L23 Extracellular Matrix Flashcards
How much of our body is cells?
50%
Name some specialised ECM and their features
- Bone - Calcified
- Hair - Fibrous and loose
- Tendons - Tensile strength
- Skin - Elastic.
- Cornea - Transparent.
What do ECM regulate?
- They have an extracellular meshwork of proteins and hydrated macromolecules.
- They regulate migration, tissue integrity, cell shape, proliferation and differentiation.
What are the types of ECM proteins and give examples?
- Fibrous proteins - Collagen and elastin
- Adhesion proteins - Fibronectin and laminin
- Hydrated macromolecules - Glycosaminoglycan (Gags) and proteoglycans ( protein + Gags).
What is the main ECM component?
Collagen.
Describe the structure of Collagen
- They have 20 to 40 variants of collagen
- A triplet of Glycine-proline-hydroxyproline is repeated and form a long chain.
- They have a triple helix (3 polypeptide chains wind around each other)
- They have three alpha chains.
Where is collagen produced from in the body?
Fibroblasts and epithelial cells.
Give one collagen defect and what it causes
- Ehlers-danlos Syndrome (affects body’s connective tissues) - vascular form and arterial rupture.
Why does collagen needs to be synthesised? (Check)
Collagen undergoes hydroxylation to need to form a strong structure instead of it being comprimised.
What happens when elastin is stretched?
When elastin is stretched, it becomes deformed because its flexibility and recoil is essential for organs such as lungs and skin
How much percentage of elastin is in Aorta?
50% dry weight
What is elastin formed from? (Check)
Elastin is synthesised from Tropoelastin using Lysyl oxidase.
What is Fibrillin?
Fibrillin is a glycoprotein that plays a crucial role in the formation and structure of connective tissues throughout the body.
What does elastin laid down over microfibril scaffold of fibrillin cause? (Check)
Marfan syndrome which extends bones, eyes and causes aortic rupture.
What are GAG’s Glycosaminoglycans?
- They are Disaccharide Chains.
- 70-200 units long
- Highly Charged (polar)
Give some examples of GAG’s Glycosaminoglycans?
- Proteoglycan - 80 saccharides. 95% sugar.
- Glycoprotein - 15 Saccharides. 60% sugar.
What are Hyaluronan complexes?
Hyaluronan complexes are mixtures of different molecular weight forms of hyaluronic acid. Hyaluronic acid (HA) is a naturally occurring substance found in the body, particularly in the skin, joints, and eyes.
Aggrecan
What are the roles of Hyaluronan complexes?
It plays a crucial role in hydration, tissue repair, and lubrication
Name a few adhesion glycoproteins
Laminin, Fibronectin
What are integrin in Laminin?
Integrins is the part of the laminin which is responsible for adhesion.
What are Fibronectin?
Fibronectin contains specific domains that bind to integrity receptors on cell surfaces. This interaction promotes cell adhesion and anchors cells to the ECM
What are the features of integrin?
- Bind matrix through divalent cations (+2 charge)
- Removal of cations causes cells to detach.
- They from dimeric proteins.
- They have a transmembrane for signalling.
What is the role of focal adhesions?
- Transmembrane receptors recieve signals.
- Connection of cytoskeleton.
- Signalling
What are the knockouts of focal adhesion proteins?
- b1-integrin
- a5-integrin
- Fibronectin
- Talin
What does focal adhesion knockouts cause?
Embryonic lethality.
Name some integrin related defects (do more)
- αIIbβ3-integrin defect.
- β2-integrin
What are the symptoms of αIIbβ3-integrin defect?
- Platelets bind fibrinogen to clot blood
- Glanzmann’s thrombasthenia
- Bleeding gums and nose bleeds
What are the effects of b2 integrin?
- Leukocyte Adhesion Deficiency (LAD) syndrome
- Impaired expression
- Recurrent bacterial infections
