regulation of transcription factor II

Question 1

what is tumor hypoxia?

Answer 1

low oxygen tension <1% O2
- increases with increasing distance from capillaries
- activates genes involved in angiogenesis, tumor cell migration and metastasis

Question 2

what is involved in hypoxia to form new blood vessels?

Answer 2

• VEGF
• PDGF-b
• FGF-3
• endotheline 1 & 2
• angiopoietin-2
• VEGF receptor (FLT-1)
• Nitric oxide synthase 2 (NO)
• heme oxygenase 1 (CO)

Question 3

what is involved in hypoxia to form red blood cells?

Answer 3

erythropoetin

Question 4

what is involved in hypoxia for anaerobic glycolysis?

Answer 4

• GLUT 1,3
• hexokinase 1,2
• phosphofructukinase L, C
• aldolase A,C
• triosephosphate isomerase
• GAPDH
• phosphoglycerokinase 1
• enolase 1
• pyruvate kinase M
• lactate dehydrogenase A
• carbonic anhydrases 9,12

Question 5

what is HIF?

Answer 5

hypoxia inducing factor

Question 6

what is HIF involved in?

Answer 6

• hormonal regulation
• cytoskeleton formation
• cell proliferation
• vasomotor regulation
• growth and apoptosis
• energy metabolism
• angiogenic signalling
• matrix and barrier functions
• transcriptional regulation
• transport
• virus related

Question 7

HIF mediates hypoxic response

Answer 7

• TF that regultes hypoxia induced gene transcription
• heterdimer HIF-1a and 1b subunits
• HIF-2a
• HIF-1/2a levels are tightly regulated by O2 and degraded in normoxia but stabilised in hypoxia

Question 8

HIF subunits

Answer 8

bHLH; basic helix loop helix
PAS; per-arnt-sim
TAD; transactivation domain C-terminus or N terminus
ODD; oxygen dependent degradation domain

Question 9

normoxia

Answer 9

• 3 proline hydroxylase enzymes (PHDs) in presence of O2 and cofactors hydroxylate HIF
• recognition by von Hippel Lindau (VHL) protein; an E3 ligase which targets HIF for degradation via ubiquitination

Question 10

hypoxia process

Answer 10

• PHDs inactive, HIF translocates to nucleus
• activates genes involved in angiogenesis, tumor cell migration and metastasis

Question 11

what are some growth factor mediated pathways?

Answer 11

• insulin
• IGF-1 increase HIF protein synthesis in normoxia
• RTK signalling increased

Question 12

mTOR

Answer 12

mammalian target of rapamycin

Question 13

PI3K

Answer 13

phosphoinositide 3 kinase

Question 14

AKT

Answer 14

protein kinase B

Question 15

kinase/MAPK

Answer 15

mitogen activated protein kinase

Question 16

kidney cancer/ RCC

Answer 16

• highly angiogenic tumor

Question 17

what happens to VHL in RCC?

Answer 17

tumor suppresion protein von Hippel-Lindau (VHL) is mutated in >80% of clear cell RCC
- loss of VHL function leads to expression of TFs hypoxia inducible factor-1 and 2
- HIF-2a is the oncogenic driver

Question 18

p53 function and regulation

Answer 18

• most frequently altered gene in human cancers
• in normal unstressed cells p53 protein is low
• regulated by MDM2/HDM2 by binding to the N-terminal transactivation domain
• promoting p53 ubiquitination and degradation by E3 ligase activity

Question 19

list of p53 functions

Answer 19

• hypoxia
• DNA damage
• ribosomal stress
• oncogene activation
• senescence
• genomic stability
• DNA repair
• survival
• cell cycle arrest
• apoptosis
• nutrient deprivation
• telomere erosion

Question 20

what can p53 help promote?

Answer 20

repair and survival of damaged cells, or it can promote the permanent removal of damaged cells through death or senescence

Question 21

p53 structure

Answer 21

TD: transactivator domain required for transcriptional activation
PD: poly-proline domain, required for protein-protein interaction
NLS: nuclear localisation signal
OD: oligomerisation domain
R: regulator domain

Question 22

p53 after DNA damage

Answer 22

increase in p53 levels with increased ability of p53 to bind DNA and mediated transcriptional activation

Question 23

summary of HIF

Answer 23

HIF activates VEGF pathway and subsequent further downstream cell signalling via RTK