| Poster, Friday, 19:00 |
|
|
|
| Manipulation of cellular mechanics
Anna Pietuch, Andreas Janshoff
Georg August University of Göttingen,
Biophysical Chemistry Group, Tammanstraße 6, 37077 Göttingen,
Germany |
|
|
| Contact:
| Website |
|
|
The apical surface of epithelial cells is structured by microscopic cellular
membrane protrusions the so-called microvilli. Stabilized by dense actin
bundles, microvilli are believed to be involved in a number of cellular
processes encompassing absorption, secretion, and mechanotransduction [1].
Ezrin, a membrane-microfilament-anchor of the ERM-(ezrin/radixin/moesin)-protein
family, has major contribution in structural organization and stabilization
of the microvilli. It is believed that the ezrin binding to the plasma
membrane is mediated by the phospholipid phospatidylinositol(4,5)-bisphospate
(PIP2) [2]. Here we used two different methods to apply changes
on the microvillus architecture. We deplete cholesterol from the plasma
membrane by adding methyl-ß-cyclodextrin (MBCD) and microinject the
PIP2 blocking agent neomycin.
Cholesterol depletion and therefore destruction of lipid raft domains
delocalizes PIP2, resulting in an uncoupling of the plasma membrane
from the underlying cortical cytoskeleton by altering the association between
ezrin and the plasma membrane. The alternative administration of cortical
actin modifying substances into the cell is achieved by microinjection.
By microinjecting neomycin, which binds selectively PIP2, the
coupling of the plasma membrane to the actin cytoskeleton can be switched
off. This approach allows manipulating single cellular mechanics by comparing
directly the untreated neighboring cells to the affected one.
Today it is possible to investigate local cellular elastic properties
under almost physiological conditions using the Atomic Force Microscope
(AFM). By performing force indentation curves on local areas on a cell
surface the use of contact mechanic models (Hertz and liquid droplet) provides
information about the elastic properties of cells [3]. By modifying the
cortical cytoskeleton underlying the plasma membrane, it is possible to
investigate its importance for the mechanical behavior of a cell.
Fig. 1: AFM measurements of MDCK II cells. A: height image of living
untreated MDCK II cells. B: Mechanical parameter (Young modulus E, area
compressibility modulus Ka and membrane tension sigma) of MDCK
II cells with cholesterol depleting MBCD for 0h, 1h and 2h. C: Force curves
with fit before and after 1h treatment with MBCD.
| [1] |
|
S. Weinbaum, P. GuoL. You, Biorheology.
38 (2–3): 119–42 (2001). |
|
|
|
| [2] |
|
M. Edidin, Annu Rev Biophys Biomol
Struct. 32: 257–83 (2003). |
|
|
|
| [3] |
|
M. J. Rosenbluth, W. A. Lam, D. A. Fletcher,
Biophysical Journal, 90: 2994–3003 (2006). |
|
