Cell adhesion mediated by the Integrin VLA-4 [Elektronische Ressource] / presented by Julia Schmitz

Cell Adhesion mediated by the Integrin
VLA-4
Julia Schmitz
Munich 2008Cell Adhesion mediated by the Integrin
VLA-4
Julia Schmitz
Dissertation
Faculty of Physics
Ludwig{Maximilians{University
Munich
presented by
Julia Schmitz
born in
Gr afel ng
May 30th, 2008
MunichFirst referee: Dr. Kay-Eberhard Gottschalk
Second referee: Prof. Dr. Joachim R adler
Date of the defense: July 25th,.2008To my family and friends: Thank you!Contents
Zusammenfassung x
Abstract xi
1 Introduction 1
1.1 Extravasation of Lymphocytes . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Adhesion Cascade . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1.2 Cellular Adhesiveness . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Integrins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.2 Activation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.3 Single-Molecule Force Spectroscopy . . . . . . . . . . . . . . . . . . . . . . 14
1.3.1 Atomic Force Microscope . . . . . . . . . . . . . . . . . . . . . . . . 14
1.3.2 Forced Unbinding of Single Molecules . . . . . . . . . . . . . . . . . 15
2 The Mechanics of Cellular Adhesion Receptors 20
2.1 Paxillin Association with the Cytoplasmic Tail regulates Adhesion Strength-4
ening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.2 The Mechanics of Transmembrane Receptors governs Cell Adhesion . . . . 21
2.3 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.4 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
-Dependent Adhesion Strengthening under Mechanical Strain is regu-4 1
lated by Paxillin Association with the -cytoplasmic Domain. . . . 244
The Viscoelasticity of Membrane Tethers and its Importance for Cell Adhesion. 37
Mechanical Regulation of Cell Adhesion . . . . . . . . . . . . . . . . . . . 65
3 Activation of the Integrin VLA-4 by the Chemokine SDF-1 98
3.1 Chemokine-Triggered Mechanical Activation of the Integrin VLA-4 . . . . 98
3.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.3 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Chemokine-Triggered Modulation of Lymphocyte Adhesion by a Mechanical
Integrin Activation . . . . . . . . . . . . . . . . . . . . . . . . . . . 100Contents vi
4 Single Molecules and Multiple Bonds 127
4.1 Single-Molecule Properties and Cell Adhesion in the Shear Flow . . . . . . 128
4.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
4.3 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Linking Single Integrin Bond Properties to Cell Adhesiveness at Rapid Con-
tacts generated under External Forces . . . . . . . . . . . . . . . . 129
5 Opto-Mechanical Studies of Cell Adhesion 157
5.1 The Power of Opto-Mechanical Approaches for the Investigation of Cell
Adhesion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
5.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
5.3 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Single-Tether Opto-Mechanical Investigation of Cell Adhesion . . . . . . . 159
6 Other Projects: The Mechanics of Impacting Nano-Mechanical Single-
Electron-Transistors 173
6.1 Q-factor and Dissipation of Impacting MSETS . . . . . . . . . . . . . . . . 174
6.2 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
6.3 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Self-excitation of a Nano-Mechanical Single-Electron Transistor at 4 Kelvin 175
7 Outlook 181
A Appendix A: The Kinetics of Cell Adhesion extrapolated from Single
Molecule Properties 183
A.1 Bond Formation in the Atomic Force Spectroscopy . . . . . . . . . . . . . 183
A.2 Bond F in the Flow Chamber . . . . . . . . . . . . . . . . . . . . 184
B Appendix B: The Force-Distance Relationship of a Kelvin Body 185
Glossary 187
Acknowledgements 203
Curriculum Vitae 204List of Figures
1.1 The experimental setup: The lymphocyte presenting the integrin VLA-4
was immobilised on the cantilever of an AFM. The substrate was coated
with the isolated integrin ligand, VCAM-1. . . . . . . . . . . . . . . . . . . 2
1.2 The recruitment of lymphocytes from the blood stream: The initial rolling
process slows the lymphocytes down, so that they can react to in ammatory
signals displayed on the endothelium. In the case of injury or in ammation
in the adjacent tissue, the lymphocytes start to adhere strongly to the vessel
wall and extravasate into the tissue ( gure taken from ref. [1]). . . . . . . . 3
1.3 The cellular anchorage of integrins: Integrins can be either freely di using
in the membrane (middle), attached to the cytoskeleton (left) or clustered
by intracellular proteins (top). But the nano-environment also a ects the
receptor anchorage: receptors located in lipid rafts (bottom) or in membrane
areas with many actin-binding proteins (right) display a sti er anchorage
than those in other membrane compartments ( gure taken from ref. [2]). . 5
1.4 The structure of the integrin : The and subunits are depicted inV 3
blue and red, respectively, and the domains are indicated. The head of the
heterodimer can bend towards the membrane at the genu (left; gure was
taken from reference [3]). . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.5 The conformational equilibrium of integrins: The bent conformation shows
low a nity ( left), the extended conformation with closed head intermediate
(centre) and the extended conformation with open head high a nity for the
ligand (right). The and