Aberrant 11 beta-hydroxysteroid dehydrogenase-1 activity in the cpk mouse: Implications for regulation by the Ke 6 gene

Glucocorticoids have been used to create experimental polycystic kidney disease in rodents and to induce cysts in embryonic kidneys cultures. In addition, the plasma corticosterone levels are higher in a heritable murine model of polycystic kidney disease, cph mice, in the first postnatal week. Previously, we had shown that the 11 beta-hydroxysteroid dehydrogenase-1 (11 beta HSD-1) gene is down-regulated in the cph mice in a coordinated pattern with the Ke 6 gene. In this study, we measured the level of 11 beta HSD-1 activity in kidney and Liver tissues of cpk homozygote mice and found a reduction in its activity only in the kidney, not in the liver. The activity of the 11 beta HSD-1 enzyme appears to be tightly correlated to the level of Ke 6 protein in these tissues. We discuss the possibility that the activity of the 11 beta HSD-1 enzyme may be regulated by the Ke 6 enzyme. Ke 6 gene expression has been located to the outer stripe region of rodent kidneys, which is the same region of expression as that for the 11 beta HSD-1 gene. These results suggest that down-regulation of the Ke 6 gene may lead to elevated corticosterone levels, mediated through an inhibition of 11 beta HSD-1 activity.