Flashcards in Cardio 9 Deck (20):
What are miRNAs?
Short, non-coding RNA molecules, involved in many biological processes
Where do miRNAs bind?
Complementary 3’UTR of multiple target mRNAs (seed)
What is the seed region?
8bp long is complementary to a target region of the mRNA - causes mRNA degradation - human diseases
What does dicer do?
Makes miRNAs in mice hearts
What happens if dicer is absent?
Mice without dicer had an enlarged heart - heart pathology - hearts were dilates (thin walls) - dilated cardiomyopathy (heart disease), impaired pump ability, premature death
What is heart failure?
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
What are the features of PI3K?
- 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
When are miR-34 and miR-652 increased and reduced?
Reduced in physiologic hypertrophy and increased in diseased heart
What does miR-34 cause?
Heart attack, tumour progression
What are the features of luciferase?
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
What do miRNA spinges contain?
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
How many binding sites in sponges?
What are the features of AAV6?
AAV6 – transduces heart and skeletal muscle in combination with CMV promoter. 4nt spacer to optimise binding and reduce formation of secondary structures
What are the features of LNA-antimiRs (miRNA inhibitors)?
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
What does antimir (miR-652) reduce?
-Heart, lung and atria size
-Anp (diseased heart state)
What does antimir (miR-652) improve?
-Repair and regeneration
-JAG1 (anti hypertrophic)
What is the role of vinculin?
Cardiomyocyte stability, regulates expression of proteins in the intercalated disk
Although LNA inhibitors are not specific, do they have an effect on organ weight?
What are the pathways for physiological and pathological hypertrophy?
Physiological: IGF-1, Akt, PI3K