title: Involvement of CaM kinase II in the impairment of endothelial function and eNOS activity in aortas of Type 2 diabetic rats.
abstract: In the present sutdy, we have examined the relationship between the CaMKII (Ca(2+)/calmodulin-dependent protein kinase II) pathway and endothelial dysfunction in aortas from GK (Goto-Kakizaki) Type 2 diabetic rats. The ACh (acetylcholine)-induced relaxation and NO production were each attenuated in diabetic aortas (compared with those from age-matched control rats). ACh-stimulated Ser(1177)-eNOS (endothelial NO synthase) phosphorylation was significantly decreased in diabetic aortas (compared with their controls). ACh markedly increased the CaMKII phosphorylation level within endothelial cells only in control aortas (as assessed by immunohistochemistry and Western blotting). ACh-stimulated Thr(286)-CaMKII phosphorylation within endothelial cells was significantly decreased in diabetic aortas (compared with their controls). The ACh-induced relaxations, NO production, eNOS phosphorylation, and CaMKII phosphorylation were inhibited by KN93 and/or by lavendustin C (inhibitors of CaMKII) in control aortas, but not in diabetic ones. Pre-incubation of aortic strips with a PP (protein phosphatase)-1 inhibitor, PPI2 (protein phosphatase inhibitor 2), or with a PP2A inhibitor, CA (cantharidic acid), corrected the above abnormalities in diabetic aortas. The expression of PP2A type A subunit was increased in diabetic aortas. The ACh-stimulated Thr(320)-phosphorylation level of PP1α was lower in diabetic aortas than in their controls, but the total PP1α protein level was not different. These results suggest that the aortic relaxation responses, NO production, and eNOS activity mediated by CaMKII phosphorylation are decreased in this Type 2 diabetic model, and that these impairments of CaMKII signalling may be, at least in part, due to enhancements of PP1α activity and PP2A expression.
authors.affiliation: Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan. tkoba@hoshi.ac.jp
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Shingo
authors.initials: S
authors.lastname: Nemoto
authors.forename: Keiko
authors.initials: K
authors.lastname: Ishida
authors.forename: Kumiko
authors.initials: K
authors.lastname: Taguchi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Katsuo
authors.initials: K
authors.lastname: Kamata
mesh_terms: D000109:Acetylcholine / Q000378:metabolism / Q000502:physiology; D000818:Animals; D001011:Aorta / Q000201:enzymology*; D001596:Benzylamines / Q000494:pharmacology; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000037:antagonists & inhibitors / Q000502:physiology*; D003924:Diabetes Mellitus, Type 2 / Q000201:enzymology* / Q000503:physiopathology; D066298:In Vitro Techniques; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D054645:Protein Phosphatase 1 / Q000378:metabolism; D054648:Protein Phosphatase 2 / Q000378:metabolism; D011506:Proteins / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology; D000097847:Protein Phosphatase Inhibitory Proteins; D000096926:Benzenesulfonamides
chemical_list: D000109:Acetylcholine; D001596:Benzylamines; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D010636:Phenols; D010749:Phosphoprotein Phosphatases; D047428:Protein Kinase Inhibitors; D054645:Protein Phosphatase 1; D054648:Protein Phosphatase 2; D011506:Proteins; D013449:Sulfonamides; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins; C072105:KN 93; D000096926:Benzenesulfonamides; C080022:lavendustin C6; C496316:Nos3 protein, rat