Phosphoinositide 3-kinase mediates CD40 ligand-induced oxidative stress and endothelial dysfunction via Rac1 and NADPH oxidase 2.
OBJECTIVE
CD40 ligand (CD40L) has been implicated as an inducer of reactive oxygen species (ROS) generation in endothelial cells, but definitive evidence for this and the in vivo relevance haves not been demonstrated fully. We thus investigated whether phosphoinositide 3-kinase (PI3K) was linked to ROS generation and endothelial reactivity in response to CD40L.


RESULTS
CD40L treatment activated PI3K activity by regulating the association between PI3K p85 and the CD40 receptor. CD40L exposure also stimulated the GTPase Rac1, which is known to activate NADPH oxidases, and enhanced ROS formation, whereas PI3K inhibition or depletion by small interfering RNA (siRNA) prevented these responses. Subsequently, PI3K overexpression activated Rac1 and increased ROS generation. These responses were not observed in the presence of inactive Rac1 or siRNA against the NADPH oxidase subunit NOX2. Protein kinase Czeta mediates PI3K-regulated NADPH oxidase activation by promoting cellular p47phox translocation. Importantly, PI3K inhibition prevented CD40L-mediated ROS generation and endothelial dysfunction in a mouse model. In summary, PI3K mediates CD40L-induced ROS production and subsequent endothelial dysfunction.


CONCLUSIONS
Targeting PI3K may provide a new therapeutic approach in diseases associated with oxidative stress and endothelial dysfunction.
Xia
M
M
Department of Nutrition, School of Public Health, Sun Yat-Sen University, Guangzhou, China. xiamin@mail.sysu.edu.cn
Li
G
G
Ma
J
J
Ling
W
W
D000818:Animals; D019013:CD40 Antigens / Q000378:metabolism; D023201:CD40 Ligand / Q000008:administration & dosage / Q000378:metabolism*; D002478:Cells, Cultured; D002867:Chromones / Q000008:administration & dosage; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D004789:Enzyme Activation; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009025:Morpholines / Q000008:administration & dosage; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D021381:Protein Transport; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014664:Vasodilation; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*; D000099221:Protein Kinase C zeta
D019013:CD40 Antigens; D023201:CD40 Ligand; D002867:Chromones; D008562:Membrane Glycoproteins; D009025:Morpholines; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C; D047428:Protein Kinase Inhibitors; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; D020830:rac1 GTP-Binding Protein; D000099221:Protein Kinase C zeta; C107953:RAC1 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C056558:CYBB protein, human; C060505:neutrophil cytosolic factor 1