A rapid stimulation of phosphatidylinositol metabolism in rabbit leukocytes by pseudomonal leukocidin

We show that pseudomonal leukocidin induced a rapid metabolic change of PI (PI

Toshiya Hirayama; Iwao Kato


Scholarcy highlights

  • Rapid phosphatidylinositol turnover in response to stimulation by hormones or by neurotransmitters is accompanied by an increase in the cytosolic for utilization ofCa2+ as their intracellular second messenger by way of Ca’+-dependent protein phosphorylation in a similar manner to glycogen metabolism, smooth-muscle contraction, and ion transport
  • By two-dimensional thin layer chromatography for phospholipid analysis of rabbit leukocytes, the incorporation of 32Pi into Phosphatidic acid was remarkably stimulated in leukocytes exposed to pseudomonal leukocidin for 5 min, compared with non-treated cells
  • The effect of pseudomonal leukocidin on the 32Pi-incorporation was apparently manifested in PA, DPI, and TPI
  • The treatment of leukocyte with leukocidin induced early formations of DPI and TPI which reached each maximum at 3 min accompanying rapid decreases of both phospholipids
  • Labelling of PA in leukocytes exposed to leukocidin became maximal at 5 min and diminished slowly accompanying a gradual increase in labelling of PI
  • DPI, TPI and PA over 60 s following addition of ed. {3~]Gly~erol purse-chase experiments demonstrated that the radioactivities of polyphosphoinositides as well as PI declined to a similar extent without the ensuring increase in radioactivity. These results indicate that the increase of radioactivity of PA in leukocidin-treated leukocytes is a reflection of rapid metabolic change of PI concerning the breakdown of polyphosphoinositides, but not an enhancement of de novo synthesis of PA
  • We concluded that the accumulation of Phosphatidic acid and the breakdown of polyphosphoinositides in leukocidin-treated leukocytes might cause mobilization of Ca2+ from intracellular compartments and extracellular medium

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