For the past 10 years my scientific career has been devoted to translational cardiovascular research. My doctoral studies investigated the role of the voltage-gated potassium channel Kv1.5 as a potential therapeutic target atrial fibrillation. These studies had a strong cell biology focus, determining the mechanisms underlying channel trafficking and regulation and how these were altered by pharmaceutical intervention. A goal in joining the Koch lab for my postdoctoral studies was to broaden my understanding of cardiovascular disease progression within the context of in vivo studies, with a greater focus on therapeutic interventions for human heart failure (HF). Preliminary data generated for the current proposal shows that both the amino(N)-terminal RGS (Regulator of G-protein Signaling) domain of GRK2 (aa 45-185, ?ARKrgs) and a shorter N-terminal peptide of GRK2 (aa 45-185, ?ARKnt) can alter cardiac physiology when expressed in myocytes. Of note, these two peptides both appear to halt HF progression in mice after pressure-overload but have differential effects on the initial hypertrophic response. The K99 portion of this proposal will focus on whether ?ARKrgs and ?ARKnt can act therapeutically to reverse left-ventricular (LV) remodeling after cardiac injury. These studies will begin with an evaluation of the in vivo efficacy of ?ARKrgs or ?ARKnt gene-therapy to reverse adaptive hypertrophy acutely or restore function during chronic pressure overload. In addition, I will continue to practice the murine myocardial infarction (MI) model under the guidance of Dr. Erhe Gao. During the R00 phase of this proposal I will use the cardiac-restricted transgenic ?ARKrgs and ?ARKnt mice and my newly- developed gene therapy vectors to determine whether these peptides prevent adverse remodeling post-MI. During the K99 phase I will also use proteomic approaches to identify specific binding partners for ?ARKrgs and ?ARKnt in vivo, compared to full-length GRK2, and whether these binding interactions are altered after cardiac injury or upon agonist stimulation. For these studies I will work closely with Dr. Salim Merali, Director of the Proteomics Research Facility at Temple, to gain invaluable insight and training in the proper execution and evaluation of proteomic analysis. In these studies ?ARKrgs and ?ARKnt will serve as powerful tools to dissect the specific domains within the N-terminus of GRK2 responsible for protein interactions and the role they play in the regulation of cardiovascular cell signaling. Novel protein interactions discovered in this project will provide new avenues for independent research. A focus of the R00 phase will be to narrow down and pursue the protein binding partners that represent key elements of cardiac signaling or potential therapeutic targets for improving cardiac structure and function in disease. Support through the NIH Pathway to Independent K99/R00 award would provide the necessary time and resources for achieving these important research goals, and continuing my personal development toward my overall goal of obtaining a tenure-track faculty position.
Heart disease is the leading cause of death in Americans, resulting from co-morbid conditions including chronic hypertension and heart attack that culminate in the development of heart failure (HF). While significant advances have been made in stabilizing and relieving symptoms of HF patients, the underlying mechanisms of cardiac remodeling are still a major focus of research efforts towards therapeutic development. This proposal will investigate whether the N-terminal peptides of GRK2, ?ARKrgs and ?ARKnt, can act therapeutically to reverse cardiac remodeling after injury, and will use these peptides as tools to determine whether select activities can be assigned to specific domains within GRK2, including distinct protein-proteins interactions and regulation that will expand our understanding of cardiovascular signaling pathways and may highlight new therapeutic targets for the treatment of human HF.