Related Experiment Video
Updated: Jun 17, 2026
09:20
Live Cell Response to Mechanical Stimulation Studied by Integrated Optical and Atomic Force Microscopy
Published on: October 4, 2010
Mg2+ modulates integrin-extracellular matrix interaction in vascular smooth muscle cells studied by atomic force
Andreea Trache1, Jerome P Trzeciakowski, Gerald A Meininger
1Department of Systems Biology and Translational Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, USA. trache@tamu.edu
Journal of Molecular Recognition : JMR
|January 6, 2010
Summary
Atomic force microscopy revealed that the binding strength between alpha5beta1 integrin and fibronectin increases with loading rates. Divalent cations like Mg(2+) and Ca(2+) modulate this interaction, impacting cell adhesion in dynamic environments.
Area of Science:
- Biophysics
- Cell Biology
- Materials Science
Background:
- Integrins are crucial cell surface receptors mediating cell-extracellular matrix interactions.
- Fibronectin (FN) is a key extracellular matrix protein involved in cell adhesion and migration.
- The mechanical properties of cell-matrix interactions are vital for cellular functions, particularly in dynamic environments like the vascular wall.
Purpose of the Study:
- To investigate the mechanical forces governing the interaction between alpha5beta1 integrin and fibronectin using atomic force microscopy (AFM).
- To quantify the effect of loading rates and divalent cations on the binding strength of single alpha5beta1-FN bonds.
- To understand how the ionic environment influences integrin-ligand interactions in vascular smooth muscle cells.
Main Methods:
- Utilized AFM with fibronectin-labeled probes to measure single alpha5beta1-FN bond rupture forces.
- Applied a physiological range of loading rates (100-10,000 pN/s) to probe bond dynamics.
- Quantified changes in binding energy and thermodynamic parameters by varying Mg(2+) and Ca(2+) concentrations.
Main Results:
- The force required to rupture a single alpha5beta1-FN bond increased twofold across the tested loading rates.
- Divalent cation concentrations (Mg(2+), Ca(2+)) significantly affected the thermodynamic parameters and binding energy of the alpha5beta1-FN interaction.
- Demonstrated that the mechanical parameters of integrin-FN binding are sensitive to the ionic environment and applied load.
Conclusions:
- The mechanical stability of alpha5beta1 integrin-fibronectin bonds is load-dependent and influenced by divalent cations.
- The extracellular ionic environment dynamically modulates the binding properties between integrins and the extracellular matrix.
- AFM provides direct measurements of these dynamic changes on live vascular smooth muscle cells, offering insights into mechanotransduction.
Related Concept Videos
01:17Intracellular Signaling Affects Focal Adhesions
Integrins act both as extracellular input receivers and as intracellular processing activators. As their name suggests, integrins are entirely integrated into the membrane structure. Their hydrophobic membrane-spanning regions interact with the phospholipid bilayer's hydrophobic region. These membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors. They activate intracellular response cascades when their effectors are bound and active.
Some...
Some...
01:24Overview of Cell-Matrix Interactions
The extracellular matrix or ECM holds cells together to form a tissue and allows the cells within the tissue to communicate. ECM comprises proteins such as fibronectin, collagen, laminin, etc. The most abundant protein in this space is collagen. Collagen fibers are interwoven with carbohydrate-containing protein molecules called proteoglycans. ECM allows cell migration and provides a structural scaffold at cell adhesion that anchors the cell when the extracellular matrix proteins interact with...
01:15Activation of Integrins
Integrins bind ligands and transmit information from outside the cell to inside or vice-versa through an "outside-in signaling" or "inside-out signaling."
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
In "outside-in signaling," external factors in the extracellular space bind to exposed ligand binding sites on integrins. This causes the inactive protein to undergo a conformational change to become active. Integrins are often clustered on the cell membrane. Repetitive and regularly spaced ligand binding events provide an effective stimulus.
01:13Cell-matrix's Response to Mechanical Forces
In animal cells, the extracellular matrix allows cells within tissues to withstand external stresses and transmits signals from the outside of the cell to the inside. The extracellular matrix is extensive, and its composition varies between different types of tissues. For example, the reticular fibers and ground substance make up the ECM in loose connective tissue, while collagen and bone minerals make up the ECM of bone tissue.
Anchoring junctions mechanically attach a cell to the...
Anchoring junctions mechanically attach a cell to the...
01:10Integrins
Animal and protozoan cells do not have cell walls to help maintain shape and provide structural stability. Instead, these eukaryotic cells secrete a sticky mass of carbohydrates and proteins into the spaces between adjacent cells. This network of proteins and molecules is called an extracellular matrix or ECM.
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...
Some ECM proteins assemble into a basement membrane to which the remaining components adhere. Proteoglycans typically form the bulk of the ECM while fibrous proteins, like collagen,...