TY  - GEN
N2  - In this study I investigated the mechanisms of clustering of the apoptosis receptor CD95
after induction with its ligand and the oligomerization level before induction. Previous
studies demonstrated that receptor clustering is an essential part in apoptosis signaling.
Mostly using biochemical methods and nuclear magnetic resonance the essential role of
various mechanisms in receptor clustering could be shown, such as lipid raft localization of
the receptor, clustering via the receptor death domain and internalization. An oligomerization
of receptors before induction via a so called pre-ligand assembly domain could be
shown at high concentrations, so that typically the receptor is assumed to be trimeric
before induction. Moreover a consistent model of the role of all mechanisms in different
cell types and direct observation on the plasma membrane is still missing. Therefore
I investigated receptor clustering in single living cells on the cell membrane using microscopy.
In particular I quantified intensities to correlate with the number of molecules.
and studied receptor clustering by dynamics measurements using fluorescence recovery
after photobleaching. I observed that receptor clustering is concentration dependent and
in HeLa at high receptor concentrations the ligand as only crosslinking mechanism yields
mean clusters size of seven molecules. Death domain assembly and lipid raft localization do not effect clustering in this cell type. At physiological expression levels the pre-ligand
assembly shows an oligomer distribution with an eminent part of monomers or dimers.
By knockdown of the receptor the distribution can be pushed to monomers. I made a
consistent study for the type II cell line HeLa, considering many proposed clustering
mechanisms and showed that ligand binding alone is a strong mechanism that can lead
to high levels of clustering. I propose a model where the receptor is present as monomers
or dimers at physiological concentrations in the absence of induction.
ID  - heidok13904
UR  - https://archiv.ub.uni-heidelberg.de/volltextserver/13904/
TI  - Mechanisms of CD95-Clustering
Y1  - 2012///
AV  - public
A1  - Berndt, Johanna
CY  - Heidelberg
ER  -