Asst. Professor Jason Ridlon
Animal Sciences
University of Illinois
Unknown Location

Monday, April 17, 2017
3:00 pm (CT)
3269 Beckman Institute

Abstract

The gastrointestinal microbiota is now viewed as a virtual metabolic organic. This complex microbial organ has endocrine function, including the generation of steroid hormones reabsorbed by the host. Many of the genes encoding enzymes involved in steroid biotransformations are unknown or poorly characterized. We have identified a bacterial gene cluster responsible for steroid-17,20-desmolase which converts host glucocorticoids to androstanes and androgens. These steroid metabolites are known inhibitors of renal 11β-HSD2, an enzyme whose function is to protect the mineralocorticoid receptor from cortisol. Inhibition of 11β-HSD2 may lead to essential hypertension in some individuals, as evidenced by ingestion of licorice root whose active ingredient, glycyrrhizin, is a potent 11β-HSD2 inhibitor, causing hypertension. Recently, we have determined the structure and made substantial progress toward the catalytic mechanism of an enzymatic “switch” that regulates androstane formation by gut microbes. We have identified potential probiotic gut bacteria which may be useful in preventing formation of pro-hypertensive steroids.