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Undergraduate education: Study of Biological Sciences
with focus on Biochemical Science.
21st October 2005 MSc in Biology at the University of
L’Aquila (Italy), (Title: “The Effect of Cysteamine on
Activity of Detoxifying and Antioxidative Enzymes in
Vanin-1 Null-Mice).
Statement of research interests: Potential mechanisms of
G-protein coupled receptor-mediated cell migration. The
critical function of chemokines and their receptors in
cell migration was first described in inflammatory
reactions. Evidences accumulated over the years revealed
that essentially all leukocyte trafficking during
development, inflammation and homing is regulated by the
chemokine system. In general, inflammatory chemokines
attract leukocytes to sites of injury, whereas homeostatic
chemokines recruit immune cells to lymphoid organs and
mediate their development though multiple reactions
between chemokines and their receptors. In addition
chemokines can mediate cell migration during embryonic
development and tumor metastasis. Cell migration is
initiated by the binding of a chemokine (agonist) to a
seven transmembrane domain receptor, also called G-protein
coupled receptor (GPCR). Chemokine receptors share highly
conserved domains, such as the DRYL/IAIV sequence at the
N-terminus of the second intracellular loop and a CxNPxxY
sequence in helix seven. Despite their structural
similarity and the coupling to the same type of
Gi-proteins, the chemokine receptors activate common and
specific signal transduction pathways leading to diverse
responses. A possible explanation for these observations
is that GPCR can form oligomers which couple selectively
to scaffolding molecules. In line with such view it was
shown that chemokine receptors are present at the plasma
membrane as homo- or heterodimers. The investigations
shall focus on two aspects of chemokine receptor-mediated
cell migration. 1) The spatio-temporal activation of
G-protein coupled receptors in moving cells. How is the
receptor activity controlled in polarized cells, which
migrate through a shallow gradient of chemoattractant?
Using receptors tagged with fluorescent probes it should
be possible to monitor their activation states at
different sites of a cell. Recently it was shown that
intramolecular fluorescence resonance energy transfer
(FRET) of GFP/YFP tagged GPCR reliably reports the
activation state with kinetics comparable to wild type
molecules. The FRET studies were performed with the
Gi-coupled 2-adrenergic receptor (2AR). In
the host laboratory critical preliminary experiments have
been performed, which indicated that the 2AR can
induce cell migration and the constructs may be used as a
model to reveal the activation state of
chemotaxis-mediating receptors. 2) Cell migration is
accompanied by a profound remodeling of the actin
cytoskeleton. Several lines of evidence indicate that
RhoGTPases are critical upstream regulators of this
process. While investigating chemokine receptor-mediated
cell migration the host laboratory observed that the
RhoGTPase specific GTP exchange factor P-Rex1 becomes
rapidly and transiently phosphorylated. The kinetics of
P-Rex1 phosphorylation are in agreement with the protein
being involved in rapid Rho-GTPase activation and actin
polymerization. Preliminary data suggest the presence of
multiple phosphorylation sites which could affect activity
and localization of the protein. My investigations shall
disclose the physiological role of the different
phosphorylation events and to delineate the pathways which
lead to the posttranslational modifications. In addition,
modified proteins will be generated to use FRET to
investigate the involvement of P-Rex 1 in
chemokine-receptor stimulated cell migration. The results
may provide new insights on the regulation of leukocyte
trafficking, a critical event during beneficial and
malignant inflammatory responses. Comparison of
chemokine-stimulated cell migration by different receptors
and distinct cellular systems may eventually lead to
biomarkers that are specific for some, but not all
chemotactic pathways, and may be used to selectively
interfere with cell trafficking.
Expectations from Integramm: I'm convinced, that the
well supervised and individually tailored research and
training program of the International Graduate Program in
Molecular Medicine will provide me an excellent
environment to perform my PhD work and the international
setting of the Network of Excellence will be highly
stimulating for my future career.
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