CMB2001/L05 Transcriptional Responses to Stress & Infection I

Question 1

What 3 factors are required for adaptation to environmental challenge?

Answer 1

Sensors
Signalling pathway
Effector

Question 2

What is the common role of the NF-kB, p53 and HIF pathways?

Answer 2

Allow the cell/organism to respond to environmental threats

Question 3

Give 3 roles of the NF-kB family of transcription factors.

Answer 3

Regulating inflammation
DNA damage
Cell death
Cell adhesion
Proliferation

Question 4

What does the Rel Homology Domain of mammalian NF-kB encode?

Answer 4

DNA bin and dimerisation functions of NF-kB

Question 5

What precursor proteins are p50 and p52 proteolytically processed from?

Answer 5

p105 and p100 respectively

Question 6

What allows p100 and p105 to function as lkB-like inhibitors?

Answer 6

They contain ankyrin repeats in C-termini

Question 6

Name 2 non-conserved transcriptional activation domains in NF-kB.

Answer 6

TA1/TA2
TAD
SD1
SDII

Question 7

What form do NF-kB take to bind DNA?

Answer 7

Dimers

Question 8

What is the function of E3 Ubiquitin ligase?

Answer 8

Facilitates attachment of ubiquitin chains to target protein

Question 9

Describe the Ubiquitin-proteasome pathway of protein degradation. (6)

Answer 9

Ub conjugated to proteins for degradation by ATP-dependent process
5-Ub chain attached to substrate
Recognition by 26S proteasome
UB removed and protein linearised
Injected into proteasome core
Digested to peptides then amino acids by peptidases or used for antigen presentation

Question 10

What can induce NF-kB? (3)

Answer 10

Inflammatory cytokines
Bacterial products
Viral proteins & infection
DNA-damage
Cell stress

Question 11

Describe activation of NF-kB. (8)

Answer 11

Ligand binding
Activated IKK Kinase
IkB kinase complex
NF-kB in inactive cytoplasmic complex
IkB is phosphorylated
IkB is ubiquinated
IkB is proteolytically degraded
NF-kB translocates to nucleus

Question 12

Give the 3 core subunits of the IkB complex.

Answer 12

IKKa
IKKB
IKKy (NEMO)

Question 13

Give the 3 inhibitors of NF-kB.

Answer 13

IkBa
IkBB
Bcl-3

Question 14

How are ikB proteins similar to p105 and p100? (3)

Answer 14

Contain ankyrin repeat motifs (ANK) in C termini
PEST
Domain rich in proline, glutamate, serine and threonine

Question 15

Using NF-kB, give the sensor, signalling pathway and effector response of the body to an environmental challenge.

Answer 15

TNF receptor
IkB complex
NF-kB transcription factors

Question 16

What 2 pathways can lead to activation of NF-kB?

Answer 16

Classical/ canonical pathway
Non-canonical (alternative) pathway

Question 17

How are many NF-kB genes shared?

Answer 17

Between subunits