The major objective of this research program is to provide the applicant with new and intensive training in relavant renal and whole animal physiological studies and a foundation of published work in elucidating aldosterone signaling pathways controlling ion transport criticle to renal physiology. The applicant's long-term goal is to become a successful independent investigator in molecular and cell biological research of the kidney. To achieve this goal, the applicant will be trained in the rich scientific environment of the Texas Medical Center under the close sponsorship of Dr. Bruce Kone, an expert in these areas. The scientific aims of the proposal are to model the molecular action of aldosterone on the epithelial Na+ channel in the collecting duct. Aldosterone is a major regulator of Na+ and acid-base balance and control of blood pressure.
The specific aims are to define a novel signaling cascade initiated by aldosterone, via AF9a phosphorylation by SGK1 and H3 K79 methylation by mDotla to transcriptional activation of ENaC in mIMCDS cells and to reveal AF9a and mDotl a as novel physiological targets of aldosterone in regulating ENaC transcription in vivo in mice. mIMCDS cells have been shown to respond to aldosterone and express SGK1, AF9a, mDotl a and ENaC. A wide range of molecular approaches including chromatin immunoprecipitation, real-time RTqPCFt nuclear run-on assays and renal physiological assays (ion transport and urinary electrolyte) will be applied to achieve the goals. It is anticipated that 1) AF9a will identified as an early repressed target by aldosterone action, a novel physiological substrate of SGK1, the first non-histone protein interacting with mDotla and the first protein modulating H3 K79 methylation in a targeted manner; 2) Dotla will become the first chromatin-remodeling protein that serves as an integrate component of aldosterone signaling pathway; 3) ENaC will become the first immediate downstream target of AF9a. Collectively this work will poise the applicant to be an innovative independent scientist in renal signaling and ion transport.
