The specific aims of this project are to: 1) describe normal human pituitary pro-opiomelanocortin (POMC) in biosynthesis and processing; 2) test the hypothesis that differences in synthesis and processing of POMC can be identified between normal and adenomatous (Cushing's Disease pituitary tumors); 3) compare the influences of stimulators/inhibitors on POMC, processing and release in normal and abnormal human pituitaries. Human pituitary tissue (norma, adenomatous Cushing's Disease and adenomatous non-Cushing's Disease) will be obtained at operation, analyzed for molecular species of ACTH/Beta-endorphin by radiommunoassay, enzymatically and mechanically dispersed for study in tissue culture and use in perifusion experiments. Biosynthesis and processing of POMC-derived peptides will be examined by steady-state and pulse-chase labeling schemes using radioactive amino acids and sugars followed by immunoprecipitation and fractionation by gel electrophoresis under dissociating conditions. The character and control of hormone release will be studied with advanced perifusion techniques. Sub-human primate anterior pituitary tissue will be similarly studied to refine our understanding of normal human physiology. Comparisons will be made between normal and adenomatous tissue of rates of POMC production, processing of POMC-derived peptides, and effects of stimulators/inhibitors, (CRF, neurotransmitters, glucocorticoids) on synthesis and release in vitro. The long term goals of the project are to understand normal human POMC biosynthesis, processing, release and regulation and to gain knowledge of differences of these molecular events in adenomatous pituitaries that might provide clues to the pathomechanisms of Cushing's Disease.
