Crosstalk between NSL Histone Acetyltransferase and MLL/SET Complexes: NSL Complex Functions in Promoting Histone H3K4 Di-Methylation Activity by MLL/SET Complexes

Abstract

hMOF (MYST1), a histone acetyltransferase (HAT), forms at least two distinct multiprotein complexes in human cells. The male specific lethal (MSL) HAT complex plays a key role in dosage compensation in Drosophila and is responsible for histone H4K16ac in vivo. We and others previously described a second hMOF-containing HAT complex, the non-specific lethal (NSL) HAT complex. The NSL complex has a broader substrate specificity, can acetylate H4 on K16, K5, and K8. The WD (tryptophan-aspartate) repeat domain 5 (WDR5) and host cell factor 1 (HCF1) are shared among members of the MLL/SET (mixed-lineage leukemia/set-domain containing) family of histone H3K4 methyltransferase complexes. The presence of these shared subunits raises the possibility that there are functional links between these complexes and the histone modifications they catalyze; however, the degree to which NSL and MLL/SET influence one another's activities remains unclear. Here, we present evidence from biochemical assays and knockdown/overexpression approaches arguing that the NSL HAT promotes histone H3K4me2 by MLL/SET complexes by an acetylation-dependent mechanism. In genomic experiments, we identified a set of genes including ANKRD2, that are affected by knockdown of both NSL and MLL/SET subunits, suggested they are co-regulated by NSL and MLL/SET complexes. In ChIP assays, we observe that depletion of the NSL subunits hMOF or NSL1 resulted in a significant reduction of both H4K16ac and H3K4me2 in the vicinity of the ANKRD2 transcriptional start site proximal region. However, depletion of RbBP5 (a core component of MLL/SET complexes) only reduced H3K4me2 marks, but not H4K16ac in the same region of ANKRD2, consistent with the idea that NSL acts upstream of MLL/SET to regulate H3K4me2 at certain promoters, suggesting coordination between NSL and MLL/SET complexes is involved in transcriptional regulation of certain genes. Taken together, our results suggest a crosstalk between the NSL and MLL/SET complexes in cells.

Evidence of a MOF histone acetyltransferase-containing NSL complex inC. elegans

“…41 The DPY-30 protein is homologous to human protein hDPY-30, which is a member of the COMPASS complex. 42 In light of the reported co-ordination of NSL and COMPASS complex activity in humans noted above, 26 it is of interest that we also demonstrated a direct interaction between DPY-30 and both SUMV-1 and SUMV-2 using yeast two-hybrid assays. 34 The common phenotype of synMuv suppression, combined with evidence of physical association, suggests that DPY-30 might facilitate a functional interaction between the nematode COMPASS complex and putative NSL complex.…”

“…23 Interestingly, coordinated activity of the NSL and COMPASS complexes has been proposed, with WDR5 acting as a bridge between the two. 26 Recently, however, it has been reported that the interaction of WDR5 with NSL complex components occurs via the same regions with which WDR5 interfaces with COMPASS complex components, suggesting that the two interactions are mutually exclusive.…”

MOF Acetylates the Histone Demethylase LSD1 to Suppress Epithelial-to-Mesenchymal Transition

“…Our study shows that MOF blocks H3K4 demethylation by LSD1. Moreover, the NSL complex shares common subunits with the MLL H3K4 methyltransferase complexes (Cai et al, 2010;Dias et al, 2014;Dou et al, 2005;Li et al, 2009;Mendjan et al, 2006;Sharma et al, 2010;Zhao et al, 2013b). Therefore, in addition to implementing H4K16 acetylation, MOF may promote H3K4 methylation by dissociating the LSD1 demethylase and engaging the MLL methyltransferase, thereby driving the transition from a transcription-repressed state to an active state.…”

Structural analysis of the KANSL1/WDR5/KANSL2 complex reveals that WDR5 is required for efficient assembly and chromatin targeting of the NSL complex

“…However, while the structure of the WDR5 b-propeller domain and its ability to bind H3, the WIN motif, and RbBP5 within MLL complexes are well documented, it remains unclear how WDR5 presents itself within other complexes, such as NSL or ATAC. WDR5 was proposed to be a bridging or crossshared subunit between the NSL and MLL/COMPASS complexes, forming complexes with both histone methyltransferase and acetyltransferase activities (Dou et al 2005;Li et al 2009;Zhao et al 2013b). However, we and others could not confirm the existence of such a complex (Cai et al 2010;Raja et al 2010).…”