Gene Silencing

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

conditional knockout

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

RNA interference