Abstract 12734: Characterisation of mapk14/mapk11 Mediated Cardioprotection Using Rnai
Previous cell and animal studies focusing on the p38-MAPK pathway have shown cardioprotection can be enhanced via modulation of the p38-MAPK pathway, however to date the specific subtypes that are activated or inhibited remain elusive. The objective of this study was to indirectly characterise the p38-MAPK pathway by silencing MAPK14 and MAPK11, the dominant p38-MAPK subtypes expressed in the heart, using RNAi. Preliminary studies were conducted using HL-1 cardiomyocytes that were transiently transfected with either MAPK14 or MAPK11 miRNA expressing vectors or a GFP expressing vector as a control. Following transfection cells were subjected to 2 hours ischaemia then 6 hours reperfusion after which LDH release and transcriptional changes were determined. Silencing of MAPK14 resulted in a 17% reduction in LDH release. Transcriptional changes resulting from MAPK14 silencing include significant increases in MAP2K6 and GSK3B expression and significant decreases in myc expression. Silencing of MAPK11 resulted in a 31% reduction in LDH. Transcriptional changes resulting from MAPK11 silencing include significant increases in MAP2K6 and GSK3B expression and significant decreases in MAP2K3, MAPK14, EGR1 and myc expression. Collectively this data shows that while loss of MAPK14 expression provides reasonable protection against reperfusion injury, as quantified via LDH release, loss of MAPK11 expression virtually reduced LDH release back to baseline levels, almost preventing reperfusion injury. By observing the transcripts expressed and suppressed it is possible to deduce that to effectively prevent reperfusion injury it is necessary to suppress MAP2K3, MAPK11, MAPK14, EGR1 and myc expression. In conclusion these results support the hypothesis that inhibition of p38-MAPK not activation is cardioprotective, which is mediated by suppression of the nuclear transcriptional response and enhanced activation of the mitochondria.
- © 2013 by American Heart Association, Inc.