title: Deletion of protein kinase Cδ in mice modulates stability of inflammatory genes and protects against cytokine-stimulated beta cell death in vitro and in vivo.
abstract: OBJECTIVE
  Proinflammatory cytokines contribute to beta cell destruction in type 1 diabetes, but the mechanisms are incompletely understood. The aim of the current study was to address the role of the protein kinase C (PKC) isoform PKCδ, a diverse regulator of cell death, in cytokine-stimulated apoptosis in primary beta cells.
  
  
  METHODS
  Islets isolated from wild-type or Prkcd(-/-) mice were treated with IL-1β, TNF-α and IFNγ and assayed for apoptosis, nitric oxide (NO) generation and insulin secretion. Activation of signalling pathways, apoptosis and endoplasmic reticulum (ER) stress were determined by immunoblotting. Stabilisation of mRNA transcripts was measured by RT-PCR following transcriptional arrest. Mice were injected with multiple low doses of streptozotocin (MLD-STZ) and fasting blood glucose monitored.
  
  
  RESULTS
  Deletion of Prkcd inhibited apoptosis and NO generation in islets stimulated ex vivo with cytokines. It also delayed the onset of hyperglycaemia in MLD-STZ-treated mice. Activation of ERK, p38, JNK, AKT1, the ER stress markers DDIT3 and phospho-EIF2α and the intrinsic apoptotic markers BCL2 and MCL1 was not different between genotypes. However, deletion of Prkcd destabilised mRNA transcripts for Nos2, and for multiple components of the toll-like receptor 2 (TLR2) signalling complex, which resulted in disrupted TLR2 signalling.
  
  
  CONCLUSIONS
  Loss of PKCδ partially protects against hyperglycaemia in the MLD-STZ model in vivo, and against cytokine-mediated apoptosis in vitro. This is accompanied by reduced NO generation and destabilisation of Nos2 and components of the TLR2 signalling pathway. The results highlight a mechanism for regulating proinflammatory gene expression in beta cells independently of transcription.
authors.affiliation: Garvan Institute of Medical Research, St Vincent's Hospital, 384 Victoria Street, Darlinghurst, Sydney, NSW 2010, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Cantley
authors.forename: E
authors.initials: E
authors.lastname: Boslem
authors.forename: D R
authors.initials: DR
authors.lastname: Laybutt
authors.forename: D V
authors.initials: DV
authors.lastname: Cordery
authors.forename: G
authors.initials: G
authors.lastname: Pearson
authors.forename: L
authors.initials: L
authors.lastname: Carpenter
authors.forename: M
authors.initials: M
authors.lastname: Leitges
authors.forename: T J
authors.initials: TJ
authors.lastname: Biden
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D015153:Blotting, Western; D016207:Cytokines / Q000494:pharmacology*; D066298:In Vitro Techniques; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D007371:Interferon-gamma / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation / Q000187:drug effects; D016133:Polymerase Chain Reaction; D051745:Protein Kinase C-delta / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D016207:Cytokines; D053583:Interleukin-1beta; D007527:Isoenzymes; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D051745:Protein Kinase C-delta