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La competencia para replicarse en el óvulo no fertilizado es conferida por Cdc6 durante la maduración meiotica
Jean-Marc Lemaître1, Stéphane Bocquet, Marcel Méchali
1Institute of Human Genetics, CNRS, Genome Dynamics and Development, 141 Rue de la Cardonille, 34396 Montpellier Cedex 5, France.
Nature
|October 18, 2002
Resumen
En la maduración del huevo de Xenopus, la síntesis de proteínas Cdc6 es esencial para la replicación del ADN. Este proceso, desencadenado durante la maduración, permite al óvulo replicar el ADN antes de la fertilización, siendo Cdc6 el factor clave.
Área de la Ciencia:
- Biología celular Biología celular.
- Biología del desarrollo Biología del desarrollo.
- Biología Molecular Biología Molecular
Sus antecedentes:
- La maduración meiótica es crítica para el desarrollo de los ovocitos, transformando un ovocito inmaduro en un óvulo fertilizable.
- Durante la maduración del ovocito de Xenopus, la capacidad de replicación del ADN se obtiene después de la ruptura de la envoltura nuclear.
- Un inductor específico de síntesis de ADN, ausente en los ovocitos, se traduce durante la maduración.
Objetivo del estudio:
- Para identificar el inductor de síntesis de ADN responsable de la competencia de replicación en los huevos de Xenopus.
- Para aclarar el papel de Cdc6 en el inicio de la replicación del ADN durante la maduración de los ovocitos.
Principales métodos:
- Identificación de Cdc6 como el inductor de la síntesis del ADN.
- Análisis del mRNA maternal cdc6 y el almacenamiento de proteínas en los ovocitos.
- Las inyecciones antisense de oligonucleótidos y la inhibición de la traducción para bloquear la síntesis de Cdc6.
- Experimentos de rescate con el uso de proteína Cdc6 recombinante.
Principales resultados:
- Cdc6 se ha identificado como esencial para el reclutamiento de la helicasa de mantenimiento del minicromosoma (MCM).
- El ARNm maternal cdc6 se almacena, y la proteína Cdc6 se sintetiza durante la maduración.
- La traducción de Cdc6 es necesaria y suficiente para la competencia de replicación del ADN.
- La vía del factor citostático (FC) impide la entrada en la fase S hasta la fecundación.
Conclusiones:
- La traducción de Cdc6 durante la maduración meiotica es el evento crítico que confiere la competencia de replicación del ADN a los huevos de Xenopus.
- Cdc6 actúa como el único factor de replicación necesario y suficiente cuya síntesis está regulada por la traducción.
- La licencia de replicación se produce al final de la meiosis I, pero la LCR inhibe activamente la entrada en la fase S.
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