Src tyrosine kinases mediate crystalline silica-induced NF-kappaB activation through tyrosine phosphorylation of IkappaB-alpha and p65 NF-kappaB in RAW 264.7 macrophages.
Protein tyrosine kinases (PTKs) and mitogen-activated protein kinases (MAPKs) have been demonstrated to play a crucial role in the signaling pathways induced by silica. In the present study, we investigated whether Src family TKs play a role in crystalline silica-induced NF-kappaB activation and whether NF-kappaB activation requires Src TK-dependent MAPK activity in RAW 264.7 cells, a mouse peritoneal macrophage cell line. Selective Src TK inhibitors, damnacanthal or PP1, inhibited silica-induced NF-kappaB activation in a dose-dependent manner. Furthermore, these kinase inhibitors suppressed silica-induced tyrosine phosphorylation of IkappaB-alpha and p65 NF-kappaB. Within a similar time frame, c-Src and Lck were physically associated with IkappaB-alpha and with p65 NF-kappaB. Silica stimulated the phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), but not p38 MAPK and c-Jun NH(2)-terminal kinase 1 and 2 (JNK1/2). Damnacanthal or PP1 substantially blocked the silica-induced activation of ERK1/2. Moreover, PD98059, an inhibitor of ERK1/2, or SB203580, an inhibitor of p38 MAPK, failed to inhibit silica-induced NF-kappaB activation. These results suggest that c-Src and Lck act for silica-induced NF-kappaB activation by mediating the tyrosine phosphorylations of IkappaB-alpha and p65 NF-kappaB. However, the Src TK-dependent activation of ERK1/2 may not be involved in the silica signaling pathway leading to NF-kappaB activation.
Kang
Jihee Lee
JL
Department of Physiology, Division of Cell Biology, Ewha Medical Research Center, Ewha Womans University College of Medicine, Seoul, Korea. jihee@ewha.ac.kr
Jung
Hae J
HJ
Lee
Kyungeun
K
Kim
Hyung R
HR
D000818:Animals; D000880:Anthraquinones / Q000494:pharmacology; D000081247:CSK Tyrosine-Protein Kinase; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020672:I-kappa B Proteins / Q000378:metabolism; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D012822:Silicon Dioxide / Q000633:toxicity*; D051996:Transcription Factor RelA / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases
C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D000880:Anthraquinones; D004791:Enzyme Inhibitors; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D011720:Pyrazoles; D011743:Pyrimidines; C498144:Rela protein, mouse; D051996:Transcription Factor RelA; D000072000:NF-KappaB Inhibitor alpha; D014443:Tyrosine; C079170:damnacanthal; D012822:Silicon Dioxide; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D019061:src-Family Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3