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La vinculación de RITS a una transcripción naciente inicia el silenciamiento de genes dependientes de RNAi y
Marc Bühler1, André Verdel, Danesh Moazed
1Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
Cell
|June 6, 2006
Resumen
Atar el complejo RITS a las transcripciones nacientes silencia la expresión génica en la levadura de fisión. Este silenciamiento de la transcripción inducido por ARN requiere RNAi y proteínas de heterocromatina, lo que afecta la regulación génica.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- La epigenética es la epigenética.
- Regulación genética Reglamento genético.
Sus antecedentes:
- El complejo de silenciamiento transcripcional inducido por ARN (RITS) en la levadura de fisión está implicado en la formación de heterocromatina a través de mecanismos dependientes del siRNA.
- Los modelos anteriores propuestos por el RITS apuntan a los cromosomas para iniciar el silenciamiento.
Objetivo del estudio:
- Para investigar el papel del complejo RITS dirigido a las transcripciones nacientes en el silenciamiento de genes.
- Para aclarar los mecanismos y requisitos del silenciamiento transcripcional inducido por ARN.
Principales métodos:
- Conexión de la subunidad Tas3 del RITS con el transcrito del gen ura4+.
- Evaluar el silenciamiento de genes, la dependencia de la vía RNAi, la participación de la proteína heterocromatina, la generación de siRNA y las modificaciones de histonas.
- Analizando la ocupación de la ARN polimerasa II y el impacto de las siRNA nucleasas.
Principales resultados:
- El atado de Tas3 a las transcripciones ura4+ indujo el silenciamiento, dependiente del RNAi y de las proteínas de la heterocromatina (Swi6/HP1, Clr4/Suv39h, Sir2).
- El silenciamiento fue acompañado por la generación de ura4+ siRNA, la metilación de H3K9 y la unión Swi6.
- La siRNA nucleasa Eri1 inhibió la capacidad de silenciamiento de los ura4+ siRNAs recién generados.
- Sorprendentemente, el silenciamiento no alteró la ocupación de la ARN polimerasa II en los loci atados o endógenos.
Conclusiones:
- La orientación de las transcripciones nacientes por RITS media las modificaciones de la cromatina y el silenciamiento de genes.
- Los eventos de procesamiento cotranscripcional son cruciales para el silenciamiento transcripcional inducido por ARN.
- Los mecanismos de silenciamiento pueden funcionar independientemente de los cambios en la ocupación de la ARN polimerasa II.
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