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Masnovo C, Paleiov Z, Dovrat D, Baxter LK, Movafaghi S, Aharoni A, Mirkin SM. Stabilization of expandable DNA repeats by the replication factor Mcm10 promotes cell viability. Nat Commun 2024; 15:10532. [PMID: 39627228 PMCID: PMC11615337 DOI: 10.1038/s41467-024-54977-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 11/22/2024] [Indexed: 12/06/2024] Open
Abstract
Trinucleotide repeats, including Friedreich's ataxia (GAA)n repeats, become pathogenic upon expansions during DNA replication and repair. Here, we show that deficiency of the essential replisome component Mcm10 dramatically elevates (GAA)n repeat instability in a budding yeast model by loss of proper CMG helicase interaction. Supporting this conclusion, live-cell microscopy experiments reveal increased replication fork stalling at the repeat in mcm10-1 cells. Unexpectedly, the viability of strains containing a single (GAA)100 repeat at an essential chromosomal location strongly depends on Mcm10 function and cellular RPA levels. This coincides with Rad9 checkpoint activation, which promotes cell viability, but initiates repeat expansions via DNA synthesis by polymerase δ. When repair is inefficient, such as in the case of RPA depletion, breakage of under-replicated repetitive DNA can occur during G2/M, leading to loss of essential genes and cell death. We hypothesize that the CMG-Mcm10 interaction promotes replication through hard-to-replicate regions, assuring genome stability and cell survival.
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Affiliation(s)
- Chiara Masnovo
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Zohar Paleiov
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, 8410501, Israel
| | - Daniel Dovrat
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, 8410501, Israel
| | - Laurel K Baxter
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Sofia Movafaghi
- Department of Biology, Tufts University, Medford, MA, 02155, USA
| | - Amir Aharoni
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, 8410501, Israel
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA, 02155, USA.
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2
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Krawczyk M, Halas A, Sledziewska-Gojska E. A novel role for Mms2 in the control of spontaneous mutagenesis and Pol3 abundance. DNA Repair (Amst) 2023; 125:103484. [PMID: 36934633 DOI: 10.1016/j.dnarep.2023.103484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/27/2023] [Accepted: 03/09/2023] [Indexed: 03/14/2023]
Abstract
Mms2 is a ubiquitin E2-variant protein with a very well-documented function in the tolerance pathway that protects both human and yeast cells from the lethal and mutagenic effects of DNA damage. Interestingly, a high expression level of human MMS2 is associated with poor survival prognosis in different cancer diseases. Here we have analyzed the physiological effects of Mms2 overproduction in yeast cells. We show that an increased level of this protein causes a spontaneous mutator effect independent of Ubc13, a cognate partner of Mms2 in the PCNA-polyubiquitinating complex responsible for the template switch. Instead, this new promutagenic role of Mms2 requires Ubc4 (E2) and two ubiquitin ligases of HECT and RING families, Rsp5 and Not4, respectively. We have established that the promutagenic activity of Mms2 is dependent on the activities of error-prone DNA polymerase ζ and Rev1. Additionally, it requires the ubiquitination of K164 in PCNA which facilitates recruitment of these translesion polymerases to the replication complex. Importantly, we have established also that the cellular abundance of Mms2 influences the cellular level of Pol3, the catalytic subunit of replicative DNA polymerase δ. Lack of Mms2 increases the Pol3 abundance, whereas in response to Mms2 overproduction the Pol3 level decreases. We hypothesize that increased levels of spontaneous mutagenesis may result from the Mms2-induced reduction in Pol3 accumulation leading to increased participation of error-prone polymerase ζ in the replication complex.
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Affiliation(s)
- Michal Krawczyk
- Laboratory of Mutagenesis and DNA Damage Tolerance, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Agnieszka Halas
- Laboratory of Mutagenesis and DNA Damage Tolerance, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland
| | - Ewa Sledziewska-Gojska
- Laboratory of Mutagenesis and DNA Damage Tolerance, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
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3
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Palermo V, Stirpe M, Bianchi MM, Rinaldi T, Cirigliano A, Ragnini-Wilson A, Falcone C, Mazzoni C. The C-terminal region of yeast ubiquitin-protein ligase Not4 mediates its cellular localization and stress response. FEMS Microbiol Lett 2021; 368:6335481. [PMID: 34338747 PMCID: PMC8370887 DOI: 10.1093/femsle/fnab097] [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: 04/03/2021] [Accepted: 07/29/2021] [Indexed: 11/24/2022] Open
Abstract
Transient modification of the environment involves the expression of specific genes and
degradation of mRNAs and proteins. How these events are linked is poorly understood.
CCR4-NOT is an evolutionary conserved complex involved in transcription initiation and
mRNA degradation. In this paper, we report that the yeast Not4 localizes in cytoplasmic
foci after cellular stress. We focused our attention on the functional characterization of
the C-terminus of the Not4 protein. Molecular dissection of this region indicates that the
removal of the last 120 amino acids, does not affect protein localization and function, in
that the protein is still able to suppress the thermosensitivity observed in the
not4Δ mutant. In addition, such shortened form of Not4, as well its
absence, increases the transcription of stress-responsive genes conferring to the cell
high resistance to the oxidative stress. On the contrary, the last C-terminal 211 amino
acids are required for proper Not4 localization at cytoplasmic foci after stress. This
truncated version of Not4 fails to increase the transcription of the stress genes, is more
stable and seems to be toxic to cells undergoing oxidative stress.
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Affiliation(s)
- Vanessa Palermo
- Department of Biology and Biotechnology "C. Darwin", Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy
| | - Mariarita Stirpe
- Department of Biology and Biotechnology "C. Darwin", Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy
| | - Michele Maria Bianchi
- Department of Biology and Biotechnology "C. Darwin", Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy
| | - Teresa Rinaldi
- Department of Biology and Biotechnology "C. Darwin", Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy
| | - Angela Cirigliano
- Department of Biology and Biotechnology "C. Darwin", Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy
| | - Antonella Ragnini-Wilson
- Department of Biology, University of Tor Vergata Rome, Viale Della Ricerca Scientifica, 00133 Rome, Italy
| | - Claudio Falcone
- Department of Biology and Biotechnology "C. Darwin", Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy
| | - Cristina Mazzoni
- Department of Biology and Biotechnology "C. Darwin", Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Piazzale A. Moro 5, 00185 Rome, Italy
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4
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Tian J, Lu Z, Niu S, Zhang S, Ying P, Wang L, Zhang M, Cai Y, Dong T, Zhu Y, Zhong R, Wang Z, Chang J, Miao X. Aberrant MCM10 SUMOylation induces genomic instability mediated by a genetic variant associated with survival of esophageal squamous cell carcinoma. Clin Transl Med 2021; 11:e485. [PMID: 34185429 PMCID: PMC8236122 DOI: 10.1002/ctm2.485] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 06/13/2021] [Accepted: 06/16/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Esophageal squamous cell carcinoma (ESCC) is one of the common gastrointestinal malignancy with an inferior prognosis outcome. DNA replication licensing aberration induced by dysregulation of minichromosome maintenance proteins (MCMs) causes genomic instability and cancer metastasis. SUMOylation modification plays a pivotal role in regulation of genomic integrity, while its dysregulation fueled by preexisting germline variants in cancers remains poorly understood. METHODS Firstly, we conducted two-stage survival analysis consisting of an exome-wide association study in 904 ESCC samples and another independent 503 ESCC samples. Then, multipronged functional experiments were performed to illuminate the potential biological mechanisms underlying the promising variants, and MCM10 influences the ESCC progression. Finally, we tested the effects of MCM10 inhibitors on ESCC cells. RESULTS A germline variant rs2274110 located at the exon 15 of MCM10 was identified to be significantly associated with the prognosis of ESCC patients. Individuals carrying rs2274110-AA genotypes confer a poor survival (hazard ratio = 1.61, 95% confidence interval = 1.35-1.93, p = 1.35 × 10-7 ), compared with subjects carrying rs2274110-AG/GG genotypes. Furthermore, we interestingly found that the variant can increase SUMOylation levels at K669 site (Lys[K]699Arg[R]) of MCM10 protein mediated by SUMO2/3 enzymes, which resulted in an aberrant overexpression of MCM10. Mechanistically, aberrant overexpression of MCM10 facilitated the proliferation and metastasis abilities of ESCC cells in vitro and in vivo by inducing DNA over-replication and genomic instability, providing functional evidence to support our population finding that high expression of MCM10 is extensively presented in tumor tissues of ESCC and correlated with inferior survival outcomes of multiple cancer types, including ESCC. Finally, MCM10 inhibitors Suramin and its analogues were revealed to effectively block the metastasis of ESCC cells. CONCLUSIONS These findings not only demonstrate a potential biological mechanism between aberrant SUMOylation, genomic instability and cancer metastasis, but also provide a promising biomarker aiding in stratifying ESCC individuals with different prognosis, as well as a potential therapeutic target MCM10.
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Affiliation(s)
- Jianbo Tian
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Zequn Lu
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Siyuan Niu
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Shanshan Zhang
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Pingting Ying
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Lu Wang
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Ming Zhang
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Yimin Cai
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Tianyi Dong
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Ying Zhu
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Rong Zhong
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Zhihua Wang
- Department of UrologyTongji HospitalTongji Medical CollegeHuazhong University of Science and TechnologyWuhanChina
| | - Jiang Chang
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
| | - Xiaoping Miao
- Department of Epidemiology and BiostatisticsKey Laboratory for Environment and HealthSchool of Public HealthTongji Medical CollegeHuazhong University of Sciences and TechnologyWuhanChina
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5
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Arlow T, Kim J, Haye-Bertolozzi JE, Martínez CB, Fay C, Zorensky E, Rose MD, Gammie AE. MutSα mismatch repair protein stability is governed by subunit interaction, acetylation, and ubiquitination. G3 (BETHESDA, MD.) 2021; 11:jkaa065. [PMID: 33793773 PMCID: PMC8063085 DOI: 10.1093/g3journal/jkaa065] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 12/14/2020] [Indexed: 11/13/2022]
Abstract
In eukaryotes, DNA mismatch recognition is accomplished by the highly conserved MutSα (Msh2/Msh6) and MutSβ (Msh2/Msh3) complexes. Previously, in the yeast Saccharomyces cerevisiae, we determined that deleting MSH6 caused wild-type Msh2 levels to drop by ∼50%. In this work, we determined that Msh6 steady-state levels are coupled to increasing or decreasing levels of Msh2. Although Msh6 and Msh2 are reciprocally regulated, Msh3 and Msh2 are not. Msh2 missense variants that are able to interact with Msh6 were destabilized when Msh6 was deleted; in contrast, variants that fail to dimerize were not further destabilized in cells lacking Msh6. In the absence of Msh6, Msh2 is turned over at a faster rate and degradation is mediated by the ubiquitin-proteasome pathway. Mutagenesis of certain conserved lysines near the dimer interface restored the levels of Msh2 in the absence of Msh6, further supporting a dimer stabilization mechanism. We identified two alternative forms of regulation both with the potential to act via lysine residues, including acetylation by Gcn5 and ubiquitination by the Not4 ligase. In the absence of Gcn5, Msh2 levels were significantly decreased; in contrast, deleting Not4 stabilized Msh2 and Msh2 missense variants with partial function. The stabilizing effect on Msh2 by either the presence of Msh6 or the absence of Not4 are dependent on Gcn5. Taken together, the results suggest that the wild-type MutSα mismatch repair protein stability is governed by subunit interaction, acetylation, and ubiquitination.
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Affiliation(s)
- Tim Arlow
- Ophthalmic Associates, Johnstown, PA
| | | | | | | | | | | | - Mark D. Rose
- Georgetown University, Georgetown, Washington D.C
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6
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Dhakal S, Macreadie I. Protein Homeostasis Networks and the Use of Yeast to Guide Interventions in Alzheimer's Disease. Int J Mol Sci 2020; 21:E8014. [PMID: 33126501 PMCID: PMC7662794 DOI: 10.3390/ijms21218014] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/24/2020] [Accepted: 10/26/2020] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's Disease (AD) is a progressive multifactorial age-related neurodegenerative disorder that causes the majority of deaths due to dementia in the elderly. Although various risk factors have been found to be associated with AD progression, the cause of the disease is still unresolved. The loss of proteostasis is one of the major causes of AD: it is evident by aggregation of misfolded proteins, lipid homeostasis disruption, accumulation of autophagic vesicles, and oxidative damage during the disease progression. Different models have been developed to study AD, one of which is a yeast model. Yeasts are simple unicellular eukaryotic cells that have provided great insights into human cell biology. Various yeast models, including unmodified and genetically modified yeasts, have been established for studying AD and have provided significant amount of information on AD pathology and potential interventions. The conservation of various human biological processes, including signal transduction, energy metabolism, protein homeostasis, stress responses, oxidative phosphorylation, vesicle trafficking, apoptosis, endocytosis, and ageing, renders yeast a fascinating, powerful model for AD. In addition, the easy manipulation of the yeast genome and availability of methods to evaluate yeast cells rapidly in high throughput technological platforms strengthen the rationale of using yeast as a model. This review focuses on the description of the proteostasis network in yeast and its comparison with the human proteostasis network. It further elaborates on the AD-associated proteostasis failure and applications of the yeast proteostasis network to understand AD pathology and its potential to guide interventions against AD.
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Affiliation(s)
| | - Ian Macreadie
- School of Science, RMIT University, Bundoora, Victoria 3083, Australia;
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7
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Abstract
The Ccr4-Not complex is an essential multi-subunit protein complex that plays a fundamental role in eukaryotic mRNA metabolism and has a multitude of different roles that impact eukaryotic gene expression . It has a conserved core of three Not proteins, the Ccr4 protein, and two Ccr4 associated factors, Caf1 and Caf40. A fourth Not protein, Not4, is conserved, but is only a stable subunit of the complex in yeast. Certain subunits have been duplicated during evolution, with functional divergence, such as Not3 in yeast, and Ccr4 or Caf1 in human. However the complex includes only one homolog for each protein. In addition, species-specific subunits are part of the complex, such as Caf130 in yeast or Not10 and Not11 in human. Two conserved catalytic functions are associated with the complex, deadenylation and ubiquitination . The complex adopts an L-shaped structure, in which different modules are bound to a large Not1 scaffold protein. In this chapter we will summarize our current knowledge of the architecture of the complex and of the structure of its constituents.
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Affiliation(s)
- Martine A Collart
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, Geneva, Switzerland.
| | - Olesya O Panasenko
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, 1 rue Michel Servet, Geneva, Switzerland
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8
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Yang WD, Wang L. MCM10 facilitates the invaded/migrated potentials of breast cancer cells via Wnt/β-catenin signaling and is positively interlinked with poor prognosis in breast carcinoma. J Biochem Mol Toxicol 2019; 33:e22330. [PMID: 30990947 DOI: 10.1002/jbt.22330] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/27/2019] [Accepted: 03/15/2019] [Indexed: 12/16/2022]
Abstract
The minichromosome maintenance protein 10 (MCM10) is one of the MCM proteins that initiate DNA replication by interacting with CDC45-MCM2-7. It has been reported that MCM10 has a role in breast cancer progression. However, MCM10 in breast cancer is still not comprehensively studied and further research is needed. This study was aimed at investigating the potential effects of MCM10 on metastasis, the prognosis of breast carcinoma, and its underlying mechanisms. Using the ONCOMINE database and the Kaplan-Meier Plotter, MCM10 was significantly overexpressed in cancers, and high expression of MCM10 was involved in the poor prognosis of breast carcinoma. MCM10 can promote the proliferation, migration, and invasion of MDA-MB-231 cells. MCM10 knockdown brought about a radical reversal in cell behaviors. Meanwhile, decreased expression of β-catenin and cyclin Dl was detected in MCM10 short hairpin RNA cells, implying that MCM10 might induce breast cancer metastasis via the Wnt/β-catenin pathway.MCM10 can be defined as a potential diagnostic tool and a promising target for breast carcinoma.
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Affiliation(s)
- Wei-Dong Yang
- Department of Thyroid and Breast Surgery, People's Hospital of Three Gorges University, Yichang, Hubei, China
| | - Lu Wang
- Department of Thyroid and Breast Surgery, People's Hospital of Three Gorges University, Yichang, Hubei, China
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9
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Vo N, Anh Suong DN, Yoshino N, Yoshida H, Cotterill S, Yamaguchi M. Novel roles of HP1a and Mcm10 in DNA replication, genome maintenance and photoreceptor cell differentiation. Nucleic Acids Res 2017; 45:1233-1254. [PMID: 28180289 PMCID: PMC5388399 DOI: 10.1093/nar/gkw1174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 11/04/2016] [Accepted: 11/13/2016] [Indexed: 01/21/2023] Open
Abstract
Both Mcm10 and HP1a are known to be required for DNA replication. However, underlying mechanism is not clarified yet especially for HP1. Knockdown of both HP1a and Mcm10 genes inhibited the progression of S phase in Drosophila eye imaginal discs. Proximity Ligation Assay (PLA) demonstrated that HP1a is in close proximity to DNA replication proteins including Mcm10, RFC140 and DNA polymerase ε 255 kDa subunit in S-phase. This was further confirmed by co-immunoprecipitation assay. The PLA signals between Mcm10 and HP1a are specifically observed in the mitotic cycling cells, but not in the endocycling cells. Interestingly, many cells in the posterior regions of eye imaginal discs carrying a double knockdown of Mcm10 and HP1a induced ectopic DNA synthesis and DNA damage without much of ectopic apoptosis. Therefore, the G1-S checkpoint may be affected by knockdown of both proteins. This event was also the case with other HP family proteins such as HP4 and HP6. In addition, both Mcm10 and HP1a are required for differentiation of photoreceptor cells R1, R6 and R7. Further analyses on several developmental genes involved in the photoreceptor cell differentiation suggest that a role of both proteins is mediated by regulation of the lozenge gene.
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Affiliation(s)
- Nicole Vo
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Dang Ngoc Anh Suong
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Natsuki Yoshino
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Hideki Yoshida
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
| | - Sue Cotterill
- Department of Basic Medical Sciences, St Georges, University of London, London, UK
| | - Masamitsu Yamaguchi
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,The Center for Advanced Insect Research, Kyoto Institute of Technology, Kyoto, Japan
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10
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Simonetti F, Candelli T, Leon S, Libri D, Rougemaille M. Ubiquitination-dependent control of sexual differentiation in fission yeast. eLife 2017; 6:28046. [PMID: 28841135 PMCID: PMC5614563 DOI: 10.7554/elife.28046] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/21/2017] [Indexed: 01/03/2023] Open
Abstract
In fission yeast, meiosis-specific transcripts are selectively eliminated during vegetative growth by the combined action of the YTH-family RNA-binding protein Mmi1 and the nuclear exosome. Upon nutritional starvation, the master regulator of meiosis Mei2 inactivates Mmi1, thereby allowing expression of the meiotic program. Here, we show that the E3 ubiquitin ligase subunit Not4/Mot2 of the evolutionarily conserved Ccr4-Not complex, which associates with Mmi1, promotes suppression of meiotic transcripts expression in mitotic cells. Our analyses suggest that Mot2 directs ubiquitination of Mei2 to preserve the activity of Mmi1 during vegetative growth. Importantly, Mot2 is not involved in the constitutive pathway of Mei2 turnover, but rather plays a regulatory role to limit its accumulation or inhibit its function. We propose that Mmi1 recruits the Ccr4-Not complex to counteract its own inhibitor Mei2, thereby locking the system in a stable state that ensures the repression of the meiotic program by Mmi1.
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Affiliation(s)
- Fabrizio Simonetti
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Tito Candelli
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.,Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sebastien Leon
- Institut Jacques Monod, Team "Membrane Trafficking, Ubiquitin and Signaling", CNRS, UMR9198, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Domenico Libri
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Mathieu Rougemaille
- Institut Jacques Monod, Team "Metabolism and Function of RNA in the Nucleus", CNRS, UMR7592, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
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11
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Preissler S, Reuther J, Koch M, Scior A, Bruderek M, Frickey T, Deuerling E. Not4-dependent translational repression is important for cellular protein homeostasis in yeast. EMBO J 2015; 34:1905-24. [PMID: 25971775 DOI: 10.15252/embj.201490194] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 04/12/2015] [Indexed: 11/09/2022] Open
Abstract
Translation of aberrant or problematic mRNAs can cause ribosome stalling which leads to the production of truncated or defective proteins. Therefore, cells evolved cotranslational quality control mechanisms that eliminate these transcripts and target arrested nascent polypeptides for proteasomal degradation. Here we show that Not4, which is part of the multifunctional Ccr4-Not complex in yeast, associates with polysomes and contributes to the negative regulation of protein synthesis. Not4 is involved in translational repression of transcripts that cause transient ribosome stalling. The absence of Not4 affected global translational repression upon nutrient withdrawal, enhanced the expression of arrested nascent polypeptides and caused constitutive protein folding stress and aggregation. Similar defects were observed in cells with impaired mRNA decapping protein function and in cells lacking the mRNA decapping activator and translational repressor Dhh1. The results suggest a role for Not4 together with components of the decapping machinery in the regulation of protein expression on the mRNA level and emphasize the importance of translational repression for the maintenance of proteome integrity.
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Affiliation(s)
- Steffen Preissler
- Molecular Microbiology, University of Konstanz, Konstanz, Germany Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Julia Reuther
- Molecular Microbiology, University of Konstanz, Konstanz, Germany Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Miriam Koch
- Molecular Microbiology, University of Konstanz, Konstanz, Germany Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Annika Scior
- Molecular Microbiology, University of Konstanz, Konstanz, Germany Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Michael Bruderek
- Molecular Microbiology, University of Konstanz, Konstanz, Germany
| | - Tancred Frickey
- Applied Bioinformatics, University of Konstanz, Konstanz, Germany
| | - Elke Deuerling
- Molecular Microbiology, University of Konstanz, Konstanz, Germany
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12
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Alver RC, Zhang T, Josephrajan A, Fultz BL, Hendrix CJ, Das-Bradoo S, Bielinsky AK. The N-terminus of Mcm10 is important for interaction with the 9-1-1 clamp and in resistance to DNA damage. Nucleic Acids Res 2014; 42:8389-404. [PMID: 24972833 PMCID: PMC4117747 DOI: 10.1093/nar/gku479] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Accurate replication of the genome requires the evolutionarily conserved minichromosome maintenance protein, Mcm10. Although the details of the precise role of Mcm10 in DNA replication are still debated, it interacts with the Mcm2-7 core helicase, the lagging strand polymerase, DNA polymerase-α and the replication clamp, proliferating cell nuclear antigen. Loss of these interactions caused by the depletion of Mcm10 leads to chromosome breakage and cell cycle checkpoint activation. However, whether Mcm10 has an active role in DNA damage prevention is unknown. Here, we present data that establish a novel role of the N-terminus of Mcm10 in resisting DNA damage. We show that Mcm10 interacts with the Mec3 subunit of the 9-1-1 clamp in response to replication stress evoked by UV irradiation or nucleotide shortage. We map the interaction domain with Mec3 within the N-terminal region of Mcm10 and demonstrate that its truncation causes UV light sensitivity. This sensitivity is not further enhanced by a deletion of MEC3, arguing that MCM10 and MEC3 operate in the same pathway. Since Rad53 phosphorylation in response to UV light appears to be normal in N-terminally truncated mcm10 mutants, we propose that Mcm10 may have a role in replication fork restart or DNA repair.
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Affiliation(s)
- Robert C Alver
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Tianji Zhang
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ajeetha Josephrajan
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brandy L Fultz
- Department of Natural Sciences, Northeastern State University, 3100 East New Orleans Street, Broken Arrow, OK 74012, USA
| | - Chance J Hendrix
- Department of Natural Sciences, Northeastern State University, 3100 East New Orleans Street, Broken Arrow, OK 74012, USA
| | - Sapna Das-Bradoo
- Department of Natural Sciences, Northeastern State University, 3100 East New Orleans Street, Broken Arrow, OK 74012, USA
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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13
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Becker JR, Nguyen HD, Wang X, Bielinsky AK. Mcm10 deficiency causes defective-replisome-induced mutagenesis and a dependency on error-free postreplicative repair. Cell Cycle 2014; 13:1737-48. [PMID: 24674891 DOI: 10.4161/cc.28652] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mcm10 is a multifunctional replication factor with reported roles in origin activation, polymerase loading, and replication fork progression. The literature supporting these variable roles is controversial, and it has been debated whether Mcm10 has an active role in elongation. Here, we provide evidence that the mcm10-1 allele confers alterations in DNA synthesis that lead to defective-replisome-induced mutagenesis (DRIM). Specifically, we observed that mcm10-1 cells exhibited elevated levels of PCNA ubiquitination and activation of the translesion polymerase, pol-ζ. Whereas translesion synthesis had no measurable impact on viability, mcm10-1 mutants also engaged in error-free postreplicative repair (PRR), and this pathway promoted survival at semi-permissive conditions. Replication gaps in mcm10-1 were likely caused by elongation defects, as dbf4-1 mutants, which are compromised for origin activation did not display any hallmarks of replication stress. Furthermore, we demonstrate that deficiencies in priming, induced by a pol1-1 mutation, also resulted in DRIM, but not in error-free PRR. Similar to mcm10-1 mutants, DRIM did not rescue the replication defect in pol1-1 cells. Thus, it appears that DRIM is not proficient to fill replication gaps in pol1-1 and mcm10-1 mutants. Moreover, the ability to correctly prime nascent DNA may be a crucial prerequisite to initiate error-free PRR.
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Affiliation(s)
- Jordan R Becker
- Department of Biochemistry, Molecular Biology, and Biophysics; University of Minnesota; Minneapolis, MN USA
| | - Hai Dang Nguyen
- Department of Biochemistry, Molecular Biology, and Biophysics; University of Minnesota; Minneapolis, MN USA
| | - Xiaohan Wang
- Department of Biochemistry, Molecular Biology, and Biophysics; University of Minnesota; Minneapolis, MN USA
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology, and Biophysics; University of Minnesota; Minneapolis, MN USA
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14
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Thu YM, Bielinsky AK. MCM10: one tool for all-Integrity, maintenance and damage control. Semin Cell Dev Biol 2014; 30:121-30. [PMID: 24662891 DOI: 10.1016/j.semcdb.2014.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 03/10/2014] [Indexed: 01/16/2023]
Abstract
Minichromsome maintenance protein 10 (Mcm10) is an essential replication factor that is required for the activation of the Cdc45:Mcm2-7:GINS helicase. Mcm10's ability to bind both ds and ssDNA appears vital for this function. In addition, Mcm10 interacts with multiple players at the replication fork, including DNA polymerase-α and proliferating cell nuclear antigen with which it cooperates during DNA elongation. Mcm10 lacks enzymatic function, but instead provides the replication apparatus with an oligomeric scaffold that likely acts in the coordination of DNA unwinding and DNA synthesis. Not surprisingly, loss of Mcm10 engages checkpoint, DNA repair and SUMO-dependent rescue pathways that collectively counteract replication stress and chromosome breakage. Here, we review Mcm10's structure and function and explain how it contributes to the maintenance of genome integrity.
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Affiliation(s)
- Yee Mon Thu
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, United States.
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15
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Mcm10 self-association is mediated by an N-terminal coiled-coil domain. PLoS One 2013; 8:e70518. [PMID: 23894664 PMCID: PMC3720919 DOI: 10.1371/journal.pone.0070518] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 06/11/2013] [Indexed: 01/13/2023] Open
Abstract
Minichromosome maintenance protein 10 (Mcm10) is an essential eukaryotic DNA-binding replication factor thought to serve as a scaffold to coordinate enzymatic activities within the replisome. Mcm10 appears to function as an oligomer rather than in its monomeric form (or rather than as a monomer). However, various orthologs have been found to contain 1, 2, 3, 4, or 6 subunits and thus, this issue has remained controversial. Here, we show that self-association of Xenopus laevis Mcm10 is mediated by a conserved coiled-coil (CC) motif within the N-terminal domain (NTD). Crystallographic analysis of the CC at 2.4 Å resolution revealed a three-helix bundle, consistent with the formation of both dimeric and trimeric Mcm10 CCs in solution. Mutation of the side chains at the subunit interface disrupted in vitro dimerization of both the CC and the NTD as monitored by analytical ultracentrifugation. In addition, the same mutations also impeded self-interaction of the full-length protein in vivo, as measured by yeast-two hybrid assays. We conclude that Mcm10 likely forms dimers or trimers to promote its diverse functions during DNA replication.
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16
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Inada T. Quality control systems for aberrant mRNAs induced by aberrant translation elongation and termination. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:634-42. [PMID: 23416749 DOI: 10.1016/j.bbagrm.2013.02.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2012] [Revised: 02/01/2013] [Accepted: 02/02/2013] [Indexed: 10/27/2022]
Abstract
RNA processing is an essential gene expression step and plays a crucial role to achieve diversity of gene products in eukaryotes. Various aberrant mRNAs transiently produced during RNA processing reactions are recognized and eliminated by specific quality control systems. It has been demonstrated that these mRNA quality control systems stimulate the degradation of aberrant mRNA to prevent the potentially harmful products derived from aberrant mRNAs. Recent studies on quality control systems induced by abnormal translation elongation and termination have revealed that both aberrant mRNAs and proteins are subjected to rapid degradation. In NonStop Decay (NSD) quality control system, a poly(A) tail of nonstop mRNA is translated and the synthesis of poly-lysine sequence results in translation arrest followed by co-translational degradation of aberrant nonstop protein. In No-Go Decay (NGD) quality control system, the specific amino acid sequences of the nascent polypeptide induce ribosome stalling, and the arrest products are ubiquitinated and rapidly degraded by the proteasome. In Nonfunctional rRNA Decay (NRD) quality control system, aberrant ribosomes composed of nonfunctional ribosomal RNAs are also eliminated when aberrant translation elongation complexes are formed on mRNA. I describe recent progresses on the mechanisms of quality control systems and the relationships between quality control systems. This article is part of a Special issue entitled: RNA Decay mechanisms.
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17
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Wahle E, Winkler GS. RNA decay machines: deadenylation by the Ccr4-not and Pan2-Pan3 complexes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:561-70. [PMID: 23337855 DOI: 10.1016/j.bbagrm.2013.01.003] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/14/2012] [Accepted: 01/09/2013] [Indexed: 12/20/2022]
Abstract
Shortening and removal of the 3' poly(A) tail of mature mRNA by poly(A)-specific 3' exonucleases (deadenylases) is the initial and often rate-limiting step in mRNA degradation. The majority of cytoplasmic deadenylase activity is associated with the Ccr4-Not and Pan2-Pan3 complexes. Two distinct catalytic subunits, Caf1/Pop2 and Ccr4, are associated with the Ccr4-Not complex, whereas the Pan2 enzymatic subunit forms a stable complex with Pan3. In this review, we discuss the composition and activity of these two deadenylases. In addition, we comment on generic and specific mechanisms of recruitment of Ccr4-Not and Pan2-Pan3 to mRNAs. Finally, we discuss specialised and redundant functions of the deadenylases and review the importance of Ccr4-Not subunits in the regulation of physiological processes. This article is part of a Special Issue entitled: RNA Decay mechanisms.
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Affiliation(s)
- Elmar Wahle
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Halle, Germany.
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18
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Thu YM, Bielinsky AK. Enigmatic roles of Mcm10 in DNA replication. Trends Biochem Sci 2013; 38:184-94. [PMID: 23332289 DOI: 10.1016/j.tibs.2012.12.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2012] [Revised: 11/30/2012] [Accepted: 12/07/2012] [Indexed: 12/31/2022]
Abstract
Minichromosome maintenance protein 10 (Mcm10) is required for DNA replication in all eukaryotes. Although the exact contribution of Mcm10 to genome replication remains heavily debated, early reports suggested that it promotes DNA unwinding and origin firing. These ideas have been solidified by recent studies that propose a role for Mcm10 in helicase activation. Whereas the molecular underpinnings of this activation step have yet to be revealed, structural data on Mcm10 provide further insight into a possible mechanism of action. The essential role in DNA replication initiation is not mutually exclusive with additional functions that Mcm10 may have as part of the elongation machinery. Here, we review the recent findings regarding the role of Mcm10 in DNA replication and discuss existing controversies.
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Affiliation(s)
- Yee Mon Thu
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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19
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Reese JC. The control of elongation by the yeast Ccr4-not complex. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1829:127-33. [PMID: 22975735 PMCID: PMC3545033 DOI: 10.1016/j.bbagrm.2012.09.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 08/30/2012] [Accepted: 09/03/2012] [Indexed: 12/12/2022]
Abstract
The Ccr4-Not complex is a highly conserved nine-subunit protein complex that has been implicated in virtually all aspects of gene control, including transcription, mRNA decay and quality control, RNA export, translational repression and protein ubiquitylation. Understanding its mechanisms of action has been difficult due to the size of the complex and the fact that it regulates mRNAs and proteins at many levels in both the cytoplasm and the nucleus. Recently, biochemical and genetic studies on the yeast Ccr4-Not complex have revealed insights into its role in promoting elongation by RNA polymerase II. This review will describe what is known about the Ccr4-Not complex in regulating transcription elongation and its possible collaboration with other factors traveling with RNAPII across genes. This article is part of a Special Issue entitled: RNA polymerase II Transcript Elongation.
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Affiliation(s)
- Joseph C Reese
- Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA 16802, USA.
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20
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Abstract
The purpose of this review is to provide an analysis of the latest developments on the functions of the carbon catabolite-repression 4-Not (Ccr4-Not) complex in regulating eukaryotic gene expression. Ccr4-Not is a nine-subunit protein complex that is conserved in sequence and function throughout the eukaryotic kingdom. Although Ccr4-Not has been studied since the 1980s, our understanding of what it does is constantly evolving. Once thought to solely regulate transcription, it is now clear that it has much broader roles in gene regulation, such as in mRNA decay and quality control, RNA export, translational repression and protein ubiquitylation. The mechanism of actions for each of its functions is still being debated. Some of the difficulty in drawing a clear picture is that it has been implicated in so many processes that regulate mRNAs and proteins in both the cytoplasm and the nucleus. We will describe what is known about the Ccr4-Not complex in yeast and other eukaryotes in an effort to synthesize a unified model for how this complex coordinates multiple steps in gene regulation and provide insights into what questions will be most exciting to answer in the future.
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Affiliation(s)
- Jason E. Miller
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, Center for RNA Molecular Biology, Penn State University, University Park, PA 16802
| | - Joseph C. Reese
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, Center for RNA Molecular Biology, Penn State University, University Park, PA 16802
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21
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Gulshan K, Thommandru B, Moye-Rowley WS. Proteolytic degradation of the Yap1 transcription factor is regulated by subcellular localization and the E3 ubiquitin ligase Not4. J Biol Chem 2012; 287:26796-805. [PMID: 22707721 DOI: 10.1074/jbc.m112.384719] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Saccharomyces cerevisiae Yap1 is a transcriptional regulatory protein that serves as a central determinant of oxidative stress tolerance. Activity of this factor is regulated in large part by control of its subcellular location. In the absence of oxidants, Yap1 is primarily located in the cytoplasm. Upon oxidant challenge, Yap1 accumulates rapidly in the nucleus where it activates expression of genes required for oxidative stress tolerance such as the thioredoxin TRX2. Here, we demonstrate that Yap1 degradation is accelerated in response to oxidative stress. Yap1 is folded differently depending on the oxidant used to induce its nuclear localization but is degraded similarly, irrespective of its folded status. Mutant forms of Yap1 that are constitutively trapped in the nucleus are degraded in the absence of an oxidant signal. Degradation requires the ability of the protein to bind DNA and a domain in the amino-terminal region of the factor. Inhibition of the proteasome prevents Yap1 turnover. Screening a variety of mutants involved in ubiquitin-mediated proteolysis demonstrated an important role for the nuclear ubiquitin ligase Not4 in Yap1 degradation. Not4 was found to bind to Yap1 in an oxidant-stimulated fashion. The Candida albicans Yap1 homologue (Cap1) also was degraded after oxidant challenge. These data uncover a new, conserved pathway for regulation of the oxidative stress response that serves to temporally limit the duration of Yap1-dependent transcriptional activation.
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Affiliation(s)
- Kailash Gulshan
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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22
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Huo L, Wu R, Yu Z, Zhai Y, Yang X, Chan TC, Yeung JTF, Kan J, Liang C. The Rix1 (Ipi1p-2p-3p) complex is a critical determinant of DNA replication licensing independent of their roles in ribosome biogenesis. Cell Cycle 2012; 11:1325-39. [PMID: 22421151 DOI: 10.4161/cc.19709] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Several replication-initiation proteins are assembled stepwise onto replicators to form pre-replicative complexes (pre-RCs) to license eukaryotic DNA replication. We performed a yeast functional proteomic screen and identified the Rix1 complex members (Ipi1p-Ipi2p/Rix1-Ipi3p) as pre-RC components and critical determinants of replication licensing and replication-initiation frequency. Ipi3p interacts with pre-RC proteins, binds chromatin predominantly at ARS sequences in a cell cycle-regulated and ORC- and Noc3p-dependent manner and is required for loading Cdc6p, Cdt1p and MCM onto chromatin to form pre-RC during the M-to-G₁ transition and for pre-RC maintenance in G₁ phase-independent of its role in ribosome biogenesis. Moreover, Ipi1p and Ipi2p, but not other ribosome biogenesis proteins Rea1p and Utp1p, are also required for pre-RC formation and maintenance, and Ipi1p, -2p and -3p are interdependent for their chromatin association and function in pre-RC formation. These results establish a new framework for the hierarchy of pre-RC proteins, where the Ipi1p-2p-3p complex provides a critical link between ORC-Noc3p and Cdc6p-Cdt1p-MCM in replication licensing.
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Affiliation(s)
- Lin Huo
- Division of Life Science, Center for Cancer Research and State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China
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23
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Liu X, Lee YJ, Liou LC, Ren Q, Zhang Z, Wang S, Witt SN. Alpha-synuclein functions in the nucleus to protect against hydroxyurea-induced replication stress in yeast. Hum Mol Genet 2011; 20:3401-14. [PMID: 21642386 DOI: 10.1093/hmg/ddr246] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hydroxyurea (HU) inhibits ribonucleotide reductase (RNR), which catalyzes the rate-limiting synthesis of deoxyribonucleotides for DNA replication. HU is used to treat HIV, sickle-cell anemia and some cancers. We found that, compared with vector control cells, low levels of alpha-synuclein (α-syn) protect S. cerevisiae cells from the growth inhibition and reactive oxygen species (ROS) accumulation induced by HU. Analysis of this effect using different α-syn mutants revealed that the α-syn protein functions in the nucleus and not the cytoplasm to modulate S-phase checkpoint responses: α-syn up-regulates histone acetylation and RNR levels, maintains helicase minichromosome maintenance protein complexes (Mcm2-7) on chromatin and inhibits HU-induced ROS accumulation. Strikingly, when residues 2-10 or 96-140 are deleted, this protective function of α-syn in the nucleus is abolished. Understanding the mechanism by which α-syn protects against HU could expand our knowledge of the normal function of this neuronal protein.
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Affiliation(s)
- Xianpeng Liu
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA
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