title: Unique cellular and mitochondrial defects mediate FK506-induced islet β-cell dysfunction.
abstract: OBJECTIVE
  To determine biological mechanisms involved in posttransplantation diabetes mellitus caused by the immunosuppressant tacrolimus (FK506).
  
  
  METHODS
  INS-1 cells and isolated rat islets were incubated with vehicle or FK506 and harvested at 24-hr intervals. Cells were assessed for viability, apoptosis, proliferation, cell insulin secretion, and content. Gene expression studies by microarray analysis, quantitative polymerase chain reaction, and motifADE analysis of the microarray data identified potential FK506-mediated pathways and regulatory motifs. Mitochondrial functions, including cell respiration, mitochondrial content, and bioenergetics were assessed.
  
  
  RESULTS
  Cell replication, viability, insulin secretion, oxygen consumption, and mitochondrial content were decreased (P<0.05) 1.2-, 1.27-, 1.77-, 1.32-, and 1.43-fold, respectively, after 48-hr FK506 treatment. Differences increased with time. FK506 (50 ng/mL) and cyclosporine A (800 ng/mL) had comparable effects. FK506 significantly decreased mitochondrial content and mitochondrial bioenergetics and showed a trend toward decreased oxygen consumption in isolated islets. Cell apoptosis and proliferation, mitochondrial DNA copy number, and ATP:ADP ratios were not significantly affected. Pathway analysis of microarray data showed FK506 modification of pathways involving ATP metabolism, membrane trafficking, and cytoskeleton remodeling. PGC1-α mRNA was down-regulated by FK506. MotifADE identified nuclear factor of activated T-cells, an important mediator of β-cell survival and function, as a potential factor mediating both up- and down-regulation of gene expression.
  
  
  CONCLUSIONS
  At pharmacologically relevant concentrations, FK506 decreases insulin secretion and reduces mitochondrial density and function without changing apoptosis rates, suggesting that posttransplantation diabetes induced by FK506 may be mediated by its effects on mitochondrial function.
authors.affiliation: Division of Endocrinology, Department of Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: Nassir
authors.initials: N
authors.lastname: Rostambeigi
authors.forename: Ian R
authors.initials: IR
authors.lastname: Lanza
authors.forename: Petras P
authors.initials: PP
authors.lastname: Dzeja
authors.forename: Michael C
authors.initials: MC
authors.lastname: Deeds
authors.forename: Brian A
authors.initials: BA
authors.lastname: Irving
authors.forename: Honey V
authors.initials: HV
authors.lastname: Reddi
authors.forename: Pranathi
authors.initials: P
authors.lastname: Madde
authors.forename: Song
authors.initials: S
authors.lastname: Zhang
authors.forename: Yan W
authors.initials: YW
authors.lastname: Asmann
authors.forename: Jarett M
authors.initials: JM
authors.lastname: Anderson
authors.forename: Jill M
authors.initials: JM
authors.lastname: Schimke
authors.forename: K Sreekumaran
authors.initials: KS
authors.lastname: Nair
authors.forename: Norman L
authors.initials: NL
authors.lastname: Eberhardt
authors.forename: Yogish C
authors.initials: YC
authors.lastname: Kudva
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D016572:Cyclosporine / Q000633:toxicity; D004272:DNA, Mitochondrial / Q000032:analysis; D020869:Gene Expression Profiling; D007166:Immunosuppressive Agents / Q000633:toxicity*; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects*; D008928:Mitochondria / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D016559:Tacrolimus / Q000633:toxicity*
chemical_list: D004272:DNA, Mitochondrial; D007166:Immunosuppressive Agents; D007328:Insulin; D016572:Cyclosporine; D000255:Adenosine Triphosphate; D016559:Tacrolimus