Cell News 01/2017
15
Spindle Length and Shape:
How Geometry Arises from Molecular Interactions
Simone Reber
ABSTRACTS CHAIRS AND SPEAKERS
IRI for the Life Sciences, Humboldt-Universität zu Berlin
Each cellular organelle carries out a distinct function, which
is not only related to its molecular composition, but in many
cases also to its size and shape. This is particularly evident in
the case of the metaphase spindle. While approaching near to
complete proteomic parts lists of cellular organelles, mech-
anisms that control emergent properties such as shape and
size remain poorly understood. By combining biochemistry,
biophysics,
in vitro
reconstitution assays and theory, we aim
to uncover how molecular machines that act at the Angstrom
scale are coordinated in space and time to create physiological
structures in the micrometer scale that enable cell function.
The syndecan-syntenin pathway
in exosome biogenesis and uptake
Pascale Zimmermann
Centre de Recherche en Cancérologie de Marseille (CRCM),
Inserm UMR1068, CNRS UMR7258, Aix-Marseille Université
& Institut Paoli-Calmettes, 27 boulevard Leï Roure, BP 30059,
13273 MARSEILLE CEDEX 09, France
and
K.U.Leuven, Faculty of Medicine, Department Human Genetics,
Laboratory for Signal Integration in Cell Fate Decision, Here-
straat, 49 O&N1 box 602, B-3000 Leuven, Belgium
Secreted vesicles carry complexes messages (proteins, lipids
and nucleic acids) and appear important for tissue homeosta-
sis and intercellular communication. Moreover they recently
gained in interest for medicine. They represent potential sourc-
es of biomarkers that can be collected from body fluids and,
by disseminating pathogenic proteins, might also participate
in systemic diseases like cancer, atherosclerosis and neurode-
generation. The mechanisms controlling the biogenesis and the
uptake of secreted vesicles are poorly understood, precluding
rational intervention.
Some of these vesicles originate from endosomes and are
called 'exosomes'. Here, we will recapitulate recent insight on
the role of the syndecan heparan sulphate proteoglycans, the
small intracellular adaptor syntenin and associated regulators
in the biogenesis and loading of one class of exosomes. We
will also present data supporting a role for syndecan-syntenin
in exosome uptake. These studies highlight molecular mecha-
nisms supporting cell-cell communication via secreted vesicles,
both at the level of signal emission (exosome biogenesis) and
signal reception (exosome uptake).
fusion during development, we have analyzed genetic loss-of-
function mutants on ultrastructural level and performed classic
epistasis experiments. Our data indicate that myoblast fusion
is a tightly controlled mechanism involving multiple layers of
coordinated Arp2/3-dependent F-actin polymerization to bring
plasma membranes in close apposition and to induce fusion
pore formation.
