Regulation of Adenylyl Cyclase Signaling Pathways

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Summary Adenylyl cyclase (AC) and its product, cyclic AMP, regulate functional outcomes in every mammalian tissue and organ system, controlling processes such as learning and memory, motor coordination, cardiac contractility, drug dependency and withdrawal, renal function, pain, stress, immune responses, and anxiety behavior, to name just a few. Importantly, G protein coupled receptors that transmit signals via stimulation (Gαs) or inhibition (Gαi) of AC are major clinical drug targets (e.g. beta-blockers for heart disease, opioids for pain, or beta-agonists for asthma). Funded largely by NIGMS, my research career over the last 27 years has focused on how the catalytic activity of AC enzymes are regulated by G proteins and other regulatory molecules. Additionally, we are interested in how AC/cAMP signaling specificity can occur in a cellular environment. We have identified multiple macromolecular complexes assembled by A-kinase anchoring proteins that respond to low levels of local cAMP production upon anchoring of AC to the system, driving physiological responses, or when altered, have pathophysiological consequences. However, many fundamental questions remain about the mechanisms of AC regulation within these signalosomes, the regulation of ACs by covalent modifications, and the potential for regulation of cellular events from intracellular sites. To address these key questions, we have performed proximity dependent identification of near neighbors (BioID) to build a comprehensive AC interaction network in cardiomyocytes and characterized new tools for selectively probing the properties of AC9. These will be applied to broad projects that examine the scaffolding of AC activity that ultimately control cardiac pacemaking and conduction. Popdc proteins act as one novel scaffold for AC enzymes that promote AC activity within the complex to drive cAMP-dependent regulation of TREK channels. The unique mechanism of AC regulation by Popdc and the localization of this complex will be further explored in two related projects. Additionally, we will examine the mechanism of AC regulation by a novel modifying enzyme, identified by BioID. Although these modes of regulating cAMP signaling will be examined in the context of cardiomyocytes and cardiac function, many of the mechanisms are universal in nature and have implications for many biological systems.