title: The transcription factor GLI2 as a downstream mediator of transforming growth factor-β-induced fibroblast activation in SSc.
abstract: OBJECTIVE
  Hedgehog signalling plays a critical role during the pathogenesis of fibrosis in systemic sclerosis (SSc). Besides canonical hedgehog signalling with smoothened (SMO)-dependent activation of GLI transcription factors, GLI can be activated independently of classical hedgehog ligands and receptors (so-called non-canonical pathways). Here, we aimed to evaluate the role of non-canonical hedgehog signalling in SSc and to test the efficacy of direct GLI inhibitors that target simultaneously canonical and non-canonical hedgehog pathways.
  
  
  METHODS
  The GLI inhibitor GANT-61 was used to inhibit canonical as well as non-canonical hedgehog signalling, while the SMO inhibitor vismodegib was used to selectively target canonical hedgehog signalling. Furthermore, GLI2 was selectively depleted in fibroblasts using the Cre-LoxP system. The effects of pharmacological or genetic of GLI2 on transforming growth factor-β (TGF-β) signalling were analysed in cultured fibroblasts, in bleomycin-induced pulmonary fibrosis and in mice with overexpression of a constitutively active TGF-β receptor I.
  
  
  RESULTS
  TGF-β upregulated GLI2 in a Smad3-dependent manner and induced nuclear accumulation and DNA binding of GLI2. Fibroblast-specific knockout of GLI2 protected mice from TBRact-induced fibrosis. Combined targeting of canonical and non-canonical hedgehog signalling with direct GLI inhibitors exerted more potent antifibrotic effects than selective targeting of canonical hedgehog signalling with SMO inhibitors in experimental dermal and pulmonary fibrosis.
  
  
  CONCLUSIONS
  Our data demonstrate that hedgehog pathways and TGF-β signalling both converge to GLI2 and that GLI2 integrates those signalling to promote tissue fibrosis. These findings may have translational implications as non-selective inhibitors of GLI2 are in clinical use and selective molecules are currently in development.
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Ruifang
authors: R
authors: Liang
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.|Department of Clinical and Experimental Rheumatology, 1st Faculty of Medicine, Institute of Rheumatology, Charles University, Prague, Czech Republic.
authors: Barbora
authors: B
authors: Šumová
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.|Dipartimento Cardiotoracico e Vascolare, Laboratory of Respiratory Cell Biology, University of Pisa, Pisa, Italy.
authors: Cinzia
authors: C
authors: Cordazzo
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Tatjana
authors: T
authors: Mallano
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Yun
authors: Y
authors: Zhang
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Thomas
authors: T
authors: Wohlfahrt
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Clara
authors: C
authors: Dees
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Andreas
authors: A
authors: Ramming
authors: Department of Dermatology, Venereology and Pediatric Dermatology, Medical University of Lublin, Poland.
authors: Dorota
authors: D
authors: Krasowska
authors: Department of Dermatology, Venereology and Pediatric Dermatology, Medical University of Lublin, Poland.
authors: Małgorzata
authors: M
authors: Michalska-Jakubus
authors: Rheumaklinik, University Hospital Zurich, Zurich, Switzerland.
authors: Oliver
authors: O
authors: Distler
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Georg
authors: G
authors: Schett
authors: Department of Clinical and Experimental Rheumatology, 1st Faculty of Medicine, Institute of Rheumatology, Charles University, Prague, Czech Republic.
authors: Ladislav
authors: L
authors: Šenolt
authors: Department of Internal Medicine III and Institute for Clinical Immunology, University of Erlangen-Nuremberg, Erlangen, Germany.
authors: Jörg H W
authors: JH
authors: Distler
mesh_terms: D000328:Adult; D000368:Aged; D000813:Anilides / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics; D055513:Connective Tissue Growth Factor / Q000235:genetics; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005355:Fibrosis; D055786:Gene Knockout Techniques; D053823:Hedgehog Proteins / Q000378:metabolism*; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008875:Middle Aged; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics; D011621:Pteridines / Q000494:pharmacology; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D012595:Scleroderma, Systemic / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D012867:Skin / Q000187:drug effects / Q000473:pathology*; D051900:Smad3 Protein / Q000378:metabolism; D000072086:Smoothened Receptor / Q000037:antagonists & inhibitors; D016212:Transforming Growth Factor beta / Q000378:metabolism* / Q000494:pharmacology; D055815:Young Adult; D000075746:Zinc Finger Protein Gli2
chemical_list: D000813:Anilides; D024042:Collagen Type I; C551027:GANT 61; C000618551:Gli2 protein, mouse; D053823:Hedgehog Proteins; C538724:HhAntag691; D051741:Kruppel-Like Transcription Factors; D017395:Plasminogen Activator Inhibitor 1; D011621:Pteridines; D011725:Pyridines; D011743:Pyrimidines; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D011994:Recombinant Proteins; C511004:SD-208; D051900:Smad3 Protein; D000072086:Smoothened Receptor; D016212:Transforming Growth Factor beta; D000075746:Zinc Finger Protein Gli2; D055513:Connective Tissue Growth Factor; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I
keywords: Fibroblasts; Systemic Sclerosis; Treatment