Tumour Suppresor Genes

Question 1

What are some characteristics of tumour suppressor genes?

Answer 1

Loss of function, mutation event is 2, often recessive, can be somatic or Germline. Negatively regulate growth promoting genes. Mutation is deletion or point mutation

Question 2

How does tumour suppressor loss cause cancer?

Answer 2

Selective growth of these cells and it’s colonies

Question 3

What are some examples of tumour suppressor genes?

Answer 3

P120(GAP)

Pten

Question 4

How did they come to know what tumour suppressor genes are?

Answer 4

Somatic cell hybridization and familial studies

Cytogenetic studies through karyotypic analysis

Question 5

Somatic mutational event causing the second tumor suppressor gene to be lost is common

Answer 5

False

Question 6

What are the main important functions of tumour suppressor genes?

Answer 6

They regulate proliferation and they maintain genome stability

Question 7

How can tumour suppressor be lost chromosome wise?

Answer 7

Chromosomal nondisjunction
Chromosomal non disjunction with duplication
Gene conversion
Mitotic recombination

Question 8

How is loss of heterozygosity detected?

Answer 8

Restriction fragment length polymorphism

Question 9

Is loss of heterozygosity a must for neoplasia?

Answer 9

No

Question 10

How can haploinsufficiency happen?

Answer 10

It can directly block the wild type gene
The TS can become mutated through other epigenetic mechanism
The haploid allele May not be enough to regulate downstream signalling

Question 11

What chromosome is retinoblastoma on?

Answer 11

Chromosome 13

Question 12

What does RB bind to?what part of Rob is highly mutated?

Answer 12

E2F promoter

A/b pocket

Question 13

What is rb function? How does it work?

Answer 13

Tumour suppressor that regulates cell cycle, the restriction point, progression of cell cycle from g1 to a s phase. At the g1 phase it’s underphosphorylated and it’s bound to e2f once it approaches the late g1 phase it gets hyperphosphorylated and it releases from e2f site and transcription of s phase genes and it gets dephosphorylated in anaphase

Question 14

Which viruses inactivate rb? What oncoprotein?

Answer 14

Hpv-E7
Sv40 virus t antigen
Adenovirus e1a protein

Question 15

What cellular processes does rb regulate?

Answer 15

Apoptosis
DNA replication
DNA repair

Question 16

What is the promoter specific regulation model and context dependent regulation model propose? Which one is correct?

Answer 16

Promoter specific regulation- rb phosphorylated by cal when I’m the promoter of s phase gene but if On apoptosis promoter will be degraded by Caspase
Context dependent regulation- either degradation is effective, when going to replicate the apoptosis genes won’t need to be activated.
Both

Question 17

Which chromosome is p53 on?which exon? 1/2 life?

Answer 17

Chromosome 17,11

6-20 min

Question 18

What cellular functions does p53 mediate? Give example of the target genes of each function

Answer 18

Cell cycle arrest-p21
, DNA repair-PCNA and XPX, apoptosis-bax, puma
, block of angiogenesis, differentiation-thrombospondin

Question 19

P53 acts as a tetramer

Answer 19

True

Question 20

What viruses inactivate p53

Answer 20

Sv40 large t, hpv e6, adenovirus e1b

Question 21

How is p53 degraded? What prevents the degradation?

Answer 21

Mdm2 binds to it and targets it for ubiquitination and it’ll be exported out of the nucleus.
Arf bunds to mdm2 and sequesters it in the nucleoli preventing export which is needed for degradation. the phosphorylation of p53 also prevent mdm2 from interacting with it

Question 22

What upregulates p53?

Answer 22

ATM kinases and ATR kinases releases it from mdm2

Question 23

What are p73 and p63 involved in?

Answer 23

Development

Question 24

What is BRCa2 important?

Answer 24

DNA repair