hMOF Acetylation of DBC1/CCAR2 Prevents Binding and Inhibition of SirT1

Abstract

The NAD؉ -dependent deacetylase SirT1 regulates gene silencing and genomic stability in response to nutrient deprivation and DNA damage. An important regulator of SirT1 in mammalian cells is DBC1 (deleted in breast cancer 1; KIAA1967 or CCAR2), which binds to SirT1 and inhibits the deacetylation of substrates. Recent studies have revealed that ATM/ATR-mediated phosphorylation of DBC1 promotes binding to SirT1. Here we show that DBC1 is modified by acetylation on two N-terminal lysine residues (K112 and K215). The MYST family histone acetyltransferase hMOF (human MOF) is responsible for DBC1 acetylation. Acetylation of K112 and K215 inhibits DBC1-SirT1 binding and increases SirT1 deacetylase activity. SirT1 also promotes DBC1 deacetylation, suggesting the presence of a negative-feedback mechanism that stabilizes the SirT1-DBC1 complex and limits SirT1 activity. hMOF binding and acetylation of DBC1 are inhibited after DNA damage in an ATM-dependent fashion, contributing to increased SirT1-DBC1 binding after DNA damage. Furthermore, a DBC1 mutant that mimics the acetylated state fails to promote apoptosis after DNA damage. These results suggest that acetylation of DBC1 inhibits binding to SirT1 and serves as a mechanism that connects DNA damage signaling to SirT1 and cell fate determination.

GATA1 induces epithelial-mesenchymal transition in breast cancer cells through PAK5 oncogenic signaling

“…Recent studies have revealed that ATM/ATR-mediated phosphorylation of DBC1 promotes binding to SirT1 [ 34 ]. Phosphorylation of RUNX1 by CDK reduces direct interaction with HDAC1 and HDAC3 [ 35 ].…”

Acetylation of CCAR2 Establishes a BET/BRD9 Acetyl Switch in Response to Combined Deacetylase and Bromodomain Inhibition

“…Immunoprecipitation (IP) methodologies were as reported for endogenous proteins (10,11), or Myc-, GST-, and HA-tagged proteins (5,(25)(26)(27).…”

“…Acetylation sites on CCAR2 were identified following the general approach reported previously (5). In brief, 24 hours after seeding, HCT116 cells were treated with sulforaphane or DMSO, and 6 hours later the cell lysates were subjected to IP using CCAR2 antibody.…”

“…Cell cycle and apoptosis regulator 2 (CCAR2), also known as DBC1/KIAA1967, has gained attention as a "master regulator" of metabolism, aging, and cancer (1)(2)(3)(4). This designation derives from the interactions of CCAR2 with protein partners that exert critical roles in physiology and pathophysiology, including Sirtuin 1 (SIRT1) and CHK2, linking CCAR2 to p53 function and DNA repair (1)(2)(3)(4)(5)(6)(7). Less is known about the N-terminal region of CCAR2 that associates with, and inhibits, histone deacetylase 3 (HDAC3), while also interacting with b-catenin to stabilize b-catenin/Tcf complexes in the nucleus (6,7).…”

Dephosphorylation of DBC1 by Protein Phosphatase 4 Is Important for p53-Mediated Cellular Functions

“…To prevent these detrimental consequences, eukaryotic cells have evolved an elaborate and complex response system called DNA damage response (DDR), which is mostly initiated by the phosphatidylinositol 3-kinase (PI3)-like family of kinases, including DNA-dependent protein kinase (DNA-PK) catalytic subunit, ataxia telangiectasia mutated (ATM), and ataxia telangiectasia-and Rad3-related (ATR) ( Ciccia and Elledge, 2010 ; Lee and Chowdhury, 2011 ; Matsuoka et al, 2007 ; Mu et al, 2007 ; Smith et al, 2010 ). Recently, DBC1 (also named p30 DBC, KIAA1967, or CCAR2) was identified as a new target of ATM/ATR kinases ( Zannini et al, 2012 ) and it plays a critical role in maintaining genomic stability and cellular integrity following genotoxic stress ( Kim et al, 2008 ; 2009a ; Magni et al, 2014 ; Park et al, 2014 ; Zannini et al, 2012 ; Zheng et al, 2013 ). Upon DNA damage conditions, DBC1 on Thr454 is phosphorylated, which promotes acetylation-mediated p53 activation through inducing the interception of NAD-dependent deacetylase sirtuin-1 (SIRT1) from p53 and triggers apoptosis.…”