Salivary mucous gland gene expression: Identifying the gene harboring the sld mutation

As an approach to elucidate mechanisms of cell‐specific gene expression in salivary glands we are studying NFS/N‐ sld mice. These mice harbor a spontaneous autosomal recessive mutation, sld ( s ub l ingual gland d ifferentiation arrest) and display a phenotype first described as attenuated mucous cell expression in sublingual glands (Am. J. Pathol. 132:, 1988). Our laboratory demonstrated (Physiol. Genomics 14:–106, 2003) that mucous cells are affected specifically and that a major consequence of the sld mutation is attenuation of Muc19 transcripts, which encode the major secretory product of sublingual mucous cells. We now report efforts to delineate the gene harboring this mutation. Genetic mapping localized the sld mutation to a “critical region” of approximately 1 Mb within chromosome 15. Bioinformatic analysis of the critical region (NCBI mouse genomic database) revealed 16 transcripts (either known genes, putative genes based on alignment of ESTs, or computer models). Expression profiling of these transcripts by RT‐PCR determined that 5 of the 16 transcripts are expressed in either mutant or wild type neonatal sublingual glands. These results will be presented, as well as those from on‐going quantitative real‐time PCR to determine differential expression of these 5 candidate transcripts between sublingual glands of wild type and mutant mice.