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dictyNews Volume 31 Number 08
dictyNews
Electronic Edition
Volume 31, number 8
August 29, 2008
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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Back issues of dictyNews, the Dicty Reference database and other
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Abstracts
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Exploitation of the derivatives of Dictyostelium differentiation-inducing
factor-1, which promote glucose consumption in mammalian cells
Yuzuru Kubohara*, Haruhisa Kikuchi, Yoshiteru Oshima
Institute for Molecular and Cellular Regulation (IMCR), Gunma University,
Maebashi 371-8512, Japan (YK),
Laboratory of Natural Product Chemistry, Graduate School of Pharmaceutical
Sciences, Tohoku University, Japan (HK, YO)
Life Sciences, In press
Aims: The differentiation-inducing factor-1 (DIF-1) is a signal molecule
that induces stalk cell formation in the cellular slime mold Dictyostelium
discoideum. DIF-1 has also been shown to possess pharmacological activities,
such as the suppression of tumor cell growth and the promotion of glucose
uptake in non-transformed mammalian cells. In this study, we tried to develop
compounds that possess weaker anti-tumor activity and stronger glucose
uptake-promoting activity than DIF-1.
Main methods: We investigated the in vitro effects of 12 derivatives of DIF-1
on glucose consumption in mouse 3T3-L1 cells and on cell growth in K562
human leukemia cells. We also examined the effect of a good compound on
the blood glucose concentration in KK-Ay diabetic mice.
Key findings: We found that some derivatives at 20 uM promoted glucose
consumption more than twice as fast as the control. Of the derivatives, a
compound named DIF-1(3M), which has a weaker anti-leukemic effect than
DIF-1, promoted glucose consumption as strongly as DIF-1 in confluent
3T3-L1 cells. While DIF-1 at 20 uM was inhibitory to the cell growth of
3T3-L1, DIF-1(3M) at 20 uM exhibited no inhibitory effect on the growing
cells. We also found that DIF-1(3M) injected (10-12.5 mg/kg body weight)
intraperitoneally in mice tended to lower the blood glucose concentration.
Significance: The present results open the possibility for the development
of new agents that possess strong glucose-uptake-promoting activity but
little anti-tumor activity and may have therapeutic potential for the
treatment of diabetes and/or obesity.
Submitted by: Yuzuru Kubohara [kubohara@showa.gunma-u.ac.jp]
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An ELMO-like protein associated with myosinII restricts spurious F-actin
events to coordinate phagocytosis and chemotaxis
Nilgun Isik, Ph.D.; Joseph A Brzostowski, Ph.D.^; Tian Jin, Ph.D.
Chemotaxis Signal Section, Laboratory of Immunogenetics, National Institute
of Allergy and Infectious Diseases, NIH, Twinbrook II Facility, 12331
Parklawn Drive, Rockville, Maryland 20852, USA
^Laboratory of Immunogenetics Light Imaging Facility, National Institute of
Allergy and Infectious Diseases, NIH, Twinbrook II Facility, 12331 Parklawn
Drive, Rockville, Maryland 20852, USA
Developmental Cell, in press
Elmo proteins positively regulate actin polymerization during cell migration
and phagocytosis through activation of the small G-protein Rac. We
identified an Elmo-like protein, ElmoA, in Dictyostelium discoideum that
unexpectedly functions as a negative regulator of actin polymerization.
Cells lacking ElmoA display an elevated rate of phagocytosis, increased
pseudopod formation and excessive F-actin localization within pseudopods.
ElmoA associates with cortical actin and myosin II. TIRF microscopic
observations of functional ElmoA-GFP reveal that a fraction of ElmoA
localizes near the presumptive actin/myosin II cortex and the levels of
ElmoA and myosin II negatively correlate with that of polymerizing F-actin.
F-actin-regulated dynamic dispersions of ElmoA and myosin II are
interdependent. Taken together, our data suggest that ElmoA modulates
actin/myosin II at the cortex to prevent excessive F-actin polymerization
around the cell periphery, thereby maintaining proper cell shape during
phagocytosis and chemotaxis.
Submitted by: Joe Brzostowski [brzostowskij@niaid.nih.gov]
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[End dictyNews, volume 31, number 8]
