I clinical trials.
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Affiliation(s)
- Gerhard Siemeister
- Bayer Pharma AG, Global Drug Discovery/TRG-ONC/GT, Mullerstrasse 178, D-13342 Berlin, Germany.
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Phosphatase PPM1A negatively regulates P-TEFb function in resting CD4(+) T cells and inhibits HIV-1 gene expression. Retrovirology 2012; 9:52. [PMID: 22727189 PMCID: PMC3406988 DOI: 10.1186/1742-4690-9-52] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Accepted: 06/22/2012] [Indexed: 11/16/2022] Open
Abstract
Background Processive elongation of the integrated HIV-1 provirus is dependent on recruitment of P-TEFb by the viral Tat protein to the viral TAR RNA element. P-TEFb kinase activity requires phosphorylation of Thr186 in the T-loop of the CDK9 subunit. In resting CD4+T cells, low levels of T-loop phosphorylated CDK9 are found, which increase significantly upon activation. This suggests that the phosphorylation status of the T-loop is actively regulated through the concerted actions of cellular proteins such as Ser/Thr phosphatases. We investigated the role of phosphatase PPM1A in regulating CDK9 T-loop phosphorylation and its effect on HIV-1 proviral transcription. Results We found that overexpression of PPM1A inhibits HIV-1 gene expression during viral infection and this required PPM1A catalytic function. Using an artificial CDK tethering system, we further found that PPM1A inhibits CDK9, but not CDK8 mediated activation of the HIV-1 LTR. SiRNA depletion of PPM1A in resting CD4+T cells increased the level of CDK9 T-loop phosphorylation and enhanced HIV-1 gene expression. We also observed that PPM1A protein levels are relatively high in resting CD4+T cells and are not up-regulated upon T cell activation. Conclusions Our results establish a functional link between HIV-1 replication and modulation of CDK9 T-loop phosphorylation by PPM1A. PPM1A represses HIV-1 gene expression by inhibiting CDK9 T-loop phosphorylation, thus reducing the amount of active P-TEFb available for recruitment to the viral LTR. We also infer that PPM1A enzymatic activity in resting and activated CD4+ T cells are likely regulated by as yet undefined factors.
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Zhao X, Feng D, Wang Q, Abdulla A, Xie XJ, Zhou J, Sun Y, Yang ES, Liu LP, Vaitheesvaran B, Bridges L, Kurland IJ, Strich R, Ni JQ, Wang C, Ericsson J, Pessin JE, Ji JY, Yang F. Regulation of lipogenesis by cyclin-dependent kinase 8-mediated control of SREBP-1. J Clin Invest 2012; 122:2417-27. [PMID: 22684109 DOI: 10.1172/jci61462] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Accepted: 05/02/2012] [Indexed: 01/09/2023] Open
Abstract
Altered lipid metabolism underlies several major human diseases, including obesity and type 2 diabetes. However, lipid metabolism pathophysiology remains poorly understood at the molecular level. Insulin is the primary stimulator of hepatic lipogenesis through activation of the SREBP-1c transcription factor. Here we identified cyclin-dependent kinase 8 (CDK8) and its regulatory partner cyclin C (CycC) as negative regulators of the lipogenic pathway in Drosophila, mammalian hepatocytes, and mouse liver. The inhibitory effect of CDK8 and CycC on de novo lipogenesis was mediated through CDK8 phosphorylation of nuclear SREBP-1c at a conserved threonine residue. Phosphorylation by CDK8 enhanced SREBP-1c ubiquitination and protein degradation. Importantly, consistent with the physiologic regulation of lipid biosynthesis, CDK8 and CycC proteins were rapidly downregulated by feeding and insulin, resulting in decreased SREBP-1c phosphorylation. Moreover, overexpression of CycC efficiently suppressed insulin and feeding-induced lipogenic gene expression. Taken together, these results demonstrate that CDK8 and CycC function as evolutionarily conserved components of the insulin signaling pathway in regulating lipid homeostasis.
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Affiliation(s)
- Xiaoping Zhao
- Department of Medicine, Division of Endocrinology, Diabetes Research and Training Center, Albert Einstein College of Medicine, New York, NY, USA
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42
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Fleetwood MR, Ho Y, Cooke NE, Liebhaber SA. DNase I hypersensitive site II of the human growth hormone locus control region mediates an essential and distinct long-range enhancer function. J Biol Chem 2012; 287:25454-65. [PMID: 22669946 DOI: 10.1074/jbc.m112.365825] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Locus control regions (LCRs) comprise sets of DNA elements capable of establishing autonomous chromatin domains that support robust and physiologically appropriate expression of target genes, often working over extensive distances. Human growth hormone (hGH-N) expression in the pituitary is under the regulation of a well characterized LCR containing four DNase I hypersensitive sites (HSs). The two pituitary-specific HS, HSI and HSII, are located 14.5 and 15.5 kb 5' to the hGH-N promoter. HSI is essential for activation of hGH-N during pituitary development and for sustaining robust activity in the adult. To determine whether the closely linked HSII has a role in hGH-N expression, it was deleted from a previously validated hGH/P1 transgene. Analysis of three independent hGH/P1(ΔHSII) transgenic mouse lines revealed that this deletion had no adverse effect on the formation of HSI, yet resulted in a substantial loss (70%) in hGH-N mRNA expression. This loss of expression was accompanied by a corresponding reduction in recruitment of the pituitary-specific transcription factor Pit-1 to the hGH-N promoter and a selective decrease in promoter occupancy of the elongation-linked isoform of RNA polymerase II. Sufficiency of HSI and HSII in LCR activity was explored by establishing two additional sets of mouse transgenic lines in which DNA segments containing these HS were positioned within the λ phage genome. In this "neutral" DNA context, HSII was required for the recruitment of HAT activity. These data establish HSII as a nonredundant component of the hGH LCR essential for establishment of robust levels of hGH-N gene expression.
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Affiliation(s)
- Margaret R Fleetwood
- Department of Genetics and Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Galbraith MD, Donner AJ, Espinosa JM. CDK8: a positive regulator of transcription. Transcription 2012; 1:4-12. [PMID: 21327159 DOI: 10.4161/trns.1.1.12373] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 05/12/2010] [Accepted: 05/13/2010] [Indexed: 01/09/2023] Open
Abstract
CDK8 belongs to a group of cyclin-dependent kinases involved in transcriptional regulation from yeast to mammals. CDK8 associates with the Mediator complex, but functions outside of Mediator are also likely. Historically, CDK8 has been described mostly as a transcriptional repressor, but a growing body of research provides unequivocal evidence for various roles of CDK8 in gene activation. Several transcriptional programs of biomedical importance employ CDK8 as a co-activator, including the p53 network, the Wnt/β-catenin pathway, the serum response network, and those governed by SMADs and the thyroid hormone receptor, thus highlighting the importance of further investigation into this enigmatic transcriptional regulator.
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Abstract
Regulation of the elongation phase of transcription by RNA polymerase II (Pol II) is utilized extensively to generate the pattern of mRNAs needed to specify cell types and to respond to environmental changes. After Pol II initiates, negative elongation factors cause it to pause in a promoter proximal position. These polymerases are poised to respond to the positive transcription elongation factor P-TEFb, and then enter productive elongation only under the appropriate set of signals to generate full-length properly processed mRNAs. Recent global analyses of Pol II and elongation factors, mechanisms that regulate P-TEFb involving the 7SK small nuclear ribonucleoprotein (snRNP), factors that control both the negative and positive elongation properties of Pol II, and the mRNA processing events that are coupled with elongation are discussed.
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Affiliation(s)
- Qiang Zhou
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.
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45
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Zhao Y, Ding X, Ye X, Dai ZM, Yang JS, Yang WJ. Involvement of cyclin K posttranscriptional regulation in the formation of Artemia diapause cysts. PLoS One 2012; 7:e32129. [PMID: 22363807 PMCID: PMC3283732 DOI: 10.1371/journal.pone.0032129] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 01/19/2012] [Indexed: 11/18/2022] Open
Abstract
Background Artemia eggs tend to develop ovoviviparously to yield nauplius larvae in good rearing conditions; while under adverse situations, they tend to develop oviparously and encysted diapause embryos are formed instead. However, the intrinsic mechanisms regulating this process are not well understood. Principal Finding This study has characterized the function of cyclin K, a regulatory subunit of the positive transcription elongation factor b (P-TEFb) in the two different developmental pathways of Artemia. In the diapause-destined embryo, Western blots showed that the cyclin K protein was down-regulated as the embryo entered dormancy and reverted to relatively high levels of expression once development resumed, consistent with the fluctuations in phosphorylation of position 2 serines (Ser2) in the C-terminal domain (CTD) of the largest subunit (Rpb1) of RNA polymerase II (RNAP II). Interestingly, the cyclin K transcript levels remained constant during this process. In vitro translation data indicated that the template activity of cyclin K mRNA stored in the postdiapause cyst was repressed. In addition, in vivo knockdown of cyclin K in developing embryos by RNA interference eliminated phosphorylation of the CTD Ser2 of RNAP II and induced apoptosis by inhibiting the extracellular signal-regulated kinase (ERK) survival signaling pathway. Conclusions/Significance Taken together, these findings reveal a role for cyclin K in regulating RNAP II activity during diapause embryo development, which involves the post-transcriptional regulation of cyclin K. In addition, a further role was identified for cyclin K in regulating the control of cell survival during embryogenesis through ERK signaling pathways.
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Affiliation(s)
- Yang Zhao
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Xia Ding
- College of Life Sciences, Nanchang University, Nanchang, Jiangxi, People's Republic of China
| | - Xiang Ye
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Zhong-Min Dai
- Institute of Developmental and Regenerative Biology, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang, People's Republic of China
| | - Jin-Shu Yang
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
| | - Wei-Jun Yang
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education and College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China
- * E-mail:
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46
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Mbonye U, Karn J. Control of HIV latency by epigenetic and non-epigenetic mechanisms. Curr HIV Res 2011; 9:554-67. [PMID: 22211660 PMCID: PMC3319922 DOI: 10.2174/157016211798998736] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 10/10/2011] [Accepted: 10/21/2011] [Indexed: 12/17/2022]
Abstract
Intensive antiretroviral therapy successfully suppresses viral replication but is unable to eradicate the virus. HIV persists in a small number of resting memory T cells where HIV has been transcriptionally silenced. This review will focus on recent insights into the HIV transcriptional control mechanisms that provide the biochemical basis for understanding latency. There are no specific repressors of HIV transcription encoded by the virus, instead latency arises when the regulatory feedback mechanism driven by HIV Tat expression is disrupted. Small changes in transcriptional initiation, induced by epigenetic silencing, lead to profound restrictions in Tat levels and force the entry of proviruses into latency. In resting memory T cells, which carry the bulk of the latent viral pool, additional restrictions, especially the limiting cellular levels of the essential Tat cofactor P-TEFb and the transcription initiation factors NF-κB and NFAT ensure that the provirus remains silenced unless the host cell is activated. The detailed understanding of HIV transcription is providing a framework for devising new therapeutic strategies designed to purge the latent viral pool. Importantly, the recognition that there are multiple restrictions imposed on latent proviruses suggest that proviral reactivation will not be achieved when only a single reactivation step is targeted and that any optimal activation strategy will require both removal of epigenetic blocks and the activation of P-TEFb.
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Affiliation(s)
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106, USA
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Liu X, Shi S, Lam F, Pepper C, Fischer PM, Wang S. CDKI-71, a novel CDK9 inhibitor, is preferentially cytotoxic to cancer cells compared to flavopiridol. Int J Cancer 2011; 130:1216-26. [PMID: 21484792 DOI: 10.1002/ijc.26127] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 03/25/2011] [Indexed: 11/09/2022]
Abstract
Cancer cells appear to depend heavily on antiapoptotic proteins for survival and so targeted inhibition of these proteins has therapeutic potential. One innovative strategy is to inhibit the cyclin-dependent kinases (CDKs) responsible for the regulation of RNA polymerase II (RNAPII). In our study, we investigated the detailed cellular mechanism of a novel small-molecule CDK inhibitor (CDKI-71) in cancer cell lines, primary leukemia cells, normal B - & T- cells, and embryonic lung fibroblasts and compared the cellular and molecular responses to the clinical CDK inhibitor, flavopiridol. Like flavopiridol, CDKI-71 displayed potent cytotoxicity and caspase-dependent apoptosis induction that were closely associated with the inhibition of RNAPII phosphorylation at serine-2. This was caused by effective targeting of cyclinT-CDK9 and resulted in the downstream inhibition of Mcl-1. No correlation between apoptosis and inhibition of cell-cycle CDKs 1 and 2 was observed. CDKI-71 showed a 10-fold increase in potency in tumor cell lines when compared to MRC-5 human fibroblast cells. Significantly, CDKI-71 also demonstrated potent anti-chronic lymphocytic leukemia activity with minimal toxicity in normal B- and T-cells. In contrast, flavopiridol showed little selectivity between cancer and normal cells. Here, we provide the first cell-based evidence that flavopiridol induces DNA double-strand breaks: a fact which may explain why flavopiridol has such a narrow therapeutic window in preclinical and clinical settings. Taken together, our data provide a rationale for the development of selective CDK inhibitors as therapeutic agents and CDKI-71 represents a promising lead in this context.
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Affiliation(s)
- Xiangrui Liu
- School of Pharmacy and Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham, United Kingdom
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48
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Wang S, Griffiths G, Midgley CA, Barnett AL, Cooper M, Grabarek J, Ingram L, Jackson W, Kontopidis G, McClue SJ, McInnes C, McLachlan J, Meades C, Mezna M, Stuart I, Thomas MP, Zheleva DI, Lane DP, Jackson RC, Glover DM, Blake DG, Fischer PM. Discovery and characterization of 2-anilino-4- (thiazol-5-yl)pyrimidine transcriptional CDK inhibitors as anticancer agents. ACTA ACUST UNITED AC 2011; 17:1111-21. [PMID: 21035734 DOI: 10.1016/j.chembiol.2010.07.016] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2010] [Revised: 07/15/2010] [Accepted: 07/20/2010] [Indexed: 12/11/2022]
Abstract
The main difficulty in the development of ATP antagonist kinase inhibitors is target specificity, since the ATP-binding motif is present in many proteins. We introduce a strategy that has allowed us to identify compounds from a kinase inhibitor library that block the cyclin-dependent kinases responsible for regulating transcription, i.e., CDK7 and especially CDK9. The screening cascade employs cellular phenotypic assays based on mitotic index and nuclear p53 protein accumulation. This permitted us to classify compounds into transcriptional, cell cycle, and mitotic inhibitor groups. We describe the characterization of the transcriptional inhibitor class in terms of kinase inhibition profile, cellular mode of action, and selectivity for transformed cells. A structural selectivity rationale was used to optimize potency and biopharmaceutical properties and led to the development of a transcriptional inhibitor, 3,4-dimethyl-5-[2-(4-piperazin-1-yl-phenylamino)-pyrimidin-4-yl]-3H-thiazol-2-one, with anticancer activity in animal models.
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49
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Brewster CD, Birkenheuer CH, Vogt MB, Quackenbush SL, Rovnak J. The retroviral cyclin of walleye dermal sarcoma virus binds cyclin-dependent kinases 3 and 8. Virology 2010; 409:299-307. [PMID: 21067790 DOI: 10.1016/j.virol.2010.10.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 09/13/2010] [Accepted: 10/14/2010] [Indexed: 12/20/2022]
Abstract
Walleye dermal sarcoma virus encodes a retroviral cyclin (rv-cyclin) with a cyclin box fold and transcription activation domain (AD). Co-immune precipitation (co-IP) identified an association of rv-cyclin with cyclin-dependent kinase 8 (cdk8). Cdk8 is dependent upon cyclin C and regulates transcription with the Mediator complex, a co-activator of transcription. Mutation of cyclin residues, required for cdk binding, disrupts rv-cyclin-cdk8 co-IP. Mutation or removal of the AD has no effect on cdk8 interaction. Direct rv-cyclin-cdk8 binding is demonstrated by pulldown of active cdk8 and by GST-rv-cyclin binding to recombinant cdk8. Cdk3 is also activated by cyclin C and phosphorylates retinoblastoma protein to initiate entry into the cell division cycle. Co-IP and pulldowns demonstrate direct rv-cyclin binding to cdk3 as well. The rv-cyclin functions as a structural ortholog of cyclin C in spite of its limited amino acid sequence identity with C cyclins or with any known cyclins.
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Affiliation(s)
- Connie D Brewster
- Department of Microbiology, Immunology, and Pathology, 1619 Campus Delivery, Colorado State University, Fort Collins, CO 80523, USA.
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50
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Sub1 globally regulates RNA polymerase II C-terminal domain phosphorylation. Mol Cell Biol 2010; 30:5180-93. [PMID: 20823273 DOI: 10.1128/mcb.00819-10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The transcriptional coactivator Sub1 has been implicated in several aspects of mRNA metabolism in yeast, such as activation of transcription, termination, and 3'-end formation. Here, we present evidence that Sub1 plays a significant role in controlling phosphorylation of the RNA polymerase II large subunit C-terminal domain (CTD). We show that SUB1 genetically interacts with the genes encoding all four known CTD kinases, SRB10, KIN28, BUR1, and CTK1, suggesting that Sub1 acts to influence CTD phosphorylation at more than one step of the transcription cycle. To address this directly, we first used in vitro kinase assays, and we show that, on the one hand, SUB1 deletion increased CTD phosphorylation by Kin28, Bur1, and Ctk1 but, on the other, it decreased CTD phosphorylation by Srb10. Second, chromatin immunoprecipitation assays revealed that SUB1 deletion decreased Srb10 chromatin association on the inducible GAL1 gene but increased Kin28 and Ctk1 chromatin association on actively transcribed genes. Taken together, our data point to multiple roles for Sub1 in the regulation of CTD phosphorylation throughout the transcription cycle.
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