ECM 1

Question 1

ECM Definition

Answer 1

A complex network of proteins and carborhydrates filling spaces between cells. This has both fibrillar and non-firbrillar components

Question 2

ECM Functions

Answer 2

• physical support
• determines the mechanical and physicochemical properties of the tissue
• influences the growth, adhesion and differentiation status of the cells it interacts with
• essential for development

Question 3

Connective Tissue Components

Answer 3

• Collagens e.g. Type 1,2,3 (fibrillar) and type 4 (basement membrane)
• Multi-adhesive glycoproteins e.g. fibronectin, fibrinogen and laminins (basement membrane)
• Proetoglycans e.g. aggrecan, versican, decorin and Perlecan (basement membranes)

Question 4

Osteogenesis Imperfecta Cause

Answer 4

Type 1 Collagen Gene Mutation

Question 5

Marfans SYndrome Cause

Answer 5

Fibrillin 1 Gene Mutation

Question 6

Alports Sybdrome Cause

Answer 6

Type 4 Collegen (alpha 5) Gene Mutation`

Question 7

Epidermolysis Bullosa Cause

Answer 7

Laminin 5 Gene Mutation (in all 3 chains)

Question 8

Congenital Muscular Dystrohpy Cause

Answer 8

Laminin 2 (alpha 2 ) Gene Mutation

Question 9

Hurlers Syndrome Cause

Answer 9

L-alpha-iduronidase Gene Mutation affecting ECM catabolism

Question 10

Excessive loss of ECM?

Answer 10

Osteoarthritis

Question 11

Excessive deposition of ECM?

Answer 11

• cirrhosis
• kidney fibrosis
• lung fibrosis

Question 12

Basement Membrane Componensts

Answer 12

• collagen 4
• laminins
• perlecans

Question 13

Number of collagen genes

Answer 13

42 genes

Question 14

Collagen composition

Answer 14

3 alpha chains forming a triple helix

Type 1 = (a1(I))(a1(I))(a2(I))

Type 2 = (a1(II)) x3

Type 3 = (a1(III)) x 3

Question 15

Glycine in Collagen position

Answer 15

every 3rd position

Question 16

Collagen Biosynthesis

Answer 16

Pro-collagen (N and C propetides removed once oustide the cell) —> Collagen —> fibril —-> cross-linking —-> fibre

Question 17

Hydroxyl Group Function

Answer 17

Normally formed on lysine and proline. They contribute to the Hydrogen bond formation. Lysine + hydroxy are modified in covalent cross-link formation.

Question 18

What do hydroxylases require to function?

Answer 18

Vitamin C and Iron (Fe2+)

Question 19

Fibril-Associated Collagen Names and Function

Answer 19

Type IX and XII and these associate with fibrillar collagens and regulate the organisation and size of collagen fibrils.

Question 20

Elastic Fibres Function

Answer 20

• elasticity of tissues

- elasticitiy of skin, blood vesselsand lungs.

Question 21

Elastic Fibres Structure

Answer 21

= Elastin Core + Microfibrils.

Microfibrils are rich in protein Fibrillin

Question 22

Elastin Structure

Answer 22

• Two segments: Hydrophobic regions and alpha-helical regions (rich in alanine/lysine)
• many lysine side chains are covalently cross-linked.

Question 23

Basement membrane function

Answer 23

They surround muscle, peripheral nerves and fat cells as well as underlying most epithelia. Used for the seperation of cells from the underlying connective tissue

Question 24

Basement Membrane Example

Answer 24

e.g. Glomerulus - basement membrane prevents macromoleculs from the blood into the nephron. This can result in diabetic nephropathy with ECM accumulation.