Activation of the p38 and p42/p44 families by the histamine H-1 receptor mitogen-activated protein kinase in DDT1MF-2 cells

1 The mitogen-activated protein kinases (MAPKs) consist of the p42/p44 MAPK S and the stress-activated protein kinases. c-Jun N-terminal kinase (JNK) a nd p38 MAPK. In this study we have examined the effect of histamine H-1 rec eptor activation on MAPK pathway activation in the smooth muscle cell line DDT1MF-2. 2 Histamine stimulated time and concentration-dependent increases in p42/p4 4 MAPK activation in DDT1MF-2 cells. Responses to histamine were inhibited by the histamine H-1 receptor antagonist mepyramine (K-D 3.5 nM) and follow ing pre-treatment with pertussis toxin (PTX; 57% inhibition). 3 Histamine-induced increases in p42/p44 MAPK activation were blocked by in hibitors of MAPK kinase 1 (PD 98059), tyrosine kinase (genistein and tyrpho stin A47), phosphatidylinositol 3-kinase (wortmannin and LY 294002) and pro tein kinase C (Ro 31-8220; 10 muM, 41% inhibition). Inhibitors of Sre tyros ine kinase (PP2) and the epidermal growth factor tyrosine kinase (AG1479) w ere without effect. Removal of extracellular Ca2+, chelation of intracellul ar Ca2+ with BAPTA and inhibition of focal adhesion assembly (cytochalasin D) had no significant effect on histamine-induced p42/p44 MAPK activation. 4 Histamine stimulated time and concentration-dependent increases in p38 MA PK activation in DDT1MF-2 cells but had no effect on JNK activation. Histam ine-induced p38 MAPK activation was inhibited by pertussis toxin (74% inhib ition) and the p38 MAPK inhibitor SB 203580 (95% inhibition). 5 In summary. we have shown the histamine H-1 receptor activates p42/p44 MA PK and p38 MAPK signalling pathways in DDT1MF-2 smooth muscle cells. Intere stingly, signalling to both pathways appears to involve histamine H-1 recep tor coupling to G(i)/G(o)-proteins.