Cell News 3/2013
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Meeting report on the 12th workshop on ’Cell biology of viral
infections’ ’Cell Biology of Metabolic Processes’
Claudia Claus
1
, Steeve Boulant
2
1
Institute of Virology, University of Leipzig
2
Department of Infectious Diseases, Cellnetworks and DKFZ, University Heidelberg
The 12th Workshop „Cell Biology of Viral Infections“ of the So-
ciety for Virology (GfV) took place in Deidesheim, December 4th
– 6th 2013, and was centered around “Cell Biology of Metabolic
Processes”. Metabolism is an umbrella term for a complex net-
work of (bio)chemical reactions embedded in various organelles
of the cell. Metabolic processes convert molecules in a step-wise
manner into metabolic intermediates and finally into metabolic
precursors. They are either oxidised into ATP, the energy currency
of all cells, or used as building blocks for macromolecules such
as amino acids, lipids, and nucleotides. These building blocks are
not only required for cellular growth and maintenance, but also
for viral replication and assembly of new viral progeny. With the
exception of the family Herpesviridae with their rather large co-
ding capacity, viruses lack metabolic enzymes. Hence many viru-
ses have developed various means to manipulate cellular meta-
bolism such that viral replication can be ensured and optimised
[1], [2]. This close interconnectivity of cellular and viral metabo-
lism sets the ground for the exploitation of specific metabolites
as new and promising drug targets [3]. Metabolic approaches
can also be used to visualise distinct parts of the virus life cycle,
e. g. through application of fluorescently labelled lipids. Some of
these virological aspects parallel other patho-physiological con-
versions of cellular metabolism such as cancer.
The workshop “Cell Biology of Viral Infections“ was originally es-
tablished by the GfV to promote exchange and lively discussions
between virologists and cell biologists. The issue on “Cell Biolo-
gy of Metabolic Processes” especially bridges virology-centered
with cell biology-related research aspects and is in line with the
previous topics of this rather informal workshop. The workshop
once more took place on the estates of the famous winery Bas-
sermann-Jordan in Deidesheim and was again co-sponsored by
the GfV and the DGZ. Four cell biologists gave excellent talks
during the keynote sessions and provided insights into their exci-
ting fields of research. These sessions were followed by oral pre-
sentations from mostly young scientists undergoing their post-
graduate studies covering diverse virological research aspects.
Eric Chevet, INSERM scientific director at the University of Bor-
deaux, France, is an expert on the role of endoplasmic reticulum
in stress signalling and proteostasis. With his talk on "Control of
Endoplasmic Reticulum homeostasis in cancer" Dr. Chevet int-
roduced us to the so-called Unfolded Protein Response (UPR),
which is triggered upon accumulation of unfolded proteins
within the endoplasmic reticulum. This response is mainly me-
diated by three transmembrane proteins: PERK, ATF6 and IRE1.
His talk mostly focused on the protein IRE1, which constitutes a
key protein regulating the balance between cytoprotection and
induction of apoptosis during proteotoxic stress. Survival is fa-
voured by inducing autophagy.
Nicholas Ktistakis, from the Babraham Institute in Cambridge
University, UK, focuses his research on the signalling events and
intermediate structures, which eventually end in autophagoso-
me formation. Autophagosomes are the executioners of auto-
phagy, which is triggered during certain developmental stages,
stress, starvation, and in response to an infection with viral
and bacterial pathogens. They are double-membrane structures
and deliver material to lysosomes for degradation. Prof. Ktista-
kis gave a talk on lipid-based signal transduction entitled “The
role of a simple phosphoinositide lipid (PI3P) in the regulation of
autophagy and in activation of mTOR”. He explained the para-
dox role of PI3P (phosphatidylinositol 3-phosphate) in nutrient
sensing. In the absence of amino acids and growth signals, the
protein kinase mTOR (mammalian target of rapamycin), a mas-
ter regulator of cell growth, is inactive, and PI3P contributes to
autophagy induction. Unexpectedly, in the presence of nutrients,
PI3P appears as a positive regulator of mTOR and subsequently
in the initiation of cell growth. Prof. Ktistakis illustrated how his
group contributed to the characterisation of omegasomes, which
represent a PI3P-enriched ER-subdomain, where at least some
autophagosomes are formed. In this omega-like shape mem-
brane structures, PI3P acts as a key player in autophagosome
formation and membrane regulation during the early steps of
autophagy.
Jean-Ehrland Ricci, is a young team leader at the French Natio-
nal Institute of Health and Medical Research (INSERM) in Nice,
France. His laboratory investigates the role of metabolic proces-
ses in apoptosis. His entertaining and illustrative talk on “Me-
tabolic control of cell death: relation to cancer and anti-cancer
immune response“ gave an impression on how effective the com-
bination of chemotherapy with metabolic inhibitors is in treating
cancer. Dr. Ricci gave a general overview on apoptosis induction
by extrinsic and intrinsic mechanisms; he especially focused on
how much apoptosis and metabolism are intertwined. Further-
more, tumour cell metabolism can be connected with an antitu-
mour immune response. In this context the outcome of chemo-
therapy can be improved and the problem of chemoresistance
in cancer cells could be reduced. He highlighted the importance
of cell-induced death pathways (apoptosis vs. necrosis) during
MEETING REPORT
