title: Connexin43 Controls the Myofibroblastic Differentiation of Bronchial Fibroblasts from Patients with Asthma.
abstract: Pathologic accumulation of myofibroblasts in asthmatic bronchi is regulated by extrinsic stimuli and by the intrinsic susceptibility of bronchial fibroblasts to transforming growth factor-β (TGF-β). The specific function of gap junctions and connexins in this process has remained unknown. Here, we investigated the role of connexin43 (Cx43) in TGF-β-induced myofibroblastic differentiation of fibroblasts derived from bronchoscopic biopsy specimens of patients with asthma and donors without asthma. Asthmatic fibroblasts expressed considerably higher levels of Cx43 and were more susceptible to TGF-β1-induced myofibroblastic differentiation than were their nonasthmatic counterparts. TGF-β1efficiently up-regulated Cx43 levels and activated the canonical Smad pathway in asthmatic cells. Ectopic Cx43 expression in nonasthmatic (Cx43low) fibroblasts increased their predilection to TGF-β1-induced Smad2 activation and fibroblast-myofibroblast transition. Transient Cx43 silencing in asthmatic (Cx43high) fibroblasts by Cx43 small interfering RNA attenuated the TGF-β1-triggered Smad2 activation and myofibroblast formation. Direct interactions of Smad2 and Cx43 with β-tubulin were demonstrated by co-immunoprecipitation assay, whereas the sensitivity of these interactions to TGF-β1signaling was confirmed by Förster Resonance Energy Transfer analyses. Furthermore, inhibition of the TGF-β1/Smad pathway attenuated TGF-β1-triggered Cx43 up-regulation and myofibroblast differentiation of asthmatic fibroblasts. Chemical inhibition of gap junctional intercellular communication with 18 α-glycyrrhetinic acid did not affect the initiation of fibroblast-myofibroblast transition in asthmatic fibroblasts but interfered with the maintenance of their myofibroblastic phenotype. Collectively, our data identified Cx43 as a new player in the feedback mechanism regulating TGF-β1/Smad-dependent differentiation of bronchial fibroblasts. Thus, our observations point to Cx43 as a novel profibrotic factor in asthma progression.
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Milena
authors.initials: M
authors.lastname: Paw
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Izabela
authors.initials: I
authors.lastname: Borek
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Dawid
authors.initials: D
authors.lastname: Wnuk
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Damian
authors.initials: D
authors.lastname: Ryszawy
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Piwowarczyk
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Kmiotek
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.|2 Department of Medicine, Jagiellonian University Medical School, Kraków, Poland.
authors.forename: Katarzyna A
authors.initials: KA
authors.lastname: Wójcik-Pszczoła
authors.affiliation: 4 Center for Molecular Cardiology, University of Zurich, Zurich, Switzerland and.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Pierzchalska
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Madeja
authors.affiliation: 2 Department of Medicine, Jagiellonian University Medical School, Kraków, Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Sanak
authors.affiliation: 3 Department of Food Biotechnology, Faculty of Food Technology, University of Agriculture, Kraków, Poland.|5 Department of Clinical Immunology, Institute of Pediatrics, Faculty of Medicine, Jagiellonian University Medical College, Kraków, Poland.
authors.forename: Przemysław
authors.initials: P
authors.lastname: Błyszczuk
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Marta
authors.initials: M
authors.lastname: Michalik
authors.affiliation: 1 Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
authors.forename: Jarosław
authors.initials: J
authors.lastname: Czyż
mesh_terms: D000328:Adult; D001249:Asthma / Q000378:metabolism* / Q000473:pathology*; D001980:Bronchi / Q000473:pathology*; D002454:Cell Differentiation / Q000187:drug effects; D018031:Connexin 43 / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D058628:Myofibroblasts / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D010641:Phenotype; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D000099151:MAP Kinase Kinase Kinase 7
chemical_list: D018031:Connexin 43; D048049:Extracellular Signal-Regulated MAP Kinases; D020930:MAP Kinase Kinase Kinases; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D000099151:MAP Kinase Kinase Kinase 7
keywords: Smad2; bronchial asthma; connexin43; myofibroblastic differentiation; transforming growth factor-β