title: Downregulation of catalase by reactive oxygen species via PI 3 kinase/Akt signaling in mesangial cells.
abstract: Reactive oxygen species (ROS) contribute to many glomerular diseases by targeting mesangial cells. ROS have been shown to regulate expression of many antioxidant enzymes including catalase. The mechanism by which the expression of catalase protein is regulated by ROS is not precisely known. Here we report that increased intracellular ROS level by hydrogen peroxide (H(2)O(2)) reduced the expression of catalase. H(2)O(2) increased phosphorylation of Akt kinase in a dose-dependent and sustained manner with a concomitant increase in the phosphorylation of FoxO1 transcription factor. Further analysis revealed that H(2)O(2) promoted rapid activation of phosphatidylinositol (PI) 3 kinase. The PI 3 kinase inhibitor Ly294002 and expression of tumor suppressor protein PTEN inhibited Akt kinase activity, resulting in the attenuation of FoxO1 phosphorylation and preventing the downregulating effect of H(2)O(2) on catalase protein level. Dominant negative Akt attenuated the inhibitory effect of H(2)O(2) on expression of catalase. Constitutively active FoxO1 increased the expression of catalase. However, dominant negative FoxO1 inhibited catalase protein level. Catalase transcription was reduced by H(2)O(2) treatment. Furthermore, expression of dominant negative Akt and constitutively active FoxO1 increased catalase transcription, respectively. These results demonstrate that ROS downregulate the expression of catalase in mesangial cells by PI 3 kinase/Akt signaling via FoxO1 as a target.
authors.affiliation: Department of Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA.
authors.forename: Balachandar
authors.initials: B
authors.lastname: Venkatesan
authors.forename: Lenin
authors.initials: L
authors.lastname: Mahimainathan
authors.forename: Falguni
authors.initials: F
authors.lastname: Das
authors.forename: Nandini
authors.initials: N
authors.lastname: Ghosh-Choudhury
authors.forename: Goutam
authors.initials: G
authors.lastname: Ghosh Choudhury
mesh_terms: D000818:Animals; D002374:Catalase / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000494:pharmacology; D050527:Mesangial Cells / Q000201:enzymology*; D009025:Morpholines / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D016877:Oxidants / Q000494:pharmacology; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D000071161:Forkhead Box Protein O1
chemical_list: D002374:Catalase; D002867:Chromones; D004791:Enzyme Inhibitors; D051858:Forkhead Transcription Factors; D006861:Hydrogen Peroxide; D009025:Morpholines; D009419:Nerve Tissue Proteins; D016877:Oxidants; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D017382:Reactive Oxygen Species; C074639:Foxo1 protein, rat; D000071161:Forkhead Box Protein O1; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one