Spatiotemporal Regulation of Ras Activity Provides Directional Sensing

Sheng Zhang, Pascale G. Charest, Richard A. Firtel

Research output: Contribution to journalArticlepeer-review

88 Scopus citations


Cells' ability to detect and orient themselves in chemoattractant gradients has been the subject of numerous studies, but the underlying molecular mechanisms remain largely unknown [1]. Ras activation is the earliest polarized response to chemoattractant gradients downstream from heterotrimeric G proteins in Dictyostelium, and inhibition of Ras signaling results in directional migration defects [2]. Activated Ras is enriched at the leading edge, promoting the localized activation of key chemotactic effectors, such as PI3K and TORC2 [2-5]. To investigate the role of Ras in directional sensing, we studied the effect of its misregulation by using cells with disrupted RasGAP activity. We identified an ortholog of mammalian NF1, DdNF1, as a major regulator of Ras activity in Dictyostelium. We show that disruption of nfaA leads to spatially and temporally unregulated Ras activity, causing cytokinesis and chemotaxis defects. By using unpolarized, latrunculin-treated cells, we show that tight regulation of Ras is important for gradient sensing. Together, our findings suggest that Ras is part of the cell's compass and that the RasGAP-mediated regulation of Ras activity affects directional sensing.

Original languageEnglish (US)
Pages (from-to)1587-1593
Number of pages7
JournalCurrent Biology
Issue number20
StatePublished - Oct 28 2008



ASJC Scopus subject areas

  • General Agricultural and Biological Sciences
  • General Biochemistry, Genetics and Molecular Biology
  • General Neuroscience


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