TLR-4 agonistic lipopolysaccharide upregulates interleukin-8 at the transcriptional and post-translational level in vascular smooth muscle cells.
Despite extensive studies on cellular responses to activation of Toll-like receptor-4 (TLR-4), it is not evident weather its activation affects gene expression of interleukin-8 (IL-8) in vascular smooth muscle cells (VSMCs). Therefore, this study has investigated whether and how TLR-4 influences IL-8 expression in VSMCs. Exposure of aortic smooth muscle cells to TLR-4 agonistic lipopolysaccharide (LPS) not only enhanced release of IL-8 protein but also induced IL-8 gene transcript via promoter activation. The LPS-induced activation of IL-8 promoter was attenuated by dominant-negative MKK1, but not by dominant-negative MKK3. The promoter activation was also impaired by dominant negative CCAAT/enhancer binding protein (C/EBP), IkappaB, and dominant negative c-Jun. In comparison with the mutation of the AP-1 binding site, the mutation of NF-kappaB site and C/EBP binding site in the IL-8 promoter region more significantly impaired the promoter activation. Moreover, both promoter activity and release of IL-8 were inhibited by U0126 and curcumin, but not by SB202190, epigallocatechin 3-gallate and resveratrol. The present study reports that TLR-4-agonistic LPS upregulates IL-8 at the transcriptional and post-translational level in VSMCs, and that ERK1/2, NF-kappaB, and C/EBP play major roles in the upregulation of IL-8.
Hong
Taek-Jong
TJ
Department of Internal Medicine, School of Medicine-Pusan National University, Busan, Republic of Korea.
Ban
Ji-Eun
JE
Choi
Kyung-Ha
KH
Son
Yong-Hae
YH
Kim
Sun-Mi
SM
Eo
Seong-Kug
SK
Park
Hee-Ju
HJ
Rhim
Byung-Yong
BY
Kim
Koanhoi
K
D001011:Aorta / Q000166:cytology / Q000378:metabolism; D022762:CCAAT-Enhancer-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D006801:Humans; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000819:agonists / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
D022762:CCAAT-Enhancer-Binding Proteins; D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D012333:RNA, Messenger; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D048051:p38 Mitogen-Activated Protein Kinases