Antigen receptor-mediated regulation of sustained polyphosphoinositide turnover in a human T cell line. Evidence for a receptor-regulated pathway for production of phosphatidylinositol 4,5-bisphosphate

Journal Article · Sun Apr 15 04:00:00 EDT 1990 · Journal of Biological Chemistry; (USA)

OSTI ID:6896867

Inokuchi, S; Imboden, J B ^[1]

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1. Univ. of California, San Francisco (USA)

Stimulation of the human T cell line, Jurkat, by the addition of monoclonal antibodies reactive with the T cell antigen receptor complex (CD3/Ti) leads to sustained increases in levels of inositol 1,4,5-trisphosphate. To investigate the possibility that the production of polyphosphoinositides is regulated during CD3/Ti stimulation, we studied Jurkat cells whose inositol phospholipids had been labeled to steady state with (3H)inositol, as well as Jurkat cells during nonequilibrium labeling with (32P)orthophosphate. The addition of CD3 monoclonal antibodies led to a 4-5-fold increase in (3H)inositol trisphosphate that was sustained for greater than 20 min. Within 60 s of CD3/Ti stimulation, (3H) phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and (3H)phosphatidylinositol 4-phosphate (PtdIns4P) decreased by 65 and 35%, respectively. This change in (3H)PtdIns(4,5)P2 persisted for greater than 20 min. The decrease in (3H)PtdIns4P, however, was transient, and, after 5 min, the levels of (3H)PtdIns4P were comparable in stimulated and unstimulated cells. To examine the rate of flux through inositol phospholipids, we measured the CD3/Ti-stimulated changes in the ratio, 32P cpm/3H cpm, in each inositol phospholipid. CD3/Ti stimulation led to accelerated fluxes through PtdIns(4,5)P2 and phosphatidylinositol (PtdIns) that were maintained for greater than 20 min. After the initial 30 s, however, there was no detectable effect of anti-CD3 on flux through Ptsins4p. This observation suggested that, during CD3/Ti stimulation, production of PtdIns(4,5)P2 from PtdIns might occur via a small pool of PtdIns4P with a very high turnover. The existence of such a pool was established by determining that, in stimulated cells, the 32P-specific activity of the 1-position phosphate of PtdIns(4,5)P2 was 8-10-fold that of PtdIns4P.

• OSTI ID: 6896867
• Journal Information: Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 265:11; ISSN 0021-9258; ISSN JBCHA
• Country of Publication: United States
• Language: English

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59 BASIC BIOLOGICAL SCIENCES
ANIMAL CELLS
ANIMALS
ANTIGENS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL MATERIALS
BIOLOGICAL PATHWAYS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBOHYDRATES
CELL DIFFERENTIATION
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ESTERS
HOMEOSTASIS
HYDROGEN COMPOUNDS
INOSITOL
INOSITOLS
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LEUKOCYTES
LIGHT NUCLEI
LIPIDS
LYMPHOCYTES
MAMMALS
MAN
MATERIALS
MEMBRANE PROTEINS
METABOLISM
MONOSACCHARIDES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHOLIPIDS
PHOSPHORUS 32
PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PRIMATES
PROTEINS
RADIOISOTOPES
REACTION KINETICS
RECEPTORS
SACCHARIDES
SOMATIC CELLS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
VERTEBRATES