Dystroglycan expression in hepatic stellate cells: role in liver fibrosis.
Dystroglycan is a membrane component of the dystrophin-glycoprotein transmembrane complex. Its expression is required for the spatial organization of laminin on the cell surface and for basement membrane assembly. In view of the constitution of a perisinusoidal basement membrane during liver fibrosis, we studied dystroglycan expression in liver fibrosis. Dystroglycan mRNA and protein expression were investigated by immunofluorescence, Western blot, and quantitative RT-PCR (TaqMan) in normal human and rat liver and in isolated rat hepatic stellate cells. On Western blot, a 43-kd band corresponding to beta-dystroglycan was observed in protein extracted from normal and fibrotic human and rat livers. The specific 43-kd protein was also detected in lysates from rat hepatic stellate cells but not from hepatocytes. By immunofluorescence, patchy deposits of beta-dystroglycan were detected on membrane of hepatic stellate cells in culture. On Western blot and quantitative RT-PCR, an up-regulation of beta-dystroglycan was shown during spontaneous activation of hepatic stellate cells in culture. Direct evidence for the role of dystroglycan in laminin-hepatic stellate cell interaction was shown because specific antibody directed against alpha-dystroglycan inhibited partially hepatic stellate cell adhesion on laminin-coated plates. This mechanism was calcium dependent because EDTA inhibited cell/laminin adhesion, an effect reversed by addition of Ca(2+). This study shows that dystroglycan is expressed on the membrane of hepatic stellate cells and is up-regulated during liver fibrosis. Dystroglycan interaction with laminin should be implicated in the concentration of pericellular laminin and in the constitution of a perisinusoidal basement membrane during liver fibrosis.
Bedossa
Pierre
P
Service d'Anatomie Pathologique, Hôpital de Bicêtre, Université Paris Sud, France. pbedossa@teaser.fr
Ferlicot
Sophie
S
Paradis
Valérie
V
Dargère
Delphine
D
Bonvoust
Frank
F
Vidaud
Michel
M
D000818:Animals; D002118:Calcium / Q000378:metabolism; D003239:Connective Tissue Cells / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000096:biosynthesis*; D049030:Dystroglycans; D006801:Humans; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D008103:Liver Cirrhosis / Q000209:etiology / Q000378:metabolism*; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
D003598:Cytoskeletal Proteins; C483081:DAG1 protein, human; D008562:Membrane Glycoproteins; D049030:Dystroglycans; D002118:Calcium