Ribosome 18S m6A Methyltransferase METTL5 Promotes Translation Initiation and Breast Cancer Cell Growth.

N6 methylation at adenosine 1832 (m6A1832) of mammalian 18S rRNA, occupying a critical position within the decoding center, is modified by a conserved methyltransferase, METTL5. Here, we find that METTL5 shows strong substrate preference toward the 18S A1832 motif but not the other reported m6A motifs. Comparison with a yeast ribosome structural model unmodified at this site indicates that the modification may facilitate mRNA binding by inducing conformation changes in the mammalian ribosomal decoding center. METTL5 promotes p70-S6K activation and proper translation initiation, and the loss of METTL5 significantly reduces the abundance of polysome. METTL5 expression is elevated in breast cancer patient samples and is required for growth of several breast cancer cell lines. We further find that Caenorhabditis elegans lacking the homolog metl-5 develop phenotypes known to be associated with impaired translation. Altogether, our findings uncover critical and conserved roles of METTL5 in the regulation of translation.

SETD2 deficiency accelerates MDS-associated leukemogenesis via S100a9 in NHD13 mice and predicts poor prognosis in MDS.

SETD2, the histone H3 lysine 36 methyltransferase, previously identified by us, plays an important role in the pathogenesis of hematologic malignancies, but its role in myelodysplastic syndromes (MDSs) has been unclear. In this study, low expression of SETD2 correlated with shortened survival in patients with MDS, and the SETD2 levels in CD34+ bone marrow cells of those patients were increased by decitabine. We knocked out Setd2 in NUP98-HOXD13 (NHD13) transgenic mice, which phenocopies human MDS, and found that loss of Setd2 accelerated the transformation of MDS into acute myeloid leukemia (AML). Loss of Setd2 enhanced the ability of NHD13+ hematopoietic stem and progenitor cells (HSPCs) to self-renew, with increased symmetric self-renewal division and decreased differentiation and cell death. The growth of MDS-associated leukemia cells was inhibited though increasing the H3K36me3 level by using epigenetic modifying drugs. Furthermore, Setd2 deficiency upregulated hematopoietic stem cell signaling and downregulated myeloid differentiation pathways in the NHD13+ HSPCs. Our RNA-seq and chromatin immunoprecipitation-seq analysis indicated that S100a9, the S100 calcium-binding protein, is a target gene of Setd2 and that the addition of recombinant S100a9 weakens the effect of Setd2 deficiency in the NHD13+ HSPCs. In contrast, downregulation of S100a9 leads to decreases of its downstream targets, including Ikba and Jnk, which influence the self-renewal and differentiation of HSPCs. Therefore, our results demonstrated that SETD2 deficiency predicts poor prognosis in MDS and promotes the transformation of MDS into AML, which provides a potential therapeutic target for MDS-associated acute leukemia.

Refined spatial temporal epigenomic profiling reveals intrinsic connection between PRDM9-mediated H3K4me3 and the fate of double-stranded breaks.

Meiotic recombination is initiated by the formation of double-strand breaks (DSBs), which are repaired as either crossovers (COs) or noncrossovers (NCOs). In most mammals, PRDM9-mediated H3K4me3 controls the nonrandom distribution of DSBs; however, both the timing and mechanism of DSB fate control remain largely undetermined. Here, we generated comprehensive epigenomic profiles of synchronized mouse spermatogenic cells during meiotic prophase I, revealing spatiotemporal and functional relationships between epigenetic factors and meiotic recombination. We find that PRDM9-mediated H3K4me3 at DSB hotspots, coinciding with H3K27ac and H3K36me3, is intimately connected with the fate of the DSB. Our data suggest that the fate decision is likely made at the time of DSB formation: earlier formed DSBs occupy more open chromatins and are much more competent to proceed to a CO fate. Our work highlights an intrinsic connection between PRDM9-mediated H3K4me3 and the fate decision of DSBs, and provides new insight into the control of CO homeostasis.

Correction to: DNMT3A reads and connects histone H3K36me2 to DNA methylation.

The author would like to add the below information in this correction. A similar study from Chao Lu group was published online on 5 September 2019 in Nature, entitled "The histone mark H3K36me2 recruits DNMT3A and shapes the intergenic DNA methylation landscape" (Weinberg et al., 2019). Although both the studies reported the preferential recognition of H3K36me2 by DNMT3A PWWP, ours in addition uncovered a stimulation function by such interaction on the activity of DNMT3A. On the disease connections, we used a NSD2 gain-of-function model which led to the discovery of potential therapeutic implication of DNA inhibitors in the related cancers, while the other study only used NSD1 and DNMT3A loss-of-function models.

Author Correction: H3K14me3 genomic distributions and its regulation by KDM4 family demethylases.

We apologize for an error introduced during format conversion in the paper published online on 18 October 2018. The resolution of the MALDI-TOF result in Fig. 1e underwent an unexpected reduction when transformed from Powerpoint format. The corrected Fig. 1e is provided below on the left.