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.
Department of Physiology and Pharmacology, Chang Gung University and Chang Gung Memorial Hospital, Tao-Yuan, Taiwan.
Wei-Ning
WN
Lin
Shue-Fen
SF
Luo
Chih-Chung
CC
Lin
Li-Der
LD
Hsiao
Chuen-Mao
CM
Yang
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