Induction of serine and threonine protein phosphorylation by endotoxin-associated protein in murine resident peritoneal macrophages.

AUTOR(ES)

Abu-Lawi, K I

RESUMO

Endotoxin-associated protein (EP) from Salmonella typhi activated murine resident peritoneal macrophages to produce prostaglandin E2 (PGE2). Cells from both endotoxin nonresponder (C3H/HeJ) and the endotoxin responder (C3H/OuJ) mouse strains were activated by EP. This EP-induced prostaglandin E2 production was blocked by the protein kinase C (PKC) inhibitor H-7 as well as the tyrosine kinase inhibitor genistein, suggesting the involvement of both serine and threonine phosphorylation and tyrosine phosphorylation pathways in the activation of resident peritoneal macrophages by EP. Immunoblot analysis using antiphosphoserine and antiphosphothreonine antibodies showed that EP induced the serine and threonine phosphorylation of a 14-kDa protein (p14). This phosphorylation was not induced by phorbol myristic acid or by lipopolysaccharide endotoxin. Inhibitors of PKC, PKA, and PKG did not block the phosphorylation of p14. However, the tyrosine kinase inhibitor piceatannol blocked p14 serine and threonine phosphorylation, suggesting that this phosphorylation is dependent upon and preceded by a tyrosine phosphorylation step.

Documentos Relacionados

• Effects of endotoxin-associated protein on hematopoiesis.
• Roles of protein kinase C and G proteins in activation of murine resting B lymphocytes by endotoxin-associated protein.
• Stimulation of human monocytes by endotoxin-associated protein: inhibition of programmed cell death (apoptosis) and potential significance in adjuvanticity.
• Endotoxin-associated protein: interleukin-1-like activity on serum amyloid A synthesis and T-lymphocyte activation.
• Endotoxin-associated protein: a potent stimulus for human granulocytopoietic activity which may be accessory cell independent.