Program Director/Principal Investigator (Last, First, Middle): Sigmund, Curt D. PROJECT SUMMARY (See instnjctions): The renin-angiotensin system is a major regulator of blood pressure and electrolyte balance in animals and humans and has been implicated in the genetic basis of essential hypertension. Renin is the rate limiting enzyme cascade and its synthesis is highly regulated at both the transcriptional, post-transcriptional and secretory level. Our efforts ofthe past 15 years have lead to significant advances in our understanding of the transcriptional mechanisms regulating this important gene and have begun coupling transcription to physiology. With the development of new innovative technologies for interrogation of individual genes and proteins in both cells and whole animals, we are now poised for the first time to make important discoveries linking transcriptional events to specific physiological responses and pathways. Studies in the l\/IERIT EXTENSION period will continue to focus on the overall hypothesis: The enhancers found upstream ofthe renin gene along with their cognate transcription factors (and specific ligands), co-activators, and co- repressors play a major role in controlling the cell- and tissue-specificity of expression and the transcriptional responses to physiological cues. We will build upon the progress and major scientific achievements ofthe current budget period to dramatically expand our knowledge on the regulation of renin gene expression by: 1) examining the relevance and role of CREB/ATF and HoxDIO transcription factors on the mechanisms of renin expression in renin expressing cells both in vitro and in vivo; 2) examining cellular and transcriptional mechanisms regulating renin gene by oxidative stress; 3) identifying the function of conserved non-coding sequences upstream ofthe kidney enhancer using cell lines and recombineering followed by BAC-mediated transgenesis; 4) assessing the novel role of micro RNAs (miRNAs) in the regulation of renin in vitro and in vivo; and 5) examining the importance of brain renin in the regulation of hydromineral balance and energy metabolism. RELEVANCE (See instructions): Renin is the first and rate limiting step in the production of angiotensin peptides which have pleiotropic effects on blood pressure, sodium and water homeostasis, sympathetic nervous system and systemic metabolism. These studies will link transcriptional signals regulating the renin gene with physiological endpoints controlling blood pressure and metabolism which may go awry in hypertension. I