Phospholipase C (PLC) enzymes hydrolyze phosphatidylinositols (PIs) to produce diacylglycerol (DAG) and inositol polyphosphates (IP), which activate protein kinase C (PKC) and promote intracellular calcium release, respectively. These second messengers are critical for many physiological processes, and within the cardiovascular system they regulate cell growth and survival. PLCepsilon has emerged as a key player in cardiovascular health, where its activity regulates contractility and hypertrophic gene expression. PLCepsilon is activated downstream of G protein coupled receptors, including the beta-adrenergic receptors, through direct interactions with small G proteins. The best characterized PLCepsilon activator is the small G protein Rap1A. Rap1∙GTP binds to PLCepsilon and translocates the activated complex to the perinuclear membrane, where phosphatidylinositol-4-phosphate (PI4P) is hydrolyzed, activating PKC and downstream kinases that culminate the upregulation of genes that promote cardiac hypertrophy. However, while Rap1A is known to interact with the C-terminal Ras association (RA) domain of PLCepsilon, the molecular basis of activation is unknown. I propose to characterize the interactions between Rap1A and PLCepsilon using structural and functional studies and determine whether activation involves conformational changes that relieve autoinhibition and/or increase membrane association. These studies will provide the first molecular details of the Rap1A-dependent activation of PLCepsilon.
|Program type||Predoctoral Fellowship|
|Effective start/end date||07/01/2018 → 08/03/2019|