Nature:“Rett综合症”的致病原因


儿童神经发育疾病“Rett综合症”是由MeCP2的突变引起的,后者是调控神经元中的转录的一种蛋白。Michael Greenberg及其同事在MeCP2上发现了一个点,即threonine 308 (T308),其磷酸化是由神经活性调控的。T308磷酸化阻断MeCP2与NCoR“共抑制因子复合物”的相互作用,从而降低MeCP2抑制转录的能力。携带MeCP2 T308突变的小鼠表现出与“Rett综合症”相关的症状,表明这种“依赖于活性的”磷酸化及MeCP2–NCoR相互作用的调控在“Rett综合症”中可能扮演着一个成因作用。

Activity-dependent phosphorylation of MeCP2 threonine 308 regulates interaction with NCoR

Daniel H. Ebert,Harrison W. Gabel,Nathaniel D. Robinson,Nathaniel R. Kastan, Linda S. Hu,Sonia Cohen,Adrija J. Navarro,Matthew J. Lyst,Robert Ekiert, Adrian P. Bird & Michael E. Greenberg

Rett syndrome (RTT) is an X-linked human neurodevelopmental disorder with features of autism and severe neurological dysfunction in females. RTT is caused by mutations in methyl-CpG-binding protein 2 (MeCP2), a nuclear protein that, in neurons, regulates transcription, is expressed at high levels similar to that of histones, and binds to methylated cytosines broadly across the genome. By phosphotryptic mapping, we identify three sites (S86, S274 and T308) of activity-dependent MeCP2 phosphorylation. Phosphorylation of these sites is differentially induced by neuronal activity, brain-derived neurotrophic factor, or agents that elevate the intracellular level of 3′,5′-cyclic AMP (cAMP), indicating that MeCP2 may function as an epigenetic regulator of gene expression that integrates diverse signals from the environment. Here we show that the phosphorylation of T308 blocks the interaction of the repressor domain of MeCP2 with the nuclear receptor co-repressor (NCoR) complex and suppresses the ability of MeCP2 to repress transcription. In knock-in mice bearing the common human RTT missense mutation R306C, neuronal activity fails to induce MeCP2 T308 phosphorylation, suggesting that the loss of T308 phosphorylation might contribute to RTT. Consistent with this possibility, the mutation of MeCP2 T308A in mice leads to a decrease in the induction of a subset of activity-regulated genes and to RTT-like symptoms. These findings indicate that the activity-dependent phosphorylation of MeCP2 at T308 regulates the interaction of MeCP2 with the NCoR complex, and that RTT in humans may be due, in part, to the loss of activity-dependent MeCP2 T308 phosphorylation and a disruption of the phosphorylation-regulated interaction of MeCP2 with the NCoR complex.

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