Project description:Inner ear cochlear supporting cells (SCs) are highly specialized glia-like cells that structurally and functionally support neighboring mechano-sensory hair cells. Despite their importance for proper auditory function, little is known about the molecular mechanisms that control their development. In this study we investigated the function of the Notch ligand Jagged1 (Jag1) in cochlear SC differentiation and maintenance. To address the function of Jag1 in the differentiation of SCs, we conditionally deleted Jag1 in stage E14.5 SC precursors using the recently established Sox2-CreER/+ and Jag1 fx/fx mouse lines. Analysis of stage P0 Jag1 mutant and control animals revealed that Hensen cells, a highly specialized SC-subtype located at the lateral edge of the auditory sensory epithelium, failed to form in the absence of Jag1. Other SC-subtypes did form in the absence of Jag1, however, their morphology and cellular arrangement was abnormal and SC-subtype specific genes and genes associated with mitochondrial function and protein synthesis were significantly reduced, indicating global defects in SC differentiation and SC homeostasis.
Project description:This study examined transcripts that are enriched in neonatal mouse cochlear supporting cells at postnatal day 1 and postnatal day 6. Supporting cells were purified by FACS sorting for GFP fluorescence from the cochleas of transgenic mice in which a BAC including the LFng locus drives the expression of GFP. Two replicates of GFP+ supporting cells were compared with all other cochlear cell types that were GFP-. We performed this experiment at two different ages, postnatal day 1 and postnatal day 6. mRNA profiles of supporting cells (GFP+) and all other cochlear cell types (GFP-), two replicates each, at P1 and P6 mice were generated by deep sequencing using Illumna TruSeq.
Project description:This study examined transcripts that are enriched in neonatal mouse cochlear supporting cells at postnatal day 1 and postnatal day 6 after inhibition of the Notch signaling pathway. Cochleas from postnatal day 0 and postnatal day 5 were cultured for 24 hours in the gamma secretase inhibitor DAPT or DMSO as a vehicle control. Supporting cells were purified by FACS sorting for GFP fluorescence from the cochleas of transgenic mice in which a BAC including the LFng locus drives the expression of GFP. Two replicates of GFP+ supporting cells were compared with all other cochlear cell types that were GFP-. We performed this experiment at two different ages, postnatal day 0+24 hours culture and postnatal day 5 + 24 hours culture. (corresponding to P1 and P6). mRNA profiles of P0 and P5 supporting cells (GFP+) and all other cochlear cell types (GFP-) treated with DAPT or DMSO, two replicates each, were generated by deep sequencing using Illumna TruSeq.
Project description:This study examined transcripts that are enriched in neonatal mouse cochlear supporting cells at postnatal day 1 and postnatal day 6. Supporting cells were purified by FACS sorting for GFP fluorescence from the cochleas of transgenic mice in which a BAC including the LFng locus drives the expression of GFP. Two replicates of GFP+ supporting cells were compared with all other cochlear cell types that were GFP-. We performed this experiment at two different ages, postnatal day 1 and postnatal day 6.
Project description:This study examined transcripts that are enriched in neonatal mouse cochlear supporting cells at postnatal day 1 and postnatal day 6 after inhibition of the Notch signaling pathway. Cochleas from postnatal day 0 and postnatal day 5 were cultured for 24 hours in the gamma secretase inhibitor DAPT or DMSO as a vehicle control. Supporting cells were purified by FACS sorting for GFP fluorescence from the cochleas of transgenic mice in which a BAC including the LFng locus drives the expression of GFP. Two replicates of GFP+ supporting cells were compared with all other cochlear cell types that were GFP-. We performed this experiment at two different ages, postnatal day 0+24 hours culture and postnatal day 5 + 24 hours culture. (corresponding to P1 and P6).
Project description:Characterizing adult cochlear supporting cell transcriptional diversity using scRNA-Seq Hearing loss is a significant disability that impacts 432 million people worldwide. A significant proportion of these individuals are dissatisfied with or do not have access to available treatment options which include hearing aids and cochlear implants. An alternative approach to restore hearing would be to regenerate lost cells, including hair cells in the adult cochlea. Such therapy would require restoration of the organ of Corti’s complex architecture, necessitating regeneration of both mature hair cells and supporting cells. We characterize the first single-cell adult cochlear supporting cell transcriptomes with the goals of: (1) demonstrating their transcriptional distinctiveness from perinatal cochlear supporting cells, (2) providing a metric for future attempts at regenerating mature cochlear supporting cells by identifying both cell type-specific and regional-specific expression, and (3) identify cell cycle gene expression present in adult supporting cells at the single cell level which may establish a basis for targeting cell cycle regulation pathways to force these cells out of quiescence.
Project description:Mammalian cochlear outer hair cells (OHCs) are essential for hearing. Severe hearing impairment follows OHC degeneration. Previous attempts at regenerating new OHCs from cochlear supporting cells (SCs) have been unsuccessful, notably lacking expression of the key OHC motor protein, Prestin. Thus, regeneration of Prestin+ OHCs represented a barrier to restoring auditory function in vivo. Here, we reported the successful in vivo conversion of adult mouse cochlear SCs into Prestin+ OHC-like cells through the concurrent induction of two key transcriptional factors known to be necessary for OHC development: Atoh1 and Ikzf2. Single cell RNA sequencing reveals the upregulation of 729 OHC genes and downregulation of 331 SC genes in OHC-like cells. The resulting differentiation status of these OHC-like cells was much more advanced than previously achieved. This study thus established an efficient approach to induce the regeneration of Prestin+ OHCs, paving the way for in vivo cochlear repair via SC transdifferentiation.
Project description:Strategies to overcome irreversible cochlear hair cell (HC) damage and loss are of vital importance to develop a treatment for hearing loss. HC regeneration in adult cochlea relies on a two-phase process: 1) Reprogramming mature cochlear (SCs) to regain the properties of their younger selves; 2) Activating Atoh1, a gene responsible for HC fate-determining, in the reprogrammed adult SCs for HC regeneration. We have shown that, by transient co-activation of Myc and NICD (Notch1 intracellular domain), the adult mouse cochlea can be successfully reprogrammed to a relatively younger stage and regain progenitor capacity, with the regeneration of HCs following Atoh1 overexpression in vitro and in vivo. To identify molecules to reprogram mature cochlear SCs, we utilized single-cell RNA sequencing and uncovered the pathways and their target genes underlying MYC/NICD-mediated reprogramming. We used an in-house adult cochlea explant culture system and carried out single-cell RNA sequencing to examine the gene expression profiles of cochlear explants from a transgenic mouse model, rtTa/tet-Myc/-tet-NICD, in response to Dox-induced MYC/NICD co-activation. We have shown that a 4-day treatment by Dox in cultured adult rtTa/tetMyc/-tet-NICD cochleae was sufficient to reprogram adult SCs for HC regeneration.