title: Tumor necrosis factor-alpha-activated cell death pathways in NIT-1 insulinoma cells and primary pancreatic beta cells.
abstract: Tumor necrosis factor-alpha (TNFalpha) is a potential mediator of beta cell destruction in insulin-dependent diabetes mellitus. We have studied TNF-responsive pathways leading to apoptosis in beta cells. Primary beta cells express low levels of the type I TNF receptor (TNFR1) but do not express the type 2 receptor (TNFR2). Evidence for TNFR1 expression on beta cells came from flow cytometry using monoclonal antibodies specific for TNFR1 and TNFR2 and from RT-PCR of beta cell RNA. NIT-1 insulinoma cells similarly expressed TNFR1 (at higher levels than primary beta cells) as detected by flow cytometry and radio-binding studies. TNF induced NF-kappaB activation in both primary islet cells and NIT-1 cells. Apoptosis in response to TNFalpha was observed in NIT-1 cells whereas apoptosis of primary beta cells required both TNFalpha and interferon-gamma (IFNgamma). Apoptosis could be prevented in NIT-1 cells by expression of dominant negative Fas-associating protein with death domain (dnFADD). Apoptosis in NIT-1 cells was increased by coincubation with IFNgamma, which also increased caspase 1 expression. These data show that TNF-activated pathways capable of inducing apoptotic cell death are present in beta cells. Caspase activation is the dominant pathway of TNF-induced cell death in NIT-1 cells and may be an important mechanism of beta cell damage in insulin-dependent diabetes mellitus.
authors.affiliation: The Walter and Eliza Hall Institute of Medical Research, Post Office Royal Melbourne Hospital, Parkville, Victoria, Australia.
authors.forename: L A
authors.initials: LA
authors.lastname: Stephens
authors.forename: H E
authors.initials: HE
authors.lastname: Thomas
authors.forename: L
authors.initials: L
authors.lastname: Ming
authors.forename: M
authors.initials: M
authors.lastname: Grell
authors.forename: R
authors.initials: R
authors.lastname: Darwiche
authors.forename: L
authors.initials: L
authors.lastname: Volodin
authors.forename: T W
authors.initials: TW
authors.lastname: Kay
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D020170:Caspase 1 / Q000378:metabolism; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007340:Insulinoma / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016328:NF-kappa B / Q000502:physiology; D010190:Pancreatic Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D020170:Caspase 1