Hals 2012 Biochem Biophys Res Commun
| Hals IK, Ogata H, Pettersen E, Ma Z, BjΓΆrklund A, Skorpen F, Egeberg KW, Grill V (2012) Marked over expression of uncoupling protein-2 in beta cells exerts minor effects on mitochondrial metabolism. Biochem Biophys Res Commun 423: 259-264. |
Hals IK, Ogata H, Pettersen E, Ma Z, Bjoerklund A, Skorpen F, Egeberg KW, Grill V (2012) Biochem Biophys Res Commun
Abstract: Evidence is conflicting as to the impact of elevated levels of uncoupling protein-2 (UCP-2) on insulin-producing beta cells. Here we investigated effects of a fourfold induction of UCP-2 protein primarily on mitochondrial parameters and tested for replication of positive findings at a lower level of induction. We transfected INS-1 cells to obtain a tet-on inducible cell line. A 48 h exposure to 1 ΞΌg/ml of doxycycline (dox) induced UCP-2 fourfold (424 Β± 113%, mean Β± SEM) and 0.1 ΞΌg/ml twofold (178 Β± 29%, n = 3). Fourfold induced cells displayed normal viability (MTT, apoptosis), normal cellular insulin contents and, glucose-induced insulin secretion (+27 Β± 11%) as well as D-[U-(14)C]-glucose oxidation (+5 Β± 9% at 11 mM glucose). Oxidation of [1-(14)C]-oleate was increased from 4088 to 5797 fmol/ΞΌg prot/2h at 3.3 mM glucose, p< 0.03. Oxidation of L-[(14)C(U)]-glutamine was unaffected. Induction of UCP-2 did not significantly affect measures of mitochondrial membrane potential (Rhodamine 123) or mitochondrial mass (Mitotracker Green) and did not affect ATP levels. Oligomycin-inhibited oxygen consumption (a measure of mitochondrial uncoupling) was marginally increased, the effect being significant in comparison with dox-only treated cells, p< 0.05. Oxygen radicals, assessed by dichlorofluorescin diacetate, were decreased by 30%, p< 0.025.Testing for the lower level of UCP-2 induction did not reproduce any of the positive findings. A fourfold induction of UCP-2 was required to exert minor metabolic effects. These findings question an impact of moderately elevated UCP-2 levels in beta cells as seen in diabetes. β’ Keywords: Uncoupling protein-2, insulin secretion, fatty acid oxidation, INS-1 cells
Labels: MiParea: Respiration, Genetic knockout; overexpression"Genetic knockout; overexpression" is not in the list (Respiration, Instruments;methods, mt-Biogenesis;mt-density, mt-Structure;fission;fusion, mt-Membrane, mtDNA;mt-genetics, nDNA;cell genetics, Genetic knockout;overexpression, Comparative MiP;environmental MiP, Gender, ...) of allowed values for the "MiP area" property.
Tissue;cell: Islet Cell; Pancreas; Thymus"Islet Cell; Pancreas; Thymus" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property.
Enzyme: Uncoupling protein Regulation: Fatty Acid"Fatty Acid" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property.
HRR: Oxygraph-2k
