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La oligoadenilación no templada promueve la degradación de las transcripciones escindidas por RISC
Fadia Ibrahim1, Jennifer Rohr, Won-Joong Jeong
1Biological Sciences and Plant Science Initiative, University of Nebraska, Lincoln, NE 68588, USA.
Science (New York, N.Y.)
|December 23, 2006
Resumen
Los investigadores descubrieron MUT68, un gen esencial para la degradación de fragmentos de ARN después del silenciamiento de ARN pequeño interferente (siRNA). Este gen codifica una enzima que ayuda en la descomposición de las transcripciones objetivo, aclarando un paso clave en la interferencia de ARN.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- ARN Biología Biología ARN
- Regulación genética Reglamento genético.
Sus antecedentes:
- El ARN de doble cadena procesado en pequeños ARN interferentes (siRNA) por Dicer e integrado en el complejo de silenciamiento inducido por ARN (RISC) media el silenciamiento de genes en eucariotas.
- La interferencia de ARN (RNAi) es una de las principales vías de silenciamiento de genes, caracterizada principalmente por la degradación de las transcripciones homólogas.
- El destino de los fragmentos de ARN generados después de la escisión mediada por siRNA sigue siendo en gran medida desconocido.
Objetivo del estudio:
- Para investigar los mecanismos moleculares que rigen la desintegración de las transcripciones dirigidas a siRNA.
- Para identificar genes involucrados en el procesamiento posterior a la escisión de fragmentos de ARN en la interferencia de ARN.
- Para aclarar el papel de enzimas específicas en la vía de degradación de fragmentos de ARN escindidos.
Principales métodos:
- Identificación de genes en Chlamydomonas reinhardtii utilizando pruebas genéticas.
- Clonación molecular y caracterización del gen identificado (MUT68).
- Análisis bioquímicos para determinar la actividad enzimática de la proteína MUT68.
Principales resultados:
- Identificación del gen MUT68, esencial para la descomposición eficiente de las transcripciones dirigidas al siRNA.
- MUT68 codifica una polimerasa de poliadenilato no canónica.
- La enzima MUT68 agrega adeninas sin plantilla a los fragmentos de ARN 5' después de la escisión del siRNA, promoviendo su degradación dependiente del exosoma.
Conclusiones:
- MUT68 juega un papel crítico en la vía de interferencia del ARN al facilitar la degradación de los fragmentos de ARN escindidos.
- La actividad de poliadenilación de MUT68 es un paso clave en la orientación de estos fragmentos para la descomposición mediada por exosomas.
- Este hallazgo proporciona nuevos conocimientos sobre el ciclo de vida completo de las moléculas de ARN durante el silenciamiento de genes mediado por ARNi.
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