title: Akt2 mediates TGF-β1-induced epithelial to mesenchymal transition by deactivating GSK3β/snail signaling pathway in renal tubular epithelial cells.
abstract: BACKGROUND
  The epithelial-mesenchymal transition (EMT) induced by growth factors or cytokines, particularly transforming growth factor-β (TGF-β1), plays an important role in kidney tubulointerstitial injury. However, signaling pathways mediating TGF-β1-induced EMT are not precisely known. In this study, we examined the role of Akt2 on EMT.
  
  
  METHODS
  HK-2 cells were exposed to 10 ng/ml TGF-β1 to establish a model of EMT. The expression of proteins were detected by western blot assay and Immunofluorescence. The levels of genes were tested by RT-PCR.
  
  
  RESULTS
  We found that treatment of HK-2 cells, a human proximal tubular cell line, with 10 ng/ml TGF-β1 resulted in activation of phosphatidylinositol 3-kinase (PI3K)/Akt2 signaling as evidenced by increased p-PI3K, Akt2 and p-Akt (Ser 473) expression. Importantly, TGF-β1 treatment decreased zona occludins 1 (ZO-1) and E-cadherin (epithelial markers) expression, increased fibronectin and vimentin (mesenchymal makers) expression, which were prevented by Ly294002 (the inhibitor of PI3K) or small interfering RNA (siAkt2), suggesting that Akt2 mediated TGF-β1-induced EMT. Meanwhile, RNA and protein levels of Snail1, the key inducer of EMT, were significantly elevated in TGF-β1-treated HK-2 cells. TGF-β1 also induced inactivation of glycogen synthase kinase-3β (GSK3β), an endogenous inhibitor of Snail. Knockdown of Akt2 using siRNAs or the PI3K inhibitor Ly294002 inhibited TGF-β1-induced phosphorylation of GSK3β and expression of Snail1.
  
  
  CONCLUSIONS
  These findings revealed that knockdown of Akt2 antagonized TGF-β1-induced EMT by inhibiting GSK3β/Snail signaling pathway.
authors: Beijing An Zhen Hospital, Capital Medical University, The Key Laboratory of Remodeling-related Cardiovascular Diseases, Ministry of Education, Institute of Heart Lung and Blood Vessel Diseases, Beijing, China.
authors: Aiping
authors: A
authors: Lan
authors: Yongfen
authors: Y
authors: Qi
authors: Jie
authors: J
authors: Du
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers; D058750:Epithelial-Mesenchymal Transition / Q000502:physiology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000502:physiology*
chemical_list: D017931:DNA Primers; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D053773:Transforming Growth Factor beta1; C494921:AKT2 protein, human; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3