PKCε modulates NF-κB and AP-1 via mitogen-activated protein kinases in adult rabbit cardiomyocytes

Abstract

We have previously shown that protein kinase C (PKC)-epsilon, nuclear factor (NF)-kappaB, and mitogen-activated protein kinases (MAPKs) are essential signaling elements in ischemic preconditioning. In the present study, we examined whether activation of PKCepsilon affects the activation of NF-kappaB in cardiac myocytes and whether MAPKs are mediators of this signaling event. Activation of PKCepsilon (+108% above control) in adult rabbit cardiomyocytes to a degree that has been previously shown to protect myocytes against hypoxic injury increased the DNA-binding activity of NF-kappaB (+164%) and activator protein (AP)-1 (+127%) but not that of Elk-1. Activation of PKCeta did not have an effect on these transcription factors. Activation of PKCepsilon also enhanced the phosphorylation activities of the p44/p42 MAPKs and the p54/p46 c-Jun NH(2)-terminal kinases (JNKs). PKCepsilon-induced activation of NF-kappaB and AP-1 was completely abolished by inhibition of the p44/p42 MAPK pathway with PD98059 and by inhibition of the p54/p46 JNK pathway with a dominant negative mutant of MAPK kinase-4, indicating that both signaling pathways are necessary. Taken together, these data identify NF-kappaB and AP-1 as downstream targets of PKCepsilon, thereby establishing a molecular link between activation of PKCepsilon and activation of NF-kappaB and AP-1 in cardiomyocytes. The results further demonstrate that both the p44/p42 MAPK and the p54/p46 JNK signaling pathways are essential mediators of this event.

Protein kinase Cϵ interacts with cytochrome c oxidase subunit IV and enhances cytochrome c oxidase activity in neonatal cardiac myocyte preconditioning

“…ETC uncoupling does not appear to be required for this protection, as agonists that activate AMPK without mitochondria uncoupling produce the same effects [72]. Furthermore, these treatments also activate p38 MAPK [73], which (in the absence of irreversible mitochondrial uncoupling) also produces cardioprotection [19][20][21]. AMPK also inhibits acetyl-CoA carboxylase and HMG-CoA reductase (3-hydroxy-3-methylglutaryl-CoA reductase), which will increase fatty acid oxidation in heart and also lower cholesterol levels.…”

“…It is well known that the PKCε isoenzyme induces cardioprotection during cardiac PC [2, 19,20,24,28,29,31,[33][34][35][36][37]49]. Many mitochondrial signalling events have been proposed to contribute to this protection including the formation of signalling modules between PKCε and MAPKs [19], inhibition of the MPTP [33] and elevation of mitochondrial ROS [77,78].…”

“…Experimentally, it is the most powerful form of cardiac protection known and it has been demonstrated in cardiac myocytes [2][3][4][5], intact hearts [6,7] and many animal species [8][9][10][11], including humans [12][13][14]. Downstream signalling molecules reported to be involved in PC include ATPdependent potassium channels [4,12,15,16], PKC (protein kinase C) isoenzymes [2, 3,12,15,17,18], MAPK (mitogen-activated protein kinase) enzymes [19][20][21], tyrosine kinases [22][23][24], PI3K (phosphoinositide 3-kinase) [22,25], heat-shock proteins [5,16,26], nitric oxide [27][28][29], free radicals [21,25,30] etc.…”

“…Evidence has also emerged that one downstream mechanism of PKCε-mediated PC involves activation of the tyrosine kinases src and lck [23,24]. PKCε-induced PC also appears to involve enhanced activities of MAPKs, JNKs (c-Jun N-terminal kinases) and NF-κB (nuclear factor κB) and AP-1 (activator protein-1) transcription factors [20]. PC has been reported to involve the formation of signalling complexes between PKCε and ERKs (extracellular-signal-regulated kinases) inside cardiac mitochondria to promote the phosphorylation and inhibition of the apoptotic protein Bad [19].…”

Expression of constitutively stable hybrid hypoxia-inducible factor-1α protects cultured rat cardiomyocytes against simulated ischemia-reperfusion injury

“…Myocardial protein synthesis of several mediators (or effectors), including inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), aldose reductase, antioxidant enzymes, and heat shock proteins (HSPs), and activation of ATP-sensitive K ϩ (K ATP ) channels play a critical role in late-phase preconditioning (8,15,21,23,24,29). It has been proposed that activator protein 1 (AP-1) and nuclear factor-B (NF-B) may mediate the transcriptional activation of iNOS, COX-2, aldose reductase, and other genes (22,36).…”