Modulations of hMOF autoacetylation by SIRT1 regulate hMOF recruitment and activities on the chromatin

Abstract

A wide variety of nuclear regulators and enzymes are subjected to acetylation of the lysine residue, which regulates different aspects of protein functions. The MYST family histone acetyltransferase, human ortholog of MOF (hMOF), plays critical roles in transcription activation by acetylating nucleosomal H4K16. In this study, we found that hMOF acetylates itself in vitro and in vivo, and the acetylation is restricted to the conserved MYST domain (C2HC zinc finger and HAT), of which the K274 residue is the major autoacetylation site. Furthermore, the class III histone deacetylase SIRT1 was found to interact with the MYST domain of hMOF through the deacetylase catalytic region and deacetylate autoacetylated hMOF. In vitro binding assays showed that non-acetylated hMOF robustly binds to nucleosomes while acetylation decreases the binding ability. In HeLa cells, the recruitment of hMOF to the chromatin increases in response to SIRT1 overexpression and decreases after knockdown of SIRT1. The acetylation mimic mutation K274Q apparently decreases the chromatin recruitment of hMOF as well as the global H4K16Ac level in HeLa cells. Finally, upon SIRT1 knockdown, hMOF recruitment to the gene body region of its target gene HoxA9 decreases, accompanied with decrease of H4K16Ac at the same region and repression of HoxA9 transcription. These results suggest a dynamic interplay between SIRT1 and hMOF in regulating H4K16 acetylation.

Quantitative Acetylome Analysis Reveals the Roles of SIRT1 in Regulating Diverse Substrates and Cellular Pathways

“…We extracted all of the lysine N-acetyltransferases identified in our data set ( Table I) and discovered that acetylation levels of the MYST acetyltransferase family were most affected by SIRT1 knockout. This result is in agreement with previous findings that Kat5 (Tip60) and Kat8 (Myst1), two of the MYST family proteins, are SIRT1 substrates that are negatively regulated by SIRT1 (33)(34)(35)(36). Moreover, we showed that Ing3, a known member of Kat7 (Myst2) protein complex, demonstrates an over 10-fold increase in acetylation level at two sites (K181, K264) in SIRT1 knockout cells.…”

Regulation of the histone acetyltransferase activity of hMOF via autoacetylation of Lys274

“…Recently the Akhtar and Liu groups also report that hMOF can be autoacetylated at Lys274 [5,8]. Compared with their studies, our work reveals that hMOF is autoacetylated in an intra-molecular manner, indicates that the autoacetylation of hMOF at Lys274 has a significant impact on the catalytic activity of the enzyme, and provides the structural basis for the modulation of the enzymatic activity by Lys274 acetylation.…”

Sirt1 ablation promotes stress-induced loss of epigenetic and genomic hematopoietic stem and progenitor cell maintenance

“…The closest mammalian Sir2 ortholog, Sirt1, is further involved in the transcriptional regulation of several key developmental regulators (Calvanese et al, 2010;Haigis and Sinclair, 2010;Lu et al, 2011) and was reported to associate with the stem cell-specific Polycomb group (PcG) repressive complex PRC4, preferentially under conditions of oxidative stress (Kuzmichev et al, 2005;O'Hagan et al, 2011). Consistent with a role for Sirt1 in stem cell homeostasis, Sirt1-deficient embryonic stem (ES) cells show increased sensitivity to oxidative stress, DNA damage accumulation, and genomic instability (Oberdoerffer et al, 2008; cues (Narala et al, 2008;Leko et al, 2012;Matsui et al, 2012;Peled et al, 2012).…”