The gene silencing ( gene silencing ) is a process from genetics, are actively switched off in the genes. Gene silencing is used for regulation of the activity of genes ( gene regulation ). When gene silencing the gene regulation of genetic information from DNA to mRNA ( transcriptional gene silencing ) or the subsequent translation (translation ) stored on the mRNA information into protein (post - transcriptional is through inhibition of the transfer ( transcription) gene silencing ).
Transcriptional gene silencing
Transcriptional gene silencing is a result of epigenetic changes in the DNA, in particular DNA methylation or histone modifications. By such modifications of a type Histonenden heterochromatic state is provided to the gene which it (, etc. RNA polymerase, transcription factors ) to bind the transcription denied machine. The classic example is the as position effect variegation ( PEV ) described phenomenon. It alters the chromatin state and thus controls the transcription activity of the affected gene or the gene region.
Post transcriptional gene silencing
As post-transcriptional gene silencing ( PTGS) processes the gene silencing are referred to, which take place after transcription of the genetic information from the DNA to the transmitting mRNA. Among the forms of post-transcriptional gene silencing include in particular the nonsense - mediated mRNA decay (NMD ) and RNA interference (RNAi ). During the nonsense - mediated mRNA decay primarily serves to avoid nonsense point mutations, RNA interference is a predominantly regulatory process involving specific RNA molecules such as miRNA and siRNA. The post-transcriptional gene silencing may lead to an enhanced degradation of the mRNA of a particular gene. Due to the degradation of the mRNA translation and thus the formation of the specific gene product ( usually a protein ) prevented. In addition, a gene-specific direct inhibition of translation as a result of post-transcriptional gene silencing is possible.