SR Ca2+‐handling proteins and PKC: a role in low molecular weight FGF2‐mediated cardioprotection

Abstract

Fibroblast growth factor 2 (FGF2) protects against cardiac dysfunction caused by ischemia‐reperfusion (I/R). Our lab has shown that mouse models overexpressing all FGF2 isoforms or expressing only the low molecular weight (LMW) isoform (high molecular weight knockout, HMWKO) improved cardiac function following I/R, while ablation of FGF2 (FGFKO) decreased function. Protein kinase C (PKC), a modulator of Ca2+ homeostasis via phosphorylation of sarcoplasmic reticulum (SR) proteins, contributes to FGF2‐induced cardioprotection; yet the role of PKC and SR proteins in LMW FGF2‐mediated cardioprotection is unknown. Here, expression and phosphorylation of multiple SR proteins, including phospholamban (PLB), were measured in non‐ischemic WT, FGFKO, and HMWKO hearts to determine if these proteins may prime against cardiac I/R injury. Also, WT, FGFKO and HMWKO hearts underwent an ex vivo work‐performing heart model of I/R, and phospho‐Thr17 PLB was measured in the absence or presence of a PKCε inhibitor, to elucidate what role phospho‐PLB and PKCε may play in LMW FGF2‐induced protection against cardiac dysfunction. Significant changes in phosphorylation of SR proteins in HMWKO hearts prior to and during I/R suggest that Ca2+ handling proteins may play a role in LMW FGF2‐induced protection against myocardial dysfunction and that these changes may be mediated by PKC. Work supported by NIH T35 DK 60444 and HL075633.