Sensitization of Dictyostelium chemotaxis by phosphoinositide-3-kinase-mediated self-organizing signalling patches

M. Postma, J. Roelofs, J. Goedhart, H.M. Loovers, A.J.W.G. Visser, P.J.M. van Haastert

Research output: Contribution to journalArticleAcademicpeer-review

78 Citations (Scopus)

Abstract

The leading edge of Dictyostelium cells in chemoattractant gradients can be visualized using green fluorescent protein (GFP) tagged to the pleckstrin-homology (PH) domain of cytosolic regulator of adenylyl cyclase (CRAC), which presumable binds phosphatidylinositol-(3,4,5)triphosphate [PtdIns(3,4,5)P3]. Uniform cyclic AMP (cAMP) concentrations induce persistent translocation of PHCrac-GFP from the cytosol to multiple patches, which are similar to the single patch of PHCrac-GFP at the leading edge in a cAMP gradient. We show that cAMP determines the probability of patch formation (half-maximal effect at 0.5 nM cAMP) but not the size, lifetime or intensity of patches, indicating that patches are self-organizing structures. A pseudopod is extended from the area of the cell with a PHCrac-GFP patch at about 10 seconds after patch formation. Cells treated with the F-actin inhibitor latrunculin A are round without pseudopodia; uniform cAMP still induces localized patches of PHCrac-GFP. Inhibition of phosphoinositide-3-kinase (PI3K) activity with LY294002 inhibits PHCrac-GFP patches and inhibits chemotaxis towards nanomolar cAMP but has no effect at higher cAMP concentrations. Thus, very low cAMP concentrations induce self-organizing PHCrac-GFP patches that serve as a spatial cue for pseudopod formation, which enhances the sensitivity and amplitude of chemotactic movement
Original languageEnglish
Pages (from-to)2925-2935
JournalJournal of Cell Science
Volume117
Issue number14
DOIs
Publication statusPublished - 2004

Keywords

  • living cells
  • chemoattractant receptor
  • neutrophil chemotaxis
  • pi 3-kinase
  • activation
  • polarity
  • protein
  • gradient
  • gamma
  • roles

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