Enhancer (genetics)

In genetics, an enhancer is a short (50–1500 bp) region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene will occur.^[1][2] These proteins are usually referred to as transcription factors. Enhancers are cis-acting. They can be located up to 1 Mbp (1,000,000 bp) away from the gene, upstream or downstream from the start site.^[2][3] There are hundreds of thousands of enhancers in the human genome.^[2] They are found in both prokaryotes and eukaryotes.^[4] Active enhancers typically get transcribed as enhancer or regulatory non-coding RNA, whose expression levels correlate with mRNA levels of target genes.^[5][6]

The first discovery of a eukaryotic enhancer was in the immunoglobulin heavy chain gene in 1983.^[7][8][9] This enhancer, located in the large intron, provided an explanation for the transcriptional activation of rearranged Vh gene promoters while unrearranged Vh promoters remained inactive.^[10] Lately, enhancers have been shown to be involved in certain medical conditions, for example, myelosuppression.^[11] Since 2022, scientists have used artificial intelligence to design synthetic enhancers and applied them in animal systems, first in a cell line,^[12] and one year later also in vivo.^[13][14]