title: AMP-activated protein kinase agonist dose dependently improves function and reduces apoptosis in glucotoxic beta-cells without changing triglyceride levels.
abstract: Prolonged hyperglycaemia leads to impaired glucose-stimulated insulin secretion (GSIS) and apoptosis in insulin-producing beta-cells. The detrimental effects have been connected with glucose-induced lipid accumulation in the beta-cell. AMP-activated protein kinase (AMPK) agonist, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), promotes utilization of nutrient stores for energy production. It was tested how impaired GSIS and elevated apoptosis observed in insulinoma (INS)-1E cells after prolonged culture at 27 mM glucose were affected by the inclusion of 0.3 or 1 mM AICAR during culture. Glucose-induced impairment of insulin release was reverted by the inclusion of 0.3 but not 1 mM AICAR, which did not affect insulin content. The glucose-induced rise in triglyceride (TG) content observed in the cells cultured at 27 mM glucose was not altered by the inclusion of either 0.3 or 1 mM AICAR. Inclusion of 1 but not 0.3 mM AICAR during culture induced phosphorylation of AMPK and its downstream target acyl-CoA carboxylase. Phosphorylation was paralleled by reduced number of apoptotic cells and lowered expression of pro-apoptotic C/EBP homologous protein (CHOP). In conclusion, AICAR dose dependently improves beta-cell function and reduces apoptosis in beta-cells exposed to prolonged hyperglycaemia without changing TG levels.
authors.affiliation: Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden. hanna.nyblom@mcb.uu.se
authors.forename: Hanna K
authors.initials: HK
authors.lastname: Nyblom
authors.forename: Ernest
authors.initials: E
authors.lastname: Sargsyan
authors.forename: Peter
authors.initials: P
authors.lastname: Bergsten
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015415:Biomarkers / Q000378:metabolism; D019735:Carbon-Carbon Ligases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005947:Glucose / Q000633:toxicity*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D010766:Phosphorylation / Q000187:drug effects; D012265:Ribonucleotides / Q000494:pharmacology*; D051742:Transcription Factor CHOP / Q000378:metabolism; D014280:Triglycerides / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D007328:Insulin; D012265:Ribonucleotides; D014280:Triglycerides; D051742:Transcription Factor CHOP; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; D019735:Carbon-Carbon Ligases; C018757:acyl-CoA carboxylase; C031143:AICA ribonucleotide; D005947:Glucose