Our
Extracellular Matrix is huge part of our bodies’ tissues. Although it was
thought of as a collection of non-living materials surrounding the cells that
just took up space, it is quite the opposite. Since 1975, we have
discovered that the Extracellular Matrix does much more than just take up
space. It has many important functions
including providing structural support, guiding cell movement, and determining
the look and function of tissues.
The Extracellular Matrix provides
structural support for the cells within tissues. It does this because of its lattice
structure. This lattice, or net-like,
structure is made up of many things, but the main and most common ingredients
of the structure are two fibrous proteins.
These two fibrous proteins are called collagen and laminin. The main backbone is the collagen which
creates something similar to a grid and laminin follows up and fills in the some
of the empty spaces creating a net that is hard for the cells to slip through.
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| Integrin going from non-active to active state due to Talin |
As I have said, the Extracellular
Matrix is very dynamic. Instead of just
surrounding the cells, it is constantly undergoing changes. This is mostly due to fibroblasts creating
more fibrous proteins to maintain and adapt the Extracellular Matrix to the tissue’s
needs. Other than this, the Extracellular
Matrix is dynamic in that it helps and guides cell movement. It
does this with integrins, a transmembrane protein that links the extracellular
matrix to the cells in the tissue.
Generally this happens when Talin inside the cell activates the two
tails of the integrins allowing it to bind with RGD loops. These RGD loops are usually found in
Fibronectin. By connecting,
disconnecting, and then reconnecting again with the RGD groups; a cell can make
its way across the Extracellular Matrix.
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| Proteoglycan Complex |
Another
one of the many important functions of the Extracellular Matrix is being able
to define the tissue it resides in. For
example, in bones, the Extracellular Matrix is mineralized creating the hard
tissue we need to create a sturdy skeleton.
However, in our eyes we need the Extracellular Matrix to create a
different kind of tissue. We need the Extracellular
Matrix to create a tissue that will be more like a gel and that is exactly what
it does. It creates a tissue that is
gel-like and contains a large concentration of water. This watery Extracellular Matrix is due to
more Proteoglycans being produced in the tissue which are able to transport and
contain water.
These functions of the Extracellular
Matrix just go to show that the Extracellular Matrix is more than just a
cluster of materials used to occupy extra space in tissues. They allow cells to move, create net-like
structure to aid in development, and are able to change and adapt their
respective tissue to excel in its location of the body.
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