Expression of neuroD/BETA2 in mitotic and postmitotic neuronal cells during the development of nervous system

NeuroD/BETA2, a basic helix-loop-helix transcription factor, has been shown to play a role in tissue-specific differentiation of pancreatic and entero endocrine cells, To gain further insight into the function of neuroD/ BETA2 in the nervous system development, we examined the expression pattern of n euroD/ BETA2 during embryonic and postnatal development by using in situ hy bridization, Dynamic changes of neuroD/BETA2 expression in the central nerv ous system were observed during embryogenesis, especially in telencephalon, hippocampus, cerebellum, spinal cord, and olfactory epithelium. Moderate l evel of expression was also detected in developing pancreas in early embryo genesis, Although the neuroD/BETA2 expression in cerebellum and hippocampus increased over time, expression in cerebral cortex, spinal cord, as well a s in fetal pancreas gradually decreased as embryogenesis proceeded. High le vel of the neuroDIBETA2 expression in developing cerebellum and hippocampus persisted throughout postnatal development and remained at a stable level in the adult brain. Interestingly, neuroDIBETA2 expression was detected not only in postmitotic but also in mitotic cells, as was evident in its expre ssion in external granular layer of cerebellum and granule cells of the den tate gyrus during postnatal development. This observation suggests that neu roD/BETA2 may have a unique role in proliferation, differentiation, or both , of granule cells of cerebellum and dentate gyrus. (C) 2000 Wiley-Liss, In c.