ECM and adhesion Flashcards
what is a complex network of secreted macromolecules
ECM
what does GAG stand for
glucosaminoglycans
the ECM provides a 3D framework for
organisation of tissues and basic cellular processes
the ECM regulates things
proliferation, differentiation, migration, cell-cell interaction
composition of ECM macromolecular network
collagens, elastin, glycoproteins, proteoglycans
example of ECM disease- too much ECM
fibrosis
how much of total protein in body is collagen
25%
what are the primary structural components in connective tissue
collagens
how many different types of collagens have been identified
> 25
what is the structure of collagen and amino acid sequence
triple helical structure Gly-X-Y ie. every 3rd amino acid is glycine
2 main categories of collagen
fibrillar (fibril forming, well organised banded fibrils) and non-fibrillary (form microfibrils/ mesh like structures)
type I and II are what type of collagen
fibrillar
type IV and VI are what type of collagen
non-fibrillary
types I and II are major components in ? and provide ?
tendons, ligaments, skin- provide high tensile strength
type IV and VI are structural components of ? and provide ?
basement membranes- provide anchorage of cells and filtration
what is the name for brittle bone disorder
osteogenesis imperfecta
osteogenesis is caused by genetic defects in which type of collagen
collagen I
what are 5 symptoms of OI
fragile bones, think skin, abnormal teeth, think sclera, weak tendons
what amino acid is mutated in OI
glycine to a more bulky one
OI is what type of mutation
single base
which type of OI is most common I or II
type I (50%)
Type I OI is autosomal dominant/ recessive
dominant
which type of OI is the mildest
Type I
which genes are mutated in OI type I
COL1A1 and A2 genes on chromosomes 7 and 17
which type of OI is more severe
type II
what type of mutation is type II usually and is it dominant/reccessive
de novo, dominant
why do type II OI babies not often survive
bones so fragile
what is the predominant protein in elastic fibres
elastin
elastin gives flexibility to what 4 things
blood vessels, lungs, ligaments, skin
can elastin stretch in 2D or 3D
2D (1000x more stretchy than collagen)
what 2 amino acids is elastin rich in
glycine and proline (like collagen)
what amino acid makes elastin different to collagen and why
valine interacts with hydrophobic domains which gives it elasticity
elastin fibres are covered by what and why
glycoprotein fibrillin- so stretchy so needs control/ stretch without breaking
what syndrome is from mutations in fibrillin gene
marfan syndrome eg. Abraham lincoln
what are some characteristics of Marfan syndrome
tall stature, long arms and legs, spider fingers (arachnodactyl), loose joints, floppy cardiac valves, eye problems, aortic aneurysms
what helps to anchor elastin fibres to other ECM proteins
fibrillin- structural role
fibrillin controls amount of what growth factor
TGF-b
in marfan syndrome TGF-b is not bound with ECM which causes what
accumulation in lungs, heart and other tissues which changes ECM in these organs especially where there is a lot of elastic fibres
what are the 2 sugar containing proteins in animal cells
glycoproteins and proteoglycans
what is a glycoprotein
polypeptide chain with oliogosaccharide/ carbohydrate stuck on end
glycoproteins play a role in what immunity and why
innate immunity- receptors on cell surface of bacteria, viruses, toxins
2 examples of glycoproteins
laminin, fibronectin
3 roles of laminin
cell adhesion, cell migration, cytoskeletal organisation (connects epithelial cells to connective tissue)
5 roles of fibronectin
cell: adhesion, migration, shape, differentiation, cytockeltal organisation
what is composed of a peptide chain with covalently bound sugars (proteins conjugated to polysaccharides with serial repeat units)
proteoglycan
do glycoproteins or proteoglycans have more carbohydrates
proteoglycans
what is the carb and protein % in proteoglycans
95%, 5%
proteoglycans: core protein and what?
GAGs (mucopolysaccharide)
proteoglycan side chains (GAGs) contain ? group with ? charge
sulphate, -ve
are proteoglycans water attracting
yes
proteoglycans are ? forming
gel
proteoglycans can form large ? in most tissues
aggregates
proteoglycan aggregates give what to tissues
compressive strength
proteoglycans in tissues increase/ decrease with age
decrease
what happens to proteoglycans with age
shorter and fewer side chains, draw and hold less water, more likely to be damaged (dry and brittle)
proteoglycans are important in aging and ?
healing
how are proteoglycans important in healing
upregulated in damaged area, cause initial swelling (oedema), more nutrients and GF
cell adhesion :
process by which cells interact and attach to neighbouring cells using cell surface molecules
direct contact cell adhesion is between
cell surfaces
indirect interactions cells attach to
surrounding ECM
cell adhesion is involved in 3 things
signal transduction for cells to detect and respond to changes in surroundings, regulate cell migration, regulate tissue development in multicellular organisms
cell adhesion molecules CAMs belong to 5 protein families
cadherins, Ig superfamily, mucins, selectins, integrins
CAMs have homophilic (2 ) and heterophilic interactions (3)
cadherins, Ig super family
mucins, selectins, integrins
