title: AMP-dependent kinase inhibits oxidative stress-induced caveolin-1 phosphorylation and endocytosis by suppressing the dissociation between c-Abl and Prdx1 proteins in endothelial cells.
abstract: Caveolin-1 is the primary structural component of endothelial caveolae that is essential for transcellular trafficking of albumin and is also a critical scaffolding protein that regulates the activity of signaling molecules in caveolae. Phosphorylation of caveolin-1 plays a fundamental role in the mechanism of oxidant-induced vascular hyper permeability. However, the regulatory mechanism of caveolin-1 phosphorylation remains unclear. Here we identify a previously unexpected role for AMPK in inhibition of caveolin-1 phosphorylation under oxidative stress. A pharmacological activator of AMPK, 5-amino-4-imidazole carboxamide riboside (AICAR), inhibited oxidative stress-induced phosphorylation of both caveolin-1 and c-Abl, which is the major kinase of caveolin-1, and endocytosis of albumin in human umbilical vein endothelial cell. These effects were abolished by treatment with two specific inhibitors of AICAR, dipyridamole, and 5-iodotubericidin. Consistently, knockdown of the catalytic AMPKα subunit by siRNA abolished the inhibitory effect of AICAR on oxidant-induced phosphorylation of both caveolin-1 and c-Abl. Pretreatment with specific c-Abl inhibitor, imatinib mesylate, and knock down of c-Abl significantly decreased the caveolin-1 phosphorylation after H2O2 exposure and abolished the inhibitory effect of AICAR on the caveolin-1 phosphorylation. Interestingly, knockdown of Prdx-1, an antioxidant enzyme associated with c-Abl, increased phosphorylation of both caveolin-1 and c-Abl and abolished the inhibitory effect of AICAR on the caveolin-1 phosphorylation. Furthermore, co-immunoprecipitation experiment showed that AICAR suppressed the oxidant-induced dissociation between c-Abl and Prdx1. Overall, our results suggest that activation of AMPK inhibits oxidative stress-induced caveolin-1 phosphorylation and endocytosis, and this effect is mediated in part by stabilizing the interaction between c-Abl and Prdx-1.
authors.affiliation: Retina Service, Angiogenesis Laboratory, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA.
authors.forename: Kimio
authors.initials: K
authors.lastname: Takeuchi
authors.forename: Yuki
authors.initials: Y
authors.lastname: Morizane
authors.forename: Cynthia
authors.initials: C
authors.lastname: Kamami-Levy
authors.forename: Jun
authors.initials: J
authors.lastname: Suzuki
authors.forename: Maki
authors.initials: M
authors.lastname: Kayama
authors.forename: Wenyi
authors.initials: W
authors.lastname: Cai
authors.forename: Joan W
authors.initials: JW
authors.lastname: Miller
authors.forename: Demetrios G
authors.initials: DG
authors.lastname: Vavvas
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000418:Albumins / Q000378:metabolism / Q000493:pharmacokinetics; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D015153:Blotting, Western; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D004176:Dipyridamole / Q000494:pharmacology; D004705:Endocytosis; D004789:Enzyme Activation / Q000187:drug effects; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress; D054464:Peroxiredoxins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding; D016315:Proto-Oncogene Proteins c-abl / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012265:Ribonucleotides / Q000494:pharmacology; D014372:Tubercidin / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D000418:Albumins; D051242:Caveolin 1; D007527:Isoenzymes; D016877:Oxidants; D012265:Ribonucleotides; C034214:5-iodotubercidin; D000620:Aminoimidazole Carboxamide; D004176:Dipyridamole; D006861:Hydrogen Peroxide; C515940:PRDX1 protein, human; D054464:Peroxiredoxins; D016315:Proto-Oncogene Proteins c-abl; D055372:AMP-Activated Protein Kinases; C031143:AICA ribonucleotide; D014372:Tubercidin
keywords: AMP-activated kinase (AMPK); Caveolae; Caveolin; Endocytosis; Oxidative Stress