title: Glycated albumin causes pancreatic β-cells dysfunction through autophagy dysfunction.
abstract: Growing evidence suggests that advanced glycation end-products (AGEs) are cytotoxic to pancreatic β-cells. The aims of this study were to investigate whether glycated albumin (GA), an early precursor of AGEs, would induce dysfunction in pancreatic β-cells and to determine which kinds of cellular mechanisms are activated in GA-induced β-cell apoptosis. Decreased viability and increased apoptosis were induced in INS-1 cells treated with 2.5 mg/mL GA under 16.7mM high-glucose conditions. Insulin content and glucose-stimulated secretion from isolated rat islets were reduced in 2.5 mg/mL GA-treated cells. In response to 2.5 mg/mL GA in INS-1 cells, autophagy induction and flux decreased as assessed by green fluorescent protein-microtubule-associated protein 1 light chain 3 dots, microtubule-associated protein 1 light chain 3-II conversion, and SQSTM1/p62 in the presence and absence of bafilomycin A1. Accumulated SQSTM1/p62 through deficient autophagy activated the nuclear factor-κB (p65)-inducible nitric oxide synthase-caspase-3 cascade, which was restored by treatment with small interfering RNA against p62. Small interfering RNA treatment against autophagy-related protein 5 significantly inhibited the autophagy machinery resulting in a significant increase in iNOS-cleaved caspase-3 expression. Treatment with 500μM 4-phenyl butyric acid significantly alleviated the expression of endoplasmic reticulum stress markers and iNOS in parallel with upregulated autophagy induction. However, in the presence of bafilomycin A1, the decreased viability of INS-1 cells was not recovered. Glycated albumin, an early precursor of AGE, caused pancreatic β-cell death by inhibiting autophagy induction and flux, resulting in nuclear factor-κB (p65)-iNOS-caspase-3 cascade activation as well as by increasing susceptibility to endoplasmic reticulum stress and oxidative stress.
authors.affiliation: Brain Korea 21 Project for Medical Science, Seoul 120-752, Korea.
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Song
authors.forename: Sun Ok
authors.initials: SO
authors.lastname: Song
authors.forename: Young-Hye
authors.initials: YH
authors.lastname: You
authors.forename: Kun-Ho
authors.initials: KH
authors.lastname: Yoon
authors.forename: Eun Seok
authors.initials: ES
authors.lastname: Kang
authors.forename: Bong Soo
authors.initials: BS
authors.lastname: Cha
authors.forename: Hyun Chul
authors.initials: HC
authors.lastname: Lee
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Kim
authors.forename: Byung-Wan
authors.initials: BW
authors.lastname: Lee
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001343:Autophagy / Q000187:drug effects*; D000071187:Autophagy-Related Protein 5; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005947:Glucose / Q000494:pharmacology; D017127:Glycation End Products, Advanced; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D050417:Insulin-Secreting Cells / Q000187:drug effects* / Q000378:metabolism; D007340:Insulinoma / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000071456:Sequestosome-1 Protein; D012709:Serum Albumin / Q000494:pharmacology*; D051996:Transcription Factor RelA / Q000378:metabolism; D000093423:Glycated Serum Albumin
chemical_list: D000071187:Autophagy-Related Protein 5; D053148:Caspase 3; D005947:Glucose; D017127:Glycation End Products, Advanced; D049452:Green Fluorescent Proteins; D006360:Heat-Shock Proteins; D007328:Insulin; D008869:Microtubule-Associated Proteins; D052247:Nitric Oxide Synthase Type II; D011506:Proteins; D000071456:Sequestosome-1 Protein; D012709:Serum Albumin; D051996:Transcription Factor RelA; D000093423:Glycated Serum Albumin; C545865:Atg5 protein, rat; C526109:Anxa3 protein, rat; C491079:Sqstm1 protein, rat