title: Hypoxia-inducible factor-1alpha and MAPK co-regulate activation of hepatic stellate cells upon hypoxia stimulation.
abstract: BACKGROUND
  Hepatic stellate cell (HSC) plays a key role in pathogenesis of liver fibrosis. During liver injury, hypoxia in local micro-environment is inevitable. Hif-1α is the key transcriptional regulation factor that induces cell's adaptive responses to hypoxia. Recently, it was reported that MAPK is involved in regulation of Hif-1α activity.
  
  
  OBJECTIVE
  To explore whether Hif-1α regulates HSC activation upon hypoxia, and whether MAPK affects Hif-1α-regulated signaling cascades, thus providing new targets for preventing liver fibrosis.
  
  
  METHODS
  Hif-1α expression in livers of Schistosomajaponicum infected BALB/c mice was detected with western blot and immunohistochemistry. A rat cell line of HSC, HSC-T6, was cultured in 1% oxygen. HSC activation, including F-actin reorganization, increase of vimentin and α-SMA, was detected with western blot or immunocytochemistry. Cells were transfected with specific siRNA to Hif-1α, expression of activation markers, transcription of fibrosis-promoting cytokines, secretion of collagen I were detected with western blot, Real Time PCR and ELISA. Lysate from HSC-T6 cells pretreated with PD98059, a specific MEK1 pharmacological inhibitor, was subjected to detect Hif-1α ubiquitination and nuclear translocation with western blot and immunoprecipitation.
  
  
  CONCLUSIONS
  Hif-1α apparently increased in liver tissues of Schistosomajaponicum infected mice. 1% O2 induced F-actin reorganization, increase of Hif-1α, vimentin and α-SMA in HSC-T6 cells. Hif-1α Knockdown inhibited HSC-T6 activation, transcription of IL-6, TGF-β and CTGF and secretion of collagen I from HSC-T6 cells upon hypoxia. Inhibition of MAPK phosphorylation enhanced Hif-1α ubiquitination, and inhibited Hif-1α translocation into nucleus. Conclusively, Hif-1α and MAPK participate in HSC activation upon hypoxia.
authors.affiliation: Department of Pathogen Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, PR China.
authors.forename: Yueqin
authors.initials: Y
authors.lastname: Wang
authors.forename: Yimin
authors.initials: Y
authors.lastname: Huang
authors.forename: Fei
authors.initials: F
authors.lastname: Guan
authors.forename: Yan
authors.initials: Y
authors.lastname: Xiao
authors.forename: Jing
authors.initials: J
authors.lastname: Deng
authors.forename: Huoying
authors.initials: H
authors.lastname: Chen
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Chen
authors.forename: Jianrong
authors.initials: J
authors.lastname: Li
authors.forename: Hanju
authors.initials: H
authors.lastname: Huang
authors.forename: Chunwei
authors.initials: C
authors.lastname: Shi
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015687:Cell Hypoxia; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D024042:Collagen Type I / Q000378:metabolism; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D055166:Hepatic Stellate Cells / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000378:metabolism / Q000469:parasitology; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D021381:Protein Transport; D051381:Rats; D012549:Schistosoma japonicum; D012554:Schistosomiasis japonica / Q000378:metabolism; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination; D014746:Vimentin / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D024042:Collagen Type I; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D015850:Interleukin-6; D016212:Transforming Growth Factor beta; D014746:Vimentin; D055513:Connective Tissue Growth Factor; D020928:Mitogen-Activated Protein Kinases
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