Hypoxia stabilizes SETDB1 to maintain genome stability

Von Hippel-Lindau (VHL) is a tumor suppressor that functions as the substrate recognition subunit of the CRL2(VHL) E3 complex. While substrates of VHL have been identified, its tumor suppressive role remains to be fully understood. For further determination of VHL substrates, we analyzed the physical interactome of VHL and identified the histone H3K9 methyltransferase SETBD1 as a novel target. SETDB1 undergoes oxygen-dependent hydroxylation by prolyl hydroxylase domain proteins and the CRL2(VHL) complex recognizes hydroxylated SETDB1 for ubiquitin-mediated degradation. Under hypoxic conditions, SETDB1 accumulates by escaping CRL2(VHL) activity. Loss of SETDB1 in hypoxia compared with that in normoxia escalates the production of transposable element-derived double-stranded RNAs, thereby hyperactivating the immune-inflammatory response. In addition, strong derepression of TEs in hypoxic cells lacking SETDB1 triggers DNA damage-induced death. Our collective results support a molecular mechanism of oxygen-dependent SETDB1 degradation by the CRL2(VHL) E3 complex and reveal a role of SETDB1 in genome stability under hypoxia.

Automated summary

This study reveals the molecular mechanism of oxygen-dependent degradation of SETDB1 by the CRL2(VHL) E3 complex and its role in genome stability under hypoxic conditions. Loss of SETDB1 leads to the accumulation of transposable element-derived double-stranded RNAs and triggers an immune-inflammatory response and DNA damage-induced cell death.