Perinuclear distribution of plectin characterizes visceral epithelial cells of rat glomeruli

Plectin is an intermediate-filament-associated protein identified over a wide range of tissue and cell types. The distribution of this protein in glomerular visceral epithelial cells (VECs) during the differentiation and growth of rat kidneys was studied in comparison with that of vimentin. By immunofluorescence microscopy, preferential localization of these two cytomatrix elements was different, although both were observed in the cell body and primary processes of VECs. Strong staining of plectin was always found in the perinuclear region of the VEC body in kidneys of young and adult rat, but vimentin stained distinctly only in the primary processes of young rats yet in both cell bodies and primary processes of the adults. This perinuclear staining was unique to VECs, that is, was absent from other cells. In the neonatal kidney, plectin staining during differentiation of VECs changed from weak and diffuse throughout the cytoplasm in the S-shaped body to prominently perinuclear in the maturing stage. However, after the differentiation of VECs, the staining intensity of plectin did not change further. In contrast, that of vimentin increased conspicuously in parallel with the growth of VECs rather than at differentiation. After a long period of culture and during aminonucleoside nephrosis, situations when VECs lose differentiated phenotypes, most of the cells had no perinuclear plectin. These findings indicate that the perinuclear distribution of plectin may play an important role in the differentiation of VECs.