Altered microtubule dynamics in Mecp2-deficient astrocytes

Abstract

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by mutations in the gene MECP2 encoding the methyl-CpG binding protein 2. This genetic disease affects predominantly girls and is characterized by a period of normal development that lasts for 8-18 months, followed by neurologic regression affecting both motor and mental abilities. Previous studies performed on brains from RTT subjects and Mecp2-deficient mice showed striking changes in neuronal maturation and dendritic arborization. Recently, we showed that expression of stathmin-like 2 (STMN2) was significantly reduced in fibroblasts from RTT patients, and similar results were obtained in the cerebellum of Mecp2-deficient mice. Because assembly and dynamics of microtubules are known to be modulated by STMN2, we studied microtubule dynamics in brain cells from Mecp2-deficient mice. We observed that Mecp2 deficiency affects microtubule dynamics in astrocytes from Mecp2-deficient mice. Our data reinforce the fact that the loss of Mecp2 in astrocytes may influence the onset and progression of RTT. These results imply that Mecp2 has a stabilizing role in microtubule dynamics and that Mecp2 deficiency, which is associated with STMN2 down-regulation, could lead to impaired microtubule stability, hence explaining the dendritic abnormalities observed in RTT brains.