1
|
Velychko T, Mohammad E, Ferrer-Vicens I, Parfentev I, Werner M, Studniarek C, Schwalb B, Urlaub H, Murphy S, Cramer P, Lidschreiber M. CDK7 kinase activity promotes RNA polymerase II promoter escape by facilitating initiation factor release. Mol Cell 2024; 84:2287-2303.e10. [PMID: 38821049 DOI: 10.1016/j.molcel.2024.05.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 02/01/2024] [Accepted: 05/08/2024] [Indexed: 06/02/2024]
Abstract
Cyclin-dependent kinase 7 (CDK7), part of the general transcription factor TFIIH, promotes gene transcription by phosphorylating the C-terminal domain of RNA polymerase II (RNA Pol II). Here, we combine rapid CDK7 kinase inhibition with multi-omics analysis to unravel the direct functions of CDK7 in human cells. CDK7 inhibition causes RNA Pol II retention at promoters, leading to decreased RNA Pol II initiation and immediate global downregulation of transcript synthesis. Elongation, termination, and recruitment of co-transcriptional factors are not directly affected. Although RNA Pol II, initiation factors, and Mediator accumulate at promoters, RNA Pol II complexes can also proceed into gene bodies without promoter-proximal pausing while retaining initiation factors and Mediator. Further downstream, RNA Pol II phosphorylation increases and initiation factors and Mediator are released, allowing recruitment of elongation factors and an increase in RNA Pol II elongation velocity. Collectively, CDK7 kinase activity promotes the release of initiation factors and Mediator from RNA Pol II, facilitating RNA Pol II escape from the promoter.
Collapse
Affiliation(s)
- Taras Velychko
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
| | - Eusra Mohammad
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
| | - Ivan Ferrer-Vicens
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Iwan Parfentev
- Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
| | - Marcel Werner
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
| | - Cecilia Studniarek
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Björn Schwalb
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany; Institute of Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
| | - Michael Lidschreiber
- Department of Molecular Biology, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077 Göttingen, Germany.
| |
Collapse
|
2
|
Garralda E, Schram AM, Bedard PL, Schwartz GK, Yuen E, McNeely SC, Ribeiro S, Cunningham J, Wang Y, Urunuela A, Xu X, LoRusso P. A Phase I Dose-Escalation Study of LY3405105, a Covalent Inhibitor of Cyclin-Dependent Kinase 7, Administered to Patients With Advanced Solid Tumors. Oncologist 2024; 29:e131-e140. [PMID: 37531083 PMCID: PMC10769797 DOI: 10.1093/oncolo/oyad215] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Accepted: 07/16/2023] [Indexed: 08/03/2023] Open
Abstract
BACKGROUND This study aimed to evaluate the safety, pharmacokinetics (PKs), and preliminary activity of LY3405105, a covalent inhibitor of cyclin-dependent kinase 7 (CDK7), in patients with advanced solid tumors. MATERIALS AND METHODS LY3405105 monotherapy was given once daily (QD; part A1) or thrice weekly (TIW; part A2) starting at 1 and 2 mg orally, respectively, and escalated per a Bayesian design in adult patients. The primary endpoint was safety, and secondary endpoints included PKs and antitumor activity. RESULTS Fifty-four patients were enrolled: 43 in part A1 and 11 in part A2. Seven patients had dose-limiting toxicities, all in part A1 (45 mg: n = 3; 35 mg: n = 3; 25 mg: n = 1). Thirty-five patients (64.8%) reported at least one treatment-related adverse event (TRAE). TRAEs (≥10%) were diarrhea, nausea, fatigue, vomiting, abdominal pain, anemia, asthenia, and decreased platelet count. QD dosing showed sustained exposure with less peak-trough fluctuation compared to TIW dosing. Median time to maximum concentration was 1-2 hours and half-life was 15-19 hours. CDK7-target occupancy in skin and peripheral blood on day 15 was dose-dependent and reached near maximal occupancy of 75% at ≥15 mg QD. The maximum tolerated dose (MTD) was 20 mg QD. Twelve patients in part A1 (27.9%) and 5 patients in part A2 (45.5%) had a best overall response of stable disease. No complete response or partial response was observed. CONCLUSION The MTD of LY3405105 monotherapy was 20 mg QD. The most common toxicities were gastrointestinal adverse events, myelosuppression, fatigue, and asthenia. Limited clinical activity was observed in this phase I trial, and there are no plans for further development. CLINICALTRIALS.GOV IDENTIFIER NCT03770494.
Collapse
Affiliation(s)
- Elena Garralda
- Department of Medical Oncology, Vall d'Hebron University Hospital, Vall d'Hebron Institute of Oncology (VHIO), Barcelona, Spain
| | - Alison M Schram
- Department of Medicine, Memorial Sloan Kettering Cancer Center, Weill Cornell Medical College, New York, NY, USA
| | - Philippe L Bedard
- Division of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University Health Network, Toronto, Ontario, Canada
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Gary K Schwartz
- Columbia University Vagelos School of Medicine, Herbert Irving Comprehensive Cancer Center, New York, NY, USA
| | - Eunice Yuen
- Eli Lilly and Company, Indianapolis, IN, USA
| | | | | | | | - Yi Wang
- Eli Lilly and Company, Indianapolis, IN, USA
| | | | - Xiaojian Xu
- Eli Lilly and Company, Indianapolis, IN, USA
| | | |
Collapse
|
3
|
Kempen RP, Dabas P, Ansari AZ. The Phantom Mark: Enigmatic roles of phospho-Threonine 4 modification of the C-terminal domain of RNA polymerase II. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1771. [PMID: 36606410 PMCID: PMC10323045 DOI: 10.1002/wrna.1771] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 11/04/2022] [Accepted: 12/07/2022] [Indexed: 01/07/2023]
Abstract
The largest subunit of RNA polymerase II (Pol II) has an unusual carboxyl-terminal domain (CTD). This domain is composed of a tandemly repeating heptapeptide, Y1 S2 P3 T4 S5 P6 S7 , that has multiple roles in regulating Pol II function and processing newly synthesized RNA. Transient phosphorylation of Ser2 and Ser5 of the YS2 PTS5 PS repeat have well-defined roles in recruiting different protein complexes and coordinating sequential steps in gene transcription. As such, these phospho-marks encipher a molecular recognition code, colloquially termed the CTD code. In contrast, the contribution of phospho-Threonine 4 (pThr4/pT4) to the CTD code remains opaque and contentious. Fuelling the debate on the relevance of this mark to gene expression are the findings that replacing Thr4 with a valine or alanine has varied impact on cellular function in different species and independent proteomic analyses disagree on the relative abundance of pThr4 marks. Yet, substitution with negatively charged residues is lethal and even benign mutations selectively disrupt synthesis and 3' processing of distinct sets of coding and non-coding transcripts. Suggestive of non-canonical roles, pThr4 marked Pol II regulates distinct gene classes in a species- and signal-responsive manner. Hinting at undiscovered roles of this elusive mark, multiple signal-responsive kinases phosphorylate Thr4 at target genes. Here, we focus on this under-explored residue and postulate that the pThr4 mark is superimposed on the canonical CTD code to selectively regulate expression of targeted genes without perturbing genome-wide transcriptional processes. This article is categorized under: RNA Processing > 3' End Processing RNA Processing > Processing of Small RNAs RNA Processing > Splicing Regulation/Alternative Splicing.
Collapse
Affiliation(s)
- Ryan P Kempen
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Preeti Dabas
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| | - Aseem Z Ansari
- Department of Chemical Biology & Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
| |
Collapse
|
4
|
Constantin TA, Varela-Carver A, Greenland KK, de Almeida GS, Olden E, Penfold L, Ang S, Ormrod A, Leach DA, Lai CF, Ainscow EK, Bahl AK, Carling D, Fuchter MJ, Ali S, Bevan CL. The CDK7 inhibitor CT7001 (Samuraciclib) targets proliferation pathways to inhibit advanced prostate cancer. Br J Cancer 2023; 128:2326-2337. [PMID: 37076563 PMCID: PMC10241923 DOI: 10.1038/s41416-023-02252-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 03/15/2023] [Accepted: 03/21/2023] [Indexed: 04/21/2023] Open
Abstract
BACKGROUND Current strategies to inhibit androgen receptor (AR) are circumvented in castration-resistant prostate cancer (CRPC). Cyclin-dependent kinase 7 (CDK7) promotes AR signalling, in addition to established roles in cell cycle and global transcription, providing a rationale for its therapeutic targeting in CRPC. METHODS The antitumour activity of CT7001, an orally bioavailable CDK7 inhibitor, was investigated across CRPC models in vitro and in xenograft models in vivo. Cell-based assays and transcriptomic analyses of treated xenografts were employed to investigate the mechanisms driving CT7001 activity, alone and in combination with the antiandrogen enzalutamide. RESULTS CT7001 selectively engages with CDK7 in prostate cancer cells, causing inhibition of proliferation and cell cycle arrest. Activation of p53, induction of apoptosis, and suppression of transcription mediated by full-length and constitutively active AR splice variants contribute to antitumour efficacy in vitro. Oral administration of CT7001 represses growth of CRPC xenografts and significantly augments growth inhibition achieved by enzalutamide. Transcriptome analyses of treated xenografts indicate cell cycle and AR inhibition as the mode of action of CT7001 in vivo. CONCLUSIONS This study supports CDK7 inhibition as a strategy to target deregulated cell proliferation and demonstrates CT7001 is a promising CRPC therapeutic, alone or in combination with AR-targeting compounds.
Collapse
Affiliation(s)
- Theodora A Constantin
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Anabel Varela-Carver
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Kyle K Greenland
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Gilberto Serrano de Almeida
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Ellen Olden
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Lucy Penfold
- MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK
| | - Simon Ang
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Alice Ormrod
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Damien A Leach
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Chun-Fui Lai
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Edward K Ainscow
- Carrick Therapeutics, Nova UCD, Bellfield Innovation Park, Dublin, 4, Ireland
| | - Ash K Bahl
- Carrick Therapeutics, Nova UCD, Bellfield Innovation Park, Dublin, 4, Ireland
| | - David Carling
- MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital, London, UK
| | - Matthew J Fuchter
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, White City Campus, London, UK
| | - Simak Ali
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Charlotte L Bevan
- Imperial Centre for Translational and Experimental Medicine, Department of Surgery and Cancer, Imperial College London, Hammersmith Hospital Campus, London, UK.
| |
Collapse
|
5
|
Ford K, Munson BP, Fong SH, Panwala R, Chu WK, Rainaldi J, Plongthongkum N, Arunachalam V, Kostrowicki J, Meluzzi D, Kreisberg JF, Jensen-Pergakes K, VanArsdale T, Paul T, Tamayo P, Zhang K, Bienkowska J, Mali P, Ideker T. Multimodal perturbation analyses of cyclin-dependent kinases reveal a network of synthetic lethalities associated with cell-cycle regulation and transcriptional regulation. Sci Rep 2023; 13:7678. [PMID: 37169829 PMCID: PMC10175263 DOI: 10.1038/s41598-023-33329-2] [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: 11/15/2022] [Accepted: 04/11/2023] [Indexed: 05/13/2023] Open
Abstract
Cell-cycle control is accomplished by cyclin-dependent kinases (CDKs), motivating extensive research into CDK targeting small-molecule drugs as cancer therapeutics. Here we use combinatorial CRISPR/Cas9 perturbations to uncover an extensive network of functional interdependencies among CDKs and related factors, identifying 43 synthetic-lethal and 12 synergistic interactions. We dissect CDK perturbations using single-cell RNAseq, for which we develop a novel computational framework to precisely quantify cell-cycle effects and diverse cell states orchestrated by specific CDKs. While pairwise disruption of CDK4/6 is synthetic-lethal, only CDK6 is required for normal cell-cycle progression and transcriptional activation. Multiple CDKs (CDK1/7/9/12) are synthetic-lethal in combination with PRMT5, independent of cell-cycle control. In-depth analysis of mRNA expression and splicing patterns provides multiple lines of evidence that the CDK-PRMT5 dependency is due to aberrant transcriptional regulation resulting in premature termination. These inter-dependencies translate to drug-drug synergies, with therapeutic implications in cancer and other diseases.
Collapse
Affiliation(s)
- Kyle Ford
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Brenton P Munson
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Samson H Fong
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Rebecca Panwala
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Wai Keung Chu
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | - Joseph Rainaldi
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
- Biomedical Sciences Program, University of California San Diego, La Jolla, CA, 92093, USA
| | - Nongluk Plongthongkum
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | | | | | - Dario Meluzzi
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Jason F Kreisberg
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | | | - Todd VanArsdale
- Pfizer Inc, 10555 Science Center Drive, San Diego, CA, 92121, USA
| | - Thomas Paul
- Pfizer Inc, 10555 Science Center Drive, San Diego, CA, 92121, USA
| | - Pablo Tamayo
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Kun Zhang
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA
| | | | - Prashant Mali
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Trey Ideker
- Department of Bioengineering, University of California San Diego, La Jolla, CA, 92093, USA.
- Department of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
| |
Collapse
|
6
|
Muralimanoharan S, Shamby R, Stansbury N, Schenken R, de la Pena Avalos B, Javanmardi S, Dray E, Sung P, Boyer TG. Aberrant R-loop-induced replication stress in MED12-mutant uterine fibroids. Sci Rep 2022; 12:6169. [PMID: 35418189 PMCID: PMC9008039 DOI: 10.1038/s41598-022-10188-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/31/2022] [Indexed: 11/09/2022] Open
Abstract
Uterine fibroid (UF) driver mutations in Mediator complex subunit 12 (MED12) trigger genomic instability and tumor development through unknown mechanisms. Herein, we show that MED12 mutations trigger aberrant R-loop-induced replication stress, suggesting a possible route to genomic instability and a novel therapeutic vulnerability in this dominant UF subclass. Immunohistochemical analyses of patient-matched tissue samples revealed that MED12 mutation-positive UFs, compared to MED12 mutation-negative UFs and myometrium, exhibited significantly higher levels of R-loops and activated markers of Ataxia Telangiectasia and Rad3-related (ATR) kinase-dependent replication stress signaling in situ. Single molecule DNA fiber analysis revealed that primary cells from MED12 mutation-positive UFs, compared to those from patient-matched MED12 mutation-negative UFs and myometrium, exhibited defects in replication fork dynamics, including reduced fork speeds, increased and decreased numbers of stalled and restarted forks, respectively, and increased asymmetrical bidirectional forks. Notably, these phenotypes were recapitulated and functionally linked in cultured uterine smooth muscle cells following chemical inhibition of Mediator-associated CDK8/19 kinase activity that is known to be disrupted by UF driver mutations in MED12. Thus, Mediator kinase inhibition triggered enhanced R-loop formation and replication stress leading to an S-phase cell cycle delay, phenotypes that were rescued by overexpression of the R-loop resolving enzyme RNaseH. Altogether, these findings reveal MED12-mutant UFs to be uniquely characterized by aberrant R-loop induced replication stress, suggesting a possible basis for genomic instability and new avenues for therapeutic intervention that involve the replication stress phenotype in this dominant UF subtype.
Collapse
Affiliation(s)
- Sribalasubashini Muralimanoharan
- Department of Molecular Medicine, UT Health San Antonio, STRF, 8210 Floyd Curl Drive, Mail Code 8257, San Antonio, TX, 78229-3900, USA
| | - Ross Shamby
- Department of Molecular Medicine, UT Health San Antonio, STRF, 8210 Floyd Curl Drive, Mail Code 8257, San Antonio, TX, 78229-3900, USA
| | - Nicholas Stansbury
- Department of Obstetrics and Gynecology, UT Health San Antonio, San Antonio, TX, USA
| | - Robert Schenken
- Department of Obstetrics and Gynecology, UT Health San Antonio, San Antonio, TX, USA
| | | | - Samin Javanmardi
- Department of Molecular Medicine, UT Health San Antonio, STRF, 8210 Floyd Curl Drive, Mail Code 8257, San Antonio, TX, 78229-3900, USA
| | - Eloise Dray
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Thomas G Boyer
- Department of Molecular Medicine, UT Health San Antonio, STRF, 8210 Floyd Curl Drive, Mail Code 8257, San Antonio, TX, 78229-3900, USA.
| |
Collapse
|
7
|
Gao Y, Volegova M, Nasholm N, Das S, Kwiatkowski N, Abraham BJ, Zhang T, Gray NS, Gustafson C, Krajewska M, George RE. Synergistic Anti-Tumor Effect of Combining Selective CDK7 and BRD4 Inhibition in Neuroblastoma. Front Oncol 2022; 11:773186. [PMID: 35198433 PMCID: PMC8859926 DOI: 10.3389/fonc.2021.773186] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 12/21/2021] [Indexed: 12/20/2022] Open
Abstract
PURPOSE Cyclin-dependent kinases (CDKs) that have critical roles in RNA polymerase II (Pol II)-mediated gene transcription are emerging as therapeutic targets in cancer. We have previously shown that THZ1, a covalent inhibitor of CDKs 7/12/13, leads to cytotoxicity in MYCN-amplified neuroblastoma through the downregulation of super-enhancer-associated transcriptional upregulation. Here we determined the effects of YKL-5-124, a novel covalent inhibitor with greater selectivity for CDK7 in neuroblastoma cells. EXPERIMENTAL DESIGN We tested YKL-5-124 in MYCN-amplified and nonamplified neuroblastoma cells individually and in combination with other inhibitors in cell line and animal models. Cell viability, target validation, effects on cell cycle and transcription were analyzed. RESULTS CDK7 inhibition with YKL-5-124 did not lead to significant cell death, but resulted in aberrant cell cycle progression especially in MYCN-amplified cells. Unlike THZ1, YKL-5-124 had minimal effects on Pol II C-terminal domain phosphorylation, but significantly inhibited that of the CDK1 and CDK2 cell cycle kinases. Combining YKL-5-124 with the BRD4 inhibitor JQ1 resulted in synergistic cytotoxicity. A distinct MYCN-gene expression signature associated with resistance to BRD4 inhibition was suppressed with the combination. The synergy between YKL-5-124 and JQ1 translated into significant tumor regression in cell line and patient-derived xenograft mouse models of neuroblastoma. CONCLUSIONS The combination of CDK7 and BRD4 inhibition provides a therapeutic option for neuroblastoma and suggests that the addition of YKL-5-124 could improve the therapeutic efficacy of JQ1 and delay resistance to BRD4 inhibition.
Collapse
Affiliation(s)
- Yang Gao
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Marina Volegova
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Nicole Nasholm
- Department of Pediatrics, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, United States
| | - Sanjukta Das
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Nicholas Kwiatkowski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
| | - Brian J Abraham
- Department of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN, United States
| | - Tinghu Zhang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
| | - Nathanael S Gray
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States.,Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, United States
| | - Clay Gustafson
- Department of Pediatrics, Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, United States
| | - Malgorzata Krajewska
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Rani E George
- Department of Pediatric Hematology/Oncology, Dana-Farber Cancer Institute and Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| |
Collapse
|
8
|
Veo B, Danis E, Pierce A, Wang D, Fosmire S, Sullivan KD, Joshi M, Khanal S, Dahl N, Karam S, Serkova N, Venkataraman S, Vibhakar R. Transcriptional control of DNA repair networks by CDK7 regulates sensitivity to radiation in MYC-driven medulloblastoma. Cell Rep 2021; 35:109013. [PMID: 33910002 DOI: 10.1016/j.celrep.2021.109013] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 01/22/2021] [Accepted: 03/29/2021] [Indexed: 12/23/2022] Open
Abstract
MYC-driven medulloblastoma is a major therapeutic challenge due to frequent metastasis and a poor 5-year survival rate. MYC gene amplification results in transcriptional dysregulation, proliferation, and survival of malignant cells. To identify therapeutic targets in MYC-amplified medulloblastoma, we employ a CRISPR-Cas9 essentiality screen targeting 1,140 genes. We identify CDK7 as a mediator of medulloblastoma tumorigenesis. Using chemical inhibitors and genetic depletion, we observe cessation of tumor growth in xenograft mouse models and increases in apoptosis. The results are attributed to repression of a core set of MYC-driven transcriptional programs mediating DNA repair. CDK7 inhibition alters RNA polymerase II (RNA Pol II) and MYC association at DNA repair genes. Blocking CDK7 activity sensitizes cells to ionizing radiation leading to accrual of DNA damage, extending survival and tumor latency in xenograft mouse models. Our studies establish the selective inhibition of MYC-driven medulloblastoma by CDK7 inhibition combined with radiation as a viable therapeutic strategy.
Collapse
Affiliation(s)
- Bethany Veo
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Etienne Danis
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Angela Pierce
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Morgan Adams Foundation Pediatric Brain Tumor Research Program, Children's, Hospital Colorado, Aurora, CO, USA
| | - Dong Wang
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Susan Fosmire
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | | | | | | | - Nathan Dahl
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Morgan Adams Foundation Pediatric Brain Tumor Research Program, Children's, Hospital Colorado, Aurora, CO, USA
| | - Sana Karam
- Department of Radiation Oncology, University of Colorado Denver, Aurora, CO, USA
| | - Natalie Serkova
- Department of Radiology, University of Colorado Denver, Aurora, CO, USA
| | - Sujatha Venkataraman
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Morgan Adams Foundation Pediatric Brain Tumor Research Program, Children's, Hospital Colorado, Aurora, CO, USA
| | - Rajeev Vibhakar
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Morgan Adams Foundation Pediatric Brain Tumor Research Program, Children's, Hospital Colorado, Aurora, CO, USA; Department of Neurosurgery, University of Colorado Denver, Aurora, CO, USA.
| |
Collapse
|
9
|
Selective inhibition of CDK7 reveals high-confidence targets and new models for TFIIH function in transcription. Genes Dev 2020; 34:1452-1473. [PMID: 33060135 PMCID: PMC7608751 DOI: 10.1101/gad.341545.120] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/18/2020] [Indexed: 12/27/2022]
Abstract
In this study, Rimel et al. set out to investigate the roles of CDK7 in transcription. Using SILAC-based phosphoproteomics with transcriptomics and biochemical assays, the authors identified high-confidence CDK7 substrates, a surprisingly widespread requirement for CDK7 activity in splicing, and unexpected aspects of CDK7 kinase regulation that involve its association with TFIIH. CDK7 associates with the 10-subunit TFIIH complex and regulates transcription by phosphorylating the C-terminal domain (CTD) of RNA polymerase II (RNAPII). Few additional CDK7 substrates are known. Here, using the covalent inhibitor SY-351 and quantitative phosphoproteomics, we identified CDK7 kinase substrates in human cells. Among hundreds of high-confidence targets, the vast majority are unique to CDK7 (i.e., distinct from other transcription-associated kinases), with a subset that suggest novel cellular functions. Transcription-associated factors were predominant CDK7 substrates, including SF3B1, U2AF2, and other splicing components. Accordingly, widespread and diverse splicing defects, such as alternative exon inclusion and intron retention, were characterized in CDK7-inhibited cells. Combined with biochemical assays, we establish that CDK7 directly activates other transcription-associated kinases CDK9, CDK12, and CDK13, invoking a “master regulator” role in transcription. We further demonstrate that TFIIH restricts CDK7 kinase function to the RNAPII CTD, whereas other substrates (e.g., SPT5 and SF3B1) are phosphorylated by the three-subunit CDK-activating kinase (CAK; CCNH, MAT1, and CDK7). These results suggest new models for CDK7 function in transcription and implicate CAK dissociation from TFIIH as essential for kinase activation. This straightforward regulatory strategy ensures CDK7 activation is spatially and temporally linked to transcription, and may apply toward other transcription-associated kinases.
Collapse
|
10
|
Dissecting the Pol II transcription cycle and derailing cancer with CDK inhibitors. Nat Chem Biol 2020; 16:716-724. [PMID: 32572259 DOI: 10.1038/s41589-020-0563-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 05/07/2020] [Indexed: 12/16/2022]
Abstract
Largely non-overlapping sets of cyclin-dependent kinases (CDKs) regulate cell division and RNA polymerase II (Pol II)-dependent transcription. Here we review the molecular mechanisms by which specific CDKs are thought to act at discrete steps in the transcription cycle and describe the recent emergence of transcriptional CDKs as promising drug targets in cancer. We emphasize recent advances in understanding the transcriptional CDK network that were facilitated by development and deployment of small-molecule inhibitors with increased selectivity for individual CDKs. Unexpectedly, several of these compounds have also shown selectivity in killing cancer cells, despite the seemingly universal involvement of their target CDKs during transcription in all cells. Finally, we describe remaining and emerging challenges in defining functions of individual CDKs in transcription and co-transcriptional processes and in leveraging CDK inhibition for therapeutic purposes.
Collapse
|
11
|
Diab S, Yu M, Wang S. CDK7 Inhibitors in Cancer Therapy: The Sweet Smell of Success? J Med Chem 2020; 63:7458-7474. [DOI: 10.1021/acs.jmedchem.9b01985] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Sarah Diab
- School of Pharmacy, Lebanese American University, P.O. Box 36, Byblos, Lebanon
| | - Mingfeng Yu
- Drug Discovery and Development, University of South Australia Cancer Research Institute, Adelaide, SA 5000, Australia
| | - Shudong Wang
- Drug Discovery and Development, University of South Australia Cancer Research Institute, Adelaide, SA 5000, Australia
| |
Collapse
|
12
|
Zhang H, Christensen CL, Dries R, Oser MG, Deng J, Diskin B, Li F, Pan Y, Zhang X, Yin Y, Papadopoulos E, Pyon V, Thakurdin C, Kwiatkowski N, Jani K, Rabin AR, Castro DM, Chen T, Silver H, Huang Q, Bulatovic M, Dowling CM, Sundberg B, Leggett A, Ranieri M, Han H, Li S, Yang A, Labbe KE, Almonte C, Sviderskiy VO, Quinn M, Donaghue J, Wang ES, Zhang T, He Z, Velcheti V, Hammerman PS, Freeman GJ, Bonneau R, Kaelin WG, Sutherland KD, Kersbergen A, Aguirre AJ, Yuan GC, Rothenberg E, Miller G, Gray NS, Wong KK. CDK7 Inhibition Potentiates Genome Instability Triggering Anti-tumor Immunity in Small Cell Lung Cancer. Cancer Cell 2020; 37:37-54.e9. [PMID: 31883968 PMCID: PMC7277075 DOI: 10.1016/j.ccell.2019.11.003] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 09/23/2019] [Accepted: 11/22/2019] [Indexed: 12/19/2022]
Abstract
Cyclin-dependent kinase 7 (CDK7) is a central regulator of the cell cycle and gene transcription. However, little is known about its impact on genomic instability and cancer immunity. Using a selective CDK7 inhibitor, YKL-5-124, we demonstrated that CDK7 inhibition predominately disrupts cell-cycle progression and induces DNA replication stress and genome instability in small cell lung cancer (SCLC) while simultaneously triggering immune-response signaling. These tumor-intrinsic events provoke a robust immune surveillance program elicited by T cells, which is further enhanced by the addition of immune-checkpoint blockade. Combining YKL-5-124 with anti-PD-1 offers significant survival benefit in multiple highly aggressive murine models of SCLC, providing a rationale for new combination regimens consisting of CDK7 inhibitors and immunotherapies.
Collapse
Affiliation(s)
- Hua Zhang
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA.
| | | | - Ruben Dries
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Matthew G Oser
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Jiehui Deng
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Brian Diskin
- S. Arthur Localio Laboratory, Department of Surgery, New York University School of Medicine, New York, NY 10016, USA
| | - Fei Li
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Yuanwang Pan
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Xuzhu Zhang
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Yandong Yin
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - Eleni Papadopoulos
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Val Pyon
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Cassandra Thakurdin
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Nicholas Kwiatkowski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Kandarp Jani
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Alexandra R Rabin
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Dayanne M Castro
- Departments of Biology and Computer Science, Center for Genomics and Systems Biology, New York University, New York, NY 10010, USA
| | - Ting Chen
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Heather Silver
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Qingyuan Huang
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Mirna Bulatovic
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Catríona M Dowling
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Belen Sundberg
- S. Arthur Localio Laboratory, Department of Surgery, New York University School of Medicine, New York, NY 10016, USA
| | - Alan Leggett
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Michela Ranieri
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Han Han
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Shuai Li
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Annan Yang
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Kristen E Labbe
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Christina Almonte
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Vladislav O Sviderskiy
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - Max Quinn
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Jack Donaghue
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Eric S Wang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Tinghu Zhang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Zhixiang He
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Vamsidhar Velcheti
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA
| | - Peter S Hammerman
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Gordon J Freeman
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Richard Bonneau
- Departments of Biology and Computer Science, Center for Genomics and Systems Biology, New York University, New York, NY 10010, USA
| | - William G Kaelin
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Kate D Sutherland
- Cancer Biology and Stem Cells Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
| | - Ariena Kersbergen
- Cancer Biology and Stem Cells Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Andrew J Aguirre
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Guo-Cheng Yuan
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016, USA
| | - George Miller
- S. Arthur Localio Laboratory, Department of Surgery, New York University School of Medicine, New York, NY 10016, 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 02215, USA.
| | - Kwok-Kin Wong
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, NY 10016, USA.
| |
Collapse
|
13
|
Selective Kinase Inhibition Shows That Bur1 (Cdk9) Phosphorylates the Rpb1 Linker In Vivo. Mol Cell Biol 2019; 39:MCB.00602-18. [PMID: 31085683 PMCID: PMC6639251 DOI: 10.1128/mcb.00602-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Accepted: 05/03/2019] [Indexed: 12/14/2022] Open
Abstract
Cyclin-dependent kinases play multiple roles in RNA polymerase II transcription. Cdk7/Kin28, Cdk9/Bur1, and Cdk12/Ctk1 phosphorylate the polymerase and other factors to drive the dynamic exchange of initiation and elongation complex components over the transcription cycle. We engineered strains of the yeast Saccharomyces cerevisiae for rapid, specific inactivation of individual kinases by addition of a covalent inhibitor. While effective, the sensitized kinases can display some idiosyncrasies, and inhibition can be surprisingly transient. As expected, inhibition of Cdk7/Kin28 blocked phosphorylation of the Rpb1 C-terminal domain heptad repeats at serines 5 and 7, the known target sites. However, serine 2 phosphorylation was also abrogated, supporting an obligatory sequential phosphorylation mechanism. Consistent with our previous results using gene deletions, Cdk12/Ctk1 is the predominant kinase responsible for serine 2 phosphorylation. Phosphorylation of the Rpb1 linker enhances binding of the Spt6 tandem SH2 domain, and here we show that Bur1/Cdk9 is the kinase responsible for these modifications in vivo.
Collapse
|
14
|
Olson CM, Liang Y, Leggett A, Park WD, Li L, Mills CE, Elsarrag SZ, Ficarro SB, Zhang T, Düster R, Geyer M, Sim T, Marto JA, Sorger PK, Westover KD, Lin CY, Kwiatkowski N, Gray NS. Development of a Selective CDK7 Covalent Inhibitor Reveals Predominant Cell-Cycle Phenotype. Cell Chem Biol 2019; 26:792-803.e10. [PMID: 30905681 DOI: 10.1016/j.chembiol.2019.02.012] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/19/2018] [Accepted: 02/18/2019] [Indexed: 02/06/2023]
Abstract
Cyclin-dependent kinase 7 (CDK7) regulates both cell cycle and transcription, but its precise role remains elusive. We previously described THZ1, a CDK7 inhibitor, which dramatically inhibits superenhancer-associated gene expression. However, potent CDK12/13 off-target activity obscured CDK7s contribution to this phenotype. Here, we describe the discovery of a highly selective covalent CDK7 inhibitor. YKL-5-124 causes arrest at the G1/S transition and inhibition of E2F-driven gene expression; these effects are rescued by a CDK7 mutant unable to covalently engage YKL-5-124, demonstrating on-target specificity. Unlike THZ1, treatment with YKL-5-124 resulted in no change to RNA polymerase II C-terminal domain phosphorylation; however, inhibition could be reconstituted by combining YKL-5-124 and THZ531, a selective CDK12/13 inhibitor, revealing potential redundancies in CDK control of gene transcription. These findings highlight the importance of CDK7/12/13 polypharmacology for anti-cancer activity of THZ1 and posit that selective inhibition of CDK7 may be useful for treatment of cancers marked by E2F misregulation.
Collapse
Affiliation(s)
- Calla M Olson
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA; Therapeutic Innovation Center (THINC@BCM), Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna & Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yanke Liang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Alan Leggett
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Woojun D Park
- Department of Molecular & Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Lianbo Li
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Caitlin E Mills
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston MA 02115, USA
| | - Selma Z Elsarrag
- Department of Molecular & Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Scott B Ficarro
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA; Blais Proteomics Center, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Tinghu Zhang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA
| | - Robert Düster
- Institute of Structural Biology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Matthias Geyer
- Institute of Structural Biology, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Taebo Sim
- Chemical Kinomics Research Center, Korea Institute of Science and Technology (KIST), Seoul 02792, Korea; KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-701, Korea
| | - Jarrod A Marto
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA; Blais Proteomics Center, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Peter K Sorger
- Laboratory of Systems Pharmacology, Harvard Medical School, Boston MA 02115, USA
| | - Ken D Westover
- Departments of Biochemistry and Radiation Oncology, The University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA
| | - Charles Y Lin
- Therapeutic Innovation Center (THINC@BCM), Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Verna & Marrs McLean Department of Biochemistry & Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA; Department of Molecular & Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Nicholas Kwiatkowski
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA.
| | - Nathanael S Gray
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; Department of Biology Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02215, USA.
| |
Collapse
|
15
|
Kolesnikova O, Radu L, Poterszman A. TFIIH: A multi-subunit complex at the cross-roads of transcription and DNA repair. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 115:21-67. [PMID: 30798933 DOI: 10.1016/bs.apcsb.2019.01.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Transcription factor IIH (TFIIH) is a multiprotein complex involved in both eukaryotic transcription and DNA repair, revealing a tight connection between these two processes. Composed of 10 subunits, it can be resolved into a 7-subunits core complex with the XPB translocase and the XPD helicase, and the 3-subunits kinase complex CAK, which also exists as a free complex with a distinct function. Initially identified as basal transcription factor, TFIIH also participates in transcription regulation and plays a key role in nucleotide excision repair (NER) for opening DNA at damaged sites, lesion verification and recruitment of additional repair factors. Our understanding of TFIIH function in eukaryotic cells has greatly benefited from studies of the genetic rare diseases xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD), that are not only characterized by cancer and aging predispositions but also by neurological and developmental defects. Although much remains unknown about TFIIH function, significant progresses have been done regarding the structure of the complex, the functions of its catalytic subunits and the multiple roles of the regulatory core-TFIIH subunits. This review provides a non-exhaustive survey of key discoveries on the structure and function of this pivotal factor, which can be considered as a promising target for therapeutic strategies.
Collapse
Affiliation(s)
- Olga Kolesnikova
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Laura Radu
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France; Université de Strasbourg, Illkirch, France
| | - Arnaud Poterszman
- Institut de Génétique et de Biologie Moléculaire et Cellulaire Illkirch Cedex, C.U. Strasbourg, France; Centre National de la Recherche Scientifique, UMR7104, Illkirch, France; Institut National de la Santé et de la Recherche Médicale, U1258, Illkirch, France; Université de Strasbourg, Illkirch, France.
| |
Collapse
|
16
|
Nemec CM, Singh AK, Ali A, Tseng SC, Syal K, Ringelberg KJ, Ho YH, Hintermair C, Ahmad MF, Kar RK, Gasch AP, Akhtar MS, Eick D, Ansari AZ. Noncanonical CTD kinases regulate RNA polymerase II in a gene-class-specific manner. Nat Chem Biol 2018; 15:123-131. [PMID: 30598543 PMCID: PMC6339578 DOI: 10.1038/s41589-018-0194-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 11/09/2018] [Indexed: 11/09/2022]
Abstract
Phosphorylation of the carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) governs stage-specific interactions with different cellular machines. The CTD consists of Y1S2P3T4S5P6S7 heptad repeats, and sequential phosphorylations of Ser7, Ser5 and Ser2 occur universally across Pol II-transcribed genes. Phosphorylation of Thr4, however, appears to selectively modulate transcription of specific classes of genes. Here, we identify 10 new Thr4 kinases from different kinase structural groups. Irreversible chemical inhibition of the most active Thr4 kinase, Hrr25, reveals a novel role for this kinase in transcription termination of specific class of noncoding snoRNA genes. Genome-wide profiles of Hrr25 reveal a selective enrichment at 3ʹ regions of noncoding genes that display termination defects. Importantly, phospho-Thr4 marks placed by Hrr25 are recognized by Rtt103, a key component of the termination machinery. Our results suggest that these uncommon CTD kinases selectively place phospho-Thr4 marks to regulate expression of targeted genes.
Collapse
Affiliation(s)
- Corey M Nemec
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Amit K Singh
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Lucknow, India
| | - Asfa Ali
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Sandra C Tseng
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Kirtimaan Syal
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Yi-Hsuan Ho
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Corinna Hintermair
- Department of Molecular Epigenetics, Helmholtz Center Munich, Center of Integrated Protein Science, Munich, Germany
| | - Mohammad Faiz Ahmad
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Rajesh Kumar Kar
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Audrey P Gasch
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Md Sohail Akhtar
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Lucknow, India.,Academy of Scientific and Innovative Research, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Lucknow, India
| | - Dirk Eick
- Department of Molecular Epigenetics, Helmholtz Center Munich, Center of Integrated Protein Science, Munich, Germany
| | - Aseem Z Ansari
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
| |
Collapse
|
17
|
Abstract
The Mediator-associated kinases CDK8 and CDK19 function in the context of three additional proteins: CCNC and MED12, which activate CDK8/CDK19 kinase function, and MED13, which enables their association with the Mediator complex. The Mediator kinases affect RNA polymerase II (pol II) transcription indirectly, through phosphorylation of transcription factors and by controlling Mediator structure and function. In this review, we discuss cellular roles of the Mediator kinases and mechanisms that enable their biological functions. We focus on sequence-specific, DNA-binding transcription factors and other Mediator kinase substrates, and how CDK8 or CDK19 may enable metabolic and transcriptional reprogramming through enhancers and chromatin looping. We also summarize Mediator kinase inhibitors and their therapeutic potential. Throughout, we note conserved and divergent functions between yeast and mammalian CDK8, and highlight many aspects of kinase module function that remain enigmatic, ranging from potential roles in pol II promoter-proximal pausing to liquid-liquid phase separation.
Collapse
Affiliation(s)
- Charli B Fant
- a Department of Biochemistry , University of Colorado , Boulder , CO , USA
| | - Dylan J Taatjes
- a Department of Biochemistry , University of Colorado , Boulder , CO , USA
| |
Collapse
|
18
|
Fisher RP. Cdk7: a kinase at the core of transcription and in the crosshairs of cancer drug discovery. Transcription 2018; 10:47-56. [PMID: 30488763 DOI: 10.1080/21541264.2018.1553483] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The transcription cycle of RNA polymerase II (Pol II) is regulated by a set of cyclin-dependent kinases (CDKs). Cdk7, associated with the transcription initiation factor TFIIH, is both an effector CDK that phosphorylates Pol II and other targets within the transcriptional machinery, and a CDK-activating kinase (CAK) for at least one other essential CDK involved in transcription. Recent studies have illuminated Cdk7 functions that are executed throughout the Pol II transcription cycle, from promoter clearance and promoter-proximal pausing, to co-transcriptional chromatin modification in gene bodies, to mRNA 3´-end formation and termination. Cdk7 has also emerged as a target of small-molecule inhibitors that show promise in the treatment of cancer and inflammation. The challenges now are to identify the relevant targets of Cdk7 at each step of the transcription cycle, and to understand how heightened dependence on an essential CDK emerges in cancer, and might be exploited therapeutically.
Collapse
Affiliation(s)
- Robert P Fisher
- a Department of Oncological Sciences , Icahn School of Medicine at Mount Sinai , New York , NY , USA
| |
Collapse
|
19
|
Mediator, known as a coactivator, can act in transcription initiation in an activator-independent manner in vivo. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:687-696. [DOI: 10.1016/j.bbagrm.2018.07.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 06/28/2018] [Accepted: 07/04/2018] [Indexed: 01/20/2023]
|
20
|
Rimel JK, Taatjes DJ. The essential and multifunctional TFIIH complex. Protein Sci 2018; 27:1018-1037. [PMID: 29664212 PMCID: PMC5980561 DOI: 10.1002/pro.3424] [Citation(s) in RCA: 82] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 04/04/2018] [Accepted: 04/05/2018] [Indexed: 12/19/2022]
Abstract
TFIIH is a 10‐subunit complex that regulates RNA polymerase II (pol II) transcription but also serves other important biological roles. Although much remains unknown about TFIIH function in eukaryotic cells, much progress has been made even in just the past few years, due in part to technological advances (e.g. cryoEM and single molecule methods) and the development of chemical inhibitors of TFIIH enzymes. This review focuses on the major cellular roles for TFIIH, with an emphasis on TFIIH function as a regulator of pol II transcription. We describe the structure of TFIIH and its roles in pol II initiation, promoter‐proximal pausing, elongation, and termination. We also discuss cellular roles for TFIIH beyond transcription (e.g. DNA repair, cell cycle regulation) and summarize small molecule inhibitors of TFIIH and diseases associated with defects in TFIIH structure and function.
Collapse
Affiliation(s)
- Jenna K Rimel
- Department of Chemistry & Biochemistry, University of Colorado, Boulder, Colorado, 80303
| | - Dylan J Taatjes
- Department of Chemistry & Biochemistry, University of Colorado, Boulder, Colorado, 80303
| |
Collapse
|
21
|
Ebmeier CC, Erickson B, Allen BL, Allen MA, Kim H, Fong N, Jacobsen JR, Liang K, Shilatifard A, Dowell RD, Old WM, Bentley DL, Taatjes DJ. Human TFIIH Kinase CDK7 Regulates Transcription-Associated Chromatin Modifications. Cell Rep 2018; 20:1173-1186. [PMID: 28768201 DOI: 10.1016/j.celrep.2017.07.021] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 06/30/2017] [Accepted: 07/11/2017] [Indexed: 01/24/2023] Open
Abstract
CDK7 phosphorylates the RNA polymerase II (pol II) C-terminal domain CTD and activates the P-TEFb-associated kinase CDK9, but its regulatory roles remain obscure. Here, using human CDK7 analog-sensitive (CDK7as) cells, we observed reduced capping enzyme recruitment, increased pol II promoter-proximal pausing, and defective termination at gene 3' ends upon CDK7 inhibition. We also noted that CDK7 regulates chromatin modifications downstream of transcription start sites. H3K4me3 spreading was restricted at gene 5' ends and H3K36me3 was displaced toward gene 3' ends in CDK7as cells. Mass spectrometry identified factors that bound TFIIH-phosphorylated versus P-TEFb-phosphorylated CTD (versus unmodified); capping enzymes and H3K4 methyltransferase complexes, SETD1A/B, selectively bound phosphorylated CTD, and the H3K36 methyltransferase SETD2 specifically bound P-TEFb-phosphorylated CTD. Moreover, TFIIH-phosphorylated CTD stimulated SETD1A/B activity toward nucleosomes, revealing a mechanistic basis for CDK7 regulation of H3K4me3 spreading. Collectively, these results implicate a CDK7-dependent "CTD code" that regulates chromatin marks in addition to RNA processing and pol II pausing.
Collapse
Affiliation(s)
- Christopher C Ebmeier
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80303, USA; Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Benjamin Erickson
- Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Benjamin L Allen
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80303, USA
| | - Mary A Allen
- BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA; Linda Crnic Institute for Down Syndrome, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Hyunmin Kim
- Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Nova Fong
- Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jeremy R Jacobsen
- Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Kaiwei Liang
- Department of Biochemistry & Molecular Genetics, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Ali Shilatifard
- Department of Biochemistry & Molecular Genetics, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Robin D Dowell
- Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA; Linda Crnic Institute for Down Syndrome, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - William M Old
- Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Linda Crnic Institute for Down Syndrome, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - David L Bentley
- Department Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA.
| | - Dylan J Taatjes
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80303, USA.
| |
Collapse
|
22
|
Pharmacological perturbation of CDK9 using selective CDK9 inhibition or degradation. Nat Chem Biol 2017; 14:163-170. [PMID: 29251720 DOI: 10.1038/nchembio.2538] [Citation(s) in RCA: 336] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 11/09/2017] [Indexed: 01/06/2023]
Abstract
Cyclin-dependent kinase 9 (CDK9), an important regulator of transcriptional elongation, is a promising target for cancer therapy, particularly for cancers driven by transcriptional dysregulation. We characterized NVP-2, a selective ATP-competitive CDK9 inhibitor, and THAL-SNS-032, a selective CDK9 degrader consisting of a CDK-binding SNS-032 ligand linked to a thalidomide derivative that binds the E3 ubiquitin ligase Cereblon (CRBN). To our surprise, THAL-SNS-032 induced rapid degradation of CDK9 without affecting the levels of other SNS-032 targets. Moreover, the transcriptional changes elicited by THAL-SNS-032 were more like those caused by NVP-2 than those induced by SNS-032. Notably, compound washout did not significantly reduce levels of THAL-SNS-032-induced apoptosis, suggesting that CDK9 degradation had prolonged cytotoxic effects compared with CDK9 inhibition. Thus, our findings suggest that thalidomide conjugation represents a promising strategy for converting multi-targeted inhibitors into selective degraders and reveal that kinase degradation can induce distinct pharmacological effects compared with inhibition.
Collapse
|
23
|
Different phosphoisoforms of RNA polymerase II engage the Rtt103 termination factor in a structurally analogous manner. Proc Natl Acad Sci U S A 2017; 114:E3944-E3953. [PMID: 28465432 DOI: 10.1073/pnas.1700128114] [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] [Indexed: 01/08/2023] Open
Abstract
The carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II (Pol II) orchestrates dynamic recruitment of specific cellular machines during different stages of transcription. Signature phosphorylation patterns of Y1S2P3T4S5P6S7 heptapeptide repeats of the CTD engage specific "readers." Whereas phospho-Ser5 and phospho-Ser2 marks are ubiquitous, phospho-Thr4 is reported to only impact specific genes. Here, we identify a role for phospho-Thr4 in transcription termination at noncoding small nucleolar RNA (snoRNA) genes. Quantitative proteomics reveals an interactome of known readers as well as protein complexes that were not known to rely on Thr4 for association with Pol II. The data indicate a key role for Thr4 in engaging the machinery used for transcription elongation and termination. We focus on Rtt103, a protein that binds phospho-Ser2 and phospho-Thr4 marks and facilitates transcription termination at protein-coding genes. To elucidate how Rtt103 engages two distinct CTD modifications that are differentially enriched at noncoding genes, we relied on NMR analysis of Rtt103 in complex with phospho-Thr4- or phospho-Ser2-bearing CTD peptides. The structural data reveal that Rtt103 interacts with phospho-Thr4 in a manner analogous to its interaction with phospho-Ser2-modified CTD. The same set of hydrogen bonds involving either the oxygen on phospho-Thr4 and the hydroxyl on Ser2, or the phosphate on Ser2 and the Thr4 hydroxyl, can be formed by rotation of an arginine side chain, leaving the intermolecular interface otherwise unperturbed. This economy of design enables Rtt103 to engage Pol II at distinct sets of genes with differentially enriched CTD marks.
Collapse
|
24
|
Singh AK, Rastogi S, Shukla H, Asalam M, Rath SK, Akhtar MS. Cdc15 Phosphorylates the C-terminal Domain of RNA Polymerase II for Transcription during Mitosis. J Biol Chem 2017; 292:5507-5518. [PMID: 28202544 DOI: 10.1074/jbc.m116.761056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/12/2017] [Indexed: 11/06/2022] Open
Abstract
In eukaryotes, the basal transcription in interphase is orchestrated through the regulation by kinases (Kin28, Bur1, and Ctk1) and phosphatases (Ssu72, Rtr1, and Fcp1), which act through the post-translational modification of the C-terminal domain (CTD) of the largest subunit of RNA polymerase II. The CTD comprises the repeated Tyr-Ser-Pro-Thr-Ser-Pro-Ser motif with potential epigenetic modification sites. Despite the observation of transcription and periodic expression of genes during mitosis with entailing CTD phosphorylation and dephosphorylation, the associated CTD specific kinase(s) and its role in transcription remains unknown. Here we have identified Cdc15 as a potential kinase phosphorylating Ser-2 and Ser-5 of CTD for transcription during mitosis in the budding yeast. The phosphorylation of CTD by Cdc15 is independent of any prior Ser phosphorylation(s). The inactivation of Cdc15 causes reduction of global CTD phosphorylation during mitosis and affects the expression of genes whose transcript levels peak during mitosis. Cdc15 also influences the complete transcription of clb2 gene and phosphorylates Ser-5 at the promoter and Ser-2 toward the 3' end of the gene. The observation that Cdc15 could phosphorylate Ser-5, as well as Ser-2, during transcription in mitosis is in contrast to the phosphorylation marks put by the kinases in interphase (G1, S, and G2), where Cdck7/Kin28 phosphorylates Ser-5 at promoter and Bur1/Ctk1 phosphorylates Ser-2 at the 3' end of the genes.
Collapse
Affiliation(s)
| | | | | | - Mohd Asalam
- From the Molecular and Structural Biology Division
| | - Srikanta Kumar Rath
- the Toxicology Division, Council of Scientific and Industrial Research (CSIR)-Central Drug Research Institute, Lucknow PIN 226 031, India and.,the Academy of Scientific and Innovative Research, New Delhi 110025, India
| | - Md Sohail Akhtar
- From the Molecular and Structural Biology Division, .,the Academy of Scientific and Innovative Research, New Delhi 110025, India
| |
Collapse
|
25
|
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.
Collapse
Affiliation(s)
- Robert P Fisher
- a Department of Oncological Sciences , Icahn School of Medicine at Mount Sinai , New York , NY , USA
| |
Collapse
|
26
|
Deshmukh AS, Mitra P, Maruthi M. Cdk7 mediates RPB1-driven mRNA synthesis in Toxoplasma gondii. Sci Rep 2016; 6:35288. [PMID: 27759017 PMCID: PMC5069487 DOI: 10.1038/srep35288] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 09/28/2016] [Indexed: 11/16/2022] Open
Abstract
Cyclin-dependent kinase 7 in conjunction with CyclinH and Mat1 activates cell cycle CDKs and is a part of the general transcription factor TFIIH. Role of Cdk7 is well characterized in model eukaryotes however its relevance in protozoan parasites has not been investigated. This important regulator of key processes warrants closer examination particularly in this parasite given its unique cell cycle progression and flexible mode of replication. We report functional characterization of TgCdk7 and its partners TgCyclinH and TgMat1. Recombinant Cdk7 displays kinase activity upon binding its cyclin partner and this activity is further enhanced in presence of Mat1. The activated kinase phosphorylates C-terminal domain of TgRPB1 suggesting its role in parasite transcription. Therefore, the function of Cdk7 in CTD phosphorylation and RPB1 mediated transcription was investigated using Cdk7 inhibitor. Unphosphorylated CTD binds promoter DNA while phosphorylation by Cdk7 triggers its dissociation from DNA with implications for transcription initiation. Inhibition of Cdk7 in the parasite led to strong reduction in Serine 5 phosphorylation of TgRPB1-CTD at the promoters of constitutively expressed actin1 and sag1 genes with concomitant reduction of both nascent RNA synthesis and 5′-capped transcripts. Therefore, we provide compelling evidence for crucial role of TgCdk7 kinase activity in mRNA synthesis.
Collapse
Affiliation(s)
| | - Pallabi Mitra
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
| | - Mulaka Maruthi
- Department of Animal Biology, School of Life Sciences, University of Hyderabad, Hyderabad, India
| |
Collapse
|
27
|
The mRNA capping enzyme of Saccharomyces cerevisiae has dual specificity to interact with CTD of RNA Polymerase II. Sci Rep 2016; 6:31294. [PMID: 27503426 PMCID: PMC4977518 DOI: 10.1038/srep31294] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 07/15/2016] [Indexed: 11/08/2022] Open
Abstract
RNA Polymerase II (RNAPII) uniquely possesses an extended carboxy terminal domain (CTD) on its largest subunit, Rpb1, comprising a repetitive Tyr1Ser2Pro3Thr4 Ser5Pro6Ser7 motif with potential phosphorylation sites. The phosphorylation of the CTD serves as a signal for the binding of various transcription regulators for mRNA biogenesis including the mRNA capping complex. In eukaryotes, the 5 prime capping of the nascent transcript is the first detectable mRNA processing event, and is crucial for the productive transcript elongation. The binding of capping enzyme, RNA guanylyltransferases to the transcribing RNAPII is known to be primarily facilitated by the CTD, phosphorylated at Ser5 (Ser5P). Here we report that the Saccharomyces cerevesiae RNA guanylyltransferase (Ceg1) has dual specificity and interacts not only with Ser5P but also with Ser7P of the CTD. The Ser7 of CTD is essential for the unconditional growth and efficient priming of the mRNA capping complex. The Arg159 and Arg185 of Ceg1 are the key residues that interact with the Ser5P, while the Lys175 with Ser7P of CTD. These interactions appear to be in a specific pattern of Ser5PSer7PSer5P in a tri-heptad CTD (YSPTSPPS YSPTSPSP YSPTSPPS) and provide molecular insights into the Ceg1-CTD interaction for mRNA transcription.
Collapse
|
28
|
Engineered Covalent Inactivation of TFIIH-Kinase Reveals an Elongation Checkpoint and Results in Widespread mRNA Stabilization. Mol Cell 2016; 63:433-44. [PMID: 27477907 DOI: 10.1016/j.molcel.2016.06.036] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 05/09/2016] [Accepted: 06/23/2016] [Indexed: 12/25/2022]
Abstract
During transcription initiation, the TFIIH-kinase Kin28/Cdk7 marks RNA polymerase II (Pol II) by phosphorylating the C-terminal domain (CTD) of its largest subunit. Here we describe a structure-guided chemical approach to covalently and specifically inactivate Kin28 kinase activity in vivo. This method of irreversible inactivation recapitulates both the lethal phenotype and the key molecular signatures that result from genetically disrupting Kin28 function in vivo. Inactivating Kin28 impacts promoter release to differing degrees and reveals a "checkpoint" during the transition to productive elongation. While promoter-proximal pausing is not observed in budding yeast, inhibition of Kin28 attenuates elongation-licensing signals, resulting in Pol II accumulation at the +2 nucleosome and reduced transition to productive elongation. Furthermore, upon inhibition, global stabilization of mRNA masks different degrees of reduction in nascent transcription. This study resolves long-standing controversies on the role of Kin28 in transcription and provides a rational approach to irreversibly inhibit other kinases in vivo.
Collapse
|
29
|
Poss ZC, Ebmeier CC, Odell AT, Tangpeerachaikul A, Lee T, Pelish HE, Shair MD, Dowell RD, Old WM, Taatjes DJ. Identification of Mediator Kinase Substrates in Human Cells using Cortistatin A and Quantitative Phosphoproteomics. Cell Rep 2016; 15:436-50. [PMID: 27050516 DOI: 10.1016/j.celrep.2016.03.030] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 02/08/2016] [Accepted: 03/08/2016] [Indexed: 12/22/2022] Open
Abstract
Cortistatin A (CA) is a highly selective inhibitor of the Mediator kinases CDK8 and CDK19. Using CA, we now report a large-scale identification of Mediator kinase substrates in human cells (HCT116). We identified over 16,000 quantified phosphosites including 78 high-confidence Mediator kinase targets within 64 proteins, including DNA-binding transcription factors and proteins associated with chromatin, DNA repair, and RNA polymerase II. Although RNA-seq data correlated with Mediator kinase targets, the effects of CA on gene expression were limited and distinct from CDK8 or CDK19 knockdown. Quantitative proteome analyses, tracking around 7,000 proteins across six time points (0-24 hr), revealed that CA selectively affected pathways implicated in inflammation, growth, and metabolic regulation. Contrary to expectations, increased turnover of Mediator kinase targets was not generally observed. Collectively, these data support Mediator kinases as regulators of chromatin and RNA polymerase II activity and suggest their roles extend beyond transcription to metabolism and DNA repair.
Collapse
Affiliation(s)
- Zachary C Poss
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80303, USA
| | - Christopher C Ebmeier
- Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Aaron T Odell
- Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | | | - Thomas Lee
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80303, USA
| | - Henry E Pelish
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Matthew D Shair
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Robin D Dowell
- Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
| | - William M Old
- Department of Molecular, Cell, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Dylan J Taatjes
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80303, USA.
| |
Collapse
|
30
|
Wang Y, Zhang T, Kwiatkowski N, Abraham BJ, Lee TI, Xie S, Yuzugullu H, Von T, Li H, Lin Z, Stover DG, Lim E, Wang ZC, Iglehart JD, Young RA, Gray NS, Zhao JJ. CDK7-dependent transcriptional addiction in triple-negative breast cancer. Cell 2015; 163:174-86. [PMID: 26406377 DOI: 10.1016/j.cell.2015.08.063] [Citation(s) in RCA: 314] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 05/27/2015] [Accepted: 08/12/2015] [Indexed: 12/19/2022]
Abstract
Triple-negative breast cancer (TNBC) is a highly aggressive form of breast cancer that exhibits extremely high levels of genetic complexity and yet a relatively uniform transcriptional program. We postulate that TNBC might be highly dependent on uninterrupted transcription of a key set of genes within this gene expression program and might therefore be exceptionally sensitive to inhibitors of transcription. Utilizing kinase inhibitors and CRISPR/Cas9-mediated gene editing, we show here that triple-negative but not hormone receptor-positive breast cancer cells are exceptionally dependent on CDK7, a transcriptional cyclin-dependent kinase. TNBC cells are unique in their dependence on this transcriptional CDK and suffer apoptotic cell death upon CDK7 inhibition. An "Achilles cluster" of TNBC-specific genes is especially sensitive to CDK7 inhibition and frequently associated with super-enhancers. We conclude that CDK7 mediates transcriptional addiction to a vital cluster of genes in TNBC and CDK7 inhibition may be a useful therapy for this challenging cancer.
Collapse
Affiliation(s)
- Yubao Wang
- 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
| | - Nicholas Kwiatkowski
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Brian J Abraham
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Tong Ihn Lee
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Shaozhen Xie
- 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
| | - Haluk Yuzugullu
- 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
| | - Thanh Von
- 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
| | - Heyuan Li
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Ziao Lin
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Daniel G Stover
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Elgene Lim
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Zhigang C Wang
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Surgery, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - J Dirk Iglehart
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02115, USA; Department of Surgery, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Richard A Young
- Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, 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.
| | - Jean J Zhao
- 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.
| |
Collapse
|
31
|
Medler S, Ansari A. Gene looping facilitates TFIIH kinase-mediated termination of transcription. Sci Rep 2015; 5:12586. [PMID: 26286112 PMCID: PMC4541409 DOI: 10.1038/srep12586] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 06/08/2015] [Indexed: 12/14/2022] Open
Abstract
TFIIH is a general transcription factor with kinase and helicase activities. The kinase activity resides in the Kin28 subunit of TFIIH. The role of Kin28 kinase in the early steps of transcription is well established. Here we report a novel role of Kin28 in the termination of transcription. We show that RNAPII reads through a termination signal upon kinase inhibition. Furthermore, the recruitment of termination factors towards the 3′ end of a gene was compromised in the kinase mutant, thus confirming the termination defect. A concomitant decrease in crosslinking of termination factors near the 5′ end of genes was also observed in the kinase-defective mutant. Simultaneous presence of termination factors towards both the ends of a gene is indicative of gene looping; while the loss of termination factor occupancy from the distal ends suggest the abolition of a looped gene conformation. Accordingly, CCC analysis revealed that the looped architecture of genes was severely compromised in the Kin28 kinase mutant. In a looping defective sua7-1 mutant, even the enzymatically active Kin28 kinase could not rescue the termination defect. These results strongly suggest a crucial role of Kin28 kinase-dependent gene looping in the termination of transcription in budding yeast.
Collapse
Affiliation(s)
- Scott Medler
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall Detroit, MI 48202
| | - Athar Ansari
- Department of Biological Sciences, Wayne State University, 5047 Gullen Mall Detroit, MI 48202
| |
Collapse
|
32
|
Mbogning J, Pagé V, Burston J, Schwenger E, Fisher RP, Schwer B, Shuman S, Tanny JC. Functional interaction of Rpb1 and Spt5 C-terminal domains in co-transcriptional histone modification. Nucleic Acids Res 2015; 43:9766-75. [PMID: 26275777 PMCID: PMC4787787 DOI: 10.1093/nar/gkv837] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 08/09/2015] [Indexed: 12/11/2022] Open
Abstract
Transcription by RNA polymerase II (RNAPII) is accompanied by a conserved pattern of histone modifications that plays important roles in regulating gene expression. The establishment of this pattern requires phosphorylation of both Rpb1 (the largest RNAPII subunit) and the elongation factor Spt5 on their respective C-terminal domains (CTDs). Here we interrogated the roles of individual Rpb1 and Spt5 CTD phospho-sites in directing co-transcriptional histone modifications in the fission yeast Schizosaccharomyces pombe. Steady-state levels of methylation at histone H3 lysines 4 (H3K4me) and 36 (H3K36me) were sensitive to multiple mutations of the Rpb1 CTD repeat motif (Y1S2P3T4S5P6S7). Ablation of the Spt5 CTD phospho-site Thr1 reduced H3K4me levels but had minimal effects on H3K36me. Nonetheless, Spt5 CTD mutations potentiated the effects of Rpb1 CTD mutations on H3K36me, suggesting overlapping functions. Phosphorylation of Rpb1 Ser2 by the Cdk12 orthologue Lsk1 positively regulated H3K36me but negatively regulated H3K4me. H3K36me and histone H2B monoubiquitylation required Rpb1 Ser5 but were maintained upon inactivation of Mcs6/Cdk7, the major kinase for Rpb1 Ser5 in vivo, implicating another Ser5 kinase in these regulatory pathways. Our results elaborate the CTD ‘code’ for co-transcriptional histone modifications.
Collapse
Affiliation(s)
- Jean Mbogning
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, H3G 1Y6, Canada
| | - Viviane Pagé
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, H3G 1Y6, Canada
| | - Jillian Burston
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, H3G 1Y6, Canada
| | - Emily Schwenger
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, H3G 1Y6, Canada
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Beate Schwer
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Stewart Shuman
- Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Jason C Tanny
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, H3G 1Y6, Canada
| |
Collapse
|
33
|
Nilson KA, Guo J, Turek ME, Brogie JE, Delaney E, Luse DS, Price DH. THZ1 Reveals Roles for Cdk7 in Co-transcriptional Capping and Pausing. Mol Cell 2015; 59:576-87. [PMID: 26257281 DOI: 10.1016/j.molcel.2015.06.032] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 06/01/2015] [Accepted: 06/23/2015] [Indexed: 12/31/2022]
Abstract
The Cdk7 subunit of TFIIH phosphorylates RNA polymerase II (Pol II) during initiation, and, while recent studies show that inhibition of human Cdk7 negatively influences transcription, the mechanisms involved are unclear. Using in vitro transcription with nuclear extract, we demonstrate that THZ1, a covalent Cdk7 inhibitor, causes defects in Pol II phosphorylation, co-transcriptional capping, promoter proximal pausing, and productive elongation. THZ1 does not affect initiation but blocks essentially all Pol II large subunit C-terminal domain (CTD) phosphorylation. We found that guanylylation of nascent RNAs is length dependent and modulated by a THZ1-sensitive factor present in nuclear extract. THZ1 impacts pausing through a capping-independent block of DSIF and NELF loading. The P-TEFb-dependent transition into productive elongation was also inhibited by THZ1, likely due to loss of DSIF. Capping and pausing were also reduced in THZ1-treated cells. Our results provide mechanistic insights into THZ1 action and how Cdk7 broadly influences transcription and capping.
Collapse
Affiliation(s)
- Kyle A Nilson
- Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA
| | - Jiannan Guo
- Biochemistry Department, University of Iowa, Iowa City, IA 52242, USA
| | - Michael E Turek
- Biochemistry Department, University of Iowa, Iowa City, IA 52242, USA
| | - John E Brogie
- Biochemistry Department, University of Iowa, Iowa City, IA 52242, USA
| | - Elizabeth Delaney
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Donal S Luse
- Department of Cellular and Molecular Medicine, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - David H Price
- Molecular and Cellular Biology Program, University of Iowa, Iowa City, IA 52242, USA; Biochemistry Department, University of Iowa, Iowa City, IA 52242, USA.
| |
Collapse
|
34
|
Fission yeast Cdk7 controls gene expression through both its CAK and C-terminal domain kinase activities. Mol Cell Biol 2015; 35:1480-90. [PMID: 25691663 DOI: 10.1128/mcb.00024-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 02/03/2015] [Indexed: 11/20/2022] Open
Abstract
Cyclin-dependent kinase (Cdk) activation and RNA polymerase II transcription are linked by the Cdk7 kinase, which phosphorylates Cdks as a trimeric Cdk-activating kinase (CAK) complex, and serine 5 within the polymerase II (Pol II) C-terminal domain (CTD) as transcription factor TFIIH-bound CAK. However, the physiological importance of integrating these processes is not understood. Besides the Cdk7 ortholog Mcs6, fission yeast possesses a second CAK, Csk1. The two enzymes have been proposed to act redundantly to activate Cdc2. Using an improved analogue-sensitive Mcs6-as kinase, we show that Csk1 is not a relevant CAK for Cdc2. Further analyses revealed that Csk1 lacks a 20-amino-acid sequence required for its budding yeast counterpart, Cak1, to bind Cdc2. Transcriptome profiling of the Mcs6-as mutant in the presence or absence of the budding yeast Cak1 kinase, in order to uncouple the CTD kinase and CAK activities of Mcs6, revealed an unanticipated role of the CAK branch in the transcriptional control of the cluster of genes implicated in ribosome biogenesis and cell growth. The analysis of a Cdc2 CAK site mutant confirmed these data. Our data show that the Cdk7 kinase modulates transcription through its well-described RNA Pol II CTD kinase activity and also through the Cdc2-activating kinase activity.
Collapse
|
35
|
Abstract
Transcription elongation by RNA polymerase II (RNAP II) involves the coordinated action of numerous regulatory factors. Among these are chromatin-modifying enzymes, which generate a stereotypic and conserved pattern of histone modifications along transcribed genes. This pattern implies a precise coordination between regulators of histone modification and the RNAP II elongation complex. Here I review the pathways and molecular events that regulate co-transcriptional histone modifications. Insight into these events will illuminate the assembly of functional RNAP II elongation complexes and how the chromatin landscape influences their composition and function.
Collapse
Affiliation(s)
- Jason C Tanny
- a Department of Pharmacology and Therapeutics ; McGill University ; Montreal , Canada
| |
Collapse
|
36
|
Rosado-Lugo JD, Hampsey M. The Ssu72 phosphatase mediates the RNA polymerase II initiation-elongation transition. J Biol Chem 2014; 289:33916-26. [PMID: 25339178 DOI: 10.1074/jbc.m114.608695] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Transitions between the different stages of the RNAPII transcription cycle involve the recruitment and exchange of factors, including mRNA capping enzymes, elongation factors, splicing factors, 3'-end-processing complexes, and termination factors. These transitions are coordinated by the dynamic phosphorylation of the C-terminal domain (CTD) of the largest subunit of RNAPII (Rpb1). The CTD is composed of reiterated heptapeptide repeats (Y(1)S(2)P(3)T(4)S(5)P(6)S(7)) that undergo phosphorylation and dephosphorylation as RNAPII transitions through the transcription cycle. An essential phosphatase in this process is Ssu72, which exhibits catalytic specificity for Ser(P)(5) and Ser(P)(7). Ssu72 is unique in that it is specific for Ser(P)(5) in one orientation of the CTD and for Ser(P)(7) when bound in the opposite orientation. Moreover, Ssu72 interacts with components of the initiation machinery and affects start site selection yet is an integral component of the CPF 3'-end-processing complex. Here we provide a comprehensive view of the effects of Ssu72 with respect to its Ser(P)(5) phosphatase activity. We demonstrate that Ssu72 dephosphorylates Ser(P)(5) at the initiation-elongation transition. Furthermore, Ssu72 indirectly affects the levels of Ser(P)(2) during the elongation stage of transcription but does so independent of its catalytic activity.
Collapse
Affiliation(s)
- Jesús D Rosado-Lugo
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - Michael Hampsey
- From the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| |
Collapse
|
37
|
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.
Collapse
|
38
|
Wong KH, Jin Y, Struhl K. TFIIH phosphorylation of the Pol II CTD stimulates mediator dissociation from the preinitiation complex and promoter escape. Mol Cell 2014; 54:601-12. [PMID: 24746699 DOI: 10.1016/j.molcel.2014.03.024] [Citation(s) in RCA: 147] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 02/19/2014] [Accepted: 03/07/2014] [Indexed: 11/30/2022]
Abstract
The transition between transcriptional initiation and elongation by RNA polymerase (Pol) II is associated with phosphorylation of its C-terminal tail (CTD). Depletion of Kin28, the TFIIH subunit that phosphorylates the CTD, does not affect elongation but causes Pol II occupancy profiles to shift upstream in a FACT-independent manner indicative of a defect in promoter escape. Stronger defects in promoter escape are linked to stronger effects on preinitiation complex formation and transcription, suggesting that impairment in promoter escape results in premature dissociation of general factors and Pol II near the promoter. Kin28 has a stronger effect on genes whose transcription is dependent on SAGA as opposed to TFIID. Strikingly, Kin28 depletion causes a dramatic increase in Mediator at the core promoter. These observations suggest that TFIIH phosphorylation of the CTD causes Mediator dissociation, thereby permitting rapid promoter escape of Pol II from the preinitiation complex.
Collapse
Affiliation(s)
- Koon Ho Wong
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Yi Jin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| | - Kevin Struhl
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
39
|
Morishita J, Kang MJ, Fidelin K, Ryoo HD. CDK7 regulates the mitochondrial localization of a tail-anchored proapoptotic protein, Hid. Cell Rep 2013; 5:1481-8. [PMID: 24360962 DOI: 10.1016/j.celrep.2013.11.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/26/2013] [Accepted: 11/15/2013] [Indexed: 01/20/2023] Open
Abstract
The mitochondrial outer membrane is a major site of apoptosis regulation across phyla. Human and C. elegans Bcl-2 family proteins and Drosophila Hid require the C-terminal tail-anchored (TA) sequence in order to insert into the mitochondrial membrane, but it remains unclear whether cytosolic proteins actively regulate the mitochondrial localization of these proteins. Here, we report that the cdk7 complex regulates the mitochondrial localization of Hid and its ability to induce apoptosis. We identified cdk7 through an in vivo RNAi screen of genes required for cell death. Although CDK7 is best known for its role in transcription and cell-cycle progression, a hypomorphic cdk7 mutant suppressed apoptosis without impairing these other known functions. In this cdk7 mutant background, Hid failed to localize to the mitochondria and failed to bind to recombinant inhibitors of apoptosis (IAPs). These findings indicate that apoptosis is promoted by a newly identified function of CDK7, which couples the mitochondrial localization and IAP binding of Hid.
Collapse
Affiliation(s)
- Jun Morishita
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Min-Ji Kang
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Kevin Fidelin
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Hyung Don Ryoo
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA.
| |
Collapse
|
40
|
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
| |
Collapse
|
41
|
Ciurciu A, Duncalf L, Jonchere V, Lansdale N, Vasieva O, Glenday P, Rudenko A, Vissi E, Cobbe N, Alphey L, Bennett D. PNUTS/PP1 regulates RNAPII-mediated gene expression and is necessary for developmental growth. PLoS Genet 2013; 9:e1003885. [PMID: 24204300 PMCID: PMC3814315 DOI: 10.1371/journal.pgen.1003885] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 09/03/2013] [Indexed: 12/25/2022] Open
Abstract
In multicellular organisms, tight regulation of gene expression ensures appropriate tissue and organismal growth throughout development. Reversible phosphorylation of the RNA Polymerase II (RNAPII) C-terminal domain (CTD) is critical for the regulation of gene expression states, but how phosphorylation is actively modified in a developmental context remains poorly understood. Protein phosphatase 1 (PP1) is one of several enzymes that has been reported to dephosphorylate the RNAPII CTD. However, PP1's contribution to transcriptional regulation during animal development and the mechanisms by which its activity is targeted to RNAPII have not been fully elucidated. Here we show that the Drosophila orthologue of the PP1 Nuclear Targeting Subunit (dPNUTS) is essential for organismal development and is cell autonomously required for growth of developing tissues. The function of dPNUTS in tissue development depends on its binding to PP1, which we show is targeted by dPNUTS to RNAPII at many active sites of transcription on chromosomes. Loss of dPNUTS function or specific disruption of its ability to bind PP1 results in hyperphosphorylation of the RNAPII CTD in whole animal extracts and on chromosomes. Consistent with dPNUTS being a global transcriptional regulator, we find that loss of dPNUTS function affects the expression of the majority of genes in developing 1st instar larvae, including those that promote proliferative growth. Together, these findings shed light on the in vivo role of the PNUTS-PP1 holoenzyme and its contribution to the control of gene expression during early Drosophila development. During development, cells rely on appropriate patterns of gene expression to regulate metabolism in order to meet cellular demands and maintain rapid tissue growth. Conversely, dysregulation of gene expression is critical in various disease states, such as cancer, and during ageing. A key mechanism that is ubiquitously employed to control gene expression is reversible phosphorylation, a molecular switch that is used to regulate the activity of the transcriptional machinery. Here we identify an enzyme that binds to and regulates the phosphorylation state of RNA Polymerase II, a central component of the general transcription machinery. We also show that an essential role of this enzyme is to support normal patterns of gene expression that facilitate organismal growth. These findings are not only of relevance to the understanding of normal enzyme function but may also assist in the development of therapeutic strategies for the treatment of aberrant patterns of gene expression that occur during ageing and disease progression.
Collapse
Affiliation(s)
- Anita Ciurciu
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Louise Duncalf
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Vincent Jonchere
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Nick Lansdale
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Olga Vasieva
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Peter Glenday
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- Department of Zoology, Oxford University, Oxford, United Kingdom
| | - Andreii Rudenko
- Department of Zoology, Oxford University, Oxford, United Kingdom
| | - Emese Vissi
- Department of Zoology, Oxford University, Oxford, United Kingdom
| | - Neville Cobbe
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Luke Alphey
- Department of Zoology, Oxford University, Oxford, United Kingdom
| | - Daimark Bennett
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| |
Collapse
|
42
|
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
| |
Collapse
|
43
|
Jeronimo C, Bataille AR, Robert F. The Writers, Readers, and Functions of the RNA Polymerase II C-Terminal Domain Code. Chem Rev 2013; 113:8491-522. [DOI: 10.1021/cr4001397] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Célia Jeronimo
- Institut de recherches cliniques de Montréal, Montréal, Québec,
Canada H2W 1R7
| | - Alain R. Bataille
- Institut de recherches cliniques de Montréal, Montréal, Québec,
Canada H2W 1R7
| | - François Robert
- Institut de recherches cliniques de Montréal, Montréal, Québec,
Canada H2W 1R7
- Département
de Médecine,
Faculté de Médecine, Université de Montréal, Montréal, Québec,
Canada H3T 1J4
| |
Collapse
|
44
|
Abstract
Cyclin-dependent kinases (CDKs) play a central role in governing eukaryotic cell division. It is becoming clear that the transcription cycle of RNA polymerase II (RNAP II) is also regulated by CDKs; in metazoans, the cell cycle and transcriptional CDK networks even share an upstream activating kinase, which is itself a CDK. From recent chemical-genetic analyses we know that CDKs and their substrates control events both early in transcription (the transition from initiation to elongation) and late (3' end formation and transcription termination). Moreover, mutual dependence on CDK activity might couple the "beginning" and "end" of the cycle, to ensure the fidelity of mRNA maturation and the efficient recycling of RNAP II from sites of termination to the transcription start site (TSS). As is the case for CDKs involved in cell cycle regulation, different transcriptional CDKs act in defined sequence on multiple substrates. These phosphorylations are likely to influence gene expression by several mechanisms, including direct, allosteric effects on the transcription machinery, co-transcriptional recruitment of proteins needed for mRNA-capping, splicing and 3' end maturation, dependent on multisite phosphorylation of the RNAP II C-terminal domain (CTD) and, perhaps, direct regulation of RNA-processing or histone-modifying machinery. Here we review these recent advances, and preview the emerging challenges for transcription-cycle research.
Collapse
Affiliation(s)
- Miriam Sansó
- Department of Structural and Chemical Biology; Icahn School of Medicine at Mount Sinai; New York, NY USA
| | | |
Collapse
|
45
|
Bedez F, Linard B, Brochet X, Ripp R, Thompson JD, Moras D, Lecompte O, Poch O. Functional insights into the core-TFIIH from a comparative survey. Genomics 2012; 101:178-86. [PMID: 23147676 DOI: 10.1016/j.ygeno.2012.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/31/2012] [Accepted: 11/02/2012] [Indexed: 10/27/2022]
Abstract
TFIIH is a eukaryotic complex composed of two subcomplexes, the CAK (Cdk activating kinase) and the core-TFIIH. The core-TFIIH, composed of seven subunits (XPB, XPD, P62, P52, P44, P34, and P8), plays a crucial role in transcription and repair. Here, we performed an extended sequence analysis to establish the accurate phylogenetic distribution of the core-TFIIH in 63 eukaryotic organisms. In spite of the high conservation of the seven subunits at the sequence and genomic levels, the non-enzymatic P8, P34, P52 and P62 are absent from one or a few unicellular species. To gain insight into their respective roles, we undertook a comparative genomic analysis of the whole proteome to identify the gene sets sharing similar presence/absence patterns. While little information was inferred for P8 and P62, our studies confirm the known role of P52 in repair and suggest for the first time the implication of the core TFIIH in mRNA splicing via P34.
Collapse
Affiliation(s)
- Florence Bedez
- Laboratoire de Bioinformatique et Génomique Intégratives, Institut de Génétique et de Biologie Moléculaire et Cellulaire (CNRS, INSERM, UDS), BP163, 67404 Illkirch Cedex, France
| | | | | | | | | | | | | | | |
Collapse
|
46
|
Gaillard H, Aguilera A. Transcription coupled repair at the interface between transcription elongation and mRNP biogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:141-50. [PMID: 23046879 DOI: 10.1016/j.bbagrm.2012.09.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 09/19/2012] [Accepted: 09/22/2012] [Indexed: 01/13/2023]
Abstract
During transcription, the nascent pre-mRNA associates with mRNA-binding proteins and undergoes a series of processing steps, resulting in export competent mRNA ribonucleoprotein complexes (mRNPs) that are transported into the cytoplasm. Throughout transcription elongation, RNA polymerases frequently deal with a number of obstacles that need to be removed for transcription resumption. One important type of hindrance consists of helix-distorting DNA lesions. Transcription-coupled repair (TC-NER), a specific sub-pathway of nucleotide excision repair, ensures a fast repair of such transcription-blocking lesions. While the nucleotide excision repair reaction is fairly well understood, its regulation and the way it deals with DNA transcription remains largely unknown. In this review, we update our current understanding of the factors involved in TC-NER and discuss their functional interplay with the processes of transcription elongation and mRNP biogenesis. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
Collapse
|
47
|
Frey AG, Eide DJ. Zinc-responsive coactivator recruitment by the yeast Zap1 transcription factor. Microbiologyopen 2012; 1:105-14. [PMID: 22950018 PMCID: PMC3426420 DOI: 10.1002/mbo3.8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 12/19/2011] [Indexed: 11/11/2022] Open
Abstract
The zinc-responsive Zap1 transcription factor of Saccharomyces cerevisiae controls many genes involved in zinc homeostasis. Zap1 has two activation domains, AD1 and AD2, which are independently regulated by zinc. While AD1 can fully activate most Zap1 target genes, AD2 is active only on a subset of those genes. One hypothesis explaining this promoter specificity was that AD1 and AD2 recruit different coactivators. To address this question, we carried out a genetic screen to identify coactivator complexes that are required for Zap1-mediated activation. SWI/SNF, SAGA, and Mediator complexes were implicated as playing major roles in Zap1 activation. Consistent with this conclusion, we found that these three complexes are recruited to Zap1 target promoters in a zinc-responsive and Zap1-dependent manner. Coactivator recruitment was highly interdependent such that mutations disrupting SAGA impaired recruitment of SWI/SNF and vice versa. Optimal Mediator recruitment was dependent on both SAGA and SWI/SNF. A comparison of the coactivators recruited by AD1 and AD2 found no obvious differences suggesting that recruitment of different coactivators is not likely the mechanism of AD specificity. Rather, our results suggest that AD2 recruits coactivators less effectively than AD1 and is therefore only functional on some promoters.
Collapse
Affiliation(s)
- Avery G Frey
- Department of Nutritional Sciences, University of Wisconsin-Madison Madison, Wisconsin
| | | |
Collapse
|
48
|
Heidemann M, Hintermair C, Voß K, Eick D. Dynamic phosphorylation patterns of RNA polymerase II CTD during transcription. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1829:55-62. [PMID: 22982363 DOI: 10.1016/j.bbagrm.2012.08.013] [Citation(s) in RCA: 205] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 08/09/2012] [Accepted: 08/29/2012] [Indexed: 12/27/2022]
Abstract
The eukaryotic RNA polymerase II (RNAPII) catalyzes the transcription of all protein encoding genes and is also responsible for the generation of small regulatory RNAs. RNAPII has evolved a unique domain composed of heptapeptide repeats with the consensus sequence Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7 at the C-terminus (CTD) of its largest subunit (Rpb1). Dynamic phosphorylation patterns of serine residues in CTD during gene transcription coordinate the recruitment of factors to the elongating RNAPII and to the nascent transcript. Recent studies identified threonine 4 and tyrosine 1 as new CTD modifications and thereby expanded the "CTD code". In this review, we focus on CTD phosphorylation and its function in the RNAPII transcription cycle. We also discuss in detail the limitations of the phosphospecific CTD antibodies, which are used in all studies. This article is part of a Special Issue entitled: RNA Polymerase II Transcript Elongation.
Collapse
Affiliation(s)
- Martin Heidemann
- Department of Molecular Epigenetics, Center for Integrated Protein Science Munich, Munich, Germany
| | | | | | | |
Collapse
|
49
|
Enserink JM. Chemical genetics: budding yeast as a platform for drug discovery and mapping of genetic pathways. Molecules 2012; 17:9258-73. [PMID: 22858845 PMCID: PMC6268143 DOI: 10.3390/molecules17089258] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 07/18/2012] [Accepted: 07/23/2012] [Indexed: 01/18/2023] Open
Abstract
The budding yeast Saccharomyces cerevisiae is a widely used model organism, and yeast genetic methods are powerful tools for discovery of novel functions of genes. Recent advancements in chemical-genetics and chemical-genomics have opened new avenues for development of clinically relevant drug treatments. Systematic mapping of genetic networks by high-throughput chemical-genetic screens have given extensive insight in connections between genetic pathways. Here, I review some of the recent developments in chemical-genetic techniques in budding yeast.
Collapse
Affiliation(s)
- Jorrit M Enserink
- Department of Molecular Biology, Institute of Medical Microbiology and Centre for Molecular Biology and Neuroscience, Oslo University Hospital, Sognsvannsveien 20, NO-0027 Oslo, Norway.
| |
Collapse
|
50
|
Qiu H, Hu C, Gaur NA, Hinnebusch AG. Pol II CTD kinases Bur1 and Kin28 promote Spt5 CTR-independent recruitment of Paf1 complex. EMBO J 2012; 31:3494-505. [PMID: 22796944 DOI: 10.1038/emboj.2012.188] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 06/20/2012] [Indexed: 11/09/2022] Open
Abstract
Paf1 complex (Paf1C) is a transcription elongation factor whose recruitment is stimulated by Spt5 and the CDKs Kin28 and Bur1, which phosphorylate the Pol II C-terminal domain (CTD) on Serines 2, 5, and 7. Bur1 promotes Paf1C recruitment by phosphorylating C-terminal repeats (CTRs) in Spt5, and we show that Kin28 enhances Spt5 phosphorylation by promoting Bur1 recruitment. It was unclear, however, whether CTD phosphorylation by Kin28 or Bur1 also stimulates Paf1C recruitment. We find that Paf1C and its Cdc73 subunit bind diphosphorylated CTD repeats (pCTD) and phosphorylated Spt5 CTRs (pCTRs) in vitro, and that cdc73 mutations eliminating both activities reduce Paf1C recruitment in vivo. Phosphomimetic (acidic) substitutions in the Spt5 CTR sustain high-level Paf1C recruitment in otherwise wild-type cells, but not following inactivation of Bur1 or Kin28. Furthermore, inactivating the pCTD/pCTR-interaction domain (PCID) in Cdc73 decreases Paf1C-dependent histone methylation in cells containing non-phosphorylatable Spt5 CTRs. These results identify an Spt5 pCTR-independent pathway of Paf1C recruitment requiring Kin28, Bur1, and the Cdc73 PCID. We propose that pCTD repeats and Spt5 pCTRs provide separate interaction surfaces that cooperate to ensure high-level Paf1C recruitment.
Collapse
Affiliation(s)
- Hongfang Qiu
- Laboratory of Gene Regulation and Development, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | | | | | | |
Collapse
|