Cardioprotective 3′,4′-dihydroxyflavonol attenuation of JNK and p38MAPK signalling involves CaMKII inhibition

Abstract

DiOHF (3',4'-dihydroxyflavonol) is cardioprotective against I/R (ischaemia/reperfusion) injury. The biological activities of flavonols are associated with kinase modulation to alter cell signalling. We thus investigated the effects of DiOHF on the activation of MAPKs (mitogen-activated protein kinases) that regulate the cardiac stress response. In an ovine model of I/R, JNK (c-Jun N-terminal kinase), p38(MAPK), ERK (extracellular-signal-regulated kinase) and Akt were activated, and NP202, a pro-drug of DiOHF, reduced infarct size and inhibited JNK and p38(MAPK) activation, whereas ERK and Akt phosphorylation were unaltered. Similarly, in cultured myoblasts, DiOHF pre-treatment preserved viability and inhibited activation of JNK and p38(MAPK), but not ERK in response to acute oxidative and chemotoxic stress. Furthermore, DiOHF prevented stress-activation of the direct upstream regulators MKK4/7 (MAPK kinase 4/7) and MKK3/6 respectively. We utilized small-molecule affinity purification and identified CaMKII (Ca(2+)/calmodulin-dependent protein kinase II) as a kinase targeted by DiOHF and demonstrated potent CaMKII inhibition by DiOHF in vitro. Moreover, the specific inhibition of CaMKII with KN-93, but not KN-92, prevented oxidative stress-induced activation of JNK and p38(MAPK). The present study indicates DiOHF inhibition of CaMKII and attenuation of MKK3/6→p38(MAPK) and MKK4/7→JNK signalling as a requirement for the protective effects of DiOHF against stress stimuli and myocardial I/R injury.

Complement‐induced activation of MAPKs and Akt during sepsis: role in cardiac dysfunction

“…We found coinvolvement of MAPK and Akt signaling in I/R injury in liver (20). Several other reports showed involvement of both MAPK and Akt signaling pathways in cardiac I/R injury (21)(22)(23)(24)(25)(26). To our knowledge, there are few, if any, published reports about the coinvolvement of MAPKs and Akt signaling pathways in cardiac defects after sepsis.…”

Flavonols in the Prevention of Diabetes-induced Vascular Dysfunction

“…In a sheep model of myocardial ischemia/reperfusion, DiOHF attenuated p38MAPK and JNK phosphorylation with no effects on ERK and Akt phosphorylation. 74 These findings 74 are consistent with observations in cardiomyocytes under oxidative and chemical stress, where DiOHF inhibited the JNK and p38MAPK pathways. Furthermore, DiOHF prevented stress-induced activation of the direct upstream regulators MKK4/7 (MAPK kinase 4/7) and MKK3/6.…”

ESC Working Group Cellular Biology of the Heart: Position Paper: improving the preclinical assessment of novel cardioprotective therapies

“…The simulated acute I/R injury model itself can vary, with the use of a variety of different insults to simulate acute I/R injury including metabolic inhibition (using cyanide), 31 hypoxic pelleting of cells (using surface mineral oil), 32 , 33 and oxidative stress (using hydrogen peroxide). 34 However, these experimental models are unable to recapitulate the complex conditions of acute I/R injury.…”

“…Genetic divergence between different inbred mouse strains leads to variations in ex vivo and in vivo cardiac function 82 and also infarct size. 34 These physiological differences, and also different responses to the environment and stress from one strain of mice to another strain of mice, may explain variations in MI sizes when mice are subjected to the exactly same protocol of I/R. 34 , 83 …”

“… 34 These physiological differences, and also different responses to the environment and stress from one strain of mice to another strain of mice, may explain variations in MI sizes when mice are subjected to the exactly same protocol of I/R. 34 , 83 …”