dictyNews
Electronic Edition
Volume 42, number 13
May 6, 2016
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Abstracts
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Oral administration of Dictyostelium differentiation-inducing
factor 1 lowers blood glucose levels in streptozotocin-induced
diabetic rats
Ritsuko Kawaharada, Akio Nakamura, Katsunori Takahashi, Haruhisa
Kikuchi, Yoshiteru Oshima, Yuzuru Kubohara*
*Graduate School of Health and Sports Science, Juntendo University,
Inzai City, 270-1695, Japan.
Life Sciences, in press
Aims: Differentiation-inducing factor 1 (DIF-1), originally
discovered in the cellular slime mold Dictyostelium discoideum,
and its derivatives possess pharmacological activities, such as
the promotion of glucose uptake in non-transformed mammalian
cells in vitro. Accordingly, DIFs are considered promising lead
candidates for novel anti-diabetic drugs. The aim of this study
was to assess the anti-diabetic and toxic effects of DIF-1 in
mouse 3T3-L1 fibroblast cells in vitro and in diabetic rats
in vivo.
Main methods: We investigated the in vitro effects of DIF-1 and
DIF-1(3M), a derivative of DIF-1, on glucose metabolism in 3T3-L1
cells by using capillary electrophoresis time-of-flight mass
spectrometry (CE-TOF-MS). We also examined the effects of DIF-1
on blood glucose levels in streptozotocin (STZ)-induced rats.
Key findings: CE-TOF-MS revealed that 20 microM DIF-1 and 20
microM DIF-1(3M) promoted glucose uptake and metabolism in
3T3-L1 cells. Oral administration of DIF-1 (30 mg/kg) significantly
lowered basal blood glucose levels in STZ-treated rats and
promoted a decrease in blood glucose levels after oral glucose
loading (2.5 g/kg) in the rats. In addition, daily oral
administration of DIF-1 (30 mg/kg/day) for 1 wk significantly
lowered the blood glucose levels in STZ-treated rats but did not
affect their body weight and caused only minor alterations in
the levels of other blood analytes.
Significance: These results indicate that DIF-1 may be a good
lead compound for the development of anti-diabetic drugs.
submitted by: Yuzuru Kubohara [[log in to unmask]]
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Quantitative imaging of Rac1 activity in Dictyostelium cells with
a fluorescently labelled GTPase-binding domain from DPAKa kinase
Maja Marinović, Marko Šoštar, Vedrana Filić, Vlatka Antolović,
Igor Weber
Histochemistry and Cell Biology,
http://link.springer.com/article/10.1007/s00418-016-1440-9
Small Rho GTPases are major regulators of the actin cytoskeleton
dynamics in eukaryotic cells. Sophisticated tools used to investigate
their activity in living cells include probes based on fluorescence
resonance energy transfer (FRET), bimolecular fluorescence
complementation, and photoactivation. However, such methods are
of limited use in quickly migrating cells due to a short time available
for image acquisition leading to a low signal-to-noise ratio. Attempts
to remedy this effect by increasing the intensity of illumination are
restricted by photobleaching of probes and the cell photosensitivity.
Here we present design and characterization of a new fluorescent probe
that selectively binds to active form of Rac1 GTPases, and demonstrate
its superior properties for imaging in highly motile Dictyostelium
cells. The probe is based on the GTPase-binding domain (GBD) from
DPAKa kinase and was selected on the basis of yeast two-hybrid screen,
GST pull-down assay and FRET measurements by fluorescence lifetime
imaging microscopy. DPAKa(GBD) probe binds specifically to GTP-bound
Rac1 at the cell membrane and features a low cytoplasmic background.
The main advantage of DPAKa(GBD) in comparison with similar probes
is its finely graded intensity distribution along the entire plasma
membrane, which enables quantitative measurements of the Rac1 activity
in different parts of the membrane. Finally, expression of DPAKa(GBD)
induces no adverse effects on cell growth, motility and cytokinesis.
submitted by: Maja Marinović [[log in to unmask]]
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[End dictyNews, volume 42, number 13]
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