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Describing a Transcription Factor Dependent Regulation of the MicroRNA Transcriptome
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El control transcripcional de la expresión génica por microARN
Basel Khraiwesh1, M Asif Arif, Gotelinde I Seumel
1Plant Biotechnology, Faculty of Biology, University of Freiburg, Schaenzlestrasse 1, 79104 Freiburg, Germany.
Cell
|January 21, 2010
Resumen
Los microARN (miRNA) normalmente silencian los genes después de la transcripción. En el musgo, una mutación específica reveló que los miRNA también inician el silenciamiento epigenético a través de la metilación del ADN, dependiendo de los niveles de miRNA y ARN objetivo.
Área de la Ciencia:
- Biología vegetal Biología vegetal
- La epigenética es la epigenética.
- Biología molecular La biología molecular.
Sus antecedentes:
- Los microARN (miRNA) son pequeños ARN que regulan la expresión génica post-transcripcionalmente en plantas y animales.
- Si bien se sabe que los pequeños ARN interferentes (siRNA) inducen el silenciamiento de genes transcripcionales, el papel de los miRNA en este proceso ha sido menos comprendido.
Objetivo del estudio:
- Investigar el papel de los microARN (miRNA) en la regulación de los genes de transcripción.
- Para dilucidar el mecanismo por el cual los miRNA podrían influir en el silenciamiento epigenético.
Principales métodos:
- Utilizando mutantes del musgo Physcomitrella patens que carece del gen DICER-LIKE1b.
- Analizar la maduración del miARN, la escisión del ARN objetivo, los niveles de transcripción y los patrones de metilación del ADN.
- Tratamiento de musgo de tipo silvestre con hormonas para observar la inducción de la vía.
Principales resultados:
- Los mutantes sin DICER-LIKE1b mostraron una maduración normal del miARN pero abolieron la escisión del ARN objetivo, lo que llevó a una reducción de los niveles de transcripción.
- Estos mutantes acumularon duplexos de miRNA: ARN objetivo y exhibieron hipermetilación de los genes objetivo, lo que resultó en el silenciamiento de genes.
- La vía de silenciamiento epigenético observada también se indujo en musgos de tipo salvaje tras el tratamiento hormonal.
Conclusiones:
- Los microARN (miRNA) pueden iniciar el silenciamiento epigenético a través de la metilación del ADN, independientemente de su papel canónico post-transcripcional.
- El inicio de esta vía de silenciamiento epigenético depende de la relación entre el miRNA y su ARN diana.
- Este hallazgo revela una nueva capa de regulación génica por miRNA en las plantas.
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