Ca2+/Calmodulin-dependent protein kinase II ? mediates myocardial ischemia/reperfusion injury through nuclear factor-?B.

ABSTRACT: Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) has been implicated as a maladaptive mediator of cardiac ischemic injury. We hypothesized that the inflammatory response associated with in vivo ischemia/reperfusion (I/R) is initiated through CaMKII signaling.To assess the contribution of CaMKII? to the development of inflammation, infarct, and ventricular dysfunction after in vivo I/R and define early cardiomyocyte-autonomous events regulated by CaMKII? using cardiac-specific knockout mice.Wild-type and CaMKII? knockout mice were subjected to in vivo I/R by occlusion of the left anterior descending artery for 1 hour followed by reperfusion for various times. CaMKII? deletion protected the heart against I/R damage as evidenced by decreased infarct size, attenuated apoptosis, and improved functional recovery. CaMKII? deletion also attenuated I/R-induced inflammation and upregulation of nuclear factor-?B (NF-?B) target genes. Further studies demonstrated that I/R rapidly increases CaMKII activity, leading to NF-?B activation within minutes of reperfusion. Experiments using cyclosporine A and cardiac-specific CaMKII? knockout mice indicate that NF-?B activation is initiated independent of necrosis and within cardiomyocytes. Expression of activated CaMKII in cardiomyocytes leads to I?B kinase phosphorylation and concomitant increases in nuclear p65. Experiments using an I?B kinase inhibitor support the conclusion that this is a proximal site of CaMKII-mediated NF-?B activation.This is the first study demonstrating that CaMKII? mediates NF-?B activation in cardiomyocytes after in vivo I/R and suggests that CaMKII? serves to trigger, as well as to sustain subsequent changes in inflammatory gene expression that contribute to myocardial I/R damage.

SUBMITTER: Ling H 

PROVIDER: S-EPMC3673710 | biostudies-other | 2013 Mar

REPOSITORIES: biostudies-other