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Wen C, Cao L, Wang S, Xu W, Yu Y, Zhao S, Yang F, Chen ZJ, Zhao S, Yang Y, Qin Y. MCM8 interacts with DDX5 to promote R-loop resolution. EMBO J 2024; 43:3044-3071. [PMID: 38858601 PMCID: PMC11251167 DOI: 10.1038/s44318-024-00134-0] [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: 08/12/2023] [Revised: 05/17/2024] [Accepted: 05/21/2024] [Indexed: 06/12/2024] Open
Abstract
MCM8 has emerged as a core gene in reproductive aging and is crucial for meiotic homologous recombination repair. It also safeguards genome stability by coordinating the replication stress response during mitosis, but its function in mitotic germ cells remains elusive. Here we found that disabling MCM8 in mice resulted in proliferation defects of primordial germ cells (PGCs) and ultimately impaired fertility. We further demonstrated that MCM8 interacted with two known helicases DDX5 and DHX9, and loss of MCM8 led to R-loop accumulation by reducing the retention of these helicases at R-loops, thus inducing genome instability. Cells expressing premature ovarian insufficiency-causative mutants of MCM8 with decreased interaction with DDX5 displayed increased R-loop levels. These results show MCM8 interacts with R-loop-resolving factors to prevent R-loop-induced DNA damage, which may contribute to the maintenance of genome integrity of PGCs and reproductive reserve establishment. Our findings thus reveal an essential role for MCM8 in PGC development and improve our understanding of reproductive aging caused by genome instability in mitotic germ cells.
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Affiliation(s)
- Canxin Wen
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Lili Cao
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Shuhan Wang
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Weiwei Xu
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Yongze Yu
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Simin Zhao
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
| | - Fan Yang
- Advanced Medical Research Institute, Meili Lake Translational Research Park, Cheeloo College of Medicine, Shandong University, Jinan, China
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, 250012, China
| | - Zi-Jiang Chen
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
- Department of Reproductive Medicine, Ren Ji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shidou Zhao
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China.
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China.
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China.
| | - Yajuan Yang
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China.
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China.
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China.
| | - Yingying Qin
- State Key Laboratory of Reproductive Medicine and Offspring Health, Center for Reproductive Medicine, Institute of Women, Children and Reproductive Health, Shandong University, Jinan, Shandong, 250012, China.
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China.
- Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, Shandong, 250012, China.
- Shandong Technology Innovation Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.
- Shandong Key Laboratory of Reproductive Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250012, China.
- Research Unit of Gametogenesis and Health of ART-Offspring, Chinese Academy of Medical Sciences (No.2021RU001), Jinan, Shandong, 250012, China.
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2
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Arter M, Keeney S. Divergence and conservation of the meiotic recombination machinery. Nat Rev Genet 2024; 25:309-325. [PMID: 38036793 DOI: 10.1038/s41576-023-00669-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2023] [Indexed: 12/02/2023]
Abstract
Sexually reproducing eukaryotes use recombination between homologous chromosomes to promote chromosome segregation during meiosis. Meiotic recombination is almost universally conserved in its broad strokes, but specific molecular details often differ considerably between taxa, and the proteins that constitute the recombination machinery show substantial sequence variability. The extent of this variation is becoming increasingly clear because of recent increases in genomic resources and advances in protein structure prediction. We discuss the tension between functional conservation and rapid evolutionary change with a focus on the proteins that are required for the formation and repair of meiotic DNA double-strand breaks. We highlight phylogenetic relationships on different time scales and propose that this remarkable evolutionary plasticity is a fundamental property of meiotic recombination that shapes our understanding of molecular mechanisms in reproductive biology.
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Affiliation(s)
- Meret Arter
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Scott Keeney
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
- Howard Hughes Medical Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
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3
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Acharya A, Bret H, Huang JW, Mütze M, Göse M, Kissling VM, Seidel R, Ciccia A, Guérois R, Cejka P. Mechanism of DNA unwinding by MCM8-9 in complex with HROB. Nat Commun 2024; 15:3584. [PMID: 38678026 PMCID: PMC11055865 DOI: 10.1038/s41467-024-47936-8] [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: 06/16/2023] [Accepted: 04/15/2024] [Indexed: 04/29/2024] Open
Abstract
HROB promotes the MCM8-9 helicase in DNA damage response. To understand how HROB activates MCM8-9, we defined their interaction interface. We showed that HROB makes important yet transient contacts with both MCM8 and MCM9, and binds the MCM8-9 heterodimer with the highest affinity. MCM8-9-HROB prefer branched DNA structures, and display low DNA unwinding processivity. MCM8-9 unwinds DNA as a hexamer that assembles from dimers on DNA in the presence of ATP. The hexamer involves two repeating protein-protein interfaces between the alternating MCM8 and MCM9 subunits. One of these interfaces is quite stable and forms an obligate heterodimer across which HROB binds. The other interface is labile and mediates hexamer assembly, independently of HROB. The ATPase site formed at the labile interface contributes disproportionally more to DNA unwinding than that at the stable interface. Here, we show that HROB promotes DNA unwinding downstream of MCM8-9 loading and ring formation on ssDNA.
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Affiliation(s)
- Ananya Acharya
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, 6500, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, 8093, Switzerland
| | - Hélène Bret
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France
| | - Jen-Wei Huang
- Department of Genetics and Development, Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Martin Mütze
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Martin Göse
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Vera Maria Kissling
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, 8093, Switzerland
- Particles-Biology Interactions Laboratory, Department of Materials Meet Life, Swiss Federal Laboratories for Materials Science and Technology (Empa), St. Gallen, 9014, Switzerland
| | - Ralf Seidel
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Alberto Ciccia
- Department of Genetics and Development, Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Raphaël Guérois
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-sur-Yvette, France.
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, 6500, Switzerland.
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, 8093, Switzerland.
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4
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Acharya A, Bret H, Huang JW, Mütze M, Göse M, Kissling V, Seidel R, Ciccia A, Guérois R, Cejka P. Mechanism of DNA unwinding by hexameric MCM8-9 in complex with HROB. RESEARCH SQUARE 2023:rs.3.rs-3054483. [PMID: 37461676 PMCID: PMC10350107 DOI: 10.21203/rs.3.rs-3054483/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
The human MCM8-9 helicase functions in concert with HROB in the context of homologous recombination, but its precise function is unknown. To gain insights into how HROB regulates MCM8-9, we first used molecular modeling and biochemistry to define their interaction interface. We show that HROB makes important contacts with both MCM8 and MCM9 subunits, which directly promotes its DNA-dependent ATPase and helicase activities. MCM8-9-HROB preferentially binds and unwinds branched DNA structures, and single-molecule experiments reveal a low DNA unwinding processivity. MCM8-9 unwinds DNA as a hexameric complex that assembles from dimers on DNA in the presence of ATP, which is prerequisite for its helicase function. The hexamer formation thus involves two repeating protein-protein interfaces forming between the alternating MCM8 and MCM9 subunits. One of these interfaces is rather stable and forms an obligate heterodimer, while the other interface is labile and mediates the assembly of the hexamer on DNA, independently of HROB. The ATPase site composed of the subunits forming the labile interface disproportionally contributes to DNA unwinding. HROB does not affect the MCM8-9 ring formation, but promotes DNA unwinding downstream by possibly coordinating ATP hydrolysis with structural transitions accompanying translocation of MCM8-9 on DNA.
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Affiliation(s)
- Ananya Acharya
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, 6500, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, 8093, Switzerland
| | - Hélène Bret
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l’Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, 91190, France
| | - Jen-Wei Huang
- Department of Genetics and Development, Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Martin Mütze
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Martin Göse
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Vera Kissling
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, 8093, Switzerland
| | - Ralf Seidel
- Peter Debye Institute for Soft Matter Physics, Universität Leipzig, Leipzig, 04103, Germany
| | - Alberto Ciccia
- Department of Genetics and Development, Institute for Cancer Genetics, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l’Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, 91190, France
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, 6500, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, 8093, Switzerland
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Helderman NC, Terlouw D, Bonjoch L, Golubicki M, Antelo M, Morreau H, van Wezel T, Castellví-Bel S, Goldberg Y, Nielsen M. Molecular functions of MCM8 and MCM9 and their associated pathologies. iScience 2023; 26:106737. [PMID: 37378315 PMCID: PMC10291252 DOI: 10.1016/j.isci.2023.106737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2023] Open
Abstract
Minichromosome Maintenance 8 Homologous Recombination Repair Factor (MCM8) and Minichromosome Maintenance 9 Homologous Recombination Repair Factor (MCM9) are recently discovered minichromosome maintenance proteins and are implicated in multiple DNA-related processes and pathologies, including DNA replication (initiation), meiosis, homologous recombination and mismatch repair. Consistent with these molecular functions, variants of MCM8/MCM9 may predispose carriers to disorders such as infertility and cancer and should therefore be included in relevant diagnostic testing. In this overview of the (patho)physiological functions of MCM8 and MCM9 and the phenotype of MCM8/MCM9 variant carriers, we explore the potential clinical implications of MCM8/MCM9 variant carriership and highlight important future directions of MCM8 and MCM9 research. With this review, we hope to contribute to better MCM8/MCM9 variant carrier management and the potential utilization of MCM8 and MCM9 in other facets of scientific research and medical care.
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Affiliation(s)
| | - Diantha Terlouw
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
- Department of Pathology, Leiden University Medical Center, Leiden, the Netherlands
| | - Laia Bonjoch
- Gastroenterology Department, Institut d’Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Mariano Golubicki
- Oncology Section and Molecular Biology Laboratory, Hospital of Gastroenterology "Dr. C.B. Udaondo", Buenos Aires, Argentina
| | - Marina Antelo
- Oncology Section and Molecular Biology Laboratory, Hospital of Gastroenterology "Dr. C.B. Udaondo", Buenos Aires, Argentina
| | - Hans Morreau
- Department of Pathology, Leiden University Medical Center, Leiden, the Netherlands
| | - Tom van Wezel
- Department of Pathology, Leiden University Medical Center, Leiden, the Netherlands
| | - Sergi Castellví-Bel
- Gastroenterology Department, Institut d’Investigacions Biomèdiques August Pi I Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBEREHD), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
| | - Yael Goldberg
- Raphael Recanati Genetic Institute, Rabin Medical Center-Beilinson Hospital, Petah Tikva, Israel
| | - Maartje Nielsen
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, the Netherlands
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Acharya A, Bret H, Huang JW, Mütze M, Göse M, Kissling V, Seidel R, Ciccia A, Guérois R, Cejka P. Mechanism of DNA unwinding by hexameric MCM8-9 in complex with HROB. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.12.544631. [PMID: 37398313 PMCID: PMC10312610 DOI: 10.1101/2023.06.12.544631] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
The human MCM8-9 helicase functions in concert with HROB in the context of homologous recombination, but its precise function is unknown. To gain insights into how HROB regulates MCM8-9, we first used molecular modeling and biochemistry to define their interaction interface. We show that HROB makes important contacts with both MCM8 and MCM9 subunits, which directly promotes its DNA-dependent ATPase and helicase activities. MCM8-9-HROB preferentially binds and unwinds branched DNA structures, and single-molecule experiments reveal a low DNA unwinding processivity. MCM8-9 unwinds DNA as a hexameric complex that assembles from dimers on DNA in the presence of ATP, which is prerequisite for its helicase function. The hexamer formation thus involves two repeating protein-protein interfaces forming between the alternating MCM8 and MCM9 subunits. One of these interfaces is rather stable and forms an obligate heterodimer, while the other interface is labile and mediates the assembly of the hexamer on DNA, independently of HROB. The ATPase site composed of the subunits forming the labile interface disproportionally contributes to DNA unwinding. HROB does not affect the MCM8-9 ring formation, but promotes DNA unwinding downstream by possibly coordinating ATP hydrolysis with structural transitions accompanying translocation of MCM8-9 on DNA.
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7
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Klucnika A, Mu P, Jezek J, McCormack M, Di Y, Bradshaw CR, Ma H. REC drives recombination to repair double-strand breaks in animal mtDNA. J Cell Biol 2023; 222:e202201137. [PMID: 36355348 PMCID: PMC9652705 DOI: 10.1083/jcb.202201137] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 09/09/2022] [Accepted: 10/19/2022] [Indexed: 11/11/2022] Open
Abstract
Mechanisms that safeguard mitochondrial DNA (mtDNA) limit the accumulation of mutations linked to mitochondrial and age-related diseases. Yet, pathways that repair double-strand breaks (DSBs) in animal mitochondria are poorly understood. By performing a candidate screen for mtDNA repair proteins, we identify that REC-an MCM helicase that drives meiotic recombination in the nucleus-also localizes to mitochondria in Drosophila. We show that REC repairs mtDNA DSBs by homologous recombination in somatic and germline tissues. Moreover, REC prevents age-associated mtDNA mutations. We further show that MCM8, the human ortholog of REC, also localizes to mitochondria and limits the accumulation of mtDNA mutations. This study provides mechanistic insight into animal mtDNA recombination and demonstrates its importance in safeguarding mtDNA during ageing and evolution.
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Affiliation(s)
- Anna Klucnika
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Peiqiang Mu
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, South China Agricultural University, Guangzhou, Guangdong, China
| | - Jan Jezek
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Matthew McCormack
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Ying Di
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
| | | | - Hansong Ma
- Wellcome/Cancer Research UK Gurdon Institute, Cambridge, UK
- Department of Genetics, University of Cambridge, Cambridge, UK
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8
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Hatkevich T, Miller DE, Turcotte CA, Miller MC, Sekelsky J. A pathway for error-free non-homologous end joining of resected meiotic double-strand breaks. Nucleic Acids Res 2021; 49:879-890. [PMID: 33406239 PMCID: PMC7826270 DOI: 10.1093/nar/gkaa1205] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 11/22/2020] [Accepted: 11/25/2020] [Indexed: 12/31/2022] Open
Abstract
Programmed DNA double-strand breaks (DSBs) made during meiosis are repaired by recombination with the homologous chromosome to generate, at selected sites, reciprocal crossovers that are critical for the proper separation of homologs in the first meiotic division. Backup repair processes can compensate when the normal meiotic recombination processes are non-functional. We describe a novel backup repair mechanism that occurs when the homologous chromosome is not available in Drosophila melanogaster meiosis. In the presence of a previously described mutation (Mcm5A7) that disrupts chromosome pairing, DSB repair is initiated by homologous recombination but is completed by non-homologous end joining (NHEJ). Remarkably, this process yields precise repair products. Our results provide support for a recombination intermediate recently proposed in mouse meiosis, in which an oligonucleotide bound to the Spo11 protein that catalyzes DSB formation remains bound after resection. We propose that this oligonucleotide functions as a primer for fill-in synthesis to allow scarless repair by NHEJ. We argue that this is a conserved repair mechanism that is likely to be invoked to overcome occasional challenges in normal meiosis.
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Affiliation(s)
- Talia Hatkevich
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Danny E Miller
- Department of Pediatrics, Division of Medical Genetics, University of Washington, Seattle, Washington and Seattle Children's Hospital, Seattle, WA 98105, USA
| | - Carolyn A Turcotte
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Margaret C Miller
- Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599, USA
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599, USA.,Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599, USA.,Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599, USA
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9
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Comparative genomic analysis reveals evolutionary and structural attributes of MCM gene family in Arabidopsis thaliana and Oryza sativa. J Biotechnol 2020; 327:117-132. [PMID: 33373625 DOI: 10.1016/j.jbiotec.2020.12.010] [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: 08/15/2020] [Revised: 11/16/2020] [Accepted: 12/17/2020] [Indexed: 11/20/2022]
Abstract
The mini-chromosome maintenance (MCM) family, a large and functionally diverse protein family belonging to the AAA+ superfamily, is essential for DNA replication in all eukaryotic organisms. The MCM 2-7 form a hetero-hexameric complex which serves as licensing factor necessary to ensure the proper genomic DNA replication during the S phase of cell cycle. MCM 8-10 are also associated with the DNA replication process though their roles are particularly unclear. In this study, we report an extensive in silico analysis of MCM gene family (MCM 2-10) in Arabidopsis and rice. Comparative analysis of genomic distribution across eukaryotes revealed conservation of core MCMs 2-7 while MCMs 8-10 are absent in some taxa. Domain architecture analysis underlined MCM 2-10 subfamily specific features. Phylogenetic analyses clustered MCMs into 9 clades as per their subfamily. Duplication events are prominent in plant MCM family, however no duplications are observed in Arabidopsis and rice MCMs. Synteny analysis among Arabidopsis thaliana, Oryza sativa, Glycine max and Zea mays MCMs demonstrated orthologous relationships and duplication events. Further, estimation of synonymous and non-synonymous substitution rates illustrated evolution of MCM family under strong constraints. Expression profiling using available microarray data and qRT-PCR revealed differential expression under various stress conditions, hinting at their potential use to develop stress resilient crops. Homology modeling of Arabidopsis and rice MCM 2-7 and detailed comparison with yeast MCMs identified conservation of eukaryotic specific insertions and extensions as compared to archeal MCMs. Protein-protein interaction analysis revealed an extensive network of putative interacting partners mainly involved in DNA replication and repair. The present study provides novel insights into the MCM family in Arabidopsis and rice and identifies unique features, thus opening new perspectives for further targeted analyses.
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10
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Tian M, Loidl J. An MCM family protein promotes interhomolog recombination by preventing precocious intersister repair of meiotic DSBs. PLoS Genet 2019; 15:e1008514. [PMID: 31815942 PMCID: PMC6922451 DOI: 10.1371/journal.pgen.1008514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 12/19/2019] [Accepted: 11/11/2019] [Indexed: 12/02/2022] Open
Abstract
Recombinational repair of meiotic DNA double-strand breaks (DSBs) uses the homologous chromosome as a template, although the sister chromatid offers itself as a spatially more convenient substrate. In many organisms, this choice is reinforced by the recombination protein Dmc1. In Tetrahymena, the repair of DSBs, which are formed early in prophase, is postponed to late prophase when homologous chromosomes and sister chromatids become juxtaposed owing to tight parallel packing in the thread-shaped nucleus, and thus become equally suitable for use as repair templates. The delay in DSB repair is achieved by rejection of the invading strand by the Sgs1 helicase in early meiotic prophase. In the absence of Mcmd1, a meiosis-specific minichromosome maintenance (MCM)-like protein (and its partner Pamd1), Dmc1 is prematurely lost from chromatin and DNA synthesis (as monitored by BrdU incorporation) takes place in early prophase. In mcmd1Δ and pamd1Δ mutants, only a few crossovers are formed. In a mcmd1Δ hop2Δ double mutant, normal timing of Dmc1 loss and DNA synthesis is restored. Because Tetrahymena Hop2 is believed to enable homologous strand invasion, we conclude that Dmc1 loss in the absence of Mcmd1 affects only post-invasion recombination intermediates. Therefore, we propose that the Dmc1 nucleofilament becomes dismantled immediately after forming a heteroduplex with a template strand. As a consequence, repair synthesis and D-loop extension starts in early prophase intermediates and prevents strand rejection before the completion of homologous pairing. In this case, DSB repair may primarily use the sister chromatid. We conclude that Mcmd1‒Pamd1 protects the Dmc1 nucleofilament from premature dismantling, thereby suppressing precocious repair synthesis and excessive intersister strand exchange at the cost of homologous recombination. Minichromosome maintenance (MCM) proteins are mainly known for their involvement in DNA replication. However, distant members of this protein family have recently been shown to promote interhomolog over intersister recombination in meiosis. They achieve this by enforcing or stabilizing the invasion of a double-stranded DNA by a filament consisting of a homologous single-stranded DNA molecule coated with a strand exchange protein. This interaction then would lead to the exchange of DNA strands and, ultimately, crossing over. Here, we study a member of the MCM protein family in the protist Tetrahymena thermophila. Meiosis in this organism has several unusual features: A synaptonemal complex is not formed, and homologous prealignment occurs during the close parallel arrangement of chromosomes in the extremely elongated, threadlike meiotic prophase nucleus. This noncanonical pairing has come along with altered mechanisms for recombination partner choice. Thus, we find that the Tetrahymena meiotic MCM protein promotes crossovers in an unprecedented way: It suppresses the formation of recombination intermediates between sister DNA molecules early in meiosis, thereby increasing the chance of competing interhomolog recombination events. Thus, members of the same protein family have been harnessed by different organisms to achieve the same result via completely different mechanisms.
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Affiliation(s)
- Miao Tian
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Josef Loidl
- Department of Chromosome Biology, Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
- * E-mail:
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11
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Hustedt N, Saito Y, Zimmermann M, Álvarez-Quilón A, Setiaputra D, Adam S, McEwan A, Yuan JY, Olivieri M, Zhao Y, Kanemaki MT, Jurisicova A, Durocher D. Control of homologous recombination by the HROB-MCM8-MCM9 pathway. Genes Dev 2019; 33:1397-1415. [PMID: 31467087 PMCID: PMC6771392 DOI: 10.1101/gad.329508.119] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 08/08/2019] [Indexed: 12/17/2022]
Abstract
In this study, Hustedt et al. use CRISPR-based genetic screens to build a clear picture of the postsynaptic steps of homologous recombination in mammalian cells. They report the identification of C17orf53/HROB, a factor required for cell survival after exposure to a variety of replication stress-inducing genotoxins and for the resolution but not formation of Rad51 foci. DNA repair by homologous recombination (HR) is essential for genomic integrity, tumor suppression, and the formation of gametes. HR uses DNA synthesis to repair lesions such as DNA double-strand breaks and stalled DNA replication forks, but despite having a good understanding of the steps leading to homology search and strand invasion, we know much less of the mechanisms that establish recombination-associated DNA polymerization. Here, we report that C17orf53/HROB is an OB-fold-containing factor involved in HR that acts by recruiting the MCM8–MCM9 helicase to sites of DNA damage to promote DNA synthesis. Mice with targeted mutations in Hrob are infertile due to depletion of germ cells and display phenotypes consistent with a prophase I meiotic arrest. The HROB–MCM8–MCM9 pathway acts redundantly with the HELQ helicase, and cells lacking both HROB and HELQ have severely impaired HR, suggesting that they underpin two major routes for the completion of HR downstream from RAD51. The function of HROB in HR is reminiscent of that of gp59, which acts as the replicative helicase loader during bacteriophage T4 recombination-dependent DNA replication. We therefore propose that the loading of MCM8–MCM9 by HROB may similarly be a key step in the establishment of mammalian recombination-associated DNA synthesis.
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Affiliation(s)
- Nicole Hustedt
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Yuichiro Saito
- Department of Chromosome Science, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Michal Zimmermann
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | | | - Dheva Setiaputra
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Salomé Adam
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Andrea McEwan
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Jing Yi Yuan
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada
| | - Michele Olivieri
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Yichao Zhao
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Masato T Kanemaki
- Department of Chromosome Science, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
| | - Andrea Jurisicova
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada.,Department of Obstetrics and Gynecology, University of Toronto, Toronto, Ontario M5G 0D8, Canada
| | - Daniel Durocher
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario M5G 1X5, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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12
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Cirri E, De Decker S, Bilcke G, Werner M, Osuna-Cruz CM, De Veylder L, Vandepoele K, Werz O, Vyverman W, Pohnert G. Associated Bacteria Affect Sexual Reproduction by Altering Gene Expression and Metabolic Processes in a Biofilm Inhabiting Diatom. Front Microbiol 2019; 10:1790. [PMID: 31428077 PMCID: PMC6688387 DOI: 10.3389/fmicb.2019.01790] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/19/2019] [Indexed: 01/23/2023] Open
Abstract
Diatoms are unicellular algae with a fundamental role in global biogeochemical cycles as major primary producers at the base of aquatic food webs. In recent years, chemical communication between diatoms and associated bacteria has emerged as a key factor in diatom ecology, spurred by conceptual and technological advancements to study the mechanisms underlying these interactions. Here, we use a combination of physiological, transcriptomic, and metabolomic approaches to study the influence of naturally co-existing bacteria, Maribacter sp. and Roseovarius sp., on the sexual reproduction of the biofilm inhabiting marine pennate diatom Seminavis robusta. While Maribacter sp. severely reduces the reproductive success of S. robusta cultures, Roseovarius sp. slightly enhances it. Contrary to our expectation, we demonstrate that the effect of the bacterial exudates is not caused by altered cell-cycle regulation prior to the switch to meiosis. Instead, Maribacter sp. exudates cause a reduced production of diproline, the sexual attraction pheromone of S. robusta. Transcriptomic analyses show that this is likely an indirect consequence of altered intracellular metabolic fluxes in the diatom, especially those related to amino acid biosynthesis, oxidative stress response, and biosynthesis of defense molecules. This study provides the first insights into the influence of bacteria on diatom sexual reproduction and adds a new dimension to the complexity of a still understudied phenomenon in natural diatom populations.
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Affiliation(s)
- Emilio Cirri
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Jena, Germany
| | - Sam De Decker
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
| | - Gust Bilcke
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Markus Werner
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University Jena, Jena, Germany
| | - Cristina Maria Osuna-Cruz
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Lieven De Veylder
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Klaas Vandepoele
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Oliver Werz
- Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmacy, Friedrich-Schiller-University Jena, Jena, Germany
| | - Wim Vyverman
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium
| | - Georg Pohnert
- Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Jena, Germany
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13
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Meiotic MCM Proteins Promote and Inhibit Crossovers During Meiotic Recombination. Genetics 2019; 212:461-468. [PMID: 31028111 PMCID: PMC6553819 DOI: 10.1534/genetics.119.302221] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 04/22/2019] [Indexed: 01/29/2023] Open
Abstract
Crossover formation as a result of meiotic recombination is vital for the proper segregation of homologous chromosomes at the end of meiosis I. In many organisms, crossovers are generated through two crossover pathways: Class I and Class II. To ensure accurate crossover formation, meiosis-specific protein complexes regulate the degree to which each pathway is used. One such complex is the mei-mini-chromosome maintenance (MCM) complex, which contains MCM and MCM-like proteins REC (ortholog of Mcm8), MEI-217, and MEI-218. The mei-MCM complex genetically promotes Class I crossovers and inhibits Class II crossovers in Drosophila, but it is unclear how individual mei-MCM proteins contribute to crossover regulation. In this study, we perform genetic analyses to understand how specific regions and motifs of mei-MCM proteins contribute to Class I and II crossover formation, and distribution. Our analyses show that the long, disordered N-terminus of MEI-218 is dispensable for crossover formation, and that mutations that disrupt REC’s Walker A and B motifs differentially affect Class I and Class II crossover formation. In rec Walker A mutants, Class I crossovers exhibit no change but Class II crossovers are increased. However, in rec Walker B mutants, Class I crossovers are severely impaired and Class II crossovers are increased. These results suggest that REC may form multiple complexes that exhibit differential REC-dependent ATP-binding and -hydrolyzing requirements. These results provide genetic insight into the mechanisms through which mei-MCM proteins promote Class I crossovers and inhibit Class II crossovers.
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14
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Griffin WC, Trakselis MA. The MCM8/9 complex: A recent recruit to the roster of helicases involved in genome maintenance. DNA Repair (Amst) 2019; 76:1-10. [PMID: 30743181 DOI: 10.1016/j.dnarep.2019.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/03/2019] [Indexed: 12/11/2022]
Abstract
There are several DNA helicases involved in seemingly overlapping aspects of homologous and homoeologous recombination. Mutations of many of these helicases are directly implicated in genetic diseases including cancer, rapid aging, and infertility. MCM8/9 are recent additions to the catalog of helicases involved in recombination, and so far, the evidence is sparse, making assignment of function difficult. Mutations in MCM8/9 correlate principally with primary ovarian failure/insufficiency (POF/POI) and infertility indicating a meiotic defect. However, they also act when replication forks collapse/break shuttling products into mitotic recombination and several mutations are found in various somatic cancers. This review puts MCM8/9 in context with other replication and recombination helicases to narrow down its genomic maintenance role. We discuss the known structure/function relationship, the mutational spectrum, and dissect the available cellular and organismal data to better define its role in recombination.
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Affiliation(s)
- Wezley C Griffin
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA.
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15
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Korunes KL, Noor MAF. Pervasive gene conversion in chromosomal inversion heterozygotes. Mol Ecol 2018; 28:1302-1315. [PMID: 30387889 DOI: 10.1111/mec.14921] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/27/2018] [Accepted: 10/22/2018] [Indexed: 12/30/2022]
Abstract
Chromosomal inversions shape recombination landscapes, and species differing by inversions may exhibit reduced gene flow in these regions of the genome. Though single crossovers within inversions are not usually recovered from inversion heterozygotes, the recombination barrier imposed by inversions is nuanced by noncrossover gene conversion. Here, we provide a genomewide empirical analysis of gene conversion rates both within species and in species hybrids. We estimate that gene conversion occurs at a rate of 1 × 10-5 to 2.5 × 10-5 converted sites per bp per generation in experimental crosses within Drosophila pseudoobscura and between D. pseudoobscura and its naturally hybridizing sister species D. persimilis. This analysis is the first direct empirical assessment of gene conversion rates within inversions of a species hybrid. Our data show that gene conversion rates in interspecies hybrids are at least as high as within-species estimates of gene conversion rates, and gene conversion occurs regularly within and around inverted regions of species hybrids, even near inversion breakpoints. We also found that several gene conversion events appeared to be mitotic rather than meiotic in origin. Finally, we observed that gene conversion rates are higher in regions of lower local sequence divergence, yet our observed gene conversion rates in more divergent inverted regions were at least as high as in less divergent collinear regions. Given our observed high rates of gene conversion despite the sequence differentiation between species, especially in inverted regions, gene conversion has the potential to reduce the efficacy of inversions as barriers to recombination over evolutionary time.
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16
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Lahiri S, Li Y, Hingorani MM, Mukerji I. MutSγ-Induced DNA Conformational Changes Provide Insights into Its Role in Meiotic Recombination. Biophys J 2018; 115:2087-2101. [PMID: 30467025 DOI: 10.1016/j.bpj.2018.10.029] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/16/2018] [Accepted: 10/22/2018] [Indexed: 01/11/2023] Open
Abstract
In many organisms, MutSγ plays a role in meiotic recombination, facilitating crossover formation between homologous chromosomes. Failure to form crossovers leads to improper segregation of chromosomes and aneuploidy, which in humans result in infertility and birth defects. To improve current understanding of MutSγ function, this study investigates the binding affinities and structures of MutSγ in complex with DNA substrates that model homologous recombination intermediates. For these studies, we overexpressed and isolated from Escherichia coli the yeast MutSγ protein Saccharomyces cerevisiae (Sc) Msh4-Msh5. Sc Msh4-Msh5 binds Holliday junction (HJ)-like substrates, 3' overhangs, single-stranded (ss) forks, and the displacement loop with nanomolar affinity. The weakest binding affinities are detected for an intact duplex and open-junction construct. Similar to the human protein, Sc Msh4-Msh5 exhibits the highest affinity for the HJ with a Kd < 0.4 nM in solution. Energy-transfer experiments further demonstrate that DNA structure is modulated by the binding interaction with the largest changes associated with substrates containing an ss end. Upon binding, Sc Msh4-Msh5 displaces the ss away from the duplex in most of the ss-containing intermediates, potentially enabling the binding of RPA and other proteins. In the case of the junction-like intermediates, Msh4-Msh5 binding either stabilizes the existing stacked structure or induces formation of the stacked X conformation. Significantly, we find that upon binding, Msh4-Msh5 stacks an open-junction construct to the same extent as the standard junction. Stabilization of the junction in the stacked conformation is generally refractory to branch migration, which is consistent with a potential role for MutSγ to stabilize HJs and prevent branch migration until resolution by MutLγ. The different binding modalities observed suggest that Msh4-Msh5 not only binds to and stabilizes stacked junctions but also participates in meiotic recombination before junction formation through the stabilization of single-end invasion intermediates.
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Affiliation(s)
- Sudipta Lahiri
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Yan Li
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Manju M Hingorani
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut
| | - Ishita Mukerji
- Department of Molecular Biology and Biochemistry, Molecular Biophysics Program, Wesleyan University, Middletown, Connecticut.
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17
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Female Meiosis: Synapsis, Recombination, and Segregation in Drosophila melanogaster. Genetics 2018; 208:875-908. [PMID: 29487146 PMCID: PMC5844340 DOI: 10.1534/genetics.117.300081] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 10/18/2017] [Indexed: 12/11/2022] Open
Abstract
A century of genetic studies of the meiotic process in Drosophila melanogaster females has been greatly augmented by both modern molecular biology and major advances in cytology. These approaches, and the findings they have allowed, are the subject of this review. Specifically, these efforts have revealed that meiotic pairing in Drosophila females is not an extension of somatic pairing, but rather occurs by a poorly understood process during premeiotic mitoses. This process of meiotic pairing requires the function of several components of the synaptonemal complex (SC). When fully assembled, the SC also plays a critical role in maintaining homolog synapsis and in facilitating the maturation of double-strand breaks (DSBs) into mature crossover (CO) events. Considerable progress has been made in elucidating not only the structure, function, and assembly of the SC, but also the proteins that facilitate the formation and repair of DSBs into both COs and noncrossovers (NCOs). The events that control the decision to mature a DSB as either a CO or an NCO, as well as determining which of the two CO pathways (class I or class II) might be employed, are also being characterized by genetic and genomic approaches. These advances allow a reconsideration of meiotic phenomena such as interference and the centromere effect, which were previously described only by genetic studies. In delineating the mechanisms by which the oocyte controls the number and position of COs, it becomes possible to understand the role of CO position in ensuring the proper orientation of homologs on the first meiotic spindle. Studies of bivalent orientation have occurred in the context of numerous investigations into the assembly, structure, and function of the first meiotic spindle. Additionally, studies have examined the mechanisms ensuring the segregation of chromosomes that have failed to undergo crossing over.
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18
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Testing the effect of paraquat exposure on genomic recombination rates in queens of the western honey bee, Apis mellifera. Genetica 2018; 146:171-178. [PMID: 29397499 DOI: 10.1007/s10709-018-0009-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2017] [Accepted: 01/30/2018] [Indexed: 10/18/2022]
Abstract
The rate of genomic recombination displays evolutionary plasticity and can even vary in response to environmental factors. The western honey bee (Apis mellifera L.) has an extremely high genomic recombination rate but the mechanistic basis for this genome-wide upregulation is not understood. Based on the hypothesis that meiotic recombination and DNA damage repair share common mechanisms in honey bees as in other organisms, we predicted that oxidative stress leads to an increase in recombination rate in honey bees. To test this prediction, we subjected honey bee queens to oxidative stress by paraquat injection and measured the rates of genomic recombination in select genome intervals of offspring produced before and after injection. The evaluation of 26 genome intervals in a total of over 1750 offspring of 11 queens by microsatellite genotyping revealed several significant effects but no overall evidence for a mechanistic link between oxidative stress and increased recombination was found. The results weaken the notion that DNA repair enzymes have a regulatory function in the high rate of meiotic recombination of honey bees, but they do not provide evidence against functional overlap between meiotic recombination and DNA damage repair in honey bees and more mechanistic studies are needed.
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19
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Loss of Drosophila Mei-41/ATR Alters Meiotic Crossover Patterning. Genetics 2017; 208:579-588. [PMID: 29247012 DOI: 10.1534/genetics.117.300634] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 12/14/2017] [Indexed: 11/18/2022] Open
Abstract
Meiotic crossovers must be properly patterned to ensure accurate disjunction of homologous chromosomes during meiosis I. Disruption of the spatial distribution of crossovers can lead to nondisjunction, aneuploidy, gamete dysfunction, miscarriage, or birth defects. One of the earliest identified genes involved in proper crossover patterning is Drosophila mei-41, which encodes the ortholog of the checkpoint kinase ATR. Analysis of hypomorphic mutants suggested the existence of crossover patterning defects, but it was not possible to assess this in null mutants because of maternal-effect embryonic lethality. To overcome this lethality, we constructed mei-41 null mutants in which we expressed wild-type Mei-41 in the germline after completion of meiotic recombination, allowing progeny to survive. We find that crossovers are decreased to about one-third of wild-type levels, but the reduction is not uniform, being less severe in the proximal regions of chromosome 2L than in medial or distal 2L or on the X chromosome. None of the crossovers formed in the absence of Mei-41 require Mei-9, the presumptive meiotic resolvase, suggesting that Mei-41 functions everywhere, despite the differential effects on crossover frequency. Interference appears to be significantly reduced or absent in mei-41 mutants, but the reduction in crossover density in centromere-proximal regions is largely intact. We propose that crossover patterning is achieved in a stepwise manner, with the crossover suppression related to proximity to the centromere occurring prior to and independently of crossover designation and enforcement of interference. In this model, Mei-41 has an essential function in meiotic recombination after the centromere effect is established but before crossover designation and interference occur.
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20
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Natsume T, Nishimura K, Minocherhomji S, Bhowmick R, Hickson ID, Kanemaki MT. Acute inactivation of the replicative helicase in human cells triggers MCM8-9-dependent DNA synthesis. Genes Dev 2017; 31:816-829. [PMID: 28487407 PMCID: PMC5435893 DOI: 10.1101/gad.297663.117] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 04/10/2017] [Indexed: 01/15/2023]
Abstract
DNA replication fork progression can be disrupted at difficult to replicate loci in the human genome, which has the potential to challenge chromosome integrity. This replication fork disruption can lead to the dissociation of the replisome and the formation of DNA damage. To model the events stemming from replisome dissociation during DNA replication perturbation, we used a degron-based system for inducible proteolysis of a subunit of the replicative helicase. We show that MCM2-depleted cells activate a DNA damage response pathway and generate replication-associated DNA double-strand breaks (DSBs). Remarkably, these cells maintain some DNA synthesis in the absence of MCM2, and this requires the MCM8-9 complex, a paralog of the MCM2-7 replicative helicase. We show that MCM8-9 functions in a homologous recombination-based pathway downstream from RAD51, which is promoted by DSB induction. This RAD51/MCM8-9 axis is distinct from the recently described RAD52-dependent DNA synthesis pathway that operates in early mitosis at common fragile sites. We propose that stalled replication forks can be restarted in S phase via homologous recombination using MCM8-9 as an alternative replicative helicase.
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Affiliation(s)
- Toyoaki Natsume
- Division of Molecular Cell Engineering, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
| | - Kohei Nishimura
- Division of Molecular Cell Engineering, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Shizuoka 411-8540, Japan
| | - Sheroy Minocherhomji
- Center for Chromosome Stability.,Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, 2200 Copenhagen N, Denmark
| | - Rahul Bhowmick
- Center for Chromosome Stability.,Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, 2200 Copenhagen N, Denmark
| | - Ian D Hickson
- Center for Chromosome Stability.,Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Panum Institute, 2200 Copenhagen N, Denmark
| | - Masato T Kanemaki
- Division of Molecular Cell Engineering, National Institute of Genetics, Research Organization of Information and Systems (ROIS), Mishima, Shizuoka 411-8540, Japan.,Department of Genetics, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
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21
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Repair of Meiotic DNA Breaks and Homolog Pairing in Mouse Meiosis Requires a Minichromosome Maintenance (MCM) Paralog. Genetics 2016; 205:529-537. [PMID: 27986806 DOI: 10.1534/genetics.116.196808] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 12/06/2016] [Indexed: 11/18/2022] Open
Abstract
The mammalian Mcm-domain containing 2 (Mcmdc2) gene encodes a protein of unknown function that is homologous to the minichromosome maintenance family of DNA replication licensing and helicase factors. Drosophila melanogaster contains two separate genes, the Mei-MCMs, which appear to have arisen from a single ancestral Mcmdc2 gene. The Mei-MCMs are involved in promoting meiotic crossovers by blocking the anticrossover activity of BLM helicase, a function presumably performed by MSH4 and MSH5 in metazoans. Here, we report that MCMDC2-deficient mice of both sexes are viable but sterile. Males fail to produce spermatozoa, and formation of primordial follicles is disrupted in females. Histology and immunocytological analyses of mutant testes revealed that meiosis is arrested in prophase I, and is characterized by persistent meiotic double-stranded DNA breaks (DSBs), failure of homologous chromosome synapsis and XY body formation, and an absence of crossing over. These phenotypes resembled those of MSH4/5-deficient meiocytes. The data indicate that MCMDC2 is essential for invasion of homologous sequences by RAD51- and DMC1-coated single-stranded DNA filaments, or stabilization of recombination intermediates following strand invasion, both of which are needed to drive stable homolog pairing and DSB repair via recombination in mice.
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22
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Hatkevich T, Kohl KP, McMahan S, Hartmann MA, Williams AM, Sekelsky J. Bloom Syndrome Helicase Promotes Meiotic Crossover Patterning and Homolog Disjunction. Curr Biol 2016; 27:96-102. [PMID: 27989672 DOI: 10.1016/j.cub.2016.10.055] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/25/2016] [Accepted: 10/27/2016] [Indexed: 11/28/2022]
Abstract
In most sexually reproducing organisms, crossover formation between homologous chromosomes is necessary for proper chromosome disjunction during meiosis I. During meiotic recombination, a subset of programmed DNA double-strand breaks (DSBs) are repaired as crossovers, with the remainder becoming noncrossovers [1]. Whether a repair intermediate is designated to become a crossover is a highly regulated decision that integrates several crossover patterning processes, both along chromosome arms (interference and the centromere effect) and between chromosomes (crossover assurance) [2]. Because the mechanisms that generate crossover patterning have remained elusive for over a century, it has been difficult to assess the relationship between crossover patterning and meiotic chromosome behavior. We show here that meiotic crossover patterning is lost in Drosophila melanogaster mutants that lack the Bloom syndrome helicase. In the absence of interference and the centromere effect, crossovers are distributed more uniformly along chromosomes. Crossovers even occur on the small chromosome 4, which normally never has meiotic crossovers [3]. Regulated distribution of crossovers between chromosome pairs is also lost, resulting in an elevated frequency of homologs that do not receive a crossover, which in turn leads to elevated nondisjunction.
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Affiliation(s)
- Talia Hatkevich
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA
| | - Kathryn P Kohl
- Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA
| | - Susan McMahan
- Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA
| | - Michaelyn A Hartmann
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA
| | - Andrew M Williams
- Department of Biology, Winthrop University, 701 Oakland Avenue, Rock Hill, SC 29733, USA
| | - Jeff Sekelsky
- Curriculum in Genetics and Molecular Biology, 120 Mason Farm Road, University of North Carolina, Chapel Hill, NC 27599-7264, USA; Department of Biology, University of North Carolina, 120 South Road, Chapel Hill, NC 27599-3280, USA; Integrative Program in Biological and Genome Sciences, 250 Bell Tower Drive, University of North Carolina, Chapel Hill, NC 27599-7100, USA.
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23
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Finsterbusch F, Ravindranathan R, Dereli I, Stanzione M, Tränkner D, Tóth A. Alignment of Homologous Chromosomes and Effective Repair of Programmed DNA Double-Strand Breaks during Mouse Meiosis Require the Minichromosome Maintenance Domain Containing 2 (MCMDC2) Protein. PLoS Genet 2016; 12:e1006393. [PMID: 27760146 PMCID: PMC5070785 DOI: 10.1371/journal.pgen.1006393] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 09/28/2016] [Indexed: 02/06/2023] Open
Abstract
Orderly chromosome segregation during the first meiotic division requires meiotic recombination to form crossovers between homologous chromosomes (homologues). Members of the minichromosome maintenance (MCM) helicase family have been implicated in meiotic recombination. In addition, they have roles in initiation of DNA replication, DNA mismatch repair and mitotic DNA double-strand break repair. Here, we addressed the function of MCMDC2, an atypical yet conserved MCM protein, whose function in vertebrates has not been reported. While we did not find an important role for MCMDC2 in mitotically dividing cells, our work revealed that MCMDC2 is essential for fertility in both sexes due to a crucial function in meiotic recombination. Meiotic recombination begins with the introduction of DNA double-strand breaks into the genome. DNA ends at break sites are resected. The resultant 3-prime single-stranded DNA overhangs recruit RAD51 and DMC1 recombinases that promote the invasion of homologous duplex DNAs by the resected DNA ends. Multiple strand invasions on each chromosome promote the alignment of homologous chromosomes, which is a prerequisite for inter-homologue crossover formation during meiosis. We found that although DNA ends at break sites were evidently resected, and they recruited RAD51 and DMC1 recombinases, these recombinases were ineffective in promoting alignment of homologous chromosomes in the absence of MCMDC2. Consequently, RAD51 and DMC1 foci, which are thought to mark early recombination intermediates, were abnormally persistent in Mcmdc2-/- meiocytes. Importantly, the strand invasion stabilizing MSH4 protein, which marks more advanced recombination intermediates, did not efficiently form foci in Mcmdc2-/- meiocytes. Thus, our work suggests that MCMDC2 plays an important role in either the formation, or the stabilization, of DNA strand invasion events that promote homologue alignment and provide the basis for inter-homologue crossover formation during meiotic recombination.
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Affiliation(s)
| | - Ramya Ravindranathan
- Institute of Physiological Chemistry, Medical Faculty of TU Dresden, Dresden, Germany
| | - Ihsan Dereli
- Institute of Physiological Chemistry, Medical Faculty of TU Dresden, Dresden, Germany
| | - Marcello Stanzione
- Institute of Physiological Chemistry, Medical Faculty of TU Dresden, Dresden, Germany
| | - Daniel Tränkner
- Institute of Physiological Chemistry, Medical Faculty of TU Dresden, Dresden, Germany
| | - Attila Tóth
- Institute of Physiological Chemistry, Medical Faculty of TU Dresden, Dresden, Germany
- * E-mail:
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24
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Minichromosome maintenance complex component 8 mutations cause primary ovarian insufficiency. Fertil Steril 2016; 106:1485-1489.e2. [PMID: 27573988 DOI: 10.1016/j.fertnstert.2016.08.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/05/2016] [Accepted: 08/05/2016] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To investigate whether mutations in the minichromosome maintenance complex component 8 (MCM8) gene were present in 192 patients with sporadic primary ovarian insufficiency (POI). DESIGN Retrospective case-control cohort study. SETTING University-based reproductive medicine center. PATIENT(S) A total of 192 patients with sporadic POI and 312 control women with regular menstruation (192 age-matched women and 120 women >45 years old). INTERVENTION(S) Sanger sequencing was performed in patients with sporadic POI, and potentially pathogenic variants were confirmed in matched controls. DNA damage was induced by mitomycinC (MMC) treatment, and DNA repair capacity was evaluated by histone H2AX phosphorylation level. MAIN OUTCOME MEASURE(S) Sanger sequencing for MCM8 was performed in 192 patients with sporadic POI, and functional experiments were performed to explore the deleterious effects of mutations identified. RESULT(S) Two novel missense variants in MCM8, c. A950T (p. H317L), and c. A1802G (p. H601R), were identified in two patients with POI but absent in 312 controls (the upper 90% confidence limit for the proportion 2/192 is 2.24%). The HeLa cells overexpressing mutant p. H317L and p. H601R showed higher sensitivity to MMC compared with wild type. Furthermore, mutant p. H317L showed decreased repair capacity after MMC treatment with much more histone H2AX phosphorylation remaining after 2 hours of recovery. CONCLUSION(S) Our result suggests novel mutations p. H317L and p. H601R in the MCM8 gene are potentially causative for POI by dysfunctional DNA repair.
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25
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Korunes KL, Noor MAF. Gene conversion and linkage: effects on genome evolution and speciation. Mol Ecol 2016; 26:351-364. [DOI: 10.1111/mec.13736] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 06/07/2016] [Accepted: 06/22/2016] [Indexed: 12/12/2022]
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26
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Whole-Genome Analysis of Individual Meiotic Events in Drosophila melanogaster Reveals That Noncrossover Gene Conversions Are Insensitive to Interference and the Centromere Effect. Genetics 2016; 203:159-71. [PMID: 26944917 PMCID: PMC4858771 DOI: 10.1534/genetics.115.186486] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 02/29/2016] [Indexed: 11/18/2022] Open
Abstract
A century of genetic analysis has revealed that multiple mechanisms control the distribution of meiotic crossover events. In Drosophila melanogaster, two significant positional controls are interference and the strongly polar centromere effect. Here, we assess the factors controlling the distribution of crossovers (COs) and noncrossover gene conversions (NCOs) along all five major chromosome arms in 196 single meiotic divisions to generate a more detailed understanding of these controls on a genome-wide scale. Analyzing the outcomes of single meiotic events allows us to distinguish among different classes of meiotic recombination. In so doing, we identified 291 NCOs spread uniformly among the five major chromosome arms and 541 COs (including 52 double crossovers and one triple crossover). We find that unlike COs, NCOs are insensitive to the centromere effect and do not demonstrate interference. Although the positions of COs appear to be determined predominately by the long-range influences of interference and the centromere effect, each chromosome may display a different pattern of sensitivity to interference, suggesting that interference may not be a uniform global property. In addition, unbiased sequencing of a large number of individuals allows us to describe the formation of de novo copy number variants, the majority of which appear to be mediated by unequal crossing over between transposable elements. This work has multiple implications for our understanding of how meiotic recombination is regulated to ensure proper chromosome segregation and maintain genome stability.
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27
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A sex-inducing pheromone triggers cell cycle arrest and mate attraction in the diatom Seminavis robusta. Sci Rep 2016; 6:19252. [PMID: 26786712 PMCID: PMC4726125 DOI: 10.1038/srep19252] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/04/2015] [Indexed: 01/15/2023] Open
Abstract
Although sexual reproduction is believed to play a major role in the high diversification rates and species richness of diatoms, a mechanistic understanding of diatom life cycle control is virtually lacking. Diatom sexual signalling is controlled by a complex, yet largely unknown, pheromone system. Here, a sex-inducing pheromone (SIP+) of the benthic pennate diatom Seminavis robusta was identified by comparative metabolomics, subsequently purified, and physicochemically characterized. Transcriptome analysis revealed that SIP+ triggers the switch from mitosis-to-meiosis in the opposing mating type, coupled with the transcriptional induction of proline biosynthesis genes, and the release of the proline-derived attraction pheromone. The induction of cell cycle arrest by a pheromone, chemically distinct from the one used to attract the opposite mating type, highlights the existence of a sophisticated mechanism to increase chances of mate finding, while keeping the metabolic losses associated with the release of an attraction pheromone to a minimum.
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28
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Lake CM, Hawley RS. Becoming a crossover-competent DSB. Semin Cell Dev Biol 2016; 54:117-25. [PMID: 26806636 DOI: 10.1016/j.semcdb.2016.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 01/06/2016] [Indexed: 12/16/2022]
Abstract
The proper execution of meiotic recombination (or crossing over) is essential for chromosome segregation during the first meiotic division, and thus this process is regulated by multiple, and often elaborate, mechanisms. Meiotic recombination begins with the programmed induction of DNA double-strand breaks (DSBs), of which only a subset are selected to be repaired into crossovers. This crossover selection process is carried out by a number of pro-crossover proteins that regulate the fashion in which DSBs are repaired. Here, we highlight recent studies regarding the process of DSB fate selection by a family of pro-crossover proteins known as the Zip-3 homologs.
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Affiliation(s)
- Cathleen M Lake
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - R Scott Hawley
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, Kansas University Medical Center, Kansas City, KS 66160, USA.
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29
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Patil S, Moeys S, von Dassow P, Huysman MJJ, Mapleson D, De Veylder L, Sanges R, Vyverman W, Montresor M, Ferrante MI. Identification of the meiotic toolkit in diatoms and exploration of meiosis-specific SPO11 and RAD51 homologs in the sexual species Pseudo-nitzschia multistriata and Seminavis robusta. BMC Genomics 2015; 16:930. [PMID: 26572248 PMCID: PMC4647503 DOI: 10.1186/s12864-015-1983-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 10/04/2015] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Sexual reproduction is an obligate phase in the life cycle of most eukaryotes. Meiosis varies among organisms, which is reflected by the variability of the gene set associated to the process. Diatoms are unicellular organisms that belong to the stramenopile clade and have unique life cycles that can include a sexual phase. RESULTS The exploration of five diatom genomes and one diatom transcriptome led to the identification of 42 genes potentially involved in meiosis. While these include the majority of known meiosis-related genes, several meiosis-specific genes, including DMC1, could not be identified. Furthermore, phylogenetic analyses supported gene identification and revealed ancestral loss and recent expansion in the RAD51 family in diatoms. The two sexual species Pseudo-nitzschia multistriata and Seminavis robusta were used to explore the expression of meiosis-related genes: RAD21, SPO11-2, RAD51-A, RAD51-B and RAD51-C were upregulated during meiosis, whereas other paralogs in these families showed no differential expression patterns, suggesting that they may play a role during vegetative divisions. An almost identical toolkit is shared among Pseudo-nitzschia multiseries and Fragilariopsis cylindrus, as well as two species for which sex has not been observed, Phaeodactylum tricornutum and Thalassiosira pseudonana, suggesting that these two may retain a facultative sexual phase. CONCLUSIONS Our results reveal the conserved meiotic toolkit in six diatom species and indicate that Stramenopiles share major modifications of canonical meiosis processes ancestral to eukaryotes, with important divergences in each Kingdom.
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Affiliation(s)
- Shrikant Patil
- Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Naples, Italy.
| | - Sara Moeys
- Department of Biology, Protistology and Aquatic Ecology, Ghent University, 9000, Ghent, Belgium. .,Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. .,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
| | - Peter von Dassow
- Facultad de Ciencias Biológicas, Instituto Milenio de Oceanografía, Pontificia Universidad Católica de Chile, Santiago, Chile. .,UMI 3614, Evolutionary Biology and Ecology of Algae, CNRS-UPMC Sorbonne Universités, PUCCh, UACH, Station Biologique de Roscoff, Roscoff, France.
| | - Marie J J Huysman
- Department of Biology, Protistology and Aquatic Ecology, Ghent University, 9000, Ghent, Belgium. .,Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. .,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
| | - Daniel Mapleson
- The Genome Analysis Centre (TGAC), Norwich Research Park, Norwich, NR4 7UH, UK.
| | - Lieven De Veylder
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), 9052, Ghent, Belgium. .,Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052, Ghent, Belgium.
| | - Remo Sanges
- Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Naples, Italy.
| | - Wim Vyverman
- Department of Biology, Protistology and Aquatic Ecology, Ghent University, 9000, Ghent, Belgium.
| | - Marina Montresor
- Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Naples, Italy.
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30
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Cai L, Zhao K, Yuan X. Expression of minichromosome maintenance 8 in chronic myelogenous leukemia. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2015; 8:14180-14188. [PMID: 26823731 PMCID: PMC4713517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 10/28/2015] [Indexed: 06/05/2023]
Abstract
OBJECTIVES Minichromosome maintenance 8 (MCM8) is identified as an initiating helicase involved in DNA elongation and involved in cancer. However, little information is available for the role of MCM8 on chronic myelogenous leukemia (CML). We aimed to explore the expression and effect of MCM8 on CML. METHODS Peripheral blood mononuclear cells (PBMC) and bone marrow mononuclear cells (BMMC) were prepared from six patients with CML and three healthy individuals. The mRNA levels of MCM8 were determined and compared. The expression of MCM8 was silenced by small interfering RNA (siRNA) approach in human CML cell line K562. After transfection with MCM8 siRNA, cell viability and apoptotic rate were analyzed, as well as the protein expression levels of Caspase-3 and B-cell lymphoma (Bcl)-xL. RESULTS Relative mRNA levels of MCM8 were both significantly higher in PBMC and BMMC from CML patients than those in healthy individuals (P < 0.05). The cell viability was significantly reduced while the apoptotic rate was statistically increased by knockdown of MCM8 compared to control group or the scramble siRNA group (both P < 0.05). Moreover, the protein expression levels of Caspase-3 were significantly increased (P < 0.05), and while the levels of Bcl-xL were statistically reduced (P < 0.05) compared to the control group or the scramble siRNA group. CONCLUSION MCM8 plays a significant role in CML, and knockdown of MCM8 might be a potentially targeted therapy for CML.
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MESH Headings
- Apoptosis
- Case-Control Studies
- Caspase 3/metabolism
- Cell Survival
- Gene Expression Regulation, Leukemic
- Humans
- K562 Cells
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/metabolism
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Minichromosome Maintenance Proteins/genetics
- Minichromosome Maintenance Proteins/metabolism
- RNA Interference
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Time Factors
- Transfection
- bcl-X Protein/metabolism
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Affiliation(s)
- Lili Cai
- Department of Blood Transfusion, The First People’s Hospital of Shangqiu CityShangqiu 476000, Henan Province, P. R. China
| | - Kai Zhao
- Department of Clinical Laboratory, The First People’s Hospital of Shangqiu CityShangqiu 476000, Henan Province, P. R. China
| | - Xuejie Yuan
- Shangqiu Medical CollegeShangqiu 476000, Henan Province, P. R. China
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Abstract
The study of homologous recombination has its historical roots in meiosis. In this context, recombination occurs as a programmed event that culminates in the formation of crossovers, which are essential for accurate chromosome segregation and create new combinations of parental alleles. Thus, meiotic recombination underlies both the independent assortment of parental chromosomes and genetic linkage. This review highlights the features of meiotic recombination that distinguish it from recombinational repair in somatic cells, and how the molecular processes of meiotic recombination are embedded and interdependent with the chromosome structures that characterize meiotic prophase. A more in-depth review presents our understanding of how crossover and noncrossover pathways of meiotic recombination are differentiated and regulated. The final section of this review summarizes the studies that have defined defective recombination as a leading cause of pregnancy loss and congenital disease in humans.
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Affiliation(s)
- Neil Hunter
- Howard Hughes Medical Institute, Department of Microbiology & Molecular Genetics, Department of Molecular & Cellular Biology, Department of Cell Biology & Human Anatomy, University of California Davis, Davis, California 95616
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32
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Lee KY, Im JS, Shibata E, Park J, Handa N, Kowalczykowski SC, Dutta A. MCM8-9 complex promotes resection of double-strand break ends by MRE11-RAD50-NBS1 complex. Nat Commun 2015; 6:7744. [PMID: 26215093 PMCID: PMC4525285 DOI: 10.1038/ncomms8744] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 06/08/2015] [Indexed: 11/20/2022] Open
Abstract
MCM8-9 complex is required for homologous recombination (HR)-mediated repair of double-strand breaks (DSBs). Here we report that MCM8-9 is required for DNA resection by MRN (MRE11-RAD50-NBS1) at DSBs to generate ssDNA. MCM8-9 interacts with MRN and is required for the nuclease activity and stable association of MRN with DSBs. The ATPase motifs of MCM8-9 are required for recruitment of MRE11 to foci of DNA damage. Homozygous deletion of the MCM9 found in various cancers sensitizes a cancer cell line to interstrand-crosslinking (ICL) agents. A cancer-derived point mutation or an SNP on MCM8 associated with premature ovarian failure (POF) diminishes the functional activity of MCM8. Therefore, the MCM8-9 complex facilitates DNA resection by the MRN complex during HR repair, genetic or epigenetic inactivation of MCM8 or MCM9 are seen in human cancers, and genetic inactivation of MCM8 may be the basis of a POF syndrome.
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Affiliation(s)
- Kyung Yong Lee
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Jordan Hall, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908 USA
| | - Jun-Sub Im
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Jordan Hall, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908 USA
| | - Etsuko Shibata
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Jordan Hall, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908 USA
| | - Jonghoon Park
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Jordan Hall, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908 USA
| | - Naofumi Handa
- Department of Microbiology and Molecular Genetics, University of California, Briggs Hall, One Shields Avenue, Davis, California 95616-8665 USA
| | - Stephen C. Kowalczykowski
- Department of Microbiology and Molecular Genetics, University of California, Briggs Hall, One Shields Avenue, Davis, California 95616-8665 USA
| | - Anindya Dutta
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Jordan Hall, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908 USA
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33
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Tenenbaum-Rakover Y, Weinberg-Shukron A, Renbaum P, Lobel O, Eideh H, Gulsuner S, Dahary D, Abu-Rayyan A, Kanaan M, Levy-Lahad E, Bercovich D, Zangen D. Minichromosome maintenance complex component 8 (MCM8) gene mutations result in primary gonadal failure. J Med Genet 2015; 52:391-9. [DOI: 10.1136/jmedgenet-2014-102921] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 03/25/2015] [Indexed: 11/03/2022]
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Kusch T. Brca2-Pds5 complexes mobilize persistent meiotic recombination sites to the nuclear envelope. J Cell Sci 2015; 128:717-27. [PMID: 25588834 DOI: 10.1242/jcs.159988] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Homologous recombination is required for reciprocal exchange between homologous chromosome arms during meiosis. Only select meiotic recombination events become chromosomal crossovers; the majority of recombination outcomes are noncrossovers. Growing evidence suggests that crossovers are repaired after noncrossovers. Here, I report that persisting recombination sites are mobilized to the nuclear envelope of Drosophila pro-oocytes during mid-pachytene. Their number correlates with the average crossover rate per meiosis. Proteomic and interaction studies reveal that the recombination mediator Brca2 associates with lamin and the cohesion factor Pds5 to secure persistent recombination sites at the nuclear envelope. In Rad51(-/-) females, all persistent DNA breaks are directed to the nuclear envelope. By contrast, a reduction of Pds5 or Brca2 levels abolishes the movement and has a negative impact on crossover rates. The data suggest that persistent meiotic DNA double-strand breaks might correspond to crossovers, which are mobilized to the nuclear envelope for their repair. The identification of Brca2-Pds5 complexes as key mediators of this process provides a first mechanistic explanation for the contribution of lamins and cohesins to meiotic recombination.
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Affiliation(s)
- Thomas Kusch
- Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, NJ 08854, USA
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35
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Eliminating both canonical and short-patch mismatch repair in Drosophila melanogaster suggests a new meiotic recombination model. PLoS Genet 2014; 10:e1004583. [PMID: 25188408 PMCID: PMC4154643 DOI: 10.1371/journal.pgen.1004583] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 07/08/2014] [Indexed: 01/31/2023] Open
Abstract
In most meiotic systems, recombination is essential to form connections between homologs that ensure their accurate segregation from one another. Meiotic recombination is initiated by DNA double-strand breaks that are repaired using the homologous chromosome as a template. Studies of recombination in budding yeast have led to a model in which most early repair intermediates are disassembled to produce noncrossovers. Selected repair events are stabilized so they can proceed to form double-Holliday junction (dHJ) intermediates, which are subsequently resolved into crossovers. This model is supported in yeast by physical isolation of recombination intermediates, but the extent to which it pertains to animals is unknown. We sought to test this model in Drosophila melanogaster by analyzing patterns of heteroduplex DNA (hDNA) in recombination products. Previous attempts to do this have relied on knocking out the canonical mismatch repair (MMR) pathway, but in both yeast and Drosophila the resulting recombination products are complex and difficult to interpret. We show that, in Drosophila, this complexity results from a secondary, short-patch MMR pathway that requires nucleotide excision repair. Knocking out both canonical and short-patch MMR reveals hDNA patterns that reveal that many noncrossovers arise after both ends of the break have engaged with the homolog. Patterns of hDNA in crossovers could be explained by biased resolution of a dHJ; however, considering the noncrossover and crossover results together suggests a model in which a two-end engagement intermediate with unligated HJs can be disassembled by a helicase to a produce noncrossover or nicked by a nuclease to produce a crossover. While some aspects of this model are similar to the model from budding yeast, production of both noncrossovers and crossovers from a single, late intermediate is a fundamental difference that has important implications for crossover control. During meiosis, breaks are introduced into the DNA, then repaired to give either crossovers between homologous chromosomes (these help to ensure correct segregation of these chromosomes from one another), or non-crossover products. Meiotic break repair mechanisms have been best studied in budding yeast, leading to detailed molecular models. Technical limitations have prevented directly testing these models in multi-cellular organisms. One approach that has been tried is to map segments of DNA that are mismatched, since different models predict different arrangements. Mismatches are usually repaired quickly, so analyzing these patterns requires eliminating mismatch repair processes. Although others have knocked out the primary mismatch repair system, we have now, for the first time in an animal, identified the secondary repair pathway and eliminated it and the primary pathway simultaneously. We then analyzed mismatches produced during meiosis. Though the results can be fit to the most popular current model from yeast, if some modifications are made, we also consider a simpler model that incorporates elements of the current model and of earlier models.
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Lee R, Lai H, Malik SB, Saldarriaga JF, Keeling PJ, Slamovits CH. Analysis of EST data of the marine protist Oxyrrhis marina, an emerging model for alveolate biology and evolution. BMC Genomics 2014; 15:122. [PMID: 24512041 PMCID: PMC3942190 DOI: 10.1186/1471-2164-15-122] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2013] [Accepted: 02/06/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND The alveolates include a large number of important lineages of protists and algae, among which are three major eukaryotic groups: ciliates, apicomplexans and dinoflagellates. Collectively alveolates are present in virtually every environment and include a vast diversity of cell shapes, molecular and cellular features and feeding modes including lifestyles such as phototrophy, phagotrophy/predation and intracellular parasitism, in addition to a variety of symbiotic associations. Oxyrrhis marina is a well-known model for heterotrophic protist biology, and is now emerging as a useful organism to explore the many changes that occurred during the origin and diversification of dinoflagellates by virtue of its phylogenetic position at the base of the dinoflagellate tree. RESULTS We have generated and analysed expressed sequence tag (EST) sequences from the alveolate Oxyrrhis marina in order to shed light on the evolution of a number of dinoflagellate characteristics, especially regarding the emergence of highly unusual genomic features. We found that O. marina harbours extensive gene redundancy, indicating high rates of gene duplication and transcription from multiple genomic loci. In addition, we observed a correlation between expression level and copy number in several genes, suggesting that copy number may contribute to determining transcript levels for some genes. Finally, we analyze the genes and predicted products of the recently discovered Dinoflagellate Viral Nuclear Protein, and several cases of horizontally acquired genes. CONCLUSION The dataset presented here has proven very valuable for studying this important group of protists. Our analysis indicates that gene redundancy is a pervasive feature of dinoflagellate genomes, thus the mechanisms involved in its generation must have arisen early in the evolution of the group.
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Affiliation(s)
- Renny Lee
- Department of Biochemistry and Molecular Biology, Dalhousie University, B3H4R2 Halifax, NS, Canada
| | - Hugo Lai
- Department of Biochemistry and Molecular Biology, Dalhousie University, B3H4R2 Halifax, NS, Canada
| | - Shehre Banoo Malik
- Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, B3H4R2 Halifax, NS, Canada
| | - Juan F Saldarriaga
- Botany Department, University of British Columbia, V6T1Z4 Vancouver, BS, Canada
| | - Patrick J Keeling
- Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Alberta, Canada
- Botany Department, University of British Columbia, V6T1Z4 Vancouver, BS, Canada
| | - Claudio H Slamovits
- Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, Alberta, Canada
- Department of Biochemistry and Molecular Biology, Dalhousie University, B3H4R2 Halifax, NS, Canada
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Variation in meiotic recombination frequencies between allelic transgenes inserted at different sites in the Drosophila melanogaster genome. G3-GENES GENOMES GENETICS 2013; 3:1419-27. [PMID: 23797104 PMCID: PMC3737181 DOI: 10.1534/g3.113.006411] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Meiotic crossovers are distributed nonrandomly across the genome. Classic studies in Drosophila suggest that the position of a gene along a chromosome arm can affect the outcome of the recombination process, with proximity to the centromere being associated with lower crossing over. To examine this phenomenon molecularly, we developed an assay that measures meiotic crossovers and noncrossover gene conversions between allelic transgenes inserted into different genomic positions. To facilitate collecting a large number of virgin females, we developed a useful genetic system that kills males and undesired classes of females. We found that the recombination frequency at a site in the middle of the X chromosome, where crossovers are normally frequent, was similar to the frequency at the centromere-proximal end of the euchromatin, where crossovers are normally infrequent. In contrast, we recovered no recombinants--crossovers or noncrossovers--at a site on chromosome 4 and at a site toward the distal end of the X chromosome. These results suggest that local sequence or chromatin features have a stronger impact on recombination rates in this transgene assay than position along the chromosome arm.
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Bell SP, Kaguni JM. Helicase loading at chromosomal origins of replication. Cold Spring Harb Perspect Biol 2013; 5:cshperspect.a010124. [PMID: 23613349 DOI: 10.1101/cshperspect.a010124] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Loading of the replicative DNA helicase at origins of replication is of central importance in DNA replication. As the first of the replication fork proteins assemble at chromosomal origins of replication, the loaded helicase is required for the recruitment of the rest of the replication machinery. In this work, we review the current knowledge of helicase loading at Escherichia coli and eukaryotic origins of replication. In each case, this process requires both an origin recognition protein as well as one or more additional proteins. Comparison of these events shows intriguing similarities that suggest a similar underlying mechanism, as well as critical differences that likely reflect the distinct processes that regulate helicase loading in bacterial and eukaryotic cells.
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Affiliation(s)
- Stephen P Bell
- Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Gambus A, Blow JJ. Mcm8 and Mcm9 form a dimeric complex in Xenopus laevis egg extract that is not essential for DNA replication initiation. Cell Cycle 2013; 12:1225-32. [PMID: 23518502 PMCID: PMC3674087 DOI: 10.4161/cc.24310] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 03/12/2013] [Accepted: 03/14/2013] [Indexed: 11/22/2022] Open
Abstract
Hexameric complexes of the six related Mcm2-7 proteins form the core of the replicative helicase. Two other proteins, Mcm8 and Mcm9, with significant homology to Mcm2-7 were first shown to play distinct roles during DNA replication in Xenopus laevis egg extract. Recent work has revealed that Mcm8 and 9 form a complex that plays a role during homologous recombination in human, chicken and mouse cells. We have therefore re-examined the behavior of the Xenopus homologs of these proteins. We show that Mcm8 and Mcm9 form a dimeric complex in Xenopus egg extract. They both associate with chromatin at later stages of DNA replication, and this association is stimulated by DNA damage, suggesting that their function is analogous to the one described in higher eukaryotes. In contrast to previous reports, we do not find Mcm9 essential for loading of Mcm2-7 complex onto chromatin during origin licensing nor detect its interaction with Cdt1 origin licensing factor. Altogether, we conclude that the role Mcm8 and Mcm9 play in Xenopus egg extract is not different from recent findings in higher eukaryotes, consistent with an evolutionary conservation of their function.
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Affiliation(s)
- Agnieszka Gambus
- School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
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40
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The MCM8-MCM9 complex promotes RAD51 recruitment at DNA damage sites to facilitate homologous recombination. Mol Cell Biol 2013; 33:1632-44. [PMID: 23401855 DOI: 10.1128/mcb.01503-12] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The minichromosome maintenance protein homologs MCM8 and MCM9 have previously been implicated in DNA replication elongation and prereplication complex (pre-RC) formation, respectively. We found that MCM8 and MCM9 physically associate with each other and that MCM8 is required for the stability of MCM9 protein in mammalian cells. Depletion of MCM8 or MCM9 in human cancer cells or the loss of function MCM9 mutation in mouse embryo fibroblasts sensitizes cells to the DNA interstrand cross-linking (ICL) agent cisplatin. Consistent with a role in the repair of ICLs by homologous recombination (HR), knockdown of MCM8 or MCM9 significantly reduces HR repair efficiency. Chromatin immunoprecipitation analysis using human DR-GFP cells or Xenopus egg extract demonstrated that MCM8 and MCM9 proteins are rapidly recruited to DNA damage sites and promote RAD51 recruitment. Thus, these two metazoan-specific MCM homologs are new components of HR and may represent novel targets for treating cancer in combination with DNA cross-linking agents.
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41
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Abstract
The MCM proteins are best known for their role in DNA replication, MCM2-7 forming the replicative helicase. Now, two reports in this issue of Molecular Cell, Nishimura et al. (2012) and Lutzmann et al. (2012) show the less well understood MCM8 and MCM9 to be crucial for effective homologous recombination.
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Crismani W, Portemer V, Froger N, Chelysheva L, Horlow C, Vrielynck N, Mercier R. MCM8 is required for a pathway of meiotic double-strand break repair independent of DMC1 in Arabidopsis thaliana. PLoS Genet 2013; 9:e1003165. [PMID: 23300481 PMCID: PMC3536722 DOI: 10.1371/journal.pgen.1003165] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 10/28/2012] [Indexed: 11/25/2022] Open
Abstract
Mini-chromosome maintenance (MCM) 2–9 proteins are related helicases. The first six, MCM2–7, are essential for DNA replication in all eukaryotes. In contrast, MCM8 is not always conserved in eukaryotes but is present in Arabidopsis thaliana. MCM8 is required for 95% of meiotic crossovers (COs) in Drosophila and is essential for meiosis completion in mouse, prompting us to study this gene in Arabidopsis meiosis. Three allelic Atmcm8 mutants showed a limited level of chromosome fragmentation at meiosis. This defect was dependent on programmed meiotic double-strand break (DSB) formation, revealing a role for AtMCM8 in meiotic DSB repair. In contrast, CO formation was not affected, as shown both genetically and cytologically. The Atmcm8 DSB repair defect was greatly amplified in the absence of the DMC1 recombinase or in mutants affected in DMC1 dynamics (sds, asy1). The Atmcm8 fragmentation defect was also amplified in plants heterozygous for a mutation in either recombinase, DMC1 or RAD51. Finally, in the context of absence of homologous chromosomes (i.e. haploid), mutation of AtMCM8 also provoked a low level of chromosome fragmentation. This fragmentation was amplified by the absence of DMC1 showing that both MCM8 and DMC1 can promote repair on the sister chromatid in Arabidopsis haploids. Altogether, this establishes a role for AtMCM8 in meiotic DSB repair, in parallel to DMC1. We propose that MCM8 is involved with RAD51 in a backup pathway that repairs meiotic DSB without giving CO when the major pathway, which relies on DMC1, fails. Species that reproduce sexually have two copies of each chromosome, inherited from their father and mother. During a special cell division called meiosis, these two chromosomes are mixed by homologous recombination to give genetically unique chromosomes that will be transmitted to the next generation. This recombination process is initiated by DNA breaks that must be repaired efficiently to maintain fertility. Using the model plant Arabidopsis thaliana we revealed here that the gene AtMCM8 is required to repair a subset of these DNA breaks. However MCM8 appears to not be required for recombination with the homologous chromosome. Instead MCM8 appears to be involved in a safety system that operates to repair DNA breaks that have not been used for homologous recombination. Interestingly the equivalent gene also has an essential meiotic function in the fly and the mouse. However the three species require MCM8 for different aspects of meiosis.
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Affiliation(s)
- Wayne Crismani
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, Versailles, France
| | - Virginie Portemer
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, Versailles, France
| | - Nicole Froger
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, Versailles, France
| | - Liudmila Chelysheva
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, Versailles, France
| | - Christine Horlow
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, Versailles, France
| | - Nathalie Vrielynck
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, Versailles, France
| | - Raphaël Mercier
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, Versailles, France
- * E-mail:
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Chen SH, Plank JL, Willcox S, Griffith JD, Hsieh TS. Improved methods for creating migratable Holliday junction substrates. Nucleic Acids Res 2012; 41:e60. [PMID: 23275569 PMCID: PMC3597647 DOI: 10.1093/nar/gks1343] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Previously, we published a method for creating a novel DNA substrate, the double Holliday junction substrate. This substrate contains two Holliday junctions that are mobile, topologically constrained and separated by a distance comparable with conversion tract lengths. Although useful for studying late stage homologous recombination in vitro, construction of the substrate requires significant effort. In particular, there are three bottlenecks: (i) production of large quantities of single-stranded DNA; (ii) the loss of a significant portion of the DNA following the recombination step; and (iii) the loss of DNA owing to inefficient gel extraction. To address these limitations, we have made the following changes to the protocol: (i) use of a helper plasmid, rather than exogenous helper phage, to produce single-stranded DNA; (ii) use of the unidirectional ϕC31 integrase system in place of the bidirectional Cre recombinase reaction; and (iii) gel extraction by DNA diffusion. Here, we describe the changes made to the materials and methods and characterize the substrates that can be produced, including migratable single Holliday junctions, hemicatenanes and a quadruple Holliday junction substrate.
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Kohl KP, Jones CD, Sekelsky J. Evolution of an MCM complex in flies that promotes meiotic crossovers by blocking BLM helicase. Science 2012; 338:1363-5. [PMID: 23224558 DOI: 10.1126/science.1228190] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Generation of meiotic crossovers in many eukaryotes requires the elimination of anti-crossover activities by using the Msh4-Msh5 heterodimer to block helicases. Msh4 and Msh5 have been lost from the flies Drosophila and Glossina, but we identified a complex of minichromosome maintenance (MCM) proteins that functionally replace Msh4-Msh5. We found that REC, an ortholog of MCM8 that evolved under strong positive selection in flies, interacts with MEI-217 and MEI-218, which arose from a previously undescribed metazoan-specific MCM protein. Meiotic crossovers were reduced in Drosophila rec, mei-217, and mei-218 mutants; however, removal of the Bloom syndrome helicase (BLM) ortholog restored crossovers. Thus, MCMs were co-opted into a novel complex that replaced the meiotic pro-crossover function of Msh4-Msh5 in flies.
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Affiliation(s)
- Kathryn P Kohl
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
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45
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Lutzmann M, Grey C, Traver S, Ganier O, Maya-Mendoza A, Ranisavljevic N, Bernex F, Nishiyama A, Montel N, Gavois E, Forichon L, de Massy B, Méchali M. MCM8- and MCM9-deficient mice reveal gametogenesis defects and genome instability due to impaired homologous recombination. Mol Cell 2012; 47:523-34. [PMID: 22771120 DOI: 10.1016/j.molcel.2012.05.048] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 03/21/2012] [Accepted: 05/31/2012] [Indexed: 10/28/2022]
Abstract
We generated knockout mice for MCM8 and MCM9 and show that deficiency for these genes impairs homologous recombination (HR)-mediated DNA repair during gametogenesis and somatic cells cycles. MCM8(-/-) mice are sterile because spermatocytes are blocked in meiotic prophase I, and females have only arrested primary follicles and frequently develop ovarian tumors. MCM9(-/-) females also are sterile as ovaries are completely devoid of oocytes. In contrast, MCM9(-/-) testes produce spermatozoa, albeit in much reduced quantity. Mcm8(-/-) and Mcm9(-/-) embryonic fibroblasts show growth defects and chromosomal damage and cannot overcome a transient inhibition of replication fork progression. In these cells, chromatin recruitment of HR factors like Rad51 and RPA is impaired and HR strongly reduced. We further demonstrate that MCM8 and MCM9 form a complex and that they coregulate their stability. Our work uncovers essential functions of MCM8 and MCM9 in HR-mediated DSB repair during gametogenesis, replication fork maintenance, and DNA repair.
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Affiliation(s)
- Malik Lutzmann
- DNA Replication and Genome Dynamics, Institute of Human Genetics, CNRS, 141 Rue de la Cardonille, 34396 Montpellier, Cedex 5, France
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Nishimura K, Ishiai M, Horikawa K, Fukagawa T, Takata M, Takisawa H, Kanemaki MT. Mcm8 and Mcm9 form a complex that functions in homologous recombination repair induced by DNA interstrand crosslinks. Mol Cell 2012; 47:511-22. [PMID: 22771115 DOI: 10.1016/j.molcel.2012.05.047] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2012] [Revised: 05/14/2012] [Accepted: 05/31/2012] [Indexed: 01/09/2023]
Abstract
DNA interstrand crosslinks (ICLs) are highly toxic lesions that stall the replication fork to initiate the repair process during the S phase of vertebrates. Proteins involved in Fanconi anemia (FA), nucleotide excision repair (NER), and translesion synthesis (TS) collaboratively lead to homologous recombination (HR) repair. However, it is not understood how ICL-induced HR repair is carried out and completed. Here, we showed that the replicative helicase-related Mcm family of proteins, Mcm8 and Mcm9, forms a complex required for HR repair induced by ICLs. Chicken DT40 cells lacking MCM8 or MCM9 are viable but highly sensitive to ICL-inducing agents, and exhibit more chromosome aberrations in the presence of mitomycin C compared with wild-type cells. During ICL repair, Mcm8 and Mcm9 form nuclear foci that partly colocalize with Rad51. Mcm8-9 works downstream of the FA and BRCA2/Rad51 pathways, and is required for HR that promotes sister chromatid exchanges, probably as a hexameric ATPase/helicase.
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Affiliation(s)
- Kohei Nishimura
- Center for Frontier Research, National Institute of Genetics, Research Organization of Information and Systems, Yata 1111, Mishima, Shizuoka 411-8540, Japan
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Genetic markers of ovarian follicle number and menopause in women of multiple ethnicities. Hum Genet 2012; 131:1709-24. [PMID: 22696150 PMCID: PMC3470691 DOI: 10.1007/s00439-012-1184-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 05/23/2012] [Indexed: 01/22/2023]
Abstract
Oocyte loss has a significant impact on fertility and somatic health. Yet, we know little about factors that impact this process. We sought to identify genetic variants associated with ovarian reserve (oocyte number as measured by antral follicle count, AFC). Based on recently published genome-wide scans that identified loci associated with age of menopause, we also sought to test our hypothesis that follicle number and menopausal age share underlying genetic associations. We analyzed menopause-related variants for association with follicle number in an independent population of approximately 450 reproductive-aged women of European and African ancestry; these women were assessed for AFC, anthropometric, clinical, and lifestyle factors. One SNP strongly associated with later menopausal age in Caucasian women (+1.07 ± 0.11 years) in previous work was also associated with higher follicle counts in Caucasians (+2.79 ± 1.67 follicles) in our study. This variant is within the Minichromosome Maintenance Complex Component 8 (MCM8) gene, which we found was expressed within oocytes in follicles of the human ovary. In genome-wide scans of AFC, we also identified one marginally genome-wide and several nominally significant SNPs within several other genes associated with follicle number in both ethnic groups. Further, there were overlapping variants associated with multiple ovarian reserve markers (AFC, serum hormone levels, menopausal age). This study provides the first evidence for direct genetic associations underlying both follicle number and menopause and identifies novel candidate genes. Genetic variants associated with ovarian reserve may facilitate discovery of genetic markers to predict reproductive health and lifespan in women.
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Lake CM, Hawley RS. The molecular control of meiotic chromosomal behavior: events in early meiotic prophase in Drosophila oocytes. Annu Rev Physiol 2012; 74:425-51. [PMID: 22335798 DOI: 10.1146/annurev-physiol-020911-153342] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We review the critical events in early meiotic prophase in Drosophila melanogaster oocytes. We focus on four aspects of this process: the formation of the synaptonemal complex (SC) and its role in maintaining homologous chromosome pairings, the critical roles of the meiosis-specific process of centromere clustering in the formation of a full-length SC, the mechanisms by which preprogrammed double-strand breaks initiate meiotic recombination, and the checkpoints that govern the progression and coordination of these processes. Central to this discussion are the roles that somatic pairing events play in establishing the necessary conditions for proper SC formation, the roles of centromere pairing in synapsis initiation, and the mechanisms by which oocytes detect failures in SC formation and/or recombination. Finally, we correlate what is known in Drosophila oocytes with our understanding of these processes in other systems.
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Affiliation(s)
- Cathleen M Lake
- Stowers Institute for Medical Research, Kansas City, Missouri 64110, USA.
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Abstract
Repair of meiotic double-strand breaks (DSBs) uses the homolog and recombination to yield crossovers while alternative pathways such as nonhomologous end joining (NHEJ) are suppressed. Our results indicate that NHEJ is blocked at two steps of DSB repair during meiotic prophase: first by the activity of the MCM-like protein MEI-218, which is required for crossover formation, and, second, by Rad51-related proteins SPN-B (XRCC3) and SPN-D (RAD51C), which physically interact and promote homologous recombination (HR). We further show that the MCM-like proteins also promote the activity of the DSB repair checkpoint pathway, indicating an early requirement for these proteins in DSB processing. We propose that when a meiotic DSB is formed in the absence of both MEI-218 and SPN-B or SPN-D, a DSB substrate is generated that can enter the NHEJ repair pathway. Indeed, due to its high error rate, multiple barriers may have evolved to prevent NHEJ activity during meiosis.
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50
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A Whole-Chromosome Analysis of Meiotic Recombination in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2012; 2:249-60. [PMID: 22384403 PMCID: PMC3284332 DOI: 10.1534/g3.111.001396] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/01/2011] [Indexed: 11/18/2022]
Abstract
Although traditional genetic assays have characterized the pattern of crossing over across the genome in Drosophila melanogaster, these assays could not precisely define the location of crossovers. Even less is known about the frequency and distribution of noncrossover gene conversion events. To assess the specific number and positions of both meiotic gene conversion and crossover events, we sequenced the genomes of male progeny from females heterozygous for 93,538 X chromosomal single-nucleotide and InDel polymorphisms. From the analysis of the 30 F1 hemizygous X chromosomes, we detected 15 crossover and 5 noncrossover gene conversion events. Taking into account the nonuniform distribution of polymorphism along the chromosome arm, we estimate that most oocytes experience 1 crossover event and 1.6 gene conversion events per X chromosome pair per meiosis. An extrapolation to the entire genome would predict approximately 5 crossover events and 8.6 conversion events per meiosis. Mean gene conversion tract lengths were estimated to be 476 base pairs, yielding a per nucleotide conversion rate of 0.86 × 10(-5) per meiosis. Both of these values are consistent with estimates of conversion frequency and tract length obtained from studies of rosy, the only gene for which gene conversion has been studied extensively in Drosophila. Motif-enrichment analysis revealed a GTGGAAA motif that was enriched near crossovers but not near gene conversions. The low-complexity and frequent occurrence of this motif may in part explain why, in contrast to mammalian systems, no meiotic crossover hotspots have been found in Drosophila.
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