Therapeutic potential of regulatory RNAs 1 2.0

Question 1

What can siRNAs do to a mutated genes mRNA?

Answer 1

“knock-down” the mRNA

Question 2

Which body cells possess the machinery which constitutes a functional siRNA/miRNA pathway?

Answer 2

All body cells

Question 3

What takes up siRNAs?

Answer 3

RISC complex (RNA Induced Silencing Complex)

Question 4

What does the RISC complex use siRNA for?

Answer 4

A scanning target for mRNA

Question 5

What happens to mRNA with sequence complementarity to siRNA?

Answer 5

It is bound by the siRNA

Question 6

What happens to mRNA once bound to siRNA?

Answer 6

It is degraded by enzymatic components of the RISC complex

Question 7

What kind of organisms use siRNA/RISC to combat viral infection?

Answer 7

Plants and other lower organisms

Question 8

What do plants and other lower organisms use RISC for?

Answer 8

A means of combating viral infection

Question 9

How is siRNA manipulated by scientists?

Answer 9

an siRNA that has sequence complementarity to any mRNA of interest is designed and this can be used to knock down mRNA

Question 10

What is an example of a type of gene that siRNA can be used to target?

Answer 10

Oncogenes

Question 11

What is the philadelphia chromosome?

Answer 11

A fusion of chromosome 9 and 21

Question 12

What is the issue with the philadelphia chromosome?

Answer 12

Where the chromosomes fuse creates a BCR-ABL oncogene which is cancerous

Question 13

What is caused by the BCR-ABL oncogene?

Answer 13

Leukaemia

Question 14

How can siRNA help therapeutically with leukaemia?

Answer 14

siRNA against fusion point between BCR and ABL gene is designed,

Question 15

Why is the siRNA against leukaemia on the philadelphia chromosome targeted specifically against the fusion point of the BCR and ABL gene?

Answer 15

So it doesn’t target any normal BCR or ABL genes that aren’t fused

Question 16

Where is the BCR gene found?

Answer 16

Chromosome 22

Question 17

Where is the ABL gene found?

Answer 17

Chromosome 9

Question 18

Why is siRNA a useful way of targeting viral infections?

Answer 18

siRNA can be quickly redesigned to keep up with mutations of the virus

Question 19

Why can siRNAs not be given orally?

Answer 19

The acid contents in the stomach degrades siRNAs

Question 20

How must siRNAs be adminitered?

Answer 20

Intravenously

Question 21

What is an issue with administering siRNAs intravenously?

Answer 21

There are exonucleases in the blood that will recognise the siRNAs as foreign and start to degrade them, as well as immune cells that do the same thing

Question 22

Issue with siRNA size?

Answer 22

They are rapidly filtered by the kidneys and so cleared

Question 23

Issue with siRNAs and plasma membrane?

Answer 23

They have an overall -ve charge (RNA phosphate backbone) so they can not cross cell membranes

Question 24

How is the immune response to siRNAs combated?

Answer 24

You can change the RNA structure that repels the immune system and exonucleases

Question 25

What edits are done to siRNA to prevent exonucleases and the immune system from attacking?

Answer 25

Add a 2' O-methyl group instead of a hydroxyl group, phosphorothionate linkages

Question 26

In what direction do most exonucleases act?

Answer 26

5' to 3'

Question 27

How does adding a 2' O-methyl group to siRNA prevent exonuclease degradation?

Answer 27

Recognition from the exonuclease is prevented

Question 28

What do phosphorothioate linkages replace?

Answer 28

Phosphodiester bonds

Question 29

Difference between phosphodiester bonds and phosphorothioate bond?

Answer 29

Oxygen atom is changed to a sulfur