Cellular basis for the differential response of mouse kallikrein genes to hormonal induction

The expression of many mouse kallikrein genes in the salivary gland is sexually dimorphic and inducible in females by administration of testosterone or thyroxine. Induction is slow (3-7 days) and is accompanied by the non-uniform differentiation of the cell type expressing these genes from striated duct (SD) cells (female) to granular convoluted tubule (GCT) cells (male). One kallikrein gene, mGK-6, is expressed at an apparently constant total level in male and female and is not induced by either hormone. In situ hybridization histochemistry shows that all kallikrein genes analyzed exhibit uniform cellular distribution of expression in the SD cells of the female. The hormonally mediated differentiation of some, but not all, of these cells has different effects on kallikrein gene expression--mGK-6 is repressed while other kallikreins are induced--leading to non-uniform distribution of expression.