The phosphorylation of the serine 10 at histone H3 has been shown to be important for transcriptional activation. Here, we report the molecular mechanism through which H3S10ph triggers transcript elongation of the FOSL1 gene. Serum stimulation induces the PIM1 kinase to phosphorylate the preacetylated histone H3 at the FOSL1 enhancer. The adaptor protein 14-3-3 binds the phosphorylated nucleosome and recruits the histone acetyltransferase MOF, which triggers the acetylation of histone H4 at lysine 16 (H4K16ac). This histone crosstalk generates the nucleosomal recognition code composed of H3K9acS10ph/H4K16ac determining a nucleosome platform for the bromodomain protein BRD4 binding. The recruitment of the positive transcription elongation factor b (P-TEFb) via BRD4 induces the release of the promoter-proximal paused RNA polymerase II and the increase of its processivity. Thus, the single phosphorylation H3S10ph at the FOSL1 enhancer triggers a cascade of events which activate transcriptional elongation.

RSK2 kinases [4][5][6][7] . In response to inflammatory cytokines, IKK-α phosphorylates H3S10 at NFkB-responsive promoters 8,9 .In this study, we analyzed the function of PIM1, a constitutively active serine/threonine kinase. To understand the function of PIM1, we investigated the molecular connection between PIM1and MYC. We propose that the recruitment of PIM1 to the chromatin by MYC contributes to transcriptional activation of MYC-target genes by phosphorylating H3S10 at the E box element and suggest that this cooperation is relevant for MYC-dependent tumour formation. RESULTS PIM1 phosphorylates the nucleosome at H3S10.PIM1 mRNA is induced with fast kinetics in HUVEC treated with VEGF-A 11 . Upon VEGF-A treatment PIM1 is induced and localizes in HUVEC nuclei within 40 minutes (see Supplementary Information Fig. S1). As PIM1 is a serine/threonine kinase with putative consensus sites present on histones, its nuclear localization could account for the increase of H3 phosphorylation observed in these cells between 60 and 90 minutes after VEGF-A treatment (see Supplementary Information Fig. S1). We found that PIM1 could directly phosphorylate nucleosomes in vitro by incubating the recombinant GST-PIM1 protein with chromatin fractions obtained from 293 cells in the presence of [γ 32 P] ATP. This analysis revealed that a single protein, with molecular weight corresponding to H3, was phosphorylated by wild type GST-PIM1, but not by the kinase inactive mutant GST-PIM1-K67M (Fig. 1a, lanes 1-3). Specific inhibition of nucleosome phosphorylation was observed in the presence of a peptide derived from the H3 N-terminus but not with a peptide derived from H2B Nterminus or with an unrelated peptide (Fig. 1a, lanes 4-12). PIM1 could phosphorylate PIM1 forms a complex with MYC and MAX.VEGF-A treatment induces MYC and PIM1 co-localization in the cell nuclei at 60 minutes, decreasing thereafter (Fig. 2a). We tested whether PIM1 coimmunoprecipitaes with MYC.Time course analysis in HUVEC treated with VEGF-A showed that upon induction, both MYC and PIM1 were induced with fast kinetics. Immunoprecipitations with anti-MAX antibodies at various time points showed the formation of the MAX/MYC complex from 60 minutes after growth factor stimulation thus corresponding to the appearance of MYC in the nucleus (Fig. 2b, right panel). Importantly, PIM1 co-immunoprecipitated with MYC and MAX suggesting that a complex containing PIM1 is formed. Endogenous PIM1 was also found to co-immunoprecipitate with endogenous MYC and MAX from 293 cells after serum treatment for 120 minutes (Fig. 2c), thus demonstrating that a MAX/MYC/PIM1 endogenous complex is also formed in these cells.As MYC-dependent cell transformation requires MYC boxII (MBII) domain to bind cofactors either in a TRRAP-dependent or -independent manner 24 , we tested whether PIM1 interacts (Fig. 2d). Endogenous TRRAP associated with MYC but not with the FLAG-MYC MBII as previously described 25 . In contrast, PIM1did not co-immunoprecipitate the endogenous TRRAP (lanes 5 and 10) ...

Highlights d Loss of SETD5 impairs brain development and neuronal functions d Setd5 mutant mice exhibit cognitive and sociobehavioral deficits d SETD5 loss leads to an unfavorable chromatin state for RNA elongation and splicing d SETD5 has intrinsic histone methyltransferase activity for H3K36

Reduction of lamin A/C, which is evolutionarily required for the modulation of Polycomb group (PcG) protein–dependent transcriptional repression by sustaining PcG protein nuclear architecture, leads to PcG protein diffusion and to muscle differentiation.