RNA interference targeting SHP-1 attenuates myocardial infarction in rats

The Src homology domain 2 (SH2)-containing tyrosine phosphatase-1 (SHP-1) plays a key role in apoptosis and decreases phosphorylation of Akt. Apoptosis of cardiomyocytes is thought to contribute to the increased area of acute myocardial infarction (AMI), and Akt activation exerts a powerful cardioprotective effect after ischemia. Thus, a therapeutic strategy designed to inhibit expression of SHP-1 would be beneficial in AMI. Here we report that siRNA targeting SHP-1 reduced infarct size in a rat model of AMI. Upon injection into the ischemic left ventricular wall, the vector-based siRNA significantly suppressed the increase in the SHP-1 mRNA and the SHP-1 protein levels. The siRNA vector also significantly reduced the SHP-1 that bound to Fas-R. The SHP-1 siRNA vector increased phospho-Akt and reduced DNA fragmentation and caspase activity compared with the scramble siRNA vector. Finally, the area of myocardial infarction was significantly smaller with the SHP-1 siRNA vector than with the scramble siRNA vector at 2 days after LCA ligation. In conclusion, SHP-1 in the heart increased from the early stage of AMI, and this increase was thought to contribute to the increased area of myocardial infarction. Suppression of SHP-1 with the SHP-1 siRNA vector markedly reduced the infarct size in AMI.