4C-seq analysis of three-dimensional chromatin interactions at the mouse Shox2 locus during embryonic limb development
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ABSTRACT: The SHOX2 transcription factor is required during mouse embryonic development for the formation of the proximal elements of limbs, the humerus and femur. The Shox2 gene is flanked by an extensive gene desert spanning over 500 kilobases (kb) that contains many evolutionarily conserved elements with predicted cis-regulatory activities. However, the transcriptional enhancer potential of the vast majority of these regions have not yet been assessed. Therefore, we have generated a map of the Shox2 regulatory landscape during limb development using chromosome conformation capture techniques (4C-Seq). We report that at least five enhancers, distributed over more than 500 kb interact with the Shox2 gene and control its expression in developing proximal limbs, as confirmed by transgenic mouse assays. Furthermore, by using two of the identified enhancer candidates as 4C-seq viewpoints, we also find evidence that three of these putative enhancers interact with each other as well as the Shox2 gene, perhaps forming a cooperative regulatory complex. We expect this study to provide insight into the regulation of the human SHOX gene, a closely-related homolog of Shox2, that is similarly flanked by a large gene desert. Notably, deletions within the gene desert downstream of human SHOX are implicated as a major cause of the limb deformities characteristic of Léri-Weill dyschondrosteosis.
Project description:Deficiency of the human short stature homeobox-containing gene (SHOX) has been identified in several disorders characterized by reduced height and skeletal anomalies such as Turner, Leri-Weill and Langer syndrome as well as idiopathic short stature. Although highly conserved in vertebrates, rodents lack a SHOX orthologue. Here, we compared gene expression profiles of wildtype and SHOX transgenic mouse limbs using microarray experiments to identify SHOX target genes in the developing limb. Limbs of E12.5 mouse embryos were dissected, fore- and hindlimbs were pooled and genotyped for RNA extraction. RNA from 2 to 4 littermates was pooled per genotype (Wildtype and SHOX transgene) and compared. In total, 2 microarray hybridization experiments were performed using RNA from 2 biological replicate samples for each genotype.
Project description:Deficiency of the human short stature homeobox-containing gene (SHOX) has been identified in several disorders characterized by reduced height and skeletal anomalies such as Turner, Leri-Weill and Langer syndrome as well as idiopathic short stature. Although highly conserved in vertebrates, rodents lack a SHOX orthologue. Here, we compared gene expression profiles of wildtype and SHOX transgenic mouse limbs using microarray experiments to identify SHOX target genes in the developing limb.
Project description:The development of vertebrate extremities is a complex process which requires a highly coordinated network of different transcriptional activities. The homeodomain transcription factor Shox2 is a key player in limb formation controlling neural, muscular and skeletal development. Here, we compared gene expression profiles of wildtype and Shox2 knockout limbs using microarray experiments to identify Shox2 target genes. Limbs of E12.5 mouse embryos were dissected, fore- and hindlimbs were pooled and genotyped for RNA extraction. RNA from 3 embryos of 2 different pregnancies (in total 6 embryos) was pooled per genotype (Wildtype and Shox2 Knockout) and compared.
Project description:Gene deserts spanning more than 500kb of non-protein coding genomic sequence are considered evolutionarily ancient and stable and are enriched in the vicinity of developmental regulator genes (Ovcharenko 2005). These extensive genomic regions typically harbor numerous conserved elements with predicted gene regulatory potential pointing to critical tissue-specific functions during development. Nevertheless, the biological necessity and underlying funtional enhancer landscapes of most gene deserts near developmental transcription factors (TFs) remain unknown, and it is unclear how precise pleiotropic expression patterns emerge from gene desert sequence. Here, we investigated the cis-regulatory architecture and function of a gene desert flanking the mouse Shox2 transcriptional regulator which itself is essential for embryonic limb, craniofacial, and cardiac pacemaker development. By combining epigenomic enhancer prediction, transgenic reporter validation and region-specific chromatin capture (C-HiC), we define the embryonic in vivo enhancer landscape and chromatin topology of the Shox2 gene desert. Targeted and context-specific genomic deletions uncover the gene desert not only as a regulator of embryonic survival through enhancer-mediated control of cardiac Shox2 expression, but also link distinct subsets of tissue-specific gene desert enhancers to the regulation of craniofacial patterning and proximal limb development. Our results hence identify the Shox2 gene desert as a fundamental genomic unit indispensable for pleiotropic patterning, robust organ morphogenesis and embryonic development progression by serving as a dynamic hub for tissue-specific developmental enhancers.
Project description:Gene deserts spanning more than 500kb of non-protein coding genomic sequence are considered evolutionarily ancient and stable and are enriched in the vicinity of developmental regulator genes (Ovcharenko 2005). These extensive genomic regions typically harbor numerous conserved elements with predicted gene regulatory potential pointing to critical tissue-specific functions during development. Nevertheless, the biological necessity and underlying funtional enhancer landscapes of most gene deserts near developmental transcription factors (TFs) remain unknown, and it is unclear how precise pleiotropic expression patterns emerge from gene desert sequence. Here, we investigated the cis-regulatory architecture and function of a gene desert flanking the mouse Shox2 transcriptional regulator which itself is essential for embryonic limb, craniofacial, and cardiac pacemaker development. By combining epigenomic enhancer prediction, transgenic reporter validation and region-specific chromatin capture (C-HiC), we define the embryonic in vivo enhancer landscape and chromatin topology of the Shox2 gene desert. Targeted and context-specific genomic deletions uncover the gene desert not only as a regulator of embryonic survival through enhancer-mediated control of cardiac Shox2 expression, but also link distinct subsets of tissue-specific gene desert enhancers to the regulation of craniofacial patterning and proximal limb development. Our results hence identify the Shox2 gene desert as a fundamental genomic unit indispensable for pleiotropic patterning, robust organ morphogenesis and embryonic development progression by serving as a dynamic hub for tissue-specific developmental enhancers.
Project description:Gene deserts spanning more than 500kb of non-protein coding genomic sequence are considered evolutionarily ancient and stable and are enriched in the vicinity of developmental regulator genes (Ovcharenko 2005). These extensive genomic regions typically harbor numerous conserved elements with predicted gene regulatory potential pointing to critical tissue-specific functions during development. Nevertheless, the biological necessity and underlying funtional enhancer landscapes of most gene deserts near developmental transcription factors (TFs) remain unknown, and it is unclear how precise pleiotropic expression patterns emerge from gene desert sequence. Here, we investigated the cis-regulatory architecture and function of a gene desert flanking the mouse Shox2 transcriptional regulator which itself is essential for embryonic limb, craniofacial, and cardiac pacemaker development. By combining epigenomic enhancer prediction, transgenic reporter validation and region-specific chromatin capture (C-HiC), we define the embryonic in vivo enhancer landscape and chromatin topology of the Shox2 gene desert. Targeted and context-specific genomic deletions uncover the gene desert not only as a regulator of embryonic survival through enhancer-mediated control of cardiac Shox2 expression, but also link distinct subsets of tissue-specific gene desert enhancers to the regulation of craniofacial patterning and proximal limb development. Our results hence identify the Shox2 gene desert as a fundamental genomic unit indispensable for pleiotropic patterning, robust organ morphogenesis and embryonic development progression by serving as a dynamic hub for tissue-specific developmental enhancers.
Project description:Gene deserts spanning more than 500kb of non-protein coding genomic sequence are considered evolutionarily ancient and stable and are enriched in the vicinity of developmental regulator genes (Ovcharenko 2005). These extensive genomic regions typically harbor numerous conserved elements with predicted gene regulatory potential pointing to critical tissue-specific functions during development. Nevertheless, the biological necessity and underlying funtional enhancer landscapes of most gene deserts near developmental transcription factors (TFs) remain unknown, and it is unclear how precise pleiotropic expression patterns emerge from gene desert sequence. Here, we investigated the cis-regulatory architecture and function of a gene desert flanking the mouse Shox2 transcriptional regulator which itself is essential for embryonic limb, craniofacial, and cardiac pacemaker development. By combining epigenomic enhancer prediction, transgenic reporter validation and region-specific chromatin capture (C-HiC), we define the embryonic in vivo enhancer landscape and chromatin topology of the Shox2 gene desert. Targeted and context-specific genomic deletions uncover the gene desert not only as a regulator of embryonic survival through enhancer-mediated control of cardiac Shox2 expression, but also link distinct subsets of tissue-specific gene desert enhancers to the regulation of craniofacial patterning and proximal limb development. Our results hence identify the Shox2 gene desert as a fundamental genomic unit indispensable for pleiotropic patterning, robust organ morphogenesis and embryonic development progression by serving as a dynamic hub for tissue-specific developmental enhancers.
Project description:The development of vertebrate extremities is a complex process which requires a highly coordinated network of different transcriptional activities. The homeodomain transcription factor Shox2 is a key player in limb formation controlling neural, muscular and skeletal development. Here, we compared gene expression profiles of wildtype and Shox2 knockout limbs using microarray experiments to identify Shox2 target genes.
Project description:The development of vertebrate extremities is a complex process which requires a highly coordinated network of different transcriptional activities. The homeodomain transcription factor Shox2 is a key player in limb formation controlling neural, muscular and skeletal development. Here, we compared gene expression profiles of wildtype and Shox2 knockout limbs using microarray experiments to identify Shox2 target genes.
Project description:The development of vertebrate extremities is a complex process which requires a highly coordinated network of different transcriptional activities. The homeodomain transcription factor Shox2 is a key player in limb formation controlling neural, muscular and skeletal development. Here, we compared gene expression profiles of wildtype and Shox2 knockout limbs using microarray experiments to identify Shox2 target genes. Forelimbs of E11.5 mouse embryos were dissected and genotyped for RNA extraction. RNA from 3-4 embryos of 2 different pregnancies was used for hybridisation to 2 arrays per genotype (wildtype and Shox2 knockout) and compared.