Functional Analysis of Regional Gene Expression in Zebrafish Craniofacial Development
Ontology highlight
ABSTRACT: Patterning of the facial skeleton involves the precise deployment of thousands of genes in distinct regions of the pharyngeal arches. Despite their significance for craniofacial development, how genetic programs drive this regionalization remains poorly understood. Here we use combinatorial labeling of zebrafish cranial neural crest-derived cells (CNCCs) to define global gene expression along the dorsoventral axis of the developing arches. Intersection of region-specific transcriptomes with expression changes in response to signaling perturbations demonstrates complex roles for Endothelin1 (Edn1) signaling in the intermediate joint-forming region yet a surprisingly minor role in ventral-most regions. Analysis of co-variance across multiple sequencing experiments further reveals clusters of co-regulated genes, with in situ hybridization confirming the expression of novel genes with domain-specific expression. We then performed mutational analysis of a number of these genes, which uncovered antagonistic functions of two Edn1 targets, follistatin a (fsta) and emx2, in regulating cartilaginous joints in the hyoid arch. Our unbiased discovery and functional analysis of genes with regional expression in arch CNCCs reveals complex regulation by Edn1 and points to novel candidates for craniofacial disorders.
Project description:The overall goal of this project is to investigate the role of TGF-beta signaling in tissue-tissue interactions between myogenic precursors of craniofacial muscles and cranial neural crest cells (CNCCs). Here, we conducted gene expression profiling of the mandibular arch from mice at embryonic day E11.5 with a CNCC-specific conditional inactivation of the TGF-beta receptor type 1 gene Alk5. These mice provide a model of microglossia as well as disrupted extraocular and masticatory muscle development, which are congenital birth defects commonly observed in several syndromic conditions. To investigate the adverse effects of dysfunctional TGF-beta signaling on tissue-tissue interactions between CNCCs and myogenic precursors of craniofacial muscles, we analyzed mandibular arch tissue of mice with a CNCC-specific conditional inactivation of Alk5 (Wnt1-Cre; Alk5 fl/fl). We performed microarray analyses of the mandibular arch of Alk5 fl/fl control mice and Wnt1-Cre; Alk5 fl/fl mutant mice, collected at embryonic day E11.5 (n=4 per group).
Project description:Distinct shaping of the upper versus lower facial skeleton is essential for function of the vertebrate jaw and middle ear, yet the cellular mechanisms by which this occurs have remained unclear. Here, we show that Endothelin1 (Edn1) signaling accelerates mesenchymal condensation and subsequent cartilage formation in the lower face through antagonism of Jagged-Notch signaling and Prrx1 transcription factors. A genomic analysis of facial skeletal precursors in mutants and overexpression embryos reveals that Jagged-Notch signaling represses genes that are strongly induced as pharyngeal arch neural crest-derived cells begin skeletal differentiation. In wild types, initial Jagged-Notch repression dorsally ensures that barx1+ condensations and cartilage differentiation occur first in ventral-intermediate zones of the pharyngeal arches. Reduced Jagged-Notch signaling results in an expansion of pre-cartilage condensations in the upper face, with loss of barx1 partially restoring dorsal cartilage shapes in jag1b mutants. Further, by studying new mutants for zebrafish prrx1a and prrx1b, we find that Prrx1 genes function in parallel to Jagged-Notch signaling to restrict the formation of dorsal barx1+ pre-cartilage condensations. Consistently, combined losses of jag1b and prrx1a/b robustly rescue ventral barx1+ condensations and lower facial cartilage development in edn1 mutants. Together, our work suggests that Edn1 works through parallel inhibition of Jagged-Notch and Prrx1 pathways to promote an earlier and more extensive establishment of cartilage condensations in the lower face. We performed RNAseq on FACS-sorted neural crest-derived pharyngeal arch cells (fli1a:GFP; sox10:DsRed double positive) from wild-type embryos at 3 different stages (20, 28, and 36 hours post fertilization) and embryos with altered levels of Edn1 and Notch signaling (edn1 mutants and hsp70I:Gal4; UAS:Edn1 transgenics; jag1b mutants, dibenzazepine-treated embryos, and hsp70I:Gal4; UAS:NICD transgenics. We also sequenced RNA from heat-shocked UAS:Edn1+ and hsp70I:Gal4+ transgenics and jag1b+/+ controls.
Project description:The Dlx homeobox genes have central roles in controlling patterning and differentiation of the brain and craniofacial primordia. In the brain, loss of Dlx function results in defects in the production, migration and differentiation of GABAergic neurons, that can lead to epilepsy. In the branchial arches, loss of Dlx function leads to craniofacial malformations that include trigeminal axon pathfinding defects. To determine how these genes function, we wish to identify the transcriptional circuitry that lies downstream of these transcription factors by comparing gene expression in wild type with Dlx mutant CNS and craniofacial tissues. 1) Compare gene expression in the maxillay branch of the first branchial arch (BA) of E10.5 wild type and Dlx2 -/- mutants. 2) Compare gene expression in the maxillary branch of the first BA of E10.5 wild type and Dlx1/2 -/- mutants. 3) Compare gene expression in wild type maxillary and mandibular branchial arches. 4) Compare gene expressionin mandibular branch of Dlx5/6 -/- mutants with wild type mandibular branch. The Dlx transcription factors are essential for controlling patterning of the brain and craniofacial primordia. In the brain, they control differentiation of GABAergic neurons of the basal ganglia. In the branchial arches, they control regional patterning. I hypothesize that there will be some conserved and some divergent mechanisms that the Dlx genes use in controlling brain and craniofacial development. We have already performed array analyses on Dlx function in the developing basal ganglia (with TGEN) by comparing expressed genes in wild type and Dlx1/2 mutants. Here we will compare gene expression in the brachial arches of wild type and Dlx mutant mice. 1) Generate E10.5 mouse embryos that are either wild type, Dlx2-/-, Dlx1/2 -/- or Dlx5/6 -/-. 2) Determine genotype by PCR. 3) Dissect branchial arches from the different genotypes. 4) Separate maxillary and mandibular branch of each branchial arch. 5) Prepare total RNA from the specimens. Obtain sufficient tissue to obtain 10 ug of total RNA - based on previous experience we anticipate that this will require ~ 10 branchial arches. We will pool the tissue from different embryos of the same genotype. 6) Send total RNA to TGEN for probe preparation, hybridization and array result analysis.
Project description:The Dlx homeobox genes have central roles in controlling patterning and differentiation of the brain and craniofacial primordia. In the brain, loss of Dlx function results in defects in the production, migration and differentiation of GABAergic neurons, that can lead to epilepsy. In the branchial arches, loss of Dlx function leads to craniofacial malformations that include trigeminal axon pathfinding defects. To determine how these genes function, we wish to identify the transcriptional circuitry that lies downstream of these transcription factors by comparing gene expression in wild type with Dlx mutant CNS and craniofacial tissues. 1) Compare gene expression in the maxillay branch of the first branchial arch (BA) of E10.5 wild type and Dlx2 -/- mutants. 2) Compare gene expression in the maxillary branch of the first BA of E10.5 wild type and Dlx1/2 -/- mutants. 3) Compare gene expression in wild type maxillary and mandibular branchial arches. 4) Compare gene expressionin mandibular branch of Dlx5/6 -/- mutants with wild type mandibular branch. The Dlx transcription factors are essential for controlling patterning of the brain and craniofacial primordia. In the brain, they control differentiation of GABAergic neurons of the basal ganglia. In the branchial arches, they control regional patterning. I hypothesize that there will be some conserved and some divergent mechanisms that the Dlx genes use in controlling brain and craniofacial development. We have already performed array analyses on Dlx function in the developing basal ganglia (with TGEN) by comparing expressed genes in wild type and Dlx1/2 mutants. Here we will compare gene expression in the brachial arches of wild type and Dlx mutant mice. 1) Generate E10.5 mouse embryos that are either wild type, Dlx2-/-, Dlx1/2 -/- or Dlx5/6 -/-. 2) Determine genotype by PCR. 3) Dissect branchial arches from the different genotypes. 4) Separate maxillary and mandibular branch of each branchial arch. 5) Prepare total RNA from the specimens. Obtain sufficient tissue to obtain 10 ug of total RNA - based on previous experience we anticipate that this will require ~ 10 branchial arches. We will pool the tissue from different embryos of the same genotype. 6) Send total RNA to TGEN for probe preparation, hybridization and array result analysis. Keywords: other
Project description:Distinct shaping of the upper versus lower facial skeleton is essential for function of the vertebrate jaw and middle ear, yet the cellular mechanisms by which this occurs have remained unclear. Here, we show that Endothelin1 (Edn1) signaling accelerates mesenchymal condensation and subsequent cartilage formation in the lower face through antagonism of Jagged-Notch signaling and Prrx1 transcription factors. A genomic analysis of facial skeletal precursors in mutants and overexpression embryos reveals that Jagged-Notch signaling represses genes that are strongly induced as pharyngeal arch neural crest-derived cells begin skeletal differentiation. In wild types, initial Jagged-Notch repression dorsally ensures that barx1+ condensations and cartilage differentiation occur first in ventral-intermediate zones of the pharyngeal arches. Reduced Jagged-Notch signaling results in an expansion of pre-cartilage condensations in the upper face, with loss of barx1 partially restoring dorsal cartilage shapes in jag1b mutants. Further, by studying new mutants for zebrafish prrx1a and prrx1b, we find that Prrx1 genes function in parallel to Jagged-Notch signaling to restrict the formation of dorsal barx1+ pre-cartilage condensations. Consistently, combined losses of jag1b and prrx1a/b robustly rescue ventral barx1+ condensations and lower facial cartilage development in edn1 mutants. Together, our work suggests that Edn1 works through parallel inhibition of Jagged-Notch and Prrx1 pathways to promote an earlier and more extensive establishment of cartilage condensations in the lower face.
Project description:Enhancer-promoter interactions preferentially occur within boundary-insulated topologically associating domains (TADs), limiting inter-TAD interactions. Enhancer clusters in linear proximity, termed super-enhancers (SEs), ensure high target gene expression levels. Little is known about SE topological regulatory impact during craniofacial development. Here, we identified 2232 genome-wide putative SEs in mouse cranial neural crest cells (CNCCs), 147 of which target genes establishing CNCC positional identity during face formation. In second pharyngeal arch (PA2) CNCCs, a multiple SE-containing region, partitioned into Hoxa Inter-TAD Regulatory Element 1 and 2 (HIRE1 and HIRE2), establishes long-range inter-TAD interactions selectively with Hoxa2, that is required for external and middle ear structures. HIRE2 deletion in a Hoxa2 haploinsufficient background results in microtia. HIRE1 deletion phenocopies the full homeotic Hoxa2 knockout phenotype and induces PA3 and PA4 CNCC abnormalities correlating with Hoxa2 and Hoxa3 transcriptional downregulation. Thus, SEs can overcome TAD insulation and regulate anterior Hoxa gene collinear expression in a CNCC subpopulation-specific manner during craniofacial development.
Project description:Enhancer-promoter interactions preferentially occur within boundary-insulated topologically associating domains (TADs), limiting inter-TAD interactions. Enhancer clusters in linear proximity, termed super-enhancers (SEs), ensure high target gene expression levels. Little is known about SE topological regulatory impact during craniofacial development. Here, we identified 2232 genome-wide putative SEs in mouse cranial neural crest cells (CNCCs), 147 of which target genes establishing CNCC positional identity during face formation. In second pharyngeal arch (PA2) CNCCs, a multiple SE-containing region, partitioned into Hoxa Inter-TAD Regulatory Element 1 and 2 (HIRE1 and HIRE2), establishes long-range inter-TAD interactions selectively with Hoxa2, that is required for external and middle ear structures. HIRE2 deletion in a Hoxa2 haploinsufficient background results in microtia. HIRE1 deletion phenocopies the full homeotic Hoxa2 knockout phenotype and induces PA3 and PA4 CNCC abnormalities correlating with Hoxa2 and Hoxa3 transcriptional downregulation. Thus, SEs can overcome TAD insulation and regulate anterior Hoxa gene collinear expression in a CNCC subpopulation-specific manner during craniofacial development.
Project description:Enhancer-promoter interactions preferentially occur within boundary-insulated topologically associating domains (TADs), limiting inter-TAD interactions. Enhancer clusters in linear proximity, termed super-enhancers (SEs), ensure high target gene expression levels. Little is known about SE topological regulatory impact during craniofacial development. Here, we identified 2232 genome-wide putative SEs in mouse cranial neural crest cells (CNCCs), 147 of which target genes establishing CNCC positional identity during face formation. In second pharyngeal arch (PA2) CNCCs, a multiple SE-containing region, partitioned into Hoxa Inter-TAD Regulatory Element 1 and 2 (HIRE1 and HIRE2), establishes long-range inter-TAD interactions selectively with Hoxa2, that is required for external and middle ear structures. HIRE2 deletion in a Hoxa2 haploinsufficient background results in microtia. HIRE1 deletion phenocopies the full homeotic Hoxa2 knockout phenotype and induces PA3 and PA4 CNCC abnormalities correlating with Hoxa2 and Hoxa3 transcriptional downregulation. Thus, SEs can overcome TAD insulation and regulate anterior Hoxa gene collinear expression in a CNCC subpopulation-specific manner during craniofacial development.
Project description:Enhancer-promoter interactions preferentially occur within boundary-insulated topologically associating domains (TADs), limiting inter-TAD interactions. Enhancer clusters in linear proximity, termed super-enhancers (SEs), ensure high target gene expression levels. Little is known about SE topological regulatory impact during craniofacial development. Here, we identified 2232 genome-wide putative SEs in mouse cranial neural crest cells (CNCCs), 147 of which target genes establishing CNCC positional identity during face formation. In second pharyngeal arch (PA2) CNCCs, a multiple SE-containing region, partitioned into Hoxa Inter-TAD Regulatory Element 1 and 2 (HIRE1 and HIRE2), establishes long-range inter-TAD interactions selectively with Hoxa2, that is required for external and middle ear structures. HIRE2 deletion in a Hoxa2 haploinsufficient background results in microtia. HIRE1 deletion phenocopies the full homeotic Hoxa2 knockout phenotype and induces PA3 and PA4 CNCC abnormalities correlating with Hoxa2 and Hoxa3 transcriptional downregulation. Thus, SEs can overcome TAD insulation and regulate anterior Hoxa gene collinear expression in a CNCC subpopulation-specific manner during craniofacial development.
Project description:Enhancer-promoter interactions preferentially occur within boundary-insulated topologically associating domains (TADs), limiting inter-TAD interactions. Enhancer clusters in linear proximity, termed super-enhancers (SEs), ensure high target gene expression levels. Little is known about SE topological regulatory impact during craniofacial development. Here, we identified 2232 genome-wide putative SEs in mouse cranial neural crest cells (CNCCs), 147 of which target genes establishing CNCC positional identity during face formation. In second pharyngeal arch (PA2) CNCCs, a multiple SE-containing region, partitioned into Hoxa Inter-TAD Regulatory Element 1 and 2 (HIRE1 and HIRE2), establishes long-range inter-TAD interactions selectively with Hoxa2, that is required for external and middle ear structures. HIRE2 deletion in a Hoxa2 haploinsufficient background results in microtia. HIRE1 deletion phenocopies the full homeotic Hoxa2 knockout phenotype and induces PA3 and PA4 CNCC abnormalities correlating with Hoxa2 and Hoxa3 transcriptional downregulation. Thus, SEs can overcome TAD insulation and regulate anterior Hoxa gene collinear expression in a CNCC subpopulation-specific manner during craniofacial development.