MECP2 expression coincides with age-dependent tactile sensory deficits in a female mouse model for Rett syndrome

Rett syndrome is characterized by an early period of typical development and then, regression of learned motor and speech skills in girls. The underlying mechanisms from normalcy to regression are unclear. Due to random X-chromosome inactivation, female patients of Rett syndrome, and female mouse models of Rett syndrome ( Mecp2 Heterozygous , Het) express a functional copy of wild-type MECP2 protein in half of all mature cells in brain and body. By analyzing wild-type MECP2 expression in the context of whisker tactile sensory perception, here we report compensatory increase in MECP2 protein expression in 6-week-old adolescent Het mice, which display normal levels of perineuronal net expression, mild tactile sensory perception deficit and efficient pup retrieval behavior. Comparatively, 12-week-old adult Het mice display decreased MECP2 expression and significant tactile sensory perception deficits. Thus, we have identified a period of normalcy and regression in this female mouse model, which coincide with variable wild-type expression of MECP2. We speculate that compensatory increases in MECP2 expression in Het brains allows for normal functioning, while the inability to maintain these expression level changes leads to behavioral deficits. ### Competing Interest Statement The authors have declared no competing interest.