Signaling pathways involved in the physiological response of mussel hemocytes to bacterial challenge: the role of stress-activated p38 MAP kinases.
In this work the mechanisms of transduction triggered in Mytilus galloprovincialis hemocytes by bacterial challenge were investigated in an in vitro model of infection of hemocyte monolayers with Escherichia coli. Western blot analyses of hemocyte extracts with phospho-specific anti-MAPK (Mitogen Activated Protein Kinase) antibodies indicate that E. coli induced a time dependent activation of different classes of MAPKs, mainly of the stress-activated p38 MAPK. P38 activation was confirmed by the use of the selective kinase inhibitor SB203580. Moreover, hemocyte pretreatment with SB203580 significantly reduced bacterial killing, whereas PD98059, an inhibitor of extracellularly regulated kinase (ERK) activation, was ineffective. Interestingly, the PI3-kinase (phosphatidylinositol-3-OH-kinase) inhibitor, Wortmannin, reduced both p38 activation and bacterial killing, indicating a critical role also for this lipid kinase in the hemocyte immune response.
Canesi
Laura
L
Istituto di Scienze Fisiologiche, Università di Urbino, Loc. Crocicchia, 61029 (PU), Urbino, Italy. canesi@uniurb.it
Betti
Michele
M
Ciacci
Caterina
C
Scarpato
Alfonso
A
Citterio
Barbara
B
Pruzzo
Carla
C
Gallo
Gabriella
G
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D049872:Bivalvia / Q000166:cytology / Q000201:enzymology* / Q000276:immunology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000276:immunology / Q000472:pathogenicity; D005419:Flavonoids / Q000494:pharmacology; D006434:Hemocytes / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology*; D007093:Imidazoles / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines / Q000494:pharmacology; D015398:Signal Transduction; D000077191:Wortmannin; D048051:p38 Mitogen-Activated Protein Kinases
D000730:Androstadienes; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D000077191:Wortmannin