title: Cyclic stretch-induced reactive oxygen species generation enhances apoptosis in retinal pericytes through c-jun NH2-terminal kinase activation.
abstract: Hypertension is known to exacerbate diabetic complications, such as retinopathy and nephropathy. Apoptosis of retinal vascular pericytes has been well established as the earliest conceivable change in diabetic retinopathy. In this study, we investigated the contribution of cyclic stretch, which mimics a hypertensive state to pericyte apoptosis. A 48-hour cyclic stretch induced DNA fragmentation in porcine retinal pericytes and increased the number of TUNEL+ cells at a pathophysiologically relevant extension level (10%/60 cycles per minute). Stretch also increased intracellular reactive oxygen species generation and increased c-Jun NH(2)-terminal kinase phosphorylation in a time- and magnitude-dependent manner, which were reduced by the nicotinamide-adenine dinucleotide phosphate oxidase inhibitor diphenylene iodonium or dominant-negative protein kinase C-delta. Stretch activated protein kinase C-delta and increased its association with p47phox. Stretch induced cleavage of caspase-9 and -3 and increased caspase-3 activity. Protein kinase C-delta or c-Jun NH(2)-terminal kinase inhibition normalized stretch-induced caspase-3 activity and prevented stretch-induced apoptosis. These data indicate that cyclic stretch induces apoptosis in porcine retinal pericytes by activation of the reactive oxygen species-c-Jun NH(2)-terminal kinase-caspase cascades, suggesting a novel molecular mechanism to explain the exacerbation of early diabetic retinopathy by concomitant hypertension.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kawara-cho 54, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Suzuma
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Murakami
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Suzuma
authors.forename: Hideaki
authors.initials: H
authors.lastname: Kaneto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Watanabe
authors.forename: Tomonari
authors.initials: T
authors.lastname: Ojima
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Honda
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Takagi
authors.forename: Nagahisa
authors.initials: N
authors.lastname: Yoshimura
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism; D020286:Pericytes / Q000502:physiology*; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000502:physiology*; D013314:Stress, Mechanical; D013552:Swine; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; D051745:Protein Kinase C-delta; D048031:JNK Mitogen-Activated Protein Kinases; D020169:Caspases