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dictyNews Volume 23 Number 01
Dicty News
Electronic Edition
Volume 23, number 1
July 09, 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.
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Abstracts
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A novel partner for Dictyostelium filamin is an a-helical, developmentally
regulated protein
Monika Knuth,*1 Nandkumar Khaire,*1 Sijie Lu,¤ Adam Kuspa,¤ Michael
Schleicher,$ and Angelika A. Noegel*
Journal of Cell Science, in press
The filamins are a family of highly homologous actin-crosslinking proteins
that stabilize three-dimensional actin networks, link them to membrane
proteins and direct intracellular signaling reactions to the actin
scaffold through interaction with various binding partners. Here we
describe FIP, the first Dictyostelium filamin interacting protein isolated,
a 229.800 Da protein with two a-helical coiled coil domains. FIP was
identified in a yeast two hybrid screen using the rod domain of filamin as
bait. FIP can also be coimmunoprecipitated with filamin from cellular
extracts. Deletion analysis located the interaction domain of FIP to a
C-terminal region, whereas in filamin rod repeats 2-4 interacted with the
recombinant FIP protein. The 7 kb transcript of FIP is upregulated during
early development. Monoclonal antibodies raised against a bacterially
expressed FIP polypeptide recognize a 230-kDa developmentally regulated
protein in western blots. Immunofluorescence analysis shows a punctate
staining pattern in the cytosol and in cell fractionation experiments FIP
is mainly found in the cytosolic fraction. A fusion protein composed of GFP
and the C-terminal part localizes to the plasma membrane and is associated
with the cytoskeleton. Expression of the fusion protein affects development
and influences the size of the multicellular aggregates and the phototactic
behaviour of slugs. Thus, FIP might provide a candidate link between the
dynamic actin cytoskeleton and signal transduction events during the
multicellular stages of Dictyostelium amoebae.
Submitted by: Angelika Noegel [noegel@uni-koeln.de]
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Control of cell-type proportioning in Dictyostelium by DIF as determined by
in situ hybridization.
Toshinari Maruo,1 Haruyo Sakamoto,1 Negin Iranfar,2 Danny Fuller,2 Takahiro
Morio,3 Hideko Urushihara,3 Yoshimasa Tanaka3, Mineko Maeda1* and
William F. Loomis,2*
1Department of Biology, Graduate School of Science, Osaka University,
Toyonaka, Osaka 560-0043,
2Cell and Developmental Biology, Division of Biological Sciences, University
of California San Diego, La Jolla, California 92093, USA
3Institute of Biological Sciences, University of Tsukuba, Tsukuba,
Ibaraki 305-8572, Japan
Eukaryotic Cell, in press
We have determined the proportions of the prespore and prestalk regions in
Dictyostelium slugs by in situ hybridization with a large number of prespore
and prestalk specific genes. Microarrays were used to discover genes
expressed in a cell type specific manner. Fifty-four prespore specific
genes were verified by in situ hybridization including 18 that had been
previously shown to be cell type specific. The 36 new genes more than
doubles the number of available prespore markers. At the slug stage the
prespore genes hybridized to cells uniformly in the posterior 80% of
wild -type slugs but hybridized to the posterior 90% of slugs lacking
the secreted alkylphenone DIF-1. There was a compensatory two-fold
decrease in prestalk cells in DIF-less slugs. Removal of prespore cells
resulted in cell type conversion in both wild-type and DIF-less anterior
fragments. Thus, DIF-1 appears to act in concert with other processes to
establish cell-type proportions.
Submitted by: Bill Loomis [wloomis@ucsd.edu]
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[End Dicty News, volume 23, number 1]
