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1.
Nat Commun ; 10(1): 2861, 2019 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-31253795

RESUMO

Centromeres provide a pivotal function for faithful chromosome segregation. They serve as a foundation for the assembly of the kinetochore complex and spindle connection, which is essential for chromosome biorientation. Cells lacking Polo-like kinase 1 (PLK1) activity suffer severe chromosome alignment defects, which is believed primarily due to unstable kinetochore-microtubule attachment. Here, we reveal a previously undescribed mechanism named 'centromere disintegration' that drives chromosome misalignment in PLK1-inactivated cells. We find that PLK1 inhibition does not necessarily compromise metaphase establishment, but instead its maintenance. We demonstrate that this is caused by unlawful unwinding of DNA by BLM helicase at a specific centromere domain underneath kinetochores. Under bipolar spindle pulling, the distorted centromeres are promptly decompacted into DNA threadlike molecules, leading to centromere rupture and whole-chromosome arm splitting. Consequently, chromosome alignment collapses. Our study unveils an unexpected role of PLK1 as a chromosome guardian to maintain centromere integrity for chromosome biorientation.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Segregação de Cromossomos/fisiologia , Mitose/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Fuso Acromático/fisiologia , Linhagem Celular , Pareamento Cromossômico/fisiologia , Humanos , Cinetocoros , Interferência de RNA , Timidina/farmacologia
2.
Mol Biol (Mosk) ; 53(3): 446-455, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31184610

RESUMO

Ran is an evolutionarily conserved GTPase crucial in regulating various cell divisions, including mitosis and meiosis. A previous study showed that the knockdown of RAN1 inhibited macronuclear amitosis with the abnormal organization of intramacronuclear microtubules in Tetrahymena thermophila. This study aimed to further investigate the effects of the inducible expression of wild-type Ran1 (Ran1WT), GTP-bound Ran1-mimetic (Ran1Q70L), and GDP-bound Ran1-mimetic (Ran1T25N) on cytoplasmic microtubule assembly during amitosis of T. thermophila, based on previous studies about their effects on intramacronuclear microtubule. The mutant strains of T. thermophila for inducible expression of Ran1WT/T25N/Q70L by Cd^(2+) were constructed. The inducibly expressed HA-Ran1Q70L/T25N distributed asymmetrically across the macronuclear envelope during amitosis. At the lower level of inducible expression, only Ran1T25N showed a significant decreasing effect on T. thermophila reproduction, macronuclear amitosis and cytokinesis. At the higher level of inducible expression, Ran1WT/Q70L/T25N inhibited T. thermophila reproduction, macronuclear amitosis and cytokinesis, and the inhibitive effect of Ran1T25N was the most significant. The inducible expression of Ran1WT/Q70L/T25N led to defects in amitosis and cytokinesis with abnormal cytoplasmic microtubule assembly. These results further confirmed the regulatory function of Ran1 on amitosis and suggested a novel role of Ran1 in cytokinesis and the alignment of cytoplasmic microtubules in T. thermophila.


Assuntos
Citocinese , Guanosina Difosfato/metabolismo , Guanosina Trifosfato/metabolismo , Microtúbulos/metabolismo , Mutação , Proteínas de Protozoários/metabolismo , Tetrahymena thermophila , Proteína ran de Ligação ao GTP/metabolismo , Microtúbulos/patologia , Mitose , Proteínas de Protozoários/genética , Tetrahymena thermophila/citologia , Tetrahymena thermophila/genética , Tetrahymena thermophila/metabolismo , Proteína ran de Ligação ao GTP/genética
3.
Biochim Biophys Acta Rev Cancer ; 1872(1): 60-65, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31152819

RESUMO

Hepatocellular carcinoma (HCC), the most common form of liver cancer, represents a health problem in hepatic viruses-eradicating era because obesity, type 2 diabetes, and nonalcoholic steatohepatitis (NASH) are considered emerging pathogenic factors. Metabolic disorders underpin mitotic errors that lead to numerical and structural chromosome aberrations in a significant proportion of cell divisions. Here, we review that genomically unstable HCCs show evidence for a paradoxically DNA damage response (DDR) which leads to ongoing chromosome segregation errors. The understanding of DDR induced by defective mitoses is crucial to our ability to develop or improve liver cancer therapeutic strategies.


Assuntos
Carcinoma Hepatocelular/genética , Genoma Humano/genética , Instabilidade Genômica/genética , Neoplasias Hepáticas/genética , Carcinoma Hepatocelular/patologia , Instabilidade Cromossômica/genética , Segregação de Cromossomos/genética , Dano ao DNA/genética , Humanos , Neoplasias Hepáticas/patologia , Mitose/genética
4.
Nat Commun ; 10(1): 2854, 2019 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-31253781

RESUMO

SETD1A, a Set1/COMPASS family member maintaining histone-H3-lysine-4 (H3K4) methylation on transcriptionally active promoters, is overexpressed in breast cancer. Here, we show that SETD1A supports mitotic processes and consequentially, its knockdown induces senescence. SETD1A, through promoter H3K4 methylation, regulates several genes orchestrating mitosis and DNA-damage responses, and its depletion causes chromosome misalignment and segregation defects. Cell cycle arrest in SETD1A knockdown senescent cells is independent of mutations in p53, RB and p16, known senescence mediators; instead, it is sustained through transcriptional suppression of SKP2, which degrades p27 and p21. Rare cells escaping senescence by restoring SKP2 expression display genomic instability. In > 200 cancer cell lines and in primary circulating tumor cells, SETD1A expression correlates with genes promoting mitosis and cell cycle suggesting a broad role in suppressing senescence induced by aberrant mitosis. Thus, SETD1A is essential to maintain mitosis and proliferation and its suppression unleashes the tumor suppressive effects of senescence.


Assuntos
Senescência Celular/fisiologia , Regulação da Expressão Gênica/fisiologia , Histona-Lisina N-Metiltransferase/metabolismo , Mitose/fisiologia , Linhagem Celular Tumoral , Histona-Lisina N-Metiltransferase/genética , Histonas , Humanos , Metilação , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo
5.
Genes Dev ; 33(13-14): 814-827, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31171703

RESUMO

Alternative lengthening of telomeres (ALT) is a telomerase-independent telomere maintenance mechanism that occurs in a subset of cancers. One of the hallmarks of ALT cancer is the excessively clustered telomeres in promyelocytic leukemia (PML) bodies, represented as large bright telomere foci. Here, we present a model system that generates telomere clustering in nuclear polySUMO (small ubiquitin-like modification)/polySIM (SUMO-interacting motif) condensates, analogous to PML bodies, and thus artificially engineered ALT-associated PML body (APB)-like condensates in vivo. We observed that the ALT-like phenotypes (i.e., a small fraction of heterogeneous telomere lengths and formation of C circles) are rapidly induced by introducing the APB-like condensates together with BLM through its helicase domain, accompanied by ssDNA generation and RPA accumulation at telomeres. Moreover, these events lead to mitotic DNA synthesis (MiDAS) at telomeres mediated by RAD52 through its highly conserved N-terminal domain. We propose that the clustering of large amounts of telomeres in human cancers promotes ALT that is mediated by MiDAS, analogous to Saccharomyces cerevisiae type II ALT survivors.


Assuntos
Núcleo Celular/metabolismo , DNA/biossíntese , Leucemia Promielocítica Aguda/fisiopatologia , Mitose , Proteína Rad52 de Recombinação e Reparo de DNA/metabolismo , RecQ Helicases/metabolismo , Homeostase do Telômero/genética , Motivos de Aminoácidos , Linhagem Celular Tumoral , Expressão Gênica , Humanos , Leucemia Promielocítica Aguda/genética , Fenótipo , Transporte Proteico , Proteína SUMO-1/metabolismo , Telômero/genética , Telômero/metabolismo
6.
Nat Commun ; 10(1): 1931, 2019 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-31036804

RESUMO

Polycomb group (PcG) proteins play critical roles in the epigenetic inheritance of cell fate. The Polycomb Repressive Complexes PRC1 and PRC2 catalyse distinct chromatin modifications to enforce gene silencing, but how transcriptional repression is propagated through mitotic cell divisions remains a key unresolved question. Using reversible tethering of PcG proteins to ectopic sites in mouse embryonic stem cells, here we show that PRC1 can trigger transcriptional repression and Polycomb-dependent chromatin modifications. We find that canonical PRC1 (cPRC1), but not variant PRC1, maintains gene silencing through cell division upon reversal of tethering. Propagation of gene repression is sustained by cis-acting histone modifications, PRC2-mediated H3K27me3 and cPRC1-mediated H2AK119ub1, promoting a sequence-independent feedback mechanism for PcG protein recruitment. Thus, the distinct PRC1 complexes present in vertebrates can differentially regulate epigenetic maintenance of gene silencing, potentially enabling dynamic heritable responses to complex stimuli. Our findings reveal how PcG repression is potentially inherited in vertebrates.


Assuntos
Cromatina/metabolismo , Epigênese Genética , Inativação Gênica , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 2/genética , Processamento de Proteína Pós-Traducional , Animais , Linhagem Celular , Cromatina/química , Retroalimentação Fisiológica , Histonas/genética , Histonas/metabolismo , Padrões de Herança , Camundongos , Mitose , Células-Tronco Embrionárias Murinas/citologia , Células-Tronco Embrionárias Murinas/metabolismo , Complexo Repressor Polycomb 1/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Transcrição Genética
7.
Indian J Cancer ; 56(2): 135-143, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31062732

RESUMO

INTRODUCTION: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. We analyzed the clinicopathological features, resectability, immunohistochemical markers, and various factors predictive of disease recurrence and survival. MATERIALS AND METHODS: Retrospective analysis of prospectively maintained database of GIST patients managed from 2005 to 2016 was done. Size, site, malignant potential, nuclear pleomorphism, histopathological variety, immunohistochemical markers, type of surgery, and adjuvant imatinib therapy were analyzed. RESULTS: Ninety-two patients with GIST were analyzed. Immunohistochemistry showed positivity for c-kit (82.4%), DOG1 (75%), and PDGFR-α (79%). Among 16 patients with c-kit-negative tumors, 10 patients were positive for DOG1, PDGFR-α, or both. The most common primary site was stomach (44, 47.8%) followed by small bowel (17, 18.5%) and duodenum (14, 15.2%). Of 92 patients, 80 (87%) underwent R0 resection with organ sparing resection in 56 (70%) patients. Seventeen (21.3%) patients showed recurrence at a median follow-up of 6 years. Median and 5-year overall survival (OS) was 36 months (12-120) and 75%, respectively, and 5-year RFS was 81.8%. On univariate analysis, size, mitotic activity, malignant potential, and nuclear pleomorphism were predictors of recurrence. However, on multivariate analysis, only nuclear pleomorphism was significant. CONCLUSIONS: GISTs had a wide spectrum of presentation, and immunohistopathological features with organ sparing resection were conceivable in maximum. Nuclear pleomorphism may be considered as an important variable to predict recurrence in addition to malignant potential of tumors.


Assuntos
Biomarcadores Tumorais/genética , Tumores do Estroma Gastrointestinal/genética , Imuno-Histoquímica , Recidiva Local de Neoplasia/genética , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Anoctamina-1/genética , Criança , Feminino , Tumores do Estroma Gastrointestinal/tratamento farmacológico , Tumores do Estroma Gastrointestinal/epidemiologia , Tumores do Estroma Gastrointestinal/patologia , Humanos , Mesilato de Imatinib/administração & dosagem , Masculino , Pessoa de Meia-Idade , Mitose/genética , Proteínas de Neoplasias/genética , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/epidemiologia , Recidiva Local de Neoplasia/patologia , Intervalo Livre de Progressão , Proteínas Proto-Oncogênicas c-kit/genética , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Estudos Retrospectivos , Adulto Jovem
8.
Cell Mol Life Sci ; 76(18): 3543-3551, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31129857

RESUMO

Maintenance of genomic stability during cell division is one of the most important cellular tasks, and it critically depends on the faithful replication of the genetic material and its equal partitioning into daughter cells, gametes, or spores in the case of yeasts. Defective mitotic spindle assembly and disassembly both result in changes in cellular ploidy that ultimately impinge proliferation fitness and might increase tumor malignancy. Although a great progress has been made in understanding how spindles are assembled to orchestrate chromosome segregation, much less is known about how they are disassembled once completed their function. Here, we review two recently uncovered mechanisms of spindle disassembly that operate at different stages of the fission yeast life cycle.


Assuntos
Schizosaccharomyces/metabolismo , Fuso Acromático/fisiologia , Transporte Ativo do Núcleo Celular , Instabilidade Genômica , Carioferinas/metabolismo , Meiose , Mitose , Membrana Nuclear/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo
9.
Dev Genes Evol ; 229(4): 137-145, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31119364

RESUMO

Computer-assisted 4D manual cell tracking has been a valuable method for understanding spatial-temporal dynamics of embryogenesis (e.g., Stach & Anselmi BMC Biol, 13(113), 1-11 2015; Vellutini et al. BMC Biol, 15(33), 1-28 2017; Wolff et al. eLife, 7, e34410 2018) since the method was introduced in the late 1990s. Since two decades SIMI® BioCell (Schnabel et al. Dev Biol, 184, 234-265 1997), a software which initially was developed for analyzing data coming from the, at that time new technique of 4D microscopy, is in use. Many laboratories around the world use SIMI BioCell for the manual tracing of cells in embryonic development of various species to reconstruct cell genealogies with high precision. However, the software has several disadvantages: limits in handling very large data sets, the virtually no maintenance over the last 10 years (bound to older Windows versions), the difficulty to access the created cell lineage data for analyses outside SIMI BioCell, and the high cost of the program. Recently, bioinformatics, in close collaboration with biologists, developed new lineaging tools that are freely available through the open source image processing platform Fiji. Here we introduce a software tool that allows conversion of SIMI BioCell lineage data to a format that is compatible with the Fiji plugin MaMuT (Wolff et al. eLife, 7, e34410 2018). Hereby we intend to maintain the usability of SIMI BioCell created cell lineage data for the future and, for investigators who wish to do so, facilitate the transition from this software to a more convenient program.


Assuntos
Invertebrados/citologia , Software , Animais , Linhagem da Célula , Desenvolvimento Embrionário , Invertebrados/classificação , Invertebrados/embriologia , Masculino , Mitose
10.
Tumour Biol ; 41(5): 1010428319848612, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31074363

RESUMO

Aurora kinases play critical roles in regulating several processes pivotal for mitosis. Radotinib, which is approved in South Korea as a second-line treatment for chronic myeloid leukemia, inhibits the tyrosine kinase BCR-ABL and platelet-derived growth factor receptor. However, the effects of radotinib on Aurora kinase expression in acute myeloid leukemia are not well studied. Interestingly, the cytotoxicity of acute myeloid leukemia cells was increased by radotinib treatment. Radotinib significantly decreased the expression of cyclin-dependent kinase 1 and cyclin B1, the key regulators of G2/M phase, and inhibited the expression of Aurora kinase A and Aurora kinase B in acute myeloid leukemia cells. In addition, radotinib decreased the expression and binding between p-Aurora kinase A and TPX2, which are required for spindle assembly. Furthermore, it reduced Aurora kinase A and polo-like kinase 1 phosphorylation and suppressed the expression of α-, ß-, and γ-tubulin in acute myeloid leukemia cells. Furthermore, radotinib significantly suppressed the key regulators of G2/M phase including cyclin B1 and Aurora kinase A in a xenograft animal model. Therefore, our results suggest that radotinib can abrogate acute myeloid leukemia cell growth both in vitro and in vivo and may serve as a candidate agent or a chemosensitizer for treating acute myeloid leukemia.


Assuntos
Aurora Quinase A/antagonistas & inibidores , Benzamidas/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Leucemia Mieloide Aguda/patologia , Mitose/efeitos dos fármacos , Pirazinas/farmacologia , Animais , Apoptose , Aurora Quinase A/metabolismo , Ciclo Celular , Proliferação de Células , Humanos , Leucemia Mieloide Aguda/tratamento farmacológico , Leucemia Mieloide Aguda/metabolismo , Masculino , Camundongos , Camundongos Nus , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Células Tumorais Cultivadas , Ensaios Antitumorais Modelo de Xenoenxerto
11.
J Med Life ; 12(1): 30-33, 2019 Jan-Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31123522

RESUMO

Glomus tumors are frequently associated with pain, tenderness and cold sensitivity. We report the diagnosis and successful surgical management of a case of a classic glomus tumor in a young woman. The clinical diagnosis was made on the basis of medical history and MRI findings. The lesion was excised via a dorsolateral subungual approach, leading to the complete resolution of symptoms. Histology confirmed the lesion to be a glomus tumor. Glomus tumors are painful subungual lesions. They produce a throbbing or lancinating local discomfort, cold-sensitivity, and severe pain following minor trauma. The diagnosis is confirmed by histology, but the clinical diagnosis is highly suggestive. Complete excision will usually relieve pain. Recurrence is common following incomplete resection.


Assuntos
Dedos/patologia , Tumor Glômico/patologia , Dor/etiologia , Adulto , Antígenos CD34/metabolismo , Proliferação de Células , Feminino , Tumor Glômico/diagnóstico por imagem , Tumor Glômico/cirurgia , Humanos , Antígeno Ki-67/metabolismo , Imagem por Ressonância Magnética , Mitose , Polegar/diagnóstico por imagem , Polegar/cirurgia
12.
Anticancer Res ; 39(5): 2251-2258, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31092416

RESUMO

Cancer is characterized by uncontrolled cell proliferation due to the aberrant activity of various proteins. Cell cycle-related proteins are thought to be important in several functions, such as proliferation, invasion and drug resistance in human malignancies. Never in mitosis gene A-related kinase 2 (NEK2) is a cell cycle-related protein. NEK2 is highly expressed in various tumor types and cancer cell lines. NEK2 expression is correlated with rapid relapse and poor outcome in multiple cancer types. Several researchers have demonstrated that NEK2 inhibition results in anticancer effects against many types of cancers, both in vitro and in vivo. Recent research strongly indicates the advantages of NEK2-targeted therapy for cancer. This review focuses on the current understanding of NEK2 in cancer and the rationale of a xenograft cancer model for cancer treatment. A possible therapeutic strategy, such as inhibitor and nucleic acid medicine targeting of NEK2, is also discussed.


Assuntos
Resistencia a Medicamentos Antineoplásicos/genética , Quinases Relacionadas a NIMA/genética , Neoplasias/genética , Animais , Ciclo Celular/genética , Proliferação de Células/genética , Humanos , Camundongos , Mitose/genética , Quinases Relacionadas a NIMA/antagonistas & inibidores , Quinases Relacionadas a NIMA/uso terapêutico , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Ensaios Antitumorais Modelo de Xenoenxerto
13.
Nat Genet ; 51(5): 824-834, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31036964

RESUMO

Chromosome segregation errors cause aneuploidy and genomic heterogeneity, which are hallmarks of cancer in humans. A persistent high frequency of these errors (chromosomal instability (CIN)) is predicted to profoundly impact tumor evolution and therapy response. It is unknown, however, how prevalent CIN is in human tumors. Using three-dimensional live-cell imaging of patient-derived tumor organoids (tumor PDOs), we show that CIN is widespread in colorectal carcinomas regardless of background genetic alterations, including microsatellite instability. Cell-fate tracking showed that, although mitotic errors are frequently followed by cell death, some tumor PDOs are largely insensitive to mitotic errors. Single-cell karyotype sequencing confirmed heterogeneity of copy number alterations in tumor PDOs and showed that monoclonal lines evolved novel karyotypes over time in vitro. We conclude that ongoing CIN is common in colorectal cancer organoids, and propose that CIN levels and the tolerance for mitotic errors shape aneuploidy landscapes and karyotype heterogeneity.


Assuntos
Instabilidade Cromossômica , Neoplasias Colorretais/genética , Aneuploidia , Linhagem Celular Tumoral , Segregação de Cromossomos , Neoplasias Colorretais/patologia , Variações do Número de Cópias de DNA , Humanos , Imagem Tridimensional , Cariótipo , Cariotipagem , Instabilidade de Microssatélites , Mitose/genética , Mutação , Organoides/patologia , Análise de Célula Única
14.
PLoS Genet ; 15(4): e1008121, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-31034473

RESUMO

Endocycle is a commonly observed cell cycle variant through which cells undergo repeated rounds of genome DNA replication without mitosis. Endocycling cells arise from mitotic cells through a switch of the cell cycle mode, called the mitotic-to-endocycle switch (MES), to initiate cell growth and terminal differentiation. However, the underlying regulatory mechanisms of MES remain unclear. Here we used the Drosophila steroidogenic organ, called the prothoracic gland (PG), to study regulatory mechanisms of MES, which is critical for the PG to upregulate biosynthesis of the steroid hormone ecdysone. We demonstrate that PG cells undergo MES through downregulation of mitotic cyclins, which is mediated by Fizzy-related (Fzr). Moreover, we performed a RNAi screen to further elucidate the regulatory mechanisms of MES, and identified the evolutionarily conserved chaperonin TCP-1 ring complex (TRiC) as a novel regulator of MES. Knockdown of TRiC subunits in the PG caused a prolonged mitotic period, probably due to impaired nuclear translocation of Fzr, which also caused loss of ecdysteroidogenic activity. These results indicate that TRiC supports proper MES and endocycle progression by regulating Fzr folding. We propose that TRiC-mediated protein quality control is a conserved mechanism supporting MES and endocycling, as well as subsequent terminal differentiation.


Assuntos
Ciclo Celular , Chaperoninas/metabolismo , Drosophila/fisiologia , Mitose , Animais , Ciclo Celular/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Ecdisona/biossíntese , Larva , Mitose/genética , Modelos Biológicos , Transporte Proteico , Interferência de RNA
15.
Methods Cell Biol ; 151: 29-36, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30948013

RESUMO

I happen to have been trained in cell and developmental biology in the early 1970s, which was near the beginning of the explosive growth of the field of cell biology. The American Society for Cell Biology had been founded in 1960 and so the field was in its early days. Cell biology research was dominated by the use of the electron microscope and by protein biochemistry. Molecular biology and the use of genetics were in their infancy. When we track the path of discoveries in cell biology contributed by research using echinoderm eggs, we follow the development of new technologies in genetics, molecular biology, biochemistry and biophysics, bioengineering, and imaging. The changes in approaches and methods have led to many key discoveries in cell biology through the use of sea urchin, sand dollar and sea star eggs. These include the discovery of cyclin, cytoplasmic dynein, rho activation for cytokinesis, new membrane addition as a late event in cytokinesis, multiple kinesins playing multiple roles, how flagella beat, the dynamics of microtubules in the mitotic apparatus, control over centrosomes and cell cycle checkpoints, the process of nuclear envelope breakdown for cell division, the discovery of 1-methyl adenine (hormones) as the trigger for meiotic maturation, Ca++ transients controlling cell activation and exocytosis among others. What I hope to provide in this perspective is to highlight some of those wonderful discoveries as my own career evolved to contribute to the field.


Assuntos
Biologia Celular/história , Equinodermos/crescimento & desenvolvimento , Desenvolvimento Embrionário/genética , Óvulo/crescimento & desenvolvimento , Animais , Centrossomo/metabolismo , Citocinese/genética , Equinodermos/genética , Fertilização/genética , História do Século XX , História do Século XXI , Mitose/genética
16.
Nat Commun ; 10(1): 1761, 2019 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-30988289

RESUMO

During mitosis, tension develops across the centromere as a result of spindle-based forces. Metaphase tension may be critical in preventing mitotic chromosome segregation errors, however, the nature of force transmission at the centromere and the role of centromere mechanics in controlling metaphase tension remains unknown. We combined quantitative, biophysical microscopy with computational analysis to elucidate the mechanics of the centromere in unperturbed, mitotic human cells. We discovered that the mechanical stiffness of the human centromere matures during mitotic progression, which leads to amplified centromere tension specifically at metaphase. Centromere mechanical maturation is disrupted across multiple aneuploid cell lines, leading to a weak metaphase tension signal. Further, increasing deficiencies in centromere mechanical maturation are correlated with rising frequencies of lagging, merotelic chromosomes in anaphase, leading to segregation defects at telophase. Thus, we reveal a centromere maturation process that may be critical to the fidelity of chromosome segregation during mitosis.


Assuntos
Centrômero/fisiologia , Segregação de Cromossomos/fisiologia , Mitose/fisiologia , Aneuploidia , Linhagem Celular Tumoral , Células HeLa , Humanos , Metáfase , Modelos Biológicos , Fuso Acromático
17.
Science ; 364(6435): 52-56, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30948545

RESUMO

In multicellular organisms, the entry into meiosis is a complex process characterized by increasing meiotic specialization. Using single-cell RNA sequencing, we reconstructed the developmental program into maize male meiosis. A smooth continuum of expression stages before meiosis was followed by a two-step transcriptome reorganization in leptotene, during which 26.7% of transcripts changed in abundance by twofold or more. Analysis of cell-cycle gene expression indicated that nearly all pregerminal cells proliferate, eliminating a stem-cell model to generate meiotic cells. Mutants defective in somatic differentiation or meiotic commitment expressed transcripts normally present in early meiosis after a delay; thus, the germinal transcriptional program is cell autonomous and can proceed despite meiotic failure.


Assuntos
Regulação da Expressão Gênica de Plantas , Meiose/genética , Pólen/citologia , Pólen/crescimento & desenvolvimento , Zea mays/citologia , Zea mays/crescimento & desenvolvimento , Diferenciação Celular , Mitose/genética , Mutação , Pólen/metabolismo , Análise de Sequência de RNA , Análise de Célula Única , Transcrição Genética , Transcriptoma , Zea mays/genética
18.
Dev Cell ; 48(6): 864-872.e7, 2019 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-30827898

RESUMO

Dynamic coupling of microtubule ends to kinetochores, built on the centromeres of chromosomes, directs chromosome segregation during cell division. Here, we report that the evolutionarily ancient kinetochore-microtubule coupling machine, the KMN (Knl1/Mis12/Ndc80-complex) network, plays a critical role in neuronal morphogenesis. We show that the KMN network concentrates in microtubule-rich dendrites of developing sensory neurons that collectively extend in a multicellular morphogenetic event that occurs during C. elegans embryogenesis. Post-mitotic degradation of KMN components in sensory neurons disrupts dendritic extension, leading to patterning and functional defects in the sensory nervous system. Structure-guided mutations revealed that the molecular interface that couples kinetochores to spindle microtubules also functions in neuronal development. These results identify a cell-division-independent function for the chromosome-segregation machinery and define a microtubule-coupling-dependent event in sensory nervous system morphogenesis.


Assuntos
Cinetocoros/metabolismo , Microtúbulos/metabolismo , Morfogênese , Sistema Nervoso/embriologia , Sistema Nervoso/metabolismo , Células Receptoras Sensoriais/metabolismo , Animais , Caenorhabditis elegans/embriologia , Proteínas de Caenorhabditis elegans/metabolismo , Dendritos/metabolismo , Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário , Mitose
19.
Cell Mol Gastroenterol Hepatol ; 7(3): 533-554, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30827941

RESUMO

BACKGROUND & AIMS: Loss of leucine-rich repeat-containing G-protein-coupled receptor 5-positive crypt base columnar cells provides permissive conditions for different facultative stem cell populations to dedifferentiate and repopulate the stem cell compartment. In this study, we used a defensin α4-Cre recombinase (Defa4Cre) line to define the potential of Paneth cells to dedifferentiate and contribute to intestinal stem cell (ISC) maintenance during normal homeostasis and after intestinal injury. METHODS: Small intestine and enteroids from Defa4Cre;Rosa26 tandem dimer Tomato (tdTomato), a red fluoresent protein, (or Rosa26 Enhanced Yellow Fluorescent Protein (EYFP)) reporter, Notch gain-of-function (Defa4Cre;Rosa26 Notch Intracellular Domain (NICD)-ires-nuclear Green Fluorescent Protein (nGFP) and Defa4Cre;Rosa26reverse tetracycline transactivator-ires Enhanced Green Fluorescent Protein (EGFP);TetONICD), A Disintegrin and Metalloproteinase domain-containing protein 10 (ADAM10) loss-of-function (Defa4Cre;ADAM10flox/flox), and Adenomatous polyposis coli (APC) inactivation (Defa4Cre;APCflox/flox) mice were analyzed. Doxorubicin treatment was used as an acute intestinal injury model. Lineage tracing, proliferation, and differentiation were assessed in vitro and in vivo. RESULTS: Defa4Cre-expressing cells are fated to become mature Paneth cells and do not contribute to ISC maintenance during normal homeostasis in vivo. However, spontaneous lineage tracing was observed in enteroids, and fluorescent-activated cell sorter-sorted Defa4Cre-marked cells showed clonogenic enteroid growth. Notch activation in Defa4Cre-expressing cells caused dedifferentiation to multipotent ISCs in vivo and was required for adenoma formation. ADAM10 deletion had no significant effect on crypt homeostasis. However, after acute doxorubicin-induced injury, Defa4Cre-expressing cells contributed to regeneration in an ADAM10-Notch-dependent manner. CONCLUSIONS: Our studies have shown that Defa4Cre-expressing Paneth cells possess cellular plasticity, can dedifferentiate into multipotent stem cells upon Notch activation, and can contribute to intestinal regeneration in an acute injury model.


Assuntos
Plasticidade Celular , Integrases/metabolismo , Intestinos/lesões , Intestinos/patologia , Celulas de Paneth/metabolismo , Receptores Notch/metabolismo , alfa-Defensinas/metabolismo , Proteína ADAM10/metabolismo , Adenoma/patologia , Proteína da Polipose Adenomatosa do Colo/metabolismo , Alelos , Animais , Desdiferenciação Celular , Linhagem da Célula , Células Clonais , Doxorrubicina , Deleção de Genes , Homeostase , Hiperplasia , Camundongos , Mitose , Células-Tronco Multipotentes/metabolismo , Organoides/crescimento & desenvolvimento , Organoides/patologia , Regeneração
20.
J Cell Biol ; 218(4): 1086-1088, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30858193

RESUMO

Chromosome alignment is a hallmark of mitosis in metazoans, but the physiological relevance of this orderly behavior has remained unclear. In this issue, Fonseca et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201807228) show that chromosome alignment ensures mitotic fidelity by promoting interchromosomal compaction during anaphase.


Assuntos
Anáfase , Cromossomos , Metáfase , Mitose
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