How can enhancers regulate gene expression from a distance?

• A. They code for proteins.
• B. They recruit repressors to silence transcription.
• C. Enhancers bound by activators loop to contact promoters via mediator/coactivator complexes, boosting transcription.
• D. They terminate transcription.

Answer: (C)

The main idea is that enhancers regulate gene expression from a distance by looping the DNA so the bound transcription factors at the enhancer can contact the promoter. When activators sit on an enhancer, they recruit mediator and other coactivator complexes, which help bring in and stabilize the RNA polymerase II machinery at the promoter. This looping bridges the gap between distant elements and hands the activating signal directly to the transcriptional start site, boosting transcription even though the enhancer is far away. Enhancers aren’t coding sequences and don’t terminate transcription; their job is to enhance initiation through these protein–DNA interactions. Repression can occur in other contexts, but the key mechanism for distance regulation is the enhancer–mediator–promoter communication via DNA looping.