RNA interference II

What does dicer do besides recognize dsRNA, bind to it, and cut it?

It recognizes a protein called argonaute that will bind to dicer.

What does argonaute do?

It binds to dicer and recognizes the siRNAs and takes these pieces to the RISC complex.

What is the RISC complex made of?

1. RNA

2. RNA binding proteins

3. Argonaute

What does the RISC complex do?

It uses one of the siRNAs to find complementary strands of mRNA to hybridize and cut them.

What does argonaute 2 cleave? Why?

The sense strand of RNA so the siRNA-RISC complex can bind and degrade complementary mRNA

Can the siRNA in the RISC complex degrade itself?

No it does not

Can the siRNA-RISC complex be reused?

Yes it can be

What are 2 ways that RNAi can begin?

1. dsRNA is injected into a cell

2. siRNA is directly injected into a cell

What is RNAi a defense against? What is it crucial for?

Viruses and jumping genes that are crucial for plants, worms, and insects.

What type of genome do many viruses have?

dsRNA

Why is RNAi so important for worms, insects, and plants rather than humans?

This is because they lack an immune response and can’t make antibodies.

What is an example of a virus that injects dsRNA into a host?

Retrovirus

Why would we inject dsRNA into a cell?

In order to degrade or get rid of genes you don’t want

Do micro RNA genes code for proteins? If no, what do they do?

No they do not. They code for dsRNA that will destroy specific proteins or mRNA molecules at specific times.

Can dsRNA be introduced experimentally to silence genes of interest?

Yes they can be

Why does RNAi work for all animals and plants?

This is because they all have the same defense system (all have dicer and argonaute)

Is dsRNA 2 separate molecules?

Yes it is

What is shRNA?

It is an artificial RNA molecule that has a hairpin at the end that mimics a dsRNA molecule.

What is a hairpin?

It is like a loop

What does RNAi allow?

Removal of specific proteins in cells and tissues without affecting the genome

What are 2 uses of RNAi therapeutically?

1. Remove malfunctioning proteins that cause problems

2. Destroy viruses

What is one use of RNAi in terms of research?

1. Study the functions of individual proteins

What are PIEZ01 PIEZ02?

They are ion channels that sense the pressure on the membrane

What happens if you push on the membrane?

The ion channels will open and you will feel someone touching you

How did they discover PIEZ01 and PIEZ02?

By using RNAi. They removed proteins one at a time until they found the one that would inhibit that process.

What is Huntingtons disease caused by?

Mutations in huntingtin gene that causes the aggregations of gigantic balls of hunting tins proteins that are misfolded.

What happens during this aggregation of huntingtins proteins?

Neurons start to die and it causes brain damage.

How can we cure Huntingtons disease?

By using RNAi to remove huntingtins proteins

How can we determine what proteins are used to keep the cell shape?

By using RNAi to remove a bunch of proteins until you find a bunch that are required for keeping the shape of the cell.