1
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Schmit MM, Baxley RM, Wang L, Hinderlie P, Kaufman M, Simon E, Raju A, Miller JS, Bielinsky AK. A critical threshold of MCM10 is required to maintain genome stability during differentiation of induced pluripotent stem cells into natural killer cells. Open Biol 2024; 14:230407. [PMID: 38262603 PMCID: PMC10805602 DOI: 10.1098/rsob.230407] [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: 11/01/2023] [Accepted: 11/23/2023] [Indexed: 01/25/2024] Open
Abstract
Natural killer (NK) cell deficiency (NKD) is a rare disease in which NK cell function is reduced, leaving affected individuals susceptible to repeated viral infections and cancer. Recently, a patient with NKD was identified carrying compound heterozygous variants of MCM10 (minichromosome maintenance protein 10), an essential gene required for DNA replication, that caused a significant decrease in the amount of functional MCM10. NKD in this patient presented as loss of functionally mature late-stage NK cells. To understand how MCM10 deficiency affects NK cell development, we generated MCM10 heterozygous (MCM10+/-) induced pluripotent stem cell (iPSC) lines. Analyses of these cell lines demonstrated that MCM10 was haploinsufficient, similar to results in other human cell lines. Reduced levels of MCM10 in mutant iPSCs was associated with impaired clonogenic survival and increased genomic instability, including micronuclei formation and telomere erosion. The severity of these phenotypes correlated with the extent of MCM10 depletion. Significantly, MCM10+/- iPSCs displayed defects in NK cell differentiation, exhibiting reduced yields of hematopoietic stem cells (HSCs). Although MCM10+/- HSCs were able to give rise to lymphoid progenitors, these did not generate mature NK cells. The lack of mature NK cells coincided with telomere erosion, suggesting that NKD caused by these MCM10 variants arose from the accumulation of genomic instability including degradation of chromosome ends.
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Affiliation(s)
- Megan M. Schmit
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Ryan M. Baxley
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Liangjun Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Peter Hinderlie
- Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, MN, USA
| | - Marissa Kaufman
- Division of Hematology, Oncology and Transplantation, University of Minnesota, Minneapolis, MN, USA
| | - Emily Simon
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Anjali Raju
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, USA
| | - Jeffrey S. Miller
- Division of Hematology, Oncology and Transplantation, 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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2
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Seo S, Patil SL, Ahn YO, Armetta J, Hegewisch-Solloa E, Castillo M, Guilz NC, Patel A, Corneo B, Borowiak M, Gunaratne P, Mace EM. iPSC-based modeling of helicase deficiency reveals impaired cell proliferation and increased apoptosis after NK cell lineage commitment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.25.559149. [PMID: 37808662 PMCID: PMC10557596 DOI: 10.1101/2023.09.25.559149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Cell proliferation is a ubiquitous process required for organismal development and homeostasis. However, individuals with partial loss-of-function variants in DNA replicative helicase components often present with immunodeficiency due to specific loss of natural killer (NK) cells. Such lineage-specific disease phenotypes raise questions on how the proliferation is regulated in cell type-specific manner. We aimed to understand NK cell-specific proliferative dynamics and vulnerability to impaired helicase function using iPSCs from individuals with NK cell deficiency (NKD) due to hereditary compound heterozygous GINS4 variants. We observed and characterized heterogeneous cell populations that arise during the iPSC differentiation along with NK cells. While overall cell proliferation decreased with differentiation, early NK cell precursors showed a short burst of cell proliferation. GINS4 deficiency induced replication stress in these early NK cell precursors, which are poised for apoptosis, and ultimately recapitulate the NKD phenotype.
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Affiliation(s)
- Seungmae Seo
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York NY 10032
| | - Sagar L Patil
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York NY 10032
| | - Yong-Oon Ahn
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York NY 10032
| | - Jacqueline Armetta
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York NY 10032
| | - Everardo Hegewisch-Solloa
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York NY 10032
| | - Micah Castillo
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA, 77204
| | - Nicole C Guilz
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York NY 10032
| | - Achchhe Patel
- Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY, USA, 10032
| | - Barbara Corneo
- Columbia Stem Cell Initiative, Columbia University Irving Medical Center, New York, NY, USA, 10032
| | - Malgorzata Borowiak
- Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznan, Poland
| | - Preethi Gunaratne
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA, 77204
| | - Emily M Mace
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York NY 10032
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3
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Guilz NC, Ahn YO, Seo S, Mace EM. Unwinding the Role of the CMG Helicase in Inborn Errors of Immunity. J Clin Immunol 2023; 43:847-861. [PMID: 36809597 PMCID: PMC10789183 DOI: 10.1007/s10875-023-01437-3] [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: 10/31/2022] [Accepted: 01/20/2023] [Indexed: 02/23/2023]
Abstract
Inborn errors of immunity (IEI) are a collection of diseases resulting from genetic causes that impact the immune system through multiple mechanisms. Natural killer cell deficiency (NKD) is one such IEI where natural killer (NK) cells are the main immune lineage affected. Though rare, the deficiency of several genes has been described as underlying causes of NKD, including MCM4, GINS1, MCM10 , and GINS4 , all of which are involved in the eukaryotic CMG helicase. The CMG helicase is made up of C DC45 – M CM – G INS and accessory proteins including MCM10. The CMG helicase plays a critical role in DNA replication by unwinding the double helix and enabling access of polymerases to single-stranded DNA, and thus helicase proteins are active in any proliferating cell. Replication stress, DNA damage, and cell cycle arrest are among the cellular phenotypes attributed to loss of function variants in CMG helicase proteins. Despite the ubiquitous function of the CMG helicase, NK cells have an apparent susceptibility to the deficiency of helicase proteins. This review will examine the role of the CMG helicase in inborn errors of immunity through the lens of NKD and further discuss why natural killer cells can be so strongly affected by helicase deficiency.
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Affiliation(s)
- Nicole C Guilz
- Vagelos College of Physicians and Surgeons, Department of Pediatrics, Columbia University Irving Medical Center, 630 W 168th St., New York, NY, 10032, USA
| | - Yong-Oon Ahn
- Vagelos College of Physicians and Surgeons, Department of Pediatrics, Columbia University Irving Medical Center, 630 W 168th St., New York, NY, 10032, USA
| | - Seungmae Seo
- Vagelos College of Physicians and Surgeons, Department of Pediatrics, Columbia University Irving Medical Center, 630 W 168th St., New York, NY, 10032, USA
| | - Emily M Mace
- Vagelos College of Physicians and Surgeons, Department of Pediatrics, Columbia University Irving Medical Center, 630 W 168th St., New York, NY, 10032, USA.
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4
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Conte MI, Poli MC, Taglialatela A, Leuzzi G, Chinn IK, Salinas SA, Rey-Jurado E, Olivares N, Veramendi-Espinoza L, Ciccia A, Lupski JR, Aldave Becerra JC, Mace EM, Orange JS. Partial loss-of-function mutations in GINS4 lead to NK cell deficiency with neutropenia. JCI Insight 2022; 7:e154948. [PMID: 36345943 PMCID: PMC9675456 DOI: 10.1172/jci.insight.154948] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 09/14/2022] [Indexed: 11/09/2022] Open
Abstract
Human NK cell deficiency (NKD) is a primary immunodeficiency in which the main clinically relevant immunological defect involves missing or dysfunctional NK cells. Here, we describe a familial NKD case in which 2 siblings had a substantive NKD and neutropenia in the absence of other immune system abnormalities. Exome sequencing identified compound heterozygous variants in Go-Ichi-Ni-San (GINS) complex subunit 4 (GINS4, also known as SLD5), an essential component of the human replicative helicase, which we demonstrate to have a damaging impact upon the expression and assembly of the GINS complex. Cells derived from affected individuals and a GINS4-knockdown cell line demonstrate delayed cell cycle progression, without signs of improper DNA synthesis or increased replication stress. By modeling partial GINS4 depletion in differentiating NK cells in vitro, we demonstrate the causal relationship between the genotype and the NK cell phenotype, as well as a cell-intrinsic defect in NK cell development. Thus, biallelic partial loss-of-function mutations in GINS4 define a potentially novel disease-causing gene underlying NKD with neutropenia. Together with the previously described mutations in other helicase genes causing NKD, and with the mild defects observed in other human cells, these variants underscore the importance of this pathway in NK cell biology.
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Affiliation(s)
- Matilde I. Conte
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - M. Cecilia Poli
- Faculty of Medicine, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
- Immunology and Rheumatology Unit, Hospital Roberto del Rio, Santiago, Chile
| | - Angelo Taglialatela
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, New York, USA
| | - Giuseppe Leuzzi
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, New York, USA
| | - Ivan K. Chinn
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
- Division of Immunology, Allergy, and Retrovirology, Texas Children’s Hospital, Houston, Texas, USA
| | - Sandra A. Salinas
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Emma Rey-Jurado
- Faculty of Medicine, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Nixa Olivares
- Faculty of Medicine, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Liz Veramendi-Espinoza
- Allergy and Clinical Immunology, Hospital Nacional Edgardo Rebagliati Martins, Lima, Peru
| | - Alberto Ciccia
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, New York, USA
| | - James R. Lupski
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | | | - Emily M. Mace
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Jordan S. Orange
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
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5
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Baxley RM, Leung W, Schmit MM, Matson JP, Yin L, Oram MK, Wang L, Taylor J, Hedberg J, Rogers CB, Harvey AJ, Basu D, Taylor JC, Pagnamenta AT, Dreau H, Craft J, Ormondroyd E, Watkins H, Hendrickson EA, Mace EM, Orange JS, Aihara H, Stewart GS, Blair E, Cook JG, Bielinsky AK. Bi-allelic MCM10 variants associated with immune dysfunction and cardiomyopathy cause telomere shortening. Nat Commun 2021; 12:1626. [PMID: 33712616 PMCID: PMC7955084 DOI: 10.1038/s41467-021-21878-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 02/11/2021] [Indexed: 12/22/2022] Open
Abstract
Minichromosome maintenance protein 10 (MCM10) is essential for eukaryotic DNA replication. Here, we describe compound heterozygous MCM10 variants in patients with distinctive, but overlapping, clinical phenotypes: natural killer (NK) cell deficiency (NKD) and restrictive cardiomyopathy (RCM) with hypoplasia of the spleen and thymus. To understand the mechanism of MCM10-associated disease, we modeled these variants in human cell lines. MCM10 deficiency causes chronic replication stress that reduces cell viability due to increased genomic instability and telomere erosion. Our data suggest that loss of MCM10 function constrains telomerase activity by accumulating abnormal replication fork structures enriched with single-stranded DNA. Terminally-arrested replication forks in MCM10-deficient cells require endonucleolytic processing by MUS81, as MCM10:MUS81 double mutants display decreased viability and accelerated telomere shortening. We propose that these bi-allelic variants in MCM10 predispose specific cardiac and immune cell lineages to prematurely arrest during differentiation, causing the clinical phenotypes observed in both NKD and RCM patients.
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Affiliation(s)
- Ryan M Baxley
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Wendy Leung
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Megan M Schmit
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Jacob Peter Matson
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Lulu Yin
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Marissa K Oram
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Liangjun Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - John Taylor
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jack Hedberg
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Colette B Rogers
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Adam J Harvey
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Debashree Basu
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Jenny C Taylor
- Wellcome Centre Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Oxford NIHR Biomedical Research Centre, Oxford, OX3 7BN, UK
| | - Alistair T Pagnamenta
- Wellcome Centre Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Oxford NIHR Biomedical Research Centre, Oxford, OX3 7BN, UK
| | - Helene Dreau
- Department of Haematology, University of Oxford, Oxford, OX3 7BN, UK
| | - Jude Craft
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Elizabeth Ormondroyd
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Emily M Mace
- Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Jordan S Orange
- Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Grant S Stewart
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Edward Blair
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jeanette Gowen Cook
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA.
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6
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Wdhd1 is essential for early mouse embryogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1868:119011. [PMID: 33716172 DOI: 10.1016/j.bbamcr.2021.119011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 03/02/2021] [Accepted: 03/07/2021] [Indexed: 12/12/2022]
Abstract
WD repeat and HMG-box DNA binding protein 1 (Wdhd1) is the mouse ortholog of budding yeast Chromosome Transmission Fidelity 4 (CTF4), the protein product of which integrates the MCM2-7 helicase and DNA polymerase α/primase complex to initiate DNA replication. Previous work in fruit flies, Xenopus egg extracts, and human cell lines suggest that Wdhd1 is required for efficient DNA synthesis. However, rigorous in vivo functional studies on Wdhd1 in mammals are unavailable. In the present study, we have successfully generated a Wdhd1 null allele in mice through CRISPR/Cas9-mediated genome editing to investigate the role of Wdhd1 in embryogenesis in vivo. We characterized Wdhd1 expression using quantitative reverse-transcription polymerase chain reaction, and assessed embryonic cell proliferation by histology in both pre- and peri-implantation embryos. While Wdhd1 heterozygous mutant mice were grossly normal and fertile, we observed a reduction in cell proliferation by the gastrulation stage in Wdhd1 homozygous null mutant embryos which severely hampered their growth and viability. These results indicate that Wdhd1 plays a major role in cell proliferation during embryogenesis in mice.
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7
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Mace EM, Paust S, Conte MI, Baxley RM, Schmit MM, Patil SL, Guilz NC, Mukherjee M, Pezzi AE, Chmielowiec J, Tatineni S, Chinn IK, Akdemir ZC, Jhangiani SN, Muzny DM, Stray-Pedersen A, Bradley RE, Moody M, Connor PP, Heaps AG, Steward C, Banerjee PP, Gibbs RA, Borowiak M, Lupski JR, Jolles S, Bielinsky AK, Orange JS. Human NK cell deficiency as a result of biallelic mutations in MCM10. J Clin Invest 2020; 130:5272-5286. [PMID: 32865517 PMCID: PMC7524476 DOI: 10.1172/jci134966] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 06/24/2020] [Indexed: 12/16/2022] Open
Abstract
Human natural killer cell deficiency (NKD) arises from inborn errors of immunity that lead to impaired NK cell development, function, or both. Through the understanding of the biological perturbations in individuals with NKD, requirements for the generation of terminally mature functional innate effector cells can be elucidated. Here, we report a cause of NKD resulting from compound heterozygous mutations in minichromosomal maintenance complex member 10 (MCM10) that impaired NK cell maturation in a child with fatal susceptibility to CMV. MCM10 has not been previously associated with monogenic disease and plays a critical role in the activation and function of the eukaryotic DNA replisome. Through evaluation of patient primary fibroblasts, modeling patient mutations in fibroblast cell lines, and MCM10 knockdown in human NK cell lines, we have shown that loss of MCM10 function leads to impaired cell cycle progression and induction of DNA damage-response pathways. By modeling MCM10 deficiency in primary NK cell precursors, including patient-derived induced pluripotent stem cells, we further demonstrated that MCM10 is required for NK cell terminal maturation and acquisition of immunological system function. Together, these data define MCM10 as an NKD gene and provide biological insight into the requirement for the DNA replisome in human NK cell maturation and function.
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Affiliation(s)
- Emily M. Mace
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Silke Paust
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, California, USA
| | - Matilde I. Conte
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Ryan M. Baxley
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Megan M. Schmit
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sagar L. Patil
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Nicole C. Guilz
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
| | - Malini Mukherjee
- Center for Human Immunobiology, Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics
| | - Ashley E. Pezzi
- Center for Human Immunobiology, Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics
| | - Jolanta Chmielowiec
- Center for Cell and Gene Therapy, and
- Molecular and Cellular Biology Department, Baylor College of Medicine, Houston, Texas, USA
| | - Swetha Tatineni
- Department of Pediatrics
- Department of BioSciences, Rice University, Houston, Texas, USA
| | - Ivan K. Chinn
- Department of Pediatrics
- Department of Molecular and Human Genetics and
| | | | - Shalini N. Jhangiani
- Department of Molecular and Human Genetics and
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Donna M. Muzny
- Department of Molecular and Human Genetics and
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Asbjørg Stray-Pedersen
- Norwegian National Unit for Newborn Screening, Division of Pediatric and Adolescent Medicine, Oslo, Norway
| | - Rachel E. Bradley
- Immunodeficiency Centre for Wales, University Hospital of Wales, Cardiff, Wales
| | - Mo Moody
- Immunodeficiency Centre for Wales, University Hospital of Wales, Cardiff, Wales
| | - Philip P. Connor
- Immunodeficiency Centre for Wales, University Hospital of Wales, Cardiff, Wales
| | - Adrian G. Heaps
- Department of Virology and Immunology, North Cumbria University Hospitals, Carlisle, United Kingdom
| | - Colin Steward
- Department of Paediatric Haematology, Oncology and Bone Marrow Transplantation, Bristol Royal Hospital for Children, Bristol, United Kingdom
| | - Pinaki P. Banerjee
- Center for Human Immunobiology, Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics
| | - Richard A. Gibbs
- Department of Molecular and Human Genetics and
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Malgorzata Borowiak
- Center for Cell and Gene Therapy, and
- Molecular and Cellular Biology Department, Baylor College of Medicine, Houston, Texas, USA
- Adam Mickiewicz University, Poznan, Poland
- McNair Medical Institute, Baylor College of Medicine, Houston, Texas, USA
| | - James R. Lupski
- Department of Pediatrics
- Department of Molecular and Human Genetics and
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Texas Children’s Hospital, Houston, Texas, USA
| | - Stephen Jolles
- Immunodeficiency Centre for Wales, University Hospital of Wales, Cardiff, Wales
| | - Anja K. Bielinsky
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Jordan S. Orange
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York, USA
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8
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Knockdown of MCM10 Gene Impairs Glioblastoma Cell Proliferation, Migration and Invasion and the Implications for the Regulation of Tumorigenesis. J Mol Neurosci 2020; 70:759-768. [PMID: 32030558 DOI: 10.1007/s12031-020-01486-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 01/17/2020] [Indexed: 10/24/2022]
Abstract
Minichromosome maintenance 10 (MCM10) plays an important role in DNA replication and is expressed in a variety of tumors, including glioma. However, its role and mechanism in glioma remain elusive. The purpose of this study was to examine the molecular function of MCM10 in glioblastoma cell lines in vitro and to further investigate the molecular mechanisms in the network mediated by MCM10. Cell proliferation, invasion, and migration were investigated in the absence of MCM10 mediated by RNA interference (RNAi) in U87 and U251 cell lines. Microarray data were obtained from U87 cells infected with a lentivirus expressing a small interfering RNA (siRNA) targeting MCM10, and ingenuity pathway analysis (IPA) was performed. Molecular signaling pathways, gene functions, and upstream and downstream regulatory genes and networks were analyzed. MCM10 was positively stained in human glioblastoma multiforme (GBM) samples according to immunohistochemistry. Silencing MCM10 in U87 and U251 cells significantly reduced cell proliferation, migration, and invasion. In U87 cells transfected with MCM10, 274 genes were significantly upregulated, while 313 genes were downregulated. IPA revealed that MCM10 is involved in the IGF-1 signaling pathway, and calcitriol appears to be a significant upstream regulator of MCM10. Other factors, such as TWIST1 and Stat3, also interact within the MCM10-mediated network. Our data indicate that MCM10 is involved in the regulation of GBM in vitro and may provide more evidence for understanding the molecular mechanisms of this fatal disease.
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9
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Mace EM, Orange JS. Emerging insights into human health and NK cell biology from the study of NK cell deficiencies. Immunol Rev 2019; 287:202-225. [PMID: 30565241 DOI: 10.1111/imr.12725] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Accepted: 09/28/2018] [Indexed: 12/24/2022]
Abstract
Human NK cells are innate immune effectors that play a critical roles in the control of viral infection and malignancy. The importance of their homeostasis and function can be demonstrated by the study of patients with primary immunodeficiencies (PIDs), which are part of the family of diseases known as inborn defects of immunity. While NK cells are affected in many PIDs in ways that may contribute to a patient's clinical phenotype, a small number of PIDs have an NK cell abnormality as their major immunological defect. These PIDs can be collectively referred to as NK cell deficiency (NKD) disorders and include effects upon NK cell numbers, subsets, and/or functions. The clinical impact of NKD can be severe including fatal viral infection, with particular susceptibility to herpesviral infections, such as cytomegalovirus, varicella zoster virus, and Epstein-Barr virus. While NKD is rare, studies of these diseases are important for defining specific requirements for human NK cell development and homeostasis. New themes in NK cell biology are emerging through the study of both known and novel NKD, particularly those affecting cell cycle and DNA damage repair, as well as broader PIDs having substantive impact upon NK cells. In addition, the discovery of NKD that affects other innate lymphoid cell (ILC) subsets opens new doors for better understanding the relationship between conventional NK cells and other ILC subsets. Here, we describe the biology underlying human NKD, particularly in the context of new insights into innate immune cell function, including a discussion of recently described NKD with accompanying effects on ILC subsets. Given the impact of these disorders upon human immunity with a common focus upon NK cells, the unifying message of a critical role for NK cells in human host defense singularly emerges.
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Affiliation(s)
- Emily M Mace
- Department of Pediatrics, Columbia University Irving Medical Center, New York, New York
| | - Jordan S Orange
- Department of Pediatrics, Columbia University Irving Medical Center, New York, New York
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10
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Singh B, Bisht KK, Upadhyay U, Kushwaha AC, Nanda JS, Srivastava S, Saini JK, Klar AJS, Singh J. Role of Cdc23/Mcm10 in generating the ribonucleotide imprint at the mat1 locus in fission yeast. Nucleic Acids Res 2019; 47:3422-3433. [PMID: 30759238 PMCID: PMC6468313 DOI: 10.1093/nar/gkz092] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Revised: 01/31/2019] [Accepted: 02/10/2019] [Indexed: 01/28/2023] Open
Abstract
The developmental asymmetry of fission yeast daughter cells derives from inheriting ‘older Watson’ versus ‘older Crick’ DNA strand from the parental cell, strands that are complementary but not identical with each other. A novel DNA strand-specific ‘imprint’, installed during DNA replication at the mating-type locus (mat1), imparts competence for cell type inter-conversion to one of the two chromosome replicas. The catalytic subunit of DNA Polymerase α (Polα) has been implicated in the imprinting process. Based on its known biochemical function, Polα might install the mat1 imprint during lagging strand synthesis. The nature of the imprint is not clear: it is either a nick or a ribonucleotide insertion. Our investigations do not support a direct role of Polα in nicking through putative endonuclease domains but confirm its indirect role in installing an alkali-labile moiety as the imprint. While ruling out the role of the primase subunit of Polα holoenzyme, we find that mutations in the Polα-recruitment and putative primase homology domain in Mcm10/Cdc23 abrogate the ribonucleotide imprint formation. These results, while confirming the ribonucleotide nature of the imprint suggest the possibility of a direct role of Mcm10/Cdc23 in installing it in cooperation with Polα and Swi1.
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Affiliation(s)
- Balveer Singh
- Institute of Genetics and Development of Rennes, Faculte de Medecine, Campus santé de Villejean, 2 avenue du Professor Leon Bernard, CS 34317, 35043 Rennes Cedex, France
| | - Kamlesh K Bisht
- Translational Discovery Biology, (Immuno-Oncology), Bristol-Myers Squibb Route 206 & Province Line Road, Princeton, NJ 08543, USA
| | - Udita Upadhyay
- Department of Anesthesiology, RMSB 8022, 1600 NW, 10th Ave., Miami, FL 33136, USA
| | | | - Jagpreet Singh Nanda
- Department of Pharmacology, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106, USA
| | - Suchita Srivastava
- QC Division, Central Research Institute, Kasauli, Himachal Pradesh 173204, India
| | - Jai Kumar Saini
- Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India
| | - Amar J S Klar
- Gene Regulation and Chromosome Biology Laboratory, National Cancer Institute, Center for Cancer Research, National Institutes of Health, Building 539, Room 154, Frederick, MD 21702-1201, USA
| | - Jagmohan Singh
- Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India
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11
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RNA insertion in DNA as the imprint moiety: the fission yeast paradigm. Curr Genet 2019; 65:1301-1306. [PMID: 31076844 DOI: 10.1007/s00294-019-00991-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 10/26/2022]
Abstract
This review elaborates on the findings of a new report which possibly resolves the biochemical nature of a novel type of DNA imprint as ribonucleotide and the mechanism of its formation during cell differentiation in fission yeast. The process of mating-type switching in fission yeast, Schizosaccharomyces pombe, displays characteristics of a typical mammalian stem cell lineage, wherein a cell divides to produce an identical cell and a differentiated cell after every two cell divisions. This developmental asymmetry has been ascribed to play a role in generation of a DNA strand-specific imprint at the mat1 locus during lagging strand synthesis and its segregation to one of the two daughter cells by the process of asymmetric, semi-conservative DNA replication. The nature of this imprint and mechanisms of its generation have been a subject of research and debate. A recent report by Singh et al. (Nucleic Acids Res 47:3422-3433. https://doi.org/10.1093/nar/gkz092 , 2019) provides compelling evidence in support of a ribonucleotide as the imprint moiety within the mat1 DNA and demonstrates the role of Mcm10/Cdc23, an important, evolutionarily conserved component of DNA replication machinery in eukaryotes, in installing the imprint through a non-canonical primase activity and interaction with DNA Polα and Swi1. The high degree of conservation of DNA replication machinery, especially the presence of the T7 gene 4 helicase/primase domain in the mammalian orthologs of Mcm10 suggests that similar mechanisms of DNA imprinting may play a role during cell differentiation in metazoans.
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12
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Elis S, Desmarchais A, Cardona E, Fouchecourt S, Dalbies-Tran R, Nguyen T, Thermes V, Maillard V, Papillier P, Uzbekova S, Bobe J, Couderc JL, Monget P. Genes Involved in Drosophila melanogaster Ovarian Function Are Highly Conserved Throughout Evolution. Genome Biol Evol 2018; 10:2629-2642. [PMID: 30060195 PMCID: PMC6173279 DOI: 10.1093/gbe/evy158] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2018] [Indexed: 12/11/2022] Open
Abstract
This work presents a systematic approach to study the conservation of genes between fruit flies and mammals. We have listed 971 Drosophila genes involved in female reproduction at the ovarian level and systematically looked for orthologs in the Ciona, zebrafish, coelacanth, lizard, chicken, and mouse. Depending on the species, the percentage of these Drosophila genes with at least one ortholog varies between 69% and 78%. In comparison, only 42% of all the Drosophila genes have an ortholog in the mouse genome (P < 0.0001), suggesting a dramatically higher evolutionary conservation of ovarian genes. The 177 Drosophila genes that have no ortholog in mice and other vertebrates correspond to genes that are involved in mechanisms of oogenesis that are specific to the fruit fly or the insects. Among 759 genes with at least one ortholog in the zebrafish, 73 have an expression enriched in the ovary in this species (RNA-seq data). Among 760 genes that have at least one ortholog in the mouse; 76 and 11 orthologs are reported to be preferentially and exclusively expressed in the mouse ovary, respectively (based on the UniGene expressed sequence tag database). Several of them are already known to play a key role in murine oogenesis and/or to be enriched in the mouse/zebrafish oocyte, whereas others have remained unreported. We have investigated, by RNA-seq and real-time quantitative PCR, the exclusive ovarian expression of 10 genes in fish and mammals. Overall, we have found several novel candidates potentially involved in mammalian oogenesis by an evolutionary approach and using the fruit fly as an animal model.
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Affiliation(s)
- Sebastien Elis
- UMR PRC, CNRS, IFCE, INRA, Université de Tours, Nouzilly, France
| | | | | | | | | | | | | | | | - Pascal Papillier
- UMR PRC, CNRS, IFCE, INRA, Université de Tours, Nouzilly, France
| | | | | | - Jean-Louis Couderc
- GReD Laboratory, Université Clermont Auvergne - CNRS UMR 6293- INSERM U1103, Clermont-Ferrand, France
| | - Philippe Monget
- UMR PRC, CNRS, IFCE, INRA, Université de Tours, Nouzilly, France
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13
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Mcm10: A Dynamic Scaffold at Eukaryotic Replication Forks. Genes (Basel) 2017; 8:genes8020073. [PMID: 28218679 PMCID: PMC5333062 DOI: 10.3390/genes8020073] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 02/09/2017] [Accepted: 02/09/2017] [Indexed: 12/13/2022] Open
Abstract
To complete the duplication of large genomes efficiently, mechanisms have evolved that coordinate DNA unwinding with DNA synthesis and provide quality control measures prior to cell division. Minichromosome maintenance protein 10 (Mcm10) is a conserved component of the eukaryotic replisome that contributes to this process in multiple ways. Mcm10 promotes the initiation of DNA replication through direct interactions with the cell division cycle 45 (Cdc45)-minichromosome maintenance complex proteins 2-7 (Mcm2-7)-go-ichi-ni-san GINS complex proteins, as well as single- and double-stranded DNA. After origin firing, Mcm10 controls replication fork stability to support elongation, primarily facilitating Okazaki fragment synthesis through recruitment of DNA polymerase-α and proliferating cell nuclear antigen. Based on its multivalent properties, Mcm10 serves as an essential scaffold to promote DNA replication and guard against replication stress. Under pathological conditions, Mcm10 is often dysregulated. Genetic amplification and/or overexpression of MCM10 are common in cancer, and can serve as a strong prognostic marker of poor survival. These findings are compatible with a heightened requirement for Mcm10 in transformed cells to overcome limitations for DNA replication dictated by altered cell cycle control. In this review, we highlight advances in our understanding of when, where and how Mcm10 functions within the replisome to protect against barriers that cause incomplete replication.
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Wei X, Xiaoling Z, Kai M, Rui W, Jing X, Min G, Zhonghong W, Jianhui T, Xinyu Z, Lei A. Characterization and comparative analyses of transcriptomes for in vivo and in vitro produced peri-implantation conceptuses and endometria from sheep. J Reprod Dev 2016; 62:279-87. [PMID: 26946921 PMCID: PMC4919292 DOI: 10.1262/jrd.2015-064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
An increasing number of reports indicate that in vitro fertilization (IVF) is highly
associated with long‑term side effects on embryonic and postnatal development, and can sometimes result in
embryonic implant failure. While high‑throughput gene expression analysis has been used to explore the
mechanisms underlying IVF-induced side effects on embryonic development, little is known about the effects of
IVF on conceptus–endometrial interactions during the peri-implantation period. Using sheep as a model, we
performed a comparative transcriptome analysis between in vivo (IVO; in vivo
fertilized followed by further development in the uterus) and in vitro produced (IVP; IVF
with further culture in the incubator) conceptuses, and the caruncular and intercaruncular areas of the ovine
endometrium. We identified several genes that were differentially expressed between the IVO and IVP groups on
day 17, when adhesion between the trophoblast and the uterine luminal epithelium begins in sheep. By
performing Gene Ontology enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway
analysis, we found that, in the conceptus, differentially expressed genes (DEGs) were associated mainly with
functions relating to cell binding and the cell cycle. In the endometrial caruncular area, DEGs were involved
in cell adhesion/migration and apoptosis, and in the intercaruncular area, they were significantly enriched in
pathways of signal transduction and transport. Thus, these DEGs are potential candidates for further exploring
the mechanism underlying IVF/IVP-induced embryonic implant failure that occurs due to a loss of interaction
between the conceptus and endometrium during the peri-implantation period.
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Affiliation(s)
- Xia Wei
- Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture, College of Animal Sciences and Technology, China Agricultural University, Beijing 100094, P. R. China
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15
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Reubens MC, Biller MD, Bedsole SE, Hopkins LT, Ables ET, Christensen TW. Mcm10 is required for oogenesis and early embryogenesis in Drosophila. Mech Dev 2015; 138 Pt 3:291-9. [PMID: 26369283 DOI: 10.1016/j.mod.2015.09.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 08/27/2015] [Accepted: 09/08/2015] [Indexed: 01/05/2023]
Abstract
Efficient replication of the genome and the establishment of endogenous chromatin states are processes that are essential to eukaryotic life. It is well documented that Mcm10 is intimately linked to both of these important biological processes; therefore, it is not surprising that Mcm10 is commonly misregulated in many human cancers. Most of the research regarding the biological roles of Mcm10 has been performed in single-cell or cell-free in-vitro systems. Though these systems are informative, they are unable to provide information on the cell-specific function of Mcm10 in the context of the tissue and organ systems that comprise multicellular eukaryotes. We therefore sought to identify the potential biological functions of Mcm10 in the context of a complex multicellular organism by continuing our analysis in Drosophila using three novel hypomorphic alleles. Observation of embryonic nuclear morphology and quantification of embryo hatch rates reveal that maternal loading of Mcm10 is required for embryonic nuclear stability, and suggest a role for Mcm10 post zygotic transition. Contrary to the essential nature of Mcm10 depicted in the literature, it does not appear to be required for adult viability in Drosophila if embryonic requirements are met. Although not required for adult somatic viability, analysis of fecundity and ovarian morphology in mutant females suggest that Mcm10 plays a role in maintenance of the female germline. Taken together, our results demonstrate critical roles for Mcm10 during early embryogenesis, and mark the first data linking Mcm10 to female specific reproduction in multicellular eukaryotes.
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Affiliation(s)
- Michael C Reubens
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Megan D Biller
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Sidney E Bedsole
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Lucas T Hopkins
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Elizabeth T Ables
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
| | - Tim W Christensen
- Department of Biology, East Carolina University, Greenville, NC 27878, USA.
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16
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Fang X, Netzer M, Baumgartner C, Bai C, Wang X. Genetic network and gene set enrichment analysis to identify biomarkers related to cigarette smoking and lung cancer. Cancer Treat Rev 2012; 39:77-88. [PMID: 22789435 DOI: 10.1016/j.ctrv.2012.06.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 06/03/2012] [Accepted: 06/06/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVES Cigarette smoking is the most demonstrated risk factor for the development of lung cancer, while the related genetic mechanisms are still unclear. METHODS The preprocessed microarray expression dataset was downloaded from Gene Expression Omnibus database. Samples were classified according to the disease state, stage and smoking state. A new computational strategy was applied for the identification and biological interpretation of new candidate genes in lung cancer and smoking by coupling a network-based approach with gene set enrichment analysis. MEASUREMENTS Network analysis was performed by pair-wise comparison according to the disease states (tumor or normal), smoking states (current smokers or nonsmokers or former smokers), or the disease stage (stages I-IV). The most activated metabolic pathways were identified by gene set enrichment analysis. RESULTS Panels of top ranked gene candidates in smoking or cancer development were identified, including genes involved in cell proliferation and drug metabolism like cytochrome P450 and WW domain containing transcription regulator 1. Semaphorin 5A and protein phosphatase 1F are the common genes represented as major hubs in both the smoking and cancer related network. Six pathways, e.g. cell cycle, DNA replication, RNA transport, protein processing in endoplasmic reticulum, vascular smooth muscle contraction and endocytosis were commonly involved in smoking and lung cancer when comparing the top ten selected pathways. CONCLUSION New approach of bioinformatics for biomarker identification and validation can probe into deep genetic relationships between cigarette smoking and lung cancer. Our studies indicate that disease-specific network biomarkers, interaction between genes/proteins, or cross-talking of pathways provide more specific values for the development of precision therapies for lung.
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Affiliation(s)
- Xiaocong Fang
- Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, Shanghai, China.
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17
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Mcm10 associates with the loaded DNA helicase at replication origins and defines a novel step in its activation. EMBO J 2012; 31:2195-206. [PMID: 22433841 DOI: 10.1038/emboj.2012.69] [Citation(s) in RCA: 103] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 02/28/2012] [Indexed: 12/13/2022] Open
Abstract
Mcm10 is essential for chromosome replication in eukaryotic cells and was previously thought to link the Mcm2-7 DNA helicase at replication forks to DNA polymerase alpha. Here, we show that yeast Mcm10 interacts preferentially with the fraction of the Mcm2-7 helicase that is loaded in an inactive form at origins of DNA replication, suggesting a role for Mcm10 during the initiation of chromosome replication, but Mcm10 is not a stable component of the replisome subsequently. Studies with budding yeast and human cells indicated that Mcm10 chaperones the catalytic subunit of polymerase alpha and preserves its stability. We used a novel degron allele to inactivate Mcm10 efficiently and this blocked the initiation of chromosome replication without causing degradation of DNA polymerase alpha. Strikingly, the other essential helicase subunits Cdc45 and GINS were still recruited to Mcm2-7 when cells entered S-phase without Mcm10, but origin unwinding was blocked. These findings indicate that Mcm10 is required for a novel step during activation of the Cdc45-MCM-GINS helicase at DNA replication origins.
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