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During embryonic development, cell movement is orchestrated by a multitude of attractants and repellents. Chemoattractants applied as a gradient, such as cAMP with Dictyostelium discoideum or fMLP with neutrophils, induce the activation of phospholipase C ( PLC) and phosphoinositide 3 (PI3)-kinase at the front of the cell, leading to the localized depletion of phosphatidylinositol 4,5- bisphosphate (PI[4,5]P-2) and the accumulation of phosphatidylinositol- 3,4,5-trisphosphate (PI[3,4,5]P-3). Using D. discoideum, we show that chemorepellent cAMP analogues induce localized inhibition of PLC, thereby reversing the polarity of PI( 4,5)P-2. This leads to the accumulation of PI( 3,4,5) P3 at the rear of the cell, and chemotaxis occurs away from the source. We conclude that a PLC polarity switch controls the response to attractants and repellents. |
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