EXPRESSION OF 4 IMMUNOGLOBULIN SUPERFAMILY ADHESION MOLECULES (L1, NR-CAM BRAVO, NEUROFASCIN/ABGP, AND N-CAM) IN THE DEVELOPING MOUSE SPINAL-CORD/

To identify cell adhesion molecules (CAMs) expressed by mammalian moto neurons, we applied the polymerase chain reaction to a murine motor ne uron-like cell line, NSC-34. Using primers derived from a group of L1- related CAMs, we cloned two alternatively spliced forms of mouse L1, w hich differ by a 12-base-pair insert, plus putative murine orthologs o f the chicken cell adhesion molecules Nr-CAM/Bravo and neurofascin. Al l four mRNAs are expressed in NSC-34 cells, but only neurofascin and t he insert-minus form of L1 are expressed in its neuroblastoma parent, N18TG2. Analysis of RNA in neonatal tissues reveals expression largely restricted to the brain and spinal cord. In situ hybridization histoc hemistry of spinal cord shows that motoneurons express L1, Nr-CAM, and neurofascin as well as N-CAM. L1 and N-CAM RNAs are detected througho ut the period studied (from embryonic day [E]11 to postnatal day [P]28 ), whereas Nr-CAM is expressed only at early ages (<E15) and neurofasc in is predominantly expressed postnatally. Moreover, each CAM is expre ssed by distinct subsets of neighboring cells and at distinct times. F or example, Nr-CAM mRNA is present in floor plate cells of embryonic s pinal cord, whereas neurofascin is expressed by a subset of glia postn atally. Finally, we show that each CAM has a distinct spatiotemporal p attern of expression in dorsal root ganglia. (C) 1995 Wiley-Liss, Inc.