cisregulatorische

cisregulatorische (cis-regulatory) refers to DNA sequences that regulate the expression of nearby genes on the same DNA molecule. These elements do not code for proteins themselves but influence when, where, and how much a gene is transcribed.

Typical cis-regulatory elements include promoters, enhancers, silencers, insulators, and regulatory motifs in untranslated regions or introns. Promoters are located close to transcription start sites and help recruit RNA polymerase II. Enhancers and silencers can act at a distance, sometimes thousands of base pairs away, by looping the DNA to contact the promoter and modulating transcription levels. Insulators define regulatory boundaries and can block interactions between enhancers and non-target promoters.

Mechanism: cis-regulatory elements bind transcription factors and co-regulators, recruit chromatin-modifying enzymes, and influence the chromatin state. This regulates the assembly of the transcriptional machinery and affects initiation and, in some cases, elongation of transcription.

Evolution and research: changes in cis-regulatory sequences can alter gene expression patterns and contribute to evolution without changing coding sequences. Investigations use approaches such as ChIP-seq, ATAC-seq or DNase I hypersensitivity assays, reporter assays, massively parallel reporter assays, and genome editing techniques to test function.

Relation to trans-regulatory control: cis elements act in cis, affecting only genes on the same DNA molecule, whereas trans-acting factors are diffusible proteins that can regulate multiple genes across the genome. Together, cis and trans regulation shape spatial and temporal expression patterns across tissues and developmental stages.