The role of dystroglycan in PDGF-BB-dependent migration of activated hepatic stellate cells/myofibroblasts

Abstract

This extracellular matrix contains several basement membrane components including laminin, but its composition changes during liver injury because of the production of extracellular matrix components found in scar tissue. These changes in extracellular matrix composition and in cell-extracellular matrix interactions may play a key role in hepatic stellate cell transdifferentiation. In this communication we used early passages of mouse hepatic stellate cells (activated HSC/ myofibroblasts) to study the platelet-derived growth factor BB (PDGF-BB)-dependent expression and regulation of ␤-dystroglycan and its role in activated HSC/myofibroblast migration. We used Northern and Western analysis to study dystroglycan expression and confocal microscopy to investigate changes in subcellular distribution of the protein. Activated HSC migration was investigated using an in vitro wound-healing assay. PDGF-BB induced significant changes in dystroglycan regulation and subcellular distribution of the protein.Whereas steady-state levels of dystroglycan mRNA remained constant, PDGF-BB increased dystroglycan transcription but shortened the t 1/2 by 50%. Moreover, PDGF-BB changed dystroglycan and ␣5-integrin cellular distribution. Cell migration experiments revealed that PDGF-BB-dependent migration of activated HSC/myofibroblasts was completely blocked by neutralizing antibodies to fibronectin, ␣5-integrin, laminin, and ␤-dystroglycan. Overall, these findings suggest that both laminin and fibronectin and their receptors play a key role in PDGF-BB-induced activated HSC migration.platelet-derived growth factor; HSC activation; fibronectin; laminin; ␣5-integrin HEPATIC STELLATE CELLS (HSC), the main collagen producing cells of the liver, are localized to the perisinusoidal space of Disse and are embedded in a loose connective tissue matrix. This space is devoid of a continuous basement membrane but contains collagens, laminins, and fibronectins (FN) (23). Several liver cell types participate in the production of the extracellular matrix found in the space of Disse although HSC contribute to the production of type IV collagen and laminin (12). Quiescent HSC are characterized by their high content of vitamin A and triglycerides that are the basis for their isolation (28). Upon liver injury, HSC change phenotype and are transformed into myofibroblasts or activated HSC that express multiple growth factor receptors, including platelet-derived growth factor receptor-␤ (PDGF-␤r). Similar events to those observed in vivo during HSC activation can be reproduced when culturing the cells on plastic, collagen, and/or FN-coated culture dishes (21). In contrast with these findings, cultureactivated HSC/myofibroblasts on a laminin-rich gel (Matrigel) stimulates the maintenance of a quiescent state (11) and reverts the myofibroblastic phenotype (31).Dystroglycan (DG) is a laminin-binding protein involved in cell-matrix interaction. It is produced as a large molecularweight protein that upon proteolytic cleavage generates the two DG subunits (␣ and ␤...

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Decoding the role of the nuclear receptor SHP in regulating hepatic stellate cells and liver fibrogenesis

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Culture on a Fragmin/protamine-Coated Plate Suppresses the Collagen Type IαI and TGF-β1 mRNA Expression of Rat Hepatic Stellate RI-T Cells

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