Cell Proliferation Regualtion

Question 1

What causes cells to synthesis and progress through the cell cycle

Answer 1

Mitogenic signalling - allows cells to pass R point (restriction point) which is located at end of g1 phase - thus allowing synthesis

Question 2

What is the rough process of regulating cell proliferation

Answer 2

Mitogen is released
Mitogen binds to receptor
Receptor is phsophorylated
Intracellular signalling results in activation of TF
TF tranlocates to nucleus
Protein specific to cell proliferation is synthesised

Question 3

What is MAPK signalling cascade

Answer 3

It is the process used downstream of receptor tyrosine kinases
It uses kinases acitivity and relays signal intracellularly

Question 4

Describe the pathway for regulating cell proliferation

Answer 4

EGFR - example of receptor tyrosine kinases
Uses MAPK signalling cascade to produce phosphoryated proteins and TF

Question 5

What mutation can occur in the ERK (extracellular regulated kinase) pathway to cause cancer

Answer 5

B raf mutation

Question 6

What is the B-RAF mutation

Answer 6

• subtype of RAF protein & relays signal to MEK
  Mutation causes RAF to receive a signal without RAS
  Thus gain in function mutation

Results in continuous signal being relayed to ERK and activation of transcription factors thus continuous expression of proteins and thus cancer

Question 7

What can be used for the treatment of b raf mutation

Answer 7

Kinase inhibitors - blocks action of BRAF - thus cells stop dividing and apoptosis of cells occurs

Question 8

How is cell proliferation stopped?

Answer 8

Question 9

What do cells use to mai tan a certain proliferation rate (stop it from becoming cancer)

Answer 9

Using P53

Question 10

What is the role of p53

Answer 10

When dna is damaged by stimuli such as UV, hypoxia, and DNA breakage it activates p53
P53 causes cell cycle arrest, apoptosis and DNA repair

Question 11

How is p53 regulated

Answer 11

-needs to be kept in low levels
- does this by being bound to MDM2 - making p53 ubiquinated
- it is then transported to proteasome for degradation
WHEN DAMAGE:
- dna damage causes phosphorylation of p53
- mdm2 can no longer bind to phosphorylated p53
- p53 accumulated leasing to apoptosis, mediating dna repairs, and cell cycle arrest