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Gene silencing
From Wikipedia, the free encyclopedia
Gene silencing is a general term describing epigenetic processes of gene regulation. The term gene silencing is generally used to describe the "switching off" of a gene by a mechanism other than genetic mutation. That is, a gene which would be expressed (turned on) under normal circumstances is switched off by machinery in the cell.
Genes are regulated at either the transcriptional or post-transcriptional level.
Transcriptional gene silencing is the result of histone modifications, creating an environment of heterochromatin around a gene that makes it inaccessible to transcriptional machinery (RNA polymerase, transcription factors, etc.).
Post-transcriptional gene silencing is the result of mRNA of a particular gene being destroyed. The destruction of the mRNA prevents translation to form an active gene product (in most cases, a protein). A common mechanism of post-transcriptional gene silencing is RNAi.
Both transcriptional and post-transcriptional gene silencing are used to regulate endogenous genes. Mechanisms of gene silencing also protect the organism's genome from transposons and viruses. Gene silencing thus may be part of an ancient immune system protecting from such infectious DNA elements.
There are several more terms related to specific topics of gene silencing:
Transcriptional Gene Silencing:
- Imprinting (genetics)
- paramutation
- transposon silencing
- transgene silencing
- transcriptional gene silencing
- position effect
Post-transcriptional Gene Silencing:
Cellular components of gene silencing:
- Science project: Transgenic apple varieties Approaches to preventing outcrossing – possible effects on micro-organisms
- MeSH Gene+silencing