Extracellular Matrix Flashcards
What is the extracellular matrix?
A mesh of proteins and hydrated molecules
What are the functions of the ECM?
- Establish cell integrity and shape
- Proliferation
- Differentiation
- Migration
- Microbe defence
What are the components of the ECM?
- Fibrous proteins
- Adhesion proteins/Glycoprotein
- Hydrated macromolecules
Give examples of fibrous proteins present in the ECM
e.g. collagens, elastin
Give some examples of adhesion proteins/glycoproteins present in the ECM
e.g. fibronectin, laminin (component of basal lamina)
What does the basal lamina do?
Helps cells know their positioning
Give some examples of hydrated macromolecules in the ECM
e.g. glycosaminoglycans (GAGs), proteoglycans (protein + GAGs)
What is the main ECM component?
Collagen
What is the structure of collagen?
Triple helix - 3 α chains
How does one know the importance of collagen?
Based on how many diseases are associated with collagen defects
Give an example of a collagen defect and its effect
Ehlers-Danlos syndrome
Defect with collagen assembly so loose joints –>susceptible to osteoarthritis
What does the vascular form of Ehlers-Danlos syndrome entail?
Arteries that are prone to rupture
Where is collagen modified extensively during its synthesis?
In the Golgi body
What does hydroxytransferase require in the synthesis of collagen?
Vitamin C
Which enzyme is used during the synthesis of collagen?
Hydroxytransferase
Selected strands are ________ during collagen synthesis
Glycosylated
Which protein forms connective tissue?
Elastin
Reaction to form elastin
Tropoelastin —-> elastin
requires lysyl oxidase
Which enzyme is catalyses the polymerisation of tropoelastin to elastin?
Lysyl oxidase
Elastin is combined with which protein to form fibres?
Fibrillin
Give an example of a genetic disorder to do with connective tissue
Marfan’s syndrome
Which gene is mutated in Marfan’s syndrome?
FBN1
Symptoms of Marfan’s syndrome
- Elongated limbs
- Problems with eyelids
- Cardiac problems
How is the matrix kept hydrated?
Sugars (e.g. GAGs, disaccharide chains) retain water to keep the matrix hydrated due to negative charge thus attracting Na+
Which acid attracts water and induces swelling in a wound response?
Hyaluronic acid
What are the roles of proteoglycans?
- Cushioning
- Filtering
- Signal binding
- Packing
What do proteoglycans use to break up ECM to allow migrating cells through?
Hyaluronidase
What can be used as a short term treatment for cartilage joints?
Injecting hyaluronic acid (cushioning)
What are the adhesion glycoproteins and what do they do?
Fibronectin - binds cells and collagen
Laminin - axon promoting
Where is laminin found?
In the basal lamina
What are integrins? What do they link?
ECM receptors
Link the ECM and cytoskeleton
Give an example of a disease associated with a defect in integrins
Glanzmann’s thrombosthenia
What happens if you have Glanzmann’s thrombosthenia?
Problem with platelets, don’t bind to fibrinogen –> blood doesn’t clot
How are integrins, ECM and cytoskeletal proteins involved in regulating cell movement?
Form focal adhesions
Does integrin bind to actin?
Not directly
What type of collagen is the most common? Where is it most commonly found?
Type I. In skin and bones
