Fibronectin observed in the nuclear matrix of HeLa tumour cells

We have investigated the intracellular distribution of insoluble fibronectin in HeLa tumour cells. By indirect immunofluorescence microscopy fibronectin was detected in the nuclear region, but not in the region of the cell surface. Isolated nuclei and isolated nuclear matrices also stained for fibronectin. By quantitative enzyme-linked immunosorbent assay (ELISA), fibronectin was found almost exclusively in the subcellular fraction of isolated nuclear matrices. Using immunoblotting techniques fibronectin was detected in nuclear matrices isolated from cells grown in standard and in fibronectin-depleted medium. The data demonstrate that fibronectin in HeLa tumour cells is preferentially associated with the nuclear matrix.