title: Simvastatin modulates angiotensin II signaling pathway by preventing Rac1-mediated upregulation of p27.
abstract: Recent experimental observations have suggested that statins may exert modulatory effects on a number of pathobiological processes beyond their cholesterol-lowering properties. Some of the pleiotropic effects of statins seem to be mediated by their ability to block the synthesis of isoprenoid intermediates, which serve as important lipid attachments required for the proper function and activation of the small GTP-binding proteins. The current study explored the modulatory effects of simvastatin (SMV) on the angiotensin II (Ang II)-induced Rac1-mediated, upregulation of cyclin-dependent kinase inhibitor p27. Ang II (100 nM) stimulation of rat mesangial cells induced a significant increase in p27 protein expression. Co-treatment of cells with SMV (1 microM) inhibited Ang II-induced upregulation of p27 protein. Addition of mevalonate (200 microM) or geranylgeranyl pyrophosphate (5 microM) reversed the inhibitory effect of SMV on p27 protein expression, suggesting that the effect of SMV is geranylgeranyl dependent. This study also provides evidence for a sequential link between Ang II stimulation and downstream activation of Rac1, intracellular H2O2 production, and Akt kinase leading to upregulation of p27 protein in mesangial cells. It was also shown that SMV, by inhibiting Rac1 activity, reversed Ang II-induced increase in intracellular H2O2 production, Akt activation, and p27 protein expression. The data presented in this study not only elucidate Ang II-mediated signaling cascade in mesangial cells but also demonstrate for the first time the modulatory effects of SMV on Ang II-induced signaling pathway at the cell cycle level.
authors.affiliation: Division of Nephrology/Hypertension, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: Lixia
authors.initials: L
authors.lastname: Zeng
authors.forename: Hanshi
authors.initials: H
authors.lastname: Xu
authors.forename: Teng-Leong
authors.initials: TL
authors.lastname: Chew
authors.forename: Rex
authors.initials: R
authors.lastname: Chisholm
authors.forename: Mehran M
authors.initials: MM
authors.lastname: Sadeghi
authors.forename: Yashpal S
authors.initials: YS
authors.lastname: Kanwar
authors.forename: Farhad R
authors.initials: FR
authors.lastname: Danesh
mesh_terms: D021581:Active Transport, Cell Nucleus; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D002460:Cell Line; D050760:Cyclin-Dependent Kinase Inhibitor p27; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D007930:Leucine / Q000378:metabolism; D018613:Microscopy, Confocal; D008954:Models, Biological; D010084:Oxidation-Reduction; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D015398:Signal Transduction; D019821:Simvastatin / Q000494:pharmacology*; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000096:biosynthesis*; D015854:Up-Regulation; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: C493962:Cdkn1b protein, rat; D018797:Cell Cycle Proteins; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011518:Proto-Oncogene Proteins; D025521:Tumor Suppressor Proteins; D000804:Angiotensin II; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019821:Simvastatin; D006861:Hydrogen Peroxide; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020830:rac1 GTP-Binding Protein; D007930:Leucine