title: MiRNA-21 reverses high glucose and high insulin induced insulin resistance in 3T3-L1 adipocytes through targeting phosphatase and tensin homologue.
abstract: OBJECTIVE
  Our previous study showed there was a change of microRNA (miRNA) expression profile, and miR-21 was significantly down regulated in insulin-resistant adipocytes (IR-adipocytes). Phosphatase and tensin homologs deleted on chromosome 10 (PTEN), a negative regulator of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, was identified to be a target gene of miR-21, which suggested miR-21 might be associated with insulin resistance (IR) or diabetes. However, it is not known whether miR-21 play any role in the development of IR in 3T3-L1 adipocytes.
  
  
  METHODS
  Normal adipocytes and adipocytes transfected with pre-miR-21(pmiR-21) or negative control (pNeg) were treated with high glucose and high insulin for 24 h, insulin-stimulated glucose uptake was determined by 2-Deoxyglucose transport assay, miR-21 expression level was measured by using quantitative real-time RT-PCR (qRT-PCR). The protein expression levels of PTEN, Akt, phospho-Akt (Ser473), IRβ, GSK3β, phospho-GSK3β (Ser9) and GLUT4 were detected by western blotting assay.
  
  
  RESULTS
  We further confirmed that miR-21 was down regulated in IR-adipocytes by qRT-PCR. Over-expression of miR-21 significantly increased insulin-induced glucose uptake and decreased PTEN protein expression, while it had no significant effect on PTEN mRNA expression in IR-adipocytes. Moreover, over-expressing miR-21 significantly increased insulin-induced phosphorylation of AKT (Ser473), GSK3β (Ser9) and the translocation of glucose transporter 4 (GLUT4) in IR-adipocytes.
  
  
  CONCLUSIONS
  In this study, our data demonstrate that miR-21 reverses high glucose and high insulin induced IR in 3T3-L1 adipocytes, possibly through modulating the PTEN-AKT pathway, and miR-21 may be a new therapeutic target for metabolic diseases such as T2DM and obesity.
authors.affiliation: Department of Physiology, School of Medicine, University of South China, Hengyang, China. linghongyan@126.com
authors.forename: H-Y
authors.initials: HY
authors.lastname: Ling
authors.forename: B
authors.initials: B
authors.lastname: Hu
authors.forename: X-B
authors.initials: XB
authors.lastname: Hu
authors.forename: J
authors.initials: J
authors.lastname: Zhong
authors.forename: S-D
authors.initials: SD
authors.lastname: Feng
authors.forename: L
authors.initials: L
authors.lastname: Qin
authors.forename: G
authors.initials: G
authors.lastname: Liu
authors.forename: G-B
authors.initials: GB
authors.lastname: Wen
authors.forename: D-F
authors.initials: DF
authors.lastname: Liao
mesh_terms: D041721:3T3-L1 Cells; D052438:Adipocytes, White / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D003847:Deoxyglucose / Q000378:metabolism; D015536:Down-Regulation; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006943:Hyperglycemia / Q000378:metabolism*; D006946:Hyperinsulinism / Q000378:metabolism*; D007333:Insulin Resistance; D051379:Mice; D035683:MicroRNAs / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D051275:Glucose Transporter Type 4; C531950:MIRN21 microRNA, mouse; D035683:MicroRNAs; D012333:RNA, Messenger; C495693:Slc2a4 protein, mouse; D003847:Deoxyglucose; D051059:PTEN Phosphohydrolase; C487757:Pten protein, mouse