Submitted on March 31, 2007
Accepted on August 2, 2007
Local Delivery of PKC
-Activating Peptide Mimics Ischemic Preconditioning in Aged Hearts Through GSK3
but not F1ATPase Inactivation
Donna H. Korzick1*, John C Kostyak2, James Craig Hunter2, and Kurt W. Saupe3
1 Kinesiology, The Pennsylvania State University, University Park, Pennsylvania, United States; Intercollege Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania, United States
2 Intercollege Program in Physiology, The Pennsylvania State University, University Park, Pennsylvania, United States
3 Medicine, University of Wisconsin, Madison, Madison, Wisconsin, United States
* To whom correspondence should be addressed. E-mail: dhk102{at}psu.edu.
In adult heart, selective PKC
activation limits ischemia/reperfusion (I/R) damage and mimics the protection associated with ischemic preconditioning. We sought to determine whether local delivery of an PKC-activator peptide (
RACK) is sufficient to produce a similarly protected phenotype in aged hearts. Langendorff-perfused hearts isolated from adult (5 mo; n=9) and aged (24 mo; n=9) male Fisher 344 rats were perfused with either RACK conjugated to Tat (500 nM) or Tat-only (500 nM) for 10 min prior to global 31 min ischemia. Western blotting was used to measure mitochondrial targeting of PKC, PKC
, p-GSK-3
(ser9) and GSK-3 in hearts snap frozen during I. Recovery of LV developed pressure was significantly improved by RACK (p<0.01) and infarct size reduced in 24 mo vs age-matched controls (60% vs 34%; p<0.01). Mitochondrial PKC levels were 30% greater during I with RACK in aged vs controls (p<0.01). Interestingly, mitochondrial GSK-3 levels were 3-fold greater in aged vs adult during I, and RACK prevented this increase. Mitochondrial p-GSK-3 levels were also greater in aged following RACK (p<0.01), and subsequent inhibition of GSK-3 with SB 216763 (3 µM) prior to I/R elicited protection similar to that observed for RACK (n=3/group). Mitochondrial proteomic analysis further identified group differences in the F1-ATPase- subunit, and coimmunoprecipitation studies revealed a novel interaction with PKC. F1-ATPase-PKC association was affected by ψεRACK in adult but not aged. Our results provide evidence, for the first time, for PKC-mediated protection in aged rat heart following I/R. Our results also suggest a central role for mitochondrial GSK-3 but not the F1ATPase as a potential target of PKC to limit I/R damage with aging.
