The purpose of this Clinical Investigator Development Award is to prepare the applicant for a career as an independent investigator in cardiology. The applicant has developed a great interest in the cellular dysfunction observed in heart failure. As a Ph.D. student, the PI has closely examined the role of P-adrenergic receptor function and calcium handling in animal models of hypertrophy and heart failure as well as in single myocytes isolated from failing and non-failing human hearts. The applicant proposes to acquire additional skills in biophysics and molecular biology in the context of a project that builds on her experience on somatic gene transfer and contractile dysfunction in failing cardiac myocytes. Congestive heart failure has reached epidemic proportions in the United States. One of the key abnormalities in human heart failure is a defect in intracellular Ca2 handling associated with abnormal Ca2 reuptake into the sarcoplasmic reticulum (SR) in both human and experimental heart failure. More specifically, deficient Ca2 reuptake has been associated with a decrease in the expression and activity of SR Ca2-ATPase (SERCA2a). The applicant has shown that overexpression of exogenous SERCA2a improves contractility in failing human cardiomyocytes and survival in experimental models of heart failure. However, beyond the decrease in SERCA2a protein expression, the transporter activity was found to be decreased in failing hearts. In addition, changes in card ioprotective proteins that facilitate transport, folding of newly synthesized or refolding of damaged proteins may also occur.
The aims of this proposal are to investigate the structure function relationship of the transporter in failing hearts as well as to examine the family of cardioprotective proteins involved in folding SERCA2a. In this application, we propose to test the following hypotheses: 1) SERCA2a is structurally abnormal contributing to its deficiency in transporting Ca2 in failing hearts and 2) chaperone proteins such as Glucose Related Proteins (GRPs) GRP 78 and 94 may play an important role in the structural integration or repair of SERCA2a in normal and failing hearts. To test these hypotheses, three specific aims are proposed:
In Specific aim 1 : the crystal structure of SERCA2a will be characterized, in specific aim 2: the role of chaperone proteins will be examined through somatic gene transfer in non failing and failing human cardiomyocytes, and in specific aim 3: the role of chaperone proteins will be examined in vitro and in vivo in an animal model of heart failure.
