extracellular matrix Flashcards
How Much of Our Body is Cells?
50%
whats specialised ECM
-tendons- connects muscles to the bone- high tensile strength
-hair- fibrous and loose- long chords of secreted matrix
-bone- calcified, can shift but not like cells
-skin- elastic
-cornea- transparent
whats are some ECM Features
-Extracellular Meshwork Of Proteins And Hydrated Macromolecules
-Regulates:
=Migration
=Tissue Integrity And Cell Shape
=Proliferation
=Differentiation
what is the appearance of ECM
-basal lamina- a ECM more specialed version
-collagen fibre and elastic fibre- structure
-hyaluronan, proteoglycans, and glycoproteins
what are the different types of ECM
-Fibrous Proteins- Collagens, Elastin
-Adhesion Proteins- Fibronectin, Laminin
-Hydrated Macromolecules (sugars)- Glycosaminoglycans (Gags), Proteoglycans (Protein + Gags)
whats collagen
-Main ECM component
-cables of collagen
-cables look like dots when looking at it from a different angle
-20 - 40 Variants
-Glycine-proline-hydroxyproline triplet repeats
-Triple Helix
-3 alpha Chains
-Produced by fibroblasts and epithelial cells
what are some Collagen Defects
-Ehlers-danlos Syndrome: Vascular Form, Arterial Rupture
-means that skin doesnt have structural integrity
whats needed for collagen synthesis
-vitamin C
1) synthesis of pro-alpha chain
2) hydroxylation of selected prolines and lysines
3) glycosylation of selected hydroxylysines
4) self-assembly of 3 pro-alpha chains
5) pro collagen triple-helix formation
6) secretion
7) cleavage of pro peptides
8) self-assembly into fibrils
9) aggregation of collagen fibrils to form collagen fibre
how’s elastin formed
-tropoelastin-> elastin catalysed by lysyl oxidase
-50% of dry weight of aorta
-elastin fibres are cross linked to ensure maximum stress
-as you stretch elastin you gain more strength
whats fibrillin
-Elastin laid down over microfibril scaffold of fibrillin
-Marfan syndrome- fibrilin defect- more growth
-Bones, eyes
-Aortic rupture
whats GAG’s Glycosaminoglycans
-Disaccharide chains, 70-200 units long
-Highly charged- hold water in portion an allows them to interact with other things such as signals
-Proteoglycan- 95% sugar, 80 saccharides
-Glycoprotein- 60% sugar, 15 saccharides
-hold water in the body
can have different sugars
-consists of serine, GAG and link tetrasaccharide
whats Hyaluronan Complexes
-Aggrecan- sugar chains with protein core
whats Adhesion Glycoproteins: Laminin
-epithelium
-basal lamina
-defines edge of skin
-laminin needs to be interacting with lots of things
-long alpha chain with beta and gamma chain wrapped around it
-at the left end its integrin (base of cell adhesion)
-then there is nidogen
-self-assembly where the beta and gamma chain wrap around
-integrin at both ends
whats Adhesion Glycoproteins: Fibronectin
-quite a few domains
-disulfide bonds formed for cross linkage
-have binding sites for collagen
-self-association
whats Integrins
-Bind matrix through divalent cations e.g. Ca2+- regulates important reactions where this provides a chord for a strong bond to form
-Removal of cations causes cells to detach
-forms dimeric proteins
whats are some Focal Adhesion Components
-Transmembrane receptor
-Connection to cytoskeleton
-Signalling
-contains talin
Knockouts of Focal Adhesion Proteins
-β1-integrin-Embyonic lethal at implantation (Day 5) (can’t survive without them)
-α5-integrin- a5β1-integrin fibronectin receptor (more specialised), Embyonic lethal mesoderm development (Day 10)
-Fibronectin- embryonic lethal (Day 9)
-Talin- Embryonic lethal (Day 6-8)
whats are some Integrin-related defects
-αIIbβ3-integrin:
=Platelets bind fibrinogen to clot blood
=Glanzmann’s thrombasthenia
=Bleeding gums and nose bleeds
-β2-integrin
=Leukocyte Adhesion Deficiency (LAD) syndrome
=Impaired expression
=Recurrent bacterial infections
