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Genes To Cells : Devoted To Molecular &... Jan 2019Cohesin is an evolutionary conserved multi-protein complex that plays a pivotal role in chromosome dynamics. It plays a role both in sister chromatid cohesion and in... (Review)
Review
Cohesin is an evolutionary conserved multi-protein complex that plays a pivotal role in chromosome dynamics. It plays a role both in sister chromatid cohesion and in establishing higher order chromosome architecture, in somatic and germ cells. Notably, the cohesin complex in meiosis differs from that in mitosis. In mammalian meiosis, distinct types of cohesin complexes are produced by altering the combination of meiosis-specific subunits. The meiosis-specific subunits endow the cohesin complex with specific functions for numerous meiosis-associated chromosomal events, such as chromosome axis formation, homologue association, meiotic recombination and centromeric cohesion for sister kinetochore geometry. This review mainly focuses on the cohesin complex in mammalian meiosis, pointing out the differences in its roles from those in mitosis. Further, common and divergent aspects of the meiosis-specific cohesin complex between mammals and other organisms are discussed.
Topics: Animals; Cell Cycle Proteins; Chromosomal Proteins, Non-Histone; Chromosome Pairing; Chromosomes, Mammalian; Mammals; Meiosis; Mitosis; Cohesins
PubMed: 30479058
DOI: 10.1111/gtc.12652 -
Asian Journal of Andrology 2021
Topics: Humans; Meiosis; Mitosis
PubMed: 34708720
DOI: 10.4103/aja202192 -
Journal of Molecular Cell Biology Sep 2022Meiosis is essential for evolution and genetic diversity in almost all sexual eukaryotic organisms. The mechanisms of meiotic recombination, such as synapsis, have been...
Meiosis is essential for evolution and genetic diversity in almost all sexual eukaryotic organisms. The mechanisms of meiotic recombination, such as synapsis, have been extensively investigated. However, it is still unclear whether signals from the cytoplasm or even from outside of the cell can regulate the meiosis process. Cilia are microtubule-based structures that protrude from the cell surface and function as signaling hubs to sense extracellular signals. Here, we reported an unexpected and critical role of cilia during meiotic recombination. During gametogenesis of zebrafish, cilia were specifically present in the prophase stages of both primary spermatocytes and primary oocytes. By developing a germ cell-specific CRISPR/Cas9 system, we demonstrated that germ cell-specific depletion of ciliary genes resulted in compromised double-strand break repair, reduced crossover formation, and increased germ cell apoptosis. Our study reveals a previously undiscovered role for cilia during meiosis and suggests that extracellular signals may regulate meiotic recombination via this particular organelle.
Topics: Animals; Male; Zebrafish; Cilia; Meiosis; Chromosome Pairing; DNA Repair
PubMed: 35981808
DOI: 10.1093/jmcb/mjac049 -
Genetics Oct 2023Meiosis is a specialized cell division program that is essential for sexual reproduction. The two meiotic divisions reduce chromosome number by half, typically...
Meiosis is a specialized cell division program that is essential for sexual reproduction. The two meiotic divisions reduce chromosome number by half, typically generating haploid genomes that are packaged into gametes. To achieve this ploidy reduction, meiosis relies on highly unusual chromosomal processes including the pairing of homologous chromosomes, assembly of the synaptonemal complex, programmed formation of DNA breaks followed by their processing into crossovers, and the segregation of homologous chromosomes during the first meiotic division. These processes are embedded in a carefully orchestrated cell differentiation program with multiple interdependencies between DNA metabolism, chromosome morphogenesis, and waves of gene expression that together ensure the correct number of chromosomes is delivered to the next generation. Studies in the budding yeast Saccharomyces cerevisiae have established essentially all fundamental paradigms of meiosis-specific chromosome metabolism and have uncovered components and molecular mechanisms that underlie these conserved processes. Here, we provide an overview of all stages of meiosis in this key model system and highlight how basic mechanisms of genome stability, chromosome architecture, and cell cycle control have been adapted to achieve the unique outcome of meiosis.
Topics: Recombination, Genetic; Saccharomycetales; Meiosis; Saccharomyces cerevisiae; Synaptonemal Complex
PubMed: 37616582
DOI: 10.1093/genetics/iyad125 -
Biology of Reproduction Nov 2019Oocyte meiotic maturation is a vital and final process in oogenesis. Unlike somatic cells, the oocyte needs to undergo two continuous meiotic divisions (meiosis I and... (Review)
Review
Oocyte meiotic maturation is a vital and final process in oogenesis. Unlike somatic cells, the oocyte needs to undergo two continuous meiotic divisions (meiosis I and meiosis II) to become a haploid gamete. Notably, oocyte meiotic progression includes two rounds of unique meiotic arrest and resumption. The first arrest occurs at the G2 (germinal vesicle) stage and meiosis resumption is stimulated by a gonadotropin surge; the second arrest takes place at the metaphase II stage, the stage from which it is released when fertilization takes place. The maturation-promoting factor, which consists of cyclin B1 (CCNB1) and cyclin-dependent kinase 1 (CDK1), is responsible for regulating meiotic resumption and progression, while CDK1 is the unique CDK that acts as the catalytic subunit of maturation-promoting factor. Recent studies showed that except for cyclin B1, multiple cyclins interact with CDK1 to form complexes, which are involved in the regulation of meiotic progression at different stages. Here, we review and discuss the control of oocyte meiotic progression by cyclins A1, A2, B1, B2, B3, and O.
Topics: Animals; Cell Cycle; Cyclins; Female; Meiosis; Oocytes
PubMed: 31347666
DOI: 10.1093/biolre/ioz143 -
Current Biology : CB Jun 2019In sexual reproduction, opportunities are limited and the stakes are high. This inevitably leads to conflict. One pervasive conflict occurs within genomes between... (Review)
Review
In sexual reproduction, opportunities are limited and the stakes are high. This inevitably leads to conflict. One pervasive conflict occurs within genomes between alternative alleles at heterozygous loci. Each gamete and thus each offspring will inherit only one of the two alleles from a heterozygous parent. Most alleles 'play fair' and have a 50% chance of being included in any given gamete. However, alleles can gain an enormous advantage if they act selfishly to force their own transmission into more than half, sometimes even all, of the functional gametes. These selfish alleles are known as 'meiotic drivers', and their cheating often incurs a high cost on the fertility of eukaryotes ranging from plants to mammals. Here, we review how several types of meiotic drivers directly and indirectly contribute to infertility, and argue that a complete picture of the genetics of infertility will require focusing on both the standard alleles - those that play fair - as well as selfish alleles involved in genetic conflict.
Topics: Eukaryota; Fertility; Meiosis
PubMed: 31163165
DOI: 10.1016/j.cub.2019.03.046 -
Cells Mar 2020Meiosis is a key event in the manufacturing of an oocyte. During this process, the oocyte creates a set of unique chromosomes by recombining paternal and maternal copies... (Review)
Review
Meiosis is a key event in the manufacturing of an oocyte. During this process, the oocyte creates a set of unique chromosomes by recombining paternal and maternal copies of homologous chromosomes, and by eliminating one set of chromosomes to become haploid. While meiosis is conserved among sexually reproducing eukaryotes, there is a bewildering diversity of strategies among species, and sometimes within sexes of the same species, to achieve proper segregation of chromosomes. Here, we review the very first steps of meiosis in females, when the maternal and paternal copies of each homologous chromosomes have to move, find each other and pair. We explore the similarities and differences observed in , , zebrafish and mouse females.
Topics: Animals; Caenorhabditis elegans; Chromosomes; Meiosis
PubMed: 32178277
DOI: 10.3390/cells9030696 -
Annual Review of Genetics Nov 2021The specialized two-stage meiotic cell division program halves a cell's chromosome complement in preparation for sexual reproduction. This reduction in ploidy requires... (Review)
Review
The specialized two-stage meiotic cell division program halves a cell's chromosome complement in preparation for sexual reproduction. This reduction in ploidy requires that in meiotic prophase, each pair of homologous chromosomes (homologs) identify one another and form physical links through DNA recombination. Here, we review recent advances in understanding the complex morphological changes that chromosomes undergo during meiotic prophase to promote homolog identification and crossing over. We focus on the structural maintenance of chromosomes (SMC) family cohesin complexes and the meiotic chromosome axis, which together organize chromosomes and promote recombination. We then discuss the architecture and dynamics of the conserved synaptonemal complex (SC), which assembles between homologs and mediates local and global feedback to ensure high fidelity in meiotic recombination. Finally, we discuss exciting new advances, including mechanisms for boosting recombination on particular chromosomes or chromosomal domains and the implications of a new liquid crystal model for SC assembly and structure.
Topics: Chromosome Pairing; Chromosomes; Homologous Recombination; Meiosis; Synaptonemal Complex
PubMed: 34530636
DOI: 10.1146/annurev-genet-071719-020235 -
Philosophical Transactions of the Royal... Oct 2016Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features... (Review)
Review
Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often 'weird' features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
Topics: Biological Evolution; Eukaryota; Meiosis; Recombination, Genetic; Sex
PubMed: 27619705
DOI: 10.1098/rstb.2016.0001 -
Asian Journal of Andrology 2021Repairing DNA double-strand breaks (DSBs) with homologous chromosomes as templates is the hallmark of meiosis. The critical outcome of meiotic homologous recombination... (Review)
Review
Repairing DNA double-strand breaks (DSBs) with homologous chromosomes as templates is the hallmark of meiosis. The critical outcome of meiotic homologous recombination is crossovers, which ensure faithful chromosome segregation and promote genetic diversity of progenies. Crossover patterns are tightly controlled and exhibit three characteristics: obligatory crossover, crossover interference, and crossover homeostasis. Aberrant crossover patterns are the leading cause of infertility, miscarriage, and congenital disease. Crossover recombination occurs in the context of meiotic chromosomes, and it is tightly integrated with and regulated by meiotic chromosome structure both locally and globally. Meiotic chromosomes are organized in a loop-axis architecture. Diverse evidence shows that chromosome axis length determines crossover frequency. Interestingly, short chromosomes show different crossover patterns compared to long chromosomes. A high frequency of human embryos are aneuploid, primarily derived from female meiosis errors. Dramatically increased aneuploidy in older women is the well-known "maternal age effect." However, a high frequency of aneuploidy also occurs in young women, derived from crossover maturation inefficiency in human females. In addition, frequency of human aneuploidy also shows other age-dependent alterations. Here, current advances in the understanding of these issues are reviewed, regulation of crossover patterns by meiotic chromosomes are discussed, and issues that remain to be investigated are suggested.
Topics: Cell Division; Chromosome Segregation; Humans; Meiosis; Recombination, Genetic
PubMed: 33533735
DOI: 10.4103/aja.aja_86_20