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La heterocromatina y el ARNi son necesarios para establecer la cromatina CENP-A en los centrómeros
Hernan Diego Folco1, Alison L Pidoux, Takeshi Urano
1Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, 6.34 Swann Building, Edinburgh EH9 3JR, Scotland, UK.
Science (New York, N.Y.)
|January 5, 2008
Resumen
La heterocromatina dirigida por la interferencia de ARN (RNAi) es crucial para el ensamblaje de la cromatina CENP-A y los cinetocoros en los centrómeros de la levadura de fisión. Esta heterocromatina guía el ensamblaje inicial, después del cual la cromatina CENP-A se mantiene epigenéticamente.
Área de la Ciencia:
- La epigenética es la epigenética.
- Biología Molecular Biología Molecular
- Biología de la cromatina Biología de la cromatina
Sus antecedentes:
- La heterocromatina, marcada por la metilación de la histona H3 lisina 9 (H3K9me), recluta la proteína 1 de la heterocromatina (HP1) y se encuentra cerca de la cromatina CENP-A, esencial para el ensamblaje de los cinetocoros.
- La cromatina centromérica, particularmente CENP-A, es vital para la correcta segregación cromosómica durante la división celular.
Objetivo del estudio:
- Investigar el papel de la heterocromatina dirigida por la interferencia de ARN (RNAi) en el ensamblaje de la cromatina CENP-A y los cinetocores en los centrómeros de la levadura de fisión.
- Identificar los factores clave involucrados en el establecimiento y mantenimiento de la heterocromatina centromérica y su relación con el CENP-A.
Principales métodos:
- Utilizó la levadura de fisión como organismo modelo.
- Investigó la función de proteínas clave, incluida la H3K9 metiltransferasa Clr4, la ribonucleasa Dicer, el componente de iniciación inducida por ARN del silenciamiento de genes transcripcionales (RITS) Chp1 y Swi6 (HP1).
- Examinó el requisito de estos factores para el ensamblaje de CENP-A ((Cnp1) y kinetochore en plantillas centroméricas ingenuas.
Principales resultados:
- Se demostró que la heterocromatina dirigida por ARNi que flanquea el dominio cinetocoral central es esencial para promover el CENP-A ((Cnp1) y el ensamblaje de los cinetocoros.
- Se demostró que Clr4, Dicer, Chp1 y Swi6 son necesarios para establecer la cromatina CENP-A ((Cnp1) en nuevas secuencias centroméricas.
- Se encontró que una vez ensamblada, la cromatina CENP-A ((Cnp1) se propaga epigenéticamente independientemente de la heterocromatina.
Conclusiones:
- La heterocromatina dirigida por ARNi centromérico juega un papel crítico en el establecimiento inicial de la cromatina CENP-A y el ensamblaje de kinetocoros.
- Este estudio revela un papel conservado para el RNAi centromérico en la regulación epigenética de la identidad centromérica.
- Los hallazgos destacan una función novedosa para el ARNi en la orientación de la herencia epigenética de la cromatina centromérica.
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