Project description:The human NuA4/TIP60 co-activator complex, a fusion of the yeast SWR1 and NuA4 complexes, both incorporates the histone variant H2A.Z into nucleosomes and acetylates histones H4/H2A/H2A.Z to play crucial roles regulating gene expression and maintaining genome stability. Our cryo-EM studies show that within the NuA4/TIP60 complex, the EP400 subunit serves as an architectural scaffold holding the different functional modules in specific positions and giving rise to a novel arrangement of the ARP module. EP400 interacts with the TRRAP subunit using a footprint that overlaps with that of the SAGA acetyltransferase complex, thereby preventing the formation of a hybrid complex. Loss of the TRRAP subunit leads to mislocalization of NuA4/TIP60, resulting in the redistribution of H2A.Z and its acetylation across the genome, emphasizing the dual functionality of NuA4/TIP60 as a single macromolecular assembly.
Project description:The human NuA4/TIP60 co-activator complex, a fusion of the yeast SWR1 and NuA4 complexes, both incorporates the histone variant H2A.Z into nucleosomes and acetylates histones H4/H2A/H2A.Z to play crucial roles regulating gene expression and maintaining genome stability. Our cryo-EM studies show that within the NuA4/TIP60 complex, the EP400 subunit serves as an architectural scaffold holding the different functional modules in specific positions and giving rise to a novel arrangement of the ARP module. EP400 interacts with the TRRAP subunit using a footprint that overlaps with that of the SAGA acetyltransferase complex, thereby preventing the formation of a hybrid complex. Loss of the TRRAP subunit leads to mislocalization of NuA4/TIP60, resulting in the redistribution of H2A.Z and its acetylation across the genome,emphasizing the dual functionality of NuA4/TIP60 as a single macromolecular assembly.
Project description:The human NuA4/TIP60 co-activator complex, a fusion of the yeast SWR1 and NuA4 complexes, both incorporates the histone variant H2A.Z into nucleosomes and acetylates histones H4/H2A/H2A.Z to play crucial roles regulating gene expression and maintaining genome stability. Our cryo-EM studies show that within the NuA4/TIP60 complex, the EP400 subunit serves as an architectural scaffold holding the different functional modules in specific positions and giving rise to a novel arrangement of the ARP module. EP400 interacts with the TRRAP subunit using a footprint that overlaps with that of the SAGA acetyltransferase complex, thereby preventing the formation of a hybrid complex. Loss of the TRRAP subunit leads to mislocalization of NuA4/TIP60, resulting in the redistribution of H2A.Z and its acetylation across the genome, emphasizing the dual functionality of NuA4/TIP60 as a single macromolecular assembly.
Project description:The human NuA4/TIP60 co-activator complex, a fusion of the yeast SWR1 and NuA4 complexes, both incorporates the histone variant H2A.Z into nucleosomes and acetylates histones H4/H2A/H2A.Z to play crucial roles regulating gene expression and maintaining genome stability. Our cryo-EM studies show that within the NuA4/TIP60 complex, the EP400 subunit serves as an architectural scaffold holding the different functional modules in specific positions and giving rise to a novel arrangement of the ARP module. EP400 interacts with the TRRAP subunit using a footprint that overlaps with that of the SAGA acetyltransferase complex, thereby preventing the formation of a hybrid complex. Loss of the TRRAP subunit leads to mislocalization of NuA4/TIP60, resulting in the redistribution of H2A.Z and its acetylation across the genome, emphasizing the dual functionality of NuA4/TIP60 as a single macromolecular assembly.
Project description:Neuronal activity is critical for adaptive circuit remodeling but poses an inherent risk to the stability of the genome across the long lifespan of post-mitotic neurons1-5. Whether neurons have acquired specialized genome protection mechanisms that enable them to withstand decades of potentially damaging stimuli during periods of heightened activity is not known. Here we identify an activity-dependent DNA repair mechanism via a new form of the NuA4/TIP60 chromatin modifier that assembles in activated neurons around the inducible, neuronal-specific transcription factor NPAS4. We purify this complex directly from the brain and demonstrate its functions in eliciting activity-dependent changes to neuronal transcriptomes and circuitry. By identifying the landscape of activity-induced DNA double-strand breaks in the brain, we show that the NPAS4:NuA4 complex binds to recurrently damaged regulatory elements and recruits additional DNA repair machinery to stimulate their repair. Gene regulatory elements bound by the NPAS4:NuA4 complex are partially protected from age-dependent accumulation of somatic mutations. Impaired NPAS4:NuA4 signaling leads to a cascade of cellular defects including dysregulated transcriptional responses to activity, loss of control over neuronal inhibition, and genome instability, culminating in reduced organismal lifespan. In addition, mutations in several components of the NuA4 complex are reported to lead to neurodevelopmental disorders and autism. Together, these findings identify a neuronal-specific complex that couples neuronal activity directly to genome preservation and whose disruption may contribute to developmental disorders, neurodegeneration and aging.
Project description:A conspicuous feature of early animal development is the lack of transcription from the embryonic genome, and it typically takes several hours to several days (depending on the species) until widespread transcription of the embryonic genome begins. Although this transition is ubiquitous, relatively little is known about how the shift from a transcriptionally quiescent to transcriptionally active genome is controlled. We describe here the genome-wide distributions and temporal dynamics of nucleosomes and post-translational histone modifications through the maternal-to-zygotic transition in embryos of the pomace fly Drosophila melanogaster. At mitotic cycle 8, when few zygotic genes are being transcribed, embryonic chromatin is in a relatively simple state: there are few nucleosome-free regions, undetectable levels of the histone methylation marks characteristic of mature chromatin, and low levels of histone acetylation at a relatively small number of loci. Histone acetylation increases by cycle 12, but it is not until cycle 14 that nucleosome-free regions and domains of histone methylation become widespread. Early histone acetylation is strongly associated with regions that we have previously shown are bound in early embryos by the maternally deposited transcription factor Zelda. Most of these Zelda-bound regions are destined to be enhancers or promoters active during mitotic cycle 14, and our data demonstrate that they are biochemically distinct long before they become active, raising the possibility that Zelda triggers a cascade of events, including the accumulation of specific histone modifications, that plays a role in the subsequent activation of these sequences. Many of these Zelda-associated active regions occur in larger domains that we find strongly enriched for histone marks characteristic of Polycomb-mediated repression, suggesting a dynamic balance between Zelda activation and Polycomb repression. Collectively, these data paint a complex picture of a genome in transition from a quiescent to an active state, and highlight the role of Zelda in mediating this transition. We performed genome-wide mapping of histone H3 and 9 types of histone modifications, including H4K5ac, H4K8ac, H3K4me1, H3K4me3, H3K27me3, H3K36me3, H3K9ac, H3K18ac, and H3K27ac by ChIP-seq, in hand-sorted wild-type Drosophila melanogaster embryos at 4 different development time points corresponding to mitotic cycle 7-9, 11-13, 14a-b, and 14c-d, respectively. We also carried out ChIP-seq experiments in zelda mutant embryos after showing that the deposition of histone marks in early embryos strongly correlated with the binding of Zelda in wild-type embryos.
Project description:In this study, we characterize the fusion protein produced by the ZMYND11-MBTD1 translocation in acute myeloid leukemia. We express the fusion protein and necessary controls in K562 Cells. The fusion protein assembles ZMYND11 factor with the full acetyltransferase NuA4/TIP60 complex. The fusion protein leads to mislocalization NuA4/TIP60 complex in gene bodies, thereby increasing H4ac in specific gene targets. Finally, chromatin aberration is linked to aberrant gene expression and spliced isoforms.
Project description:A recurrent chromosomal translocation detected in cannibalistic acute myeloid leukemia leads to the production of a ZMYND11-MBTD1 fusion protein.
- The ZMYND11-MBTD1 fusion protein is stably incorporated into the endogenous NuA4/TIP60 complex
- ZMYND11-MBTD1 leads to mistargeting of NuA4-TIP60 activity to the coding region of ZMYND11-target genes, altering gene expression and transcript isoforms.
- ZMYND11-MBTD1 binds the MYC gene leading to its upregulation, favoring growth and pluripotency while inhibiting differentiation markers.
Project description:In the germline stem cell lineage, proliferating gonial cells switch from mitotic proliferation to meiotic prophase, marked by the onset of a cell-type-specific transcription program and a specialized cell cycle required to generate haploid gametes. The Drosophila gene benign gonial cell neoplasm (bgcn) encodes an RNA binding translational repressor required in fly testes for spermatogonia to stop dividing and transition to the spermatocyte state and meiosis. Here we show that the mammalian bgcn ortholog, YTHDC2, plays a key role in allowing a clean transition from mitosis to meiosis in both male and female germ cells in mouse, pointing towards a conserved role of post-transcriptional control of RNA translation and/or stability in this critical cell fate transition. Ythdc2-/- male germ cells undergo mitotic divisions but fail to properly execute meiotic prophase, instead attempting a mitotic-like division then undergoing cell death. Many meiotic markers were only weakly expressed in Ythdc2-/- testes compared to wild-type controls. Strikingly, the mitotic cyclin Cyclin A2, which is down-regulated prior to entry into meiotic prophase in wild-type, remained high in Ythdc2-/- germ cells that also expressed the meiotic marker SYCP3, suggesting that the mutant germ cells attempting to enter meiotic prophase have a mixed identity. YTHDC2 binds RNAs involved in both the mitotic cell cycle, including the mRNA Ccna2 that encodes Cyclin A2, as well as specific piRNA precursor RNAs and transcripts required for later stages of germ cell differentiation. YTHDC2-bound RNAs in testes were enriched for the m6A modification, suggesting that YTHDC2 may selectively regulate multiple target RNAs marked with m6A, to promote a clean transition from mitosis to meiosis and terminal differentiation.
Project description:In the germline stem cell lineage, proliferating gonial cells switch from mitotic proliferation to meiotic prophase, marked by the onset of a cell-type-specific transcription program and a specialized cell cycle required to generate haploid gametes. The Drosophila gene benign gonial cell neoplasm (bgcn) encodes an RNA binding translational repressor required in fly testes for spermatogonia to stop dividing and transition to the spermatocyte state and meiosis. Here we show that the mammalian bgcn ortholog, YTHDC2, plays a key role in allowing a clean transition from mitosis to meiosis in both male and female germ cells in mouse, pointing towards a conserved role of post-transcriptional control of RNA translation and/or stability in this critical cell fate transition. Ythdc2-/- male germ cells undergo mitotic divisions but fail to properly execute meiotic prophase, instead attempting a mitotic-like division then undergoing cell death. Many meiotic markers were only weakly expressed in Ythdc2-/- testes compared to wild-type controls. Strikingly, the mitotic cyclin Cyclin A2, which is down-regulated prior to entry into meiotic prophase in wild-type, remained high in Ythdc2-/- germ cells that also expressed the meiotic marker SYCP3, suggesting that the mutant germ cells attempting to enter meiotic prophase have a mixed identity. YTHDC2 binds RNAs involved in both the mitotic cell cycle, including the mRNA Ccna2 that encodes Cyclin A2, as well as specific piRNA precursor RNAs and transcripts required for later stages of germ cell differentiation. YTHDC2-bound RNAs in testes were enriched for the m6A modification, suggesting that YTHDC2 may selectively regulate multiple target RNAs marked with m6A, to promote a clean transition from mitosis to meiosis and terminal differentiation.