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Annual Review of Genomics and Human... Aug 2023In meiosis, homologous chromosome synapsis is mediated by a supramolecular protein structure, the synaptonemal complex (SC), that assembles between homologous chromosome... (Review)
Review
In meiosis, homologous chromosome synapsis is mediated by a supramolecular protein structure, the synaptonemal complex (SC), that assembles between homologous chromosome axes. The mammalian SC comprises at least eight largely coiled-coil proteins that interact and self-assemble to generate a long, zipper-like structure that holds homologous chromosomes in close proximity and promotes the formation of genetic crossovers and accurate meiotic chromosome segregation. In recent years, numerous mutations in human SC genes have been associated with different types of male and female infertility. Here, we integrate structural information on the human SC with mouse and human genetics to describe the molecular mechanisms by which SC mutations can result in human infertility. We outline certain themes in which different SC proteins are susceptible to different types of disease mutation and how genetic variants with seemingly minor effects on SC proteins may act as dominant-negative mutations in which the heterozygous state is pathogenic.
Topics: Male; Female; Humans; Mice; Animals; Synaptonemal Complex; Chromosome Pairing; Meiosis; Infertility; Mutation; Mammals
PubMed: 37159901
DOI: 10.1146/annurev-genom-110122-090239 -
Centrosome linker diversity and its function in centrosome clustering and mitotic spindle formation.The EMBO Journal Sep 2023The centrosome linker joins the two interphase centrosomes of a cell into one microtubule organizing center. Despite increasing knowledge on linker components, linker...
The centrosome linker joins the two interphase centrosomes of a cell into one microtubule organizing center. Despite increasing knowledge on linker components, linker diversity in different cell types and their role in cells with supernumerary centrosomes remained unexplored. Here, we identified Ninein as a C-Nap1-anchored centrosome linker component that provides linker function in RPE1 cells while in HCT116 and U2OS cells, Ninein and Rootletin link centrosomes together. In interphase, overamplified centrosomes use the linker for centrosome clustering, where Rootletin gains centrosome linker function in RPE1 cells. Surprisingly, in cells with centrosome overamplification, C-Nap1 loss prolongs metaphase through persistent activation of the spindle assembly checkpoint indicated by BUB1 and MAD1 accumulation at kinetochores. In cells lacking C-Nap1, the reduction of microtubule nucleation at centrosomes and the delay in nuclear envelop rupture in prophase probably cause mitotic defects like multipolar spindle formation and chromosome mis-segregation. These defects are enhanced when the kinesin HSET, which normally clusters multiple centrosomes in mitosis, is partially inhibited indicating a functional interplay between C-Nap1 and centrosome clustering in mitosis.
Topics: Centrosome; Cell Cycle; Cell Cycle Proteins; Interphase; Mitosis; Spindle Apparatus
PubMed: 37401899
DOI: 10.15252/embj.2021109738 -
BioEssays : News and Reviews in... Oct 2023The ovarian reserve defines female reproductive lifespan, which in humans spans decades. The ovarian reserve consists of oocytes residing in primordial follicles...
The ovarian reserve defines female reproductive lifespan, which in humans spans decades. The ovarian reserve consists of oocytes residing in primordial follicles arrested in meiotic prophase I and is maintained independent of DNA replication and cell proliferation, thereby lacking stem cell-based maintenance. Largely unknown is how cellular states of the ovarian reserve are established and maintained for decades. Our recent study revealed that a distinct chromatin state is established during ovarian reserve formation in mice, uncovering a novel window of epigenetic programming in female germline development. We showed that an epigenetic regulator, Polycomb Repressive Complex 1 (PRC1), establishes a repressive chromatin state in perinatal mouse oocytes that is essential for prophase I-arrested oocytes to form the ovarian reserve. Here we discuss the biological roles and mechanisms underlying epigenetic programming in ovarian reserve formation, highlighting current knowledge gaps and emerging research areas in female reproductive biology.
Topics: Humans; Pregnancy; Female; Mice; Animals; Meiosis; Ovarian Reserve; Oocytes; Chromatin; Epigenesis, Genetic
PubMed: 37417392
DOI: 10.1002/bies.202300069 -
Mathematical Biosciences May 2024This paper develops a theory for anaphase in cells. After a brief description of microtubules, the mitotic spindle and the centrosome, a mathematical model for anaphase...
This paper develops a theory for anaphase in cells. After a brief description of microtubules, the mitotic spindle and the centrosome, a mathematical model for anaphase is introduced and developed in the context of the cell cytoplasm and liquid crystalline structures. Prophase, prometaphase and metaphase are then briefly described in order to focus on anaphase, which is the main study of this paper. The entities involved are modelled in terms of liquid crystal defects and microtubules are represented as defect flux lines. The mathematical techniques employed make extensive use of energy considerations based on the work that was developed by Dafermos (1970) from the classical Frank-Oseen nematic liquid crystal energy (Frank, 1958; Oseen, 1933). With regard to liquid crystal theory we introduce the concept of regions of influence for defects which it is believed have important implications beyond the subject of this paper. The results of this paper align with observed biochemical phenomena and are explored in application to HeLa cells and Caenorhabditis elegans. This unified approach offers the possibility of gaining insight into various consequences of mitotic abnormalities which may result in Down syndrome, Hodgkin lymphoma, breast, prostate and various other types of cancer.
PubMed: 38795952
DOI: 10.1016/j.mbs.2024.109219 -
PLoS Genetics Nov 2023The centromere is an epigenetic mark that is a loading site for the kinetochore during meiosis and mitosis. This mark is characterized by the H3 variant CENP-A, known as...
The centromere is an epigenetic mark that is a loading site for the kinetochore during meiosis and mitosis. This mark is characterized by the H3 variant CENP-A, known as CID in Drosophila. In Drosophila, CENP-C is critical for maintaining CID at the centromeres and directly recruits outer kinetochore proteins after nuclear envelope break down. These two functions, however, happen at different times in the cell cycle. Furthermore, in Drosophila and many other metazoan oocytes, centromere maintenance and kinetochore assembly are separated by an extended prophase. We have investigated the dynamics of function of CENP-C during the extended meiotic prophase of Drosophila oocytes and found that maintaining high levels of CENP-C for metaphase I requires expression during prophase. In contrast, CID is relatively stable and does not need to be expressed during prophase to remain at high levels in metaphase I of meiosis. Expression of CID during prophase can even be deleterious, causing ectopic localization to non-centromeric chromatin, abnormal meiosis and sterility. CENP-C prophase loading is required for multiple meiotic functions. In early meiotic prophase, CENP-C loading is required for sister centromere cohesion and centromere clustering. In late meiotic prophase, CENP-C loading is required to recruit kinetochore proteins. CENP-C is one of the few proteins identified in which expression during prophase is required for meiotic chromosome segregation. An implication of these results is that the failure to maintain recruitment of CENP-C during the extended prophase in oocytes would result in chromosome segregation errors in oocytes.
Topics: Animals; Meiosis; Chromosome Segregation; Drosophila Proteins; Prophase; Centromere; Drosophila; Mitosis; Kinetochores; Centromere Protein A; Chromosomal Proteins, Non-Histone
PubMed: 38019881
DOI: 10.1371/journal.pgen.1011066 -
Nature Communications Oct 2023The formation of RAD51/DMC1 filaments on single-stranded (ss)DNAs essential for homology search and strand exchange in DNA double-strand break (DSB) repair is tightly...
The formation of RAD51/DMC1 filaments on single-stranded (ss)DNAs essential for homology search and strand exchange in DNA double-strand break (DSB) repair is tightly regulated. FIGNL1 AAA+++ ATPase controls RAD51-mediated recombination in human cells. However, its role in gametogenesis remains unsolved. Here, we characterized a germ line-specific conditional knockout (cKO) mouse of FIGNL1. Fignl1 cKO male mice showed defective chromosome synapsis and impaired meiotic DSB repair with the accumulation of RAD51/DMC1 on meiotic chromosomes, supporting a positive role of FIGNL1 in homologous recombination at a post-assembly stage of RAD51/DMC1 filaments. Fignl1 cKO spermatocytes also accumulate RAD51/DMC1 on chromosomes in pre-meiotic S-phase. These RAD51/DMC1 assemblies are independent of meiotic DSB formation. We also showed that purified FIGNL1 dismantles RAD51 filament on double-stranded (ds)DNA as well as ssDNA. These results suggest an additional role of FIGNL1 in limiting the non-productive assembly of RAD51/DMC1 on native dsDNAs during pre-meiotic S-phase and meiotic prophase I.
Topics: Male; Humans; Animals; Mice; Meiosis; Rad51 Recombinase; DNA-Binding Proteins; ATPases Associated with Diverse Cellular Activities; DNA Breaks, Double-Stranded; Cell Cycle Proteins; Homologous Recombination; DNA; DNA Replication; Microtubule-Associated Proteins; Nuclear Proteins
PubMed: 37891173
DOI: 10.1038/s41467-023-42576-w -
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 -
Cell Proliferation Apr 2024The successful progression of meiosis prophase I requires integrating information from the structural and molecular levels. In this study, we show that ZFP541 and KCTD19...
The successful progression of meiosis prophase I requires integrating information from the structural and molecular levels. In this study, we show that ZFP541 and KCTD19 work in the same genetic pathway to regulate the progression of male meiosis and thus fertility. The Zfp541 and/or Kctd19 knockout male mice show various structural and recombination defects including detached chromosome ends, aberrant localization of chromosome axis components and recombination proteins, and globally altered histone modifications. Further analyses on RNA-seq, ChIP-seq, and ATAC-seq data provide molecular evidence for the above defects and reveal that ZFP541/KCTD19 activates the expression of many genes by repressing several major transcription repressors. More importantly, we reveal an unexpected role of ZFP541/KCTD19 in directly modulating chromatin organization. These results suggest that ZFP541/KCTD19 simultaneously regulates the transcription cascade and chromatin organization to ensure the coordinated progression of multiple events at chromosome structural and biochemical levels during meiosis prophase I.
Topics: Animals; Mice; Male; Chromatin; Transcription Factors; Synaptonemal Complex; Protein Processing, Post-Translational; Meiosis; Chromosomal Proteins, Non-Histone
PubMed: 37921559
DOI: 10.1111/cpr.13567 -
The British Journal of Psychiatry : the... Jul 2023Early-onset psychosis (EOP) refers to the development of a first episode of psychosis before 18 years of age. Individuals at clinical high risk for psychosis (CHR-P)... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Early-onset psychosis (EOP) refers to the development of a first episode of psychosis before 18 years of age. Individuals at clinical high risk for psychosis (CHR-P) include adolescents and young adults, although most evidence has focused on adults. Negative symptoms are important prognostic indicators in psychosis. However, research focusing on children and adolescents is limited.
AIMS
To provide meta-analytical evidence and a comprehensive review of the status and advances in the diagnosis, prognosis and treatment of negative symptoms in children and adolescents with EOP and at CHR-P.
METHOD
PRISMA/MOOSE-compliant systematic review (PROSPERO: CRD42022360925) from inception to 18 August 2022, in any language, to identify individual studies conducted in EOP/CHR-P children and adolescents (mean age <18 years) providing findings on negative symptoms. Findings were systematically appraised. Random-effects meta-analyses were performed on the prevalence of negative symptoms, carrying out sensitivity analyses, heterogeneity analyses, publication bias assessment and quality assessment using the Newcastle-Ottawa Scale.
RESULTS
Of 3289 articles, 133 were included ( = 6776 EOP, mean age 15.3 years (s.d. = 1.6), males = 56.1%; = 2138 CHR-P, mean age 16.1 years (s.d. = 1.0), males = 48.6%). There were negative symptoms in 60.8% (95% CI 46.4%-75.2%) of the children and adolescents with EOP and 79.6% (95% CI 66.3-92.9%) of those at CHR-P. Prevalence and severity of negative symptoms were associated with poor clinical, functional and intervention outcomes in both groups. Different interventions were piloted, with variable results requiring further replication.
CONCLUSIONS
Negative symptoms are common in children and adolescents at early stages of psychosis, particularly in those at CHR-P, and are associated with poor outcomes. Future intervention research is required so that evidence-based treatments will become available.
Topics: Male; Humans; Child; Psychotic Disorders; Prognosis
PubMed: 37194556
DOI: 10.1192/bjp.2022.203 -
Vavilovskii Zhurnal Genetiki I Selektsii Oct 2023Germline-restricted chromosomes (GRCs) are present in the genomes of germline cells and absent from somatic cells. A GRC is found in all species of the songbirds...
Germline-restricted chromosomes (GRCs) are present in the genomes of germline cells and absent from somatic cells. A GRC is found in all species of the songbirds (Passeri) and in none of the other bird orders studied to date. This indicates that GRC originated in the common ancestor of the songbirds. The germline-restricted chromosome is permanently absent from somatic cells of the songbird, while female germline cells usually contain two copies of GRC and male ones have one copy. In females, GRCs undergo synapsis and restricted recombination in their terminal regions during meiotic prophase. In males, it is almost always eliminated from spermatocytes. Thus, GRC is inherited almost exclusively through the maternal lineage. The germline-restricted chromosome is a necessary genomic element in the germline cells of songbirds. To date, the GRC genetic composition has been studied in four species only. Some GRC genes are actively expressed in female and male gonads, controlling the development of germline cells and synthesis of the proteins involved in the organization of meiotic chromosomes. Songbird species vary in GRC size and genetic composition. The GRC of each bird species consists of amplified and modified copies of genes from the basic genome of that species. The level of homology between GRCs of different species is relatively low, indicating a high rate of genetic evolution of this chromosome. Transmission through the maternal lineage and suppression of the recombination contribute significantly to the accelerated evolution of GRCs. One may suggest that the rapid coordinated evolution between the GRC genes and the genes of the basic genome in the songbirds might be responsible for the explosive speciation and adaptive radiation of this most species-rich and diverse infraorder of birds.
PubMed: 38023808
DOI: 10.18699/VJGB-23-75