PHOSPHOINOSITIDASE-C BETA-1 ISOFORM EXPRESSION IS MODULATED BY INTERFERON-ALPHA IN BURKITT-LYMPHOMA CELLS

The expression of phosphoinositidase C (PIC) at nuclear and cytoplasmi c level has been revealed in control and interferon treated Burkitt ly mphoma cells by means of western blotting and immunocytochemical analy sis employing specific monoclonal antibodies against beta 1, gamma 1 a nd delta 1 isozymes, Results have indicated that PIC isoform beta 1, m ainly detectable in the nucleus, undergoes transient modifications ear ly after interferon treatment. PIC delta I has been found only at cyto plasmic level, apparently insensitive to interferon treatment, while P IC gamma 1 was scarcely or not detected either in the cytoplasmic or i n the nuclear compartment. These results suggest that interferon may e xert its antiproliferative effect activating at least two distinct pat hways of signal transduction, at cytoplasmic and nuclear level, involv ing inositol lipid cycle mainly in the nucleus by modulation of PIC be ta 1 expression.