Jan-Feb 2014 ASCB Newsletter - page 56-57

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56
ASCB
NEWSLETTER JANUARY/FEBRUARY 2014
JANUARY/FEBRUARY 2014
ASCB
NEWSLETTER
α
E-catenin actin-binding domain alters actin filament conformation and regulates binding of
nucleation and disassembly factors
S. D. Hansen, A. V. Kwiatkowski, Chung-Yueh Ouyang, HongJun Liu, S. Pokutta, S. C. Watkins,
N. Volkmann, D. Hanein, W. I. Weis, R. D. Mullins, and W. J. Nelson
α
E-catenin regulates transitions in actin organization between cell migration and cell–cell adhesion by
controlling barbed-end polymerization of unbranched actin filaments and inhibiting Arp2/3 complex and
cofilin regulation of actin filament branching and disassembly.
Mol. Biol. Cell 24 (23), 3710–3720
mTOR regulates phagosome and entotic vacuole fission
M. Krajcovic, S. Krishna, L. Akkari, J. A. Joyce, and M. Overholtzer
Phagosomes and entotic vacuoles harboring engulfed cells undergo an mTOR-regulated process of vacuolar
fission that distributes engulfed contents throughout lysosome networks. Amino acid recovery from engulfed
cells activates mTORC1 and rescues engulfing cells from the effects of amino acid starvation.
Mol. Biol. Cell 24 (23), 3736–3745
Cadherin-6B is proteolytically processed during epithelial-to-mesenchymal transitions of the
cranial neural crest
A. T. Schiffmacher, R. Padmanabhan, S. Jhingory, and L. A. Taneyhill
Cadherin-6B is rapidly depleted from
premigratory neural crest cells during
epithelial-to-mesenchymal transition (EMT),
suggestive of posttranslational mechanisms.
ADAM10, ADAM19, and
γ
-secretase cleave
cadherin-6B, and ADAM perturbation alters
the premigratory neural crest cell domain. The
study provides the first evidence for cadherin-
6B proteolysis in neural crest cells during EMT.
Mol. Biol. Cell 25 (1), 41–54
A conserved flagella-associated protein
in
Chlamydomonas
, FAP234, is essential
for axonemal localization of tubulin
polyglutamylase TTLL9
T. Kubo, H. Yanagisawa, Zhongmei Liu,
R. Shibuya, M. Hirono, and R. Kamiya
A novel axonemal protein, FAP234, of
Chlamydomonas is found to form a complex
with a tubulin-polyglutamylating enzyme,
TTLL9, and function in the stabilization and
intraflagellar transport of TTLL9. These proteins
are conserved in most ciliated organisms and
may be specialized for regulation of ciliary
motility.
Mol. Biol. Cell 25 (1), 107–117
The Editorial Board of
Molecular Biology of the Cell
has highlighted the following articles from
the December 2013 and January 2014 issues. From among the many fine articles in the journal,
the Board selects for these Highlights articles that are of broad interest and significantly advance
knowledge or provide new concepts or approaches that extend our understanding.
HIGHLIGHTS
from
MBoC
Natural Killer (NK) lymphocytes contain lysosome-related organelles known as lytic granules
that, upon formation of an immunological synapse (IS) with the target cell, polarize toward the
IS to deliver their contents to the target cell membrane. Tuli et al. (Mol. Biol. Cell 24, 3721–
3735) have identified a small GTP-binding protein, Arl8b, as a critical factor required for NK
cell– mediated cytotoxicity. Their findings indicate that Arl8b drives the polarization of lytic
granules toward the IS between an effector NK lymphocyte and the target cell. The left image is
a transmission electron micrograph of a control NK–target cell conjugate in which polarization
of lytic granules toward the IS is evident. In contrast, an Arl8b-silenced NK–target cell conjugate
shows a defect in polarization of lytic granules toward the IS (right). (Image: Amit Tuli and
Michael B. Brenner, Harvard Medical School)
NEAT1 long noncoding RNA regulates
transcription via protein sequestration within
subnuclear bodies
T. Hirose, G. Virnicchi, A. Tanigawa, T. Naganuma,
R. Li, H. Kimura, T. Yokoi, S. Nakagawa,
M. Bénard, A. H. Fox, and G. Pierron
Paraspeckles are subnuclear structures formed
around NEAT1 long noncoding RNA (lncRNA).
Paraspeckles became enlarged after proteasome
inhibition caused by NEAT1 transcriptional
activation, leading to protein sequestration
into paraspeckles. The NEAT1-dependent
sequestration affects the transcription of several
genes, arguing for a novel role for lncRNA in gene
regulation.
Mol. Biol. Cell 25 (1), 169–183
Distinct roles of cell wall biogenesis in yeast
morphogenesis as revealed by multivariate
analysis of high-dimensional morphometric
data
H. Okada, S. Ohnuki, C. Roncero, J. B. Konopka,
and Y. Ohya
To better define how cell wall structure affects
morphogenesis, the morphology of yeast cells
was analyzed quantitatively after treatment with
the three drugs that inhibit different aspects of
cell wall synthesis. These drugs induced both
similar effects, including broader necks and
increased morphological variation, and distinct
effects.
Mol. Biol. Cell 25 (2), 222–233
Centrosome-dependent asymmetric inheritance of the midbody ring in
Drosophila
germline stem
cell division
V. Salzmann, Cuie Chen, C.-Y. A. Chiang, A. Tiyaboonchai, M. Mayer, and Y. M. Yamashita
The midbody ring (MR) is asymmetrically segregated during asymmetric divisions of germline stem cells
(GSCs) in Drosophila. Male GSCs, which inherit the mother centrosome, exclude the MR, whereas female
GSCs, which inherit the daughter centrosome, inherit the MR. Moreover, stem cell identity correlates with
the mode of MR inheritance.
Mol. Biol. Cell 25 (2), 267–275
n
Depletion of the Smc5/6 complex leads to an abnormal chromosome structure, i.e., curly
chromatids with characteristic hypo-condensed centromeres. Immunofluorescence microscopy
of Smc5-depleted human RPE-1 cells typically reveals that topo II
α
, a main constituent of the
chromosomal axis scaffold, is depleted at centromeres and enriched at the distal chromatid arms.
This imbalanced distribution of topo II
α
creates an emblematic starburst-like figure at metaphase,
which underscores the significance of Smc5/6 in structural control of chromosomes. See Mol.
Biol. Cell 25, 302–317. (Image: Lina Marcela Gallego-Paez, The Cancer Institute, Japanese
Foundation for Cancer Research).
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