title: Decreased N(6)-methyladenosine in peripheral blood RNA from diabetic patients is associated with FTO expression rather than ALKBH5.
abstract: BACKGROUND
  N(6)-methyladenosine (m(6)A) modification plays a fundamental role in the epigenetic regulation of the mammalian transcriptome. m(6)A can be demethylated by fat mass- and obesity-associated (FTO) protein and α-ketoglutarate-dependent dioxygenase alkB homolog 5 (ALKBH5) protein. However, the importance of m(6)A alteration in type 2 diabetes mellitus (T2DM) has not been explored.
  
  
  OBJECTIVE
  The objective of the study was to investigate whether m(6)A content was reduced in T2DM patients and whether m(6)A content was correlated with the mRNA expression levels of the FTO and ALKBH5 genes.
  
  
  METHODS
  In this case-control study, peripheral blood samples were obtained from 88 T2DM patients and 92 healthy controls. For the diabetic animal model experiment, blood samples were obtained from seven diabetic and eight nondiabetic rats. A sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry method was developed for the determination of the m(6)A content in RNA, quantitative real-time PCR was used to examine the mRNA expression levels of the FTO and ALKBH5 genes, and high-resolution melting and DNA sequencing were used to detect FTO single-nucleotide polymorphisms.
  
  
  RESULTS
  Our results showed that the m(6)A contents in the RNA from T2DM patients and diabetic rats were significantly lower compared with the control groups (P = 2.6 × 10(-24) for T2DM patients; P = .001 for diabetic rats, respectively), and T2DM can be characterized by the content of m(6)A. The mRNA expression level of FTO was significantly higher in T2DM patients than that of the controls (P = .0007) and was associated with the risk of T2DM (odds ratio 2.797, 95% confidence interval 1.452-5.389, P = .002). Moreover, the m(6)A contents were correlated with FTO mRNA expression.
  
  
  CONCLUSIONS
  These data suggest that the increased mRNA expression of FTO could be responsible for the reduction of m(6)A in T2DM, which may further increase the risk of complications of T2DM. Low m(6)A should be investigated further as a novel potential biomarker of T2DM.
authors.affiliation: Center for Gene Diagnosis (F.S., J.-T.H., Y.Y., S.-M.L.), Zhongnan Hospital of Wuhan University, Wuhan 430071, People's Republic of China; Key Laboratory of Analytical Chemistry for Biology and Medicine (F.S., W.H., J.X., Y.-Q.F., B.-F.Y.) (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, People's Republic of China; Center for Animal Experiment/ABSL-3 Laboratory (K.W.), Wuhan University, Wuhan 430071, People's Republic of China; Department of Chemical Biology (G.-F.J.), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China; and Department of Epidemiology (J.C.), The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030.
authors.forename: Fan
authors.initials: F
authors.lastname: Shen
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Jing-Tao
authors.initials: JT
authors.lastname: Huang
authors.forename: Jun
authors.initials: J
authors.lastname: Xiong
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.forename: Ke
authors.initials: K
authors.lastname: Wu
authors.forename: Gui-Fang
authors.initials: GF
authors.lastname: Jia
authors.forename: Jinyun
authors.initials: J
authors.lastname: Chen
authors.forename: Yu-Qi
authors.initials: YQ
authors.lastname: Feng
authors.forename: Bi-Feng
authors.initials: BF
authors.lastname: Yuan
authors.forename: Song-Mei
authors.initials: SM
authors.lastname: Liu
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000097:blood; D000071502:AlkB Homolog 5, RNA Demethylase; D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; D000818:Animals; D015415:Biomarkers / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D049308:Dioxygenases / Q000235:genetics / Q000378:metabolism*; D044127:Epigenesis, Genetic; D005260:Female; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats
chemical_list: D015415:Biomarkers; D008565:Membrane Proteins; D011506:Proteins; C010223:N-methyladenosine; D049308:Dioxygenases; C559920:ALKBH5 protein, human; D000071502:AlkB Homolog 5, RNA Demethylase; D000071516:Alpha-Ketoglutarate-Dependent Dioxygenase FTO; C526492:FTO protein, human; D000241:Adenosine