RNA INTERFERENCE TECHNOLOGY- GENE SLIENCING(Shooting down mRNA)

By-Somanath BaralRoll No.-BY3416M.Sc part Isb000333@gmail.com

BackgroundBackgroundWhat is it and its discovery?What is it and its discovery?The mechanism and processThe mechanism and processAdvantages of RNAi mechanism Advantages of RNAi mechanism in cell in cellConclusionConclusion

RNAiRNAi

Transcription

Translation

Shooting mRNA means RNA interference

What is RNA interference?

--Gene “knockdown”

--A cellular mechanism that degrades unwanted RNAs in the cytoplasm but not in the nucleus.

--A way for the cell to defend itself.

Jorgensen 1990van der Krol 1990

Gene injection (pigmentationEnzyme-petunias)Expectation: more red colorCo-suppression of transgene and endogenous gene.

First discovered in plants(R. Jorgensen, 1990)

RNAi discovered in C. elegans (first animal) while attempting to use antisense RNA in vivo

Craig Mello Andrew Fire (2006 Nobel Prize in Physiology & Medicine)

Control “sense” RNAs also produced suppression of target gene! sense RNAs were contaminated with dsRNA. dsRNA was the suppressing agent.

RNA interference:

--A type of gene regulation

--Involve small RNA molecules

--Induce a double stranded RNA

The RNAi process

The mechanism of small interfering RNAs (siRNAs)

What happens? dsRNA is processed into shorter units

(siRNAs) that guide the targeted cleavage of homologous RNA.

Step 1

• dsRNA is processed into sense and antisense RNAs • 21-25 nucleotides in

length • have 2-3 nt 3’

overhanging ends • Done by Dicer (an

RNase III-type enzyme)

Dicer cuts dsRNA into short RNAs

Step 2

• The siRNAs associate

with RISC (RNA- induced silencing complex) and unwind

Step 3

• the antisense siRNAs act as guides for RISC to associate with complimentary single-stranded mRNAs.

Step 4

• RISC cuts the mRNA approximately in the middle of the region paired with the siRNA

• The mRNA is degraded further

Advantages of RNAi1. The most powerful way to inhibit

unwanted gene expression and acquire info about the gene’s function fast

2. Works in any cell/organism3. Uses conserved endogenous

machinery4. Potent at low concentrations5. Highly specific.

conclusion

RNAi is a valuable research tool,both in self culture and in living organism.

Most widely held view is that RNAi evolved to protect the genome virus.

The genetic modifications of plant by different approaches have a millstone among RNAi shows the greater potentiality to for crop improvement to sustain the production and productivity.

References

1. Textbook of Genetics by Ajoy Paul2. Genetics by P.K.Gupta3. Images from Google

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