transrepressif

Transrepression, or “transrepressif” in French, refers to a regulatory mode in which one transcription factor modulates the activity of a second transcription factor or a group of genes indirectly, rather than binding directly to the promoter of the target gene. The transactivator or transrepressor recruits co‑repressors, chromatin‑remodeling complexes, or post‑translational modifying enzymes, thereby altering the transcriptional competence of other factors. This mechanism is widespread in eukaryotes and allows fine‑tuning of gene expression networks.

The classical example of a trans‑repressor is the mammalian E‑box binding factor HIF‑1α, which can recruit histone deacetylase complexes to down‑regulate genes ordinarily activated by the p53 pathway. In the same way, the viral protein VP16 of herpes simplex virus acts as a trans‑activator for immediate‑early genes but simultaneously interferes with host transcription factors such as NF‑κB, repressing inflammatory gene expression indirectly.

Transrepression plays a critical role in development, immune regulation, and cell cycle control. Mis‑regulation of trans‑repressors is implicated in cancers, where excessive suppression of tumor suppressor genes by overactive trans‑repressors can promote unchecked proliferation. In pharmacology, synthetic trans‑repressors are being explored to modulate pathogenic gene expression in diseases such as HIV and hepatitis.

Because transrepression relies on protein‑protein interactions and chromatin remodeling, it offers a versatile target for therapeutic intervention and a useful tool for manipulating gene expression in research laboratories.