HU NEURONAL PROTEINS ARE EXPRESSED IN PROLIFERATING NEUROGENIC CELLS

We have utilized immunochemical techniques to investigate the developm ental expression of the Hu proteins, a neuron-specific family of RNA b inding proteins in vertebrates. Previous work suggests that these prot eins may play an important role in neuronal development and maintenanc e. For the present study, we developed a monoclonal antibody (MAb 16A1 1) that binds specifically to an epitope present in gene products of a ll known Hu genes, including HuD, HuC, and Hel-N1. Using brief pulses (1-2 h) of the DNA precursor analog bromodeoxyuridine (BrdU) in conjun ction with MAb 16All, eve observed Hu(+)/BrdU(+) cells in nascent sens ory and sympathetic ganglia in vivo, and in populations of cultured ne ural crest cells. In addition, a few Hu(+) cells were ambiguously BrdU (+) in the neural tube. We conclude that Hu(+) cells first appear in a vian neurogenic populations immediately before neuronal birthdays in t he peripheral nervous system, and at the time of withdrawal from the m itotic cycle in the central nervous system. Consistent with these conc lusions, we have also observed neural crest-derived cells that are bot h Hu(+) and in metaphase of the cell cycle. We suggest that Hu protein s function early in neurogenic differentiation. (C) 1994 John Wiley an d Sons, Inc.