title: Down-regulation of USP13 mediates phenotype transformation of fibroblasts in idiopathic pulmonary fibrosis.
abstract: BACKGROUND
  Idiopathic pulmonary fibrosis (IPF) is a fatal disease characterized by fibroblastic foci and progressive scarring of the pulmonary parenchyma. IPF fibroblasts display increased proliferation and enhanced migration and invasion, analogous to cancer cells. This transformation-like phenotype of fibroblasts plays an important role in the development of pulmonary fibrosis, but the mechanism for this is not well understood.
  
  
  METHODS
  In this study, we compared gene expression profiles in fibrotic lung tissues from IPF patients and normal lung tissues from patients with primary spontaneous pneumothorax using a cDNA microarray to examine the mechanisms involved in the pathogenesis of IPF. In a cDNA microarray, we found that USP13 was decreased in lung tissues from patients with IPF, which was further confirmed by results from immunohistochemistry and western blot assays. Then, we used RNA interference in MRC-5 cells to inhibit USP13 and evaluated its effects by western blot, real-time RT-PCR, bromodeoxyuridine incorporation, and transwell assays. We also used co-immunoprecipitation and immunofluorescence staining to identify the correlation between USP13 and PTEN in IPF.
  
  
  RESULTS
  USP13 expression levels were markedly reduced in fibroblastic foci and primary IPF fibroblast lines. The depletion of USP13 resulted in the transformation of fibroblasts into an aggressive phenotype with enhanced proliferative, migratory, and invasive capacities. Additionally, USP13 interacted with PTEN and mediated PTEN ubiquitination and degradation in lung fibroblasts.
  
  
  CONCLUSIONS
  Down-regulation of USP13 mediates PTEN protein loss and fibroblast phenotypic change, and thereby plays a crucial role in IPF pathogenesis.
authors.affiliation: Department of Respiratory and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital-Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, P.R. China. jing_geng@foxmail.com.
authors.forename: Jing
authors.initials: J
authors.lastname: Geng
authors.affiliation: Department of Medical Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, P.R. China. xxhuang@126.com.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Huang
authors.affiliation: Department of Medical Research, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, 100020, P.R. China. leeeying2013@hotmail.com.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Respiratory and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital-Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, P.R. China. xuxuefeng2001789@163.com.|National Clinical Research Centre for Respiratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China. xuxuefeng2001789@163.com.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Respiratory and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital-Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, P.R. China. lishuhong0925@126.com.
authors.forename: Shuhong
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Respiratory and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital-Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, P.R. China. dingr1121@sina.cn.
authors.forename: Dingyuan
authors.initials: D
authors.lastname: Jiang
authors.affiliation: Department of Medicine Pulmonary Division and Women's Guild Lung Institute, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, USA. Carol.liang@cshs.org.
authors.forename: Jiurong
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Medicine Pulmonary Division and Women's Guild Lung Institute, Cedars-Sinai Medical Center, Los Angeles, CA, 90048, USA. dianhua.jiang@cshs.org.
authors.forename: Dianhua
authors.initials: D
authors.lastname: Jiang
authors.affiliation: Department of Respiratory and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital-Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, P.R. China. cyh-birm@263.net.|National Clinical Research Centre for Respiratory Medicine, Beijing Hospital, Beijing, 100730, P.R. China. cyh-birm@263.net.|China-Japan Friendship Hospital, Beijing, 100029, P.R. China. cyh-birm@263.net.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Respiratory and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital-Beijing Institute of Respiratory Medicine, Capital Medical University, Beijing, 100020, P.R. China. daihuaping@ccmu.edu.cn.|China-Japan Friendship Hospital, Beijing, 100029, P.R. China. daihuaping@ccmu.edu.cn.
authors.forename: Huaping
authors.initials: H
authors.lastname: Dai
mesh_terms: D000328:Adult; D015153:Blotting, Western; D016022:Case-Control Studies; D002454:Cell Differentiation; D002460:Cell Line; D002465:Cell Movement; D049109:Cell Proliferation; D015536:Down-Regulation; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition; D005347:Fibroblasts / Q000201:enzymology* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D047468:Immunoprecipitation; D008168:Lung / Q000201:enzymology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D010641:Phenotype; D059748:Proteolysis; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D064570:Ubiquitin-Specific Proteases; D054875:Ubiquitination
chemical_list: D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D010450:Endopeptidases; C561638:USP13 protein, human; D064570:Ubiquitin-Specific Proteases