Similar Datasets
Project description:During the essential and conserved process of zygotic genome activation (ZGA), chromatin accessibility must increase to promote transcription. Drosophila is a well-established model for defining mechanisms that drive ZGA. Zelda (ZLD) is a key pioneer transcription factor (TF) that promotes ZGA in the Drosophila embryo. However, many genomic loci that contain GA-rich motifs become accessible during ZGA independent of ZLD. Therefore, we hypothesized that other early TFs that function with ZLD have not yet been identified, especially those that are capable of binding to GA-rich motifs such as chromatin-linked adaptor for male-specific lethal (MSL) proteins (CLAMP). Here, we demonstrate that Drosophila embryonic development requires maternal CLAMP to (1) activate zygotic transcription; (2) increase chromatin accessibility at promoters of specific genes that often encode other essential TFs; and (3) enhance chromatin accessibility and facilitate ZLD occupancy at a subset of key embryonic promoters. Thus, CLAMP functions as a pioneer factor that plays a targeted yet essential role in ZGA.
| S-EPMC8367384 | biostudies-literature
Project description:The pioneer transcription factor Zelda (ZLD) increases the accessibility of chromatin to promote the essential process of zygotic genome activation (ZGA) in the Drosophila early embryo. However, many genomic loci remain accessible in the absence of ZLD and are enriched for GA-rich DNA binding motifs. Therefore, we hypothesized that other pioneer TFs that function with ZLD have not yet been identified, especially those that bind to GA-rich motifs. CLAMP (Chromatin-linked adaptor for Male-specific lethal MSL proteins) is a GA-rich motif binding TF that is essential for early embryonic development. Here, we identify for the first time that CLAMP is a pioneer TF which interacts directly with nucleosomes, regulates zygotic genome activation, promotes chromatin accessibility, and facilitates the binding of ZLD to promoters. When ZLD is bound at a locus but does not regulate chromatin accessibility, CLAMP can often function redundantly to open the chromatin. Because ZGA is an essential process across metazoans, it is key to evolve redundant pioneer TFs to protect organisms from lethality that would be caused by loss of a single non-redundant factor.
2021-08-05 | GSE152598 | GEO
Project description:The pioneer transcription factor Zelda (ZLD) increases the accessibility of chromatin to promote the essential process of zygotic genome activation (ZGA) in the Drosophila early embryo. However, many genomic loci remain accessible in the absence of ZLD and are enriched for GA-rich DNA binding motifs. Therefore, we hypothesized that other pioneer TFs that function with ZLD have not yet been identified, especially those that bind to GA-rich motifs. CLAMP (Chromatin-linked adaptor for Male-specific lethal MSL proteins) is a GA-rich motif binding TF that is essential for early embryonic development. Here, we identify for the first time that CLAMP is a pioneer TF which interacts directly with nucleosomes, regulates zygotic genome activation, promotes chromatin accessibility, and facilitates the binding of ZLD to promoters. When ZLD is bound at a locus but does not regulate chromatin accessibility, CLAMP can often function redundantly to open the chromatin. Because ZGA is an essential process across metazoans, it is key to evolve redundant pioneer TFs to protect organisms from lethality that would be caused by loss of a single non-redundant factor.
2021-08-05 | GSE152596 | GEO
Project description:CLAMP and Zelda function together as pioneer transcription factors to promote Drosophila zygotic genome activation
| PRJNA639826 | ENA
Project description:CLAMP and Zelda function together as pioneer transcription factors to promote Drosophila zygotic genome activation [ATAC-Seq]
| PRJNA639809 | ENA
Project description:CLAMP and Zelda function together as pioneer transcription factors to promote Drosophila zygotic genome activation [ChIP-Seq]
| PRJNA639811 | ENA
Project description:Reprogramming cell fate during the first stages of embryogenesis requires that transcriptional activators gain access to the genome and remodel the zygotic transcriptome. Nonetheless, it is not clear whether the continued activity of these pioneering factors is required throughout zygotic genome activation or whether they are only required early to establish cis-regulatory regions. To address this question, we developed an optogenetic strategy to rapidly and reversibly inactivate the master regulator of genome activation in Drosophila, Zelda. Using this strategy, we demonstrate that continued Zelda activity is required throughout genome activation. We show that Zelda binds DNA in the context of nucleosomes and suggest that this allows Zelda to occupy the genome despite the rapid division cycles in the early embryo. These data identify a powerful strategy to inactivate transcription factor function during development and suggest that reprogramming in the embryo may require specific, continuous pioneering functions to activate the genome.
| S-EPMC6544384 | biostudies-literature
Project description:The Drosophila genome activator Vielfaltig (Vfl), also known as Zelda (Zld), is thought to prime enhancers for activation by patterning transcription factors (TFs). Such priming is accompanied by increased chromatin accessibility, but the mechanisms by which this occurs are poorly understood. Here, we analyze the effect of Zld on genome-wide nucleosome occupancy and binding of the patterning TF Dorsal (Dl). Our results show that early enhancers are characterized by an intrinsically high nucleosome barrier. Zld tackles this nucleosome barrier through local depletion of nucleosomes with the effect being dependent on the number and position of Zld motifs. Without Zld, Dl binding decreases at enhancers and redistributes to open regions devoid of enhancer activity. We propose that Zld primes enhancers by lowering the high nucleosome barrier just enough to assist TFs in accessing their binding motifs and promoting spatially controlled enhancer activation if the right patterning TFs are present. We envision that genome activators in general will utilize this mechanism to activate the zygotic genome in a robust and precise manner.
| S-EPMC4617966 | biostudies-literature
Project description:Reprogramming cell fate during the first stages of embryogenesis requires that transcriptional activators gain access to the genome and remodel the zygotic transcriptome. Nonetheless, it is not clear if the continued activity of these pioneering factors is required throughout zygotic genome activation or if they are only required early to establish cis-regulatory regions. To address this question, we developed an optogenetic strategy to rapidly and reversibly inactivate the master regulator of genome activation in Drosophila, Zelda. Using this strategy, we demonstrated that continued Zelda activity is required throughout genome activation. We showed that Zelda binds DNA in the context of nucleosomes and suggest that this allows Zelda to occupy the genome despite the rapid division cycles in the early embryo. These data identify a powerful strategy to inactivate transcription factor function during development and suggest that reprogramming in the embryo may require specific, continuous pioneering functions to activate the genome.
2019-02-06 | GSE121157 | GEO
Project description:Because chromatin determines whether information encoded in DNA is accessible to transcription factors, dynamic chromatin states in development may constrain how gene regulatory networks impart embryonic pattern. To determine the interplay between chromatin states and regulatory network function, we performed ATAC-seq on Drosophila embryos during the establishment of the segmentation network, comparing wild-type and mutant embryos in which all graded maternal patterning inputs are eliminated. While during the period between zygotic genome activation and gastrulation many regions maintain stable accessibility, cis-regulatory modules (CRMs) within the network undergo extensive patterning-dependent changes in accessibility. A component of the network, Odd-paired (opa), is necessary for pioneering accessibility of late segmentation network CRMs. opa-driven changes in accessibility are accompanied by equivalent changes in gene expression. Interfering with the timing of opa activity impacts the proper patterning of expression. These results indicate that dynamic systems for chromatin regulation directly impact the reading of embryonic patterning information.
| S-EPMC7190358 | biostudies-literature