EFFECTS OF THYROID-HORMONE ON THE ANDROGENIC EXPRESSION OF KAP GENE IN MOUSE KIDNEY

The kidney androgen-regulated protein (KAP) gene exhibits a cell-speci fic hormonal regulation of its expression in the epithelial cells of p roximal tubules of mouse kidney, where T-3 is required for constitutiv e expression in the straight segments and androgens for expression in the convoluted ones. By using different models of hypothyroidism, we d emonstrate that maximal androgen-mediated induction of the gene depend s on thyroid hormone as well. This constitutes a specific event, since vitamin D-3 cannot mimic the effects of T-3, albeit their remarkable functional relationship. It is also shown that while congenital hypoth yroid hyt/hyt male mice, exposed to maternal T-3 in the gestational pe riod, exhibit diminished but existent androgen-dependent cortical resp onses, mice exposed to goitrogens during gestation and postnatally are unable to express the gene even at postnatal day ninety. Impairment o f KAP cortical expression in hypothyroid animals does not correlate wi th lower levels of androgens or androgen receptor expression.