Desensitization of beta1 adrenergic receptor-nitric oxide signaling in cardiac diseases

Emerging evidence indicates that nitric oxide (NO) is involved in cardiac β1 adrenergic receptor (β1AR) stimulation of cardiac function. We propose that scaffold protein SAP97 plays a critical role in regulation of cardiac β1AR-induced NOS1-NO signaling cascade via organizing a β1AR- NOS1 signalosome. This pathway is necessary for regulation of cardiac contractile function. We also hypothesize that G-protein kinase 5 (GRK5) promotes phosphorylation of cardiac β1AR PDZ motif and dissociation of the receptor from the SAP97-organized signalosome for activation of NOS1-NO signaling and promotes desensitization of receptor signaling in cardiac diseases. We will test the hypotheses with the following aims. Aim 1. SAP97 regulates β1AR-induced NO signaling in heart. Aim 2. SAP97 maintains the integrity of β1AR-SAP97-NOS1 signalosome to preserve cardiac function. Aim 3. GRK5 promotes desensitization of β1AR-NO signaling via disruption of the receptor-SAP97 signalosome in heart failure.