Arreola-Mendoza Laura, Del Razo Luz M, Mendoza-Garrido Maria E, Martin Dolores, Namorado Maria C, Calderon-Salinas Jose V, Reyes Jose L
Toxicology Dept, Centre for Research and Advanced Studies, National Polytechnic Institute (Cinvestav-IPN), Av. Instituto Politécnico Nacional #2508, Col. San Pedro Zacatenco, México DF, 07360, Mexico.
Toxicol Lett. 2009 Dec 15;191(2-3):279-88. doi: 10.1016/j.toxlet.2009.09.011. Epub 2009 Sep 17.
Renal tight junctions (TJ) play a central role in modulating the paracellular pathway. We examined the function, quantity and distribution of TJ proteins: occludin and claudin-2 (cln-2), on proximal tubule in a model of acute renal failure (ARF) associated with oxidative damage. Since ERK1/2-p modulates TJ integrity, we studied their participation in dichromate (Cr(6+)) toxicity. We evaluated whether co-administration of the antioxidant alpha-tocopherol (alpha-TOC) prevents Cr(6+) toxicity in TJ. Female Wistar rats received potassium dichromate 15 mg/kg, s.c. (5.3 mg/kg of Cr(6+)) single dose, with or without alpha-TOC (125 mg/kg, p.o., daily). Two and 7 days after Cr(6+) treatment, oxidative damage was assessed by renal lipid peroxidation (LPO), proximal function was estimated by sodium and glucose fractional excretions. Occludin, cln-2, and ERK1/2-p were detected by immunofluorescence and Western blot. ARF induced by Cr(6+) provoked augment in the sodium and glucose urinary looses, increases in occludin quantity (6.6- and 15-fold on days 2 and 7, respectively) and the mislocation of cln-2. Electrophoresis migration showed a higher molecular weight band only in the Cr(6+)-administered groups, suggesting occludin hyperphosphorylation. Alpha-TOC treatment diminished the LPO, improved tubular function, and preserved TJ location and expression. In summary, we show disruption of occludin and cln-2 in ARF induced by Cr(6+)-intoxication. This study provides evidence of the beneficial effect of alpha-TOC on TJ structure and function undergoing oxidative damage, and we suggest the participation of ERK1/2 in the mechanisms leading to protection by the antioxidant.
肾紧密连接（TJ）在调节细胞旁途径中起核心作用。我们在与氧化损伤相关的急性肾衰竭（ARF）模型中，研究了TJ蛋白（闭合蛋白和紧密连接蛋白-2（cln-2））在近端小管中的功能、数量和分布。由于细胞外信号调节激酶1/2磷酸化（ERK1/2-p）调节TJ完整性，我们研究了它们在重铬酸盐（Cr(6+)）毒性中的作用。我们评估了抗氧化剂α-生育酚（α-TOC）联合给药是否能预防Cr(6+)对TJ的毒性。雌性Wistar大鼠皮下注射15 mg/kg重铬酸钾（5.3 mg/kg的Cr(6+)）单剂量，伴或不伴α-TOC（125 mg/kg，口服，每日）。Cr(6+)处理后2天和7天，通过肾脂质过氧化（LPO）评估氧化损伤，通过钠和葡萄糖分数排泄估计近端功能。通过免疫荧光和蛋白质印迹检测闭合蛋白、cln-2和ERK1/2-p。Cr(6+)诱导的ARF导致钠和葡萄糖尿排泄增加，闭合蛋白数量增加（第2天和第7天分别增加6.6倍和15倍）以及cln-2错位。电泳迁移显示仅在给予Cr(6+)的组中出现更高分子量条带，提示闭合蛋白过度磷酸化。α-TOC处理减少了LPO，改善了肾小管功能，并保留了TJ的定位和表达。总之，我们显示Cr(6+)中毒诱导的ARF中闭合蛋白和cln-2的破坏。本研究提供了α-TOC对遭受氧化损伤的TJ结构和功能有益作用的证据，并且我们提示ERK1/2参与抗氧化剂导致保护作用的机制。
