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Destrucción de los pequeños bloques de ARN nuclear U2, U4 o U6 que transespalzan en las células del tripanosoma

C Tschudi¹, E Ullu

¹Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.

|May 4, 1990

Resumen

Los pequeños ARN nucleares (ARN sn) son cruciales para el transesplicado en el Trypanosoma brucei. La degradación del snRNA U2, U4 o U6 detiene el transesplicado de los pre-ARNm de alfa-tubulina, estabilizándolos.

Área de la Ciencia:

Biología Molecular Biología Molecular
Parasitología Parasitología.
ARN Biología Biología ARN

Sus antecedentes:

El trans-splicing es un evento vital de procesamiento de ARN en los eucariotas.
Los pequeños ARN nucleares (ARN sn) son componentes conocidos de los espliceosomas en el cis-esplicado.
El papel específico de los snRNA en el transesplicado de Trypanosoma brucei aún no se ha aclarado completamente.

Objetivo del estudio:

Para investigar el papel de los snRNAs específicos en el trans-splicing de los pre-mRNAs de alfa-tubulina en el Trypanosoma brucei.
Para determinar si los snRNAs son esenciales para los primeros pasos de la reacción de trans-splicing.

Principales métodos:

Se utilizaron células permeables de Trypanosoma brucei.
Empleó escisión dirigida al sitio con desoxioligonucleótidos y ARNasa H para degradar los snRNA U2, U4 y U6.
Se analizó el impacto de la degradación del snRNA en los intermediarios y productos de transesplicado, incluidas las estructuras Y y el líder esplicado libre (SL) intrón.

Principales resultados:

La degradación del snRNA U2, U4 o U6 inhibió significativamente el transesplicado del ARN SL y los pre-ARNm de alfa-tubulina.
La ausencia de U snRNAs funcionales abolió la formación de intermediarios y productos de trans-splicing.
Se encontró que las transcripciones de alfa-tubulina producidas sin trans-splicing eran inestables, lo que sugiere que la adición de la secuencia SL confiere estabilidad.

Conclusiones:

Los U snRNAs son esenciales para un paso temprano en el proceso de trans-splicing en Trypanosoma brucei.
Los snRNP U2 y U4/U6 participan directamente en el trans-splicing.
La adición de la secuencia de líder empalmada a través del trans-esplicado estabiliza los pre-ARNm de alfa-tubulina contra la degradación.

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