Effect of increased expression of cytoskeletal protein vinculin on ischemia-reperfusion injury in ventricular myocytes

Abstract

The transition from reversible to irreversible ischemic injury (ischemia-reperfusion, I/R) occurs coincident with the loss of vinculin, a cytoskeletal protein involved in the attachment of the myofibrils to the sarcolemmal membrane. If the loss of vinculin were critical to the development of I/R, then increased levels of vinculin would be predicted to delay the onset of irreversible injury assuming that the protein is functional and localized to the proper subcellular site. The present study determined whether increased expression of vinculin, specifically in the cytoskeletal compartment, would provide protection from I/R injury. Neonatal rat myocytes were cultured and infected with a newly created replication-deficient adenovirus driving the expression of vinculin. I/R was induced with chemical inhibitors of glycolysis and mitochondrial respiration. Irreversible cell injury was assessed with lactate dehydrogenase (LDH) release. Virus-infected myocytes expressed significantly more vinculin in the cytoskeletal fraction and increased the expression of paxillin but sustained the same amount of injury in response to simulated I/R as control cells ( n = 4; P = not significant, paired t-test). Hypothermic I/R (ischemia at 25°C) resulted in a significant reduction in LDH release ( P ≤ 0.02; n = 4). Virus-mediated overexpression of vinculin does not appear to represent a rational approach to overcoming I/R injury.