title: Insulin-secreting beta-cell dysfunction induced by human lipoproteins.
abstract: Diabetes is associated with significant changes in plasma concentrations of lipoproteins. We tested the hypothesis that lipoproteins modulate the function and survival of insulin-secreting cells. We first detected the presence of several receptors that participate in the binding and processing of plasma lipoproteins and confirmed the internalization of fluorescent low density lipoprotein (LDL) and high density lipoprotein (HDL) particles in insulin-secreting beta-cells. Purified human very low density lipoprotein (VLDL) and LDL particles reduced insulin mRNA levels and beta-cell proliferation and induced a dose-dependent increase in the rate of apoptosis. In mice lacking the LDL receptor, islets showed a dramatic decrease in LDL uptake and were partially resistant to apoptosis caused by LDL. VLDL-induced apoptosis of beta-cells involved caspase-3 cleavage and reduction in the levels of the c-Jun N-terminal kinase-interacting protein-1. In contrast, the proapoptotic signaling of lipoproteins was antagonized by HDL particles or by a small peptide inhibitor of c-Jun N-terminal kinase. The protective effects of HDL were mediated, in part, by inhibition of caspase-3 cleavage and activation of Akt/protein kinase B. In conclusion, human lipoproteins are critical regulators of beta-cell survival and may therefore contribute to the beta-cell dysfunction observed during the development of type 2 diabetes.
authors.affiliation: Department of Internal Medicine and Institute of Cellular Biology and Morphology, University Hospital, Lausanne 1011, Switzerland.
authors.forename: Marc-Estienne
authors.initials: ME
authors.lastname: Roehrich
authors.forename: Vincent
authors.initials: V
authors.lastname: Mooser
authors.forename: Vincent
authors.initials: V
authors.lastname: Lenain
authors.forename: Joachim
authors.initials: J
authors.lastname: Herz
authors.forename: Johannes
authors.initials: J
authors.lastname: Nimpf
authors.forename: Salman
authors.initials: S
authors.lastname: Azhar
authors.forename: Martine
authors.initials: M
authors.lastname: Bideau
authors.forename: Alessandro
authors.initials: A
authors.lastname: Capponi
authors.forename: Pascal
authors.initials: P
authors.lastname: Nicod
authors.forename: Jacques-Antoine
authors.initials: JA
authors.lastname: Haefliger
authors.forename: Gérard
authors.initials: G
authors.lastname: Waeber
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002455:Cell Division; D002470:Cell Survival; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000378:metabolism; D004789:Enzyme Activation; D006801:Humans; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D008074:Lipoproteins / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D018076:DNA, Complementary; D007328:Insulin; D008074:Lipoproteins; D008077:Lipoproteins, LDL; D008079:Lipoproteins, VLDL; D011518:Proto-Oncogene Proteins; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases