In light of the ability of CRH-BP to antagonize the biological activity of CRH in vitro, it is hypothesized that the CRH-BP modulates the actions of CRH in the pituitary and central nervous system. This hypothesis is tested by several independent approaches presented in this proposal. First, in situ hybridization histochemistry, immunocytochemistry, and RNase protection assays will be utilized to characterize the in vivo regulation of CRH-BP expression within the HPA axis during development and in response to glucocorticoids and stress, two important modulators of CRH expression and HPA activity. The expression and regulation of CRH-BP will also be examined in CRH-deficient mice. Second, the physiological consequences of increased level of CRH-BP in the anterior pituitary will be assessed in a transgenic mouse model of anterior pituitary CRH-BP overexpression. Third, the physiological consequences of decreased CRH-BP levels will be determined in a mammalian model of CRH-BP deficiency created by targeted mutation of the CRH-BP gene in embryonic stem cells. Together, these studies should allow the investigators to elucidate the physiological role of the CRH-BP in pituitary and brain. Finally, studies on the molecular characterization of CRH-BP gene regulation will be initiated in a number of CRH-BP expressing cell lines.
