Cyclosporin and tacrolimus impair insulin secretion and transcriptional regulation in INS-1E beta-cells.
OBJECTIVE
Introducing the calcineurin inhibitors cyclosporin (CsA) and tacrolimus (Tac) has improved the outcome of organ transplants, but complications such as new onset diabetes mellitus after transplantation (NODAT) decrease survival rates.


METHODS
We sought, in a beta-cell culture model, to elucidate the pathogenic mechanisms behind NODAT and the relative contribution of the calcineurin inhibitors. INS-1E cells were incubated at basal and stimulatory glucose concentrations, while exposed to pharmacologically relevant doses of CsA, Tac and vehicle for 6 or 24 h.


RESULTS
Tac inhibited basal (P < 0.05), but not glucose-stimulated insulin secretion (GSIS) after 6 h of exposure. After 24 h, both agents inhibited basal and GSIS (P < 0.05). Calcineurin phosphatase activity was decreased by both drugs during all conditions. Apoptosis was only seen with CsA treatment, which also induced a slight suppression of calcineurin and insulin mRNA, as well as increased levels of the sterol receptor element binding protein (SREBP)-1c, a transcription factor thought to suppress genes essential for beta-cell function and induce insulin resistance. Expression levels of nuclear factor of activated T-cells (NFAT)-c1, -c2, -c3 and -c4 were not decreased notably by either drug.


CONCLUSIONS
Tac had acute inhibitory effects on basal insulin secretion, but prolonged exposure (24 h) to Tac or CsA revealed similar suppression of insulin secretion. These prolonged effects were mirrored by a total inhibition of calcineurin activity in beta-cells. CsA showed greater inhibition of beta-cell survival and transcriptional markers, essential for beta-cell function.
Øzbay
L A
LA
Department of Nephrology, Aarhus University Hospital, Skejby, Aarhus, Denmark. doc.aygen@gmail.com
Smidt
K
K
Mortensen
D M
DM
Carstens
J
J
Jørgensen
K A
KA
Rungby
J
J
D000818:Animals; D001483:Base Sequence; D019703:Calcineurin / Q000378:metabolism; D065095:Calcineurin Inhibitors; D002460:Cell Line; D016572:Cyclosporine / Q000494:pharmacology*; D017931:DNA Primers; D004797:Enzyme-Linked Immunosorbent Assay; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D007328:Insulin / Q000235:genetics / Q000378:metabolism*; D007333:Insulin Resistance; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000378:metabolism; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D016559:Tacrolimus / Q000494:pharmacology*
D065095:Calcineurin Inhibitors; D017931:DNA Primers; D007166:Immunosuppressive Agents; D007328:Insulin; D050778:NFATC Transcription Factors; D012333:RNA, Messenger; D016572:Cyclosporine; D019703:Calcineurin; D016559:Tacrolimus
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