title: Global microRNA expression profiles in insulin target tissues in a spontaneous rat model of type 2 diabetes.
abstract: OBJECTIVE
  MicroRNAs regulate a broad range of biological mechanisms. To investigate the relationship between microRNA expression and type 2 diabetes, we compared global microRNA expression in insulin target tissues from three inbred rat strains that differ in diabetes susceptibility.
  
  
  METHODS
  Using microarrays, we measured the expression of 283 microRNAs in adipose, liver and muscle tissue from hyperglycaemic (Goto-Kakizaki), intermediate glycaemic (Wistar Kyoto) and normoglycaemic (Brown Norway) rats (n = 5 for each strain). Expression was compared across strains and validated using quantitative RT-PCR. Furthermore, microRNA expression variation in adipose tissue was investigated in 3T3-L1 adipocytes exposed to hyperglycaemic conditions.
  
  
  RESULTS
  We found 29 significantly differentiated microRNAs (p(adjusted) < 0.05): nine in adipose tissue, 18 in liver and two in muscle. Of these, five microRNAs had expression patterns that correlated with the strain-specific glycaemic phenotype. MiR-222 (p(adjusted) = 0.0005) and miR-27a (p(adjusted) = 0.006) were upregulated in adipose tissue; miR-195 (p(adjusted) = 0.006) and miR-103 (p(adjusted) = 0.04) were upregulated in liver; and miR-10b (p(adjusted) = 0.004) was downregulated in muscle. Exposure of 3T3-L1 adipocytes to increased glucose concentration upregulated the expression of miR-222 (p = 0.008), miR-27a (p = 0.02) and the previously reported miR-29a (p = 0.02). Predicted target genes of these differentially expressed microRNAs are involved in pathways relevant to type 2 diabetes.
  
  
  CONCLUSIONS
  The expression patterns of miR-222, miR-27a, miR-195, miR-103 and miR-10b varied with hyperglycaemia, suggesting a role for these microRNAs in the pathophysiology of type 2 diabetes, as modelled by the Gyoto-Kakizaki rat. We observed similar patterns of expression of miR-222, miR-27a and miR-29a in adipocytes as a response to increased glucose levels, which supports our hypothesis that altered expression of microRNAs accompanies primary events related to the pathogenesis of type 2 diabetes.
authors.affiliation: Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK.
authors.forename: B M
authors.initials: BM
authors.lastname: Herrera
authors.forename: H E
authors.initials: HE
authors.lastname: Lockstone
authors.forename: J M
authors.initials: JM
authors.lastname: Taylor
authors.forename: M
authors.initials: M
authors.lastname: Ria
authors.forename: A
authors.initials: A
authors.lastname: Barrett
authors.forename: S
authors.initials: S
authors.lastname: Collins
authors.forename: P
authors.initials: P
authors.lastname: Kaisaki
authors.forename: K
authors.initials: K
authors.lastname: Argoud
authors.forename: C
authors.initials: C
authors.lastname: Fernandez
authors.forename: M E
authors.initials: ME
authors.lastname: Travers
authors.forename: J P
authors.initials: JP
authors.lastname: Grew
authors.forename: J C
authors.initials: JC
authors.lastname: Randall
authors.forename: A L
authors.initials: AL
authors.lastname: Gloyn
authors.forename: D
authors.initials: D
authors.lastname: Gauguier
authors.forename: M I
authors.initials: MI
authors.lastname: McCarthy
authors.forename: C M
authors.initials: CM
authors.lastname: Lindgren
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D052436:Adipose Tissue, White / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology; D007328:Insulin / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D051379:Mice; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D051381:Rats; D011921:Rats, Inbred WKY; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D007328:Insulin; D035683:MicroRNAs; D005947:Glucose