Molecular chaperones and their roles in neural cell differentiation.

During the development of the nervous system, a large number of neurons are eliminated through naturally occurring neuronal death. Many morphological and biochemical properties of such dying neurons are reminiscent not only of apoptosis, a type of death involving the action of genetically programmed events, but also of epigenetic phenomena such as oxidative stress. Increasing evidence demonstrates that oxidative stress alters the expression of antioxidant enzymes and enhances expression and/or DNA binding of numerous transcription factors, including heat shock factor. The latter is a transcription factor for specific promoter elements located upstream of the heat shock genes. Heat shock proteins (Hsps) are essential, highly conserved proteins that are needed for normal cell growth and maintenance, and expression of Hsps has been detected during embryogenesis in various organisms. Developmental profiles of Hsps indicate that they are differentially regulated during neural maturation, suggesting a role for Hsps in neural cell differentiation. Their putative function in cell remodeling during migration and differentiation, as well as during postnatal development, a time of extensive cell differentiation, is considered in the present review. Moreover, the function of Hsps in cell signaling, protein transport and the effect of heat shock on neural plate induction and brain development are discussed.