Cytoskeleton: Intermediate Filaments

Question 1

What kind of cells need a lot of intermediate filaments?

Answer 1

Cells that are subject to a lot of stress and distortion

Question 2

What is one of the protein subunits of IFs?

Answer 2

keratin

Question 3

What are the 3 main functions of IFs?

Answer 3

Cell shape
anchoring nucleus & other organelles
forming nuclear lamina

Question 4

What is the structure of IFs?

Answer 4

8 tetramers twisted together to form a rope like structure

Question 5

IF is made of 8 ___

Answer 5

tetramers

Question 6

A tetramer has no ____

Answer 6

polarity

Question 7

Is ATP or GTP needed for IF subunit assembly?

Answer 7

Neither - it is thought phosphorylation controls it

Question 8

What is the name of IF in nucleus?

Answer 8

nuclear lamins

Question 9

Where do cytoplasmic IFs anchor?

Answer 9

cell-cell junctions, specifically in hemidesmosomes & desmosomes

Question 10

What kind of cell are nuclear IFs expressed?

Answer 10

Any cell with a nucleus!

Question 11

What kind of cell are vimentin-like IFs expressed?

Answer 11

mesenchymal origin (fibroblasts, endothelial cells)
muscle
glial cells
neurons

Question 12

What kind of cell are epithelial IFs expressed?

Answer 12

epithelial cells & derivatives ie. hair and nails

Question 13

What kind of cell are axonal IFs expressed?

Answer 13

neurons

Question 14

How are IFs helpful in identifying where cancer originited?

Answer 14

Can tag with fluorescent antibodies - can see if cancer originated in epithelial, mesenchymal, or neuronal tissue based in IFs present

Question 15

What is the result of defective keratin IFs?

Answer 15

tissues will rupture

Question 16

In each layer of skin, there are different kinds of what?

Answer 16

IFs

Question 17

What happens if there is a defect in basal layer of keratin IFs in skin?

Answer 17

Any kind of friction or pressure will cause skin to peel. The epidermis will peel away from the dermis

Question 18

Key words: keratin 5 or 14, areas of mechanical friction, blisters ABOVE basal lamina are what disease?

Answer 18

Epidermolysis Bullosa Simplex (EBS)

Question 19

Characteristics: Fragile skin: minor mechanical friction/trauma → recurrent blister formation are what disease?

Answer 19

Epidermolysis Bullosa Simplex (EBS)

Question 20

What is the mechanism for EBS?

Answer 20

Rupture of keratin IFs in the epidermal basal layer connecting to basal lamina

Question 21

What does EBS stand for?

Answer 21

Epidermolysis Bullosa Simplex

Question 22

What is the mode of inheritance for EBS?

Answer 22

AD

Question 23

Where is the defect for EBS?

Answer 23

Intermediate filaments - Keratin 5, 14 – basal layer (above basal lamina)

Question 24

What keratin are defected in EBS?

Answer 24

5, 14

Question 25

Key words: keratin 1 or 10, easy blistering, chronic wounding, hyperproliferation are what disease?

Answer 25

Epidermolytic Hyperkeratosis (EH)

Question 26

EH stands for what?

Answer 26

Epidermolytic Hyperkeratosis (EH)

Question 27

Characteristics: Red skin and blisters at birth are what disease?

Answer 27

Epidermolytic Hyperkeratosis

Question 28

Where is defect in epidermolytic Hyperkeratosis?

Answer 28

Intermediate filaments - Keratin 1, 10 – suprabasal layer (spinous & granular layer of epidermis)

Question 29

What keratin are defected in EH?

Answer 29

1, 10

Question 30

What is the mechanism for EH?

Answer 30

Defect weakens structural stability of keratinocytes → easy blistering; chronic wounding → hyperproliferation and thickened scaly skin

Question 31

key words: keratin 9, palms and soles of feet only is what disease?

Answer 31

Epidermolytic Plantopalmar Keratoderm (EPPK)

Question 32

What does EPPK stand for?

Answer 32

Epidermolytic Plantopalmar Keratoderm (EPPK)

Question 33

Characteristics: Restricted to epidermis of palms and soles (only place keratin 9 is found) are what disease?

Answer 33

EPPK

Question 34

What keratin is defected in EPPK?

Answer 34

9

Question 35

What is the name of the muscle IF that helps line up myofibrils?

Answer 35

Desmin

Question 36

Where is the IF GFAP expressed?

Answer 36

Glial cells