title: β2-microglobulin induces epithelial-mesenchymal transition in human renal proximal tubule epithelial cells in vitro.
abstract: BACKGROUND
  The objective of this study was to investigate the influence of β2-microglobulin (β2-M) on the epithelial-mesenchymal transition (EMT) in renal tubular epithelial cells.
  
  
  METHODS
  A human kidney proximal tubular cell line (HK-2) was used as the proximal tubular cell model. HK-2 cells were exposed to different concentrations of β2-M (5, 10, 25, and 50 μM) for up to 24, 48 and 72 h. The effects of β2-M on cell morphology were observed by phase contrast microscopy, and the possible associated mechanisms were assessed by immunofluorescence staining, western blot, RNA interference, immunoprecipitation, and induced coupled plasma mass spectroscopy.
  
  
  RESULTS
  β2-M induced marked morphological alterations in the HK-2 cells, accompanied by the increased expression of extracellular matrix components and α-smooth muscle actin (α-SMA), vimentin and fibronectin and the reduced expression of E-cadherin. Our results also revealed that β2-M could induce the EMT in the HK-2 cells without significant affecting cell viability. Excess β2-M in the HK-2 cells led to a decrease in iron and an increase in hypoxia inducible factor-1α (HIF-1α), which induced EMT in the HK-2 cells. Additionally, disrupting the function of the β2-M/hemochromatosis (HFE) complex by HFE knockdown was sufficient to reverse β2-M-mediated EMT in the HK-2 cells.
  
  
  CONCLUSIONS
  These findings demonstrate that the activity of β2-M is mediated by the β2-M/HFE complex, which regulates intracellular iron homeostasis and HIF-1α and ultimately induces EMT in HK2 cells.
authors.affiliation: Department of Pediatric Nephrology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, P. R. China. njaiqing@njmu.edu.cn.
authors.forename: Aiqing
authors.initials: A
authors.lastname: Zhang
authors.affiliation: Division of Nephrology, Huashan Hospital and Institute of Nephrology, Fudan University, Shanghai, 200040, P.R. China. wangbinhewei@126.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.affiliation: Department of Nephrology, the Third Affiliated Hospital of Soochow University, Changzhou, 210003, China. yangmin79@sina.com.
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Pediatric Nephrology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, P. R. China. pjr1951@163.com.
authors.forename: Huimin
authors.initials: H
authors.lastname: Shi
authors.affiliation: Department of Pediatric Nephrology, the Second Affiliated Hospital of Nanjing Medical University, Nanjing, 210011, P. R. China. weihuagan@njmu.edu.cn.
authors.forename: Weihua
authors.initials: W
authors.lastname: Gan
mesh_terms: D000199:Actins / Q000187:drug effects / Q000378:metabolism; D015153:Blotting, Western; D015820:Cadherins / Q000187:drug effects / Q000378:metabolism; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D005353:Fibronectins / Q000187:drug effects / Q000378:metabolism; D055785:Gene Knockdown Techniques; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000187:drug effects / Q000378:metabolism; D047468:Immunoprecipitation; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism; D008858:Microscopy, Phase-Contrast; D034622:RNA Interference; D014746:Vimentin / Q000187:drug effects / Q000378:metabolism; D001613:beta 2-Microglobulin / Q000494:pharmacology*
chemical_list: C541116:ACTA2 protein, human; D000199:Actins; D015820:Cadherins; D005353:Fibronectins; C103673:HFE protein, human; C497442:HIF1A protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008565:Membrane Proteins; D014746:Vimentin; D001613:beta 2-Microglobulin