Tissue factor/factor VIIa signalling promotes cytokine-induced beta cell death and impairs glucose-stimulated insulin secretion from human pancreatic islets.
OBJECTIVE
Patients diagnosed with type 1 or type 2 diabetes have elevated levels of coagulation factor VIIa (FVIIa) and its receptor tissue factor (TF) in their bloodstream. This may affect the fate of the beta cells. We aimed to study the effects of TF/FVIIa signalling on cytokine-induced beta cell death and islet function in vitro.


METHODS
Human pancreatic islets and MIN-6 beta cells were used to study TF mRNA and protein expression using real-time PCR, immunoblotting and flow cytometry. The effects of TF/FVIIa on cytokine-induced beta cell death were studied in MIN-6 cells and human pancreatic islets using cell-death ELISA and propidium iodide and cleaved caspase-3 staining. Effects of TF/FVIIa on the phosphorylation of p38, extracellular signal-regulated kinase and c-Jun N-terminal kinase (JNK) were investigated by immunoblotting. Glucose-stimulated insulin secretion (GSIS) from human islets was measured with an insulin ELISA.


RESULTS
A combination of the cytokines IL-1β, TNF-α and IFN-γ induced TF expression in human pancreatic islets and in beta cells. TF/FVIIa did not affect basal beta cell death but, independently of downstream coagulation activity, augmented beta cell death in response to cytokines. The effect of TF/FVIIa on cytokine-induced beta cell death was found to be dependent on the stress kinase JNK, since FVIIa addition potentiated cytokine-induced JNK activation and JNK inhibition abolished the effect of TF/FVIIa on cytokine-induced beta cell death. Moreover, TF/FVIIa signalling resulted in inhibition of GSIS from human pancreatic islets.


CONCLUSIONS
These results indicate that TF/FVIIa signalling has a negative effect on beta cell function and promotes beta cell death in response to cytokines.
Department of Medical Sciences, Clinical Chemistry, Science for Life Laboratory, University Hospital, Uppsala University, Entr. 61 3rd floor, S-751 85, Uppsala, Sweden.
Desirée
D
Edén
Department of Medical Sciences, Clinical Chemistry, Science for Life Laboratory, University Hospital, Uppsala University, Entr. 61 3rd floor, S-751 85, Uppsala, Sweden.
Agneta
A
Siegbahn
Department of Medical Sciences, Clinical Chemistry, Science for Life Laboratory, University Hospital, Uppsala University, Entr. 61 3rd floor, S-751 85, Uppsala, Sweden. dariush.mokhtari@medsci.uu.se.
Dariush
D
Mokhtari
D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects / Q000502:physiology*; D016207:Cytokines / Q000494:pharmacology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015942:Factor VIIa / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism*; D007371:Interferon-gamma / Q000494:pharmacology; D053583:Interleukin-1beta / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013925:Thromboplastin / Q000235:genetics / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D016207:Cytokines; D007328:Insulin; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D013925:Thromboplastin; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D015942:Factor VIIa; D053148:Caspase 3; D005947:Glucose
Beta cells; Cytokines; Diabetes; FVIIa; Glucose-stimulated insulin secretion; JNK; Pancreatic islets; Tissue factor