|Cellular processes regulated by FMRP during development
by Sally Till, 5/1/2007
Many of the cognitive and behavioral features of fragile X syndrome emerge during childhood and are associated with abnormal organization of connections in the cerebral cortex. Mutations that disrupt the function of the fragile X mental retardation protein (FMRP) give rise to fragile X syndrome. Yet, while recent work has begun to reveal roles for FMRP in the plasticity of adult brain cells, the mechanisms by which FMRP influences cortical development remain unclear.
We are testing the hypothesis that failure of FMRP signaling during development leads to abnormal
cortical organization. To this end, we are focusing on the development of the rodent primary
somatosensory cortex in a mouse model of fragile X syndrome. This cortical area is an excellent
model system for the study of disorders of cortical development because it contains easily
identifiable and highly organized anatomical structures called "barrels", which emerge and
are refined through a stereotypical sequence of developmental events.
If we find that loss of FMRP function results in abnormal cortical development in mice, we will go on to investigate whether these abnormalities can be reversed by reducing signaling downstream of group 1 metabotropic glutamate receptors, a manipulation that is currently the most promising intervention for fragile X-related symptoms. These studies will help to explain the cause of the developmental delay and the related cognitive deficits commonly associated with fragile X syndrome. This information may aid in treating individuals with fragile X by suggesting whether early childhood diagnosis will be important for subsequent treatments.