Temporal Expression of Muc19/Smgc Gene Products in Sublingual Glands

Objective: Our goal is to define the temporal postnatal expression of Muc19 and Smgc transcripts in sublingual glands, and further compare glands from male and female mice. Methods: RNA was extracted from sublingual glands of male and female mice at 3-days, 10-days, 4-weeks, 8-weeks, and 18-weeks of age. After DNase I treatment, RNA concentrations were assessed using the Quant-it RNA assay. cDNA was then prepared from each RNA sample using random primers and the purified cDNA quantified using the Quant-it dsDNA assay. The expression levels of Muc19 and Smgc transcripts were determined in each cDNA sample by real time PCR (TaqMan Assays, Applied Biosystems) and the results normalized to Β-actin. Results: Initial results indicate Muc19 levels are stable at 3- and 10-days of age, but increase approximately 10-fold at 4-weeks and remain consistent through 18-weeks. Smgc is present in neonates (3-10 days) and may be as much as 10-fold higher in males than females. At four weeks and older, Smgc levels are 1000-fold less in males, whereas in females levels only decrease 20- to 40-fold. Conclusions: The inverse relationship between Smgc and Muc19 transcript levels with age is consistent with the hypothesis of Smgc functioning as a marker for preacinar cells during sublingual gland development. The pattern of Muc19 expression suggests the glandular mucous cell population is not fully developed until at least 4-weeks of age. The higher expression levels of Smgc in females versus males from 4- to 18-weeks of age are consistent with results in submandibular glands, where Smgc expression in adults is localized primarily to a subpopulation of precursor intercalated duct cells in female glands.

Supported by UFCD Student Summer Research Fellowship and RO1 DE14730 (DC).