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El alargamiento de la transcripción por la ARN polimerasa II es estimulado por los transactivadores
1Molecular Genetics of Differentiation Laboratory, Imperial Cancer Research Fund, Lincoln's Inn Fields, London, England.
Cell
|June 3, 1994
Resumen
Los activadores mejoran la expresión génica al aumentar el alargamiento de la ARN polimerasa II. Este proceso mejora la procesividad del complejo de transcripción, permitiendo una lectura eficiente de los sitios de pausa y terminación para una activación genética robusta.
Área de la Ciencia:
- Biología Molecular Biología Molecular
- Regulación genética Reglamento genético.
- La bioquímica es la bioquímica.
Sus antecedentes:
- La transcripción génica es un proceso complejo que implica la iniciación y el alargamiento.
- La ARN polimerasa II (Pol II) es la enzima responsable de la transcripción de los genes que codifican las proteínas.
- Se sabe que las proteínas activadoras influyen en la iniciación de la transcripción.
Objetivo del estudio:
- Investigar el papel de los transactivadores en la estimulación de la fase de alargamiento de la transcripción por la ARN polimerasa II.
- Para determinar si la estimulación mediada por activador de la elongación es crucial para la expresión génica del reportero.
- Para comparar la eficacia de diferentes activadores en la promoción de la elongación de la transcripción y la procesividad.
Principales métodos:
- Utilizó varios transactivadores para estudiar su efecto sobre la actividad de la ARN polimerasa II.
- Evaluó la procesividad de los complejos de transcripción activados y no activados.
- Analizó la capacidad de los complejos de transcripción para superar los sitios de pausa y terminación.
- Se comparó el impacto de diferentes activadores (por ejemplo, GAL4-VP16, GAL4-E1a, GAL4-AH) en la eficiencia de alargamiento.
Principales resultados:
- Se encontró que una variedad de transactivadores estimulan el alargamiento de la ARN polimerasa II.
- Los complejos de transcripción activados exhibieron una alta procesividad, leyendo eficientemente a través de sitios de pausa y terminación.
- Complejos de transcripción no activados o "apagados" predominantemente detenidos prematuramente.
- Diferentes activadores demostraron diferentes grados de estimulación de la procesividad, siendo GAL4-VP16 y GAL4-E1a más efectivos que GAL4-AH.
- Se demostró que la estimulación de la elongación es tan crítica como la estimulación de iniciación para la activación del gen reportero.
Conclusiones:
- Las proteínas activadoras juegan un papel importante en la promoción de la elongación de la ARN polimerasa II.
- La competencia de alargamiento mejorada es una función clave de los activadores, que afecta la expresión génica general.
- La capacidad de la polimerasa II para alargarse de manera eficiente está regulada por activadores en conjunto con factores generales de transcripción, lo que sugiere que es parte integral del paso de iniciación.
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