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La GMP-AMP sintasa cíclica es un sensor de ADN citosólico que activa la vía del interferón tipo I
Lijun Sun1, Jiaxi Wu, Fenghe Du
1Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Science (New York, N.Y.)
|December 22, 2012
Resumen
El ADN citosólico desencadena respuestas inmunes a través de la producción cíclica de GMP-AMP (cGAMP). Los investigadores identificaron la cGAMP sintasa (cGAS) como la enzima responsable, relacionándola con la activación de STING y la producción de interferón.
Área de la Ciencia:
- Inmunología Inmunología.
- Biología Molecular Biología Molecular
- La bioquímica es la bioquímica.
Sus antecedentes:
- La presencia de ADN citoplasmático señala el peligro en las células de mamíferos, activando respuestas inmunes como los interferones de tipo I.
- Los interferones de tipo I son inducidos por el ADN citosólico a través del monofosfato de guanosina-adenosina monofosfato cíclico (cGAMP), que activa la proteína adaptadora STING.
Objetivo del estudio:
- Para identificar la enzima responsable de la síntesis de cGAMP en respuesta al ADN citosólico.
- Para dilucidar el papel de esta enzima en la respuesta inmune del huésped al ADN citosólico.
Principales métodos:
- Se emplearon fraccionamiento bioquímico y espectrometría de masas cuantitativa para identificar la cGAMP sintasa.
- Los experimentos involucraron la sobreexpresión y el derribo de la enzima identificada, junto con modelos de transfección de ADN y de infección por virus de ADN.
Principales resultados:
- Se identificó una nueva cGAMP sintasa (cGAS), perteneciente a la familia de las nucleotidiltransferasas.
- La sobreexpresión de cGAS condujo a la activación dependiente de STING de IRF3 y la producción de interferón-β.
- La desactivación del cGAS inhibió la activación del IRF3 y la inducción del interferón-β en respuesta a los estímulos del ADN.
- Se demostró que el cGAS se une al ADN en el citoplasma y cataliza la síntesis de cGAMP.
Conclusiones:
- cGAS es un sensor de ADN citosólico crítico.
- cGAS sintetiza el segundo mensajero cGAMP, que media la inducción de los interferones.
- Esta vía pone de relieve un mecanismo clave de detección inmune innata de ADN extraño o propio en el citoplasma.
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