Cardio 9

Question 1

What are miRNAs?

Answer 1

Short, non-coding RNA molecules, involved in many biological processes

Question 2

Where do miRNAs bind?

Answer 2

Complementary 3’UTR of multiple target mRNAs (seed)

Question 3

What is the seed region?

Answer 3

8bp long is complementary to a target region of the mRNA - causes mRNA degradation - human diseases

Question 4

What does dicer do?

Answer 4

Makes miRNAs in mice hearts

Question 5

What happens if dicer is absent?

Answer 5

Mice without dicer had an enlarged heart - heart pathology - hearts were dilates (thin walls) - dilated cardiomyopathy (heart disease), impaired pump ability, premature death

Question 6

What is heart failure?

Answer 6

Heart failure occurs when the heart muscle has become too weak to pump blood through the body as effectively as normal – common endpoint for CVD and causes breathlessness and hinders day-day activities

Question 7

What are the features of PI3K?

Answer 7

• PI3K is cardioprotective. Protects from cardiac disease, dysfunction and failure
• Prevents excessive heart growth, heart dysfunction and fibrosis
• PI3K activity increased (physiological hypertrophy) - subjected to MI - generate a spectrum of heart phenotypes

Question 8

When are miR-34 and miR-652 increased and reduced?

Answer 8

Reduced in physiologic hypertrophy and increased in diseased heart

Question 9

What does miR-34 cause?

Answer 9

Heart attack, tumour progression

Question 10

What are the features of luciferase?

Answer 10

Enzyme produced by fireflies - can be used to validate targets - luciferase emits light if there is no binding and if there is binding there will be reduced light and luciferase

Question 11

What do miRNA spinges contain?

Answer 11

Multiple miRNA binding sites which act as competitive inhibitors for miRNA binding
- Sponges are designed to include 4-10 multiple binding sites to sequester miRNAs

Question 12

How many binding sites in sponges?

Answer 12

4-10

Question 13

What are the features of AAV6?

Answer 13

AAV6 – transduces heart and skeletal muscle in combination with CMV promoter. 4nt spacer to optimise binding and reduce formation of secondary structures

Question 14

What are the features of LNA-antimiRs (miRNA inhibitors)?

Answer 14

Chemically modified antisense oligonucleotides that can inhibit miRNAs (bind to them to stop them interrupting mRNA)

High binding affinity, stable, no delivery vehicle, easy formulation in saline, negligible off-target effects, no evidence of toxicity, chronic knockdown

Question 15

What does antimir (miR-652) reduce?

Answer 15

• miRNA expression
• Heart, lung and atria size
• Fibrosis
• Anp (diseased heart state)
• Cell size
• Cell death
• Bax (apoptosis)
• Inflammation
• luciferase (accurate)

Question 16

What does antimir (miR-652) improve?

Answer 16

• Electrical function
• Repair and regeneration
• Gene expression
• Cardiac function
• Coronary angiogenesis
• JAG1 (anti hypertrophic)

Question 17

What is the role of vinculin?

Answer 17

Cardiomyocyte stability, regulates expression of proteins in the intercalated disk

Question 18

Although LNA inhibitors are not specific, do they have an effect on organ weight?

Answer 18

No

Question 19

What are the pathways for physiological and pathological hypertrophy?

Answer 19

Physiological: IGF-1, Akt, PI3K
Pathological: GPCR

Question 20

What are the key regulators of skeletogenesis?

Answer 20

miR-34b miR-34c