Gene silencing refers to the ability of a cell to prevent the expression of a particular gene
- While this occurs naturally, it can also be induced by scientists to study gene interactions and potentially treat inherited diseases
Conditional Knockouts
A gene knockout is a genetic technique whereby a specific gene is rendered inoperative within an organism
- Using the Cre-LoxP system, this gene knockout can be targeted to specific tissues within the organism (conditional knockout)
The Cre-LoxP system uses the enzyme Cre recombinase to remove genetic sequences located between two Lox sites
- Using recombinant DNA technology, LoxP sequences are inserted on either side of a gene of interest in a test animal
- The Cre gene is inserted next to a tissue-specific promoter in another test animal
- When the two animals are bred, the resulting offspring will possess LoxP sequences and a tissue-specific Cre recombinase
- The Cre recombinase will remove the gene located between the Lox sites to create a conditional knockout for further study
Creating a Conditional Knockout with the LoxP-Cre System
RNA Interference (RNAi)
Short interfering RNA (siRNA) is a double-stranded RNA molecule that is roughly 20 – 25 base pairs in length
siRNA interferes with the expression of genes by causing the mRNA transcripts to be broken prior to translation
- When the siRNA is unwound, one strand (the passenger strand) is degraded and one strand (the guide strand) remains
- The guide strand will hybridise to its complementary mRNA sequence and recruit a protein complex called RISC
- RISC (RNA induced silencing complex) will then destroy the targeted mRNA, preventing translation of the associated gene
RNA Interference with siRNA
