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J T Lee¹, N Lu

¹Department of Molecular Biology, Massachusetts General Hospital, Boston 02115, USA. lee@molbio.mgh.harvard.edu

|October 16, 1999

Resumen

El gen Tsix regula la opción de inactivación del cromosoma X en los mamíferos. La eliminación de Tsix en células femeninas sesgó la inactivación del cromosoma X, mostrando que Tsix controla la expresión de Xist sin afectar el silenciamiento.

Área de la Ciencia:

Genética La genética.
La epigenética es la epigenética.
Desarrollo de los mamíferos Desarrollo de los mamíferos

Sus antecedentes:

Las células femeninas de mamíferos se someten a una inactivación X, seleccionando al azar un cromosoma X para silenciarlo.
El largo ARN no codificante Xist está regulado hacia arriba en el cromosoma X inactivo.
Se supone que el gen antisenso Tsix regula la expresión de Xist.

Objetivo del estudio:

Para investigar el papel del gen Tsix en el control de la inactivación del cromosoma X.
Para determinar si Tsix regula la expresión de Xist e influye en la elección del cromosoma X.

Principales métodos:

Eliminación dirigida del gen Tsix en células de ratón hembra (XX) y macho (XY).
Análisis del conteo del cromosoma X, la expresión de Xist y los patrones de inactivación.

Principales resultados:

La deficiencia de Tsix no afectó el conteo del cromosoma X en las células XX o XY.
Las células femeninas heterocigotas con deleción de Tsix mostraron una expresión de Xist sesgada y una inactivación preferencial del X mutante.
La capacidad del cromosoma X mutante para bloquear la acumulación de Xist se vio comprometida.

Conclusiones:

Tsix actúa en cis para regular la expresión de Xist y determinar la elección del cromosoma X.
El conteo, la elección y el silenciamiento del cromosoma X son procesos genéticamente separables.
Es probable que distintos factores negativos y positivos medien la selección activa e inactiva del cromosoma X en las células XX y XY.

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