SIRT6 is critical for activating transcription of Nuclear factor (erythroid-derived 2)-like 2 (NRF2) responsive genes during oxidative stress. However, while the mechanism of SIRT6-mediated silencing is well understood, the mechanism of SIRT6-mediated transcriptional activation is unknown. Here, we employed SIRT6 separation of function mutants to reveal that SIRT6 mono-ADP-ribosylation activity is required for transcriptional activation. We demonstrate that SIRT6 mono-ADP-ribosylation of BAF170, a subunit of BAF chromatin remodeling complex, is critical for activation of a subset of NRF2 responsive genes upon oxidative stress. We show that SIRT6 recruits BAF170 to enhancer region of the Heme oxygenase-1 locus and promotes recruitment of RNA polymerase II. Furthermore, SIRT6 mediates the formation of the active chromatin 10-kb loop at the HO-1 locus, which is absent in SIRT6 deficient tissue. These results provide a novel mechanism for SIRT6-mediated transcriptional activation, where SIRT6 mono-ADP-ribosylates and recruits chromatin remodeling proteins to mediate the formation of active chromatin loop.
Published by Oxford University Press on behalf of Nucleic Acids Research 2019.