Cytotoxic role of methylglyoxal in rat retinal pericytes: Involvement of a nuclear factor-kappaB and inducible nitric oxide synthase pathway.
Methylglyoxal (MGO), a cytotoxic metabolite, is produced from glycolysis. Elevated levels of MGO are observed in a number of diabetic complications, including retinopathy, nephropathy and cardiomyopathy. Loss of retinal pericyte, a hallmark of early diabetic retinal changes, leads to the development of formation of microaneurysms, retinal hemorrhages and neovasculization. Herein, we evaluated the cytotoxic role of MGO in retinal pericytes and further investigated the signaling pathway leading to cell death. Rat primary retinal pericytes were exposed to 400muM MGO for 6h. Retinal vessels were prepared from intravitreally MGO-injected rat eyes. We demonstrated apoptosis, nuclear factor-kappaB (NF-kappaB) activation and inducible nitric oxide synthase (iNOS) induction in cultured pericytes treated with MGO and MGO-injected retinal vessels. In MGO-treated pericytes, TUNEL-positive nuclei were markedly increased, and NF-kappaB was translocalized into the nuclei of pericytes, which paralleled the expression of iNOS. The treatment of pyrrolidine dithiocarbamate (an NF-kappaB inhibitor) or l-N6-(1-iminoethyl)-lysine (an iNOS inhibitor) prevented apoptosis of MGO-treated pericytes. In addition, in intravitreally MGO-injected rat eyes, TUNEL and caspase-3-positive pericytes were significantly increased, and activated NF-kappaB and iNOS were highly expressed. These results suggest that the increased expression of NF-kappaB and iNOS caused by MGO is involved in rat retinal pericyte apoptosis.
Kim
Junghyun
J
Diabetic Complications Research Center, Division of Traditional Korean Medicine (TKM) Integrated Research, Korea Institute of Oriental Medicine (KIOM), 483 Exporo, Yuseong-gu, Daejeon 305-811, South Korea.
Kim
Ohn Soon
OS
Kim
Chan-Sik
CS
Kim
Nan Hee
NH
Kim
Jin Sook
JS
D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D020287:In Situ Nick-End Labeling; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism*; D020286:Pericytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D011765:Pyruvaldehyde / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism
D016328:NF-kappa B; D011765:Pyruvaldehyde; D052247:Nitric Oxide Synthase Type II