Differential involvement of PKC-dependent MAPKs activation in lipopolysaccharide-induced AP-1 expression in human tracheal smooth muscle cells.
Lipopolysaccharide (LPS) has been shown to up-regulate the expression of vascular cell adhesion molecule (VCAM)-1 which contributes to the occurrence of airway inflammatory diseases. Genetic analysis reveals the existence of activator protein-1 (AP-1) binding site on VCAM-1 promoter region. However, the role of AP-1 in LPS-induced VCAM-1 expression in human tracheal smooth muscle cells (HTSMCs) is not known. Here, we show that LPS increased VCAM-1 expression and adhesiveness of HTSMCs through AP-1, since pretreatment with an AP-1 inhibitor tanshinone attenuated LPS-induced VCAM-1 expression and leukocytes adhesion. The implication of AP-1 in LPS-induced VCAM-1 expression was confirmed by animal studies showing that pretreatment of mice with tanshinone attenuated LPS-induced VCAM-1 mRNA expression in airway tissues and accumulation of leukocytes in bronchoalveolar lavage. By using the pharmacological inhibitors and transfection with siRNA of PKC, p42, p38, or JNK2, LPS-induced expression of c-Fos was mediated through protein kinase C (PKC), p42/p44 MAPK and p38 MAPK. While, c-Jun expression was mediated through PKC and mitogen-activated protein kinases (MAPKs, p42/p44 MAPK, p38 MAPK and JNK) in HTSMCs. Pretreatment with the inhibitors of PKCs or MAPKs attenuated LPS-stimulated nuclear translocation and VCAM-1 promoter binding abilities of AP-1, which attenuated promoter activity and gene expression of VCAM-1 and the adhesiveness between HTSMCs and leukocytes. These results indicated that differential regulation of AP-1 through PKCs-dependent MAPKs activation plays central roles in LPS-induced VCAM-1 expression. The altered modulation of this axis with inhibitors or siRNAs may contribute to the improvement of airway inflammatory diseases.
Lin
Wei-Ning
WN
Department of Physiology and Pharmacology, Chang Gung University and Chang Gung Memorial Hospital, Tao-Yuan, Taiwan.
Luo
Shue-Fen
SF
Lin
Chih-Chung
CC
Hsiao
Li-Der
LD
Yang
Chuen-Mao
CM
D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000201:enzymology / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction; D014132:Trachea / Q000166:cytology; D018808:Transcription Factor AP-1 / Q000378:metabolism* / Q000502:physiology; D019010:Vascular Cell Adhesion Molecule-1 / Q000378:metabolism*
D008070:Lipopolysaccharides; D034741:RNA, Small Interfering; D018808:Transcription Factor AP-1; D019010:Vascular Cell Adhesion Molecule-1; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases