Dynamic extrinsic pacing of the HOX clock in human axial progenitors control motor neuron subtype specification
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PROVIDER: PRJNA642885 | ENA |
REPOSITORIES: ENA
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Project description:Rostro-caudal patterning of vertebrates depends on the temporally progressive activation of HOX genes within axial stem cells that fuel axial embryo elongation. Whether HOX genes sequential activation, the “HOX clock”, is paced by intrinsic chromatin-based timing mechanisms or by temporal changes in extrinsic cues remains unclear. Here, we studied HOX clock pacing in human pluripotent stem cells differentiating into spinal cord motor neuron subtypes which are progenies of axial progenitors. We show that the progressive activation of caudal HOX genes is controlled by a dynamic increase in FGF signaling. Blocking FGF pathway stalled induction of HOX genes, while precocious increase in FGF alone, or with GDF11 ligand, accelerated the HOX clock. Cells differentiated under accelerated HOX induction generated appropriate posterior motor neuron subtypes found along the human embryonic spinal cord. The HOX clock is thus dynamically paced by exposure parameters to secreted cues. Its manipulation by extrinsic factors alleviates temporal requirements to provide unprecedented synchronized access to human cells of multiple, defined, rostro-caudal identities for basic and translational applications.
2021-03-02 | GSE153519 | GEO
Project description:Hox and Cdx transcription factors regulate embryonic positional identities. Cdx mutant mice display posterior body truncations of the axial skeleton, neuraxis, and caudal uro-rectal structures. We show that trunk Hox genes stimulate axial extension as they can largely rescue these Cdx mutant phenotypes. Conversely, posterior (paralog group 13) Hox genes can prematurely arrest posterior axial growth when precociously expressed. Our data suggest that the transition from trunk to tail Hox gene expression successively regulates construction and termination of axial structures in the mouse embryo. Thus, Hox genes seem to differentially orchestrate posterior expansion of embryonic tissues during axial morphogenesis as an integral part of their function in specifying head-to-tail identity. In addition, we present evidence that Cdx and Hox transcription factors exert these effects by controlling Wnt signaling. Concomitant regulation of Cyp26a1 expression, restraining retinoic acid signaling in the posterior growth zone, may likewise play a role in timing the trunk-tail transition.
2009-10-19 | GSE17660 | GEO
Project description:Hox and Cdx transcription factors regulate embryonic positional identities. Cdx mutant mice display posterior body truncations of the axial skeleton, neuraxis, and caudal uro-rectal structures. We show that trunk Hox genes stimulate axial extension as they can largely rescue these Cdx mutant phenotypes. Conversely, posterior (paralog group 13) Hox genes can prematurely arrest posterior axial growth when precociously expressed. Our data suggest that the transition from trunk to tail Hox gene expression successively regulates construction and termination of axial structures in the mouse embryo. Thus, Hox genes seem to differentially orchestrate posterior expansion of embryonic tissues during axial morphogenesis as an integral part of their function in specifying head-to-tail identity. In addition, we present evidence that Cdx and Hox transcription factors exert these effects by controlling Wnt signaling. Concomitant regulation of Cyp26a1 expression, restraining retinoic acid signaling in the posterior growth zone, may likewise play a role in timing the trunk-tail transition.
2009-10-19 | GSE17658 | GEO
Project description:Vertebrate axial skeletal patterning is controlled by coordinated collinear expression of Hox genes and axial level-dependent activity of Hox protein combinations. Transcription factors of the Meis family act as cofactors of Hox proteins and profusely bind to Hox complex DNA, however their roles in mammalian axial patterning have not been established. Similarly, retinoic acid (RA) is known to regulate axial skeletal element identity through the transcriptional activity of its receptors, however whether this role is related to Meis/Hox regulation or functions in axial patterning remains unknown. Here we study the role of Meis factors in axial skeleton formation and its relationship to the RA pathway by characterizing Meis1, Meis2 and Raldh2 mutant mice. We report that Meis and Raldh2 regulate each other in a positive feedback regulatory loop that controls axial skeletal identity. Meis elimination produces homeotic transformations similar to those found in Raldh2 and anterior-Hox mutants and disrupts the expression of Hox target genes without changing the transcriptional profiles of Hox complexes. We propose that Meis regulates vertebrate axial skeleton patterning by exclusively affecting Hox protein function, and that alterations in RA levels can produce homeotic transformations without altering Hox transcription through regulating Meis expression.
2020-12-22 | GSE146301 | GEO
Project description:The axial skeleton of individual mammalian species exhibits remarkable robustness in the number and identity of vertebral elements that form(Owen 1853; Owen 1866; Narita and Kuratani 2005). Between mammalian species however, a great diversity in axial formulae has arisen due to natural selection(Narita and Kuratani 2005; Thewissen et al. 2006; Buchholtz 2007; Matsubara et al. 2017; Kingsley et al. 2017). The genetic mechanism(s) by which axial formulae in mammals is canalised, or manipulated to drive this diversity, remains a major question in biology. Here, we reveal three regulatory pathways essential in constraining total vertebral number and regional axial identity in the mouse. Specifically, the manipulation of Gdf11, Retinoic acid and microRNA-196 activity, individually and cumulatively, led to increasing total vertebral number and allowed us to understand the molecular logic constraining each major division of the vertebral column, from cervical through to tail vertebrae. All three pathways had differing control over Hox cluster expression, with heterochronic and quantitative changes in Hox expression found to parallel changes in axial identity. However, our work revealed an additional, and highly unexpected, role for Hox genes in supporting axial elongation within the tail region. This provides important support for an emerging view that mammalian Hox gene function is not limited to imparting positional identity as the mammalian body plan is laid down, and more broadly, this work provides a molecular framework with which to interrogate mechanisms of evolutionary change.
2023-08-31 | GSE157171 | GEO
Project description:The axial skeleton of individual mammalian species exhibits remarkable robustness in the number and identity of vertebral elements that form(Owen 1853; Owen 1866; Narita and Kuratani 2005). Between mammalian species however, a great diversity in axial formulae has arisen due to natural selection(Narita and Kuratani 2005; Thewissen et al. 2006; Buchholtz 2007; Matsubara et al. 2017; Kingsley et al. 2017). The genetic mechanism(s) by which axial formulae in mammals is canalised, or manipulated to drive this diversity, remains a major question in biology. Here, we reveal three regulatory pathways essential in constraining total vertebral number and regional axial identity in the mouse. Specifically, the manipulation of Gdf11, Retinoic acid and microRNA-196 activity, individually and cumulatively, led to increasing total vertebral number and allowed us to understand the molecular logic constraining each major division of the vertebral column, from cervical through to tail vertebrae. All three pathways had differing control over Hox cluster expression, with heterochronic and quantitative changes in Hox expression found to parallel changes in axial identity. However, our work revealed an additional, and highly unexpected, role for Hox genes in supporting axial elongation within the tail region. This provides important support for an emerging view that mammalian Hox gene function is not limited to imparting positional identity as the mammalian body plan is laid down, and more broadly, this work provides a molecular framework with which to interrogate mechanisms of evolutionary change.
2023-08-31 | GSE157172 | GEO
Project description:[original Title] Rapid and synchronous clearance of PcG histone modifications from Hox genes anticipates motor neuron differentiation. Hox genes are expressed in patterns that are spatially and temporally collinear with their chromosomal organization. This feature is an evolutionarily conserved hallmark of embryonic development, and in vertebrates it is critical, among others, for the specification of motor neuron subtypes and the wiring of sensory-motor circuits. We show here that the differentiation of motor neurons from stem cells is accompanied by a synchronous, domain-wide clearance of M-bM-^@M-^\repressiveM-bM-^@M-^] Polycomb (PcG)-dependent histone methylation from Hox gene chromatin domains. These findings argue against the idea, advanced recently, that the collinear dynamics of Hox gene expression invariably reflects the progressive clearance of repressive chromatin modifications. The rapid establishment of stable chromatin domains in response to a transient patterning signal likely serves as a molecular correlate of enduring rostro-caudal neural identity, which underlies the specification of postmitotic motor neuron subtype diversity and neuronal circuit assembly. The differentiation of ventral motor neurons is induced by treating embryonic stem cell cultures with retinoic acid and hedgehog agonist. Here, ChIP-chip using a custom Agilent array is used to profile the occupancy of H3K27me3, H3K4me3, and H3K79me2 at various defined stages during the differentiation process.
2013-07-04 | E-GEOD-19447 | biostudies-arrayexpress
Project description:[original Title] Rapid and synchronous clearance of PcG histone modifications from Hox genes anticipates motor neuron differentiation. Hox genes are expressed in patterns that are spatially and temporally collinear with their chromosomal organization. This feature is an evolutionarily conserved hallmark of embryonic development, and in vertebrates it is critical, among others, for the specification of motor neuron subtypes and the wiring of sensory-motor circuits. We show here that the differentiation of motor neurons from stem cells is accompanied by a synchronous, domain-wide clearance of “repressive” Polycomb (PcG)-dependent histone methylation from Hox gene chromatin domains. These findings argue against the idea, advanced recently, that the collinear dynamics of Hox gene expression invariably reflects the progressive clearance of repressive chromatin modifications. The rapid establishment of stable chromatin domains in response to a transient patterning signal likely serves as a molecular correlate of enduring rostro-caudal neural identity, which underlies the specification of postmitotic motor neuron subtype diversity and neuronal circuit assembly.
2013-07-04 | GSE19447 | GEO
Project description:Background: Freshwater planarians are well known for their regenerative abilities. Less well known is how planarians maintain spatial patterning in long-lived adult animals or how they re-pattern tissues during regeneration. HOX genes are good candidates to regulate planarian spatial patterning, yet the full complement or genomic clustering of planarian HOX genes has not yet been described, primarily because only a few have been detectable by in situ hybridization, and none have given morphological phenotypes when knocked down by RNAi. Results: Because the planarian Schmidtea mediterranea (S. med) is unsegmented, appendage-less, and morphologically simple, it has been proposed that it may have a simplified HOX gene complement. Here we argue against this hypothesis and show that S. med has a total of 13 HOX genes, which represent homologs to all major axial categories, and can be detected by whole-mount in situ hybridization using a highly-sensitive method. In addition, we show that planarian HOX genes do not cluster in the genome, yet 5/13 have retained aspects of axially-restricted expression. Finally, we confirm HOX gene axial expression by RNA-deep-sequencing 6 anterior-to-posterior “zones” of the animal, which we provide as a dataset to the community to discover other axially-restricted transcripts. Conclusions: Freshwater planarians have an unappreciated HOX gene complexity, with all major axial categories represented. However, we conclude based on adult expression patterns that planarians have a derived body plan and their asexual lifestyle may have allowed for large changes in HOX expression from the last common ancestor between arthropods, flatworms, and vertebrates. Using our in situ method and axial zone RNAseq data, it should be possible to further understand the pathways that pattern the anterior-posterior axis of adult planarians.
2016-03-08 | GSE78937 | GEO
Project description:In vertebrate embryos, anterior tissues are generated early, followed by the other axial structures that emerge sequentially from a posterior growth zone. The genetic network driving posterior axial elongation in mice, and its disturbance in mutants with posterior truncation are not yet fully understood. We show that the combined expression of Cdx2 and T Brachyury is essential to establish the core signature of posterior axial progenitors. Cdx2 and T Brachyury are required for extension of a similar trunk portion of the axis. Simultaneous loss of function of these two genes disrupts axial elongation to a much greater extent than each single mutation alone. We identify and validate common targets for Cdx2 and T Brachyury in vivo including Wnt and Fgf pathway components active in the axial progenitor niche. Our data demonstrate that integration of the Cdx/Hox and T Brachyury transcriptional networks controls differential axial growth during vertebrate trunk elongation.
2016-12-20 | GSE84899 | GEO