RESUMEN
Acetylation status of DNA end joining protein Ku70 dictates its function in DNA repair and Bax-mediated apoptosis. Despite the knowledge of HDACs and HATs that are reported to modulate the acetylation dynamics of Ku70, very little is known about proteins that critically coordinate these key modifications. Here, we demonstrate that nuclear matrix-associated protein scaffold/matrix-associated region-binding protein 1 (SMAR1) is a novel interacting partner of Ku70 and coordinates with HDAC6 to maintain Ku70 in a deacetylated state. Our studies revealed that knockdown of SMAR1 results in enhanced acetylation of Ku70, which leads to impaired recruitment of Ku70 in the chromatin fractions. Interestingly, ionizing radiation (IR) induces the expression of SMAR1 and its redistribution as distinct nuclear foci upon ATM-mediated phosphorylation at serine 370. Furthermore, SMAR1 regulates IR-induced G2/M cell cycle arrest by facilitating Chk2 phosphorylation. Alternatively, SMAR1 provides radioresistance by modulating the association of deacetylated Ku70 with Bax, abrogating the mitochondrial translocation of Bax. Thus, we provide mechanistic insights of SMAR1-mediated regulation of repair and apoptosis via a complex crosstalk involving Ku70, HDAC6 and Bax.
Asunto(s)
Antígenos Nucleares/metabolismo , Proteínas de Ciclo Celular/metabolismo , Células/efectos de la radiación , Proteínas de Unión al ADN/metabolismo , Histona Desacetilasas/metabolismo , Proteínas Nucleares/metabolismo , Acetilación/efectos de la radiación , Animales , Antígenos Nucleares/genética , Apoptosis/efectos de la radiación , Puntos de Control del Ciclo Celular/efectos de la radiación , Proteínas de Ciclo Celular/genética , Células/enzimología , Células/metabolismo , Quinasa de Punto de Control 2/metabolismo , Reparación del ADN/efectos de la radiación , Proteínas de Unión al ADN/genética , Histona Desacetilasa 6 , Histona Desacetilasas/genética , Humanos , Autoantígeno Ku , Ratones , Proteínas Nucleares/genética , Fosforilación , Unión Proteica , Radiación Ionizante , Proteína X Asociada a bcl-2/genética , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Non-uniform sampling combined with maximum entropy reconstruction is a powerful technique used in multi-dimensional NMR spectroscopy to reduce sample measurement time. We adapted this technique to the pulse EPR experiment hyperfine sublevel correlation (HYSCORE) and show that experimental times can be shortened by approximately an order of magnitude as compared to conventional linear sampling with negligible loss of information.
