Dicty News Electronic Edition Volume 22, number 17 June 25, 2004 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 Dicty-News, the Dicty Reference database and other useful information is available at dictyBase - http://dictybase.org. ============= Abstracts ============= Extracellular matrix family proteins that are potential targets of Dd-STATa in Dictyostelium discoideum Nao Shimada1, Keiko Nishio2, Mineko Maeda2, Hideko Urushihara3 and Takefumi Kawata1, 4 1Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama, Funabashi, Chiba 274-8510, JAPAN TEL & FAX: 81-47-472-5156, E-mail: tkawata@bio.sci.toho-u.ac.jp 2 Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 3 Biological Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572 4 Corresponding author J. Plant Res., in press Dd-STATa is a functional Dictyostelium homologue of metazoan STAT (signal transducers and activators of transcription) proteins, which is activated by cAMP and is thereby translocated into the nuclei of anterior tip cells of the prestalk region of the slug. By using in situ hybridization analyses, we found that the SLF308 cDNA clone, which contains the ecmF gene that encodes a putative extracellular matrix protein and is expressed in the anterior tip cells, was greatly down-regulated in the Dd-STATa-null mutant. Disruption of the ecmF gene, however, resulted in almost no phenotypic change. The absence of any obvious mutant phenotype in the ecmF-null mutant could be due to a redundancy of similar genes. In fact, a search of the Dictyostelium whole genome database demonstrates the existence of additional 16 homologues, all of which contain a cellulose-binding module. Among these homologues, four genes show Dd-STATa-dependent expression, while the others were Dd-STATa-independent. We discuss the potential role of Dd-STATa in morphogenesis via its effect on the interaction between cellulose and these extracellular matrix family proteins. Submitted by: Takefumi Kawata [tkawata@bio.sci.toho-u.ac.jp] ----------------------------------------------------------------------------- GSK-3 is a multi-functional regulator of Dictyostelium development Christina Schilde, Tsuyoshi Araki, Hazel Williams*, Adrian Harwood*, and Jeffrey G. Williams School of Life Sciences, Wellcome Trust Biocentre, University of Dundee, Dundee DD1 5EH, UK * MRC Laboratory for Molecular Cell Biology & Dept of Biology, University College, Gower St, London WC1E 6BT Development, in press Glycogen Synthase Kinase-3 (GSK-3) is a central regulator of metazoan development and the Dictyostelium GSK-3 homologue, GskA, also controls cellular differentiation. The originally derived gskA null mutant exhibits a severe pattern formation defect. It forms very large numbers of pre-basal disc cells at the expense of the prespore population. This defect arises early during multicellular development, making it impossible to examine later functions of GskA. We report the analysis of a gskA null mutant, generated in a different parental strain, which proceeds through development to form mature fruiting bodies. In this strain, Ax2/gskA-, early development is accelerated and slug migration greatly curtailed. In a monolayer assay of stalk cell formation, the Ax2/gskA- strain is hyper-sensitive to the stalk cell inducing action of DIF-1 but largely refractory to the repressive effect exerted by extracellular cAMP. During normal development apically situated prestalk cells express the ecmB gene just as they commit themselves to stalk cell differentiation. In the Ax2/gskA- mutant ecmB is expressed throughout the prestalk region of the slug, suggesting that GskA forms part of the repressive signalling pathway that prevents premature commitment to stalk cell differentiation. GskA may also play an inductive developmental role, because micro-array analysis identifies a large gene family, the 2C family, that require gskA for optimal expression. These observations show that GskA functions throughout Dictyostelium development, to regulate several key aspects of cellular patterning. Submitted by: Jeff Williams [j.g.williams@dundee.ac.uk] ----------------------------------------------------------------------------- Chemotaxis: signalling the way forward Peter J.M. Van Haastert1 and Peter N Devreotes2 1Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands 2 Department of Cell Biology , Johns Hopkins University School of Medicine, 725 N. Wolfe St., 114 WBSB Baltimore, MD 21205, USA Nature Reviews Molecular Cell Biology, in press During random locomotion, human neutrophils and Dictyostelium discoideum amoebae repeatedly extend and retract cytoplasmic processes. During directed cell migration ? chemotaxis ? these pseudopodia form predominantly at the leading edge in response to the local accumulation of certain signalling molecules. Concurrent changes in actin and myosin enable the cell to move towards the stimulus. Recent studies are beginning to identify an intricate network of signalling molecules that mediate these processes, and how these molecules become localized in the cell. Submitted by: Peter van Haastert"