dictyNews Electronic Edition Volume 43, number 26 November 10, 2017 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 ========= Cln5 is secreted and functions as a glycoside hydrolase in Dictyostelium Robert J. Huber and Sabateeshan Mathavarajah Department of Biology, Trent University, Peterborough, Ontario, Canada Cellular Signalling, in press Ceroid lipofuscinosis neuronal 5 (CLN5) is a member of a family of proteins that are linked to neuronal ceroid lipofuscinosis (NCL). This devastating neurological disorder, known commonly as Batten disease, affects all ages and ethnicities and is currently incurable. The precise function of CLN5, like many of the NCL proteins, remains to be elucidated. In this study, we report the localization, molecular function, and interactome of Cln5, the CLN5 homolog in the social amoeba Dictyostelium discoideum. Residues that are glycosylated in human CLN5 are conserved in the Dictyostelium homolog as are residues that are mutated in patients with CLN5 disease. Dictyostelium Cln5 contains a putative signal peptide for secretion and we show that the protein is secreted during growth and starvation. We also reveal that both Dictyostelium Cln5 and human CLN5 are glycoside hydrolases, providing the first evidence in any system linking a molecular function to CLN5. Finally, immunoprecipitation coupled with mass spectrometry identified 61 proteins that interact with Cln5 in Dictyostelium. Of the 61 proteins, 67% localize to the extracellular space, 28% to intracellular vesicles, and 20% to lysosomes. A GO term enrichment analysis revealed that a majority of the interacting proteins are involved in metabolism, catabolism, proteolysis, and hydrolysis, and include other NCL-like proteins (e.g., Tpp1/Cln2, cathepsin D/Cln10, cathepsin F/Cln13) as well as proteins linked to Cln3 function in Dictyostelium (e.g., AprA, CfaD, CadA). In total, this work reveals a CLN5 homolog in Dictyostelium and further establishes this organism as a complementary model system for studying the functions of proteins linked to NCL in humans. submitted by: Robert Huber [roberthuber@trentu.ca] —————————————————————————————————————— WASP family proteins and Formins Compete in Pseudopod- and Bleb-based Migration Andrew Davidson, Clelia Amato, Peter Thomason and Robert Insall J Cell Biol., accepted Actin pseudopods induced by SCAR/WAVE drive normal migration and chemotaxis in eukaryotic cells. Cells can also migrate using blebs, in which the edge is driven forwards by hydrostatic pressure instead of actin. In Dictyostelium, loss of SCAR is compensated by WASP moving to the leading edge to generate morphologically normal pseudopods. Here we use an inducible double knockout to show that cells lacking both SCAR and WASP are unable to grow, make pseudopods or, unexpectedly, migrate using blebs. Remarkably, amounts and dynamics of actin polymerization are normal. Pseudopods are replaced in double SCAR/WASP mutants by aberrant filopods, induced by the formin dDia2. Further disruption of the gene for dDia2 restores cells’ ability to initiate blebs and thus migrate, though pseudopods are still lost. Triple knockout cells still contain near-normal F-actin levels. This work shows that SCAR, WASP and dDia2 compete for actin. Loss of SCAR and WASP causes excessive dDia2 activity, maintaining F-actin levels but blocking pseudopod and bleb formation and migration. submitted by: Robert Insall [r.insall@beatson.gla.ac.uk] —————————————————————————————————————— Curcumin affects gene expression and reactive oxygen species via a PKA dependent mechanism in Dictyostelium discoideum William S. Swatson 1, Mariko Katoh-Kurasawa 2, Gad Shaulsky 2*, Stephen Alexander 1* 1 Division of Biological Sciences, University of Missouri, Columbia, MO 65211, United States 2 Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, United States *Corresponding authors Correspondence to Stephen Alexander, alexanderst@missouri.edu, and Gad Shaulsky, gadi@bcm.edu PLOS ONE November 6, 2017, accepted Botanicals are widely used as dietary supplements and for the prevention and treatment of disease. Despite a long history of use, there is generally little evidence supporting the efficacy and safety of these preparations. Curcumin has been used to treat a myriad of human diseases and is widely advertised and marketed for its ability to improve health, but there is no clear understanding how curcumin interacts with cells and affects cell physiology. D. discoideum is a simple eukaryotic lead system that allows both tractable genetic and biochemical studies. The studies reported here show novel effects of curcumin on cell proliferation and physiology, and a pleiotropic effect on gene transcription. Transcriptome analysis showed that the effect is two-phased with an early transient effect on the transcription of approximately 5% of the genome, and demonstrates that cells respond to curcumin through a variety of previously unknown molecular pathways. This is followed by later unique transcriptional changes and a protein kinase A dependent decrease in catalase A and three superoxide dismutase enzymes. Although this results in an increase in reactive oxygen species (ROS; superoxide and H2O2), the effects of curcumin on transcription do not appear to be the direct result of oxidation. This study opens the door to future explorations of the effect of curcumin on cell physiology. submitted by: Steven Alexander [alexanderst@missouri.edu] ============================================================== [End dictyNews, volume 43, number 26]