siRNA Technology

1. siRNA TECHNOLOGY
presented by
RIA DAS
M.Pharm (PHARMACOLOGY)
1st semester, 1st year
Registration Number:211002320210008
Roll Number:10020221008
Department Of Pharmaceutical Science And Technology
MAULANA ABUL KALAM AZAD UNIVERSITY OF TECHNOLOGY

2. CONTENTS:
 RNA
 What is RNA interference (RNAi)?
 siRNA
 Properties of small non-coding RNA
 Structure of siRNA
 RNAi: two phases
 siRNA pathway illustration
 Function of siRNA
 Applications of siRNA
 siRNA targeting ApoB
 siRNA for treatment of AMD
 Advantages of siRNA
 Challenges
 Conclusion
 References

3. RNA:
 RNA or Ribonucleic Acid is a polymer essential in various biological roles in coding,
decoding, regulation, and expression of genes.
 It is made up of Ribose sugar, phosphate, and nitrogenous bases Adenine, Guanine,
Cytosine and Uracil.

4. What is RNA interference (RNAi)?
 “The process by which dsRNA silences gene expression”
 RNAi is the mechanism that inhibits gene expression at a stage of translation or by
hindering the transcription of specific genes.
 Highly specific process.
 Very potent activity.
 RNAi targets include RNA from viruses and transposons.
 Two types of small RNA molecules - miRNA and siRNA are central to RNA
interference.

5. siRNA:
 siRNA or Small interfering RNA or sometimes known as short interfering RNA or
silencing RNA.
 Class of double stranded RNA.
 Non-coding RNA molecules.
 Typically 20-24 base pairs in length.
 It interferes with the expression of specific genes with complementary nucleotide
sequences by degrading mRNA after transcription, preventing translation.

6. Properties of small non-coding RNA:
 Involved in silencing of other mRNA transcripts.
 Silences an mRNA by base pairing with some sequence on the mRNA.
 Usually they are only about 20-24 nucleotides long.
 Synthesized by first cutting up longer precursor sequences.

7. Structure of siRNA:
 Naturally occurring siRNAs have a well defined structure.
 It is short, usually of 20-24 base pairs.
 Double stranded RNA.
 Phosphorylated 5’ ends, and hydroxylated 3’ ends.

8. RNAi: two phases
 Initiation
 Generation of mature siRNA.
 Execution
 Silencing of target gene.
 Degradation or inhibition of translation.

9. siRNA pathway illustration:

10. Function of siRNA:
 Maintain genome integrity against foreign RNA molecules.
 As therapeutic agent.

11. Applications of siRNA:
 Basic Research:
 Determining protein function.
 Clinical Research:
 Cancer, hypercholesterolemia, infections, developmental defects.

12. siRNA targeting ApoB:
 ApoB, a liver enzyme essential for assembly and secretion of low-density lipoprotein
(LDL).
 It is required for metabolism of cholesterol.
 High levels of ApoB and LDL increase the risk of coronary artery disease.
 Cholesterol-conjugated siRNA targets ApoB enzyme and checks the enzyme
production.
 Alnylam Pharmaceuticals developed siRNA to target ApoB and demonstrated the
production effect on mice first.

13. siRNA for treatment of AMD:
 Age-related macular degeneration (AMD) is an eye disease that destroys central vision
by damaging macula, the central region of retina.
 Patients may develop a blank or blind spot in their central field of vision.
 Objects may appear distorted or smaller than they really are.
 Straight lines may appear wavy or curved.
 There are no effective therapies.
 AMD is often associated and prompted by neovascularization.
 Macular neovascularization is stimulated by interaction of vascular endothelial growth
factor (VEGF) with vascular endothelial growth factor receptor (VEGFR-1).
 Inhibiting production of VEGFR-1 should stop neovascularization and prevent AMD.

14. Advantages of siRNA:
 Cost effective.
 Highly specific method.
 Regulation of target gene.
 Helpful tool for gene function analysis.
 Helpful in gene therapy.

15. Challenges:
 Not been fully approved in clinical practice.
 Patient might develop an immune response against the therapy.
 Target delivery.
 Off-target effects.

16. Conclusion:
 siRNA have become not only an exciting new tool in molecular biology, but also the
next frontier in molecular medicine.
 Significant hurdles remain, most notably guaranteeing specificity and finding safe and
efficacious delivery system.
 Work is ongoing to solve these problem, but the therapeutic promise of siRNA remains
great.

17. References:
 Khvorova, A., Reynolds, A. and Jayasena, S.D. (2003) Functional siRNAs and miRNAs
exhibit strand bias. Cell 115, 209–216.
 Morris, K.V., Chan, S.W., Jacobsen, S.E. and Looney, D.J. (2004) Small interfering
RNA-induced transcriptional gene silencing in human cells. Science 305, 1289–1292.
 Kawasaki, H. and Taira, K. (2004) Induction of DNA methylation and gene silencing by
short interfering RNAs in human cells. Nature 431, 211–217.
 Reynolds, A. et al. (2004) Rational siRNA design for RNA interference. Nat.
Biotechnol. 22, 326–330.