Hypoxia and Chromatin: A Focus on Transcriptional Repression Mechanisms.

Hypoxia or reduced oxygen availability has been studied extensively for its ability to activate specific genes. Hypoxia-induced gene expression is mediated by the HIF transcription factors, but not exclusively so. Despite the extensive knowledge about how hypoxia activates genes, much less is known about how hypoxia promotes gene repression. In this review, we discuss the potential mechanisms underlying hypoxia-induced transcriptional repression responses. We highlight HIF-dependent and independent mechanisms as well as the potential roles of dioxygenases with functions at the nucleosome and DNA level. Lastly, we discuss recent evidence regarding the involvement of transcriptional repressor complexes in hypoxia.