Role of Jade-1 in the Histone Acetyltransferase (HAT) HBO1 Complex

Abstract

Regulation of global chromatin acetylation is important for chromatin remodeling. A small family of Jade proteins includes Jade-1L, Jade-2, and Jade-3, each bearing two mid-molecule tandem plant homology domain (PHD) zinc fingers. We previously demonstrated that the short isoform of Jade-1L protein, Jade-1, is associated with endogenous histone acetyltransferase (HAT) activity. It has been found that Jade-1L/2/3 proteins co-purify with a novel HAT complex, consisting of HBO1, ING4/5, and Eaf6. We investigated a role for Jade-1/1L in the HBO1 complex. When overexpressed individually, neither Jade-1/1L nor HBO1 affected histone acetylation. However, co-expression of Jade-1/1L and HBO1 increased acetylation of the bulk of endogenous histone H4 in epithelial cells in a synergistic manner, suggesting that Jade1/1L positively regulates HBO1 HAT activity. Conversely, small interfering RNA-mediated depletion of endogenous Jade resulted in reduced levels of H4 acetylation. Moreover, HBO1-mediated H4 acetylation activity was enhanced severalfold by the presence of Jade-1/1L in vitro. The removal of PHD fingers affected neither binding nor mutual Jade-1-HBO1 stabilization but completely abrogated the synergistic Jade-1/ 1L-and HBO1-mediated histone H4 acetylation in live cells and in vitro with reconstituted oligonucleosome substrates. Therefore, PHDs are necessary for Jade-1/1L-induced acetylation of nucleosomal histones by HBO1. In contrast to Jade-1/1L, the PHD zinc finger protein ING4/5 failed to synergize with HBO1 to promote histone acetylation. The physical interaction of ING4/5 with HBO1 occurred in the presence of Jade-1L or Jade-3 but not with the Jade-1 short isoform. In summary, this study demonstrates that Jade-1/1L are crucial co-factors for HBO1-mediated histone H4 acetylation.Gene for apoptosis and differentiation-1, Jade-1 (PHF17), has been identified as a protein interacting with the von Hippel Lindau gene product by a yeast two-hybrid approach (1). The 509-amino acid Jade-1 protein contains one canonical Cys 4 HisCis 3 plant homology domain (PHD) 2 followed by a noncanonical extended PHD domain, which are zinc-binding motifs. Most PHD family proteins are localized to the cell nucleus and are associated with chromatin, chromatin-modifying enzymes, and transcription factors (2, 3). We recently reported that endogenous Jade-1 is localized to the cell nucleus and that ectopically expressed Jade-1 possesses intrinsic transcriptional activity (4). Most importantly, we demonstrated that Jade-1 can promote endogenous histone H4 acetylation by associating with a histone H4-specific endogenous HAT. Interestingly, the histone H4-specific HAT, TIP60, interacted with Jade-1 physically and functionally in vitro and in live cells.Gene data base analysis revealed two other Jade-1 homologs, Jade-2 (PHF15) and Jade-3 (PHF16). Jade-3 has been previously identified by screening genes induced by steroid hormones in breast cancer cells (5). Jade-1 mRNA gives rise to two protein products, the full-length Jade-1L consisting of ...

Conserved Molecular Interactions within the HBO1 Acetyltransferase Complexes Regulate Cell Proliferation

“…1B and 2A). These data also confirm that the shorter JADE1S isoform does not associate with ING proteins in vivo (12,53).…”

“…Subsequently, it became clear that HBO1 could also associate with a shorter isoform of JADE1, named JADE1S ( Fig. 2A) (12,53). In fact, the bulk of functional information on JADE1 in the literature is based on this smaller 509-amino-acid protein produced by an abundant mRNA splice variant (40,(74)(75)(76).…”

Exchange of associated factors directs a switch in HBO1 acetyltransferase histone tail specificity

“…We and others have shown that the HBO1 enzyme is purified with JADE scaffold proteins and is responsible for histone H4 tail acetylation (Doyon et al 2006;Iizuka et al 2006Iizuka et al , 2008Foy et al 2008;Miotto and Struhl 2010). We even showed that HBO1 siRNA-mediated knockdown in HeLa cells leads to a global loss of H4 acetylation on Lys5, Lys8, and Lys12, matching in vitro specificity on chromatin and arguing that HBO1 was the main H4-specific HAT in mammals (Doyon et al 2006).…”

Histone target selection within chromatin: an exemplary case of teamwork

“…For instance, PZP (PHD-Zn knuckle-PHD) domains are present in the scaffold proteins BRPF/JADE of HBO1 and MOZ/MORF HAT complexes. This domain acts as a single functional entity and is essential for chromatin binding and acetylation by these complexes both in vivo and in vitro (Foy et al 2008;Saksouk et al 2009;Avvakumov et al 2012;Lalonde et al 2013). The binding mechanism appears to occur through coordinated association of the PZP with histone H3 N-terminal tails and nucleosomal DNA (Saksouk et al 2009;Liu et al 2012;Lalonde et al 2013).…”