title: Downregulation of Rac1 activation by caffeic acid in aortic smooth muscle cells.
abstract: Caffeic acid, a dietary phenol from coffee, fruits and vegetables, is an efficient antioxidant. However, little is known about its anti-oxidative mechanism in the modulation of fundamental cellular processes. In this study, we investigated whether caffeic acid regulates Rac1 GTPase activity, a partner of NADPH oxidase. Our results showed that caffeic acid decrease Rac1 protein level under basal conditions and incubation with angiotensin II (ANG II) in vascular smooth muscle cells. In a Rac-bound-to-PAK pull down assay, caffeic acid clearly inhibited Rac1 activity. We also observed that caffeic acid suppressed the generation of superoxide anion stimulated by ANG II that activates NADPH oxidase. On the other hand, co-incubation with caffei caid and cycloheximide significantly accelerated the Rac1 degradation. In addition, pretreatment with caffeic acid for 24 hours was able to prevent phosphorylation of MLC and HSP27, when cells were challenged with ANG II through the redox sensitive pathway. These results support the hypothesis that caffeic acid reduces Rac1 GTPase protein and activity level, followed by a down-regulation of NADPH oxidase activity.
authors.affiliation: Frontier Health Science, School of Human Environmental Science, MUKOGAWA Women's University, Nishinomiya, Hyogo, 663-8179, Japan. jwxu@mwu.mukogawa-u.ac.jp
authors.forename: Jin-Wen
authors.initials: JW
authors.lastname: Xu
authors.forename: Katsumi
authors.initials: K
authors.lastname: Ikeda
authors.forename: Akira
authors.initials: A
authors.lastname: Kobayakawa
authors.forename: Takao
authors.initials: T
authors.lastname: Ikami
authors.forename: Yasuyo
authors.initials: Y
authors.lastname: Kayano
authors.forename: Takahiko
authors.initials: T
authors.lastname: Mitani
authors.forename: Yukio
authors.initials: Y
authors.lastname: Yamori
mesh_terms: D000704:Analysis of Variance; D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001011:Aorta / Q000166:cytology*; D015153:Blotting, Western; D002109:Caffeic Acids / Q000494:pharmacology*; D003513:Cycloheximide / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D051381:Rats; D011921:Rats, Inbred WKY; D013481:Superoxides / Q000378:metabolism; D014162:Transfection; D054462:p21-Activated Kinases; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D002109:Caffeic Acids; D055551:HSP27 Heat-Shock Proteins; D006360:Heat-Shock Proteins; C486114:Hspb1 protein, rat; D009363:Neoplasm Proteins; D013481:Superoxides; D000804:Angiotensin II; D003513:Cycloheximide; C515906:Pak1 protein, rat; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; C499134:Rac1 protein, rat; D020830:rac1 GTP-Binding Protein; C040048:caffeic acid