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Toraason E, Salagean A, Almanzar DE, Brown JE, Richter CM, Kurhanewicz NA, Rog O, Libuda DE. BRCA1/BRC-1 and SMC-5/6 regulate DNA repair pathway engagement during Caenorhabditis elegans meiosis. eLife 2024; 13:e80687. [PMID: 39115289 PMCID: PMC11368404 DOI: 10.7554/elife.80687] [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: 05/31/2022] [Accepted: 08/07/2024] [Indexed: 09/03/2024] Open
Abstract
The preservation of genome integrity during sperm and egg development is vital for reproductive success. During meiosis, the tumor suppressor BRCA1/BRC-1 and structural maintenance of chromosomes 5/6 (SMC-5/6) complex genetically interact to promote high fidelity DNA double strand break (DSB) repair, but the specific DSB repair outcomes these proteins regulate remain unknown. Using genetic and cytological methods to monitor resolution of DSBs with different repair partners in Caenorhabditis elegans, we demonstrate that both BRC-1 and SMC-5 repress intersister crossover recombination events. Sequencing analysis of conversion tracts from homolog-independent DSB repair events further indicates that BRC-1 regulates intersister/intrachromatid noncrossover conversion tract length. Moreover, we find that BRC-1 specifically inhibits error prone repair of DSBs induced at mid-pachytene. Finally, we reveal functional interactions of BRC-1 and SMC-5/6 in regulating repair pathway engagement: BRC-1 is required for localization of recombinase proteins to DSBs in smc-5 mutants and enhances DSB repair defects in smc-5 mutants by repressing theta-mediated end joining (TMEJ). These results are consistent with a model in which some functions of BRC-1 act upstream of SMC-5/6 to promote recombination and inhibit error-prone DSB repair, while SMC-5/6 acts downstream of BRC-1 to regulate the formation or resolution of recombination intermediates. Taken together, our study illuminates the coordinated interplay of BRC-1 and SMC-5/6 to regulate DSB repair outcomes in the germline.
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Affiliation(s)
- Erik Toraason
- Institute of Molecular Biology, Department of Biology, University of OregonEugeneUnited States
| | - Alina Salagean
- Institute of Molecular Biology, Department of Biology, University of OregonEugeneUnited States
| | - David E Almanzar
- School of Biological Sciences and Center for Cell and Genome Sciences, University of UtahSalt Lake CityUnited States
| | - Jordan E Brown
- Institute of Molecular Biology, Department of Biology, University of OregonEugeneUnited States
| | - Colette M Richter
- Institute of Molecular Biology, Department of Biology, University of OregonEugeneUnited States
| | - Nicole A Kurhanewicz
- Institute of Molecular Biology, Department of Biology, University of OregonEugeneUnited States
| | - Ofer Rog
- School of Biological Sciences and Center for Cell and Genome Sciences, University of UtahSalt Lake CityUnited States
| | - Diana E Libuda
- Institute of Molecular Biology, Department of Biology, University of OregonEugeneUnited States
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2
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Hernández Sánchez-Rebato M, Schubert V, White CI. Meiotic double-strand break repair DNA synthesis tracts in Arabidopsis thaliana. PLoS Genet 2024; 20:e1011197. [PMID: 39012914 PMCID: PMC11280534 DOI: 10.1371/journal.pgen.1011197] [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] [Received: 02/25/2024] [Revised: 07/26/2024] [Accepted: 06/27/2024] [Indexed: 07/18/2024] Open
Abstract
We report here the successful labelling of meiotic prophase I DNA synthesis in the flowering plant, Arabidopsis thaliana. Incorporation of the thymidine analogue, EdU, enables visualisation of the footprints of recombinational repair of programmed meiotic DNA double-strand breaks (DSB), with ~400 discrete, SPO11-dependent, EdU-labelled chromosomal foci clearly visible at pachytene and later stages of meiosis. This number equates well with previous estimations of 200-300 DNA double-strand breaks per meiosis in Arabidopsis, confirming the power of this approach to detect the repair of most or all SPO11-dependent meiotic DSB repair events. The chromosomal distribution of these DNA-synthesis foci accords with that of early recombination markers and MLH1, which marks Class I crossover sites. Approximately 10 inter-homologue cross-overs (CO) have been shown to occur in each Arabidopsis male meiosis and, athough very probably under-estimated, an equivalent number of inter-homologue gene conversions (GC) have been described. Thus, at least 90% of meiotic recombination events, and very probably more, have not previously been accessible for analysis. Visual examination of the patterns of the foci on the synapsed pachytene chromosomes corresponds well with expectations from the different mechanisms of meiotic recombination and notably, no evidence for long Break-Induced Replication DNA synthesis tracts was found. Labelling of meiotic prophase I, SPO11-dependent DNA synthesis holds great promise for further understanding of the molecular mechanisms of meiotic recombination, at the heart of reproduction and evolution of eukaryotes.
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Affiliation(s)
- Miguel Hernández Sánchez-Rebato
- Institut de Génétique, Reproduction et Développement, CNRS UMR 6293, INSERM U1103, Université Clermont Auvergne, Clermont-Ferrand, France
| | - Veit Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) Gatersleben, Seeland, Germany
| | - Charles I. White
- Institut de Génétique, Reproduction et Développement, CNRS UMR 6293, INSERM U1103, Université Clermont Auvergne, Clermont-Ferrand, France
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3
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Yang Y, Wang N, Liu G, Nan W, Wang B, Gartner A, Zhang H, Hong Y. COSA-1 mediated pro-crossover complex formation promotes meiotic crossing over in C. elegans. Nucleic Acids Res 2024; 52:4375-4392. [PMID: 38412290 PMCID: PMC11077092 DOI: 10.1093/nar/gkae130] [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] [Received: 09/01/2023] [Revised: 02/03/2024] [Accepted: 02/11/2024] [Indexed: 02/29/2024] Open
Abstract
Accurate chromosome segregation during meiosis requires the establishment of at least one crossover (CO) between each pair of homologous chromosomes. CO formation depends on a group of conserved pro-CO proteins, which colocalize at CO-designated sites during late meiotic prophase I. However, it remains unclear whether these pro-CO proteins form a functional complex and how they promote meiotic CO formation in vivo. Here, we show that COSA-1, a key component required for CO formation, interacts with other pro-CO factors, MSH-5 and ZHP-3, via its N-terminal disordered region. Point mutations that impair these interactions do not affect CO designation, but they strongly hinder the accumulation of COSA-1 at CO-designated sites and result in defective CO formation. These defects can be partially bypassed by artificially tethering an interaction-compromised COSA-1 derivate to ZHP-3. Furthermore, we revealed that the accumulation of COSA-1 into distinct foci is required to assemble functional 'recombination nodules'. These prevent early CO-designated recombination intermediates from being dismantled by the RTEL-1 helicase and protect late recombination intermediates, such as Holliday junctions, until they are resolved by CO-specific resolvases. Altogether, our findings provide insight into COSA-1 mediated pro-CO complex assembly and its contribution to CO formation.
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Affiliation(s)
- Yuejun Yang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Nan Wang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Guoteng Liu
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Wencong Nan
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Bin Wang
- National Key Laboratory of Non-food Biomass and Enzyme Technology, Guangxi Academy of Sciences, Nanning, China
| | - Anton Gartner
- Institute for Basic Sciences Center for Genomic Integrity, Graduate School for Health Sciences and Technology and Department for Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hongtao Zhang
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
| | - Ye Hong
- Shandong Provincial Key Laboratory of Animal Cell and Developmental Biology, School of Life Sciences, Shandong University, Qingdao, Shandong 266237, China
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4
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Lascarez-Lagunas LI, Martinez-Garcia M, Nadarajan S, Diaz-Pacheco BN, Berson E, Colaiácovo MP. Chromatin landscape, DSB levels, and cKU-70/80 contribute to patterning of meiotic DSB processing along chromosomes in C. elegans. PLoS Genet 2023; 19:e1010627. [PMID: 36706157 PMCID: PMC9907818 DOI: 10.1371/journal.pgen.1010627] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 02/08/2023] [Accepted: 01/20/2023] [Indexed: 01/28/2023] Open
Abstract
Programmed DNA double-strand break (DSB) formation is essential for achieving accurate chromosome segregation during meiosis. DSB repair timing and template choice are tightly regulated. However, little is known about how DSB distribution and the choice of repair pathway are regulated along the length of chromosomes, which has direct effects on the recombination landscape and chromosome remodeling at late prophase I. Here, we use the spatiotemporal resolution of meiosis in the Caenorhabditis elegans germline along with genetic approaches to study distribution of DSB processing and its regulation. High-resolution imaging of computationally straightened chromosomes immunostained for the RAD-51 recombinase marking DSB repair sites reveals that the pattern of RAD-51 foci throughout pachytene resembles crossover distribution in wild type. Specifically, RAD-51 foci occur primarily along the gene-poor distal thirds of the chromosomes in both early and late pachytene, and on both the X and the autosomes. However, this biased off-center distribution can be abrogated by the formation of excess DSBs. Reduced condensin function, but not an increase in total physical axial length, results in a homogeneous distribution of RAD-51 foci, whereas regulation of H3K9 methylation is required for the enrichment of RAD-51 at off-center positions. Finally, the DSB recognition heterodimer cKU-70/80, but not the non-homologous end-joining canonical ligase LIG-4, contributes to the enriched off-center distribution of RAD-51 foci. Taken together, our data supports a model by which regulation of the chromatin landscape, DSB levels, and DSB detection by cKU-70/80 collaborate to promote DSB processing by homologous recombination at off-center regions of the chromosomes in C. elegans.
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Affiliation(s)
- Laura I. Lascarez-Lagunas
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marina Martinez-Garcia
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Saravanapriah Nadarajan
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Brianna N. Diaz-Pacheco
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Elizaveta Berson
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Mónica P. Colaiácovo
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America
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5
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Ziesel A, Weng Q, Ahuja JS, Bhattacharya A, Dutta R, Cheng E, Börner GV, Lichten M, Hollingsworth NM. Rad51-mediated interhomolog recombination during budding yeast meiosis is promoted by the meiotic recombination checkpoint and the conserved Pif1 helicase. PLoS Genet 2022; 18:e1010407. [PMID: 36508468 PMCID: PMC9779700 DOI: 10.1371/journal.pgen.1010407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 12/22/2022] [Accepted: 11/16/2022] [Indexed: 12/14/2022] Open
Abstract
During meiosis, recombination between homologous chromosomes (homologs) generates crossovers that promote proper segregation at the first meiotic division. Recombination is initiated by Spo11-catalyzed DNA double strand breaks (DSBs). 5' end resection of the DSBs creates 3' single strand tails that two recombinases, Rad51 and Dmc1, bind to form presynaptic filaments that search for homology, mediate strand invasion and generate displacement loops (D-loops). D-loop processing then forms crossover and non-crossover recombinants. Meiotic recombination occurs in two temporally distinct phases. During Phase 1, Rad51 is inhibited and Dmc1 mediates the interhomolog recombination that promotes homolog synapsis. In Phase 2, Rad51 becomes active and functions with Rad54 to repair residual DSBs, making increasing use of sister chromatids. The transition from Phase 1 to Phase 2 is controlled by the meiotic recombination checkpoint through the meiosis-specific effector kinase Mek1. This work shows that constitutive activation of Rad51 in Phase 1 results in a subset of DSBs being repaired by a Rad51-mediated interhomolog recombination pathway that is distinct from that of Dmc1. Strand invasion intermediates generated by Rad51 require more time to be processed into recombinants, resulting in a meiotic recombination checkpoint delay in prophase I. Without the checkpoint, Rad51-generated intermediates are more likely to involve a sister chromatid, thereby increasing Meiosis I chromosome nondisjunction. This Rad51 interhomolog recombination pathway is specifically promoted by the conserved 5'-3' helicase PIF1 and its paralog, RRM3 and requires Pif1 helicase activity and its interaction with PCNA. This work demonstrates that (1) inhibition of Rad51 during Phase 1 is important to prevent competition with Dmc1 for DSB repair, (2) Rad51-mediated meiotic recombination intermediates are initially processed differently than those made by Dmc1, and (3) the meiotic recombination checkpoint provides time during prophase 1 for processing of Rad51-generated recombination intermediates.
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Affiliation(s)
- Andrew Ziesel
- Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Qixuan Weng
- Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Jasvinder S. Ahuja
- Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Abhishek Bhattacharya
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio, United States of America
| | - Raunak Dutta
- Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - Evan Cheng
- Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
| | - G. Valentin Börner
- Center for Gene Regulation in Health and Disease and Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio, United States of America
| | - Michael Lichten
- Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Nancy M. Hollingsworth
- Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, United States of America
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6
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Lorenz A, Mpaulo SJ. Gene conversion: a non-Mendelian process integral to meiotic recombination. Heredity (Edinb) 2022; 129:56-63. [PMID: 35393552 PMCID: PMC9273591 DOI: 10.1038/s41437-022-00523-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 03/01/2022] [Accepted: 03/02/2022] [Indexed: 12/30/2022] Open
Abstract
Meiosis is undoubtedly the mechanism that underpins Mendelian genetics. Meiosis is a specialised, reductional cell division which generates haploid gametes (reproductive cells) carrying a single chromosome complement from diploid progenitor cells harbouring two chromosome sets. Through this process, the hereditary material is shuffled and distributed into haploid gametes such that upon fertilisation, when two haploid gametes fuse, diploidy is restored in the zygote. During meiosis the transient physical connection of two homologous chromosomes (one originally inherited from each parent) each consisting of two sister chromatids and their subsequent segregation into four meiotic products (gametes), is what enables genetic marker assortment forming the core of Mendelian laws. The initiating events of meiotic recombination are DNA double-strand breaks (DSBs) which need to be repaired in a certain way to enable the homologous chromosomes to find each other. This is achieved by DSB ends searching for homologous repair templates and invading them. Ultimately, the repair of meiotic DSBs by homologous recombination physically connects homologous chromosomes through crossovers. These physical connections provided by crossovers enable faithful chromosome segregation. That being said, the DSB repair mechanism integral to meiotic recombination also produces genetic transmission distortions which manifest as postmeiotic segregation events and gene conversions. These processes are non-reciprocal genetic exchanges and thus non-Mendelian.
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Affiliation(s)
- Alexander Lorenz
- Institute of Medical Sciences (IMS), University of Aberdeen, Aberdeen, UK.
| | - Samantha J Mpaulo
- Institute of Medical Sciences (IMS), University of Aberdeen, Aberdeen, UK
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7
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Pradhan RK, Ramakrishna W. Transposons: Unexpected players in cancer. Gene 2022; 808:145975. [PMID: 34592349 DOI: 10.1016/j.gene.2021.145975] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 09/19/2021] [Accepted: 09/24/2021] [Indexed: 12/21/2022]
Abstract
Transposons are repetitive DNA sequences encompassing about half of the human genome. They play a vital role in genome stability maintenance and contribute to genomic diversity and evolution. Their activity is regulated by various mechanisms considering the deleterious effects of these mobile elements. Various genetic risk factors and environmental stress conditions affect the regulatory pathways causing alteration of transposon expression. Our knowledge of the biological role of transposons is limited especially in various types of cancers. Retrotransposons of different types (LTR-retrotransposons, LINEs and SINEs) regulate a plethora of genes that have a role in cell reprogramming, tumor suppression, cell cycle, apoptosis, cell adhesion and migration, and DNA repair. The regulatory mechanisms of transposons, their deregulation and different mechanisms underlying transposon-mediated carcinogenesis in humans focusing on the three most prevalent types, lung, breast and colorectal cancers, were reviewed. The modes of regulation employed include alternative splicing, deletion, insertion, duplication in genes and promoters resulting in upregulation, downregulation or silencing of genes.
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8
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Imai Y, Olaya I, Sakai N, Burgess SM. Meiotic Chromosome Dynamics in Zebrafish. Front Cell Dev Biol 2021; 9:757445. [PMID: 34692709 PMCID: PMC8531508 DOI: 10.3389/fcell.2021.757445] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 09/14/2021] [Indexed: 11/13/2022] Open
Abstract
Recent studies in zebrafish have revealed key features of meiotic chromosome dynamics, including clustering of telomeres in the bouquet configuration, biogenesis of chromosome axis structures, and the assembly and disassembly of the synaptonemal complex that aligns homologs end-to-end. The telomere bouquet stage is especially pronounced in zebrafish meiosis and sub-telomeric regions play key roles in mediating pairing and homologous recombination. In this review, we discuss the temporal progression of these events in meiosis prophase I and highlight the roles of proteins associated with meiotic chromosome architecture in homologous recombination. Finally, we discuss the interplay between meiotic mutants and gonadal sex differentiation and future research directions to study meiosis in living cells, including cell culture.
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Affiliation(s)
- Yukiko Imai
- Department of Gene Function and Phenomics, National Institute of Genetics, Mishima, Japan
| | - Ivan Olaya
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States.,Integrative Genetics and Genomics Graduate Group, University of California, Davis, Davis, CA, United States
| | - Noriyoshi Sakai
- Department of Gene Function and Phenomics, National Institute of Genetics, Mishima, Japan.,Department of Genetics, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies), Mishima, Japan
| | - Sean M Burgess
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA, United States
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9
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Toraason E, Glover M, Horacek A, Libuda DE. Detection of homolog-independent meiotic DNA repair events in C. elegans with the intersister/intrachromatid repair assay. STAR Protoc 2021; 2:100801. [PMID: 34527958 PMCID: PMC8433254 DOI: 10.1016/j.xpro.2021.100801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Accurate repair of DNA double-strand breaks (DSBs) in developing germ cells is critical to promote proper chromosome segregation and to maintain genome integrity. To directly detect homolog-independent (intersister/intrachromatid) meiotic DSB repair, we exploited the genetics and germline physiology of C. elegans to (1) induce a single DSB in nuclei across discrete stages of meiotic prophase I; (2) detect repair of that DSB as a homolog-independent crossover or noncrossover; and (3) sequence the resultant product to assess mechanisms of recombination. For complete details on the use and execution of this protocol, please refer to Toraason et al. (2021).
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Affiliation(s)
- Erik Toraason
- Institute of Molecular Biology, Department of Biology, University of Oregon, 1229 Franklin Boulevard, Eugene, OR 97403, USA
| | - Marissa Glover
- Institute of Molecular Biology, Department of Biology, University of Oregon, 1229 Franklin Boulevard, Eugene, OR 97403, USA
- Department of Molecular, Cell, and Developmental Biology, University of California Santa Cruz, Sinsheimer Labs, 1156 High Street, Santa Cruz, CA 95064, USA
| | - Anna Horacek
- Institute of Molecular Biology, Department of Biology, University of Oregon, 1229 Franklin Boulevard, Eugene, OR 97403, USA
- Section on Gene Expression, Eunice Kennedy Shriver National Institute of Child Health and Human Development, P.O. Box 3006, Rockville, MD 20847, USA
| | - Diana E. Libuda
- Institute of Molecular Biology, Department of Biology, University of Oregon, 1229 Franklin Boulevard, Eugene, OR 97403, USA
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10
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Beverley R, Snook ML, Brieño-Enríquez MA. Meiotic Cohesin and Variants Associated With Human Reproductive Aging and Disease. Front Cell Dev Biol 2021; 9:710033. [PMID: 34409039 PMCID: PMC8365356 DOI: 10.3389/fcell.2021.710033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 07/13/2021] [Indexed: 12/19/2022] Open
Abstract
Successful human reproduction relies on the well-orchestrated development of competent gametes through the process of meiosis. The loading of cohesin, a multi-protein complex, is a key event in the initiation of mammalian meiosis. Establishment of sister chromatid cohesion via cohesin rings is essential for ensuring homologous recombination-mediated DNA repair and future proper chromosome segregation. Cohesin proteins loaded during female fetal life are not replenished over time, and therefore are a potential etiology of age-related aneuploidy in oocytes resulting in decreased fecundity and increased infertility and miscarriage rates with advancing maternal age. Herein, we provide a brief overview of meiotic cohesin and summarize the human genetic studies which have identified genetic variants of cohesin proteins and the associated reproductive phenotypes including primary ovarian insufficiency, trisomy in offspring, and non-obstructive azoospermia. The association of cohesion defects with cancer predisposition and potential impact on aging are also described. Expansion of genetic testing within clinical medicine, with a focus on cohesin protein-related genes, may provide additional insight to previously unknown etiologies of disorders contributing to gamete exhaustion in females, and infertility and reproductive aging in both men and women.
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Affiliation(s)
- Rachel Beverley
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Meredith L Snook
- Division of Reproductive Endocrinology and Infertility, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA, United States
| | - Miguel Angel Brieño-Enríquez
- Magee-Womens Research Institute, Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Pittsburgh, Pittsburgh, PA, United States
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11
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Abstract
The formation of crossovers between homologous chromosomes is key to sexual reproduction. In most species, crossovers are spaced further apart than would be expected if they formed independently, a phenomenon termed crossover interference. Despite more than a century of study, the molecular mechanisms implementing crossover interference remain a subject of active debate. Recent findings of how signaling proteins control the formation of crossovers and about the interchromosomal interface in which crossovers form offer new insights into this process. In this Review, we present a cell biological and biophysical perspective on crossover interference, summarizing the evidence that links interference to the spatial, dynamic, mechanical and molecular properties of meiotic chromosomes. We synthesize this physical understanding in the context of prevailing mechanistic models that aim to explain how crossover interference is implemented.
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Affiliation(s)
- Lexy von Diezmann
- Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA.,School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Ofer Rog
- Center for Cell and Genome Sciences, University of Utah, Salt Lake City, UT 84112, USA.,School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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12
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Abstract
Meiotic double-strand break repair is a highly regulated process usually occurring between homologs. Assessing repair in metazoans using the sister chromatid has previously been technically challenging. Two new studies show that, while rare, sister chromatid repair occurs in Caenorhabditis elegans.
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Affiliation(s)
| | - Stacie E Hughes
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA.
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13
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Almanzar DE, Gordon SG, Rog O. Meiotic sister chromatid exchanges are rare in C. elegans. Curr Biol 2021; 31:1499-1507.e3. [PMID: 33740426 PMCID: PMC8051885 DOI: 10.1016/j.cub.2020.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/08/2020] [Accepted: 11/05/2020] [Indexed: 11/16/2022]
Abstract
Sexual reproduction shuffles the parental genomes to generate new genetic combinations. To achieve that, the genome is subjected to numerous double-strand breaks, the repair of which involves two crucial decisions: repair pathway and repair template.1 Use of crossover pathways with the homologous chromosome as template exchanges genetic information and directs chromosome segregation. Crossover repair, however, can compromise the integrity of the repair template and is therefore tightly regulated. The extent to which crossover pathways are used during sister-directed repair is unclear because the identical sister chromatids are difficult to distinguish. Nonetheless, indirect assays have led to the suggestion that inter-sister crossovers, or sister chromatid exchanges (SCEs), are quite common.2-11 Here we devised a technique to directly score physiological SCEs in the C. elegans germline using selective sister chromatid labeling with the thymidine analog 5-ethynyl-2'-deoxyuridine (EdU). Surprisingly, we find SCEs to be rare in meiosis, accounting for <2% of repair events. SCEs remain rare even when the homologous chromosome is unavailable, indicating that almost all sister-directed repair is channeled into noncrossover pathways. We identify two mechanisms that limit SCEs. First, SCEs are elevated in the absence of the RecQ helicase BLMHIM-6. Second, the synaptonemal complex-a conserved interface that promotes crossover repair12,13-promotes SCEs when localized between the sisters. Our data suggest that crossover pathways in C. elegans are only used to generate the single necessary link between the homologous chromosomes. Noncrossover pathways repair almost all other breaks, regardless of the repair template.
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Affiliation(s)
- David E Almanzar
- School of Biological Sciences, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, USA
| | - Spencer G Gordon
- School of Biological Sciences, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, USA
| | - Ofer Rog
- School of Biological Sciences, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, USA.
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