Fibrillar islet amyloid polypeptide differentially affects oxidative mechanisms and lipoprotein uptake in correlation with cytotoxicity in two insulin-producing cell lines.
We reported recently that fibrillar human islet amyloid polypeptide (IAPP) is cytotoxic to RIN5mF cells but not to HIT-T15 cells, both being insulin-producing cell lines. In the present study, we explored the basis for this difference by studying oxidative stress responses and low density lipoprotein (LDL) binding and uptake. In RINm5F but not in HIT-T15 cells, plasma membrane NADPH oxidase activity and intracellular lipid peroxidation increased by challenge with IAPP fibrils for 24 h (10 microM), whereas glutathione peroxidase activity was not changed. Furthermore, although both cell lines express (125)I-LDL binding sites, IAPP fibrils increased (125)I-LDL binding and uptake only in RINm5F cells and not in HIT-T15 cells. The cytotoxic action of IAPP fibrils in RINm5F cells is therefore paralleled by increased oxidative responses and LDL uptake, suggesting that cytotoxic mechanisms of IAPP fibrils in insulin-producing cells involve changes in pathways of cellular oxidative stress systems and lipid homeostasis.
Janciauskiene
S
S
Department of Medicine, Lund University, Malmö, SE-205 02, Sweden.
Ahrén
B
B
D000682:Amyloid / Q000633:toxicity*; D000818:Animals; D001665:Binding Sites; D001693:Biological Transport, Active / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D006801:Humans; D007328:Insulin / Q000096:biosynthesis*; D058228:Islet Amyloid Polypeptide; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000187:drug effects; D008077:Lipoproteins, LDL / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats
D000682:Amyloid; D007328:Insulin; D058228:Islet Amyloid Polypeptide; D008077:Lipoproteins, LDL; D019255:NADPH Oxidases