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1.
Nucleus ; 13(1): 144-154, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-35298348

RESUMO

Dictyostelium amoebae perform a semi-closed mitosis, in which the nuclear envelope is fenestrated at the insertion sites of the mitotic centrosomes and around the central spindle during karyokinesis. During late telophase the centrosome relocates to the cytoplasmic side of the nucleus, the central spindle disassembles and the nuclear fenestrae become closed. Our data indicate that Dictyostelium spastin (DdSpastin) is a microtubule-binding and severing type I membrane protein that plays a role in this process. Its mitotic localization is in agreement with a requirement for the removal of microtubules that would hinder closure of the fenestrae. Furthermore, DdSpastin interacts with the HeH/ LEM-family protein Src1 in BioID analyses as well as the inner nuclear membrane protein Sun1, and shows subcellular co-localizations with Src1, Sun1, the ESCRT component CHMP7 and the IST1-like protein filactin, suggesting that the principal pathway of mitotic nuclear envelope remodeling is conserved between animals and Dictyostelium amoebae.


Assuntos
Dictyostelium , Membrana Nuclear , Animais , Divisão do Núcleo Celular , Dictyostelium/metabolismo , Mitose , Membrana Nuclear/metabolismo , Espastina/metabolismo
2.
Nat Commun ; 13(1): 772, 2022 02 09.
Artigo em Inglês | MEDLINE | ID: mdl-35140224

RESUMO

Embryogenesis depends on a tightly regulated balance between mitosis, differentiation, and morphogenesis. Understanding how the embryo uses a relatively small number of proteins to transition between growth and morphogenesis is a central question of developmental biology, but the mechanisms controlling mitosis and differentiation are considered to be fundamentally distinct. Here we show the mitotic kinase Polo, which regulates all steps of mitosis in Drosophila, also directs cellular morphogenesis after cell cycle exit. In mitotic cells, the Aurora kinases activate Polo to control a cytoskeletal regulatory module that directs cytokinesis. We show that in the post-mitotic mesoderm, the control of Polo activity transitions from the Aurora kinases to the uncharacterized kinase Back Seat Driver (Bsd), where Bsd and Polo cooperate to regulate muscle morphogenesis. Polo and its effectors therefore direct mitosis and cellular morphogenesis, but the transition from growth to morphogenesis is determined by the spatiotemporal expression of upstream activating kinases.


Assuntos
Drosophila/metabolismo , Mitose , Morfogênese/fisiologia , Fosfotransferases/metabolismo , Animais , Aurora Quinases/metabolismo , Ciclo Celular , Proteínas de Ciclo Celular/metabolismo , Divisão do Núcleo Celular , Citocinese , Drosophila/genética , Proteínas de Drosophila , Regulação da Expressão Gênica no Desenvolvimento , Proteínas Associadas aos Microtúbulos , Morfogênese/genética , Fosfotransferases/genética , Fuso Acromático/metabolismo
3.
Development ; 149(2)2022 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-35001104

RESUMO

Biological systems are highly complex, yet notably ordered structures can emerge. During syncytial stage development of the Drosophila melanogaster embryo, nuclei synchronously divide for nine cycles within a single cell, after which most of the nuclei reach the cell cortex. The arrival of nuclei at the cortex occurs with remarkable positional order, which is important for subsequent cellularisation and morphological transformations. Yet, the mechanical principles underlying this lattice-like positional order of nuclei remain untested. Here, using quantification of nuclei position and division orientation together with embryo explants, we show that short-ranged repulsive interactions between microtubule asters ensure the regular distribution and maintenance of nuclear positions in the embryo. Such ordered nuclear positioning still occurs with the loss of actin caps and even the loss of the nuclei themselves; the asters can self-organise with similar distribution to nuclei in the wild-type embryo. The explant assay enabled us to deduce the nature of the mechanical interaction between pairs of nuclei. We used this to predict how the nuclear division axis orientation changes upon nucleus removal from the embryo cortex, which we confirmed in vivo with laser ablation. Overall, we show that short-ranged microtubule-mediated repulsive interactions between asters are important for ordering in the early Drosophila embryo and minimising positional irregularity.


Assuntos
Blastoderma/metabolismo , Divisão do Núcleo Celular , Células Gigantes/metabolismo , Animais , Blastoderma/citologia , Núcleo Celular/metabolismo , Drosophila melanogaster , Células Gigantes/citologia , Microtúbulos/metabolismo , Estresse Mecânico
4.
Nan Fang Yi Ke Da Xue Xue Bao ; 41(10): 1509-1518, 2021 Oct 20.
Artigo em Chinês | MEDLINE | ID: mdl-34755666

RESUMO

OBJECTIVE: To identify the key genes involved in the transformation of hepatitis B virus (HBV) into hepatocellular carcinoma (HCC) and explore the underlying molecular mechanisms. METHODS: We analyzed the mRNA microarray data of 119 HBV-related HCC tissues and 252 HBV-related non-tumor tissues in GSE55092, GSE84044 and GSE121248 from the GEO database, and the "sva" R package was used to remove the batch effects. Integration analysis was performed to identify the differentially expressed genes (DEGs) in HBV-related liver cancer and liver tissues with HBV infection. The significant DEGs were functionally annotated using GO and KEGG analyses, and the most important modules and hub genes were explored with STRING analysis. Kaplan-Meier and Oncomine databases were used to verify the HCC gene expression data in the TCGA database to explore the correlations of the hub genes with the occurrence, progression and prognosis of HCC. We also examined the expressions of the hub genes in 17 pairs of surgical specimens of HCC and adjacent tissues using RT-qPCR. RESULTS: We identified a total of 121 DEGs and 3 genetic markers in HCC (P < 0.01). These DEGs included cyclin1 (CDK1), cyclin B1 (CCNB1), and nuclear division cycle 80 (NDC80), which participated in cell cycle, pyrimidine metabolism and DNA replication and were highly correlated (P < 0.05). Analysis of the UALCAN database confirmed high expressions of these 3 genes in HCC tissues, which were correlated with a low survival rate of the patients, as shown by Kaplan-Meier analysis of the prognostic data from the UALCAN database. CDK1, CCNB1 and NDC80 were all correlated with the clinical grading of HCC (P < 0.05). The results of RT-qPCR on the surgical specimens verified significantly higher expressions of CDK1, CCNB1 and NDC80 mRNA in HCC tissues than in the adjacent tissues. CONCLUSION: CDK1, CCNB1 and NDC80 genes can be used as prognostic markers of HBV-related HCC and may serve as potential targets in preclinical studies and clinical treatment of HCC.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Proteína Quinase CDC2/genética , Carcinoma Hepatocelular/genética , Divisão do Núcleo Celular , Biologia Computacional , Ciclina B1/genética , Proteínas do Citoesqueleto , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Vírus da Hepatite B/genética , Humanos , Neoplasias Hepáticas/genética , Prognóstico
5.
Dev Cell ; 56(15): 2192-2206.e8, 2021 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-34331869

RESUMO

To generate haploid gametes, germ cells undergo two consecutive meiotic divisions requiring key changes to the cell division machinery. Here, we demonstrate that the protease separase rewires key cell division processes at the meiosis I/II transition by cleaving the meiosis-specific protein Meikin. Separase proteolysis does not inactivate Meikin but instead alters its function to create a distinct activity state. Full-length Meikin and the C-terminal Meikin separase cleavage product both localize to kinetochores, bind to Plk1 kinase, and promote Rec8 cleavage, but our results reveal distinct roles for these proteins in controlling meiosis. Mutations that prevent Meikin cleavage or that conditionally inactivate Meikin at anaphase I result in defective meiosis II chromosome alignment in mouse oocytes. Finally, as oocytes exit meiosis, C-Meikin is eliminated by APC/C-mediated degradation prior to the first mitotic division. Thus, multiple regulatory events irreversibly modulate Meikin activity during successive meiotic divisions to rewire the cell division machinery at two distinct transitions.


Assuntos
Proteínas Cromossômicas não Histona/metabolismo , Meiose/fisiologia , Separase/metabolismo , Animais , Animais não Endogâmicos , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/fisiologia , Divisão Celular/fisiologia , Divisão do Núcleo Celular , Centrômero/metabolismo , Proteínas Cromossômicas não Histona/fisiologia , Segregação de Cromossomos , Feminino , Células HeLa , Humanos , Cinetocoros/metabolismo , Camundongos , Oócitos/metabolismo , /fisiologia , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas/fisiologia , Separase/fisiologia
6.
Curr Biol ; 31(18): 4104-4110.e5, 2021 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-34293333

RESUMO

The evolutionary path from protists to multicellular animals remains a mystery. Recent work on the genomes of several unicellular relatives of animals has shaped our understanding of the genetic changes that may have occurred in this transition.1-3 However, the specific cellular modifications that took place to accommodate these changes remain unclear. To address this, we need to compare metazoan cells with those of their extant relatives, which are choanoflagellates, filastereans, ichthyosporeans, and corallochytreans/pluriformeans. Interestingly, these lineages display a range of developmental patterns potentially homologous to animal ones. Genetic tools have already been established in three of those lineages.4-7 However, there are no genetic tools available for Corallochytrea. We here report the development of stable transfection in the corallochytrean Corallochytrium limacisporum. Using these tools, we discern previously unknown biological features of C. limacisporum. In particular, we identify two different paths for cell division-binary fission and coenocytic growth-that reveal a non-linear life cycle. Additionally, we found that C. limacisporum is binucleate for most of its life cycle, and that, contrary to what happens in most eukaryotes, nuclear division is decoupled from cellular division. Moreover, its actin cytoskeleton shares characteristics with both fungal and animal cells. The establishment of these tools in C. limacisporum fills an important gap in the unicellular relatives of animals, opening up new avenues of research to elucidate the specific cellular changes that occurred in the evolution of animals.


Assuntos
Eucariotos , Fungos , Animais , Divisão do Núcleo Celular , Eucariotos/genética , Fungos/genética , Filogenia , Transfecção
7.
Curr Biol ; 31(18): 3973-3983.e4, 2021 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-34297912

RESUMO

Although nuclei are the defining features of eukaryotes, we still do not fully understand how the nuclear compartment is duplicated and partitioned during division. This is especially the case for organisms that do not completely disassemble their nuclear envelope upon entry into mitosis. In studying this process in Drosophila neural stem cells, which undergo asymmetric divisions, we find that the nuclear compartment boundary persists during mitosis thanks to the maintenance of a supporting nuclear lamina. This mitotic nuclear envelope is then asymmetrically remodeled and partitioned to give rise to two daughter nuclei that differ in envelope composition and exhibit a >30-fold difference in volume. The striking difference in nuclear size was found to depend on two consecutive processes: asymmetric nuclear envelope resealing at mitotic exit at sites defined by the central spindle, and differential nuclear growth that appears to depend on the available local reservoir of ER/nuclear membranes, which is asymmetrically partitioned between the two daughter cells. Importantly, these asymmetries in size and composition of the daughter nuclei, and the associated asymmetries in chromatin organization, all become apparent long before the cortical release and the nuclear import of cell fates determinants. Thus, asymmetric nuclear remodeling during stem cell divisions may contribute to the generation of cellular diversity by initiating distinct transcriptional programs in sibling nuclei that contribute to later changes in daughter cell identity and fate.


Assuntos
Células-Tronco Neurais , Irmãos , Núcleo Celular , Divisão do Núcleo Celular , Cromatina , Humanos , Mitose , Membrana Nuclear
8.
Epigenetics Chromatin ; 14(1): 34, 2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34301312

RESUMO

Histone chaperones facilitate DNA replication and repair by promoting chromatin assembly, disassembly and histone exchange. Following histones synthesis and nucleosome assembly, the histones undergo posttranslational modification by different enzymes and are deposited onto chromatins by various histone chaperones. In Tetrahymena thermophila, histones from macronucleus (MAC) and micronucleus (MIC) have been comprehensively investigated, but the function of histone chaperones remains unclear. Histone chaperone Nrp1 in Tetrahymena contains four conserved tetratricopepeptide repeat (TPR) domains and one C-terminal nuclear localization signal. TPR2 is typically interrupted by a large acidic motif. Immunofluorescence staining showed that Nrp1 is located in the MAC and MICs, but disappeared in the apoptotic parental MAC and the degraded MICs during the conjugation stage. Nrp1 was also colocalized with α-tubulin around the spindle structure. NRP1 knockdown inhibited cellular proliferation and led to the loss of chromosome, abnormal macronuclear amitosis, and disorganized micronuclear mitosis during the vegetative growth stage. During sexual developmental stage, the gametic nuclei failed to be selected and abnormally degraded in NRP1 knockdown mutants. Affinity purification combined with mass spectrometry analysis indicated that Nrp1 is co-purified with core histones, heat shock proteins, histone chaperones, and DNA damage repair proteins. The physical direct interaction of Nrp1 and Asf1 was also confirmed by pull-down analysis in vitro. The results show that histone chaperone Nrp1 is involved in micronuclear mitosis and macronuclear amitosis in the vegetative growth stage and maintains gametic nuclei formation during the sexual developmental stage. Nrp1 is required for chromatin stability and nuclear division in Tetrahymena thermophila.


Assuntos
Tetrahymena thermophila , Divisão do Núcleo Celular , Cromatina , Cromossomos , Chaperonas de Histonas/genética , Tetrahymena thermophila/genética
9.
Mol Biol Cell ; 32(20): br3, 2021 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-34319762

RESUMO

Force generation by the molecular motor myosin II (MII) at the actin cortex is a universal feature of animal cells. Despite its central role in driving cell shape changes, the mechanisms underlying MII regulation at the actin cortex remain incompletely understood. Here we show that myosin light chain kinase (MLCK) promotes MII turnover at the mitotic cortex. Inhibition of MLCK resulted in an alteration of the relative levels of phosphorylated regulatory light chain (RLC), with MLCK preferentially creating a short-lived pRLC species and Rho-associated kinase (ROCK) preferentially creating a stable ppRLC species during metaphase. Slower turnover of MII and altered RLC homeostasis on MLCK inhibition correlated with increased cortex tension, driving increased membrane bleb initiation and growth, but reduced bleb retraction during mitosis. Taken together, we show that ROCK and MLCK play distinct roles at the actin cortex during mitosis; ROCK activity is required for recruitment of MII to the cortex, while MLCK activity promotes MII turnover. Our findings support the growing evidence that MII turnover is an essential dynamic process influencing the mechanical output of the actin cortex.


Assuntos
Actinas/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Miosina Tipo II/metabolismo , Quinase de Cadeia Leve de Miosina/metabolismo , Vesícula/metabolismo , Proteínas de Ligação ao Cálcio/fisiologia , Divisão do Núcleo Celular , Proteínas do Citoesqueleto/metabolismo , Células HeLa , Humanos , Mitose/fisiologia , Cadeias Leves de Miosina/metabolismo , Miosina Tipo II/fisiologia , Quinase de Cadeia Leve de Miosina/fisiologia , Fosforilação , Quinases Associadas a rho/metabolismo
10.
PLoS Genet ; 17(4): e1009327, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33901174

RESUMO

The Aurora protein kinases are well-established regulators of spindle building and chromosome segregation in mitotic and meiotic cells. In mouse oocytes, there is significant Aurora kinase A (AURKA) compensatory abilities when the other Aurora kinase homologs are deleted. Whether the other homologs, AURKB or AURKC can compensate for loss of AURKA is not known. Using a conditional mouse oocyte knockout model, we demonstrate that this compensation is not reciprocal because female oocyte-specific knockout mice are sterile, and their oocytes fail to complete meiosis I. In determining AURKA-specific functions, we demonstrate that its first meiotic requirement is to activate Polo-like kinase 1 at acentriolar microtubule organizing centers (aMTOCs; meiotic spindle poles). This activation induces fragmentation of the aMTOCs, a step essential for building a bipolar spindle. We also show that AURKA is required for regulating localization of TACC3, another protein required for spindle building. We conclude that AURKA has multiple functions essential to completing MI that are distinct from AURKB and AURKC.


Assuntos
Aurora Quinase A/genética , Proteínas de Ciclo Celular/genética , Proteínas Fetais/genética , Meiose/genética , Proteínas Associadas aos Microtúbulos/genética , Oócitos/crescimento & desenvolvimento , Proteínas Proto-Oncogênicas/genética , Animais , Aurora Quinase B/genética , Aurora Quinase C/genética , Divisão do Núcleo Celular/genética , Segregação de Cromossomos/genética , Feminino , Regulação da Expressão Gênica no Desenvolvimento/genética , Humanos , Camundongos , Centro Organizador dos Microtúbulos/metabolismo , Oócitos/metabolismo , Fuso Acromático/genética , Polos do Fuso/genética
11.
Cancer Commun (Lond) ; 41(6): 492-510, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33734616

RESUMO

BACKGROUND: Considering the increase in the proportion of lung adenocarcinoma (LUAD) cases among all lung cancers and its considerable contribution to cancer-related deaths worldwide, we sought to identify novel oncogenes to provide potential targets and facilitate a better understanding of the malignant progression of LUAD. METHODS: The results from the screening of transcriptome and survival analyses according to the integrated Gene Expression Omnibus (GEO) datasets and The Cancer Genome Atlas (TCGA) data were combined, and a promising risk biomarker called meiotic nuclear divisions 1 (MND1) was selectively acquired. Cell viability assays and subcutaneous xenograft models were used to validate the oncogenic role of MND1 in LUAD cell proliferation and tumor growth. A series of assays, including mass spectrometry, co-immunoprecipitation (Co-IP), and chromatin immunoprecipitation (ChIP), were performed to explore the underlying mechanism. RESULTS: MND1 up-regulation was identified to be an independent risk factor for overall survival in LUAD patients evaluated by both tissue microarray staining and third party data analysis. In vivo and in vitro assays showed that MND1 promoted LUAD cell proliferation by regulating cell cycle. The results of the Co-IP, ChIP and dual-luciferase reporter assays validated that MND1 competitively bound to tumor suppressor Kruppel-like factor 6 (KLF6), and thereby protecting E2F transcription factor 1 (E2F1) from KLF6-induced transcriptional repression. Luciferase reporter and ChIP assays found that E2F1 activated MND1 transcription by binding to its promoter in a feedback manner. CONCLUSIONS: MND1, KLF6, and E2F1 form a positive feedback loop to regulate cell cycle and confer DDP resistance in LUAD. MND1 is crucial for malignant progression and may be a potential therapeutic target in LUAD patients.


Assuntos
Adenocarcinoma de Pulmão , Neoplasias Pulmonares , Adenocarcinoma de Pulmão/genética , Ciclo Celular/genética , Proteínas de Ciclo Celular , Divisão do Núcleo Celular , Fator de Transcrição E2F1/genética , Retroalimentação , Humanos , Fator 6 Semelhante a Kruppel , Neoplasias Pulmonares/genética
12.
Cell Cycle ; 20(2): 211-224, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33404279

RESUMO

Combining targeted therapeutic agents is an attractive cancer treatment strategy associated with high efficacy and low toxicity. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is an essential factor in DNA damage repair. Studies from us and others have revealed that DNA-PKcs also plays an important role in normal mitosis progression. Histone deacetylase (HDACs) inhibitors commonly lead to mitotic aberration and have been approved for treating various cancers in the clinic. We showed that DNA-PKcs depletion or kinase activity inhibition increases cancer cells' sensitivity to HDACs inhibitors in vitro and in vivo. DNA-PKcs deficiency significantly enhances HDACs inhibitors (HDACi)-induced mitotic arrest and is followed by apoptotic cell death. Mechanistically, we found that DNA-PKcs binds to HDAC6 and facilitates its acetylase activity. HDACi is more likely to impair HDAC6-induced deacetylation of HSP90 and abrogate HSP90's chaperone function on Aurora A, a critical mitotic kinase that regulates centrosome separation and mitotic spindle assembly in DNA-PKcs-deficient cells. Our current work indicates crosstalk between DNA-PKcs and HDACs signaling pathways, and highlights that the combined targeting of DNA-PKcs and HDACs can be used in cancer therapy. Abbreviations: DNA-PKcs, DNA-dependent protein kinase catalytic subunit, HDACs, Histone deacetylases, DSBs, DNA double-strand breaks, ATM, ataxia telangiectasia mutated, ATR, ATM-Rad3-related.


Assuntos
Proteína Quinase Ativada por DNA/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Desacetilase 6 de Histona/metabolismo , Chaperonas Moleculares/metabolismo , Proteínas Mutadas de Ataxia Telangiectasia/metabolismo , Proteínas de Ciclo Celular/metabolismo , Divisão do Núcleo Celular/genética , Divisão do Núcleo Celular/fisiologia , Dano ao DNA/genética , Reparo do DNA/genética , Desacetilase 6 de Histona/genética , Humanos , Proteínas Supressoras de Tumor/metabolismo
13.
Protoplasma ; 258(3): 621-632, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33389128

RESUMO

Magnolia, a basal angiosperm genus important for evolutionary and phylogenetic studies, is known to have male meiotic features not seen in the vast majority of angiosperms. However, knowledge about male meiosis in Magnolia is still fragmentary. Here, we report findings from an extensive investigation into male meiosis in Magnolia denudata using a combination of light and electron microscopy methods. Male meiosis in M. denudata was synchronous in prophase I but asynchronous in subsequent nuclear divisions. The polarized microspore mother cells from late prophase I onward had an elongated cell shape and thickened callose wall areas at the two smaller ends of the cell. The first nuclear division occurred along the long axis of the cell and the first callose furrow formed at the equatorial plane of the first nuclear division at the late telophase I stage. The second equatorial callose furrow formed after telophase II in a plane perpendicular to the first callose furrow. While cytokinesis occurred centripetally from the two furrows, a central callose wall island (CWI) appeared in the center of the cell and dense assemblies of vesicles and short tubules decorated the cytoplasmic regions between the furrows and the CWI. This cytokinesis mode differs from either the centripetal or the centrifugal mode of cytokinesis in microsporogenesis in the vast majority of angiosperms. As a result of this unusual cytokinesis, a large central callose mass remains in the mature tetrads. These observations may be useful to studies of cytokinetic mechanisms, evolution of microsporogenesis, and phylogenetics of angiosperms.


Assuntos
Divisão do Núcleo Celular/fisiologia , Polaridade Celular/fisiologia , Citocinese/fisiologia , Magnolia/química , Meiose/fisiologia
14.
Cell Microbiol ; 23(3): e13284, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33124706

RESUMO

The eukaryotic cell cycle is typically divided into distinct phases with cytokinesis immediately following mitosis. To ensure proper cell division, each phase is tightly coordinated via feedback controls named checkpoints. During its asexual replication cycle, the malaria parasite Plasmodium falciparum undergoes multiple asynchronous rounds of mitosis with segregation of uncondensed chromosomes followed by nuclear division with intact nuclear envelope. The multi-nucleated schizont is then subjected to a single round of cytokinesis that produces dozens of daughter cells called merozoites. To date, no cell cycle checkpoints have been identified that regulate the Plasmodium spp. mode of division. Here, we identify the Plasmodium homologue of the Mini-Chromosome Maintenance Complex Binding Protein (PfMCMBP), which co-purified with the Mini-Chromosome Maintenance (MCM) complex, a replicative helicase required for genomic DNA replication. By conditionally depleting PfMCMBP, we disrupt nuclear morphology and parasite proliferation without causing a block in DNA replication. By immunofluorescence microscopy, we show that PfMCMBP depletion promotes the formation of mitotic spindle microtubules with extensions to more than one DNA focus and abnormal centrin distribution. Strikingly, PfMCMBP-deficient parasites complete cytokinesis and form aneuploid merozoites with variable cellular and nuclear sizes. Our study demonstrates that the parasite lacks a robust checkpoint response to prevent cytokinesis following aberrant karyokinesis.


Assuntos
Divisão do Núcleo Celular , Citocinese , Proteínas de Manutenção de Minicromossomo/metabolismo , Plasmodium falciparum/citologia , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Cromossomos/metabolismo , Cromossomos/ultraestrutura , Técnicas de Silenciamento de Genes , Merozoítos/citologia , Merozoítos/crescimento & desenvolvimento , Centro Organizador dos Microtúbulos/metabolismo , Centro Organizador dos Microtúbulos/ultraestrutura , Proteínas Nucleares/genética , Plasmodium falciparum/genética , Plasmodium falciparum/crescimento & desenvolvimento , Proteínas de Protozoários/genética , Esquizontes/fisiologia
15.
Medicine (Baltimore) ; 99(49): e22655, 2020 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-33285674

RESUMO

To explore the gene modules and key genes of head and neck squamous cell carcinoma (HNSCC), a bioinformatics algorithm based on the gene co-expression network analysis was proposed in this study.Firstly, differentially expressed genes (DEGs) were identified and a gene co-expression network (i-GCN) was constructed with Pearson correlation analysis. Then, the gene modules were identified with 5 different community detection algorithms, and the correlation analysis between gene modules and clinical indicators was performed. Gene Ontology (GO) analysis was used to annotate the biological pathways of the gene modules. Then, the key genes were identified with 2 methods, gene significance (GS) and PageRank algorithm. Moreover, we used the Disgenet database to search the related diseases of the key genes. Lastly, the online software onclnc was used to perform the survival analysis on the key genes and draw survival curves.There were 2600 up-regulated and 1547 down-regulated genes identified in HNSCC. An i-GCN was constructed with Pearson correlation analysis. Then, the i-GCN was divided into 9 gene modules. The result of association analysis showed that, sex was mainly related to mitosis and meiosis processes, event was mainly related to responding to interferons, viruses and T cell differentiation processes, T stage was mainly related to muscle development and contraction, regulation of protein transport activity processes, N stage was mainly related to mitosis and meiosis processes, while M stage was mainly related to responding to interferons and immune response processes. Lastly, 34 key genes were identified, such as CDKN2A, HOXA1, CDC7, PPL, EVPL, PXN, PDGFRB, CALD1, and NUSAP1. Among them, HOXA1, PXN, and NUSAP1 were negatively correlated with the survival prognosis.HOXA1, PXN, and NUSAP1 might play important roles in the progression of HNSCC and severed as potential biomarkers for future diagnosis.


Assuntos
Redes Reguladoras de Genes/fisiologia , Neoplasias de Cabeça e Pescoço/genética , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Divisão do Núcleo Celular/fisiologia , Biologia Computacional/métodos , Regulação para Baixo , Ontologia Genética , Neoplasias de Cabeça e Pescoço/imunologia , Humanos , Fatores Sexuais , Carcinoma de Células Escamosas de Cabeça e Pescoço/imunologia , Linfócitos T/metabolismo , Regulação para Cima
16.
PLoS Biol ; 18(11): e3000917, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33180788

RESUMO

The transition from mitosis into the first gap phase of the cell cycle in budding yeast is controlled by the Mitotic Exit Network (MEN). The network interprets spatiotemporal cues about the progression of mitosis and ensures that release of Cdc14 phosphatase occurs only after completion of key mitotic events. The MEN has been studied intensively; however, a unified understanding of how localisation and protein activity function together as a system is lacking. In this paper, we present a compartmental, logical model of the MEN that is capable of representing spatial aspects of regulation in parallel to control of enzymatic activity. We show that our model is capable of correctly predicting the phenotype of the majority of mutants we tested, including mutants that cause proteins to mislocalise. We use a continuous time implementation of the model to demonstrate that Cdc14 Early Anaphase Release (FEAR) ensures robust timing of anaphase, and we verify our findings in living cells. Furthermore, we show that our model can represent measured cell-cell variation in Spindle Position Checkpoint (SPoC) mutants. This work suggests a general approach to incorporate spatial effects into logical models. We anticipate that the model itself will be an important resource to experimental researchers, providing a rigorous platform to test hypotheses about regulation of mitotic exit.


Assuntos
Ciclo Celular/genética , Pontos de Checagem da Fase M do Ciclo Celular/fisiologia , Ciclo Celular/fisiologia , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/fisiologia , Divisão do Núcleo Celular/fisiologia , Pontos de Checagem da Fase M do Ciclo Celular/genética , Mitose/fisiologia , Fosforilação , Proteínas Tirosina Fosfatases/genética , Proteínas Tirosina Fosfatases/metabolismo , Proteínas Tirosina Fosfatases/fisiologia , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/fisiologia , Saccharomycetales/genética , Saccharomycetales/metabolismo , Fuso Acromático/fisiologia
17.
PLoS Genet ; 16(10): e1008928, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-33001976

RESUMO

Regular chromosome segregation during the first meiotic division requires prior pairing of homologous chromosomes into bivalents. During canonical meiosis, linkage between homologous chromosomes is maintained until late metaphase I by chiasmata resulting from meiotic recombination in combination with distal sister chromatid cohesion. Separase-mediated elimination of cohesin from chromosome arms at the end of metaphase I permits terminalization of chiasmata and homolog segregation to opposite spindle poles during anaphase I. Interestingly, separase is also required for bivalent splitting during meiosis I in Drosophila males, where homologs are conjoined by an alternative mechanism independent of meiotic recombination and cohesin. Here we report the identification of a novel alternative homolog conjunction protein encoded by the previously uncharacterized gene univalents only (uno). The univalents that are present in uno null mutants at the start of meiosis I, instead of normal bivalents, are segregated randomly. In wild type, UNO protein is detected in dots associated with bivalent chromosomes and most abundantly at the localized pairing site of the sex chromosomes. UNO is cleaved by separase. Expression of a mutant UNO version with a non-functional separase cleavage site restores homolog conjunction in a uno null background. However, separation of bivalents during meiosis I is completely abrogated by this non-cleavable UNO version. Therefore, we propose that homolog separation during Drosophila male meiosis I is triggered by separase-mediated cleavage of UNO.


Assuntos
Proteínas de Drosophila/genética , Meiose/genética , Separase/genética , Fatores de Transcrição/genética , Animais , Proteínas de Ciclo Celular/genética , Divisão do Núcleo Celular/genética , Centrômero/genética , Cromátides/genética , Proteínas Cromossômicas não Histona/genética , Segregação de Cromossomos/genética , Drosophila melanogaster/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Masculino , Metáfase/genética , Cromossomos Sexuais/genética
18.
Sci Rep ; 10(1): 13887, 2020 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-32807835

RESUMO

Methylglyoxal (MG) is a natural metabolite derived from glycolysis, and it inhibits the growth of cells in all kinds of organisms. We recently reported that MG inhibits nuclear division in Saccharomyces cerevisiae. However, the mechanism by which MG blocks nuclear division remains unclear. Here, we show that increase in the levels of phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2) is crucial for the inhibitory effects of MG on nuclear division, and the deletion of PtdIns(3,5)P2-effector Atg18 alleviated the MG-mediated inhibitory effects. Previously, we reported that MG altered morphology of the vacuole to a single swelling form, where PtdIns(3,5)P2 accumulates. The changes in the vacuolar morphology were also needed by MG to exert its inhibitory effects on nuclear division. The known checkpoint machinery, including the spindle assembly checkpoint and morphological checkpoint, are not involved in the blockade of nuclear division by MG. Our results suggest that both the accumulation of Atg18 on the vacuolar membrane and alterations in vacuolar morphology are necessary for the MG-induced inhibition of nuclear division.


Assuntos
Proteínas Relacionadas à Autofagia/metabolismo , Membrana Celular/metabolismo , Divisão do Núcleo Celular/efeitos dos fármacos , Proteínas de Membrana/metabolismo , Aldeído Pirúvico/farmacologia , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Vacúolos/metabolismo , Alelos , Proteínas Relacionadas à Autofagia/genética , Membrana Celular/efeitos dos fármacos , Proteínas de Membrana/genética , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Mutação/genética , Fosfatos de Fosfatidilinositol/farmacologia , Fosforilação/efeitos dos fármacos , Saccharomyces cerevisiae/efeitos dos fármacos , Proteínas de Saccharomyces cerevisiae/genética , Polos do Fuso/efeitos dos fármacos , Polos do Fuso/metabolismo , Vacúolos/efeitos dos fármacos
19.
Mol Biol Cell ; 31(22): 2437-2451, 2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-32845810

RESUMO

NuMA is an abundant long coiled-coil protein that plays a prominent role in spindle organization during mitosis. In interphase, NuMA is localized to the nucleus and hypothesized to control gene expression and chromatin organization. However, because of the prominent mitotic phenotype upon NuMA loss, its precise function in the interphase nucleus remains elusive. Here, we report that NuMA is associated with chromatin in interphase and prophase but released upon nuclear envelope breakdown (NEBD) by the action of Cdk1. We uncover that NuMA directly interacts with DNA via evolutionarily conserved sequences in its C-terminus. Notably, the expression of the DNA-binding-deficient mutant of NuMA affects chromatin decondensation at the mitotic exit, and nuclear shape in interphase. We show that the nuclear shape defects observed upon mutant NuMA expression are due to its potential to polymerize into higher-order fibrillar structures. Overall, this work establishes the spindle-independent function of NuMA in choreographing proper chromatin decompaction and nuclear shape by directly associating with the DNA.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Cromatina/metabolismo , Mitose/fisiologia , Antígenos Nucleares/metabolismo , Proteína Quinase CDC2/metabolismo , Ciclo Celular , Proteínas de Ciclo Celular/genética , Núcleo Celular/metabolismo , Divisão do Núcleo Celular , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Cromossomos/metabolismo , DNA/metabolismo , Células HeLa , Humanos , Proteínas Associadas à Matriz Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Fuso Acromático/metabolismo
20.
Nucleic Acids Res ; 48(16): 9007-9018, 2020 09 18.
Artigo em Inglês | MEDLINE | ID: mdl-32710625

RESUMO

In most animals, the start of embryogenesis requires specific histones. In Drosophila linker histone variant BigH1 is present in early embryos. To uncover the specific role of this alternative linker histone at early embryogenesis, we established fly lines in which domains of BigH1 have been replaced partially or completely with that of H1. Analysis of the resulting Drosophila lines revealed that at normal temperature somatic H1 can substitute the alternative linker histone, but at low temperature the globular and C-terminal domains of BigH1 are essential for embryogenesis. In the presence of BigH1 nucleosome stability increases and core histone incorporation into nucleosomes is more rapid, while nucleosome spacing is unchanged. Chromatin formation in the presence of BigH1 permits the fast-paced nuclear divisions of the early embryo. We propose a model which explains how this specific linker histone ensures the rapid nucleosome reassembly required during quick replication cycles at the start of embryogenesis.


Assuntos
Divisão do Núcleo Celular , Cromatina/metabolismo , Proteínas de Drosophila/fisiologia , Drosophila/embriologia , Histonas/metabolismo , Nucleossomos/metabolismo , Animais , Montagem e Desmontagem da Cromatina , Embrião não Mamífero , Desenvolvimento Embrionário , Histonas/fisiologia
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