Chromatin remodeling of histone H3 variants by DDM1 underlies epigenetic inheritance of DNA methylation.

Nucleosomes block access to DNA methyltransferase, unless they are remodeled by DECREASE in DNA METHYLATION 1 (DDM1LSH/HELLS), a Snf2-like master regulator of epigenetic inheritance. We show that DDM1 promotes replacement of histone variant H3.3 by H3.1. In ddm1 mutants, DNA methylation is partly restored by loss of the H3.3 chaperone HIRA, while the H3.1 chaperone CAF-1 becomes essential. The single-particle cryo-EM structure at 3.2 Å of DDM1 with a variant nucleosome reveals engagement with histone H3.3 near residues required for assembly and with the unmodified H4 tail. An N-terminal autoinhibitory domain inhibits activity, while a disulfide bond in the helicase domain supports activity. DDM1 co-localizes with H3.1 and H3.3 during the cell cycle, and with the DNA methyltransferase MET1Dnmt1, but is blocked by H4K16 acetylation. The male germline H3.3 variant MGH3/HTR10 is resistant to remodeling by DDM1 and acts as a placeholder nucleosome in sperm cells for epigenetic inheritance.

Heterochromatic 3D genome organization is directed by HP1a- and H3K9-dependent and independent mechanisms.

Whether and how histone post-translational modifications and the proteins that bind them drive 3D genome organization remains unanswered. Here, we evaluate the contribution of H3K9-methylated constitutive heterochromatin to 3D genome organization in Drosophila tissues. We find that the predominant organizational feature of wild-type tissues is the segregation of euchromatic chromosome arms from heterochromatic pericentromeres. Reciprocal perturbation of HP1a⋅H3K9me binding, using a point mutation in the HP1a chromodomain or replacement of the replication-dependent histone H3 with H3K9R mutant histones, revealed that HP1a binding to methylated H3K9 in constitutive heterochromatin is required to limit contact frequency between pericentromeres and chromosome arms and regulate the distance between arm and pericentromeric regions. Surprisingly, the self-association of pericentromeric regions is largely preserved despite the loss of H3K9 methylation and HP1a occupancy. Thus, the HP1a⋅H3K9 interaction contributes to but does not solely drive the segregation of euchromatin and heterochromatin inside the nucleus.

Histone phosphorylation integrates the hepatic glucagon-PKA-CREB gluconeogenesis program in response to fasting.

The glucagon-PKA signal is generally believed to control hepatic gluconeogenesis via the CREB transcription factor. Here we uncovered a distinct function of this signal in directly stimulating histone phosphorylation for gluconeogenic gene regulation in mice. In the fasting state, CREB recruited activated PKA to regions near gluconeogenic genes, where PKA phosphorylated histone H3 serine 28 (H3S28ph). H3S28ph, recognized by 14-3-3ζ, promoted recruitment of RNA polymerase II and transcriptional stimulation of gluconeogenic genes. In contrast, in the fed state, more PP2A was found near gluconeogenic genes, which counteracted PKA by dephosphorylating H3S28ph and repressing transcription. Importantly, ectopic expression of phosphomimic H3S28 efficiently restored gluconeogenic gene expression when liver PKA or CREB was depleted. These results together highlight a different functional scheme in regulating gluconeogenesis by the glucagon-PKA-CREB-H3S28ph cascade, in which the hormone signal is transmitted to chromatin for rapid and efficient gluconeogenic gene activation.

Molecular basis for PHF7-mediated ubiquitination of histone H3.

The RING-type E3 ligase has been known for over two decades, yet its diverse modes of action are still the subject of active research. Plant homeodomain (PHD) finger protein 7 (PHF7) is a RING-type E3 ubiquitin ligase responsible for histone ubiquitination. PHF7 comprises three zinc finger domains: an extended PHD (ePHD), a RING domain, and a PHD. While the function of the RING domain is largely understood, the roles of the other two domains in E3 ligase activity remain elusive. Here, we present the crystal structure of PHF7 in complex with the E2 ubiquitin-conjugating enzyme (E2). Our structure shows that E2 is effectively captured between the RING domain and the C-terminal PHD, facilitating E2 recruitment through direct contact. In addition, through in vitro binding and functional assays, we demonstrate that the N-terminal ePHD recognizes the nucleosome via DNA binding, whereas the C-terminal PHD is involved in histone H3 recognition. Our results provide a molecular basis for the E3 ligase activity of PHF7 and uncover the specific yet collaborative contributions of each domain to the PHF7 ubiquitination activity.

HIRA-dependent boundaries between H3 variants shape early replication in mammals.

The lack of a consensus DNA sequence defining replication origins in mammals has led researchers to consider chromatin as a means to specify these regions. However, to date, there is no mechanistic understanding of how this could be achieved and maintained given that nucleosome disruption occurs with each fork passage and with transcription. Here, by genome-wide mapping of the de novo deposition of the histone variants H3.1 and H3.3 in human cells during S phase, we identified how their dual deposition mode ensures a stable marking with H3.3 flanked on both sides by H3.1. These H3.1/H3.3 boundaries correspond to the initiation zones of early origins. Loss of the H3.3 chaperone HIRA leads to the concomitant disruption of H3.1/H3.3 boundaries and initiation zones. We propose that the HIRA-dependent deposition of H3.3 preserves H3.1/H3.3 boundaries by protecting them from H3.1 invasion linked to fork progression, contributing to a chromatin-based definition of early replication zones.

A massive alteration of gene expression in undescended testicles of dogs and the association of KAT6A variants with cryptorchidism.

Cryptorchidism is the most common form of disorder of sex development in male dogs, but its hereditary predisposition is poorly elucidated. The gonadal transcriptome of nine unilaterally cryptorchid dogs and seven control dogs was analyzed using RNA-seq. Comparison between the scrotal and inguinal gonads of unilateral cryptorchid dogs revealed 8,028 differentially expressed genes (DEGs) (3,377 up-regulated and 4,651 down-regulated). A similar number of DEGs (7,619) was found by comparing the undescended testicles with the descended testicles of the control dogs. The methylation status of the selected DEGs was also analyzed, with three out of nine studied DEGs showing altered patterns. Bioinformatic analysis of the cDNA sequences revealed 20,366 SNP variants, six of which showed significant differences in allelic counts between cryptorchid and control dogs. Validation studies in larger cohorts of cryptorchid (n = 122) and control (n = 173) dogs showed that the TT genotype (rs850666472, p.Ala1230Val) and the AA genotype in 3'UTR (16:23716202G>A) in KATA6, responsible for acetylation of lysine 9 in histone H3, are associated with cryptorchidism (P = 0.0383). Both the transcript level of KAT6A and H3K9 acetylation were lower in undescended testes, and additionally, the acetylation depended on the genotypes in exon 17 and the 3'UTR. Our study showed that the massive alteration of the transcriptome in undescended testicles is not caused by germinal DNA variants in DEG regulatory sequences but is partly associated with an aberrant DNA methylation and H3K9 acetylation patterns. Moreover, variants of KAT6A can be considered markers associated with the risk of this disorder.

Synergistic lethality between BRCA1 and H3K9me2 loss reflects satellite derepression.

Caenorhabditis elegans has two histone H3 Lys9 methyltransferases, MET-2 (SETDB1 homolog) and SET-25 (G9a/SUV39H1 related). In worms, we found simple repeat sequences primarily marked by H3K9me2, while transposable elements and silent tissue-specific genes bear H3K9me3. RNA sequencing (RNA-seq) in histone methyltransferase (HMT) mutants shows that MET-2-mediated H3K9me2 is necessary for satellite repeat repression, while SET-25 silences a subset of transposable elements and tissue-specific genes through H3K9me3. A genome-wide synthetic lethality screen showed that RNA processing, nuclear RNA degradation, the BRCA1/BARD1 complex, and factors mediating replication stress survival are necessary for germline viability in worms lacking MET-2 but not SET-25. Unlike set-25 mutants, met-2-null worms accumulated satellite repeat transcripts, which form RNA:DNA hybrids on repetitive sequences, additively with the loss of BRCA1 or BARD1. BRCA1/BARD1-mediated H2A ubiquitination and MET-2 deposited H3K9me2 on satellite repeats are partially interdependent, suggesting both that the loss of silencing generates BRCA-recruiting DNA damage and that BRCA1 recruitment by damage helps silence repeats. The artificial induction of MSAT1 transcripts can itself trigger damage-induced germline lethality in a wild-type background, arguing that the synthetic sterility upon BRCA1/BARD1 and H3K9me2 loss is directly linked to the DNA damage provoked by unscheduled satellite repeat transcription.

Warm temperature-triggered developmental reprogramming requires VIL1-mediated, genome-wide H3K27me3 accumulation in Arabidopsis.

Changes in ambient temperature immensely affect developmental programs in many species. Plants adapt to high ambient growth temperature in part by vegetative and reproductive developmental reprogramming, known as thermo-morphogenesis. Thermo-morphogenesis is accompanied by massive changes in the transcriptome upon temperature change. Here, we show that transcriptome changes induced by warm ambient temperature require VERNALIZATION INSENSITIVE 3-LIKE 1 (VIL1), a facultative component of the Polycomb repressive complex PRC2, in Arabidopsis. Warm growth temperature elicits genome-wide accumulation of H3K27me3 and VIL1 is necessary for the warm temperature-mediated accumulation of H3K27me3. Consistent with its role as a mediator of thermo-morphogenesis, loss of function of VIL1 results in hypo-responsiveness to warm ambient temperature. Our results show that VIL1 is a major chromatin regulator in responses to high ambient temperature.

Histone lysine demethylase KDM5B facilitates proliferation and suppresses apoptosis in human acute myeloid leukemia cells through the miR-140-3p/BCL2 axis.

The histone lysine demethylase KDM5B is frequently up-regulated in various human cancer cells. However, its expression and functional role in human acute myeloid leukemia (AML) cells remain unclear. Here, we found that the expression level of KDM5B is high in primary human AML cells. We have demonstrated that knocking down KDM5B leads to apoptosis and impairs proliferation in primary human AML and some human AML cell lines. We further identified miR-140-3p as a downstream target gene of KDM5B. KDM5B expression was inversely correlated with the miR-140-3p level in primary human AML cells. Molecular studies showed that silencing KDM5B enhanced H3K4 trimethylation (H3K4me3) at the promoter of miR-140-3p, leading to high expression of miR-140-3p, which in turn inhibited B-cell CLL/lymphoma 2 (BCL2) expression. Finally, we demonstrate that the defective proliferation induced by KDM5B knockdown (KD) can be rescued with the miR-140-3p inhibitor or enhanced by combining KDM5B KD with a BCL2 inhibitor. Altogether, our data support the conclusion that KDM5B promotes tumorigenesis in human AML cells through the miR-140-3p/BCL2 axis. Targeting the KDM5B/miR-140-3p/BCL2 pathway may hold therapeutic promise for treating human AML.

A Bifunctional Role for the UHRF1 UBL Domain in the Control of Hemi-methylated DNA-Dependent Histone Ubiquitylation.

DNA methylation patterns regulate gene expression programs and are maintained through a highly coordinated process orchestrated by the RING E3 ubiquitin ligase UHRF1. UHRF1 controls DNA methylation inheritance by reading epigenetic modifications to histones and DNA to activate histone H3 ubiquitylation. Here, we find that all five domains of UHRF1, including the previously uncharacterized ubiquitin-like domain (UBL), cooperate for hemi-methylated DNA-dependent H3 ubiquitin ligation. Our structural and biochemical studies, including mutations found in cancer genomes, reveal a bifunctional requirement for the UBL in histone modification: (1) the UBL makes an essential interaction with the backside of the E2 and (2) the UBL coordinates with other UHRF1 domains that recognize epigenetic marks on DNA and histone H3 to direct ubiquitin to H3. Finally, we show UBLs from other E3s also have a conserved interaction with the E2, Ube2D, highlighting a potential prevalence of interactions between UBLs and E2s.

HIRA complex deposition of histone H3.3 is driven by histone tetramerization and histone-DNA binding.

The HIRA histone chaperone complex is comprised of four protein subunits: HIRA, UBN1, CABIN1, and transiently associated ASF1a. All four subunits have been demonstrated to play a role in the deposition of the histone variant H3.3 onto areas of actively transcribed euchromatin in cells. The mechanism by which these subunits function together to drive histone deposition has remained poorly understood. Here we present biochemical and biophysical data supporting a model whereby ASF1a delivers histone H3.3/H4 dimers to the HIRA complex, H3.3/H4 tetramerization drives the association of two HIRA/UBN1 complexes, and the affinity of the histones for DNA drives release of ASF1a and subsequent histone deposition. These findings have implications for understanding how other histone chaperone complexes may mediate histone deposition.

The H3.3 chaperone Hira complex orchestrates oocyte developmental competence.

Successful reproduction requires an oocyte competent to sustain early embryo development. By the end of oogenesis, the oocyte has entered a transcriptionally silenced state, the mechanisms and significance of which remain poorly understood. Histone H3.3, a histone H3 variant, has unique cell cycle-independent functions in chromatin structure and gene expression. Here, we have characterised the H3.3 chaperone Hira/Cabin1/Ubn1 complex, showing that loss of function of any of these subunits causes early embryogenesis failure in mouse. Transcriptome and nascent RNA analyses revealed that transcription is aberrantly silenced in mutant oocytes. Histone marks, including H3K4me3 and H3K9me3, are reduced and chromatin accessibility is impaired in Hira/Cabin1 mutants. Misregulated genes in mutant oocytes include Zscan4d, a two-cell specific gene involved in zygote genome activation. Overexpression of Zscan4 in the oocyte partially recapitulates the phenotypes of Hira mutants and Zscan4 knockdown in Cabin1 mutant oocytes partially restored their developmental potential, illustrating that temporal and spatial expression of Zscan4 is fine-tuned at the oocyte-to-embryo transition. Thus, the H3.3 chaperone Hira complex has a maternal effect function in oocyte developmental competence and embryogenesis, through modulating chromatin condensation and transcriptional quiescence.

Histone H3.3 chaperone HIRA renders stress-responsive genes poised for prospective lethal stresses in acquired tolerance.

Appropriate responses to environmental challenges are imperative for the survival of all living organisms. Exposure to low-dose stresses is recognized to yield increased cellular fitness, a phenomenon termed hormesis. However, our molecular understanding of how cells respond to low-dose stress remains profoundly limited. Here we report that histone variant H3.3-specific chaperone, HIRA, is required for acquired tolerance, where low-dose heat stress exposure confers resistance to subsequent lethal heat stress. We found that human HIRA activates stress-responsive genes, including HSP70, by depositing histone H3.3 following low-dose stresses. These genes are also marked with histone H3 Lys-4 trimethylation and H3 Lys-9 acetylation, both active chromatin markers. Moreover, depletion of HIRA greatly diminished acquired tolerance, both in normal diploid fibroblasts and in HeLa cells. Collectively, our study revealed that HIRA is required for eliciting adaptive stress responses under environmental fluctuations and is a master regulator of stress tolerance.

Determinants of Histone H3K4 Methylation Patterns.

Various factors differentially recognize trimethylated histone H3 lysine 4 (H3K4me3) near promoters, H3K4me2 just downstream, and promoter-distal H3K4me1 to modulate gene expression. This methylation "gradient" is thought to result from preferential binding of the H3K4 methyltransferase Set1/complex associated with Set1 (COMPASS) to promoter-proximal RNA polymerase II. However, other studies have suggested that location-specific cues allosterically activate Set1. Chromatin immunoprecipitation sequencing (ChIP-seq) experiments show that H3K4 methylation patterns on active genes are not universal or fixed and change in response to both transcription elongation rate and frequency as well as reduced COMPASS activity. Fusing Set1 to RNA polymerase II results in H3K4me2 throughout transcribed regions and similarly extended H3K4me3 on highly transcribed genes. Tethered Set1 still requires histone H2B ubiquitylation for activity. These results show that higher-level methylations reflect not only Set1/COMPASS recruitment but also multiple rounds of transcription. This model provides a simple explanation for non-canonical methylation patterns at some loci or in certain COMPASS mutants.

Inhibition of EHMT1/2 rescues synaptic damage and motor impairment in a PD mouse model.

Epigenetic dysregulation that leads to alterations in gene expression and is suggested to be one of the key pathophysiological factors of Parkinson's disease (PD). Here, we found that α-synuclein preformed fibrils (PFFs) induced histone H3 dimethylation at lysine 9 (H3K9me2) and increased the euchromatic histone methyltransferases EHMT1 and EHMT2, which were accompanied by neuronal synaptic damage, including loss of synapses and diminished expression levels of synaptic-related proteins. Furthermore, the levels of H3K9me2 at promoters in genes that encode the synaptic-related proteins SNAP25, PSD95, Synapsin 1 and vGLUT1 were increased in primary neurons after PFF treatment, which suggests a linkage between H3K9 dimethylation and synaptic dysfunction. Inhibition of EHMT1/2 with the specific inhibitor A-366 or shRNA suppressed histone methylation and alleviated synaptic damage in primary neurons that were treated with PFFs. In addition, the synaptic damage and motor impairment in mice that were injected with PFFs were repressed by treatment with the EHMT1/2 inhibitor A-366. Thus, our findings reveal the role of histone H3 modification by EHMT1/2 in synaptic damage and motor impairment in a PFF animal model, suggesting the involvement of epigenetic dysregulation in PD pathogenesis.

ALKHB5-demethylated lncRNA SNHG15 promotes myeloma tumorigenicity by increasing chromatin accessibility and recruiting H3K36me3 modifier SETD2.

Chromatin instability plays a crucial role in multiple myeloma (MM) relapse and progression, but its mechanism remains obscure. Here, we uncovered that m6A-demethylase ALKBH5 upregulated and stabilized long noncoding RNA (lncRNA) small nucleolar RNA host gene 15 (SNHG15), which was elevated in MM and positively correlated with unfavorable clinical prognosis factors. ALKBH5-SNHG15 axis participated in viability and migration/invasion of myeloma cell lines and MM-xenografted SCID/NOD mice. Mechanically, ALKBH5 promoted the expression of trimethylated histone H3 at lysine 36 (H3K36me3) methyltransferase SETD2 through lncRNA SNHG15-mediated protein stability. ALKBH5-SNHG15 axis increased chromatin accessibility and altered the H3K36me3 enrichment at the gene body, which is responsible for transcription elongation. Our study suggested a novel epigenetically interaction of N6-methyladenosine (m6A) methylation, lncRNA SNHG15, and histone SETD2/H3K36me3 modifications in myeloma progression, indicating that ALKBH5 and lncRNA SNHG15 could serve as potential novel therapeutic targets for MM treatment.NEW & NOTEWORTHY To our knowledge, this study first demonstrated the prognostic significance and biological function of long noncoding RNA (lncRNA) small nucleolar RNA host gene 15 (SNHG15) in multiple myeloma (MM), and indicated a novel revelation on the effect of N6-methyladenosine (m6A)-regulated lncRNA on MM tumorigenicity. Moreover, the novel chromatin-regulatory mechanism of lncRNA by interacting with epigenetic modifiers including m6A demethylase ALKBH5 and H3K36me3 methyltransferase SETD2 in myeloma progression elucidated intricate mechanism of tumor pathogenesis.

Quantitative Pattern of hPTMs by Mass Spectrometry-Based Proteomics with Implications for Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is known for its aggressive nature, and TNBC management is currently challenging due to the lack of effective targets. Despite the importance of histone post-translational modifications (hPTMs) in breast cancer, their associations with molecular subtypes of breast cancer, especially TNBC, are poorly understood. In this study, a combination of untargeted and targeted proteomics approaches, supplemented by a derivatization method, was applied to breast cancer cells and tissue samples. Untargeted proteomics of eight breast cancer cell lines belonging to different molecular subtypes revealed 36 modified peptides with 12 lysine modification sites in histone H3, and the most frequently reported top 5 histone H3 methylation and acetylation sites were covered. Then, targeted proteomics was carried out to quantify the total 20 target hPTMs at the covered modification sites (i.e., mono-, di-, trimethylation, and acetylation for each site), indicating the difficulty in distinguishing TNBC cells from normal cells. Subsequently, the analysis in TNBC patients revealed significant expression differences in 4 specific hPTMs (H3K14ac, H3K27me1, H3K36me2, and H3K36me3) between TNBC and adjacent normal tissue samples. These unique hPTM patterns allowed for the differentiation of TNBC from normal cases. This finding provides promising implications for advancing targeted treatment strategies for TNBC in the future.

A complete methyl-lysine binding aromatic cage constructed by two domains of PHF2.

The N-terminal half of PHF2 harbors both a plant homeodomain (PHD) and a Jumonji domain. The PHD recognizes both histone H3 trimethylated at lysine 4 and methylated nonhistone proteins including vaccinia-related kinase 1 (VRK1). The Jumonji domain erases the repressive dimethylation mark from histone H3 lysine 9 (H3K9me2) at select promoters. The N-terminal amino acid sequences of H3 (AR2TK4) and VRK1 (PR2VK4) bear an arginine at position 2 and lysine at position 4. Here, we show that the PHF2 N-terminal half binds to H3 and VRK1 peptides containing K4me3, with dissociation constants (KD values) of 160 nM and 42 nM, respectively, which are 4 × and 21 × lower (and higher affinities) than for the isolated PHD domain of PHF2. X-ray crystallography revealed that the K4me3-containing peptide is positioned within the PHD and Jumonji interface, with the positively charged R2 residue engaging acidic residues of the PHD and Jumonji domains and with the K4me3 moiety encircled by aromatic residues from both domains. We suggest that the micromolar binding affinities commonly observed for isolated methyl-lysine reader domains could be improved via additional functional interactions within the same polypeptide or its binding partners.

Balanced spatiotemporal arrangements of histone H3 and H4 posttranslational modifications are necessary for meiotic prophase I chromosome organization.

Dynamic nuclear architecture and chromatin organizations are the key features of the mid-prophase I in mammalian meiosis. The chromatin undergoes major changes, including meiosis-specific spatiotemporal arrangements and remodeling, the establishment of chromatin loop-axis structure, pairing, and crossing over between homologous chromosomes, any deficiencies in these events may induce genome instability, subsequently leading to failure to produce gametes and infertility. Despite the significance of chromatin structure, little is known about the location of chromatin marks and the necessity of their balance during meiosis prophase I. Here, we show a thorough cytological study of the surface-spread meiotic chromosomes of mouse spermatocytes for H3K9,14,18,23,27,36, H4K12,16 acetylation, and H3K4,9,27,36 methylation. Active acetylation and methylation marks on H3 and H4, such as H3K9ac, H3K14ac, H3K18ac, H3K36ac, H3K56ac, H4K12ac, H4K16ac, and H3K36me3 exhibited pan-nuclear localization away from heterochromatin. In comparison, repressive marks like H3K9me3 and H3K27me3 are localized to heterochromatin. Further, taking advantage of the delivery of small-molecule chemical inhibitors methotrexate (heterochromatin enhancer), heterochromatin inhibitor, anacardic acid (histone acetyltransferase inhibitor), trichostatin A (histone deacetylase inhibitor), IOX1 (JmjC demethylases inhibitor), and AZ505 (methyltransferase inhibitor) in seminiferous tubules through the rete testis route, revealed that alteration in histone modifications enhanced the centromere mislocalization, chromosome breakage, altered meiotic recombination and reduced sperm count. Specifically, IOX1 and AZ505 treatment shows severe meiotic phenotypes, including altering chromosome axis length and chromatin loop size via transcriptional regulation of meiosis-specific genes. Our findings highlight the importance of balanced chromatin modifications in meiotic prophase I chromosome organization and instability.

The Chaperone NASP Contributes to de Novo Deposition of the Centromeric Histone Variant CENH3 in Arabidopsis Early Embryogenesis.

The centromere is an essential chromosome region where the kinetochore is formed to control equal chromosome distribution during cell division. The centromere-specific histone H3 variant CENH3 (also called CENP-A) is a prerequisite for the kinetochore formation. Since CENH3 evolves rapidly, associated factors, including histone chaperones mediating the deposition of CENH3 on the centromere, are thought to act through species-specific amino acid sequences. The functions and interaction networks of CENH3 and histone chaperons have been well-characterized in animals and yeasts. However, molecular mechanisms involved in recognition and deposition of CENH3 are still unclear in plants. Here, we used a swapping strategy between domains of CENH3 of Arabidopsis thaliana and the liverwort Marchantia polymorpha to identify specific regions of CENH3 involved in targeting the centromeres and interacting with the general histone H3 chaperone, nuclear autoantigenic sperm protein (NASP). CENH3's LoopN-α1 region was necessary and sufficient for the centromere targeting in cooperation with the α2 region and was involved in interaction with NASP in cooperation with αN, suggesting a species-specific CENH3 recognition. In addition, by generating an Arabidopsis nasp knock-out mutant in the background of a fully fertile GFP-CENH3/cenh3-1 line, we found that NASP was implicated for de novo CENH3 deposition after fertilization and thus for early embryo development. Our results imply that the NASP mediates the supply of CENH3 in the context of the rapidly evolving centromere identity in land plants.