Lecture 30: New frontiers in micro RNA therapies

Question 1

How do micro RNAs work?

Answer 1

They bind to mRNA sequence and prevent translation

Question 2

What are the characteristics of miRNA?

Answer 2

1 can bind to many mRNAs in a single pathway.

Many miRNAs can target a single mRNA

Question 3

How are miRNAs related to normal heart health?

Answer 3

miRNAs are essential for normal cardiac biology

Deregulation of miRNAs contributes toward disease (attractive therapeutic targets for disease)

Translational potential (miRNA drugs have been developed and tested in humans)

Potential therapy for heart failure

Question 4

What causes heart failure?

Answer 4

Heart failure occurs when the heart muscle has become too weak to pump blood through the body as effectively as normal.

Question 5

What is the treatment for heart failure?

Answer 5

Existing therapies slow heart failure progression but there is no cure.

Question 6

What are the types of cardiac hypertrophy?

Answer 6

Pathological (bad) and physiological (good)

Question 7

What did PI3K do to mice who had induced heart problems?

Answer 7

PI3K is protective of heart during heart attack and hypertension

Question 8

Why is PI3K protectiveness relevant for miRNA gene therapy?

Answer 8

miRNAs can be used to mimic the protective effects of PI3K

Question 9

How are miRNAs linked with pathological and physiological cardiac hypertrophy chosen?

Answer 9

They had to be decreased expression in healthy but increased in susceptible.

They had to be decreased in healthy and increased during heart failure

Question 10

How can the chosen pathological miRNA markers be used to develop a therapy?

Answer 10

Target PI3K regulated miRNAs in mouse models of heart failure

Question 11

What are antimiRs?

Answer 11

antisense oligonucleotides that either inhibit individual miRNAs or miRNA families.

Question 12

What are the chemical characteristics of LNA-antimiRs?

Answer 12

High binding affinity

Stable

No delivery vehicle

Easy formulation in saline

Negligible off-target effects

No evidence of toxicity

Chronic knockdown

Question 13

What protective effect did LNA-antimiRs have?

Answer 13

Protected against heart failure

Decreased heart weight

Decreased lung weight

Increased cardiac and electrical function

Inflammatory response is inhibited

An increase in cardiac repair and regeneration was seen

Decreased fibrosis

Question 14

Summary:

Answer 14

Inhibition of miR-34 is protective and increased heart function and lowered heart and lung weight.

Improved outcome with treatment was associated with increased expression of target genes involved in cardiac repair and electrical function of the heart

Question 15

What are some cardiac stress genes and their function in the heart?

Answer 15

Anp is a cardiac stress gene and is increased with heart and renal failure.

Serca2a is critical for contraction and relaxation (calcium channel to enter SR)

Question 16

What happened to Serca2a when miR-34 was inhibited?

Answer 16

Serca2a was increased when miR-34 was inhibited.

Question 17

What is a luciferase assay?

Answer 17

An assay that uses the glowing protein luciferase to check if there is binding going on.

Question 18

What was the result of anti miR-652?

Answer 18

Decrease in fibrosis

Improved cardiac function

Preserved angiogenesis

Less jagf 1 was produced resulting in less cardiac hypertrophy

Question 19

Are LNA inhibtors tissue specific? What does this tell us?

Answer 19

LNA inhibitors are not tissue specific. In other tissue miR-34 and miR-652 are decreased. Adverse effects could occur in other tissue.

Question 20

What are functions of miR-34 in other tissue?

Answer 20

Key regulators of skeletogenesis

important for long-term maintenance of the brain

modulate tumour progression

Question 21

How can LNA inhibitors be made more tissue specific (to the heart)?

Answer 21

using an AAV serotype (AAV6 goes to heart and skeletal muscle in combination with a CMV promoter)

Promoter

Inclusion of reporter gene (expressed when miRNA is taking action)