PKC-alpha controls MYD88-dependent TLR/IL-1R signaling and cytokine production in mouse and human dendritic cells.
Conventional PKC (cPKC)-alpha regulates TRIF-dependent IFN response factor 3 (IRF3)-mediated gene transcription, but its role in MyD88-dependent TLR signaling remains unknown. Herein, we demonstrate that PKC-alpha is induced by several MyD88-dependent TLR/IL-1R ligands and regulates cytokine expression in human and murine DC. First, inhibition of cPKC activity in human DC by cPKC-specific inhibitors, Gö6976 or HBDDe, downregulated the production of classical inflammatory/immunomodulatory cytokines induced by TLR2, TLR5 or IL-1R but not by TLR3 stimulation. Similarly, dominant negative PKC-alpha repressed Pam(3)CSK(4) induced NF-kappaB- and AP-1-driven promoter activities in TLR2-expressing human embryonic kidney 293 T cells. Dominant negative PKC-alpha inhibited NF-kappaB reporter activity mediated by overexpression of MyD88 but not TRIF. Unexpectedly, BM-derived DC from PKC-alpha(-/-) mice exhibited decreased TNF-alpha and IL-12p40 production induced by both MyD88- and TRIF-dependent ligands. Furthermore, PKC-alpha is coupled to TLR2 signaling proximal to MyD88 since MAPK and IkappaB kinase-alpha/beta phosphorylations and IkappaBalpha degradation were inhibited in PKC-alpha(-/-) BM-derived DC. Finally, co-immunoprecipitation assays revealed that PKC-alpha physically interacts with Pam(3)CSK(4) activated TLR2 in WT but not in MyD88(-/-) DC. Collectively this study identifies a species-specific role of PKC-alpha as a key component that controls MyD88-dependent cytokine gene expression in human and mouse but differentially regulates production of TRIF-dependent cytokines.
Langlet
Christelle
C
Institute for Medical Immunology, Université Libre de Bruxelles, Charleroi, Belgium.
Springael
Cécile
C
Johnson
Jolyn
J
Thomas
Séverine
S
Flamand
Véronique
V
Leitges
Michael
M
Goldman
Michel
M
Aksoy
Ezra
E
Willems
Fabienne
F
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002227:Carbazoles / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D003713:Dendritic Cells / Q000166:cytology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism*; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017472:Receptors, Interleukin-1 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism
D033942:Adaptor Proteins, Vesicular Transport; D002227:Carbazoles; D016207:Cytokines; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases; D053594:Myeloid Differentiation Factor 88; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D016328:NF-kappa B; D011493:Protein Kinase C; D017472:Receptors, Interleukin-1; D051193:Toll-Like Receptors; D018808:Transcription Factor AP-1; C476286:Ticam1 protein, mouse; C081021:Go 6976