dictyNews
Electronic Edition
Volume 43, number 2
January 27, 2017
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Abstracts
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Co-existence of Ras activation in a chemotactic signal transduction
pathway and in an autonomous wave - forming system
Mary Ecke1 and Günther Gerisch1
1Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152
Martinsried, Germany.
SmallGTPases, in press
The activation of Ras is common to two activities in cells of
Dictyostelium discoideum: the directed movement in a gradient of
chemoattractant and the autonomous generation of propagating
waves of actin polymerization on the substrate-attached cell surface.
We produced large cells by electric-pulse induced fusion to
simultaneously study both activities in one cell. For imaging, a
fluorescent label for activated Ras was combined with labels for
filamentous actin, PIP3, or PTEN. Chemotactic responses were
elicited in a diffusion gradient of cyclic AMP. Waves initiated at sites
separate from the front of the cell propagated in all directions.
Nevertheless, the wave-forming cells were capable of recognizing
the attractant gradient and managed to migrate in its direction.
submitted by: Günther Gerisch [[log in to unmask]]
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The Arp2/3 inhibitory protein Arpin is dispensable for chemotaxis
Irène Dang 1, Joern Linkner 2, Jun Yan 3, Daniel Irimia 3,
Jan Faix 2, Alexis Gautreau 1.
1 Ecole Polytechnique, Université Paris-Saclay, CNRS UMR7654,
Palaiseau 91120, France.
2 Institute for Biophysical Chemistry, Hannover Medical School,
Hannover 30625, Germany.
3 Massachusetts General Hospital and Harvard Medical School,
BioMEMS Resource Center, Boston, MA 02129,USA.
Biology of the Cell, in press
Arpin is an Arp2/3 inhibitory protein, which decreases the protrusion
lifetime and hence directional persistence in the migration of diverse
cells. Arpin is activated by the small GTPase Rac, which controls cell
protrusion, thus closing a negative feedback loop that renders the
protrusion intrinsically unstable. Because of these properties, it was
proposed that Arpin might play a role in directed migration, where
directional persistence has to be finetuned. We report here, however,
that Arpin depleted tumor cells and Arpin knock-out Dictyostelium
amoeba display no obvious defect in chemotaxis. These results do
not rule out a potential role of Arpin in other systems, but argue
against a general role of Arpin in chemotaxis.
submitted by: Jan Faix [[log in to unmask]]
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Tipping the scales: Lessons from simple model systems on inositol
imbalance in neurological disorders
Anna D Frej, Grant P Otto, Robin SB Williams*
European Journal of Cell Biology, In Press
Inositol and inositol-containing compounds have signalling and
regulatory roles in many cellular processes, suggesting that inositol
imbalance may lead to wide-ranging changes in cellular functions.
Indeed, changes in inositol-dependent signalling have been implicated
in various diseases and cellular functions such as autophagy, and
these changes have often been proposed as therapeutic targets.
However, few studies have highlighted the links between inositol
depletion and the downstream effects on inositol phosphates and
phosphoinositides in disease states. For this research, many advances
have employed simple model systems that include the social amoeba
D. discoideum and the yeast S. cerevisiae, since these models enable
a range of experimental approaches that are not possible in
mammalian models. In this review, we discuss recent findings initiated
in simple model systems and translated to higher model organisms
where the effect of altered inositol, inositol phosphate and
phosphoinositide levels impact on bipolar disorder, Alzheimer disease,
epilepsy and autophagy.
submitted by: Robin Williams [[log in to unmask]]
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[End dictyNews, volume 43, number 2]
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