TRANSFECTED SAOS-2 CELLS OVEREXPRESSING PHOSPHOINOSITIDASE-C BETA(1) ISOFORM ACCUMULATE IT WITHIN THE NUCLEUS

The subcellular partitioning of the phosphoinositidase C (PIC) isoform s involved in signal transduction, with the selective localization of the PIC beta(1) isoform in the nucleus, represents a crucial aspect of the complex mechanism of cell response to agonists. In order to furth er elucidate this phenomenon, we utilized human osteosarcoma Saos-2 ce lls, transfected with the cDNA for rat PIC beta(1). In the cells overe xpressing this isoform, immunocytochemical analyses at the electron mi croscope level reveal an increased synthesis at the cytoplasm and a si gnificant accumulation within the nucleus of the protein. Interestingl y, the sites of intranuclear localization are, as in wild type cells, the interchromatin domains. These results indicate that the transfecte d cells maintain the capability of accumulating the enzyme within the nucleus and can be considered a model for functional studies on the nu clear signal transduction also in response to specific agonists.