Extracellular Matrix

Question 1

What is the extracellular matrix?

Answer 1

A mesh of proteins and hydrated molecules

Question 2

What are the functions of the ECM?

Answer 2

• Establish cell integrity and shape
• Proliferation
• Differentiation
• Migration
• Microbe defence

Question 3

What are the components of the ECM?

Answer 3

• Fibrous proteins
• Adhesion proteins/Glycoprotein
• Hydrated macromolecules

Question 4

Give examples of fibrous proteins present in the ECM

Answer 4

e.g. collagens, elastin

Question 5

Give some examples of adhesion proteins/glycoproteins present in the ECM

Answer 5

e.g. fibronectin, laminin (component of basal lamina)

Question 6

What does the basal lamina do?

Answer 6

Helps cells know their positioning

Question 7

Give some examples of hydrated macromolecules in the ECM

Answer 7

e.g. glycosaminoglycans (GAGs), proteoglycans (protein + GAGs)

Question 8

What is the main ECM component?

Answer 8

Collagen

Question 9

What is the structure of collagen?

Answer 9

Triple helix - 3 α chains

Question 10

How does one know the importance of collagen?

Answer 10

Based on how many diseases are associated with collagen defects

Question 11

Give an example of a collagen defect and its effect

Answer 11

Ehlers-Danlos syndrome

Defect with collagen assembly so loose joints –>susceptible to osteoarthritis

Question 12

What does the vascular form of Ehlers-Danlos syndrome entail?

Answer 12

Arteries that are prone to rupture

Question 13

Where is collagen modified extensively during its synthesis?

Answer 13

In the Golgi body

Question 14

What does hydroxytransferase require in the synthesis of collagen?

Answer 14

Vitamin C

Question 15

Which enzyme is used during the synthesis of collagen?

Answer 15

Hydroxytransferase

Question 16

Selected strands are ________ during collagen synthesis

Answer 16

Glycosylated

Question 17

Which protein forms connective tissue?

Answer 17

Elastin

Question 18

Reaction to form elastin

Answer 18

Tropoelastin —-> elastin

requires lysyl oxidase

Question 19

Which enzyme is catalyses the polymerisation of tropoelastin to elastin?

Answer 19

Lysyl oxidase

Question 20

Elastin is combined with which protein to form fibres?

Answer 20

Fibrillin

Question 21

Give an example of a genetic disorder to do with connective tissue

Answer 21

Marfan’s syndrome

Question 22

Which gene is mutated in Marfan’s syndrome?

Answer 22

FBN1

Question 23

Symptoms of Marfan’s syndrome

Answer 23

• Elongated limbs
• Problems with eyelids
• Cardiac problems

Question 24

How is the matrix kept hydrated?

Answer 24

Sugars (e.g. GAGs, disaccharide chains) retain water to keep the matrix hydrated due to negative charge thus attracting Na+

Question 25

Which acid attracts water and induces swelling in a wound response?

Answer 25

Hyaluronic acid

Question 26

What are the roles of proteoglycans?

Answer 26

- Cushioning - Filtering - Signal binding - Packing

Question 27

What do proteoglycans use to break up ECM to allow migrating cells through?

Answer 27

Hyaluronidase

Question 28

What can be used as a short term treatment for cartilage joints?

Answer 28

Injecting hyaluronic acid (cushioning)

Question 29

What are the adhesion glycoproteins and what do they do?

Answer 29

Fibronectin - binds cells and collagen | Laminin - axon promoting

Question 30

Where is laminin found?

Answer 30

In the basal lamina

Question 31

What are integrins? What do they link?

Answer 31

ECM receptors | Link the ECM and cytoskeleton

Question 32

Give an example of a disease associated with a defect in integrins

Answer 32

Glanzmann's thrombosthenia

Question 33

What happens if you have Glanzmann's thrombosthenia?

Answer 33

Problem with platelets, don't bind to fibrinogen --> blood doesn't clot

Question 34

How are integrins, ECM and cytoskeletal proteins involved in regulating cell movement?

Answer 34

Form focal adhesions

Question 35

Does integrin bind to actin?

Answer 35

Not directly

Question 36

What type of collagen is the most common? Where is it most commonly found?

Answer 36

Type I. In skin and bones