gene knockdown, knockout, gene silencing

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Liau
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gene knockdown, knockout, gene silencing

Post by Liau » Thu Jun 15, 2006 3:49 am

I hv checked wikipedia, but i still do not understand the differences between gene knockdown, knockout and gene silencing. Anyone please help me. thanks.

weesper
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Post by weesper » Thu Jun 15, 2006 12:00 pm

Okay the differences are subtle but impt; gene knockout is where a gene is completely 'erased' from the genome this usually occurs thorugh of prces of homologous recombination or CRE-Lox excision (you can look this up in wikipedia) where a sequence of gene X, say the ATG transcription start site is exchanged for a neutral sequence. As a consequence, after recombination, there is 0% of the gene product and this is called a 'knockout'

Now knockdown occurs through a different process where you introduce short RNA sequences homologous to your target gene RNA sequence in a cell and through specific binding the RNA sequences coding for your gene will be depleted; however the original gene sequence in the genome is still there and because this method is not 100% effective but at the most 90% of you target RNA will be depleted, this is referred to as knockDOWN instead of knockOUT.

Because doing a knockdown can give you an approximation of what your phenotype after knockout may look like ('is the pathway on' questions like this) and because one can usually do it in a week where a knockout in a cell line will take you al least a couple of months, researchers usually do a knockdown first and if necessary to prove their point or have a continuous supply of cells to work with they'll create a knockout.

Gene silencing is the same as knockdown. Hope this helps take care weesper

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