title: Role of Sonic Hedgehog in idiopathic pulmonary fibrosis.
abstract: Idiopathic pulmonary fibrosis (IPF) is a progressive and lethal disease of unknown etiology and uncertain pathogenic mechanisms. Recent studies indicate that the pathogenesis of the disease may involve the abnormal expression of certain developmental pathways. Here we evaluated the expression of Sonic Hedgehog (SHH), Patched-1, Smoothened, and transcription factors glioma-associated oncogene homolog (GLI)1 and GLI2 by RT-PCR, as well as their localization in IPF and normal lungs by immunohistochemistry. The effects of SHH on fibroblast proliferation, migration, collagen and fibronectin production, and apoptosis were analyzed by WST-1, Boyden chamber chemotaxis, RT-PCR, Sircol, and annexin V-propidium iodide binding assays, respectively. Our results showed that all the main components of the Sonic signaling pathway were overexpressed in IPF lungs. With the exception of Smoothened, they were also upregulated in IPF fibroblasts. SHH and GLI2 localized to epithelial cells, whereas Patched-1, Smoothened, and GLI1 were observed mainly in fibroblasts and inflammatory cells. No staining was detected in normal lungs. Recombinant SHH increased fibroblast proliferation (P < 0.05), collagen synthesis, (2.5 ± 0.2 vs. 4.5 ± 1.0 μg of collagen/ml; P < 0.05), fibronectin expression (2-3-fold over control), and migration (190.3 ± 12.4% over control, P < 0.05). No effect was observed on α-smooth muscle actin expression. SHH protected lung fibroblasts from TNF-α/IFN-γ/Fas-induced apoptosis (14.5 ± 3.2% vs. 37.3 ± 7.2%, P < 0.0001). This protection was accompanied by modifications in several apoptosis-related proteins, including increased expression of X-linked inhibitor of apoptosis. These findings indicate that the SHH pathway is activated in IPF lungs and that SHH may contribute to IPF pathogenesis by increasing the proliferation, migration, extracellular matrix production, and survival of fibroblasts.
authors.affiliation: Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico.
authors.forename: Alfredo Lozano
authors.initials: AL
authors.lastname: Bolaños
authors.forename: Criselda Mendoza
authors.initials: CM
authors.lastname: Milla
authors.forename: José Cisneros
authors.initials: JC
authors.lastname: Lira
authors.forename: Remedios
authors.initials: R
authors.lastname: Ramírez
authors.forename: Marco
authors.initials: M
authors.lastname: Checa
authors.forename: Lourdes
authors.initials: L
authors.lastname: Barrera
authors.forename: Jorge
authors.initials: J
authors.lastname: García-Alvarez
authors.forename: Verónica
authors.initials: V
authors.lastname: Carbajal
authors.forename: Carina
authors.initials: C
authors.lastname: Becerril
authors.forename: Miguel
authors.initials: M
authors.lastname: Gaxiola
authors.forename: Annie
authors.initials: A
authors.lastname: Pardo
authors.forename: Moisés
authors.initials: M
authors.lastname: Selman
mesh_terms: D017209:Apoptosis; D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism / Q000502:physiology; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D054990:Idiopathic Pulmonary Fibrosis / Q000378:metabolism* / Q000473:pathology; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism; D008168:Lung / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000072086:Smoothened Receptor; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D000071676:Zinc Finger Protein GLI1; D000075746:Zinc Finger Protein Gli2
chemical_list: D024042:Collagen Type I; D005353:Fibronectins; C400551:GLI1 protein, human; C082593:GLI2 protein, human; D053823:Hedgehog Proteins; D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; C509239:SHH protein, human; C491023:SMO protein, human; D000072086:Smoothened Receptor; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1; D000075746:Zinc Finger Protein Gli2