Arachidonic acid-dependent activation of a p22(phox)-based NAD(P)H oxidase mediates angiotensin II-induced mesangial cell protein synthesis and fibronectin expression via Akt/PKB.
Angiotensin II (Ang II) induces protein synthesis and hypertrophy through arachidonic acid (AA)- and redoxdependent activation of the serine-threonine kinase Akt/PKB in mesangial cells (MCs). The role of NAD(P)H oxidase component p22( phox ) was explored in this signaling pathway and in Ang II-induced expression of the extracellular matrix protein fibronectin. Ang II causes activation of Akt/PKB and induces fibronectin protein expression, effects abrogated by phospholipase A(2) inhibition and mimicked by AA. Ang II and AAalso elicited an increase in fibronectin expression that was reduced with a dominant negative mutant of Akt/PKB. Exposure of the cells to hydrogen peroxide stimulates Akt/PKB activity and fibronectin synthesis. The antioxidant N-acetylcysteine abolished Ang II- and AA-induced Akt/PKB activation and fibronectin expression. Western blot analysis revealed high levels of p22( phox ) in MCs. Antisense (AS) but not sense oligonucleotides for p22( phox ) prevented ROS generation in response to Ang II and AA. AS p22( phox ) inhibited Ang II- or AA-induced Akt/PKB as well as protein synthesis and fibronectin expression. These data provide the first evidence, in MCs, of activation by AAof a p22( phox )-based NAD(P)H oxidase and subsequent generation of ROS. Moreover, this pathway mediates the effect of Ang II on Akt/PKB-induced protein synthesis and fibronectin expression.
Block
Karen
K
Department of Medicine, Audie L. Murphy Memorial Hospital Division, The University of Texas Health Science Center, San Antonio, 78229-3900, USA.
Ricono
Jill M
JM
Lee
Duck-Yoon
DY
Bhandari
Basant
B
Choudhury
Goutam Ghosh
GG
Abboud
Hanna E
HE
Gorin
Yves
Y
D000111:Acetylcysteine / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D050527:Mesangial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D009154:Mutation / Q000235:genetics; D019255:NADPH Oxidases / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000235:genetics; D010084:Oxidation-Reduction; D010741:Phospholipases A / Q000037:antagonists & inhibitors; D010766:Phosphorylation / Q000187:drug effects; D014176:Protein Biosynthesis / Q000187:drug effects*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
D004791:Enzyme Inhibitors; D005353:Fibronectins; D016376:Oligonucleotides, Antisense; D017382:Reactive Oxygen Species; D000804:Angiotensin II; D016718:Arachidonic Acid; D006861:Hydrogen Peroxide; D019255:NADPH Oxidases; C515768:Cyba protein, rat; D051057:Proto-Oncogene Proteins c-akt; D010741:Phospholipases A; D000111:Acetylcysteine