ARREST OF CELL-GROWTH BY NECDIN, A NUCLEAR-PROTEIN EXPRESSED IN POSTMITOTIC NEURONS

Necdin is a 325 amino acid residue protein localized to the nuclei of postmitotic neurons, which withdraw permanently from the cell cycle. T o examine whether necdin confers the postmitotic phenotype, necdin cDN A was stably transfected into NIH3T3 cells, in which the protein was c onditionally expressed using a eukaryotic lac repressor-operator expre ssion system. When the transfectants were induced to express ectopic n ecdin, cell growth was arrested without appreciable reduction in cell viability. The expressed necdin molecule was localized to the nuclei o f the transfectants. These results suggest that necdin is a nuclear fa ctor that governs the permanent arrest of cell growth of postmitotic n eurons during development of the nervous systems of vertebrates. (C) 1 995 Academic Press, Inc.