Plectin is concentrated at intercellular junctions and at the nuclear surface in morphologically differentiated rat Sertoli cells

Intermediate filaments in Sertoli cells have a well-defined pattern of dist ribution. They form a basally situated perinuclear network from which filam ents extend peripherally to adhesion plaques at the plasma membrane and to sites of codistribution with other major elements of the cytoskeleton, part icularly with microtubules, Although the general pattern of intermediate fi lament distribution is known, the molecular components involved with linkin g the filaments to organelles and attachment plaques in these cells have no t been identified. One candidate for such a linking element is plectin. In this study we test for the presence of, and determine the distribution of, plectin in Sertoli cells of the rat testis. Fixed frozen sections and fixed epithelial fragments of rat testis were pro bed far plectin and vimentin using antibodies; Tissue-was evaluated using s tandard fluorescence microscopy and confocal microscopy. Plectin in Sertoli cells was concentrated in a narrow zone surrounding the nucleus, and at focal sites, presumably desmosome-like plaques, at interfac es with adjacent cells. Plectin was also concentrated at sites where? inter mediate filament bundles project into specialized actin-filament containing plaques at sites of attachment to elongate spermatids. Plectin in Sertoli cells is concentrated at the nuclear surface and in junc tion plaques associated with the plasma membrane. The pattern of distributi on is consistent with plectin being involved with linking intermediate fila ments centrally (basally) to; the nucleus and peripherally to intercellular attachment sites. Anat Rec 254:418-428, 1999. (C) 1999 Wiley-Liss, Inc.