CADHERIN-6 IN THE DEVELOPING MOUSE-BRAIN - EXPRESSION ALONG RESTRICTED CONNECTION SYSTEMS AND SYNAPTIC LOCALIZATION SUGGEST A POTENTIAL ROLE IN NEURONAL CIRCUITRY

Multiple subtypes of the cadherin hemophilic cell-cell adhesion molecu le are expressed differentially in developing and mature brains, each being expressed in restricted neuronal groups, Cadherin-6 (cads) is on e of such cadherins, Recent studies of cads mRNA expression in the pos tnatal mouse forebrain showed that it occurs in neurons constituting a specific subset of thalamocortical connections, Here we analyzed the localization of cads mRNA as well as its protein in the entire central nervous system and also in cranial ganglia of mice at late embryonic to postnatal stages, Our results showed that cads is expressed by a li mited population of neurons or their precursors, which are synapticall y connected to one another, throughout the perinatal stages, and that this expression delineates restricted neuronal circuits from the centr al to peripheral nervous systems, which include subpathways of the aud itory, somatosensory, solitary, vestibular, and olivocerebellar system s, cads proteins were detected in these cads mRNA-positive neurons on the surface of their cell bodies or dendrites as well as in the cytopl asm, Confocal microscopic analysis revealed that the cads protein dist ribution overlapped that of synaptotagmin in synapse forming areas, su ggesting that homotypic cads interactions are involved in synaptic con nections between neurons expressing this protein, These findings suppo rt the idea that cadherin-mediated cell-cell adhesions take part in sp ecific interneuronal connections. (C) 1998 Wiley-Liss, Inc.