ROLE OF MICRO-RNA IN CARDIOVASCULAR BIOLOGY

I N S T I T U T E O F B I O C H E M I S T RY A N D B I O T E C H N O L O G Y

U N I V E R S I T Y O F T H E P U N J A B L A H O R E

PRESENTED BY: BASIT JABBAR

ROLL # 03

M.S. BIOTECHNOLOGY

06-05-2014

CONTENTS• What are micro-RNAs ? • Biogenesis and Mode of Action• Cardiac Development• Dilated cardiomyopathy• Angiogenesis• Cardiac hypertrophy• Atherosclerosis• Arrhythmias• Micro-RNA based therapies for cardiovascular

diseases• Potential Challenges in micro-RNA based

therapy

MICRO-RNA

• Belong to family of non-coding RNAs

• Endogenous, short (between 19 and 25 nucleotides long)

• Negative regulators of gene expression (post-transcriptional gene silencing)

• Involved in the most important cellular processes including cell growth, differentiation and apoptosis

Santovito et al., 2012. MicroRNAs and atherosclerosis: New actors for an old movie. Nut. Met.& C.D. 22 ,937-943.

BIOGENESIS AND MODE OF ACTION

Georgia & Despina, 2012. Micro-RNAs: New Biomarkers and Novel Applications for Heart Disease Prevention and Treatment, Hosp. Chron. 7, 9–15

MICRO-RNA AND CARDIOVASCULAR SYSTEM

• The cardiovascular system- transports nutrients and removing gaseous waste from the body

• Comprised of the heart, blood vessels and blood

• Cardiovascular disease is the leading cause of mortality in developed countries

• miRNAs are known to be aberrantly expressed in the cardiovascular system under some pathological conditions

• An altered expression profile of genes that are important for cardiac function

MICRO-RNA IN CARDIAC DEVELOPMENT

The most abundant miRNAs in heart are:

•miR-1• let-7•miR-133•miR-126-3p•miR-143•miR-30c•miR-22

MICRO-RNA IN CARDIAC DEVELOPMENT

Studying the role of micro-RNAs in Cardiac development

Model organisms:

Mice, Zebrafish

etc.

Creating mutation

in particular

gene

Observing the effect

DILATED CARDIOMYOPATHYKnocking out Dicer

impaired angiogenesis

under-development of the ventricular

walls

Deletion of dgcr8 gene

left ventricular malfunction

dilated cardiomyopathy

Rao et al., 2009. Loss of cardiac microRNA-mediated regulation leads to dilated cardiomyopathyand heart failure. Circ Res. 105, 585–594.

Due to dilated left ventricle, the heart becomes unable to pump sufficient blood around the body.

ANGIOGENESIS• Sprouting of new blood vessels from pre-existing ones

• A normal and vital process in growth and development

• Also, wound healing and in the formation of granulation tissue

• Also required for the growth of the cancerous tissue

ANGIOGENESIS

PROANGIOGENIC mi-RNAslet7f, miR-27b, miR-126, miR-130a, miR-210, and miR-378

ANTIANGIOGENIC mi-RNAs miR-15/16, miR-20a/b, miR-92a, and miR-221/222

ANGIOGENESIS

Silencing of two key enzymes

Dicer and Drosha in murine

endothelial cells

Reduction of endothelial let-7f and miR-27b

Reduced capillary

sprouting and tube forming

ability

Kuehbacher et al., 2007. Role of Dicer and Drosha for endothelial microRNA expression and angiogenesis. Cir Res. 101,59–68.

CARDIAC HYPERTROPHY

Animal models of cardiac

hypertrophy

Altered expression of

miRNAs

Upregulated miR-21, miR-23a, miR-24,

miR-125, miR-129...

Downregulated: miR-1,miR-133, miR-29, miR-30,

and miR-150

Increased heart size; lead to heart failure

Van Rooij et al., 2006. A signature pattern of stress-responsive microRNAs that can evoke cardiac hypertrophy and heart failure. Proc Natl Acad Sci USA.103:18255–18260.

Cheng et al., 2007. MicroRNAs are aberrantly expressed in hypertrophic heart: do they play a role in cardiac hypertrophy? Am J Pathol. 170:1831–1840.

Tatsuguchi et al., 2007. Expression of microRNAs is dynamically regulated during cardiomyocyte hypertrophy. J. Mol. Cell. Cardiol. 42, 1137–1141.

Induction of cardiac hypertrophy by miR-195. 2-week-old wild-type (WT) and transgenic mice expressing miR-195 under control of the αMHC promoter. Moderate expression levels of miR-195 (26-fold) caused cardiac hypertrophy, whereas high expression levelsof miR-195 (29-fold) caused dilated cardiomyopathy with ventricular dilation and wall thinning.

ATHEROSCLEROSIS

• Narrowing and hardening of the arteries due to build up of plaque

• Accumulation of cholesterol, triglycerides, WBCs (macrop- hages) etc..

• Involvement of miRNAs…?

Santovito et al., 2012. MicroRNAs and atherosclerosis: New actors for an old movie. Nut. Met.& C.D. 22 ,937-943.

Micrograph of an artery with atherosclerosis

Main roles for microRNAs in atherosclerotic plaque development, progression and disruption

Figure A represents a healthy artery. Figure B shows an artery with plaque build-up

ARRHYTHMIAS

• Abnormal heartbeat due to non-uniform impulse propagation

• Genetic alterations in the ion channel (Na+, K+) genes

• Leading to electrical disturbances - cardiac arrhythmias

Marban E., 2002. Cardiac channelopathies. Nat. 415, 213–218

Transmission of electrical impulses generated in SAN (pacemaker) of the heart makes atria contract first and then ventricles thus ensuring regular heart beats.

ARRHYTHMIASOver-

expression of miRNA-1

Targets GJA1(encoding connexin43, Cx43) and

KCNJ2 (encoding the K+ channel subunit,

Kir2.1)

Slowed conduction velocity and prolonged

repolarization (arrhythmia)Yang B et al., 2007. The muscle-specific

microRNA miR-1 regulates cardiac arrhythmogenic potential by targeting GJA1 and KCNJ2. Nat Med.13, 486–491.

MICRO-RNA BASED THERAPIES FOR CARDIOVASCULAR DISEASES

Antisense miRNA Oligonucleotides

• Used for downregulation of miRNAs level leading to normal expression of gene

• Applicable for cardiovascular diseases

Hutva´gner et al., 2004. Sequence-specific inhibition of small RNA function. PLos Biol.2,E98.

MICRO-RNA BASED THERAPIES FOR CARDIOVASCULAR DISEASES

miRNA Mimics

• Enhancement of miRNA expression that are downregulated in cariovascular diseases

• miR-9 is downregulated in cardiac hypertrophy

• miRNA mimic for miR-9 in cardiac hypertrophy rat model led to attenuation of cardiac hypertrophy and improvement of cardiac function

Wang K, Long B, Zhou J, Li PF. miR-9 and NFATc3 regulate myocardin in cardiac hypertrophy.J Biol Chem2010;285:11903-11912

Eva et al., 2008. Toward Micro-RNA Based Therapeutics for Heart Disease : The Sense in Antisense. Circ Res. 103, 919-928.

POTENTIAL CHALLENGES IN MICRO-RNA BASED THERAPY

CHAL

LENG

ES

Delivery of the miRNA modulator

Off-target effects of unintended or unidentified targets of a miRNA

Toxicity of the miRNA modulator

A single miRNA can have both beneficial and pathogenic effects

Eva et al., 2008. Toward Micro-RNA Based Therapeutics for Heart Disease : The Sense in Antisense. Circ Res. 103, 919-928.