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Transiciones de fase en el montaje y la función de los miRISC humanos
Jessica Sheu-Gruttadauria1, Ian J MacRae1
1Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Cell
|March 27, 2018
Resumen
Los complejos de microprocesadores (miRISC) forman gotas separadas por fases a través de las interacciones con las proteínas. Esta condensación acelera la deadenilación de los ARN mensajeros objetivo (ARNm), revelando un nuevo mecanismo para silenciar los genes.
Área de la Ciencia:
- Biología molecular
- La bioquímica
- Biología del ARN
Sus antecedentes:
- Los complejos de microprocesadores (miRISC) son cruciales para la regulación genética a través de los microARN (miRNA).
- La estructura física y el montaje de miRISC han permanecido en gran medida indefinidos.
- Comprender la naturaleza física de miRISC es clave para descifrar sus mecanismos de regulación.
Objetivo del estudio:
- Investigar las propiedades físicas y el montaje de miRISC humano.
- Para aclarar el papel de las interacciones proteína-proteína en la formación de miRISC.
- Determinar las consecuencias funcionales de la condensación de miRISC en el procesamiento del ARN.
Principales métodos:
- Ensayos de separación de fase in vitro con las proteínas miRISC del núcleo Argonaute2 (Ago2) y TNRC6B.
- Imágenes de células vivas para observar la formación de gotas miRISC.
- Análisis bioquímicos del reclutamiento del factor de dedenilación y el secuestro del ARN objetivo.
Principales resultados:
- Los componentes del núcleo humano de miRISC, Ago2 y TNRC6B, se someten a una separación de fase líquido-líquido in vitro y en células.
- La separación de fase es impulsada por interacciones multivalentes entre el dominio rico en GW de TNRC6B y el dominio PIWI de Ago2.
- Las gotas miRISC reclutan factores de dedenilación y aceleran la dedenilación del ARNm objetivo.
Conclusiones:
- La separación de fases mediada por proteínas es una propiedad fundamental del miRISC humano.
- La condensación de miRISC facilita la deadenilación eficiente del ARNm objetivo y el silenciamiento de genes.
- Este mecanismo proporciona información sobre cómo miRISC maneja diversos sustratos de ARNm.
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