Dipl.-Ing. Christoph Winkler A Close Look at Actin Driven Movement

¨ FUR
¨ MATHEMATIK
FAKULTAT
Dekan Univ.–Prof. Dr. Harald Rindler
Einladung zur o¨ffentlichen Defensio von
Dipl.-Ing. Christoph Winkler
Thema der Dissertation:
A Close Look at Actin Driven Movement: From
Image Analysis to Simulation
Abstract: The actin cytoskeleton capacitates many eukaryotic cells to perform individual
locomotion in such diverse as well as important processes as, for instance, the organization
of the embryo, the immune interaction and the proliferation of tumors. It is built up by a
meshwork of long, thin rods of concatenated actin monomers whose formation and interplay
with one another and other cell compartments is regulated by specific proteins. The mostly
crawling locomotion of individual cells is often performed with a sheet-like lamellipodium,
a flat but wide structure wrapped by the cell membrane and filled with a dense actin
filament network that pushes the whole cell. However, the actin cytoskeleton can also be
abused by infections for the transportation inside of cells. Although most proteins involved
in these locomotion processes have been identified, their exact organization and interaction
remain unknown.
The actual structure of the lamellipodium’s actin filament meshwork is investigated with
an algorithm to identify individual filaments in three dimensional electron tomo-graphy
pictures. The filaments are tracked with a localized Radon transform and the obtained
information does not only allow for averaged data such as angular distributions or actin
density but moreover delivers insights into the filaments’ length and bending.
Microscopic stochastic simulations consisting of a set of growing and proliferating filaments
are used to understand the intracellular movement of a specific virus and the temporal
evolution of lamellipodia. In the case of the virus, characteristic movement patterns are
reproduced and indications for the nature of the filament-virus-interplay are found. For
lamellipodia a surface finite element method is used to describe the deformable membrane
and a band of densely packed membrane proteins that interact with the actin filaments.
The simulation exhibits the typical organization of lamellipodia and in particular is able
to preserve their flatness without geometric restrictions.
Pr¨
ufungssenat:
Univ. Prof. Dr. Josef Hofbauer(Vorsitz)
(Universit¨at Wien)
Univ.-Prof. Dr. Christian Schmeiser
(Universit¨at Wien)
Prof. Dr. Angela Stevens
(Universit¨at M¨
unster)
Univ.Prof. Ulisse Stefanelli
(Universit¨at Wien)
Zeit: Mittwoch, 29. April 2015, 15:00 Uhr
Ort: Fakult¨at f¨
ur Mathematik, Besprechungsraum 09. Stock, Oskar-Morgenstern-Platz 1

Download Report