IDENTIFICATION AND CHARACTERIZATION OF TENP, A GENE TRANSIENTLY EXPRESSED BEFORE OVERT CELL-DIFFERENTIATION DURING NEUROGENESIS

The initiation of cellular differentiation in the vertebrate central n ervous system is a cascade of regulated gene expression events involvi ng both intrinsic and extrinsic factors, Currently, the molecular even ts underlying the developmental transition from the cessation of cell proliferation to the onset of cell differentiation during neurogenesis are still poorly understood, We have identified a gene, tenp, which i s likely to play a role during the transition, tenp mRNA was detected in the developing retina and brain, but not in the heart, kidney, or l iver, Anatomically, cells expressing tenp formed a narrow strip at the boundary between the ventricular zone (consisting of proliferating ce lls) and the intermediate zone (occupied by postmitotic, differentiati ng cells), Further analysis showed that they were bromodeoxyuridine ne gative and thus postmitotic, yet without apparent differentiation such as the expression of microtubule-associated protein (MAP2) and neurof ilament (NF68), When expressed in chicken embryonic fibroblast cells t hrough transfection, Tenp protein was immunodetected in membrane fract ions, implying that Tenp might be a membrane protein as predicted by a computer analysis of its primary sequence, Our data suggested that te np might be involved in an early neurogenic event that existed transie ntly after terminal mitosis, yet before the overt differentiation of n eural precursor cells, (C) 1998 John Wiley & Sons, Inc.