Anaphase Onset does not Require the Microtubule-Dependent Depletion of Kinetochore and Centromere-Binding Proteins

Spindle checkpoint proteins, such as Mad2 and BubR1, and the motors dynein/dynactin and CENP-E usually leave kinetochores prior to anaphase onset by microtubule-dependent mechanisms. Likewise, \u27chromosome passenger proteins\u27 including INCENP are depleted from the centromeres after anaphase onset and then move to the midzone complex, an event that is essential for cytokinesis. Here we test whether the cell cycle changes that occur at anaphase onset require or contribute to the depletion of kinetochore and centromere proteins independent of microtubules. This required the development of a novel non-antibody method to induce precocious anaphase onset in vivo by using a bacterially expressed fragment of the spindle checkpoint protein Mad1 capable of activating the APC/C, called GST-Mad1F10. By injecting PtK1 cells in nocodazole with GST-Mad1F10 and processing the cells for immunofluorescence microscopy after anaphase sister chromatid separation in nocodazole we found that Mad2, BubR1, cytoplasmic dynein, CENP-E and the 3F3/2 phosphoepitope remain on kinetochores. Thus depletion of these proteins (or phosphoepitope) at kinetochores is not required for anaphase onset and anaphase onset does not produce their depletion independent of microtubules. In contrast, both microtubules and anaphase onset are required for depletion of the \u27chromosome passenger\u27 protein INCENP from centromeres, as INCENP does not leave the chromosomes prior to anaphase onset in the presence or absence of microtubules, but does leave the centromeres after anaphase onset in the presence of microtubules

Genome-wide analysis reveals a cell cycle–dependent mechanism controlling centromere propagation

Centromeres are the structural and functional foundation for kinetochore formation, spindle attachment, and chromosome segregation. In this study, we isolated factors required for centromere propagation using genome-wide RNA interference screening for defects in centromere protein A (CENP-A; centromere identifier [CID]) localization in Drosophila melanogaster. We identified the proteins CAL1 and CENP-C as essential factors for CID assembly at the centromere. CID, CAL1, and CENP-C coimmunoprecipitate and are mutually dependent for centromere localization and function. We also identified the mitotic cyclin A (CYCA) and the anaphase-promoting complex (APC) inhibitor RCA1/Emi1 as regulators of centromere propagation. We show that CYCA is centromere localized and that CYCA and RCA1/Emi1 couple centromere assembly to the cell cycle through regulation of the fizzy-related/CDH1 subunit of the APC. Our findings identify essential components of the epigenetic machinery that ensures proper specification and propagation of the centromere and suggest a mechanism for coordinating centromere inheritance with cell division

Polo-Like Kinase Controls Vertebrate Spindle Elongation and Cytokinesis

During cell division, chromosome segregation must be coordinated with cell cleavage so that cytokinesis occurs after chromosomes have been safely distributed to each spindle pole. Polo-like kinase 1 (Plk1) is an essential kinase that regulates spindle assembly, mitotic entry and chromosome segregation, but because of its many mitotic roles it has been difficult to specifically study its post-anaphase functions. Here we use small molecule inhibitors to block Plk1 activity at anaphase onset, and demonstrate that Plk1 controls both spindle elongation and cytokinesis. Plk1 inhibition did not affect anaphase A chromosome to pole movement, but blocked anaphase B spindle elongation. Plk1-inhibited cells failed to assemble a contractile ring and contract the cleavage furrow due to a defect in Rho and Rho-GEF localization to the division site. Our results demonstrate that Plk1 coordinates chromosome segregation with cytokinesis through its dual control of anaphase B and contractile ring assembly

CENP-C recruits M18BP1 to centromeres to promote CENP-A chromatin assembly

CENP-C provides a link between existing CENP-A chromatin and the proteins required for new CENP-A nucleosome assembly

Dual recognition of CENP-A nucleosomes is required for centromere assembly

CENP-C and CENP-N recognize distinct structural elements of CENP-A nucleosomes, providing a foundation for the assembly of other centromere and kinetochore components

The Centromere: Epigenetic Control of Chromosome Segregation during Mitosis

Las instituciones como la nuestra se presta atención integral en salud con excelente calidad a todos los pacientes, por ello se velará por el cuidado de su piel, considerada como la primera línea de defensa del organismo, por lo que se presenta la necesidad de unificar el cuidado de los diversos tipos de heridas, para aplicar la debida técnica aséptica y normatividad que establece el comité de infección: minimizar el riesgo, promover la cicatrización prevenido o disminuir la infección, proteger las heridas contra trauma local, mantener el ambiente húmedo, eliminar la presión, aliviar el dolor, brindar comodidad al paciente, promover auto cuidado, disminuir costros y la estancia hospitalaria. En la Constitución Política de Colombia, se contemplan leyes que regulan, controlan y dictaminan las normas que deben ser cumplidas por instituciones de salud.Tener acceso a la plataforma Moodl