Role of Nestin in Mouse Development

Abstract

Although nestin has served as a marker of neural stem/progenitor cells for close to twenty years, its function is still poorly understood. During development, this intermediate filament protein is expressed in many different progenitors including those of the central nervous system, heart, skeletal muscle and kidney. The adult expression of nestin is mainly restricted to the subependymal zone and dentate gyrus of the brain, the neuromuscular junction and renal podocytes. I have used two approaches of gain of function and loss of function to elucidate the role of nestin in vivo. Although I was able to generate transgenic lines in which the transgene was ubiquitously expressed at the RNA level, over-expression of nestin at the protein level was not achieved possibly due to post transcriptional regulation of this gene. My data from loss of function approach indicates that nestin-deficient mice have impaired coordination. Balance and muscle strength are not affected and there are no apparent anatomical defects. I found that nestin deficiency is compatible with normal development of the central nervous system but results in abnormal clustering of acetylcholine receptors in the neuromuscular junctions, similar to the phenotype described for deficiency of cyclin-dependent kinase 5 (Cdk5) a candidate downstream effector of nestin. In renal podocytes, where both nestin and Cdk5 are normally expressed, we found reduced branching and abnormally contoured podocyte processes. To further connect the phenotype of nestin deficiency to Cdk5, I demonstrated that nestin deficiency can rescue maintenance of acetylcholine receptor clusters in the absence of agrin, similar to Cdk5/agrin double knockouts, indicating that the observed nestin deficiency phenotypes are the consequence of aberrant Cdk5 activity.Ph