COLOCALIZATION OF 3 TYPES OF INTERMEDIATE FILAMENT PROTEINS IN PERISINUSOIDAL STELLATE CELLS - GLIAL FIBRILLARY ACIDIC PROTEIN AS A NEW CELLULAR MARKER

The presence and the colocalization of the three intermediate filament proteins, glial fibrillary acidic protein (GFAP) and the marker of me senchymal liver cells, vimentin, were studied by an immunofluorescence double-labeling technique in cultures of isolated rat perisinusoidal stellate cells (PSC) and hepatocytes, in cocultures of isolated PSC an d hepatocytes as well as in cryostat sections of rat liver. GFAP and v imentin immunoreactivities were localized in cultured PSC which were i dentified by the presence of the cellular marker desmin, another inter mediate filament protein, or the stellate morphology to be seen after staining for one of three intermediate filament proteins. Both GFAP an d vimentin were strongly expressed in the perinuclear region and the c ell processes of cultured PSC. Staining for GFAP highly coincided with that for vimentin or desmin in cultured PSC and with that for vimenti n in the liver sections, Desmin-positive cells were always also GFAP-p ositive. However, of the GFAP-positive cells only an estimated 50 % we re found desmin-positive, The coexpression of desmin and GFAP in the s ame cells appear to be unique, since apparently it has not been previo usly reported for any other cell type, Almost all of the vimentin-posi tive cells in hepatocyte culture were also expressing GFAP, Since desm in was not found in all of the cultured cells with PSC morphology, GFA P is suggested as a more reliable marker for PSC than desmin.