Signal transduction pathways activated in human pulmonary endothelial cells by OxPAPC, a bioactive component of oxidized lipoproteins.
The bioactive component of mildly oxidized low-density lipoproteins, oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (OxPAPC), activates tissue factor expression and monocyte adhesion to endothelial cells (EC) from systemic circulation, but blocks expression of inflammatory adhesion molecules (VCAM, E-selectin) and neutrophil adhesion associated with EC acute inflammatory response to bacterial lypopolysacharide (LPS). Due to constant exposure to oxygen free radicals, lipids in the injured lung are especially prone to oxidative modification and increased OxPAPC generation. In this study, we focused on OxPAPC-mediated intracellular signaling mechanisms that lead to physiological responses in pulmonary endothelial cells. Our results demonstrate that OxPAPC treatment activated in a time-dependent fashion protein kinase C (PKC), protein kinase A (PKA), Raf/MEK1,2/Erk-1,2 MAP kinase cascade, JNK MAP kinase and transient protein tyrosine phosphorylation in human pulmonary artery endothelial cells (HPAEC), whereas nonoxidized PAPC was without effect. Pharmacological inhibition of PKC and tyrosine kinases blocked activation of Erk-1,2 kinase cascade upstream of Raf. OxPAPC did not affect myosin light chain (MLC) phosphorylation, but increased phosphorylation of cofillin, a molecular regulator of actin polymerization. Finally, OxPAPC induced p60Src-dependent tyrosine phosphorylation of focal adhesion proteins paxillin and FAK. Our results suggest a critical involvement of PKC and tyrosine phosphorylation in OxPAPC-induced activation of Erk-1,2 MAP kinase cascade associated with regulation of specific gene expression, and demonstrate rapid phosphorylation of cytoskeletal proteins, which indicates OxPAPC-induced EC remodeling.
Birukov
Konstantin G
KG
Division of Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA. kbirukov@jhmi.edu
Leitinger
Norbert
N
Bochkov
Valery N
VN
Garcia
Joe G N
JG
D000199:Actins / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000196:embryology; D006801:Humans; D050356:Lipid Metabolism; D008074:Lipoproteins / Q000737:chemistry*; D008168:Lung / Q000166:cytology*; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D051419:Paxillin; D010713:Phosphatidylcholines / Q000737:chemistry*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
D000199:Actins; D003598:Cytoskeletal Proteins; D008074:Lipoproteins; C496061:PXN protein, human; D051419:Paxillin; D010713:Phosphatidylcholines; D010750:Phosphoproteins; C472349:oxidized-L-alpha-1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine; D014443:Tyrosine; D016392:Proto-Oncogene Proteins pp60(c-src); D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D010100:Oxygen