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dictyNews Volume 38 Number 21
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
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Abstracts
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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]
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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]
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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]
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[End dictyNews, volume 38, number 21]
