Date of Award

8-2019

Degree Type

Thesis

Degree Name

Master of Science in Biomedical Sciences

First Advisor

Lindon Young, PhD

Second Advisor

Robert Barsotti, PhD

Third Advisor

Cathy Hatcher, PhD

Abstract

Protein kinase C epsilon (PKCε) activation is a central mediator of the cardioprotection conferred by myocardial ischemic preconditioning (IPC). PKCε activation via PKCε peptide activator (PKCε+, HDAPIGYD) prior to ischemia is a pharmacologic mimic of IPC. However, native PKCε+ requires the use of cell permeabilization methods, such as conjugation to known carrier peptides, for effective intracellular targeting to mitigate cardiac damage. Our study compares PKCε+ conjugated to either myristic acid (Myr- PKCε+) or transactivating (TAT) carrier peptide (YGRKKRRQRRR-CC- PKCε+) with native PKCε+ pretreatment and untreated control I/R hearts to evaluate the efficacy of these cell permeable peptide analogs in attenuating contractile dysfunction and infarct size after MI (30min)/R (90min). Infarct size was assessed by 1% triphenyltetrazolium chloride staining of heart tissue, which was evaluated using NIH ImageJ software pixel analysis and weight dissection analysis. ImageJ pixel analysis showed significantly reduced infarct size in the Myr-PKCε+ (29±1%, p<0.05) and TAT-PKCε+ (25±2%, p<0.01) pretreated hearts compared to native PKCε+ pretreated (34±2%) and control I/R hearts (35±2%). By contrast, only TAT-PKCε+ pretreated hearts (26±2%, p<0.01) exhibited significant difference from native PKCε+ pretreated hearts (35±2%) and control hearts (36±2%) when evaluated via weight dissection. Despite significant improvement in infarct size, there was no significant improvement in post-perfused cardiac function across all groups. These results indicate that PKCε+ conjugation to either Myr or TAT significantly improved its efficaciousness in attenuating infarct size when given before ischemia. Further, this improvement was independent of cardiac function. These results suggest that Myr- or TAT-conjugated PKCε+ may be an effective treatment to attenuate cell death in coronary bypass or organ transplantation settings.

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