Integrins

Integrins

Ingber explained integrins and their role in tensegrity in a NIH Public Access Author Manuscript, 2009. The article was then published in Journal Bodywork Movement Therapy. He wrote:

When we move our muscles and bones, we add mechanical energy to this mechanical equilibrium that already exists in our bodies. This results in stress channeling through the loadbearing elements, which induces physical distortion of the living tissues that comprise these organs. To understand how this physical process might impact human health, we must take into account that living organisms, such as man, are constructed from tiers of systems within a system within a system. Each organ, such as a whole muscle, is constructed from tissues (e.g., muscle fibers, endothelium, tendon, nerve), which are composed of living cells that are linked together by extracellular matrix (ECM) scaffolds. Cells adhere to these ECMs (composed of collagens, glycoproteins, and proteoglycans) via binding of specific cell surface receptors, known as “integrins”.

Integrins span the cell’s surface membrane and form a multi-molecular bridge to the internal “cytoskeleton” of the cell – an internal molecular framework composed of actin microfilaments, microtubules and intermediate filaments that gives shape to the cell. Many of the actin filaments closely associate with myosin filaments, which slide along each other, shorten and thereby, generate mechanical tension that is distributed to all elements of the cell, as well as to the external ECM, via their integrin contact points. Importantly, this is observed in the cytoskeleton of all cells (e.g., epithelial cells, nerve cells, immune cells, bone cells and fibroblasts) and not just in muscle cells.

The tensional forces that are generated in contractile acto-myosin filaments in the cytoskeleton are resisted by the cells external tethers to the ECM, and by other cytoskeletal filaments that resist being compressed (e.g., microtubules, cross-linked actin filament bundles) by these inward-directed forces. For this reason, all cells in our tissues also exist in a state of isometric tension, and it is because of this internal prestress that surgeons need to suture together wounds when they incise living organs. Thus, tensegrity is used to stabilize the shape of living cells, tissues and organs, as well as our whole bodies.

Animated Simulation of Integrin and Tensegrity

See http://www.childrenshospital.org/research/cell_tensegrity/index.html

Links and References

The text above is from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2614693/pdf/nihms64931.pdf