Protein kinase D2 mediates lysophosphatidic acid-induced interleukin 8 production in nontransformed human colonic epithelial cells through NF-kappaB.
The signaling pathways mediating lysophosphatidic acid (LPA)-stimulated PKD(2) activation and the potential contribution of PKD(2) in regulating LPA-induced interleukin 8 (IL-8) secretion in nontransformed, human colonic epithelial NCM460 cells were examined. Treatment of serum-deprived NCM460 cells with LPA led to a rapid and striking activation of PKD(2), as measured by in vitro kinase assay and phosphorylation at the activation loop (Ser706/710) and autophosphorylation site (Ser876). PKD(2) activation induced by LPA was abrogated by preincubation with selective PKC inhibitors GF-I and Ro-31-8220 in a dose-dependent manner. These inhibitors did not have any direct inhibitory effect on PKD(2) activity. LPA induced a striking increase in IL-8 production and stimulated NF-kappaB activation, as measured by NF-kappaB-DNA binding, NF-kappaB-driven luciferase reporter activity, and IkappaBalpha phosphorylation. PKD(2) gene silencing utilizing small interfering RNAs targeting distinct PKD(2) sequences dramatically reduced LPA-stimulated NF-kappaB promoter activity and IL-8 production. PKD(2) activation is a novel early event in the biological action of LPA and mediates LPA-stimulated IL-8 secretion in NCM460 cells through a NF-kappaB-dependent pathway. Our results demonstrate, for the first time, the involvement of a member of the PKD family in the production of IL-8, a potent proinflammatory chemokine, by epithelial cells.
Chiu
Terence T
TT
Dept. of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1786, USA.
Leung
Wai Yin
WY
Moyer
Mary Pat
MP
Strieter
Robert M
RM
Rozengurt
Enrique
E
D002460:Cell Line; D003106:Colon / Q000166:cytology; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D016209:Interleukin-8 / Q000096:biosynthesis*; D007413:Intestinal Mucosa / Q000166:cytology; D008246:Lysophospholipids / Q000494:pharmacology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D000091283:Protein Kinase D2; D011494:Protein Kinases / Q000378:metabolism*
C508606:CXCL8 protein, human; D007211:Indoles; D016209:Interleukin-8; D008246:Lysophospholipids; D016328:NF-kappa B; D000091283:Protein Kinase D2; D011494:Protein Kinases; D011493:Protein Kinase C; C032881:lysophosphatidic acid; C064758:Ro 31-8220