PHYTOHEMAGGLUTININ INDUCES RAPID DEGRADATION OF PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE AND TRANSIENT ACCUMULATION OF PHOSPHATIDIC-ACID AND DIACYLGLYCEROL IN A HUMAN T-LYMPHOBLASTOID CELL-LINE, CCRF-CEM

  • 1 January 1983
    • journal article
    • research article
    • Vol. 754  (3) , 305-314
Abstract
The human T lymphoblastoid cell line designated CCRF-CEM responds to phytohemagglutinin with a 3.7-fold enhancement of the 32PO4 incorporation into phosphatidylinositol. In myo-[2-3H]inositol-prelabeled CCRF-CEM cells, phytohemagglutinin induced a 3.3-fold accumulation of myo[2-3H]inositol phosphate during 15 min incubation at 37.degree. C in the presence of 5 mM LiCl. Since Li+ is a potent inhibitor of myo-inositol-1-phosphatase, the results indicate that phytohemagglutinin induces the hydrolysis of inositol lipids in CCRF-CEM cells. In 32PO4-prelabeled CCRF-CEM cells, phytohemagglutinin induced a breakdown of 28% of [32P]phosphatidylinositol 4,5-bisphosphate 40-60 s after the stimulation. The decrease of [32P]phosphatidylinositol 4,5-bisphosphate was found as early as 10 s after the stimulation. This decrease was followed by an increased 32P-labeling of phosphatidic acid. In [2-3H]glycerol-prelabeled CCRF-CEM cells, phytohemagglutinin induced a transient accumulation of [3H]phosphatidic acid and [3H]diacylglcerol. The amount of [3H]phosphatidic acid in the stimulated cells was 3.7 times the control value at 2 min after the stimulation, whereas the amount of [3H]diacylglycerol in the stimulated cells was 1.5 times the control value at 5 min after the stimulation. In [3H8]arachidonate-prelabeled CCRF-CEM cells, phytohemagglutinin induced a transient accumulation of [3H]phosphatidic acid; the amount was 2.5 times the control value at 2 min after the stimulation. Quinacrine (1 mM) caused 41% reduction in the amount of [3H]phosphatidic acid accumulated by the stimulation in [2-3H]glycerol-prelabeled cells. Stimulation in a Ca2+-free saline containing 1 mM EGTA [ethyleneglycol bis-[.beta.-aminoethylether]-N,N''-tetraacetic acid] caused 53% reduction in the amount of [3H]phosphatidic acid accumulated by the stimulation. A human T lymphoblastoid cell line, CCRF-CEM, apparently responds to phytohemagglutinin with a rapid turnover of inositol lipids.