title: Genetic variation in ATP5O is associated with skeletal muscle ATP50 mRNA expression and glucose uptake in young twins.
abstract: BACKGROUND
  Impaired oxidative capacity of skeletal muscle mitochondria contribute to insulin resistance and type 2 diabetes (T2D). Furthermore, mRNA expression of genes involved in oxidative phosphorylation, including ATP5O, is reduced in skeletal muscle from T2D patients. Our aims were to investigate mechanisms regulating ATP5O expression in skeletal muscle and association with glucose metabolism, and the relationship between ATP5O single nucleotide polymorphisms (SNPs) and risk of T2D.
  
  
  RESULTS
  ATP5O mRNA expression was analyzed in skeletal muscle from young (n = 86) and elderly (n = 68) non-diabetic twins before and after a hyperinsulinemic euglycemic clamp. 11 SNPs from the ATP5O locus were genotyped in the twins and a T2D case-control cohort (n = 1466). DNA methylation of the ATP5O promoter was analyzed in twins (n = 22) using bisulfite sequencing. The mRNA level of ATP5O in skeletal muscle was reduced in elderly compared with young twins, both during basal and insulin-stimulated conditions (p<0.0005). The degree of DNA methylation around the transcription start of ATP5O was <1% in both young and elderly twins and not associated with mRNA expression (p = 0.32). The mRNA level of ATP5O in skeletal muscle was positively related to insulin-stimulated glucose uptake (regression coefficient = 6.6; p = 0.02). Furthermore, two SNPs were associated with both ATP5O mRNA expression (rs12482697: T/T versus T/G; p = 0.02 and rs11088262: A/A versus A/G; p = 0.004) and glucose uptake (rs11088262: A/A versus A/G; p = 0.002 and rs12482697: T/T versus T/G; p = 0.005) in the young twins. However, we could not detect any genetic association with T2D.
  
  
  CONCLUSIONS
  Genetic variation and age are associated with skeletal muscle ATP5O mRNA expression and glucose disposal rate, suggesting that combinations of genetic and non-genetic factors may cause the reduced expression of ATP5O in T2D muscle. These findings propose a role for ATP5O, in cooperation with other OXPHOS genes, in the regulation of in vivo glucose metabolism.
authors.affiliation: Department of Clinical Sciences, Diabetes and Endocrinology Research Unit, CRC Malmö University Hospital, Lund University, Malmö, Sweden. tina.ronn@med.lu.se
authors.forename: Tina
authors.initials: T
authors.lastname: Rönn
authors.forename: Pernille
authors.initials: P
authors.lastname: Poulsen
authors.forename: Tiinamaija
authors.initials: T
authors.lastname: Tuomi
authors.forename: Bo
authors.initials: B
authors.lastname: Isomaa
authors.forename: Leif
authors.initials: L
authors.lastname: Groop
authors.forename: Allan
authors.initials: A
authors.lastname: Vaag
authors.forename: Charlotte
authors.initials: C
authors.lastname: Ling
mesh_terms: D000328:Adult; D000367:Age Factors; D019175:DNA Methylation; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D025261:Mitochondrial Proton-Translocating ATPases / Q000235:genetics*; D018482:Muscle, Skeletal / Q000201:enzymology*; D010085:Oxidative Phosphorylation; D010086:Oxidative Phosphorylation Coupling Factors / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000032:analysis; D014427:Twins / Q000235:genetics
chemical_list: D010086:Oxidative Phosphorylation Coupling Factors; D012333:RNA, Messenger; C000628217:F(6) ATPase; D025261:Mitochondrial Proton-Translocating ATPases; D005947:Glucose