Identification of a NF-κB cardioprotective gene program: NF-κB regulation of Hsp70.1 contributes to cardioprotection after permanent coronary occlusion

The transcription factor Nuclear Factor Kappa B (NF-kappa B) has been shown to be cardioprotective after permanent coronary occlusion (PO) and late ischemic preconditioning (IPC), and yet it is cell injurious after ischemia/reperfusion (I/R) in the heart. There is limited information regarding NF-kappa B-dependent cardioprotection, and the NF-kappa B-dependent genes that contribute to the cardioprotection after PO are completely unknown. The objective of the study was to identify NF-kappa B-dependent genes that contribute to cardioprotection after PO. Microarray analysis was used to delineate genes that potentially contribute to the NF-kappa B-dependent cardioprotection by determining the overlap between the set of PO regulated genes and genes regulated by NF-kappa B, using mice with genetic abrogation of NF-kappa B activation in the heart. This analysis identified 16 genes as candidates for NF-kappa B-dependent effects after PO. This set of genes overlaps with, but is significantly different from the set of genes we previously identified as regulated by NF-kappa B after IPC. The genes encoding heat shock protein 70.3 (hspa1a) and heat shock protein 70.1 (hspa1b) were the most significantly regulated genes after PO and were up-regulated by NF-kappa B. Results using knockout mice show that Hsp70.1 contributes to NF-kappa B-dependent cardioprotection after PO and likely underlies, at least in part, the NF-kappa B-dependent cardioprotective effect. Our previous results show that Hsp70.1 is injurious after I/R injury. This demonstrates that, like NF-kappa B itself, Hsp70.1 has antithetical effects on myocardial survival and suggests that this may underlie the similar antithetical effects of NF-kappa B after different ischemic stimuli. The significance of the research is that understanding the gene network regulated by NF-kappa B after ischemic insult may lead to identification of therapeutic targets more appropriate for clinical development. (C) 2011 Elsevier Ltd. All rights reserved.