Project description:Cell type-specific master transcription factors (MTFs) play vital roles in defining cell identity and function. However, the roles ubiquitous factors play in the specification of cell identity remain underappreciated. Here we show that all three subunits of the ubiquitous heterotrimeric CCAAT-binding NF-Y complex are required for the maintenance of embryonic stem cell (ESC) identity, and establish NF-Y as a novel component of the core pluripotency network. Genome-wide occupancy and transcriptomic analyses in ESCs and neurons reveal that not only does NF-Y regulate genes with housekeeping functions through cell type-invariant promoter-proximal binding, but also genes required for cell identity by binding to cell type-specific enhancers with MTFs. Mechanistically, NF-Y's distinctive DNA-binding mode promotes MTF binding at enhancers by facilitating a permissive chromatin conformation. Our studies unearth a novel function for NF-Y in promoting chromatin accessibility, and suggest that other proteins with analogous structural and DNA-binding properties may function in similar ways. Genome-wide mapping of NF-YA, NF-YB, and NF-YC subunits of the NF-Y complex in mouse ESCs, and microarray gene expression profiling of control knockdown (KD), NF-YA KD, NF-YB KD, NF-YC KD, and NF-YA/NF-YB/NF-YC triple KD ESCs.
Project description:Cell type-specific master transcription factors (MTFs) play vital roles in defining cell identity and function. However, the roles ubiquitous factors play in the specification of cell identity remain underappreciated. Here we show that all three subunits of the ubiquitous heterotrimeric CCAAT-binding NF-Y complex are required for the maintenance of embryonic stem cell (ESC) identity, and establish NF-Y as a novel component of the core pluripotency network. Genome-wide occupancy and transcriptomic analyses in ESCs and neurons reveal that not only does NF-Y regulate genes with housekeeping functions through cell type-invariant promoter-proximal binding, but also genes required for cell identity by binding to cell type-specific enhancers with MTFs. Mechanistically, NF-Y's distinctive DNA-binding mode promotes MTF binding at enhancers by facilitating a permissive chromatin conformation. Our studies unearth a novel function for NF-Y in promoting chromatin accessibility, and suggest that other proteins with analogous structural and DNA-binding properties may function in similar ways. Genome-wide mapping of NF-YA, NF-YB, and NF-YC subunits of the NF-Y complex in mouse ESCs, and microarray gene expression profiling of control knockdown (KD), NF-YA KD, NF-YB KD, NF-YC KD, and NF-YA/NF-YB/NF-YC triple KD ESCs.
Project description:Development of eukaryotic organisms is controlled by transcription factors that trigger specific and global changes in gene expression programmes. In plants, MADS-domain transcription factors act as master regulators of developmental switches and organ specification. However, the mechanisms by which these factors dynamically regulate the expression of their target genes at different developmental stages are still poorly understood. Here, we characterize the dynamic relationship of chromatin accessibility, gene expression and DNA-binding of two MADS-domain proteins during Arabidopsis flower development. The developmental dynamics of DNA-binding of APETALA1 and SEPALLATA3 is largely independent of chromatin accessibility, and our findings suggest that AP1 acts as M-bM-^@M-^Xpioneer factorM-bM-^@M-^Y that modulates chromatin accessibility, thereby facilitating access of other transcriptional regulators to their target genes. Our data provide a primer to the idea that cellular differentiation in plants can be associated to dynamic changes in chromatin accessibility, as consequence of the action of master transcription factors. We used the AP1-GR system to conduct DNaseI hypersensitivity experiments at different stages of flower development. Samples were generated from tissue in which the AP1-GR protein was induced using a treatment of 1 uM DEX to the shoot apex. The material was collect before treatment and 2, 4 and 8 days after treatment. As control, naked DNA from wild-type inflorescences was used. Experiments were done in two biological replicates. The GSE47981 includes expression data that are complementary to the data in the GSE46986 and GSE46894.
Project description:The conserved histone locus body (HLB) assembles prior to zygotic gene activation early during development and concentrates factors into a nuclear domain of coordinated histone gene regulation. Although HLBs form specifically at replication dependent histone loci, the cis and trans factors that target HLB components to histone genes remained unknown. Here we report that conserved GA-repeat cis elements within the bidirectional histone3-histone4 promoter direct HLB formation in Drosophila. In addition, the CLAMP zinc-finger protein binds these GA-repeat motifs, increases chromatin accessibility, enhances histone gene transcription, and promotes HLB formation. We previously demonstrated that CLAMP also promotes the formation of another domain of coordinated gene regulation: the dosage-compensated male X-chromosome. Therefore, CLAMP binding to GA-repeat motifs promotes the formation of two distinct domains of coordinated gene activation located at different places in the genome.
Project description:Nuclear Factor Y (NF-Y) is a heterotrimeric transcription factor that binds CCAAT elements. The NF-Y trimer is composed of a Histone Fold Domain (HFD) dimer (NF-YB/NF-YC) and NF-YA, which confers DNA sequence specificity. NF-YA shares a conserved domain with the CONSTANS, CONSTANS-LIKE, TOC1 (CCT) proteins. We show that CONSTANS (CO/B-BOX PROTEIN1 BBX1), a master flowering regulator, forms a trimer with Arabidopsis thaliana NF-YB2/NF-YC3 to efficiently bind the CORE element of the FLOWERING LOCUS T promoter. Using saturation mutagenesis, electrophoretic mobility shift assays, and RNA-sequencing profiling of co, nf-yb, and nf-yc mutants, we identify CCACA elements as the core NF-CO binding site. CO physically interacts with the same HFD surface required for NF-YA association, as determined by mutations in NF-YB2 and NF-YC9, and tested in vitro and in vivo. The co-7 mutation in the CCT domain, corresponding to an NF-YA arginine directly involved in CCAAT recognition, abolishes NF-CO binding to DNA
Project description:The conserved histone locus body (HLB) assembles prior to zygotic gene activation early during development and concentrates factors into a nuclear domain of coordinated histone gene regulation. Although HLBs form specifically at replication-dependent histone loci, the cis and trans factors that target HLB components to histone genes remained unknown. Here we report that conserved GA repeat cis elements within the bidirectional histone3-histone4 promoter direct HLB formation in Drosophila In addition, the CLAMP (chromatin-linked adaptor for male-specific lethal [MSL] proteins) zinc finger protein binds these GA repeat motifs, increases chromatin accessibility, enhances histone gene transcription, and promotes HLB formation. We demonstrated previously that CLAMP also promotes the formation of another domain of coordinated gene regulation: the dosage-compensated male X chromosome. Therefore, CLAMP binding to GA repeat motifs promotes the formation of two distinct domains of coordinated gene activation located at different places in the genome.
Project description:The inhibitor of kB kinase (IKK) is the master regulator of the nuclear factor kB (NF-kB) pathway, involved in inflammatory, immune and apoptotic responses. In the ‘canonical’ NF-kB pathway, IKK phosphorylates inhibitor of kB (IkB) proteins and this triggers ubiquitin-mediated degradation of IkB, leading to release and nuclear translocation of NF-B transcription factors.
The data presented show that the IKK and IKK subunits recognize a YDDX docking site located within the disordered C-terminal region of IkBa. Our results also suggest that IKK contributes to the docking interaction with higher affinity as compared to IKK.
Project description:Development of eukaryotic organisms is controlled by transcription factors that trigger specific and global changes in gene expression programmes. In plants, MADS-domain transcription factors act as master regulators of developmental switches and organ specification. However, the mechanisms by which these factors dynamically regulate the expression of their target genes at different developmental stages are still poorly understood. Here, we characterize the dynamic relationship of chromatin accessibility, gene expression and DNA-binding of two MADS-domain proteins during Arabidopsis flower development. The developmental dynamics of DNA-binding of APETALA1 and SEPALLATA3 is largely independent of chromatin accessibility, and our findings suggest that AP1 acts as 'pioneer factor' that modulates chromatin accessibility, thereby facilitating access of other transcriptional regulators to their target genes. Our data provide a primer to the idea that cellular differentiation in plants can be associated to dynamic changes in chromatin accessibility, as consequence of the action of master transcription factors. We used the AP1-GR system to conduct chromatin immunoprecipitation experiments with SEP3-specific antibodies and GR atibodies followed by deep-sequencing (ChIP-Seq) in order to determine SEP3 and AP1 binding sites on a genome-wide scale. Samples were generated from tissue in which the AP1-GR protein was induced using a treatment of 1 uM DEX to the shoot apex. The material was collect 2, 4 and 8 days after treatment. As control, we performed ChIP experiments using pre-immune serum at the different time points. Experiments were done in two biological replicates for 4 days and 8 days time-points while one biological replicate was done for control samples and 2 days time-point. The GSE47981 includes expression data that are complementary to the data in the GSE46986 and GSE46894.