gene silencing

Gene silencing is shutting a gene up — keeping it from making its product, sometimes briefly and sometimes for the life of the cell and its descendants. Where ordinary regulation might dim a gene, silencing aims to mute it.

Cells silence genes in two broad ways. One acts on the RNA: small RNAs guide the cell to destroy a gene's messenger or block its translation, so even a transcribed gene yields no protein. The other acts on the DNA and its packaging: chemical tags such as methyl groups and tightened chromatin lock a gene away so it cannot even be transcribed. These epigenetic forms of silencing can be remarkably stable and heritable through cell division.

Silencing is essential housekeeping. It switches off genes a particular cell does not need, defends against viruses and roaming genetic elements, and balances dosage between chromosomes. Researchers also harness it deliberately — designing small RNAs to silence a chosen gene is a standard laboratory tool and the basis of some medicines.