Cortisol Production Mechanisms in impacting cardiovascular health

Chronically elevated levels of the stress hormone cortisol cause numerous debilitating health conditions and drive a greatly increased risk of cardiovascular disease. Current treatments include resection of the tumors driving steroid overproduction and enzymatic inhibition of the steroid synthesis pathway. Unfortunately, surgical intervention is highly susceptible to recurrence and/or lifelong complications due to hormone replacement therapy while approved steroidogenesis inhibitors fail to improve symptoms for up to 50% of patients and can cause hypertension via increases in cortisol precursors. The long-term goals of the proposed study include developing novel intervention strategies that target cortisol production upstream of steroid synthesis enzymes, thereby precluding overproduction of precursors. The current project aims to identify key signaling organization processes of adrenal protein kinase A (PKA) and assess a candidate strategy to diminish cardiovascular impacts in a genetic stress disorder. PKA is required for cholesterol import into mitochondria, the initiating step in steroidogenesis. Preliminary work has found that knockdown of a PKA-organizing molecule, A-kinase anchoring protein 11 (AKAP11), leads to 50% reduction in the murine cortisol analog corticosterone. The experiments outlined here will 1) identify the molecular mechanisms underlying AKAP11’s impact on adrenal steroid synthesis and 2) determine the impacts of AKAP11 deletion in a mouse model of chronically elevated stress hormone. Aim 1 will use a combination of fixed and live-cell imaging, proximity proteomics, co-immunoprecipitation, and targeted mutagenesis to determine where AKAP11 resides in adrenal cells, which cellular processes and biochemical events it regulates, and its protein-protein interactions. Aim 2 will establish cardiovascular phenotypes in a previously established mouse model of stress hormone overproduction, and use a genetic approach to test whether removing adrenal AKAP11 can reduce corticosterone levels and ameliorate deleterious cardiovascular phenotypes in these mice. Together, the studies in this proposal are designed to uncover adrenal mechanisms of stress hormone production and evaluate a strategy to improve cardiovascular health in stress-induced disease.