Non-coding lncRNAs 1

Question 1

What are ncRNAs?

Answer 1

Non-coding RNAs

Not translated into protein (functional RNA = end product)

Question 2

What are the 2 main classes of ncRNAs?

Answer 2

Housekeeping

Regulatory (gene regulation)

Question 3

Name 3 housekeeping ncRNAs

Answer 3

rRNA
tRNA
snRNA

Question 4

Name 4 regulatory specific ncRNAs

Answer 4

miRNA (micro)
siRNA (small interfering)
piRNA (Piwi interacting)
lncRNA (Long non-coding)

Question 5

When was protein coding mRNA discovered?

Answer 5

1961

Question 6

When was the 1st lncRNA (H19) discovered?

Answer 6

1989

Question 7

What transcribes ncRNAs?

Answer 7

RNA polymerase II (same as protein coding RNAs)

Question 8

What length are lncRNAs?

Answer 8

> 200 nucleotides

Question 9

Do lncRNAs a polyA tail + 5’ 7-methylguanosine cap?

Answer 9

Yes

Question 10

Name the different classes of lncRNAs

Answer 10

Sense overlapping transcript
Intergenic
Intronic
Bidirectional
Antisense transcript
3' UTR associated transcript

Question 11

What are intergenic lncRNAs?

Answer 11

Don’t overlap protein coding genes
Have their own promoter
Associated w/ transcriptional control

Question 12

What are the differences bet. protein coding genes + non-protein coding lncRNA genes?

Answer 12

lncRNAs have:
= shorter transcript length
= fewer no. of exons
= less expressed
= much more tissue specific expression

Question 13

What is the advantage of lncRNAs being tissue specific?

Answer 13

Can be drug targets w/ minimal side effects

Question 14

lncRNAs have functions in development + differentiation.

Name 2 examples

Answer 14

Xist = silencing of 1 X chromosome

line-MD1 = muscle differentiation

Question 15

What is the most common type of variation of DNA bet. cancer patients + controls?

Answer 15

Single-nucleotide polymorphisms (SNPs)

Question 16

How were SNPs in DNA associated with cancer?

Answer 16

GWAS (Genome-wide association studies)

Question 17

Where are the majority of cancer associated SNPs found?

Answer 17

Within lncRNA loci

Question 18

What types of DNA changes are associated w/ cancer?

Answer 18

Single-nucleotide polymorphisms (SNPs)
Somatic copy-number alterations (SCNAs)
Amplification + deletion of lncRNAs

Question 19

What are focal SCNAs?

Answer 19

Somatic copy-number alterations that cover 1 or 2 genes

Question 20

Amplified or deleted lncRNAs are mostly found where?

Answer 20

Short focal alteration regions that contain no known cancer-associated protein-coding genes
-> may play a role in cancer

Question 21

Different cancers show different patterns in lncRNA expression

Answer 21

lncRNAs = expressed in tumour specific manner

lncRNA expression signatures can be used to distinguish cancer cells from normal cells

Question 22

What % of cancer associated SNPs are located in the non-coding portion of the genome?

Answer 22

> 80%

Question 23

LncRNAs expression in cancers: which one of these statements is wrong?

(A) A large number of lncRNAs are expressed in most cancers
(B) Cancers show specific patterns of lncRNA expression
(C) lncRNAs show similar patterns of expression in cancerous and normal tissue

Answer 23

C

Question 24

What is HOTAIR lncRNA?

Answer 24

Acts as an oncogene
Promotes breast cancer metastasis
Powerful prognostic marker (high expression -> lower survival)

Question 25

What is H19 lncRNA?

Answer 25

Acts as tumour suppressor
Normal function = gene imprinting
Maternally expressed
Inactivation in cancer by promoter hypermethylation