L8-9: Cell migration

Question 1

What are the five steps of cell migration

Answer 1

1. cell polarization
2. leading edge protrusion
3. leading edge adhesion
4. cell body translocation
5. trailing edge de-adhesion and retraction

Question 2

How dose Rac1, Cdc42, Rho amount depend on the leading and trailing edge of the cell? How does this effect actin polymerization and contractility?

Answer 2

More Rac and Cdc42 in the leading edge > more actin polymerization. Less Rho > less contractility

Less Rac and CDC42 in trailing edge > less poly. More rho > more contractility

Question 3

what sort of technique can be used to check Rac1 activation in cell?

Answer 3

optogenetics

Question 4

What is the lamellipodia formation pathway?

Answer 4

Rac1 > wasp family > ARP > lamellipodia

Question 5

What are the fastest cells in the world?

Answer 5

fish keratenocyte

Question 6

In the leading edge, would cofilin be abundant near the edge of the cell? Why or why not? What is the function of cofilin?

Answer 6

it would be inside the cell. Cofilin is reponsible for actin depolymerization

Question 7

Which complex helps with actin polymerization?

Answer 7

ARP complex

Question 8

What are two essential proteins in trailing edge contractility?

Answer 8

Rho and Myosin II

Question 9

Trailing edge contractility pathway?

Answer 9

Rho > Myosin II > parallel actin depoly

Question 10

What is essential for actin and ECM connection? What is the process called?

Answer 10

Integrins. Focal adhesion

Question 11

What does integrin bind to in cellular and extracellular side?

Answer 11

cellular: talin/paxilin + actin
extracellular: fibronectin

Question 12

Explain molecular clutch hypothesis and its effect on protrusion during engaged clutch.

Answer 12

integrin binds to core proteins that act as friction to slow down actin treadmilling.

• causes slower actin retrograde flow
• stronger protrusion

Question 13

Does the size of focal adhesion complex change cell migration speed? How?

Answer 13

too small > very little adhesion > slow ms
too big > too much adhesion > slow ms
only operates properly in the right size

Question 14

What downstream proteins are effected by integrin based adhesion?

Answer 14

MAPK and ERK2. normal growth factor response is also increased.

Question 15

Does the distribution of fibronectin matter in normal growth factor response? Why or why not?

Answer 15

well distributed fibronectin is needed. A single dense source of fibronectin doesnt allow cell movement and growth, resulting in cell apoptosis.

Question 16

Integrin has its own kinase domain. True or False?

Answer 16

False

Question 17

Can src normally bind to FAK? Why or why not

Answer 17

FAK has an autoinhibitory loop that doesnt allow src binding.

Question 18

What allows src to bind to FAK?

Answer 18

integrin or growth factor activation

Question 19

Two downstream effects of src-FAK complex formation

Answer 19

Rho GAP and GEF

Question 20

Where does src bind FAK?

Answer 20

Tyr397