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dictyNews Volume 39 Number 10
dictyNews
Electronic Edition
Volume 39, number 10
April 5, 2013
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.
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Abstracts
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Dictyostelium genes dysregulated in an O-glycosylation mutant
identified by mRNA differential display
Motonobu Yoshida, Naoya Sakuragi, Eiji Tanesaka, Yutaka Sendai
Lab of Plant Breeding and Agrobiotechnology, Department of
Agricultural Science, Kinki University, Nakamachi 3327-204,
Nara 631-8505, Japan
J. Biotechnol. Biomater. doi:10.4172/2155-952X.1000152, in press
Seven differentially-expressed cDNA clones were isolated by using
an mRNA differential display between a Dictyostelium wild-type AX2
and a mutant HG794 defective in O-glycosylation. Transcript levels for
the seven clones were reduced or not detectable in the mutant HG794.
Homology search showed that the four cDNA clones, DD-3 and DD-7~9
are novel and that three cDNA clones, DD-4 and DD-5, -6 encode an actin-
bundling protein and phosphodiesterase inhibitors, respectively. Full-length
cDNAs for DD-3 and -8 were isolated and labeled DD3-3 and DD8-14,
respectively. DD3-3 consists of 2,166 bp and DD8-14 of 2,084 bp. DD3-3
was preliminarily reported in a previous paper (Sakuragi et al., 2005).
SSL850 was named a clone by the "Dictyostelium cDNA Project in Japan",
containing a full-length cDNA for DD-7 and was labeled DD7-1 of 902 bp.
It has 60% homology with discoidin Ia. DD8-14 most likely has no direct
role in glycosylation, while DD3-3 and DD7-1 very likely are involved in
some aspect of recognition of glycosylation.
Submitted by Motonobu Yoshida [yoshida_m@nara.kindai.ac.jp]
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Dictyostelium discoideum SecG interprets cAMP mediated chemotactic
signals to influence actin organization
Rebecca Garcia, Liem Nguyen, and Derrick Brazill
Cytoskeleton, in press
Tight control of actin cytoskeletal dynamics is essential for proper cell
function and survival. ARNO, a mammalian guanine nucleotide exchange
factor for Arf, has been implicated in actin cytoskeletal regulation but its
exact role is still unknown. To explore the role of ARNO in this regulation
as well as in actin-mediated processes, the Dictyostelium discoideum
homolog, SecG, was examined. SecG peaks during aggregation and
mound formation. The overexpression of SecG arrests development at the
mound stage. SecG overexpressing (SecG OE) cells fail to stream during
aggregation. Although carA is expressed, SecG OE cells do not chemotax
toward cAMP, indicating SecG is involved in the cellular response to cAMP.
This chemotactic defect is specific to cAMP-directed chemotaxis, as SecG
OE cells chemotax to folate without impairment and exhibit normal cell
motility. The chemotactic defects of the SecG mutants may be due to an
impaired cAMP response as evidenced by altered cell polarity and F-actin
polymerization after cAMP stimulation. Cells overexpressing SecG have
increased filopodia compared to wild type cells, implying that excess SecG
causes abnormal organization of F-actin. The general function of the
cytoskeleton, however, is not disrupted as the SecG OE cells exhibit proper
cell-substrate adhesion. Taken together, the results suggest proper SecG
levels are needed for appropriate response to cAMP signaling in order to
coordinate F-actin organization during development.
Submitted by Derrick Brazill [brazill@genectr.hunter.cuny.edu]
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[End dictyNews, volume 39, number 10]
