1
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Wang K, Zhang T, Li X, Zhang X, Li R, Pan B, Deng J. Identification of hub genes and potential therapeutic mechanisms related to HPV positive head and neck squamous carcinoma based on full transcriptomic detection and ceRNA network construction. Gene 2024; 910:148321. [PMID: 38428621 DOI: 10.1016/j.gene.2024.148321] [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: 11/16/2023] [Revised: 02/21/2024] [Accepted: 02/26/2024] [Indexed: 03/03/2024]
Abstract
Infection with human papillomavirus (HPV) is a major risk factor for head and neck squamous cell carcinoma (HNSCC). The objective of this study is to investigate the gene expression profiles and signaling pathways that are specific to HPV-positive HNSCC (HPV+ HNSCC). Moreover, a competing endogenous RNA (ceRNA) network analysis was utilized to identify the core gene of HPV+ HNSCC and potential targeted therapeutic drugs. Transcriptome sequencing analysis identified 3,253 coding RNAs and 3,903 non-coding RNAs (ncRNAs) that exhibited preferentially expressed in HPV+ HNSCC. Four key signaling pathways were selected through pathway enrichment analysis. By combining ceRNA network and protein-protein interaction (PPI) network topology analysis, RNA Polymerase II Associated Protein 2 (RPAP2), which also exhibited high expression in HPV+ HNSCC based on the TCGA database, was identified as the hub gene. Gene set enrichment analysis (GSEA) results revealed RPAP2's involvement in various signaling pathways, encompassing basal transcription factors, ubiquitin-mediated proteolysis, adherens junction, other glycan degradation, ATP-binding cassette (ABC) transporters, and oglycan biosynthesis. Five potential small molecule targeted drugs (enzastaurin, brequinar, talinolol, phenylbutazone, and afuresertib) were identified using the cMAP database, with enzastaurin showing the highest affinity for RPAP2. Cellular functional experiments confirmed the inhibitory effect of enzastaurin on cell viability of HPV+ HNSCC and RPAP2 expression levels. Additionally, enzastaurin treatment suppressed the expression levels of the top-ranked long non-coding RNA (lncRNA), circular RNA (circRNA), and microRNA (miRNA) in the ceRNA network. This study based on the ceRNA network provides valuable insights into the molecular mechanisms and potential therapeutic strategies for HPV+ HNSCC, and provide theoretical basis for the exploration of HPV+ HNSCC biomarkers and the development of targeted drugs.
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Affiliation(s)
- Kunpeng Wang
- The School and Hospital of Stomatology, Tianjin Medical University, Tianjin 300070, China
| | - Tingting Zhang
- The School and Hospital of Stomatology, Tianjin Medical University, Tianjin 300070, China
| | - Xia Li
- The School and Hospital of Stomatology, Tianjin Medical University, Tianjin 300070, China
| | - Xinran Zhang
- The School and Hospital of Stomatology, Tianjin Medical University, Tianjin 300070, China
| | - Rui Li
- Department of Biochemistry and Molecular Biology, Key Laboratory of Breast Cancer Prevention and Therapy, Ministry of Education, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Tianjin 300060, China.
| | - Boyu Pan
- Tianjin Medical University Cancer Institute & Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Tianjin 300060, China.
| | - Jiayin Deng
- The School and Hospital of Stomatology, Tianjin Medical University, Tianjin 300070, China.
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2
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Ma L, Wang L, Gao M, Zhang X, Zhao X, Xie D, Zhang J, Wang Z, Hou L, Zeng F. Rtr1 is required for Rpb1-Rpb2 assembly of RNAPII and prevents their cytoplasmic clump formation. FASEB J 2022; 36:e22585. [PMID: 36190433 DOI: 10.1096/fj.202200698rr] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/03/2022] [Accepted: 09/20/2022] [Indexed: 11/11/2022]
Abstract
RNA polymerase II (RNAPII) is an essential machinery for catalyzing mRNA synthesis and controlling cell fate in eukaryotes. Although the structure and function of RNAPII have been relatively defined, the molecular mechanism of its assembly process is not clear. The identification and functional analysis of assembly factors will provide new understanding to transcription regulation. In this study, we identify that RTR1, a known transcription regulator, is a new multicopy genetic suppressor of mutants of assembly factors Gpn3, Gpn2, and Rba50. We demonstrate that Rtr1 is directly required to assemble the two largest subunits of RNAPII by coordinating with Gpn3 and Npa3. Deletion of RTR1 leads to cytoplasmic clumping of RNAPII subunit and multiple copies of RTR1 can inhibit the formation of cytoplasmic clump of RNAPII subunit in gpn3-9 mutant, indicating a new layer function of Rtr1 in checking proper assembly of RNAPII. In addition, we find that disrupted activity of Rtr1 phosphatase does not trigger the formation of cytoplasmic clump of RNAPII subunit in a catalytically inactive mutant of RTR1. Based on these results, we conclude that Rtr1 cooperates with Gpn3 and Npa3 to assemble RNAPII core.
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Affiliation(s)
- Lujie Ma
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, China.,College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Le Wang
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Mengdi Gao
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Xinjie Zhang
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Xiangdong Zhao
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Debao Xie
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Jing Zhang
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Zhen Wang
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, China.,College of Science & Technology, Hebei Agricultural University, Cangzhou, China
| | - Lifeng Hou
- College of Life Sciences, Hebei Agricultural University, Baoding, China
| | - Fanli Zeng
- State Key Laboratory of North China Crop Improvement and Regulation, Baoding, China.,College of Life Sciences, Hebei Agricultural University, Baoding, China
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3
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Song A, Chen FX. The pleiotropic roles of SPT5 in transcription. Transcription 2022; 13:53-69. [PMID: 35876486 PMCID: PMC9467590 DOI: 10.1080/21541264.2022.2103366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Initially discovered by genetic screens in budding yeast, SPT5 and its partner SPT4 form a stable complex known as DSIF in metazoa, which plays pleiotropic roles in multiple steps of transcription. SPT5 is the most conserved transcription elongation factor, being found in all three domains of life; however, its structure has evolved to include new domains and associated posttranslational modifications. These gained features have expanded transcriptional functions of SPT5, likely to meet the demand for increasingly complex regulation of transcription in higher organisms. This review discusses the pleiotropic roles of SPT5 in transcription, including RNA polymerase II (Pol II) stabilization, enhancer activation, Pol II pausing and its release, elongation, and termination, with a focus on the most recent progress of SPT5 functions in regulating metazoan transcription.
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Affiliation(s)
- Aixia Song
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, Province 200032, China
| | - Fei Xavier Chen
- Fudan University Shanghai Cancer Center, Institutes of Biomedical Sciences, State Key Laboratory of Genetic Engineering and Shanghai Key Laboratory of Medical Epigenetics, Shanghai Medical College of Fudan University, Shanghai, Province 200032, China
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4
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RPAP2 regulates a transcription initiation checkpoint by inhibiting assembly of pre-initiation complex. Cell Rep 2022; 39:110732. [PMID: 35476980 DOI: 10.1016/j.celrep.2022.110732] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 12/31/2021] [Accepted: 04/02/2022] [Indexed: 11/21/2022] Open
Abstract
RNA polymerase II (Pol II)-mediated transcription in metazoans requires precise regulation. RNA Pol II-associated protein 2 (RPAP2) was previously identified to transport Pol II from cytoplasm to nucleus and dephosphorylates Pol II C-terminal domain (CTD). Here, we show that RPAP2 binds hypo-/hyper-phosphorylated Pol II with undetectable phosphatase activity. The structure of RPAP2-Pol II shows mutually exclusive assembly of RPAP2-Pol II and pre-initiation complex (PIC) due to three steric clashes. RPAP2 prevents and disrupts Pol II-TFIIF interaction and impairs in vitro transcription initiation, suggesting a function in inhibiting PIC assembly. Loss of RPAP2 in cells leads to global accumulation of TFIIF and Pol II at promoters, indicating a critical role of RPAP2 in inhibiting PIC assembly independent of its putative phosphatase activity. Our study indicates that RPAP2 functions as a gatekeeper to inhibit PIC assembly and transcription initiation and suggests a transcription checkpoint.
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5
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Kim HS, Jeon Y, Jang YO, Lee H, Shin Y, Lee CW. Mammalian Ssu72 phosphatase preferentially considers tissue-specific actively transcribed gene expression by regulating RNA Pol II transcription. Theranostics 2022; 12:186-206. [PMID: 34987641 PMCID: PMC8690912 DOI: 10.7150/thno.62274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 10/26/2021] [Indexed: 11/12/2022] Open
Abstract
Reversible phosphorylation of the C-terminal domain (CTD) of RNA polymerase II (Pol II) is essential for gene expression control. How altering the phosphorylation of the CTD contributes to gene expression in mammalian systems remains poorly understood. Methods: Primary mouse embryonic fibroblasts, hepatocytes, and embryonic stem cells were isolated from conditional Ssu72f/f mice. To knockout the mouse Ssu72 gene, we infected the cells with adenoviruses of incorporated luciferase and Cre recombinase, respectively. RNA sequencing, ChIP sequencing, ChIP assay, immunoblot analyses, qRT-PCR assay, and immunostaining were performed to gain insights into the functional mechanisms of Ssu72 loss in Pol II dynamics. Results: Using primary cells isolated from Ssu72 conditional knockout and transgenic mice, we found that mammalian Ssu72-mediated transcriptional elongation rather than polyadenylation or RNA processing contributed to the transcriptional regulation of various genes. Depletion of Ssu72 resulted in aberrant Pol II pausing and elongation defects. Reduced transcriptional elongation efficiency tended to preferentially affect expression levels of actively transcribed genes in a tissue-specific manner. Furthermore, Ssu72 CTD phosphatase seemed to regulate the phosphorylation levels of CTD Ser2 and Thr4 through accurate modulation of P-TEFb activity and recruitment. Conclusions: Our findings demonstrate that mammalian Ssu72 contributes to the transcription of tissue-specific actively transcribed gene expression by regulating reciprocal phosphorylation of Pol II CTD.
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6
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Fianu I, Dienemann C, Aibara S, Schilbach S, Cramer P. Cryo-EM structure of mammalian RNA polymerase II in complex with human RPAP2. Commun Biol 2021; 4:606. [PMID: 34021257 PMCID: PMC8140126 DOI: 10.1038/s42003-021-02088-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/08/2021] [Indexed: 11/09/2022] Open
Abstract
Nuclear import of RNA polymerase II (Pol II) involves the conserved factor RPAP2. Here we report the cryo-electron microscopy (cryo-EM) structure of mammalian Pol II in complex with human RPAP2 at 2.8 Å resolution. The structure shows that RPAP2 binds between the jaw domains of the polymerase subunits RPB1 and RPB5. RPAP2 is incompatible with binding of downstream DNA during transcription and is displaced upon formation of a transcription pre-initiation complex.
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Affiliation(s)
- Isaac Fianu
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christian Dienemann
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Shintaro Aibara
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Sandra Schilbach
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
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7
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Cossa G, Parua PK, Eilers M, Fisher RP. Protein phosphatases in the RNAPII transcription cycle: erasers, sculptors, gatekeepers, and potential drug targets. Genes Dev 2021; 35:658-676. [PMID: 33888562 PMCID: PMC8091971 DOI: 10.1101/gad.348315.121] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In this review, Cossa et al. discuss the current knowledge and outstanding questions about phosphatases in the context of the RNAPII transcription cycle. The transcription cycle of RNA polymerase II (RNAPII) is governed at multiple points by opposing actions of cyclin-dependent kinases (CDKs) and protein phosphatases, in a process with similarities to the cell division cycle. While important roles of the kinases have been established, phosphatases have emerged more slowly as key players in transcription, and large gaps remain in understanding of their precise functions and targets. Much of the earlier work focused on the roles and regulation of sui generis and often atypical phosphatases—FCP1, Rtr1/RPAP2, and SSU72—with seemingly dedicated functions in RNAPII transcription. Decisive roles in the transcription cycle have now been uncovered for members of the major phosphoprotein phosphatase (PPP) family, including PP1, PP2A, and PP4—abundant enzymes with pleiotropic roles in cellular signaling pathways. These phosphatases appear to act principally at the transitions between transcription cycle phases, ensuring fine control of elongation and termination. Much is still unknown, however, about the division of labor among the PPP family members, and their possible regulation by or of the transcriptional kinases. CDKs active in transcription have recently drawn attention as potential therapeutic targets in cancer and other diseases, raising the prospect that the phosphatases might also present opportunities for new drug development. Here we review the current knowledge and outstanding questions about phosphatases in the context of the RNAPII transcription cycle.
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Affiliation(s)
- Giacomo Cossa
- Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Pabitra K Parua
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Martin Eilers
- Department of Biochemistry and Molecular Biology, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Robert P Fisher
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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8
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Offley SR, Schmidt MC. Protein phosphatases of Saccharomyces cerevisiae. Curr Genet 2018; 65:41-55. [PMID: 30225534 DOI: 10.1007/s00294-018-0884-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/27/2018] [Accepted: 09/08/2018] [Indexed: 10/28/2022]
Abstract
The phosphorylation status of a protein is highly regulated and is determined by the opposing activities of protein kinases and protein phosphatases within the cell. While much is known about the protein kinases found in Saccharomyces cerevisiae, the protein phosphatases are much less characterized. Of the 127 protein kinases in yeast, over 90% are in the same evolutionary lineage. In contrast, protein phosphatases are fewer in number (only 43 have been identified in yeast) and comprise multiple, distinct evolutionary lineages. Here we review the protein phosphatase families of yeast with regard to structure, catalytic mechanism, regulation, and signal transduction participation.
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Affiliation(s)
- Sarah R Offley
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA, 15219, USA
| | - Martin C Schmidt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, 450 Technology Drive, Pittsburgh, PA, 15219, USA.
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9
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Yurko NM, Manley JL. The RNA polymerase II CTD "orphan" residues: Emerging insights into the functions of Tyr-1, Thr-4, and Ser-7. Transcription 2017; 9:30-40. [PMID: 28771071 DOI: 10.1080/21541264.2017.1338176] [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: 12/26/2022] Open
Abstract
The C-terminal domain (CTD) of the RNA polymerase II largest subunit consists of a unique repeated heptad sequence of the consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. An important function of the CTD is to couple transcription with RNA processing reactions that occur during the initiation, elongation, and termination phases of transcription. During this transcription cycle, the CTD is subject to extensive modification, primarily phosphorylation, on its non-proline residues. Reversible phosphorylation of Ser2 and Ser5 is well known to play important and general functions during transcription in all eukaryotes. More recent studies have enhanced our understanding of Tyr1, Thr4, and Ser7, and what have been previously characterized as unknown or specialized functions for these residues has changed to a more fine-detailed map of transcriptional regulation that highlights similarities as well as significant differences between organisms. Here, we review recent findings on the function and modification of these three residues, which further illustrate the importance of the CTD in precisely modulating gene expression.
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Affiliation(s)
- Nathan M Yurko
- a Department of Biological Sciences , Columbia University , New York , NY , USA
| | - James L Manley
- a Department of Biological Sciences , Columbia University , New York , NY , USA
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10
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Muñoz A, Mangano S, González-García MP, Contreras R, Sauer M, De Rybel B, Weijers D, Sánchez-Serrano JJ, Sanmartín M, Rojo E. RIMA-Dependent Nuclear Accumulation of IYO Triggers Auxin-Irreversible Cell Differentiation in Arabidopsis. THE PLANT CELL 2017; 29:575-588. [PMID: 28223441 PMCID: PMC5385956 DOI: 10.1105/tpc.16.00791] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Revised: 12/28/2016] [Accepted: 02/14/2017] [Indexed: 05/09/2023]
Abstract
The transcriptional regulator MINIYO (IYO) is essential and rate-limiting for initiating cell differentiation in Arabidopsis thaliana Moreover, IYO moves from the cytosol into the nucleus in cells at the meristem periphery, possibly triggering their differentiation. However, the genetic mechanisms controlling IYO nuclear accumulation were unknown, and the evidence that increased nuclear IYO levels trigger differentiation remained correlative. Searching for IYO interactors, we identified RPAP2 IYO Mate (RIMA), a homolog of yeast and human proteins linked to nuclear import of selective cargo. Knockdown of RIMA causes delayed onset of cell differentiation, phenocopying the effects of IYO knockdown at the transcriptomic and developmental levels. Moreover, differentiation is completely blocked when IYO and RIMA activities are simultaneously reduced and is synergistically accelerated when IYO and RIMA are concurrently overexpressed, confirming their functional interaction. Indeed, RIMA knockdown reduces the nuclear levels of IYO and prevents its prodifferentiation activity, supporting the conclusion that RIMA-dependent nuclear IYO accumulation triggers cell differentiation in Arabidopsis. Importantly, by analyzing the effect of the IYO/RIMA pathway on xylem pole pericycle cells, we provide compelling evidence reinforcing the view that the capacity for de novo organogenesis and regeneration from mature plant tissues can reside in stem cell reservoirs.
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Affiliation(s)
- Alfonso Muñoz
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Silvina Mangano
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | | | - Ramón Contreras
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Michael Sauer
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Bert De Rybel
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University, 6703 HA Wageningen, The Netherlands
| | | | - Maite Sanmartín
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
| | - Enrique Rojo
- Centro Nacional de Biotecnología-CSIC, Cantoblanco, E-28049 Madrid, Spain
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11
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Abstract
Transcription and splicing are fundamental steps in gene expression. These processes have been studied intensively over the past four decades, and very recent findings are challenging some of the formerly established ideas. In particular, splicing was shown to occur much faster than previously thought, with the first spliced products observed as soon as splice junctions emerge from RNA polymerase II (Pol II). Splicing was also found coupled to a specific phosphorylation pattern of Pol II carboxyl-terminal domain (CTD), suggesting a new layer of complexity in the CTD code. Moreover, phosphorylation of the CTD may be scarcer than expected, and other post-translational modifications of the CTD are emerging with unanticipated roles in gene expression regulation.
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Affiliation(s)
- Noélia Custódio
- a Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa , Lisboa , Portugal
| | - Maria Carmo-Fonseca
- a Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa , Lisboa , Portugal
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12
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Jeronimo C, Collin P, Robert F. The RNA Polymerase II CTD: The Increasing Complexity of a Low-Complexity Protein Domain. J Mol Biol 2016; 428:2607-2622. [DOI: 10.1016/j.jmb.2016.02.006] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 01/27/2016] [Accepted: 02/02/2016] [Indexed: 01/18/2023]
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13
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Irani S, Yogesha SD, Mayfield J, Zhang M, Zhang Y, Matthews WL, Nie G, Prescott NA, Zhang YJ. Structure of Saccharomyces cerevisiae Rtr1 reveals an active site for an atypical phosphatase. Sci Signal 2016; 9:ra24. [PMID: 26933063 DOI: 10.1126/scisignal.aad4805] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Changes in the phosphorylation status of the carboxyl-terminal domain (CTD) of RNA polymerase II (RNAPII) correlate with the process of eukaryotic transcription. The yeast protein regulator of transcription 1 (Rtr1) and the human homolog RNAPII-associated protein 2 (RPAP2) may function as CTD phosphatases; however, crystal structures of Kluyveromyces lactis Rtr1 lack a consensus active site. We identified a phosphoryl transfer domain in Saccharomyces cerevisiae Rtr1 by obtaining and characterizing a 2.6 Å resolution crystal structure. We identified a putative substrate-binding pocket in a deep groove between the zinc finger domain and a pair of helices that contained a trapped sulfate ion. Because sulfate mimics the chemistry of a phosphate group, this structural data suggested that this groove represents the phosphoryl transfer active site. Mutagenesis of the residues lining this groove disrupted catalytic activity of the enzyme assayed in vitro with a fluorescent chemical substrate, and expression of the mutated Rtr1 failed to rescue growth of yeast lacking Rtr1. Characterization of the phosphatase activity of RPAP2 and a mutant of the conserved putative catalytic site in the same chemical assay indicated a conserved reaction mechanism. Our data indicated that the structure of the phosphoryl transfer domain and reaction mechanism for the phosphoryl transfer activity of Rtr1 is distinct from those of other phosphatase families.
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Affiliation(s)
- Seema Irani
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - S D Yogesha
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Joshua Mayfield
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Mengmeng Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Yong Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Wendy L Matthews
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Grace Nie
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Nicholas A Prescott
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA.,Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA
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14
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Lamas-Maceiras M, Singh BN, Hampsey M, Freire-Picos MA. Promoter-Terminator Gene Loops Affect Alternative 3'-End Processing in Yeast. J Biol Chem 2016; 291:8960-8. [PMID: 26929407 DOI: 10.1074/jbc.m115.687491] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Indexed: 11/06/2022] Open
Abstract
Many eukaryotic genes undergo alternative 3'-end poly(A)-site selection producing transcript isoforms with 3'-UTRs of different lengths and post-transcriptional fates. Gene loops are dynamic structures that juxtapose the 3'-ends of genes with their promoters. Several functions have been attributed to looping, including memory of recent transcriptional activity and polarity of transcription initiation. In this study, we investigated the relationship between gene loops and alternative poly(A)-site. Using the KlCYC1 gene of the yeast Kluyveromyces lactis, which includes a single promoter and two poly(A) sites separated by 394 nucleotides, we demonstrate in two yeast species the formation of alternative gene loops (L1 and L2) that juxtapose the KlCYC1 promoter with either proximal or distal 3'-end processing sites, resulting in the synthesis of short and long forms of KlCYC1 mRNA. Furthermore, synthesis of short and long mRNAs and formation of the L1 and L2 loops are growth phase-dependent. Chromatin immunoprecipitation experiments revealed that the Ssu72 RNA polymerase II carboxyl-terminal domain phosphatase, a critical determinant of looping, peaks in early log phase at the proximal poly(A) site, but as growth phase advances, it extends to the distal site. These results define a cause-and-effect relationship between gene loops and alternative poly(A) site selection that responds to different physiological signals manifested by RNA polymerase II carboxyl-terminal domain phosphorylation status.
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Affiliation(s)
- Mónica Lamas-Maceiras
- From the Departamento de Biología Celular e Molecular, Facultad de Ciencias, Universidade da Coruña, Campus de A Coruña, Rúa da Fraga 10, 15008 A Coruña, Spain and
| | - Badri Nath Singh
- the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - Michael Hampsey
- the Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - María A Freire-Picos
- From the Departamento de Biología Celular e Molecular, Facultad de Ciencias, Universidade da Coruña, Campus de A Coruña, Rúa da Fraga 10, 15008 A Coruña, Spain and
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15
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Mayfield JE, Burkholder NT, Zhang YJ. Dephosphorylating eukaryotic RNA polymerase II. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2016; 1864:372-87. [PMID: 26779935 DOI: 10.1016/j.bbapap.2016.01.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/11/2016] [Accepted: 01/14/2016] [Indexed: 12/20/2022]
Abstract
The phosphorylation state of the C-terminal domain of RNA polymerase II is required for the temporal and spatial recruitment of various factors that mediate transcription and RNA processing throughout the transcriptional cycle. Therefore, changes in CTD phosphorylation by site-specific kinases/phosphatases are critical for the accurate transmission of information during transcription. Unlike kinases, CTD phosphatases have been traditionally neglected as they are thought to act as passive negative regulators that remove all phosphate marks at the conclusion of transcription. This over-simplified view has been disputed in recent years and new data assert the active and regulatory role phosphatases play in transcription. We now know that CTD phosphatases ensure the proper transition between different stages of transcription, balance the distribution of phosphorylation for accurate termination and re-initiation, and prevent inappropriate expression of certain genes. In this review, we focus on the specific roles of CTD phosphatases in regulating transcription. In particular, we emphasize how specificity and timing of dephosphorylation are achieved for these phosphatases and consider the various regulatory factors that affect these dynamics.
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Affiliation(s)
- Joshua E Mayfield
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Nathaniel T Burkholder
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
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16
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Gómez-Navarro N, Estruch F. Different pathways for the nuclear import of yeast RNA polymerase II. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1354-62. [PMID: 26455955 DOI: 10.1016/j.bbagrm.2015.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 09/17/2015] [Accepted: 10/05/2015] [Indexed: 11/30/2022]
Abstract
Recent studies suggest that RNA polymerase II (Pol II) has to be fully assembled before being imported into the nucleus, while other reports indicate a distinct mechanism to import large and small subunits. In yeast, Iwr1 binds to the holoenzyme assembled in the cytoplasm and directs its nuclear entry. However, as IWR1 is not an essential gene, Iwr1-independent pathway(s) for the nuclear import of Pol II must exist. In this paper, we investigate the transport into the nucleus of several large and small Pol II subunits in the mutants of genes involved in Pol II biogenesis. We also analyse subcellular localization in the presence of drugs that can potentially affect Pol II nuclear import. Our results show differences in the cellular distribution between large and small subunits when Pol II biogenesis was impaired. Our data suggest that, in addition to the fully assembled holoenzyme, Pol II subunits can be imported to the nucleus, either independently or as partial assemblies, through different pathways, including passive diffusion for the small subunits.
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Affiliation(s)
- Natalia Gómez-Navarro
- Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universitat de València, Burjassot 46100, Spain; E.R.I. Biotecmed, Universitat de València, Burjassot, Spain
| | - Francisco Estruch
- Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universitat de València, Burjassot 46100, Spain; E.R.I. Biotecmed, Universitat de València, Burjassot, Spain.
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17
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Baillat D, Wagner EJ. Integrator: surprisingly diverse functions in gene expression. Trends Biochem Sci 2015; 40:257-64. [PMID: 25882383 DOI: 10.1016/j.tibs.2015.03.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 03/07/2015] [Accepted: 03/09/2015] [Indexed: 01/06/2023]
Abstract
The discovery of the metazoan-specific Integrator (INT) complex represented a breakthrough in our understanding of noncoding U-rich small nuclear RNA (UsnRNA) maturation and has triggered a reevaluation of their biosynthesis mechanism. In the decade since, significant progress has been made in understanding the details of its recruitment, specificity, and assembly. While some discrepancies remain on how it interacts with the C-terminal domain (CTD) of the RNA polymerase II (RNAPII) and the details of its recruitment to UsnRNA genes, preliminary models have emerged. Recent provocative studies now implicate INT in the regulation of protein-coding gene transcription initiation and RNAPII pause-release, thereby broadening the scope of INT functions in gene expression regulation. We discuss the implications of these findings while putting them into the context of what is understood about INT function at UsnRNA genes.
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Affiliation(s)
- David Baillat
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, TX 77030, USA.
| | - Eric J Wagner
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, TX 77030, USA; The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.
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18
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Smith-Kinnaman WR, Berna MJ, Hunter GO, True JD, Hsu P, Cabello GI, Fox MJ, Varani G, Mosley AL. The interactome of the atypical phosphatase Rtr1 in Saccharomyces cerevisiae. MOLECULAR BIOSYSTEMS 2015; 10:1730-41. [PMID: 24671508 DOI: 10.1039/c4mb00109e] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The phosphatase Rtr1 has been implicated in dephosphorylation of the RNA Polymerase II (RNAPII) C-terminal domain (CTD) during transcription elongation and in regulation of nuclear import of RNAPII. Although it has been shown that Rtr1 interacts with RNAPII in yeast and humans, the specific mechanisms that underlie Rtr1 recruitment to RNAPII have not been elucidated. To address this, we have performed an in-depth proteomic analysis of Rtr1 interacting proteins in yeast. Our studies revealed that hyperphosphorylated RNAPII is the primary interacting partner for Rtr1. To extend these findings, we performed quantitative proteomic analyses of Rtr1 interactions in yeast strains deleted for CTK1, the gene encoding the catalytic subunit of the CTD kinase I (CTDK-I) complex. Interestingly, we found that the interaction between Rtr1 and RNAPII is decreased in ctk1Δ strains. We hypothesize that serine-2 CTD phosphorylation is required for Rtr1 recruitment to RNAPII during transcription elongation.
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Affiliation(s)
- Whitney R Smith-Kinnaman
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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19
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Allepuz-Fuster P, Martínez-Fernández V, Garrido-Godino AI, Alonso-Aguado S, Hanes SD, Navarro F, Calvo O. Rpb4/7 facilitates RNA polymerase II CTD dephosphorylation. Nucleic Acids Res 2014; 42:13674-88. [PMID: 25416796 PMCID: PMC4267648 DOI: 10.1093/nar/gku1227] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 11/04/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022] Open
Abstract
The Rpb4 and Rpb7 subunits of eukaryotic RNA polymerase II (RNAPII) participate in a variety of processes from transcription, DNA repair, mRNA export and decay, to translation regulation and stress response. However, their mechanism(s) of action remains unclear. Here, we show that the Rpb4/7 heterodimer in Saccharomyces cerevisiae plays a key role in controlling phosphorylation of the carboxy terminal domain (CTD) of the Rpb1 subunit of RNAPII. Proper phosphorylation of the CTD is critical for the synthesis and processing of RNAPII transcripts. Deletion of RPB4, and mutations that disrupt the integrity of Rpb4/7 or its recruitment to the RNAPII complex, increased phosphorylation of Ser2, Ser5, Ser7 and Thr4 within the CTD. RPB4 interacted genetically with genes encoding CTD phosphatases (SSU72, FCP1), CTD kinases (KIN28, CTK1, SRB10) and a prolyl isomerase that targets the CTD (ESS1). We show that Rpb4 is important for Ssu72 and Fcp1 phosphatases association, recruitment and/or accessibility to the CTD, and that this correlates strongly with Ser5P and Ser2P levels, respectively. Our data also suggest that Fcp1 is the Thr4P phosphatase in yeast. Based on these and other results, we suggest a model in which Rpb4/7 helps recruit and potentially stimulate the activity of CTD-modifying enzymes, a role that is central to RNAPII function.
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Affiliation(s)
- Paula Allepuz-Fuster
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, Salamanca 37007, Spain
| | - Verónica Martínez-Fernández
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén 23071, Spain
| | - Ana I. Garrido-Godino
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén 23071, Spain
| | - Sergio Alonso-Aguado
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, Salamanca 37007, Spain
| | - Steven D. Hanes
- Department of Biochemistry and Molecular Biology, Upstate Medical University, Syracuse, NY 13210, USA
| | - Francisco Navarro
- Departamento de Biología Experimental, Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén 23071, Spain
| | - Olga Calvo
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca, Salamanca 37007, Spain
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20
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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.
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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
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21
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Hsu PL, Yang F, Smith-Kinnaman W, Yang W, Song JE, Mosley AL, Varani G. Rtr1 is a dual specificity phosphatase that dephosphorylates Tyr1 and Ser5 on the RNA polymerase II CTD. J Mol Biol 2014; 426:2970-81. [PMID: 24951832 PMCID: PMC4119023 DOI: 10.1016/j.jmb.2014.06.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2014] [Revised: 06/11/2014] [Accepted: 06/12/2014] [Indexed: 01/07/2023]
Abstract
The phosphorylation state of heptapeptide repeats within the C-terminal domain (CTD) of the largest subunit of RNA polymerase II (PolII) controls the transcription cycle and is maintained by the competing action of kinases and phosphatases. Rtr1 was recently proposed to be the enzyme responsible for the transition of PolII into the elongation and termination phases of transcription by removing the phosphate marker on serine 5, but this attribution was questioned by the apparent lack of enzymatic activity. Here we demonstrate that Rtr1 is a phosphatase of new structure that is auto-inhibited by its own C-terminus. The enzymatic activity of the protein in vitro is functionally important in vivo as well: a single amino acid mutation that reduces activity leads to the same phenotype in vivo as deletion of the protein-coding gene from yeast. Surprisingly, Rtr1 dephosphorylates not only serine 5 on the CTD but also the newly described anti-termination tyrosine 1 marker, supporting the hypothesis that Rtr1 and its homologs promote the transition from transcription to termination.
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Affiliation(s)
- Peter L. Hsu
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Fan Yang
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Whitney Smith-Kinnaman
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Wen Yang
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Jae-Eun Song
- Department of Chemistry, University of Washington, Seattle, Washington, USA
| | - Amber L. Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Gabriele Varani
- Department of Chemistry, University of Washington, Seattle, Washington, USA,Corresponding author. , telephone (206) 543-7113
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22
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Ni Z, Xu C, Guo X, Hunter GO, Kuznetsova OV, Tempel W, Marcon E, Zhong G, Guo H, Kuo WHW, Li J, Young P, Olsen JB, Wan C, Loppnau P, El Bakkouri M, Senisterra GA, He H, Huang H, Sidhu SS, Emili A, Murphy S, Mosley AL, Arrowsmith CH, Min J, Greenblatt JF. RPRD1A and RPRD1B are human RNA polymerase II C-terminal domain scaffolds for Ser5 dephosphorylation. Nat Struct Mol Biol 2014; 21:686-695. [PMID: 24997600 PMCID: PMC4124035 DOI: 10.1038/nsmb.2853] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 06/02/2014] [Indexed: 01/16/2023]
Abstract
The RNA polymerase II (RNAPII) C-terminal domain (CTD) heptapeptide repeats (1-YSPTSPS-7) undergo dynamic phosphorylation and dephosphorylation during the transcription cycle to recruit factors that regulate transcription, RNA processing and chromatin modification. We show here that RPRD1A and RPRD1B form homodimers and heterodimers through their coiled-coil domains and interact preferentially via CTD-interaction domains (CIDs) with RNAPII CTD repeats phosphorylated at S2 and S7. Crystal structures of the RPRD1A, RPRD1B and RPRD2 CIDs, alone and in complex with RNAPII CTD phosphoisoforms, elucidate the molecular basis of CTD recognition. In an example of cross-talk between different CTD modifications, our data also indicate that RPRD1A and RPRD1B associate directly with RPAP2 phosphatase and, by interacting with CTD repeats where phospho-S2 and/or phospho-S7 bracket a phospho-S5 residue, serve as CTD scaffolds to coordinate the dephosphorylation of phospho-S5 by RPAP2.
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Affiliation(s)
- Zuyao Ni
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Chao Xu
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Xinghua Guo
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gerald O Hunter
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Olga V Kuznetsova
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Wolfram Tempel
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Edyta Marcon
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Guoqing Zhong
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Hongbo Guo
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Wei-Hung William Kuo
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Joyce Li
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Peter Young
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Jonathan B Olsen
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Cuihong Wan
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Peter Loppnau
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Majida El Bakkouri
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | | | - Hao He
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
| | - Haiming Huang
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Sachdev S Sidhu
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Emili
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Shona Murphy
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Amber L Mosley
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Cheryl H Arrowsmith
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Medical Biophysics, University of Toronto, Ontario Cancer Institute, Campbell Family Cancer Research Institute, Toronto, Ontario, Canada
| | - Jinrong Min
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Jack F Greenblatt
- Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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23
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Function and control of RNA polymerase II C-terminal domain phosphorylation in vertebrate transcription and RNA processing. Mol Cell Biol 2014; 34:2488-98. [PMID: 24752900 DOI: 10.1128/mcb.00181-14] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The C-terminal domain of the RNA polymerase II largest subunit (the Rpb1 CTD) is composed of tandem heptad repeats of the consensus sequence Y(1)S(2)P(3)T(4)S(5)P(6)S(7). We reported previously that Thr 4 is phosphorylated and functions in histone mRNA 3'-end formation in chicken DT40 cells. Here, we have extended our studies on Thr 4 and to other CTD mutations by using these cells. We found that an Rpb1 derivative containing only the N-terminal half of the CTD, as well as a similar derivative containing all-consensus repeats (26r), conferred full viability, while the C-terminal half, with more-divergent repeats, did not, reflecting a strong and specific defect in snRNA 3'-end formation. Mutation in 26r of all Ser 2 (S2A) or Ser 5 (S5A) residues resulted in lethality, while Ser 7 (S7A) mutants were fully viable. While S2A and S5A cells displayed defects in transcription and RNA processing, S7A cells behaved identically to 26r cells in all respects. Finally, we found that Thr 4 was phosphorylated by cyclin-dependent kinase 9 in cells and dephosphorylated both in vitro and in vivo by the phosphatase Fcp1.
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24
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Cross-talk of phosphorylation and prolyl isomerization of the C-terminal domain of RNA Polymerase II. Molecules 2014; 19:1481-511. [PMID: 24473209 PMCID: PMC4350670 DOI: 10.3390/molecules19021481] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 01/06/2014] [Accepted: 01/21/2014] [Indexed: 12/04/2022] Open
Abstract
Post-translational modifications of the heptad repeat sequences in the C-terminal domain (CTD) of RNA polymerase II (Pol II) are well recognized for their roles in coordinating transcription with other nuclear processes that impinge upon transcription by the Pol II machinery; and this is primarily achieved through CTD interactions with the various nuclear factors. The identification of novel modifications on new regulatory sites of the CTD suggests that, instead of an independent action for all modifications on CTD, a combinatorial effect is in operation. In this review we focus on two well-characterized modifications of the CTD, namely serine phosphorylation and prolyl isomerization, and discuss the complex interplay between the enzymes modifying their respective regulatory sites. We summarize the current understanding of how the prolyl isomerization state of the CTD dictates the specificity of writers (CTD kinases), erasers (CTD phosphatases) and readers (CTD binding proteins) and how that correlates to transcription status. Subtle changes in prolyl isomerization states cannot be detected at the primary sequence level, we describe the methods that have been utilized to investigate this mode of regulation. Finally, a general model of how prolyl isomerization regulates the phosphorylation state of CTD, and therefore transcription-coupled processes, is proposed.
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25
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Affiliation(s)
- Jiannan Guo
- Biochemistry Department, University of Iowa , Iowa City, Iowa 52242, United States
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26
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Corden JL. RNA polymerase II C-terminal domain: Tethering transcription to transcript and template. Chem Rev 2013; 113:8423-55. [PMID: 24040939 PMCID: PMC3988834 DOI: 10.1021/cr400158h] [Citation(s) in RCA: 127] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Jeffry L Corden
- Department of Molecular Biology and Genetics, The Johns Hopkins University School of Medicine , 725 North Wolfe Street, Baltimore Maryland 21205, United States
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27
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Hajheidari M, Koncz C, Eick D. Emerging roles for RNA polymerase II CTD in Arabidopsis. TRENDS IN PLANT SCIENCE 2013; 18:633-43. [PMID: 23910452 DOI: 10.1016/j.tplants.2013.07.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 06/12/2013] [Accepted: 07/01/2013] [Indexed: 05/20/2023]
Abstract
Post-translational modifications of the carboxy-terminal domain of the largest subunit of RNA polymerase II (RNAPII CTD) provide recognition marks to coordinate recruitment of numerous nuclear factors controlling transcription, cotranscriptional RNA processing, chromatin remodeling, and RNA export. Compared with the progress in yeast and mammals, deciphering the regulatory roles of position-specific combinatorial CTD modifications, the so-called CTD code, is still at an early stage in plants. In this review, we discuss some of the recent advances in understanding of the molecular mechanisms controlling the deposition and recognition of RNAPII CTD marks in plants during the transcriptional cycle and highlight some intriguing differences between regulatory components characterized in yeast, mammals, and plants.
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Affiliation(s)
- Mohsen Hajheidari
- Department of Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, D-50829 Cologne, Germany.
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28
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Pons T, Paramonov I, Boullosa C, Ibáñez K, Rojas AM, Valencia A. A common structural scaffold in CTD phosphatases that supports distinct catalytic mechanisms. Proteins 2013; 82:103-18. [PMID: 23900790 DOI: 10.1002/prot.24376] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/28/2013] [Accepted: 07/12/2013] [Indexed: 01/01/2023]
Abstract
The phosphorylation and dephosphorylation of the carboxyl-terminal domain (CTD) of the largest RNA polymerase II (RNAPII) subunit is a critical regulatory checkpoint for transcription and mRNA processing. This CTD is unique to eukaryotic organisms and it contains multiple tandem-repeats with the consensus sequence Tyr(1) -Ser(2) -Pro(3) -Thr(4) -Ser(5) -Pro(6) -Ser(7) . Traditionally, CTD phosphatases that use metal-ion-independent (cysteine-based) and metal-ion-assisted (aspartate-based) catalytic mechanisms have been considered to belong to two independent groups. However, using structural comparisons we have identified a common structural scaffold in these two groups of CTD phosphatases. This common scaffold accommodates different catalytic processes with the same substrate specificity, in this case phospho-serine/threonine residues flanked by prolines. Furthermore, this scaffold provides a structural connection between two groups of protein tyrosine phosphatases (PTPs): Cys-based (classes I, II, and III) and Asp-based (class IV) PTPs. Redundancy in catalytic mechanisms is not infrequent and may arise in specific biological settings. To better understand the activity of the CTD phosphatases, we combined our structural analyses with data on CTD phosphatase expression in different human and mouse tissues. The results suggest that aspartate- and cysteine-based CTD-dephosphorylation acts in concert during cellular stress, when high levels of reactive oxygen species can inhibit the nucleophilic function of the catalytic cysteine, as occurs in mental and neurodegenerative disorders like schizophrenia, Alzheimer's and Parkinson's diseases. Moreover, these findings have significant implications for the study of the RNAPII-CTD dephosphorylation in eukaryotes.
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Affiliation(s)
- Tirso Pons
- Structural Biology and BioComputing Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
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29
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Affiliation(s)
- Dirk Eick
- Department of Molecular Epigenetics, Helmholtz Center Munich and Center for Integrated Protein Science Munich (CIPSM), Marchioninistrasse 25, 81377 Munich,
Germany
| | - Matthias Geyer
- Center of Advanced European Studies and Research, Group Physical Biochemistry,
Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
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30
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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
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31
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Aitken S, Alexander RD, Beggs JD. A rule-based kinetic model of RNA polymerase II C-terminal domain phosphorylation. J R Soc Interface 2013; 10:20130438. [PMID: 23804443 PMCID: PMC3730697 DOI: 10.1098/rsif.2013.0438] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The complexity of many RNA processing pathways is such that a conventional systems modelling approach is inadequate to represent all the molecular species involved. We demonstrate that rule-based modelling permits a detailed model of a complex RNA signalling pathway to be defined. Phosphorylation of the RNA polymerase II (RNAPII) C-terminal domain (CTD; a flexible tail-like extension of the largest subunit) couples pre-messenger RNA capping, splicing and 3' end maturation to transcriptional elongation and termination, and plays a central role in integrating these processes. The phosphorylation states of the serine residues of many heptapeptide repeats of the CTD alter along the coding region of genes as a function of distance from the promoter. From a mechanistic perspective, both the changes in phosphorylation and the location at which they take place on the genes are a function of the time spent by RNAPII in elongation as this interval provides the opportunity for the kinases and phosphatases to interact with the CTD. On this basis, we synthesize the available data to create a kinetic model of the action of the known kinases and phosphatases to resolve the phosphorylation pathways and their kinetics.
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Affiliation(s)
- Stuart Aitken
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh EH4 2XU, UK.
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32
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Peart N, Sataluri A, Baillat D, Wagner EJ. Non-mRNA 3' end formation: how the other half lives. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:491-506. [PMID: 23754627 DOI: 10.1002/wrna.1174] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/25/2013] [Accepted: 04/26/2013] [Indexed: 12/27/2022]
Abstract
The release of nascent RNA from transcribing RNA polymerase complexes is required for all further functions carried out by RNA molecules. The elements and processing machinery involved in 3' end formation therefore represent key determinants in the biogenesis and accumulation of cellular RNA. While these factors have been well-characterized for messenger RNA, recent work has elucidated analogous pathways for the 3' end formation of other important cellular RNA. Here, we discuss four specific cases of non-mRNA 3' end formation-metazoan small nuclear RNA, Saccharomyces cerevisiae small nuclear RNA, Schizosaccharomyces pombe telomerase RNA, and the mammalian MALAT1 large noncoding RNA-as models of alternative mechanisms to generate RNA 3' ends. Comparison of these disparate processing pathways reveals an emerging theme of evolutionary ingenuity. In some instances, evidence for the creation of a dedicated processing complex exists; while in others, components are utilized from the existing RNA processing machinery and modified to custom fit the unique needs of the RNA substrate. Regardless of the details of how non-mRNA 3' ends are formed, the lengths to which biological systems will go to release nascent transcripts from their DNA templates are fundamental for cell survival.
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Affiliation(s)
- Natoya Peart
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, TX, USA
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Forget D, Lacombe AA, Cloutier P, Lavallée-Adam M, Blanchette M, Coulombe B. Nuclear import of RNA polymerase II is coupled with nucleocytoplasmic shuttling of the RNA polymerase II-associated protein 2. Nucleic Acids Res 2013; 41:6881-91. [PMID: 23723243 PMCID: PMC3737550 DOI: 10.1093/nar/gkt455] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The RNA polymerase II (RNAP II)-associated protein (RPAP) 2 has been discovered through its association with various subunits of RNAP II in affinity purification coupled with mass spectrometry experiments. Here, we show that RPAP2 is a mainly cytoplasmic protein that shuttles between the cytoplasm and the nucleus. RPAP2 shuttling is tightly coupled with nuclear import of RNAP II, as RPAP2 silencing provokes abnormal accumulation of RNAP II in the cytoplasmic space. Most notably, RPAP4/GPN1 silencing provokes the retention of RPAP2 in the nucleus. Our results support a model in which RPAP2 enters the nucleus in association with RNAP II and returns to the cytoplasm in association with the GTPase GPN1/RPAP4. Although binding of RNAP II to RPAP2 is mediated by an N-terminal domain (amino acids 1–170) that contains a nuclear retention domain, and binding of RPAP4/GPN1 to RPAP2 occurs through a C-terminal domain (amino acids 156–612) that has a dominant cytoplasmic localization domain. In conjunction with previously published data, our results have important implications, as they indicate that RPAP2 controls gene expression by two distinct mechanisms, one that targets RNAP II activity during transcription and the other that controls availability of RNAP II in the nucleus.
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Affiliation(s)
- Diane Forget
- Institut de Recherches Cliniques de Montréal (IRCM), Montréal, Québec, Canada H2W 1R7, McGill Centre for Bioinformatics and School of Computer Science, McGill University, Montréal, Québec, Canada H3A 2B4
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Hsin JP, Manley JL. The RNA polymerase II CTD coordinates transcription and RNA processing. Genes Dev 2012; 26:2119-37. [PMID: 23028141 DOI: 10.1101/gad.200303.112] [Citation(s) in RCA: 461] [Impact Index Per Article: 38.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The C-terminal domain (CTD) of the RNA polymerase II largest subunit consists of multiple heptad repeats (consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7), varying in number from 26 in yeast to 52 in vertebrates. The CTD functions to help couple transcription and processing of the nascent RNA and also plays roles in transcription elongation and termination. The CTD is subject to extensive post-translational modification, most notably phosphorylation, during the transcription cycle, which modulates its activities in the above processes. Therefore, understanding the nature of CTD modifications, including how they function and how they are regulated, is essential to understanding the mechanisms that control gene expression. While the significance of phosphorylation of Ser2 and Ser5 residues has been studied and appreciated for some time, several additional modifications have more recently been added to the CTD repertoire, and insight into their function has begun to emerge. Here, we review findings regarding modification and function of the CTD, highlighting the important role this unique domain plays in coordinating gene activity.
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Affiliation(s)
- Jing-Ping Hsin
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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Chen J, Ezzeddine N, Waltenspiel B, Albrecht TR, Warren WD, Marzluff WF, Wagner EJ. An RNAi screen identifies additional members of the Drosophila Integrator complex and a requirement for cyclin C/Cdk8 in snRNA 3'-end formation. RNA (NEW YORK, N.Y.) 2012; 18:2148-2156. [PMID: 23097424 PMCID: PMC3504667 DOI: 10.1261/rna.035725.112] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Accepted: 09/17/2012] [Indexed: 06/01/2023]
Abstract
Formation of the 3' end of RNA polymerase II-transcribed snRNAs requires a poorly understood group of proteins called the Integrator complex. Here we used a fluorescence-based read-through reporter that expresses GFP in response to snRNA misprocessing and performed a genome-wide RNAi screen in Drosophila S2 cells to identify novel factors required for snRNA 3'-end formation. In addition to the known Integrator complex members, we identified Asunder and CG4785 as additional Integrator subunits. Functional and biochemical experiments revealed that Asunder and CG4785 are additional core members of the Integrator complex. We also identified a conserved requirement in both fly and human snRNA 3'-end processing for cyclin C and Cdk8 that is distinct from their function in the Mediator Cdk8 module. Moreover, we observed biochemical association between Integrator proteins and cyclin C/Cdk8, and that overexpression of a kinase-dead Cdk8 causes snRNA misprocessing. These data functionally define the Drosophila Integrator complex and demonstrate an additional function for cyclin C/Cdk8 unrelated to its function in Mediator.
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Affiliation(s)
- Jiandong Chen
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, Texas 77030, USA
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, USA
| | - Nader Ezzeddine
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, Texas 77030, USA
| | - Bernhard Waltenspiel
- Comparative Genomics Centre, School of Pharmacy and Molecular Sciences, James Cook University, Townsville QLD 4811, Queensland, Australia
| | - Todd R. Albrecht
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, Texas 77030, USA
| | - William D. Warren
- Comparative Genomics Centre, School of Pharmacy and Molecular Sciences, James Cook University, Townsville QLD 4811, Queensland, Australia
| | - William F. Marzluff
- Department of Biochemistry and Biophysics, Program in Molecular Biology and Biotechnology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Eric J. Wagner
- Department of Biochemistry and Molecular Biology, The University of Texas Medical School at Houston, Houston, Texas 77030, USA
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030, USA
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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.
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Affiliation(s)
- Martin Heidemann
- Department of Molecular Epigenetics, Center for Integrated Protein Science Munich, Munich, Germany
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