PREDOMINANT EXPRESSION OF BRN-2 IN THE POSTMITOTIC NEURONS OF THE DEVELOPING MOUSE NEOCORTEX

The expression of Brn-2, a central nervous systems (CNS)-specific POU domain transcription factor, in the developing mouse neocortex was exa mined with an anti-Brn-2 antibody. Brn-2 protein was first detected in CNS on embryonic day (E) 11.5, and remained strong until E15.5. From E11.5 to postnatal day (P) 0, a high level of Brn-2 expression was obs erved in the subventricular zone, the intermediate zone, and the outer layer of the neocortex, but not in the ventricular zone. In the doubl e-staining experiments, most of the Brn-2 positive cells were also pos itive for NCAM-H, an adhesion molecule specific to post-mitotic neuron s. Furthermore, BrdU-labeling experiments demonstrated the presence of Brn-2 protein exclusively in postmitotic cells. These results indicat ed that, in the developing neocortex, Brn-2 expression is up-regulated after the final cell division. Therefore, this transcription factor m ay be involved in the migration and/or maturation process of the immat ure neuronal cells. (C) Elsevier Science B.V.