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FEBS Letters Oct 2019The primary function of cyclin-dependent kinases (CDKs) in complex with their activating cyclin partners is to promote mitotic division in somatic cells. This canonical... (Review)
Review
The primary function of cyclin-dependent kinases (CDKs) in complex with their activating cyclin partners is to promote mitotic division in somatic cells. This canonical cell cycle-associated activity is also crucial for fertility as it allows the proliferation and differentiation of stem cells within the reproductive organs to generate meiotically competent cells. Intriguingly, several CDKs exhibit meiosis-specific functions and are essential for the completion of the two reductional meiotic divisions required to generate haploid gametes. These meiosis-specific functions are mediated by both known CDK/cyclin complexes and meiosis-specific CDK-regulators and are important for a variety of processes during meiotic prophase. The majority of meiotic defects observed upon deletion of these proteins occur during the extended prophase I of the first meiotic division. Importantly a lack of redundancy is seen within the meiotic arrest phenotypes described for many of these proteins, suggesting intricate layers of cell cycle control are required for normal meiotic progression. Using the process of male germ cell development (spermatogenesis) as a reference, this review seeks to highlight the diverse roles of selected CDKs their activators, and their regulators during gametogenesis.
Topics: Animals; Cell Cycle Checkpoints; Cell Differentiation; Cell Proliferation; Cyclin-Dependent Kinases; Cyclins; Gene Expression Regulation; Haploidy; Male; Meiosis; Mice; Nuclear Proteins; Recombination, Genetic; Signal Transduction; Spermatogenesis; Spermatozoa; Stem Cells
PubMed: 31566717
DOI: 10.1002/1873-3468.13627 -
Acta Obstetricia Et Gynecologica... Dec 2019In 2008, Hultén et al hypothesized that maternal ovarian trisomy 21 mosaicism might be the primary causative factor for fetal Down syndrome. We hypothesize that this...
INTRODUCTION
In 2008, Hultén et al hypothesized that maternal ovarian trisomy 21 mosaicism might be the primary causative factor for fetal Down syndrome. We hypothesize that this theory can be extended to trisomy 13.
MATERIAL AND METHODS
We collected fetal ovarian tissue from seven female fetuses between 16 and 23 gestational weeks, following the termination of the pregnancy for non-genetic reasons. All procedures were performed with informed consent and ethical approval from the local ethics committee. We used touch preparation techniques from fetal ovarian tissues and an anti-stromal antigen 3 antibody against the meiosis-specific stromal antigen 3 protein to differentiate between germ cells, ovarian stromal cells and the cells entering their first meiotic prophase. We used fluorescence in situ hybridization analysis to determine chromosome 13 numbers in each cell.
RESULTS
We were able to detect a proportion of trisomy 13 cells in all cases. The average incidence of trisomy 13 cells was 2.04% in stromal antigen 3-positive and 0.91% in the stromal antigen 3-negative cells. The number of the trisomic cells increased significantly with gestational age (for stromal antigen 3-positive cells r = 0.93, P = 0.0038, for stromal antigen 3-negative cells r = 0.85, P = 0.0071).
CONCLUSIONS
This study indicates that besides trisomy 21, the Oocyte Mosaicism Selection model could be extended to trisomy 13 as well. The crucial factor for trisomy 13 seems to be the pre-meiotic/mitotic trisomy 13 mosaicism, leading to a so-called secondary meiotic nondisjunction of those oocytes having three copies of chromosome 13.
Topics: Cell Cycle Proteins; Female; Fetus; Germ Cells; Humans; In Situ Hybridization, Fluorescence; Meiosis; Models, Genetic; Mosaicism; Oocytes; Ovary; Stromal Cells; Trisomy 13 Syndrome
PubMed: 31464342
DOI: 10.1111/aogs.13694 -
Journal of Cell Science Sep 2019High-fidelity chromosome segregation relies on proper microtubule regulation. Kinesin-8 has been shown to destabilise microtubules to reduce metaphase spindle length and...
High-fidelity chromosome segregation relies on proper microtubule regulation. Kinesin-8 has been shown to destabilise microtubules to reduce metaphase spindle length and chromosome movements in multiple species. XMAP215/chTOG polymerases catalyse microtubule growth for spindle assembly, elongation and kinetochore-microtubule attachment. Understanding of their biochemical activity has advanced, but little work directly addresses the functionality and interplay of these conserved factors. We utilised the synthetic lethality of fission yeast kinesin-8 (Klp5-Klp6) and XMAP215/chTOG (Dis1) to study their individual and overlapping roles. We found that the non-motor kinesin-8 tailbox is essential for mitotic function; mutation compromises plus-end-directed processivity. Klp5-Klp6 induces catastrophes to control microtubule length and, surprisingly, Dis1 collaborates with kinesin-8 to slow spindle elongation. Together, they enforce a maximum spindle length for a viable metaphase-anaphase transition and limit elongation during anaphase A to prevent lagging chromatids. Our work provides mechanistic insight into how kinesin-8 negatively regulates microtubules and how this functionally overlaps with Dis1 and highlights the importance of spindle length control in mitosis.
Topics: Anaphase; Chromosome Segregation; Kinesins; Kinetochores; Microscopy, Fluorescence; Microtubule-Associated Proteins; Microtubules; Prophase; Schizosaccharomyces; Schizosaccharomyces pombe Proteins; Spindle Apparatus
PubMed: 31427431
DOI: 10.1242/jcs.232306 -
The Biochemical Journal Aug 2019The spatial configuration of chromatin is fundamental to ensure any given cell can fulfil its functional duties, from gene expression to specialised cellular division.... (Review)
Review
The spatial configuration of chromatin is fundamental to ensure any given cell can fulfil its functional duties, from gene expression to specialised cellular division. Significant technological innovations have facilitated further insights into the structure, function and regulation of three-dimensional chromatin organisation. To date, the vast majority of investigations into chromatin organisation have been conducted in interphase and mitotic cells leaving meiotic chromatin relatively unexplored. In combination, cytological and genome-wide contact frequency analyses in mammalian germ cells have recently demonstrated that large-scale chromatin structures in meiotic prophase I are reminiscent of the sequential loop arrays found in mitotic cells, although interphase-like segmentation of transcriptionally active and inactive regions are also evident along the length of chromosomes. Here, we discuss the similarities and differences of such large-scale chromatin architecture, between interphase, mitotic and meiotic cells, as well as their functional relevance and the proposed modulatory mechanisms which underlie them.
Topics: Animals; Chromatin; Germ Cells; Humans; Interphase; Meiosis; Mitosis
PubMed: 31383821
DOI: 10.1042/BCJ20180512 -
Heliyon Jul 2019Imidacloprid (IMI) is a neonicotinoid insecticide widely used in agricultural activities all around the world. This compound is transported from croplands to surrounding...
Imidacloprid (IMI) is a neonicotinoid insecticide widely used in agricultural activities all around the world. This compound is transported from croplands to surrounding freshwater ecosystems, producing adverse effects on non-target organisms. Because of the relevance of aquatic macrophytes in the above-mentioned environments and the lack of studies of potential effects of IMI on them, this work aimed to assess the mitotic process and potential genotoxicity in the aquatic macrophyte L. Although the analysis of the Mitotic Index (MI) showed that IMI was not cytotoxic, the Cell Proliferation Kinetics (CPK) frequencies evidenced modifications in the kinetics of the mitotic process. Indeed, the anaphases ratio decreased at 10 and 100 μg/L IMI, while at 1000 μg/L an increase of prophases ratio and a decrease of metaphases ratio were observed. Regarding genotoxicity, IMI produced an increase of the abnormal metaphases frequency from 10 μg/L to 1000 μg/L as well as an increase in clastogenic anaphases-telophases frequency at 100 and 1000 μg/L. In addition, aneugenic anaphases-telophases and C-mitosis frequencies also increased at 1000 μg/L, confirming the effects on the mitotic spindle. Considering the genotoxic effects on through two different mechanisms (aneugenic and clastogenic) and the wide spread use of IMI in agriculture, these mechanisms of toxicity on macrophytes should be considered among other recognized effects of this insecticide on aquatic biota.
PubMed: 31372562
DOI: 10.1016/j.heliyon.2019.e02118 -
Molecular Cell Aug 2019Homologous recombination (HR) is essential for high-fidelity DNA repair during mitotic proliferation and meiosis. Yet, context-specific modifications must tailor the...
Homologous recombination (HR) is essential for high-fidelity DNA repair during mitotic proliferation and meiosis. Yet, context-specific modifications must tailor the recombination machinery to avoid (mitosis) or enforce (meiosis) the formation of reciprocal exchanges-crossovers-between recombining chromosomes. To obtain molecular insight into how crossover control is achieved, we affinity purified 7 DNA-processing enzymes that channel HR intermediates into crossovers or noncrossovers from vegetative cells or cells undergoing meiosis. Using mass spectrometry, we provide a global characterization of their composition and reveal mitosis- and meiosis-specific modules in the interaction networks. Functional analyses of meiosis-specific interactors of MutLγ-Exo1 identified Rtk1, Caf120, and Chd1 as regulators of crossing-over. Chd1, which transiently associates with Exo1 at the prophase-to-metaphase I transition, enables the formation of MutLγ-dependent crossovers through its conserved ability to bind and displace nucleosomes. Thus, rewiring of the HR network, coupled to chromatin remodeling, promotes context-specific control of the recombination outcome.
Topics: Crossing Over, Genetic; Mass Spectrometry; Meiosis; Mitosis; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins
PubMed: 31351878
DOI: 10.1016/j.molcel.2019.06.022 -
Cancer Biology & Therapy 2019Paclitaxel is a widely used anti-cancer treatment that disrupts cell cycle progression by blocking cells in mitosis. The block at mitosis, with spindles assembled from...
Paclitaxel is a widely used anti-cancer treatment that disrupts cell cycle progression by blocking cells in mitosis. The block at mitosis, with spindles assembled from short microtubules, is surprising given paclitaxel's microtubule stabilizing activity and the need to depolymerize long interphase microtubules prior to spindle formation. Cells must antagonize paclitaxel's microtubule stabilizing activity during a brief window of time at the transition from interphase to mitosis, allowing microtubule reorganization into a mitotic spindle, although the mechanism underlying microtubule depolymerization in the presence of paclitaxel has not been examined. Here we test the hypothesis that microtubule severing and/or depolymerizing proteins active at mitotic entry are necessary to clear the interphase array in paclitaxel-treated cells and allow subsequent formation of mitotic spindles formed of short microtubules. A549 and LLC-PK1 cells treated with 30nM paclitaxel approximately 4 h prior to mitotic entry successfully progress through the G2/M transition by clearing the interphase microtubule array from the cell interior outward to the cell periphery, a spatial pattern of reorganization that differs from that of cells possessing dynamic microtubules. Depletion of kinesin-8s, KIF18A and/or KIF18B obstructed interphase microtubule clearing at mitotic entry in paclitaxel-treated cells, with KIF18B making the larger contribution. Of the severing proteins, depletion of spastin, but not katanin, reduced microtubule loss as cells entered mitosis in the presence of paclitaxel. These results support a model in which KIF18A, KIF18B, and spastin promote interphase microtubule array disassembly at mitotic entry and can overcome paclitaxel-induced microtubule stability specifically at the G2/M transition.
Topics: Cell Cycle; Cell Line; Humans; Kinesins; Microtubule-Associated Proteins; Microtubules; Mitosis; Paclitaxel; Protein Multimerization; Protein Stability; Spastin
PubMed: 31345098
DOI: 10.1080/15384047.2019.1638678 -
Proceedings. Biological Sciences Jul 2019Hybrid male sterility (HMS) contributes to speciation by restricting gene flow between related taxa. Detailed cytological characterization of reproductive organs in...
Hybrid male sterility (HMS) contributes to speciation by restricting gene flow between related taxa. Detailed cytological characterization of reproductive organs in hybrid males is important for identifying phenotypes that can help guide searches of speciation genes. To investigate possible cellular causes of HMS, we performed crosses between closely related species of the Anopheles gambiae complex: An. merus with An. gambiae or An. coluzzii. We demonstrate that HMS in African malaria mosquitoes involves two defects in the reciprocal crosses: a premeiotic arrest of germline stem cells in degenerate testes and a failure of the reductional meiotic division of primary spermatocytes in normal-like testes. The premeiotic arrest in degenerate testes of hybrids is accompanied by a strong suppression of meiotic and postmeiotic genes. Unlike pure species, sex chromosomes in normal-like testes of F1 hybrids are largely unpaired during meiotic prophase I and all chromosomes show various degrees of insufficient condensation. Instead of entering reductional division in meiosis I, primary spermatocytes prematurely undergo an equational mitotic division producing non-motile diploid sperm. Thus, our study identified cytogenetic errors in interspecies hybrids that arise during the early stages of postzygotic isolation.
Topics: Adult Germline Stem Cells; Animals; Anopheles; Hybridization, Genetic; Infertility, Male; Male; Meiosis; Sex Chromosomes; Spermatocytes; Spermatogenesis; Testis
PubMed: 31288705
DOI: 10.1098/rspb.2019.1080 -
Cell Research Aug 2019Oriented cell divisions are controlled by a conserved molecular cascade involving Gαi, LGN, and NuMA. Here, we show that NDP52 regulates spindle orientation via...
Oriented cell divisions are controlled by a conserved molecular cascade involving Gαi, LGN, and NuMA. Here, we show that NDP52 regulates spindle orientation via remodeling the polar cortical actin cytoskeleton. siRNA-mediated NDP52 suppression surprisingly revealed a ring-like compact subcortical F-actin architecture surrounding the spindle in prophase/prometaphase cells, which resulted in severe defects of astral microtubule growth and an aberrant spindle orientation. Remarkably, NDP52 recruited the actin assembly factor N-WASP and regulated the dynamics of the subcortical F-actin ring in mitotic cells. Mechanistically, NDP52 was found to bind to phosphatidic acid-containing vesicles, which absorbed cytoplasmic N-WASP to regulate local filamentous actin growth at the polar cortex. Our TIRFM analyses revealed that NDP52-containing vesicles anchored N-WASP and shortened the length of actin filaments in vitro. Based on these results we propose that NDP52-containing vesicles regulate cortical actin dynamics through N-WASP to accomplish a spatiotemporal regulation between astral microtubules and the actin network for proper spindle orientation and precise chromosome segregation. In this way, intracellular vesicles cooperate with microtubules and actin filaments to regulate proper mitotic progression. Since NDP52 is absent from yeast, we reason that metazoans have evolved an elaborate spindle positioning machinery to ensure accurate chromosome segregation in mitosis.
Topics: Actin Cytoskeleton; Actins; Chromosome Segregation; Cytoplasmic Vesicles; HEK293 Cells; HeLa Cells; Humans; Microtubules; Mitosis; Nuclear Proteins; RNA Interference; Spindle Apparatus; Wiskott-Aldrich Syndrome Protein, Neuronal
PubMed: 31201383
DOI: 10.1038/s41422-019-0189-9 -
Cell Cycle (Georgetown, Tex.) Jun 2019Heterochromatin Protein 1 α (HP1α) associates with members of the chromosome passenger complex (CPC) during mitosis, at centromeres where it is required for full...
Heterochromatin Protein 1 α (HP1α) associates with members of the chromosome passenger complex (CPC) during mitosis, at centromeres where it is required for full Aurora Kinase B (AURKB) activity. Conversely, recent reports have identified AURKB as the major kinase responsible for phosphorylation of HP1α at Serine 92 (S92) during mitosis. Thus, the current study was designed to better understand the functional role of this posttranslationally modified form of HP1α. We find that S92-phosphorylated HP1α is generated in cells at early prophase, localizes to centromeres, and associates with regulators of chromosome stability, such as Inner Centromere Protein, INCENP. In mouse embryonic fibroblasts, HP1α knockout alone or reconstituted with a non-phosphorylatable (S92A) HP1α mutant results in mitotic chromosomal instability characterized by the formation of anaphase/telophase chromatin bridges and micronuclei. These effects are rescued by exogenous expression of wild type HP1α or a phosphomimetic (S92D) variant. Thus, the results from the current study extend our knowledge of the role of HP1α in chromosomal stability during mitosis.
Topics: Animals; Aurora Kinase B; Chromobox Protein Homolog 5; Chromosomal Instability; Chromosomal Proteins, Non-Histone; Chromosome Aberrations; HeLa Cells; Heterochromatin; Humans; Kinetochores; Mice; Mice, Inbred C57BL; Mitosis; Phosphorylation; Phosphoserine; Protein Binding; Protein Kinase Inhibitors
PubMed: 31130069
DOI: 10.1080/15384101.2019.1618126