title: Tumour necrosis factor-stimulated gene (TSG)-6 controls epithelial-mesenchymal transition of proximal tubular epithelial cells.
abstract: Progressive renal disease is characterized by accumulation of extracellular matrix in the renal cortex. Proximal tubular cells (PTC) may contribute to disease through a process of epithelial-mesenchymal-transition (EMT): phenotypic change, disruption of the tubular basement membrane and migration into the interstitium. Hyaluronan (HA) synthesis and its extracellular organization by hyaladherins affect cell fate in other systems: this study investigated the role of the hyaladherin, tumour necrosis factor-stimulated gene (TSG)-6, in PTC EMT triggered in vitro by transforming growth factor (TGF)β1. TGFβ1 triggered the loss of PTC epithelial phenotype with 60% decreased expression of E-cadherin and 2-3-fold induction of alpha-smooth muscle actin (α-sma). It also increased the expression of TSG-6, HA-synthase-(HAS)2 and the HA-receptor, CD44, to a peak at 8-12h, remaining elevated thereafter. Immuno-localization of HA demonstrated that unstimulated PTC assembled HA in cables and that treatment with TGFβ1 initiated cable disassembly with formation of dense HA-pericellular coats. Stable knockdown of TSG-6 with short-hairpin-RNA increased E-cadherin and HAS2 expression, produced loose HA-pericellular coats, HA cables were absent and cell migration was slowed. Treatment of transfectants with TGFβ1 did not induce α-sma, alter E-cadherin, pericellular-HA or migration but did induce HAS2. This was dependent on the expression of CD44 and was inhibited by CD44-specific siRNA. In summary, TSG-6 was central to EMT through effects on HA macromolecular structure and through CD44-dependent triggering of cell responses. These findings suggest that controlling the assembly of HA by proximal tubular cells may be a novel approach towards intervention in renal disease.
authors.affiliation: Institute of Nephrology, School of Medicine and Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Heath Park, Cardiff, CF14 4XN, Wales, UK.
authors.forename: Girish
authors.initials: G
authors.lastname: Bommaya
authors.forename: Soma
authors.initials: S
authors.lastname: Meran
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Krupa
authors.forename: Aled Owain
authors.initials: AO
authors.lastname: Phillips
authors.forename: Robert
authors.initials: R
authors.lastname: Steadman
mesh_terms: D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D002465:Cell Movement; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism; D006820:Hyaluronic Acid / Q000096:biosynthesis; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism
chemical_list: C497483:CD44 protein, human; D015820:Cadherins; D015815:Cell Adhesion Molecules; D018960:Hyaluronan Receptors; D034741:RNA, Small Interfering; C508960:TGFB1 protein, human; C072273:TNFAIP6 protein, human; D053773:Transforming Growth Factor beta1; D006820:Hyaluronic Acid