GENE EXPRESSION DURING THE DUCT CELL DIFFERENTIATION IN SALIVARY GLANDS

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1)A novel protein expressed in rat sublingual gland : We cloned a novel rat gene expressed primarily in the sublingual gland and named the predicted 503 amino-acid protein SLAMP (sublingual acinar membrane protein). SLAMP had 63% homology with human ERGIC-53-like protein, a member of the family of animal L-type lectins. SLAMP mRNA and protein were expressed predominantly in the mucous acinar cells of sublingual gland. Ultrastructurally, SLAMP was localized to the ER-Golgi intermediate compartment (ERGIC), suggesting that SLAMP functions in the early secretory pathway of glycoproteins. 2)A new method of producing rat polyclonal antibodies with shorter time and lower cost: Producing antibodies usually takes a long time. We developed a new method of producing polyclonal antibodies in less than a month, based on preparation of the recombinant oligopeptides as antigen followed by immunization of rats. Using this method, we produced antisera against ERGIC-53 and confirmed its localization in the ERGIC. 3)A novel submandibular androgen-repressed protein of the mouse: We characterized a cDNA clone derived from the female mouse submandibular gland (SMG). The protein product of this clone had a 165-amino acid protein with a putative signal sequence and was named submandibular androgen-repressed protein (SMARP). In the mouse SMARP mRNA was expressed only in the SMG and exorbital lacrimal gland (LG). The level of SMARP mRNA was 36 times higher in female than male SMG, whereas it was 28 times higher in male than female LG. Furthermore, it was reduced in SMG but increased in LG after administration of testosterone to females or castrated males. SMARP mRNA and protein were predominantly localized in acinar cells in both SMG and lacrimal gland. These results suggested that SMARP is a secretory protein whose expression is regulated by androgens negatively in the SMG and positively in the LG.