title: Tumor Necrosis Factor-stimulated Gene 6 (TSG-6)-mediated Interactions with the Inter-α-inhibitor Heavy Chain 5 Facilitate Tumor Growth Factor β1 (TGFβ1)-dependent Fibroblast to Myofibroblast Differentiation.
abstract: Fibroblasts are central to wound healing and fibrosis through TGFβ1-triggered differentiation into contractile, α-smooth muscle actin (α-SMA)-positive myofibroblasts. This is mediated by accumulation of a pericellular matrix of hyaluronan (HA) and the HA-dependent co-localization of CD44 with the epidermal growth factor receptor (EGFR). Interactions of HA with hyaladherins, such as inter-α-inhibitor (IαI) and tumor necrosis factor-stimulated gene-6 (TSG-6), are also essential for differentiation. This study investigated the mechanisms involved. TSG-6 and α-SMA had different kinetics of induction by TGFβ1, with TSG-6 peaking before α-SMA Si CD44 or EGFR inhibition prevented differentiation but had no effect on TSG-6 expression. TSG-6 was essential for differentiation, and mAb A38 (preventing IαI heavy chain (HC) transfer), HA-oligosaccharides, cobalt, or Si bikunin prevented TSG-6 activity, preventing differentiation. A38 also prevented the EGFR/CD44 association. This suggested that TSG-6/IαI HC interaction was necessary for the effect of TSG-6 and that HC stabilization of HA initiated the CD44/EGFR association. The newly described HC5 was shown to be the principal HC expressed, and its cell surface expression was prevented by siRNA inhibition of TSG-6 or bikunin. HC5 was released by hyaluronidase treatment, confirming its association with cell surface HA. Finally, HC5 knockdown by siRNA confirmed its role in myofibroblast differentiation. The current study describes a novel mechanism linking the TSG-6 transfer of the newly described HC5 to the HA-dependent control of cell phenotype. The interaction of HC5 with cell surface HA was essential for TGFβ1-dependent differentiation of fibroblasts to myofibroblasts, highlighting its importance as a novel potential therapeutic target.
authors.affiliation: From the Department of Nephrology, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Heath Park, Cardiff CF14 4XN, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Martin
authors.affiliation: From the Department of Nephrology, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Heath Park, Cardiff CF14 4XN, United Kingdom.
authors.forename: Adam
authors.initials: A
authors.lastname: Midgley
authors.affiliation: From the Department of Nephrology, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Heath Park, Cardiff CF14 4XN, United Kingdom.
authors.forename: Soma
authors.initials: S
authors.lastname: Meran
authors.affiliation: From the Department of Nephrology, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Heath Park, Cardiff CF14 4XN, United Kingdom.
authors.forename: Emma
authors.initials: E
authors.lastname: Woods
authors.affiliation: From the Department of Nephrology, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Heath Park, Cardiff CF14 4XN, United Kingdom.
authors.forename: Timothy
authors.initials: T
authors.lastname: Bowen
authors.affiliation: From the Department of Nephrology, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Heath Park, Cardiff CF14 4XN, United Kingdom.
authors.forename: Aled O
authors.initials: AO
authors.lastname: Phillips
authors.affiliation: From the Department of Nephrology, Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Heath Park, Cardiff CF14 4XN, United Kingdom steadmanr@cf.ac.uk.
authors.forename: Robert
authors.initials: R
authors.lastname: Steadman
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000510:Alpha-Globulins / Q000494:pharmacology; D058846:Antibodies, Monoclonal, Murine-Derived / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018960:Hyaluronan Receptors / Q000494:pharmacology; D058628:Myofibroblasts / Q000166:cytology / Q000378:metabolism*; D053491:Proteinase Inhibitory Proteins, Secretory / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D000510:Alpha-Globulins; D058846:Antibodies, Monoclonal, Murine-Derived; C497483:CD44 protein, human; D015815:Cell Adhesion Molecules; D018960:Hyaluronan Receptors; C482680:ITIH5 protein, human; D053491:Proteinase Inhibitory Proteins, Secretory; C508960:TGFB1 protein, human; C072273:TNFAIP6 protein, human; D053773:Transforming Growth Factor beta1; C016001:alpha-1-microglobulin; C512478:EGFR protein, human; D066246:ErbB Receptors
keywords: fibroblast; fibrosis; hyaluronan; myofibroblast; transforming growth factor beta (TGF-B); tumor necrosis factor gene 6