The protective effect of alpha-tocopherol against dichromate-induced renal tight junction damage is mediated via ERK1/2.
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.
Arreola-Mendoza
Laura
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.
Del Razo
Luz M
LM
Mendoza-Garrido
Maria E
ME
Martin
Dolores
D
Namorado
Maria C
MC
Calderon-Salinas
Jose V
JV
Reyes
Jose L
JL
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D015153:Blotting, Western; D002499:Centrifugation, Density Gradient; D002840:Chromates / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D002857:Chromium / Q000633:toxicity; D057167:Claudins; D003404:Creatinine / Q000378:metabolism; D005260:Female; D005455:Fluorescent Antibody Technique; D005947:Glucose / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008315:Malondialdehyde / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D019950:Mitogen-Activated Protein Kinase 1 / Q000502:physiology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000502:physiology*; D062793:Occludin; D051381:Rats; D017208:Rats, Wistar; D019108:Tight Junctions / Q000187:drug effects* / Q000201:enzymology* / Q000473:pathology; D024502:alpha-Tocopherol / Q000494:pharmacology*
D000975:Antioxidants; D002840:Chromates; D057167:Claudins; C491874:Cldn2 protein, rat; D008565:Membrane Proteins; D062793:Occludin; C568987:Ocln protein, rat; D002857:Chromium; D008315:Malondialdehyde; D003404:Creatinine; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D024502:alpha-Tocopherol; D005947:Glucose