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Un punto de control de ensamblaje de husillo dependiente de la cinasa MAP en extractos de huevo de Xenopus
1Department of Physiology, University of California, San Francisco 94143-0444.
Cell
|November 4, 1994
Resumen
Los extractos de huevo de Xenopus normalmente carecen de puntos de control del ciclo celular. Sin embargo, las altas concentraciones de esperma inducen la detención mitótica mediante la despolimerización de los microtúbulos, lo que requiere la actividad de la proteína activada por mitógeno (MAP) quinasa.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología Molecular Biología Molecular
- Biología del desarrollo Biología del desarrollo.
Sus antecedentes:
- Los embriones tempranos de Xenopus y los extractos de huevo generalmente carecen del punto de control de complejo / ciclosoma (APC / C) que promueve la anafase.
- Este punto de control normalmente impide la entrada en anafase hasta que el ensamblaje del husillo esté completo.
Objetivo del estudio:
- Para investigar los mecanismos de detención mitótica en extractos de huevo de Xenopus bajo condiciones específicas.
- Para determinar el papel de la proteína kinasa activada por mitógeno (MAP) en la regulación del ciclo celular en estos extractos.
Principales métodos:
- Utilizando extractos de huevo de Xenopus con altas densidades de núcleos de esperma para inducir la despolimerización de microtúbulos.
- Evaluación de la detención mitótica mediante la medición de la actividad del factor promotor de la maduración (MPF), la degradación de la ciclina B y la activación de la ERK2/MAP quinasa.
- Empleando la fosfatasa específica de la MAP quinasa MKP-1 para sondear la necesidad de la actividad de la MAP quinasa.
Principales resultados:
- Las altas densidades de esperma causaron la despolimerización de los microtúbulos, deteniendo los extractos en la mitosis.
- Los extractos detenidos exhibieron una alta actividad de MPF, fracasaron en la degradación de la ciclina B y mostraron kinasa ERK2/MAP activada.
- La adición de MKP-1 revirtió la detención mitótica, lo que indica que la MAP quinasa es esencial para su establecimiento y mantenimiento.
Conclusiones:
- La detención mitótica en los extractos de huevo de Xenopus puede ser inducida por la despolimerización del huso en altas densidades de esperma.
- La señalización de la quinasa MAP activada es crucial tanto para iniciar como para mantener esta detención mitótica específica.
- El calcio, que normalmente libera el paro mitótico, no afecta este paro mitótico inducido por la despolimerización del huso.
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