PROXIMAL REGIONS OF THE OLFACTORY MARKER PROTEIN GENE PROMOTER DIRECTOLFACTORY NEURON-SPECIFIC EXPRESSION IN TRANSGENIC MICE

Olfactory marker protein (OMP) expression is highly restricted to matu re olfactory neurons (ON), Less than 0.3 kb of upstream 5' flanking se quence of the OMP gene directs lacZ expression preferentially to ON in several independently derived lines of transgenic mice, A larger tran sgene with 0.8 kb of upstream flanking sequence also gave lacZ express ion in ON and in a few ectopic sites in the central nervous system (CN S), In addition to the main olfactory epithelium, endogenous OMP is al so expressed in chemosensory neurons of the vomeronasal and septal org ans, and lacZ expression was detected in neurons of these sites as wel l, This confirmed the presence of regulatory sequences in the proximal portion of the OMP gene, Endogenous OMP expression in ON was normal i n all transgenic lines, Strikingly, in several transgenic lines lacZ e xpression was restricted to subsets of ON, In one such line, ON axons were intensely stained for lacZ and projected to a subset of olfactory bulb glomeruli, Although identifiable subsets of ON and their termina tion fields have been described previously, this is the first demonstr ation of this phenomenon in transgenic mice, These lines of transgenic mice thus provide in vivo models for characterization of genetic elem ents regulating developmental and functional organization of the olfac tory neuroepithelium. (C) 1996 Wiley-Liss, Inc.