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Transcript of microRNA therapeutics
Shravan Morla 2011A5TS698H
Srividya Myneni 2011A5TS096H
• Introduction of microRNA
• Discovery of microRNA
• Micro RNA biogenesis
• Mechanism of action of microRNA
• miRNAs are non-coding RNAs found only ineukaryotes
• Single stranded and small in size (˷22 nt long)
• Comprise one of the more classes of gene regulatorymolecules
• Play important regulatory roles in animals and plantsby targeting mRNAs for cleavage or translationalrepression
Discovery of miRNA
• The first miRNA was discovered in 1993 during a study of the lin-4gene, which was known to control the timing of C. elegans larvaldevelopment by repressing the lin-14 gene.
• When they isolated the lin-4 gene, they found that instead ofproducing an mRNA encoding a protein, it produced shortnoncoding RNAs, one of which was a ~22-nucleotide RNA thatcontained sequences partially complementary to multiplesequences in the 3' UTR of the lin-14 mRNA.
• This complementarity was proposed to inhibit the translation of thelin-14 mRNA into the LIN-14 protein
• At the time, the lin-4 small RNA was thought to be a nematodeidiosyncrasy.
• Only in 2000 was a second small RNA characterized: let-7 RNA,which represses lin-41 to promote a later developmental transitionin C. elegans.
• The let-7 RNA was soon found to be conserved in many species,leading to the suggestion that let-7 RNA and additional "smalltemporal RNAs" might regulate the timing of development indiverse animals, including humans.
• A year later, the lin-4 and let-7 RNAs were found to be part of a verylarge class of small RNAs present in C. elegans, Drosophila andhuman cells.
• The many newly discovered RNAs of this class resembled the lin-4and let-7 RNAs, except their expression patterns were usuallyinconsistent with a role in regulating the timing of development,which suggested that most might function in other types ofregulatory pathways. At this point, researchers started using theterm “microRNA” to refer to this class of small regulatory RNAs.
TranscriptionRNA Polymerase II
Drosha and DGCR8 complex
Pre-miRNA moves to the cytoplasm
miRNA mechanism of action
Fig: Biogenesis and MOA of microRNA.
Source: Eva van Rooij, Sakari Kauppinen. Development of microRNA therapeutics iscoming of age. EMBO Mol Medicine. 2014 Jun 16
Mechanism of miRNA
Micro RNA therapeutics
• miRNA Mimics
Micro RNA therapeutics
o Target Occupiers
Delivery of miRNA
PHYSICAL APPROACHES FOR miRNADELIVERY
• 2′-OMe–modified oligoribonucleotides (2′-OMes)
• cholesterol moiety–conjugated 2′-OMes
• LNA(locked nucleic acid)
• oligonucleotides containing 2′-MOE, 2′-flouro (2′-F), and phosphorothioate backbone modifications.
• peptide nucleic acids.
• Gene gun system
• Electro-transfer(cyanine 5′–labeled molecules)
• Exosome like nanovesicles
• Nanocapsules, Nanoparticles, and Nanospheres
Electro-transfer of antimiR’s
• Cell penetrating peptide(CPP) conjugation
(penetratin, transportan, tetra-lysine, arginineoligomers)
• Peptide Nucleic Acids
(sugar-phosphate backbone is replaced by N-(2-aminoethyl) glycine units)
VIRAL VECTOR-BASED miRNA DELIVERY AND EXPRESSION• Retro viral vectors
• Lenti viral vectors
• Adenoviral vectors
miRNA’s in clinical studies
• MiR-122 (Hepatitis C Virus)
• MiR-155 (Inflammatory Disease)
• MiR-21 (Fibrosis)
• MiR-92a( Neoangiogenesis)
• MiR-33 (Metabolic Disease)
• MiR-451 (Myeloproliferative Disease)
• MiR-15 (Cardiac Regeneration and Injury)
MicroRNA expression in human cancer
• oncogenes or oncosuppressor genes
o Presence of miR‐15a and miR‐16‐1 instead of tumorsupressor gene in deleted chromosome in CLL
o Increased expression of the microRNA
Tumor supressor gene is not all expressed because of inhibition by miRNA.
o cell migration and metastasis
Role of microRNAs in cancer
• Regulator of fatty-acid metabolism
• MiR-122 - hepatocellular carcinoma
• Regulation of hepatitis C virus replication
• Hematopoiesis & Immune system
• Cardiovascular diseases
• Lymphocyte malignancies
• First microRNA as an oncomir
• MiR-21- failing murine and human heart
• chemically modified and cholesterol-conjugated miRNA inhibitors (antagomirs) was shown to inhibit interstitial fibrosis and improve cardiac function
• miR-92a in acute myeloid leukaemia and acute lymphoblastic leukaemia
• miR-92 hepatocellular Cancer
• MiR-92a in neoangiogenesis
• Lipid metabolism
o Cholesterol and HDL generation
o Fatty acid degradation
o MiR-33 & miR-122 in metabolic disordersand cardiovascular diseas
• miR-451- hematocrit(erythroid differentiation defect) -ineffective erythropoiesis
Challenges for Micro RNA therapy
• Numerous molecular targets for miRNA
• Degradation by nucleases and phosphodiesterases
• Optimal chemistry and delivery systems have to be developed.
References• E. van Rooij, A.L. Purcell, A.A. Levin, Developing
microRNA therapeutics, Circulation research, 110 (2012) 496-507.
• E. van Rooij, W.S. Marshall, E.N. Olson, Toward MicroRNA–Based Therapeutics for Heart Disease The Sense in Antisense, Circulation research, 103 (2008) 919-928.
• M.S. Ebert, J.R. Neilson, P.A. Sharp, MicroRNA sponges: competitive inhibitors of small RNAs in mammalian cells, Nature methods, 4 (2007) 721-726.