EXTRACELLULAR MATRIX

In biology, 'extracellular matrix' ('ECM') is the extracellular part of animal tissue that usually provides structural support to the cells in addition to performing various other important functions. Extracellular matrix is the defining feature of connective tissue in animals.
Extracellular matrix includes the interstitial matrix and the basement membrane.^[1] Interstitial matrix is present between various cells (ie. in the intercellular spaces) whereas basement membranes are sheet-like depositions of ECM on which various epithelial cells rest.

Contents

Components

Importance of ECM

Adhesion to matrix

References

External links

Components

The main components of ECM are various glycoproteins, proteoglycans and hyaluronic acid. In most animals, the most abundant glycoproteins in the ECM are collagens. In fact, collagen is the most abundant protein in the human body^{[2] [3]} and accounts for 90% of bone matrix protein content.^[4]
ECM also contains many other components: proteins such as fibrin, elastin, fibronectins, laminins, and nidogens, and minerals such as hydroxylapatite (in bone), or fluids such as blood plasma or serum with secreted free flowing antigens.

Importance of ECM

ECM, due to its diverse nature and composition, can serve many functions, such as providing support and anchorage for cells, segregating tissues from one another, and regulating intercellular communication. The ECM regulates a cell's dynamic behavior. Hyaluronic acid provides lubrication in joint spaces.
Formation of the exracellular matrix is essential for processes like growth, wound healing and fibrosis. An understanding of ECM structure and composition also helps in comprehending the complex dynamics of tumor invasion and metastasis in cancer biology as metastasis often involves the destruction of extracellular matrix. ^[5]
In addition, ECM sequesters a wide range of cellular growth factors, and acts as a local depot for them. Changes in physiological conditions can trigger protease activities that cause local release of such depots. This allows the rapid and local growth factor-mediated activation of cellular functions, without de novo synthesis.

Adhesion to matrix

Many cells bind to components of the extracellular matrix. This cell-to-ECM adhesion is regulated by specific cell surface cellular adhesion molecules (CAM) known as integrins. Integrins are cell surface proteins that bind cells to ECM structures, such as fibronectin and laminin, and also to integrin proteins on the surface of other cells.

References

1. Kumar, Abbas, Fausto; ''Robbins and Cotran: Pathologic Basis of Disease''; Elsevier; 7th ed.
2. Gloria A. Di LulloDagger , Shawn M. Sweeney, Jarmo Körkkö, Leena Ala-Kokko, and James D. San Antonio; Mapping the Ligand-binding Sites and Disease-associated Mutations on the Most Abundant Protein in the Human, Type I Collagen; ''J. Biol. Chem.'', Vol. 277, Issue 6, 4223-4231, February 8, 2002
3. Karsenty G, Park RW.; Regulation of type I collagen genes expression.; ''Int Rev Immunol.'' 1995;12(2-4):177-85.
4. Britt Kern, Jianhe Shen, Michael Starbuck, and Gerard Karsenty; Cbfa1 Contributes to the Osteoblast-specific Expression of type I collagen Genes; ''J. Biol. Chem.'', Vol. 276, Issue 10, 7101-7107, March 9, 2001
5. L. A. Liotta, K. Tryggvason, S. Garbisa, Ian Hart, C. M. Foltz & S. Shafie; Metastatic potential correlates with enzymatic degradation of basement membrane collagen; Nature 284, 67 - 68 (06 March 1980).

External links

★

★ ANAT3231 Lecture 08 Extracellular Matrix - Lecture about extracellular matrix from UNSW Cell Biology website.

★ Extracellular matrix: review of its roles in acute and chronic wounds

★ Usage of Extracellular Matrix from pigs to regrow human extremities

★ "The Extracellular Matrix of Animals", from Chapter 19 of ''The Molecular Biology of the Cell'', 4th edition, Alberts ''et al.''