Animal cell culture lecture -3- Cell – matrix interaction By: Saib H. Al Owini From
Dec 23, 2015
Cell – matrix interaction
• The extracellular matrix, where most animal cells in tissues are embedded, fills the spaces between cells and binds cells and tissues together.
• The wide matrix in CT• May be calcified, transparent, liquid,• Matrix form basal lamina between CT and
Epith.
• Basal laminae is a sheetlike extracellular matrix that supports epithelial cells and surrounds muscle cells, adipose cells, and peripheral nerves.
• Matrix play more active and complex role in regulation the behavior of cells that contact it.
• Proliferation , migration, development, shape
and function.
• Extracellular matrix is made and oriented by cells within it.
• Extracellular matrices are composed of :
1- A gel-like polysaccharide ground substance—a design basically similar to that of plant cell walls.
2-Tough fibrous proteins .
1 -GlycosaminoglycansGAGs
• GAGs, are gel-forming polysaccharides of the extracellular matrix that consist of repeating units of disaccharides.
• Five major types, have Differences in: ( sulphate group and its location, linkage type).
GAGs+protein=
• Proteoglycans are proteins linked to glycosaminoglycans and consist of up to 95% polysaccharide by weight.
• Eg ( aggrecan lage , decorine small)
• A number of proteoglycans interact with hyaluronan to form large complexes in the extracellular matrix.
GAGs function
1- GAGs act as filter gel• Heparan sulphat proteoglycans golmerular basal
lamina filter
2-Bind to growth factors AS stimulation of ( FGF)
3- Regulation of secretory proteins by :( immobilize, delayed, prolong action )
2-Tough fibrous proteins.
• Collagen, the major structural protein of the extracellular matrix, is the single most abundant protein in animal tissues.
• The collagens are a large family of proteins containing at least 27 different members
Elastin
• Elastic fibers, found in connective tissues, are particularly abundant in organs that regularly stretch and then return to their original shape.
• Elastin is cross-linked into a network by covalent bonds formed between the side chains of lysine residues and the protein that elastic fibers are principally composed of.
Matrix adhesion proteins
- The final class of extracellular matrix constituents, are responsible for linking the components of the matrix to one another and to the surfaces of cells.
• Fibronectin is the principal adhesion protein of connective tissues
2 -Laminin ,
• BASAL LAMINA : • Flexible thin 40-120 nm • Influence cell metabolism • Induce cell differentiation • From the cells which set on . • tow layer ( from collagen , perelecan –
heparan sulphate proteiglycan-, laminin entactin )
• Laminin is the principal adhesion protein of basal laminae.
• Entactin, another adhesion molecule that is associated with laminins, binds to type IV collagen.
integrins
• Integrins are the major cell surface receptors responsible for the attachment of cells to the extracellular matrix.
• In addition to attaching cells to the extracellular matrix, integrins serve as anchors for the cytoskeleton.
integrins
• Focal adhesions are a type of cell-matrix junction that attach a variety of cells, including fibroblasts, to the extracellular matrix.
• The ability of integrins to reversibly bind matrix components is dependent on their ability to change conformation between active and inactive states.