Project description:Oct4 is a master regulator of pluripotency. Potential Oct4 interactors have been cataloged extensively but the manner and significance of these interactions are incompletely defined. Like other POU domain proteins, Oct4 is capable of binding to DNA in multiple configurations, however the relationship between these configurations and cofactor recruitment (and hence transcription output) are unknown. Here, we show that Oct4 interacts with common and unique proteins when bound to DNA in different configurations. One of these proteins is Jade1, a component of the HBO histone acetyltransferase complex. Jade1 preferentially associates with Oct4 when bound to More palindromic Octamer-Related Element (MORE) DNA sequences that bind Oct4 dimers and are associated with strong gene expression. We show that the Oct4 N-terminus is critical for this interaction. ChIP-seq using HBO1, the enzymatic component of the complex, identifies a preference for binding adjacent to Oct4 at MORE sites. Using purified recombinant proteins and nucleosome complexes, we show that the HBO1 complex acetylates histone H3K9 within nucleosomes more efficiently when Oct4 is co-bound to a MORE site. Histone acetylation is further increased when Oct4 is mutated to favor dimeric MORE binding. Cryo-electron microscopy reveals that Oct4 bound to a MORE near the nucleosome entry/exit site partially unwinds DNA from nucleosome core particles, and identifies additional mass associated with the HBO1 complex. These results identify a novel mechanism of transcriptional regulation by Oct4.
Project description:Oct4 is a master regulator of pluripotency. Potential Oct4 interactors have been cataloged extensively but the manner and significance of these interactions are incompletely defined. Like other POU domain proteins, Oct4 is capable of binding to DNA in multiple configurations, however the relationship between these configurations and cofactor recruitment (and hence transcription output) are unknown. Here, we show that Oct4 interacts with common and unique proteins when bound to DNA in different configurations. One of these proteins is Jade1, a component of the HBO histone acetyltransferase complex. Jade1 preferentially associates with Oct4 when bound to More palindromic Octamer-Related Element (MORE) DNA sequences that bind Oct4 dimers and are associated with strong gene expression. We show that the Oct4 N-terminus is critical for this interaction. ChIP-seq using HBO1, the enzymatic component of the complex, identifies a preference for binding adjacent to Oct4 at MORE sites. Using purified recombinant proteins and nucleosome complexes, we show that the HBO1 complex acetylates histone H3K9 within nucleosomes more efficiently when Oct4 is co-bound to a MORE site. Histone acetylation is further increased when Oct4 is mutated to favor dimeric MORE binding. Cryo-electron microscopy reveals that Oct4 bound to a MORE near the nucleosome entry/exit site partially unwinds DNA from nucleosome core particles, and identifies additional mass associated with the HBO1 complex. These results identify a novel mechanism of transcriptional regulation by Oct4.
Project description:Lysine benzoylation (Kbz) is a newly discovered protein post-translational modification (PTM). This PTM can be stimulated by benzoate and contributes to gene expression. However, its regulatory enzymes and substrate proteins remain largely unknown, hindering further functional studies. Here we identified and validated the lysine acetyltransferase (KAT) HBO1 as a “writer” of Kbz in mammalian cells. In addition, we report the first benzoylome in mammalian cells, identifying 1747 Kbz sites, among them at least 77 are the HBO1-targeted Kbz substrates. Bioinformatics analysis showed that HBO1-targeted Kbz sites were involved in multiple processes, including chromatin remodeling, transcription regulation, immune regulation, and tumor growth. Our results thus identify key regulatory elements of the Kbz pathway, and reveal new enzymatic activity and functions of HBO1 in cellular physiology.
Project description:We used ChIP-seq technology in order to map chromatin binding sites of the HBO1 MYST complex in the RKO cell line. We obtained a significant enrichment of the HBO1 signal right after TSS regions of genes and also In the proximal promoter region, with no signal on TSS. This enrichment also correlates with gene expression level. HBO1 signal in RKO cell line.
Project description:We find that 499 genes are up-regulated and 457 are down-regulated in response to over-expression of JADE1, while 397 genes are up-regulated and 385 are down-regulated after HBO1 knock-down. For each condition - HBO1 siRNA treatment or JADE1 over-expression - two biological replicates were analyzed in duplicate.
Project description:Chronic myelomonocytic leukemia (CMML) is an incurable hematopoietic stem cell malignancy. We identified a novel NUP98-HBO1 fusion from a patient with CMML. HBO1, a histone acetyltransferase (HAT) which belongs to the MYST family, is the first NUP98 fusion partner encodes HAT. To determine the effect of the NUP98-HBO1 fusion on downstream target gene regulation, we performed gene expression array analysis of NUP98-HBO1-transduced human cord blood (CB) CD34+ cells.
Project description:Lysine lactylation (Kla) links metabolism and gene regulation and plays a key role in multiple biological processes. We report that HBO1 functions as a lysine lactyltransferase to regulate transcription. Quantitative proteomic analysis further revealsed 95 endogenous Kla sites targeted by HBO1, with the majority located on histones.
Project description:The BRCA1 tumor suppressor has many functions in DNA damage repair, DNA replication, and beyond. Loss of any of these functions can lead to breast and ovarian carcinogenesis and also therapeutic sensitivity. In this study, we have discovered a novel role for BRCA1 in controlling replication initiation by regulating the bromodomain-protein BRD1 and the histone acetyltransferase HBO1. Specifically, we show that BRCA1 regulates localization of the BRD1-HBO1 complex to replication origins where the complex normally acetylates histone H3 on lysine 14. We performed chromatin-immunoprecipitation seqeuncing (ChIP-seq) for BRD1 and HBO1 in a BRCA1 mutant line (UWB1.289) and demonstrate that BRD1 and HBO1 co-occupy ORC2 binding sites and replication origins.
Project description:The mechanisms whereby the crucial pluripotency transcription factor Oct4 regulates target gene expression are incompletely understood. Using an assay system based on partially differentiated embryonic stem cells, we show that Oct4 opposes accumulation of local H3K9me2, and subsequent Dnmt3a-mediated DNA methylation. Upon binding DNA, Oct4 recruits the histone lysine demethylase Jmjd1c. ChIP timecourse experiments identify a stepwise Oct4 mechanism involving Jmjd1c recruitment and H3K9me2 demethylation, transient FACT complex recruitment, and nucleosome depletion. Genome-wide and targeted ChIP confirms binding of newly-synthesized Oct4, together with Jmjd1c and FACT, to the Pou5f1 enhancer and a small number of other Oct4 targets, including the Nanog promoter. Histone demethylation is required for both FACT recruitment and H3 depletion. Jmjd1c is required to induce endogenous Oct4 expression and fully reprogram fibroblasts to pluripotency, indicating that the assay system identifies functional Oct4 cofactors. These findings indicate that Oct4 sequentially recruits activities that catalyze histone demethylation and depletion. Examination of transcription factor occupancy in cells with newly synthesized Oct4.
Project description:The mechanisms whereby the crucial pluripotency transcription factor Oct4 regulates target gene expression are incompletely understood. Using an assay system based on partially differentiated embryonic stem cells, we show that Oct4 opposes accumulation of local H3K9me2, and subsequent Dnmt3a-mediated DNA methylation. Upon binding DNA, Oct4 recruits the histone lysine demethylase Jmjd1c. ChIP timecourse experiments identify a stepwise Oct4 mechanism involving Jmjd1c recruitment and H3K9me2 demethylation, transient FACT complex recruitment, and nucleosome depletion. Genome-wide and targeted ChIP confirms binding of newly-synthesized Oct4, together with Jmjd1c and FACT, to the Pou5f1 enhancer and a small number of other Oct4 targets, including the Nanog promoter. Histone demethylation is required for both FACT recruitment and H3 depletion. Jmjd1c is required to induce endogenous Oct4 expression and fully reprogram fibroblasts to pluripotency, indicating that the assay system identifies functional Oct4 cofactors. These findings indicate that Oct4 sequentially recruits activities that catalyze histone demethylation and depletion.