Protein phosphorylation pathways involved during lipopolysaccharide-induced expression of CD14 in mouse bone marrow granulocytes

Lipopolysaccharide (LPS) of Gram-negative bacteria interacts with a CD14-in dependent receptor of mouse bone marrow granulocytes (BMC), and triggers in these cells the expression of CD14, an inducible type of LPS receptor (iLp sR). This particular response of BMC to LPS required the activation of prot ein tyrosine kinase and p38 MAP kinase. The inhibition of the LPS effect by the MEK inhibitor PD-98059 suggested that the ERE: pathway was also involv ed. Unexpectedly, protein kinase C, myosin light chain kinase, cAMP-, cGMP- , and Ca2+/calmodulin-dependent kinases, as well as ecto-protein kinases, w ere not required for iLpsR expression. However, other yet unidentified seri ne/threonine protein kinase(s) were implied since the BMC response to LPS w as markedly reduced after exposure to three inhibitors of such kinases (K-2 52a, H-7, and KT-5823). The atypical kinase requirements observed in this s tudy may be due either to a novel signaling LPS receptor complex present in BMC, or to the particular events involved in CD14 biosynthesis. (C) 2000 F ederation of European Microbiological Societies. Published by Elsevier Scie nce B.V. All rights reserved.