EXPRESSION OF RB, E2F1, CDC2, AND D-CYCLINS, AND B-CYCLINS IN DEVELOPING SPINAL-CORD

The spatial and temporal distribution of transcripts for the tumor sup pressor gene Rb, transcription factor E2F1, cdc2 kinase, cyclins D1, D 2, B1 and B2 during neurogenesis of the spinal cord was determined by in situ hybridization. The Rb and E2F1 transcripts were detectable in proliferating and differentiating cells. By contrast, cdc2, cyclins D1 , BI and B2 are expressed in the ventricular zone where proliferating cells are localized. Cyclin D2 mRNA was detectable only in the margina l zone of the developing neural tube. Electrophoretic mobility shift a nalyses demonstrated a changing pattern of DNA/protein complexes that bind to E2F binding site. These observations suggest that Rb and E2F1 may be involved in the early stages of neuronal differentiation in add ition to the cell cycle regulation.