Activation of protein kinase CK2 by LPS is mediated by the MAP kinase pathway

Abstract

Stimulation of macrophages by Gram-negative bacterial lipopolysaccharide (LPS) rapidly leads to the activation of several protein kinases and the subsequent phosphorylation of transcription factors that regulate LPS-inducible genes. Several investigators have shown that the MAP kinases (MAPKs) are rapidly activated following LPS stimulation. We previously reported that LPS stimulation also up-regulates the enzymatic activity of protein kinase CK2, a ubiquitous serine/threonine kinase, although the signaling cascade that leads to CK2 activation in macrophages is unknown. Because MAPKs are known to be rapidly activated by LPS, we performed additional studies in order to determine if CK2 activation was a downstream target of MAPKs. Our studies revealed that CK2 activity was rapidly and transiently up-regulated in LPS-stimulated RAW264.7 murine macrophages. We found that PD98059, an inhibitor of ERK kinase activation by the MAP kinase MEK-1, blocked LPS-induced up-regulation of CK2 activity. In contrast, the p38 kinase inhibitor SB203580 did not block CK2 activation by LPS. This finding suggests that CK2 activation was mediated by the ERK kinase signaling cascade, but not by the p38 kinase cascade. We also found that LPS stimulation resulted in the rapid serine phosphorylation of the catalytic α and α′ subunits of CK2. This contrasts with other studies using growth factor-stimulated fibroblasts in which only phosphorylation of the regulatory β subunit of CK2 was observed. Thus, LPS stimulation leads to rapid activation and cell type-specific phosphorylation of CK2 in macrophages.

References

Sweet MJ , Hume DA Endotoxin signal transduction in macrophages. J Leukoc Biol 1996; 60: 8—26.

Beaty C. , Franklin T. , Uehara Y. , Wilson C. Lipopolysaccharide-induced cytokine production in human monocytes: role oftyrosine phosphorylation in transmembrane signal transduction. Eur J Immunol 1994; 26: 1278—1284.

Weinstein S. , Gold M. , DeFranco A. Bacterial lipopolysaccharide stimulates protein tyrosine kinase phosphorylation in macrophages. Proc Natl Acad Sci USA 1991; 88: 4148—4152.

Dong Z. , O'Brian C. , Fidler I. Activation of tumoricidal properties in macrophages by lipopolysaccharide and interferon gamma is mediated by tyrosine-protein kinase activity. J Leukoc Biol 1993; 53: 53—59.

Pinna L. Protein kinase CK2. Int J Biochem Cell Biol 1997; 29: 551—554.

Lodie TA , Savedra R. , Golenbock DT , Van Beveren CP , Maki RA , Fenton MJ Stimulation of macrophages by lipopolysaccharide alters the phosphorylation state, conformation, and function of PU.1 via activation of casein kinase II. J Immunol 1997; 158: 1848—1856.

Meisner H. , Czech M. Phosphorylation of transcriptional factors and cell-cycle-dependent proteins by casein kinase II. Curr Opin Cell Biol 1991 ; 3: 474—483.

Xu X. , Rich EJ , Seldin D. Murine protein kinase CK2 alpha': cDNA and genomic cloning and chromosomal mapping. Genomics 1998; 48: 79—86.

Seldin DC , Leder P. Casein kinase IIα transgene-induced murine lymphoma: relation to theileriosis in cattle. Science 1995; 267: 894—897.

10.

Ackerman P. , Glover Cvc , Osheroff N. Stimulation of casein kinase II by EGF: relationship between the physiological activity of the kinase and the phosphorylation state of its beta subunit. Proc Natl Acad Sci USA 1990; 87: 821—825.

11.

Kim S. , Kahn C. Insulin regulation of mitogen-activated protein kinase kinase (MEK), mitogen-activated protein kinase and casein kinase in the cell nucleus: a possible role in the regulation of gene expression. Biochem J 1997 ; 323: 621—627.

12.

Hambleton J. , Weinstein SL , Lem L. , DeFranco AL Activation of c-Jun N-terminal kinase in bacterial lipopolysaccharide-stimulated macrophages. Proc Natl Acad Sci USA 1996; 93: 2774—2778.

13.

Litchfield DW , Luscher B. Casein kinase II in signal transduction and cell cycle regulation. Mol Cell Biochem 1993 ; 127: 187—199.

14.

Penner C. , Wang Z. , Litchfield DW Expression and localization of epitope-tagged protein kinase CK2. J Cell Biochem 1997; 64: 525—537.

15.

Pongubala Jmr , Van Beveren C , Nagulapalli S. et al. Effect of PU.1 phosphorylation on interaction with NFEM5 and transcriptional activation. Science 1993; 259: 1662—1665.

16.

Pongubala JM , Nagulapalli S. , Klemsz MJ , McKercher SR , Maki RA , Atchison ML PU.1 recruits a second nuclear factor to a site important for immunoglobulin κ 3′ enhancer activity. Mol Cell Biol 1992; 12: 368—378.