Redox-dependent dimerization of p38alpha mitogen-activated protein kinase with mitogen-activated protein kinase kinase 3 [Protein Structure and Folding]

The kinase p38α-MAPK (p38α) plays a pivotal role in many biological processes. p38α is activated by canonical upstream kinases that phosphorylate the activation region. The purpose of our study was to determine if such activation may dependent on redox-sensing cysteines within p38α. p38α was activated and formed a disulfide-bound heterodimer with MAP2K3 (MKK3) in rat cardiomyocytes and isolated hearts exposed to H2O2. This disulfide heterodimer was sensitive to reduction by mercaptoethanol and was enhanced by the thioredoxin-reductase inhibitor auranofin. We predicted that Cys119 or Cys162 of p38α, close to the known MKK3 docking domain, were relevant for these redox characteristics. C119S mutation decreased while C162S mutation increased the dimer formation, suggesting that these two Cys residues act as vicinal thiols, consistent with C119S/C162S being incapable of sensing H2O2. Similarly, disulfide heterodimer formation was abolished in H9C2 cells expressing both MKK3 and p38αC119S/C162S and subjected to simulated ischemia and reperfusion. However, the p38αC119S/C162S mutants did not exhibit appreciable alteration in activating dual phosphorylation. In contrast, the anti-inflammatory agent 10-nitro-oleic acid (NO2-OA), a component of the Mediterranean diet, reduced p38α activation and covalently modified Cys119/Cys162, likely obstructing MKK3 access. Moreover, NO2-OA reduced the dephosphorylation of p38α by the phosphatase HePTP. Furthermore, steric obstruction of Cys119/Cys162 by NO2-OA pretreatment in Langendorff-perfused murine hearts prevented the p38-MKK3 disulfide dimer formation and attenuated H2O2 -induced contractile dysfunction. Our findings suggest that cysteine residues within p38α act as redox sensors that can dynamically regulate the association between p38 and MKK3.

from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/2vDwZPS
via IFTTT