Biology Reference
In-Depth Information
For several years, we have established SCFS as a tool to quantify cell
adhesion. An important improvement of the experimental setup was the
development of a commercially available AFM that features an enhanced
pulling range (>100 μm), precision (
$
Distance ≈ 0.1nm) and sensitivity
$
(
Force ≈ 5 pN) such as required to conduct cell-cell adhesion measurements.
61
This optimized setup further allowed probing adhesion over a broad range of
detachment forces, from single-molecule interactions to high forces exerted
by more complex adhesion sites.
Moreover, by combining SCFS with
advanced optical microscopy techniques, a better control of the experiment
was provided. Using this setup, adhesion of gastrulating zebraish cells to
ibronectin-coated surfaces could be quantiied and allowed characterizing
the role of Wnt11 in modulating integrin-mediated adhesion.
62
In a similar
setup, the impact of Wnt11 on intercellular adhesion of gastrulating
zebraish cells was studied. Wnt11 was found to modulate E-cadherin-
mediated adhesion via a Rab5-dependent mechanism.
63
Furthermore, it
was determined whether the adhesion of germ layers cells contribute to the
gastrulation of zebraish embryos.
38
Fundamental mechanisms underlying
cellular sorting during gastrulation could be experimentally veriied, and
the contribution of cell adhesion and cell cortex tension to cell sorting could
be deciphered. In another study, SCFS was applied to characterize integrin
A
30
B
1
-mediated adhesion to nanopatterned collagen type I matrices. Because
of the high force resolution of the setup, it could be resolved that integrin
receptors cooperatively assemble to higher-order adhesion structures to
enhance cell adhesion.
2
In two further studies, the contribution of galectins
to the adhesion of epithelial Madin-Darby canine kidney (MDCK) cells to
ECM proteins was quantiied. It was found that early adhesion of MDCK cells
to laminin-111 was
integrin-independent and mediated by
carbohydrate
interactions and galectins. When adhering to collagen type I and IV, MDCK
cells frequently entered an enhanced adhesion state which was characterized
by signiicantly increased detachment forces. Although MDCK cell adhesion
was mediated by integrins, adhesion enhancement was observed for those
cells in which a certain member of the galectin family, galectin-3, has been
depleted. It was proposed that galectin-3 inluences integrin-mediated
adhesion complex formation.
62
In another example, the tyrosine kinase
BCR/ABL, a hallmark of chronic myeloid leukaemia, was found to increase
the concentration of integrin
36,37
1
-subunits on the cell surface and to enhance
adhesion of leukemic cells to ECM proteins that have been secreted by bone
marrow stromal cells.
B
34
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