dictyNews
Electronic Edition
Volume 49, number 9
March 24, 2023
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Abstracts
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Self-cleaving peptides for expression of multiple genes in Dictyostelium
discoideum
Xinwen Zhu, Chiara Ricci-Tam, Emily R. Hager, Allyson E. Sgro
Published: March 2, 2023
https://doi.org/10.1371/journal.pone.0281211
The social amoeba Dictyostelium discoideum is a model for a wide
range of biological processes including chemotaxis, cell-cell
communication, phagocytosis, and development. Interrogating these
processes with modern genetic tools often requires the expression of
multiple transgenes. While it is possible to transfect multiple
transcriptional units, the use of separate promoters and terminators
for each gene leads to large plasmid sizes and possible interference
between units. In many eukaryotic systems this challenge has been
addressed through polycistronic expression mediated by 2A viral
peptides, permitting efficient, co-regulated gene expression. Here, we
screen the most commonly used 2A peptides, porcine
teschovirus-1 2A (P2A), Thosea asigna virus 2A (T2A), equine rhinitis
A virus 2A (E2A), and foot-and-mouth disease virus 2A (F2A), for
activity in D. discoideum and find that all the screened 2A sequences
are effective. However, combining the coding sequences of two proteins
into a single transcript leads to notable strain-dependent decreases in
expression level, suggesting additional factors regulate gene expression
in D. discoideum that merit further investigation. Our results show that
P2A is the optimal sequence for polycistronic expression in D. discoideum,
opening up new possibilities for genetic engineering in this model system.
Submitted by Xinwen Zhu [[log in to unmask]]
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Controlling periodic long-range signalling to drive a morphogenetic
transition
Hugh Z Ford, Angelika Manhart, Jonathan R Chubb
eLife; https://elifesciences.org/articles/83796
Cells use signal relay to transmit information across tissue scales.
However, the production of information carried by signal relay remains
poorly characterised. To determine how the coding features of signal relay
are generated, we used the classic system for long-range signalling: the
periodic cAMP waves that drive Dictyostelium collective migration.
Combining imaging and optogenetic perturbation of cell signalling states,
we find that migration is triggered by an increase in wave frequency
generated at the signalling centre. Wave frequency is regulated by cAMP
wave circulation, which organises the long-range signal. To determine the
mechanisms modulating wave circulation, we combined mathematical
modelling, the general theory of excitable media and mechanical
perturbations to test competing models. Models in which cell density and
spatial patterning modulate the wave frequency cannot explain the
temporal evolution of signalling waves. Instead, our evidence leads to a
model where wave circulation increases the ability for cells to relay the
signal, causing further increase in the circulation rate. This positive
feedback between cell state and signalling pattern regulates the long-
range signal coding that drives morphogenesis.
Submitted by Jonathan Chubb [[log in to unmask]]
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[End dictyNews, volume 49, number 9]
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