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Coordinación del ensamblaje del PIC y la remodelación de la cromatina durante la activación génica inducida por
Evi Soutoglou1, Iannis Talianidis
1Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Post Office Box 1527, 711 10 Herakleion, Crete, Greece.
Science (New York, N.Y.)
|March 9, 2002
Resumen
La remodelación de la cromatina, no el ensamblaje del complejo de preiniciación, define la activación génica. Las histonas acetiltransferasas y el reclutamiento del homólogo de Brahma preceden a la remodelación del nucleosoma y la iniciación de la transcripción en el promotor de la antitripsina alfa1.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Regulación genética Reglamento genético.
- Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina Dinámica de la cromatina
Sus antecedentes:
- Comprender el orden preciso de los eventos durante la iniciación de la transcripción génica es crucial para descifrar la regulación génica.
- La activación del gen humano alfa1 antitripsina (AAT) durante la diferenciación de enterocitos proporciona un modelo para estudiar la dinámica de los promotores.
- Los roles del ensamblaje del complejo de preiniciación, las modificaciones histónicas y la remodelación de la cromatina en el inicio de la transcripción siguen siendo áreas de investigación activa.
Objetivo del estudio:
- Para investigar la secuencia temporal de eventos moleculares en el promotor AAT humano durante la activación génica.
- Determinar el papel de la remodelación de la cromatina en el contexto de la formación del complejo de preiniciación y la iniciación transcripcional.
Principales métodos:
- Análisis del reclutamiento ordenado de factores de transcripción al promotor AAT utilizando técnicas como la inmunoprecipitación de cromatina (ChIP).
- Monitoreo del ensamblaje del complejo de preiniciación, incluida la ARN polimerasa II (Pol II) fosforilada.
- Evaluación de la actividad de las histonas acetiltransferasas (CBP, P/CAF) y el reclutamiento de remodeladores de cromatina (hBrm).
Principales resultados:
- Un complejo de preiniciación completo, incluido el ARN fosforilado Pol II, ensamblado en el promotor antes de la activación transcripcional.
- Se reclutaron las histonas acetiltransferasas CBP y P/CAF, pero la hiperacetilación de histonas se retrasó.
- El reclutamiento del homólogo humano Brahma (hBrm) fue transitorio, seguido de una remodelación del nucleosoma que coincidió con el inicio de la transcripción.
Conclusiones:
- En el promotor AAT humano, la reconfiguración de la cromatina es un paso crítico que define la iniciación de la transcripción.
- La remodelación de la cromatina se produce después del ensamblaje de la maquinaria de transcripción del núcleo (Pol II).
- Esto sugiere un modelo donde el ensamblaje del complejo de preiniciación precede, y la remodelación de la cromatina facilita, la iniciación final de la transcripción.
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