Promotor elements governing the clustered expression pattern of odorant receptor genes.

Odorant receptor (OR) genes of family mOR262 are only expressed in olfactory sensory neurons (OSNs) segregated in a central patch of the nasal turbinates; they comprise conserved DNA elements upstream of their transcription start sites that are proposed to govern the distinct expression pattern. In mouse lines with a transgene containing the coding sequence and a short upstream region of the mOR262-12 gene, expression was restricted to OSNs that were segregated in the characteristic central patch, although the number of cells varied considerably. Only in one line, the transgene was also expressed in OSNs ectopically positioned outside the patch. The axons of transgene-expressing OSNs co-converged with those expressing the endogenous gene. The transgene was found to be expressed in a mutually exclusive manner and from only one allele indicating that the conserved upstream DNA elements play a critical role in controlling the specific expression pattern of these genes.