Download Animal cell culture lecture -3

Animal cell culture
lecture -3Cell – matrix interaction
By: Saib H. Al Owini
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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- Glycosaminoglycans
GAGs
• 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
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
-Stiff
-Long
-Triplehelix
-With prolin and glycin
-27 types the famous
-Type 1 in CT.
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
1-Fibronectin
• Large glycoprotein
• Dimer of tow lager subunits linked by disulfide
bond.
2- Laminin,
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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.
laminins
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.