CRNK Gene Transfer Improves Function and Reverses the Myosin Heavy Chain Isoform Switch During Post‐MI Remodeling

Abstract

PYK2 is a Ca2+-dependent nonreceptor tyrosine kinase that is involved in left ventricular hypertrophy (LVH) and heart failure. We and others have previously investigated PYK2's function in vitro using cultured rat ventricular myocytes. However, the function of PYK2 in the in vivo adult heart remains unknown. Here we evaluated the effect of PYK2 inhibition following myocardial infarction (MI) using adenoviral (Adv) overexpression of the C-terminal domain of PYK2, known as CRNK. CRNK functions as a dominant-negative inhibitor, presumably by displacing PYK2 from focal adhesions and costameres. Male Sprague-Dawley rats (~300g) underwent permanent left coronary artery ligation. One wk post-MI, either Adv-GFP (n=35) or Adv-CRNK (n=28) was administered (1010 pfu, 0.1ml) via catheter-based, Optison®-mediated gene transfer. LV function and infarct size were evaluated by echocardiography 1 and 3 wk after gene transfer, and LV tissue was analyzed by real-time RT-PCR and Western blotting. CRNK expression was readily detected by Western blotting 1 wk following gene transfer. Adv-CRNK improved overall survival (P=0.03; Logrank Test) and LV fractional shortening (23±2% vs. 31±2% for Adv-GFP vs. Adv-CRNK infected animals, respectively). Whereas MI hearts exhibited increased β-, and decreased α-myosin heavy chain (MHC) mRNA espression characteristic of LVH, Adv-CRNK reversed the MHC isoenzyme switch (3.3±1.4 fold increase in αMHC; 0.4±0.1 fold decrease in βMHC; P<0.05 for both). In summary, CRNK gene transfer imparts a functional benefit and alters MHC gene expression suggesting an attenuation of LV remodeling post-MI. Supported by the Dr. Ralph and Marian Falk Medical Research Trust.