dictyNews Electronic Edition Volume 38, number 21 August 17, 2012 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 ========= Alpha-Catenin and IQGAP Regulate Myosin Localization to Control Epithelial Tube Morphogenesis in Dictyostelium Daniel J. Dickinson, Douglas N. Robinson, W. James Nelson and William I. Weis Developmental Cell, in press Apical actomyosin activity in animal epithelial cells influences tissue morphology, and drives morphogenetic movements during development. The molecular mechanisms leading to myosin II accumulation at the apical membrane and its exclusion from other membranes are poorly understood. We show that in the non-metazoan Dictyostelium discoideum, myosin II localizes apically in tip epithelial cells that surround the stalk, and constriction of this epithelial tube is required for proper morphogenesis. IQGAP1 and its binding partner cortexillin I function downstream of alpha- and beta-catenin to exclude myosin II from the basolateral cortex and promote apical accumulation of myosin II. Deletion of IQGAP1 or cortexillin compromises epithelial morphogenesis without affecting cell polarity. These results reveal that apical localization of myosin II is a conserved morphogenetic mechanism from non-metazoans to vertebrates, and identify a hierarchy of proteins that regulate the polarity and organization of an epithelial tube in a simple model organism. Submitted by Daniel Dickinson [ddickins@live.unc.edu] --------------------------------------------------------------------------- An Epithelial Tissue in Dictyostelium Challenges the Traditional Origin of Metazoan Multicellularity Daniel J. Dickinson, W. James Nelson and William I. Weis Bioessays, in press We hypothesize that aspects of animal multicellularity originated before the divergence of metazoans from fungi and social amoebae. Polarized epithelial tissues are a defining feature of metazoans and contribute to the diversity of animal body plans. The recent finding of a polarized epithelium in the nonmetazoan social amoeba Dictyostelium discoideum demonstrates that epithelial tissue is not a unique feature of metazoans and challenges the traditional paradigm that multicellularity evolved independently in social amoebae and metazoans. An alternative view, presented here, is that the common ancestor of social amoebae, fungi, and animals spent a portion of its life cycle in a multicellular state and possessed molecular machinery necessary for forming an epithelial tissue. Some descendants of this ancestor retained multicellularity, while others reverted to unicellularity. This hypothesis makes testable predictions regarding tissue organization in close relatives of metazoans and provides a novel conceptual framework for studies of early animal evolution. Submitted by Daniel Dickinson [ddickins@live.unc.edu] ----------------------------------------------------------------------------- Isolation, Synthesis and Biological Activity of Biphenyl and m-Terphenyl-Type Compounds from Dictyostelium Cellular Slime Molds Haruhisa Kikuchi,* Yusuke Matsuo, Yasuhiro Katou, Yuzuru Kubohara, and Yoshiteru Oshima Tetrahedron, in press. From the fruiting bodies of Dictyostelium polycephalum, we obtained four aromatic compounds: dictyobiphenyl A (1) and B (2) and dictyoterphenyl A (3) and B (4). The synthesis of 1-4 was performed to confirm the structures and obtain sufficient material for biological evaluation. Compound 3 was the first example of nitrogen-containing natural m-terphenyls, and the isolation of novel classes of compounds such as 3 shows that cellular slime molds are promising sources in natural product chemistry. Moreover, dictyoterphenyl A (3) showed cancer cell-selective antiproliferative activity (IC50 2.3~8.6 uM). Submitted by Haruhisa Kikuchi [hal@mail.pharm.tohoku.ac.jp] ============================================================== [End dictyNews, volume 38, number 21]