dictyNews Electronic Edition Volume 34, number 19 June 25, 2010 Please submit abstracts of your papers as soon as they have been accepted for publication by sending them to dicty@northwestern.edu or by using the form at http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit. Back issues of dictyNews, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. Follow dictyBase on twitter: http://twitter.com/dictybase ========= Abstracts ========= Self-organization of the phosphatidylinositol lipids signaling system for random cell migration Yoshiyuki Arai, Tatsuo Shibata, Satomi Matsuoka, Masayuki J. Sato, Toshio Yanagida, and Masahiro Ueda Graduate School of Frontier Biosciences, Osaka University and JST, CREST, Suita, Osaka 565-0871, Japan. Department of Mathematical and Life Sciences, Hiroshima University and JST, PRESTO, Higashi-Hiroshima, Hiroshima 739-8526, Japan. Proc. Natl. Acad. Sci. USA , in press. Phosphatidylinositol (PtdIns) lipids have been identified as key signaling mediators for random cell migration as well as chemoattractant-induced directional migration. However, how the PtdIns lipids are organized spatiotemporally to regulate cellular motility and polarity remains to be clarified. Here, we found that selforganized waves of PtdIns 3,4,5-trisphosphate [PtdIns(3,4,5)P3] are generated spontaneously on the membrane of Dictyostelium cells in the absence of a chemoattractant. Characteristic oscillatory dynamics within the PtdIns lipids signaling system were determined experimentally by observing the phenotypic variability of PtdIns lipid waves in single cells, which exhibited characteristics of a relaxation oscillator. The enzymes phosphatase and tensin homolog (PTEN) and phosphoinositide-3-kinase (PI3K), which are regulators for PtdIns lipid concentrations along the membrane, were essential for wave generation whereas functional actin cytoskeleton was not. Defects in these enzymes inhibited wave generation as well as actin-based polarization and cell migration. On the basis of these experimental results, we developed a reaction-diffusion model that reproduced the characteristic relaxation oscillation dynamics of the PtdIns lipid system, illustrating that a self-organization mechanism provides the basis for the PtdIns lipids signaling system to generate spontaneous spatiotemporal signals for random cell migration and that molecular noise derived from stochastic fluctuations within the signaling components gives rise to the variability of these spontaneous signals. Submitted by Masahiro Ueda [ueda@phys1.med.osaka-u.ac.jp] -------------------------------------------------------------------------------- Glycogen Synthase Kinase-3 Is Required for Efficient Dictyostelium Chemotaxis Regina Teo, Kimberley J. Lewis, Josephine E. Forde, W. Jonathan Ryves, Jonathan V. Reddy, Benjamin J. Rogers, and Adrian J. Harwood Molecular Biology of the Cell (in press) epub 10.1091/mbc.E09-10-0891 Glycogen synthase kinase-3 (GSK3) is a highly conserved protein kinase that is involved in several important cell signaling pathways and is associated with a range of medical conditions. Previous studies indicated a major role of the Dictyostelium homologue of GSK3 (gskA) in cell fate determination during morphogenesis of the fruiting body; however, transcriptomic and proteomic studies have suggested that GSK3 regulates gene expression much earlier during Dictyo- stelium development. To investigate a potential earlier role of GskA, we examined the effects of loss of gskA on cell aggregation. We find that cells lacking gskA exhibit poor chemotaxis toward cAMP and folate. Mutants fail to activate two important regulatory signaling pathways, mediated by phosphatidylinositol 3,4,5-trisphosphate and target of rapamycin complex 2, which in combination are required for chemotaxis and cAMP signaling. These results indicate that GskA is required during early stages of Dictyostelium development, in which it is necessary for both chemotaxis and cell signaling. Submitted by Adrian Harwood [harwoodaj@cardiff.ac.uk] ============================================================== [End dictyNews, volume 34, number 19]