1
|
Feng Z, Liu S, Su M, Song C, Lin C, Zhao F, Li Y, Zeng X, Zhu Y, Hou Y, Ren C, Zhang H, Yi P, Ji Y, Wang C, Li H, Ma M, Luo L, Li L. TANGO6 regulates cell proliferation via COPI vesicle-mediated RPB2 nuclear entry. Nat Commun 2024; 15:2371. [PMID: 38490996 PMCID: PMC10943085 DOI: 10.1038/s41467-024-46720-y] [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: 11/02/2022] [Accepted: 03/01/2024] [Indexed: 03/18/2024] Open
Abstract
Coat protein complex I (COPI) vesicles mediate the retrograde transfer of cargo between Golgi cisternae and from the Golgi to the endoplasmic reticulum (ER). However, their roles in the cell cycle and proliferation are unclear. This study shows that TANGO6 associates with COPI vesicles via two transmembrane domains. The TANGO6 N- and C-terminal cytoplasmic fragments capture RNA polymerase II subunit B (RPB) 2 in the cis-Golgi during the G1 phase. COPI-docked TANGO6 carries RPB2 to the ER and then to the nucleus. Functional disruption of TANGO6 hinders the nuclear entry of RPB2, which accumulates in the cytoplasm, causing cell cycle arrest in the G1 phase. The conditional depletion or overexpression of TANGO6 in mouse hematopoietic stem cells results in compromised or expanded hematopoiesis. Our study results demonstrate that COPI vesicle-associated TANGO6 plays a role in the regulation of cell cycle progression by directing the nuclear transfer of RPB2, making it a potential target for promoting or arresting cell expansion.
Collapse
Affiliation(s)
- Zhi Feng
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China
| | - Shengnan Liu
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Ming Su
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China
| | - Chunyu Song
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Chenyu Lin
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Fangying Zhao
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Yang Li
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China
| | - Xianyan Zeng
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Yong Zhu
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Yu Hou
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Chunguang Ren
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Huan Zhang
- Institute of Life Sciences, Laboratory of Developmental Biology, Department of Cell Biology and Genetics, Chongqing Medical University, Chongqing, 400016, PR China
| | - Ping Yi
- Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Chongqing Medical University, Chongqing, 401120, PR China
| | - Yong Ji
- Key Laboratory of Cardiovascular and Cerebrovascular Medicine; Key Laboratory of Targeted Intervention of Cardiovascular Disease; Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing, 211166, PR China
- National Key Laboratory of Frigid Zone Cardiovascular Diseases (NKLFZCD), Harbin Medical University, Harbin, 150076, Heilongjiang, PR China
| | - Chao Wang
- MOE Key Laboratory for Membraneless Organelles & Cellular Dynamics, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei, 230027, PR China
| | - Hongtao Li
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Ming Ma
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China
| | - Lingfei Luo
- Institute of Developmental Biology and Regenerative Medicine, Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Southwest University, Chongqing, 400715, PR China.
| | - Li Li
- Research center of Stem cells and Ageing, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing, 400714, PR China.
| |
Collapse
|
2
|
Garrido-Godino AI, Cuevas-Bermúdez A, Gutiérrez-Santiago F, Mota-Trujillo MDC, Navarro F. The Association of Rpb4 with RNA Polymerase II Depends on CTD Ser5P Phosphatase Rtr1 and Influences mRNA Decay in Saccharomyces cerevisiae. Int J Mol Sci 2022; 23:ijms23042002. [PMID: 35216121 PMCID: PMC8875030 DOI: 10.3390/ijms23042002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/03/2022] [Accepted: 02/07/2022] [Indexed: 02/04/2023] Open
Abstract
Rtr1 is an RNA polymerase II (RNA pol II) CTD-phosphatase that influences gene expression during the transition from transcription initiation to elongation and during transcription termination. Rtr1 interacts with the RNA pol II and this interaction depends on the phosphorylation state of the CTD of Rpb1, which may influence dissociation of the heterodimer Rpb4/7 during transcription. In addition, Rtr1 was proposed as an RNA pol II import factor in RNA pol II biogenesis and participates in mRNA decay by autoregulating the turnover of its own mRNA. Our work shows that Rtr1 acts in RNA pol II assembly by mediating the Rpb4/7 association with the rest of the enzyme. RTR1 deletion alters RNA pol II assembly and increases the amount of RNA pol II associated with the chromatin that lacks Rpb4, decreasing Rpb4-mRNA imprinting and, consequently, increasing mRNA stability. Thus, Rtr1 interplays RNA pol II biogenesis and mRNA decay regulation. Our data also indicate that Rtr1 mediates mRNA decay regulation more broadly than previously proposed by cooperating with Rpb4. Interestingly, our data include new layers in the mechanisms of gene regulation and in the crosstalk between mRNA synthesis and decay by demonstrating how the association of Rpb4/7 to the RNA pol II influences mRNA decay.
Collapse
Affiliation(s)
- Ana I. Garrido-Godino
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Abel Cuevas-Bermúdez
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Francisco Gutiérrez-Santiago
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Maria del Carmen Mota-Trujillo
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
| | - Francisco Navarro
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain; (A.I.G.-G.); (A.C.-B.); (F.G.-S.); (M.d.C.M.-T.)
- Centro de Estudios Avanzados en Aceite de Oliva y Olivar, Universidad de Jaén, Paraje de las Lagunillas, s/n, E-23071 Jaén, Spain
- Correspondence: ; Tel.: +34-953-212-771; Fax: +34-953-211-875
| |
Collapse
|
3
|
Garrido-Godino AI, Gutiérrez-Santiago F, Navarro F. Biogenesis of RNA Polymerases in Yeast. Front Mol Biosci 2021; 8:669300. [PMID: 34026841 PMCID: PMC8136413 DOI: 10.3389/fmolb.2021.669300] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/31/2021] [Indexed: 01/25/2023] Open
Abstract
Eukaryotic RNA polymerases (RNA pols) transcriptional processes have been extensively investigated, and the structural analysis of eukaryotic RNA pols has been explored. However, the global assembly and biogenesis of these heteromultimeric complexes have been narrowly studied. Despite nuclear transcription being carried out by three RNA polymerases in eukaryotes (five in plants) with specificity in the synthesis of different RNA types, the biogenesis process has been proposed to be similar, at least for RNA pol II, to that of bacteria, which contains only one RNA pol. The formation of three different interacting subassembly complexes to conform the complete enzyme in the cytoplasm, prior to its nuclear import, has been assumed. In Saccharomyces cerevisiae, recent studies have examined in depth the biogenesis of RNA polymerases by characterizing some elements involved in the assembly of these multisubunit complexes, some of which are conserved in humans. This study reviews the latest studies governing the mechanisms and proteins described as being involved in the biogenesis of RNA polymerases in yeast.
Collapse
Affiliation(s)
- Ana I Garrido-Godino
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Jaén, Spain
| | | | - Francisco Navarro
- Departamento de Biología Experimental-Genética, Universidad de Jaén, Jaén, Spain.,Centro de Estudios Avanzados en Aceite de Oliva y Olivar, Universidad de Jaén, Jaén, Spain
| |
Collapse
|
4
|
Yu W, Min D, Lin F, Zheng S, Tang L, He A, Hu H, Shen Z. SKA1 induces de novo MTX-resistance in osteosarcoma through inhibiting FPGS transcription. FEBS J 2019; 286:2399-2414. [PMID: 30851225 DOI: 10.1111/febs.14808] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/22/2018] [Accepted: 03/07/2019] [Indexed: 12/30/2022]
Abstract
De novo methotrexate (MTX)-resistance, whose underlying mechanism remains largely unknown, usually leads to very poor prognosis in patients with osteosarcoma (OS). In this study, we established the de novo MTX-resistant OS cell line SF-86 and identified the candidate gene spindle and kinetochore associated complex subunit 1 (SKA1) as potentially related to de novo MTX-resistance. Analysis of a cohort of 95 OS patients demonstrated that SKA1 overexpression significantly correlated with de novo MTX-resistance and poor 5-year survival. Mechanistically, SKA1 overexpression lead to a downregulation of folylpoly-γ-glutamate synthetase (FPGS), a key enzyme that converts MTX into its active form, MTX-PG. We further demonstrated that SKA1 interacts with DNA-directed RNA polymerase II subunit RPB3. ChIP analysis revealed that RPB3 binds the promoter region of the FPGS gene and triggers FPGS transcription upon MTX treatment in SW1353, a MTX-sensitive OS cell line lacking endogenous SKA1 expression. On the contrary, this process is blocked in SF-86 cells due to the formation of an inhibitory SKA1-RPB3 complex. Furthermore, downregulation of SKA1 levels restores MTX sensitivity in SF-86. Collectively, our study has established the de novo MTX-resistant cell line SF-86 and identified SKA1 as a novel regulator of FPGS, playing a key role in the development of de novo MTX-resistance in OS.
Collapse
Affiliation(s)
- Wenxi Yu
- Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| | - Daliu Min
- East Campus, Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| | - Feng Lin
- Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| | - Shuier Zheng
- Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| | - Lina Tang
- Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| | - Aina He
- Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| | - Haiyan Hu
- Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| | - Zan Shen
- Department of Oncology, Affiliated 6th People's Hospital, Shanghai Jiaotong University, China
| |
Collapse
|
5
|
Gpn2 and Rba50 Directly Participate in the Assembly of the Rpb3 Subcomplex in the Biogenesis of RNA Polymerase II. Mol Cell Biol 2018; 38:MCB.00091-18. [PMID: 29661922 DOI: 10.1128/mcb.00091-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 04/08/2018] [Indexed: 01/12/2023] Open
Abstract
RNA polymerase II (RNAPII) is one of the central enzymes in cell growth and organizational development. It is a large macromolecular complex consisting of 12 subunits. Relative to the clear definition of RNAPII structure and biological function, the molecular mechanism of how RNAPII is assembled is poorly understood, and thus the key assembly factors acting for the assembly of RNAPII remain elusive. In this study, we identified two factors, Gpn2 and Rba50, that directly participate in the assembly of RNAPII. Gpn2 and Rba50 were demonstrated to interact with Rpb12 and Rpb3, respectively. An interaction between Gpn2 and Rba50 was also demonstrated. When Gpn2 and Rba50 are functionally defective, the assembly of the Rpb3 subcomplex is disrupted, leading to defects in the assembly of RNAPII. Based on these results, we conclude that Gpn2 and Rba50 directly participate in the assembly of the Rpb3 subcomplex and subsequently the biogenesis of RNAPII.
Collapse
|
6
|
Cloutier P, Poitras C, Durand M, Hekmat O, Fiola-Masson É, Bouchard A, Faubert D, Chabot B, Coulombe B. R2TP/Prefoldin-like component RUVBL1/RUVBL2 directly interacts with ZNHIT2 to regulate assembly of U5 small nuclear ribonucleoprotein. Nat Commun 2017; 8:15615. [PMID: 28561026 PMCID: PMC5460035 DOI: 10.1038/ncomms15615] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 04/12/2017] [Indexed: 01/11/2023] Open
Abstract
The R2TP/Prefoldin-like (R2TP/PFDL) complex has emerged as a cochaperone complex involved in the assembly of a number of critical protein complexes including snoRNPs, nuclear RNA polymerases and PIKK-containing complexes. Here we report on the use of multiple target affinity purification coupled to mass spectrometry to identify two additional complexes that interact with R2TP/PFDL: the TSC1–TSC2 complex and the U5 small nuclear ribonucleoprotein (snRNP). The interaction between R2TP/PFDL and the U5 snRNP is mostly mediated by the previously uncharacterized factor ZNHIT2. A more general function for the zinc-finger HIT domain in binding RUVBL2 is exposed. Disruption of ZNHIT2 and RUVBL2 expression impacts the protein composition of the U5 snRNP suggesting a function for these proteins in promoting the assembly of the ribonucleoprotein. A possible implication of R2TP/PFDL as a major effector of stress-, energy- and nutrient-sensing pathways that regulate anabolic processes through the regulation of its chaperoning activity is discussed. The R2TP/Prefoldin-like cochaperone complex is involved in the assembly of a number of protein complexes. Here the authors provide evidence that RUVBL1/RUVBL2, subunits of that cochaperone complex, directly interact with ZNHIT2 to regulate assembly of U5 small ribonucleoprotein.
Collapse
Affiliation(s)
- Philippe Cloutier
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Christian Poitras
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Mathieu Durand
- Laboratory of Functional Genomics, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1E 4K8
| | - Omid Hekmat
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Émilie Fiola-Masson
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Annie Bouchard
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Denis Faubert
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7
| | - Benoit Chabot
- Laboratory of Functional Genomics, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1E 4K8.,Département de Microbiologie et d'Infectiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1E 4K8
| | - Benoit Coulombe
- Translational Proteomics Laboratory, Institut de Recherches Cliniques de Montréal (IRCM), Montreal, Quebec, Canada H2W 1R7.,Département de Biochimie, Université de Montréal, Montreal, Quebec, Canada H3T 1J4
| |
Collapse
|
7
|
Gómez-Navarro N, Peiró-Chova L, Estruch F. Iwr1 facilitates RNA polymerase II dynamics during transcription elongation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2017; 1860:803-811. [PMID: 28258010 DOI: 10.1016/j.bbagrm.2017.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 02/16/2017] [Accepted: 02/27/2017] [Indexed: 11/16/2022]
Abstract
Iwr1 is an RNA polymerase II (RNPII) interacting protein that directs nuclear import of the enzyme which has been previously assembled in the cytoplasm. Here we present genetic and molecular evidence that links Iwr1 with transcription. Our results indicate that Iwr1 interacts with RNPII during elongation and is involved in the disassembly of the enzyme from chromatin. This function is especially important in resolving problems posed by damage-arrested RNPII, as shown by the sensitivity of iwr1 mutants to genotoxic drugs and the Iwr1's genetic interactions with RNPII degradation pathway mutants. Moreover, absence of Iwr1 causes genome instability that is enhanced by defects in the DNA repair machinery.
Collapse
Affiliation(s)
- Natalia Gómez-Navarro
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain
| | - Lorena Peiró-Chova
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain
| | - Francisco Estruch
- Departamento de Bioquímica y Biología Molecular, Universidad de Valencia, Burjassot, Valencia 46100, Spain.
| |
Collapse
|
8
|
Human Gpn1 purified from bacteria binds guanine nucleotides and hydrolyzes GTP as a protein dimer stabilized by its C-terminal tail. Protein Expr Purif 2017; 132:85-96. [PMID: 28153773 DOI: 10.1016/j.pep.2017.01.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 12/23/2016] [Accepted: 01/25/2017] [Indexed: 12/20/2022]
Abstract
The essential GTPase Gpn1 mediates RNA polymerase II nuclear targeting and controls microtubule dynamics in yeast and human cells by molecular mechanisms still under investigation. Here, we purified human HisGpn1 expressed as a recombinant protein in bacteria E. coli BL-21 (DE3). Affinity purified HisGpn1 eluted from a size exclusion column as a protein dimer, a state conserved after removing the hexa-histidine tail and confirmed by separating HisGpn1 in native gels, and in dynamic light scattering experiments. Human HisGpn1 purity was higher than 95%, molecularly monodisperse and could be concentrated to more than 10 mg/mL without aggregating. Circular dichroism spectra showed that human HisGpn1 was properly folded and displayed a secondary structure rich in alpha helices. HisGpn1 effectively bound GDP and the non-hydrolyzable GTP analogue GMPPCP, and hydrolyzed GTP. We next tested the importance of the C-terminal tail, present in eukaryotic Gpn1 but not in the ancestral archaeal Gpn protein, on HisGpn1 dimer formation. C-terminal deleted human HisGpn1 (HisGpn1ΔC) was also purified as a protein dimer, indicating that the N-terminal GTPase domain contains the interaction surface needed for dimer formation. In contrast to HisGpn1, however, HisGpn1ΔC dimer spontaneously dissociated into monomers. In conclusion, we have developed a method to purify properly folded and functionally active human HisGpn1 from bacteria, and showed that the C-terminal tail, universally conserved in all eukaryotic Gpn1 orthologues, stabilizes the GTPase domain-mediated Gpn1 protein dimer. The availability of recombinant human Gpn1 will open new research avenues to unveil the molecular and pharmacological properties of this essential GTPase.
Collapse
|
9
|
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.
Collapse
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.
| |
Collapse
|
10
|
Vernekar DV, Bhargava P. Yeast Bud27 modulates the biogenesis of Rpc128 and Rpc160 subunits and the assembly of RNA polymerase III. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1849:1340-53. [PMID: 26423792 DOI: 10.1016/j.bbagrm.2015.09.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 09/23/2015] [Accepted: 09/25/2015] [Indexed: 01/22/2023]
Abstract
Yeast Bud27, an unconventional prefoldin is reported to affect the expression of nutrient-responsive genes, translation initiation and assembly of the multi-subunit eukaryotic RNA polymerases (pols), at a late step. We found that Bud27 associates with pol III in active as well as repressed states. Pol III transcription and occupancy at the target genes reduce with the deletion of BUD27. It promotes the interaction of pol III with the chromatin remodeler RSC found on most of the pol III targets, and with the heat shock protein Ssa4, which helps in nuclear import of the assembled pol III. Under nutrient-starvation, Ssa4-pol III interaction increases, while pol III remains inside the nucleus. Bud27 but not Ssa4 is required for RSC-pol III interaction, which reduces under nutrient-starvation. In the bud27Δ cells, total protein level of the largest pol III subunit Rpc160 but not of Rpc128, Rpc34 and Rpc53 subunits is reduced. This is accompanied by lower transcription of RPC128 gene and lower RPC160 translation due to reduced association of mRNA with the ribosomes. The resultant alteration in the normal cellular ratio of the two largest subunits of pol III core leads to reduced association of other pol III subunits and hampers the normal assembly of pol III at an early step in the cytoplasm. Our results show that Bud27 is required in multiple activities responsible for pol III biogenesis and activity.
Collapse
Affiliation(s)
- Dipti Vinayak Vernekar
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India
| | - Purnima Bhargava
- Centre for Cellular and Molecular Biology (Council of Scientific and Industrial Research), Uppal Road, Hyderabad 500007, India.
| |
Collapse
|
11
|
Rbs1, a new protein implicated in RNA polymerase III biogenesis in yeast Saccharomyces cerevisiae. Mol Cell Biol 2015; 35:1169-81. [PMID: 25605335 DOI: 10.1128/mcb.01230-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Little is known about the RNA polymerase III (Pol III) complex assembly and its transport to the nucleus. We demonstrate that a missense cold-sensitive mutation, rpc128-1007, in the sequence encoding the C-terminal part of the second largest Pol III subunit, C128, affects the assembly and stability of the enzyme. The cellular levels and nuclear concentration of selected Pol III subunits were decreased in rpc128-1007 cells, and the association between Pol III subunits as evaluated by coimmunoprecipitation was also reduced. To identify the proteins involved in Pol III assembly, we performed a genetic screen for suppressors of the rpc128-1007 mutation and selected the Rbs1 gene, whose overexpression enhanced de novo tRNA transcription in rpc128-1007 cells, which correlated with increased stability, nuclear concentration, and interaction of Pol III subunits. The rpc128-1007 rbs1Δ double mutant shows a synthetic growth defect, indicating that rpc128-1007 and rbs1Δ function in parallel ways to negatively regulate Pol III assembly. Rbs1 physically interacts with a subset of Pol III subunits, AC19, AC40, and ABC27/Rpb5. Additionally, Rbs1 interacts with the Crm1 exportin and shuttles between the cytoplasm and nucleus. We postulate that Rbs1 binds to the Pol III complex or subcomplex and facilitates its translocation to the nucleus.
Collapse
|