Project description:An abundance of research has recently highlighted the susceptibility of cochleovestibular ganglion (CVG) neurons to noise damage and aging in the adult cochlea, resulting in hearing deficits. Furthering our understanding of the transcriptional cascades that contribute to CVG development may provide insight into how these cells can be regenerated to treat inner ear dysfunction. Here we perform a high-depth single-cell RNA sequencing analysis of the E10.5 otic vesicle and its surrounding tissues, including CVG precursor neuroblasts and emerging CVG neurons. Clustering and trajectory analysis of otic lineage cells reveals otic markers and the changes in gene expression that occur from neuroblast delamination towards the development of the CVG. This dataset provides a valuable resource for further identifying the mechanisms associated with CVG development from neurosensory competent cells within the otic vesicle.
Project description:An abundance of research has recently highlighted the susceptibility of cochleovestibular ganglion (CVG) neurons to noise damage and aging in the adult cochlea, resulting in hearing deficits. Furthering our understanding of the transcriptional cascades that contribute to CVG development may provide insight into how these cells can be regenerated to treat inner ear dysfunction. Here we perform a high-depth single-cell RNA sequencing analysis of the E10.5 otic vesicle and its surrounding tissues, including CVG precursor neuroblasts and emerging CVG neurons. Clustering and trajectory analysis of otic-lineage cells reveals otic markers and the changes in gene expression that occur from neuroblast delamination toward the development of the CVG. This dataset provides a valuable resource for further identifying the mechanisms associated with CVG development from neurosensory competent cells within the otic vesicle.
Project description:Several transcription factors are known to be expressed in discrete regions of the otic vesicle and Dlx5 is one of those that is expressed highly in the presumptive dorsal vestibular region. Mice lacking Dlx5 have vestibular defects. Specifically, they fail to form the endolymphatic duct (a defect visible as early as E10) as well as the anterior and posterior semi-circular canals. The lateral canal does form but is smaller, whereas the saccule, the utricle and the cochlea appear relatively normal. The goal of this study was to use microarrays to identify differentially expressed genes between wild-type and Dlx5-null otic vesicles microdissected from E10 and 10.5 and identify downstream targets of Dlx5 by searching the immediate 3kb promoter regions of the differentially expressed genes for homeodomain binding sites followed by chromatin immunoprecipitation in an otic vesicle-derived cell line over-expressing Dlx5. Normal vestibular morphogenesis is compromised in mice lacking Dlx5, a member of the Distal-less family of homeobox transcription factors. We identified its direct downstream targets in the developing mouse inner ear by gene expression profiling wild-type and Dlx5 null otic vesicles from embryonic stages E10 and E10.5. Four hundred genes were differentially expressed in mutants when compared to wild-type in at least one of the two stages. To further constrain the list of likely direct targets of Dlx5, we examined the genomic DNA sequences in the 3kb promoter regions immediately proximal to the transcriptional start sites of these genes. We searched for (i) one or more previously described binding site for Dlx5, (ii) one or more novel 12bp-long motifs with a canonical homeodomain response element (HDRE) shared by promoters of two or more genes, and (iii) 100% conservation of the 12bp-long HDRE-containing motifs in promoter regions of human orthologs. Forty genes passed one or more of these filters, 12 of which are known to be expressed in the developing otic vesicle in domains that at least partially overlap with that of Dlx5 in one or both stages that we examined. Chromatin immunoprecipitation using a Dlx5 antibody confirmed direct binding of Dlx5 to promoter regions of seven of these genes (Atbf1, Bmper, Large, Lrrtm1, and Msx1, all of which were down-regulated in mutants, and Ebf1 and Lhx1, both of which were up-regulated in mutants) in an otic vesicle-derived cell line over-expressing Dlx5. Gene expression profiling of this cell line showed that Bmper and Lrrtm1 transcripts were up-regulated, further supporting their identification as direct targets of Dlx5 activity. Otic vesicles from wild-type and Dlx5-null embryos were microdissected from mouse developmental stages E10 and E10.5 and expression profiled in duplicate for each stage and genotype. Dlx5-transfected and empty vector-transfected 2B1 cell line samples were also profiled in duplicate (independent cell cultures).
Project description:Several transcription factors are known to be expressed in discrete regions of the otic vesicle and Dlx5 is one of those that is expressed highly in the presumptive dorsal vestibular region. Mice lacking Dlx5 have vestibular defects. Specifically, they fail to form the endolymphatic duct (a defect visible as early as E10) as well as the anterior and posterior semi-circular canals. The lateral canal does form but is smaller, whereas the saccule, the utricle and the cochlea appear relatively normal. The goal of this study was to use microarrays to identify differentially expressed genes between wild-type and Dlx5-null otic vesicles microdissected from E10 and 10.5 and identify downstream targets of Dlx5 by searching the immediate 3kb promoter regions of the differentially expressed genes for homeodomain binding sites followed by chromatin immunoprecipitation in an otic vesicle-derived cell line over-expressing Dlx5. Normal vestibular morphogenesis is compromised in mice lacking Dlx5, a member of the Distal-less family of homeobox transcription factors. We identified its direct downstream targets in the developing mouse inner ear by gene expression profiling wild-type and Dlx5 null otic vesicles from embryonic stages E10 and E10.5. Four hundred genes were differentially expressed in mutants when compared to wild-type in at least one of the two stages. To further constrain the list of likely direct targets of Dlx5, we examined the genomic DNA sequences in the 3kb promoter regions immediately proximal to the transcriptional start sites of these genes. We searched for (i) one or more previously described binding site for Dlx5, (ii) one or more novel 12bp-long motifs with a canonical homeodomain response element (HDRE) shared by promoters of two or more genes, and (iii) 100% conservation of the 12bp-long HDRE-containing motifs in promoter regions of human orthologs. Forty genes passed one or more of these filters, 12 of which are known to be expressed in the developing otic vesicle in domains that at least partially overlap with that of Dlx5 in one or both stages that we examined. Chromatin immunoprecipitation using a Dlx5 antibody confirmed direct binding of Dlx5 to promoter regions of seven of these genes (Atbf1, Bmper, Large, Lrrtm1, and Msx1, all of which were down-regulated in mutants, and Ebf1 and Lhx1, both of which were up-regulated in mutants) in an otic vesicle-derived cell line over-expressing Dlx5. Gene expression profiling of this cell line showed that Bmper and Lrrtm1 transcripts were up-regulated, further supporting their identification as direct targets of Dlx5 activity.
Project description:The morphogenesis of the otic vesicle (OV) to form inner ear organs serves as an excellent model system to understand cell fate acquisition on a single cell level. Tbx2 and Tbx3 (Tbx2/3) encode closely related T-box transcription factors that are expressed widely in the mammalian otic vesicle (OV). Inactivation of both genes in the Pax2-Cre lineage (Tbx2/3cKO) results in failed morphogenesis of the OV into inner ear organs. To understand the basis of these defects, single cell RNA-sequencing (scRNA-seq) was performed on the OV lineage using Pax2-Cre, in controls versus Tbx2/3cKO embryos, at stage E10.5. We identified a multipotent population termed otic progenitors that are localized to the anterior ventrolateral region of the OV in controls and are marked by expression of Fgf18, Sox3, and Cxcl12. The otic progenitor population was increased three-fold in Tbx2/3cKO embryos, concomitant with dysregulation of genes in these cells as well as reduced progression to more differentiated states of prosensory and nonsensory cells. An ectopic neural population of cells was detected in the posterior OV of Tbx2/3cKO embryos due to increased expression of Neurog1 and NeuroD1 but with reduced maturation. As all three cell fates were affected in Tbx2/3cKO embryos, we suggest that Tbx2/3 promotes progression of multipotent otic progenitors to more differentiated cell types in the OV.
Project description:Inner ear vestibular and spiral ganglion neurons (VGNs and SGNs) are known to play pivotal roles in balance control and sound detection. However, the molecular mechanisms underlying otic neurogenesis at early embryonic ages have remained unclear. Here, we use single-cell RNA-sequencing to reveal the transcriptomes of mouse otic tissues at three embryonic ages, embryonic day 9.5 (E9.5), E11.5, and E13.5, covering proliferating and undifferentiated otic neuroblasts and differentiating VGNs and SGNs. We validate the high quality of our studies by using multiple assays, including genetic fate-mapping analysis, and we uncover several previously unknown genes upregulated in neuroblasts or differentiating VGNs and SGNs, such as Shox2, Myt1, Casz1, and Sall3. Notably, our findings suggest a general cascaded differentiation trajectory during early otic neurogenesis. The comprehensive understanding of early otic neurogenesis provided by our study holds critical implications for both basic and translational research.
Project description:The T-box transcription factor Tbx1 is expressed in the otic vesicle and surrounding periotic mesenchyme during inner ear development. Mesenchymal Tbx1 is essential for inner ear development, with conditional mutants displaying defects in both auditory and vestibular systems. We have previously identified reduced expression of retinoic acid metabolic genes in the periotic mesenchyme of mesoderm conditional Tbx1 mutants, using the T-Cre mouse line, implicating retinoic acid in mesenchymal-epithelial signaling downstream of Tbx1 in the periotic mesenchyme. In order to identify downstream effectors of mesenchymal-epithelial signaling downstream of mesenchymal Tbx1, we have utilized a gene profiling approach comparing embryonic day 11.5 otic vesicle tissue from T-Cre-mediated conditional Tbx1 mutants (Mest-KO) and conditional heterozygous control litter mates (control). E11.5 T-Cre-mediated conditional Tbx1 mutants (Mest-KO) and control (T-Cre conditional Tbx1 heterozygotes) embryos were microdissected to isolate the otic vesicle. Left and right ears from 3 embryos of the same genotype were pooled for each chip.
Project description:The T-box transcription factor Tbx1 is expressed in the otic vesicle and surrounding periotic mesenchyme during inner ear development. Mesenchymal Tbx1 is essential for inner ear development, with conditional mutants displaying defects in both auditory and vestibular systems. We have previously identified reduced expression of retinoic acid metabolic genes in the periotic mesenchyme of mesoderm conditional Tbx1 mutants, using the T-Cre mouse line, implicating retinoic acid in mesenchymal-epithelial signaling downstream of Tbx1 in the periotic mesenchyme. In order to identify downstream effectors of mesenchymal-epithelial signaling downstream of mesenchymal Tbx1, we have utilized a gene profiling approach comparing embryonic day 11.5 otic vesicle and surrounding periotic mesenchyme from T-Cre-mediated conditional Tbx1 mutants (Mest-KO) and conditional heterozygous control litter mates (control). This data was used in conjunction with OV-only data (GSE34064) to identify expression changes within the periotic mesenchyme. E11.5 T-Cre-mediated conditional Tbx1 mutants (Mest-KO) and control (T-Cre conditional Tbx1 heterozygotes) embryos were microdissected to isolate the otic vesicle and surrounding periotic mesenchyme. Left and right ears from 3 embryos of the same genotype were pooled for each chip, and 3 biological replicates of each chip were performed.
Project description:The T-box transcription factor Tbx1 is expressed in the otic vesicle and surrounding periotic mesenchyme during inner ear development. Mesenchymal Tbx1 is essential for inner ear development, with conditional mutants displaying defects in both auditory and vestibular systems. We have previously identified reduced expression of retinoic acid metabolic genes in the periotic mesenchyme of mesoderm conditional Tbx1 mutants, using the T-Cre mouse line, implicating retinoic acid in mesenchymal-epithelial signaling downstream of Tbx1 in the periotic mesenchyme. In order to identify downstream effectors of mesenchymal-epithelial signaling downstream of mesenchymal Tbx1, we have utilized a gene profiling approach comparing embryonic day 11.5 otic vesicle tissue from T-Cre-mediated conditional Tbx1 mutants (Mest-KO) and conditional heterozygous control litter mates (control).