dictyNews
Electronic Edition
Volume 47, number 12
June 4, 2021
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Abstracts
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Dynamics of Myosin II Filaments during Wound Repair in Dividing
Cells
Md. Istiaq Obaidi Tanvir , Go Itoh , Hiroyuki Adachi and Shigehiko
Yumura
Cells, in press
Wound repair of cell membranes is essential for cell survival.
Myosin II contributes to wound pore closure by interacting with
actin filaments in larger cells; however, its role in smaller cells
is unclear. In this study, we observed wound repair in dividing
cells for the first time. The cell membrane in the cleavage furrow,
where myosin II localized, was wounded by laserporation. Upon
wounding, actin transiently accumulated, and myosin II transiently
disappeared from the wound site. Ca2+ influx from the external
medium triggered both actin and myosin II dynamics. Inhibition
of calmodulin reduced both actin and myosin II dynamics. The
wound closure time in myosin II-null cells was the same as that
in wild-type cells, suggesting that myosin II is not essential for
wound repair. We also found that disassembly of myosin II
filaments by phosphorylation did not contribute to their
disappearance, indicating a novel mechanism for myosin II
delocalization from the cortex. Furthermore, we observed that
several furrow-localizing proteins such as GAPA, PakA, myosin
heavy chain kinase C, PTEN, and dynamin disappeared upon
wounding. Herein, we discuss the possible mechanisms of
myosin dynamics during wound repair.
submitted by: Shigehiko Yumura [[log in to unmask]]
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RNAseq and quantitative proteomic analysis of Dictyostelium
knock-out cells lacking the core autophagy proteins ATG9
and/or ATG16
Qiuhong Xiong, Ning Song, Ping Li, Sarah Fischer, Roman Konertz,
Prerana Wagle, Gernot Glöckner, Changxin Wu, and
Ludwig Eichinger
BMC Genomics, accepted
Background: Autophagy is an evolutionary ancient mechanism
that sequesters substrates for degradation within autolysosomes.
The process is driven by many autophagy-related (ATG) proteins,
including the core members ATG9 and ATG16. However, the
functions of these two core ATG proteins still need further
elucidation. Here, we applied RNAseq and tandem mass tag (TMT)
proteomic approaches to identify differentially expressed genes
(DEGs) and proteins (DEPs) in Dictyostelium discoideum ATG9-,
ATG16- and ATG9-/16- strains in comparison to AX2 wild-type cells.
Result: In total, we identified 332 (279 up and 53 down), 639
(487 up and 152 down) and 260 (114 up and 146 down) DEGs
and 124 (83 up and 41 down), 431 (238 up and 193 down) and 677
(347 up and 330 down) DEPs in ATG9-, ATG16- and ATG9-/16-
strains, respectively. Thus, in the single knock-out strains, the
number of DEGs was higher than the number of DEPs while in
the double knock-out strain the number of DEPs was higher.
Comparison of RNAseq and proteomic data further revealed, that
only a small proportion of the transcriptional changes were reflected
on the protein level. Gene ontology (GO) analysis revealed an
enrichment of DEPs involved in lipid metabolism and oxidative
phosphorylation. Furthermore, we found increased expression of
the anti-oxidant enzymes glutathione reductase (gsr) and catalase
A (catA) in ATG16- and ATG9-/16- cells, respectively, indicating
adaptation to excess reactive oxygen species (ROS).
Conclusions: Our study provides the first combined transcriptome
and proteome analysis of ATG9-, ATG16- and ATG9-/16- cells. Our
results suggest, that most changes in protein abundance were not
caused by transcriptional changes, but were rather due to changes
in protein homeostasis. In particular, knock-out of Atg9 and/or
Atg16 appears to cause dysregulation of lipid metabolism and
oxidative phosphorylation.
submitted by: Ludwig Eichinger [[log in to unmask]]
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[End dictyNews, volume 47, number 12]
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