Surfactant protein A activation of atypical protein kinase C zeta in IkappaB-alpha-dependent anti-inflammatory immune regulation.
The pulmonary collectin surfactant protein (SP)-A has a pivotal role in anti-inflammatory modulation of lung immunity. The mechanisms underlying SP-A-mediated inhibition of LPS-induced NF-kappaB activation in vivo and in vitro are only partially understood. We previously demonstrated that SP-A stabilizes IkappaB-alpha, the primary regulator of NF-kappaB, in alveolar macrophages (AM) both constitutively and in the presence of LPS. In this study, we show that in AM and PBMC from IkappaB-alpha knockout/IkappaB-beta knockin mice, SP-A fails to inhibit LPS-induced TNF-alpha production and p65 nuclear translocation, confirming a critical role for IkappaB-alpha in SP-A-mediated LPS inhibition. We identify atypical (a) protein kinase C (PKC) zeta as a pivotal upstream regulator of SP-A-mediated IkappaB-alpha/NF-kappaB pathway modulation deduced from blocking experiments and confirmed by using AM from PKCzeta-/- mice. SP-A transiently triggers aPKCThr(410/403) phosphorylation, aPKC kinase activity, and translocation in primary rat AM. Coimmunoprecipitation experiments reveal that SP-A induces aPKC/p65 binding under constitutive conditions. Together the data indicate that anti-inflammatory macrophage activation via IkappaB-alpha by SP-A critically depends on PKCzeta activity, and thus attribute a novel, stimulus-specific signaling function to PKCzeta in SP-A-modulated pulmonary immune response.
Moulakakis
Christina
C
Department of Immunochemistry and Biochemical Microbiology, Division of Cellular Pneumology, Research Center Borstel, Leibniz Center for Medicine and Bioscience, Borstel, Germany.
Adam
Stefanie
S
Seitzer
Ulrike
U
Schromm
Andra B
AB
Leitges
Michael
M
Stamme
Cordula
C
D021581:Active Transport, Cell Nucleus; D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D004789:Enzyme Activation; D051550:I-kappa B Kinase / Q000235:genetics / Q000378:metabolism*; D007249:Inflammation / Q000188:drug therapy / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation / Q000235:genetics; D016328:NF-kappa B / Q000378:metabolism; D010769:Phosphothreonine / Q000378:metabolism; D011485:Protein Binding; D011493:Protein Kinase C / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D037662:Pulmonary Surfactant-Associated Protein A / Q000627:therapeutic use*; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D000099221:Protein Kinase C zeta
D051550:I-kappa B Kinase; D008070:Lipopolysaccharides; D016328:NF-kappa B; D010769:Phosphothreonine; D011493:Protein Kinase C; D037662:Pulmonary Surfactant-Associated Protein A; D014409:Tumor Necrosis Factor-alpha; D000099221:Protein Kinase C zeta