A transcriptional switch in a novel non-canonical, ßcatenin dependent Wnt pathway controls axon midline decisions
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA551612 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR9610920.fastq.gz | Fastqsanger.gz | |||
| SRR9610921.fastq.gz | Fastqsanger.gz | |||
| SRR9610922.fastq.gz | Fastqsanger.gz | |||
| SRR9610923.fastq.gz | Fastqsanger.gz | |||
| SRR9610924.fastq.gz | Fastqsanger.gz |
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Project description:During the establishment of neuronal connections, axons must correctly navigate long pathways to find their targets. By focusing on the guidance of visual axons at the midline, we describe for the first time that a switch in a novel branch of the Wnt pathway, which is not the canonical or the non-canonical, that controls axonal directionality. This finding conciliates the current debate about the participation of the Wnt pathways in axon pathfinding. We then identify the transcription factor (TF) Zic2 as the regulator of this switch and describe the entire set of genes regulated by it. Also, although previous genome-wide approaches have not retrieved the binding motif for this TF, we report here a de novo Zic2 binding motif that is located in promoter and intragenic regions. In addition, we find that the tyrosine kinase EphB receptor, which is one of the genes induced by Zic2, interferes with the Wnt pathway by phosphorylating betacatenin at the growth cone and inducing its asymmetric detachment from the membrane to promote axon steering.
2020-11-19 | GSE133492 | GEO
Project description:Axon pathfinding is a key step during the formation of neural circuits but however the transcriptional mechanisms regulating its progression remain poorly understood. The binary decision of crossing or avoiding the midline that neurons make during developmente midline that mammalian retinal ganglion cell (RGC) axons take at the optic chiasm has classically represented a robust model to search for novel mechanisms controlling the selection of axonal trajectories. Here, in order to identify new axon pathfinding regulators, we compared the transcriptome and chromatin accessibility profiles of mammalian retinal ganglion cells RGCs projecting ipsilateral (iRGCs) or contralaterally (cRGCs). Overall, our analyses retrieved dozens of new molecules potentially involved in axon pathfinding and uncovered the regulatory logic behind axon trajectories selection.
2022-08-22 | GSE184275 | GEO
Project description:During the development of the Drosophila central nervous system the process of midline crossing is orchestrated by a number of guidance receptors and ligands. Many key axon guidance molecules have been identified in both invertebrates and vertebrates, but the transcriptional regulation of growth cone guidance remains largely unknown. One open question is whether transcriptional regulation plays a role in midline crossing, or if local translation can account for the necessary fine tuning of protein levels. To investigate this issue, we conducted a genome wide analysis of transcription in Drosophila embryos using wild type and a number of well-characterized Drosophila guidance mutants and transgenics. We also analyzed a publicly available microarray time course of Drosophila embryonic development with an axon guidance focus. Using hopach, a novel clustering method which is well suited to microarray data analysis, we identified groups of genes with similar expression patterns across guidance mutants and transgenics. We then systematically characterized the resulting clusters with respect to their relevance to axon guidance using two complementary controlled vocabularies: the Gene Ontology (GO) and anatomical annotations of the Atlas of Pattern of Gene Expression (APoGE) in situ hybridization database. The analysis indicates that regulation of gene expression does play a role in the process of axon guidance in Drosophila. We also find a strong link between axon guidance and hemocyte migration, a result that agrees with mounting evidence that axon guidance molecules are co-opted in vertebrate vascularization. Cell cyclin activity in the context of axon guidance is also suggested from our array data. RNA and protein patterns of cell cyclin in axon guidance mutants and transgenics support this possible link. This study provides important insights into the regulation of axon guidance in vivo and suggests that transcription does play a role in control of axon guidance. Keywords: Mutant Analysis
2006-12-14 | GSE6515 | GEO
Project description:Precise wiring of the nervous system depends on coordinating the action of conserved families of proteins that direct axons to their appropriate targets. Slit-roundabout repulsion and netrin-deleted in colorectal cancer (DCC) (frazzled) attraction must be tightly regulated to control midline axon guidance in vertebrates and invertebrates, but the mechanism mediating this regulation is poorly defined. Here, we show that the Fra receptor has two genetically separable functions in regulating midline guidance in Drosophila. First, Fra mediates canonical chemoattraction in response to netrin, and, second, it functions independently of netrin to activate commissureless transcription, allowing attraction to be coupled to the down-regulation of repulsion in precrossing commissural axons.
| S-EPMC4078765 | biostudies-literature
Project description:During the development of the Drosophila central nervous system the process of midline crossing is orchestrated by a number of guidance receptors and ligands. Many key axon guidance molecules have been identified in both invertebrates and vertebrates, but the transcriptional regulation of growth cone guidance remains largely unknown. One open question is whether transcriptional regulation plays a role in midline crossing, or if local translation can account for the necessary fine tuning of protein levels. To investigate this issue, we conducted a genome wide analysis of transcription in Drosophila embryos using wild type and a number of well-characterized Drosophila guidance mutants and transgenics. We also analyzed a publicly available microarray time course of Drosophila embryonic development with an axon guidance focus. Using hopach, a novel clustering method which is well suited to microarray data analysis, we identified groups of genes with similar expression patterns across guidance mutants and transgenics. We then systematically characterized the resulting clusters with respect to their relevance to axon guidance using two complementary controlled vocabularies: the Gene Ontology (GO) and anatomical annotations of the Atlas of Pattern of Gene Expression (APoGE) in situ hybridization database. The analysis indicates that regulation of gene expression does play a role in the process of axon guidance in Drosophila. We also find a strong link between axon guidance and hemocyte migration, a result that agrees with mounting evidence that axon guidance molecules are co-opted in vertebrate vascularization. Cell cyclin activity in the context of axon guidance is also suggested from our array data. RNA and protein patterns of cell cyclin in axon guidance mutants and transgenics support this possible link. This study provides important insights into the regulation of axon guidance in vivo and suggests that transcription does play a role in control of axon guidance. Experiment Overall Design: Several mutants and transgenics were analyzed, totalizing 17 distinct conditions. Individual descriptions are included in each microarray. For each condition there are 3 or 4 replicates. The file's name indicates the replicates, e.g., comm.a reflects the replicate a of mutant commissureless. The experiment design covers a range of mutants and transgenics of key axon guidance mutans, in different dosages. The protocol was the standard Affymetrix protocol.
2008-06-15 | E-GEOD-6515 | biostudies-arrayexpress
Project description:RNA-based regulatory mechanisms play important roles in the development and plasticity of neural circuits and neurologic disease. Developing axons provide a well suited model to study RNA-based regulation, and contain specific subsets of mRNAs that are locally translated and have roles in axon pathfinding. However, the RNA-binding proteins involved in axon pathfinding, and their corresponding mRNA targets, are still largely unknown. Here we find that the RNA-binding protein IMP2 (Igf2bp2) is strikingly enriched in developing axon tracts, including in spinal commissural axons. We used the HITS-CLIP approach to perform a genome-wide identification of RNAs that interact directly with IMP2 in the native context of developing brain. This IMP2 interactome was highly enriched for mRNA targets related to axon guidance. Accordingly, IMP2 knockdown in the developing spinal cord led to strong defects in commissural axon trajectories at the midline intermediate target. These results reveal a highly distinctive axonal enrichment of IMP2, show that it interacts with a network of axon guidance-related mRNAs, and reveal its requirement for normal axon pathfinding during vertebrate development. CLIP-seq
2016-08-02 | E-GEOD-83822 | biostudies-arrayexpress
Project description:RNA-based regulatory mechanisms play important roles in the development and plasticity of neural circuits and neurologic disease. Developing axons provide a well suited model to study RNA-based regulation, and contain specific subsets of mRNAs that are locally translated and have roles in axon pathfinding. However, the RNA-binding proteins involved in axon pathfinding, and their corresponding mRNA targets, are still largely unknown. Here we find that the RNA-binding protein IMP2 (Igf2bp2) is strikingly enriched in developing axon tracts, including in spinal commissural axons. We used the HITS-CLIP approach to perform a genome-wide identification of RNAs that interact directly with IMP2 in the native context of developing brain. This IMP2 interactome was highly enriched for mRNA targets related to axon guidance. Accordingly, IMP2 knockdown in the developing spinal cord led to strong defects in commissural axon trajectories at the midline intermediate target. These results reveal a highly distinctive axonal enrichment of IMP2, show that it interacts with a network of axon guidance-related mRNAs, and reveal its requirement for normal axon pathfinding during vertebrate development.
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Project description:In the developing spinal cord, Sonic hedgehog (Shh) attracts commissural axons toward the floor plate. How Shh regulates the cytoskeletal remodeling that underlies growth cone turning is unknown. We found that Shh-mediated growth cone turning requires the activity of Docks, which are unconventional GEFs. Knockdown of Dock3 and 4, or their binding partner ELMO1 and 2, abolished commissural axon attraction by Shh in vitro. Dock3/4 and ELMO1/2 were also required for correct commissural axon guidance in vivo. Polarized Dock activity was sufficient to induce axon turning, indicating that Docks are instructive for axon guidance. Mechanistically, we show that Dock and ELMO interact with Boc, the Shh receptor, and that this interaction is reduced upon Shh stimulation. Furthermore, Shh stimulation translocates ELMO to the growth cone periphery and activates Rac1. This identifies Dock/ELMO as an effector complex of non-canonical Shh signaling and demonstrates the instructive role of GEFs in axon guidance.
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Project description:Thyroid hormones (TH) are powerful regulators of metabolism with major effects on body weight, cholesterol, and liver fat that have been exploited pharmacologically for many years. Activation of gene expression by TH action is canonically ascribed to a hormone- dependent “switch” from corepressor to activator binding to thyroid hormone receptors (TR), while the mechanism of TH-dependent repression is controversial. To address this, we generated a mouse line in which endogenous TRβ1 was epitope-tagged to allow precise chromatin immunoprecipitation at the low physiological levels of TR, and defined high confidence binding sites where TR functioned at enhancers regulated in the same direction as the nearest gene in a TRβ-dependent manner. Remarkably, although positive and negative regulation by TH have been ascribed to different mechanisms, TR binding was highly enriched at canonical DR4 motifs irrespective of the transcriptional direction of the enhancer. The canonical NCoR1/HDAC3 corepressor complex was reduced but not completely dismissed by TH and, surprisingly, similar effects were seen at enhancers associated with negatively as well as positively regulated genes. Conversely, coactivator CBP was found at all TH-regulated enhancers, with transcriptional activity correlating with the ratio of CBP to NCoR rather than their presence or absence. These results demonstrate that, in contrast to the canonical “all or none” coregulator switch model, TH regulates gene expression by orchestrating a shift in the relative binding of corepressors and coactivators.
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