Regulation of the susceptibility to oxidative stress by cysteine availability in pancreatic beta-cells.
Pancreatic beta-cells are susceptible to oxidative stress, which is related closely to the islet dysfunction. In the present study, using the pancreatic cell lines HIT-T15 and RINm5F as known in vitro models of impaired beta-cell function as well as primary rat islet beta-cells, we observed a relationship between intracellular glutathione levels and oxidative stress-mediated cell dysfunction. Hydrogen peroxide and 4-hydroxy-2-nonenal caused cell death in HIT-T15 and RINm5F cells at lower concentrations compared with non-beta-cells, such as HepG2 and NRK-49F cells. The extent of the cytotoxicity caused by the model oxidants was inversely correlated well with intracellular glutathione levels in the cell lines used. Treatment of HIT-T15 and RINm5F cells with l-cysteine or l-cystine significantly augmented the glutathione contents, surpassing the effect of N-acetylcysteine, and abrogated 4-hydroxy-2-nonenal-mediated cytotoxicity almost completely. l-Cysteine increased intracellular glutathione levels in primary beta-cells as well. Supplementation of l-cysteine to the RINm5F cell culture inhibited 4-hydroxy-2-nonenal-mediated cytosolic translocation of PDX-1, a key transcription factor for beta-cell function. Intrinsic transport activities (V(max)/K(m)) of the l-cystine/l-glutamate exchanger in HIT-T15 and RINm5F cells were considerably lower than that in NRK-49F cells, although gene expressions of the exchanger were similar in these cells. Results obtained from the present study suggest that the restricted activity of the l-cystine/l-glutamate exchanger controls the levels of intracellular glutathione, thereby making beta-cells become susceptible to oxidative stress.
Numazawa
Satoshi
S
Dept. of Biochemical Toxicology, School of Pharmaceutical Sciences, Showa Univ., 1-5-8 Hatanodai, Shinagawa, Tokyo 142-8555, Japan. numazawa@pharm.showa-u.ac.jp
Sakaguchi
Harumi
H
Aoki
Risa
R
Taira
Toshio
T
Yoshida
Takemi
T
D000111:Acetylcysteine / Q000378:metabolism / Q000493:pharmacokinetics; D000447:Aldehydes / Q000494:pharmacology; D027182:Amino Acid Transport System y+ / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D001692:Biological Transport / Q000502:physiology; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003545:Cysteine / Q000378:metabolism* / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D005978:Glutathione / Q000037:antagonists & inhibitors / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D018384:Oxidative Stress / Q000502:physiology*; D021381:Protein Transport / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D015534:Trans-Activators / Q000378:metabolism
D000447:Aldehydes; D027182:Amino Acid Transport System y+; D018398:Homeodomain Proteins; D015534:Trans-Activators; C084010:pancreatic and duodenal homeobox 1 protein; D019328:Buthionine Sulfoximine; D006861:Hydrogen Peroxide; D005978:Glutathione; C027576:4-hydroxy-2-nonenal; D003545:Cysteine; D000111:Acetylcysteine