Mitogen-activated protein kinase activation by hydrogen peroxide is mediated through tyrosine kinase-dependent, protein kinase C-independent pathways in vascular smooth muscle cells: upregulation in spontaneously hypertensive rats.
OBJECTIVE
To investigate the putative molecular mechanisms underlying mitogen-activated protein (MAP) kinase activation by hydrogen peroxide (H(2)O(2)) in vascular smooth muscle cells (VSMC) and to evaluate whether H(2)O(2)-induced actions are altered in VSMC from spontaneously hypertensive rats (SHR).


METHODS
VSMC from mesenteric arteries of Wistar-Kyoto rats (WKY) and SHR were stimulated with H(2)O(2) (2-30 min). The phosphorylation of extracellular signal-regulated kinases (ERK)1/2 and p38MAP kinase was determined by immunoblotting. The involvement of tyrosine kinase and protein kinase C (PKC) was evaluated using pharmacological inhibitors, tyrphostin (A23 and A9) and GF109203X, respectively. The role of receptor tyrosine kinases (RTK) was assessed with AG1478, AG1296 and AG1024, selective inhibitors of epidermal growth factor receptor, platelet-derived growth factor receptor and insulin-like growth factor receptor, respectively. Non-receptor tyrosine kinases (NRTK) were studied using AG490 (JAK2 inhibitor) and PP2 (Src inhibitor).


RESULTS
H(2)O(2) stimulated phosphorylation of ERK1/2 and p38MAP kinase in a time-dependent manner. This increase was significantly greater in SHR versus WKY (P < 0.01). The activation of MAP kinases was unaffected by GF109203X but was decreased by tyrphostins (P < 0.01). The inhibition of NRTK attenuated H(2)O(2)-mediated phosphorylation of ERK1/2 (P < 0.001) but not of p38MAP kinase, whereas Src and JAK2 inhibition significantly decreased phosphorylation of both MAP kinases (P < 0.01).


CONCLUSIONS
These data indicate that H(2)O(2) increases ERK1/2 and p38MAP kinase activation through tyrosine kinase-dependent, PKC-independent mechanisms. Whereas ERK1/2 is regulated by both RTK and NRTK, p38MAP kinase is regulated by NRTK. Our findings identify an important role for tyrosine kinases, but not PKC, in H(2)O(2)-induced phosphorylation of ERK1/2 and p38MAP kinase in VSMC. The upregulation of these processes may contribute to enhanced redox-dependent MAP kinase signaling in SHR VSMC.
Tabet
Fatiha
F
Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montreal, University of Montreal, Quebec, Canada.
Schiffrin
Ernesto L
EL
Touyz
Rhian M
RM
D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D066246:ErbB Receptors / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D053614:Janus Kinase 2; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism; D017451:Receptors, Somatomedin / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
D016877:Oxidants; D011518:Proto-Oncogene Proteins; D017451:Receptors, Somatomedin; D006861:Hydrogen Peroxide; D011494:Protein Kinases; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; C507927:Jak2 protein, rat; D053614:Janus Kinase 2; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases