Transcriptome-wide comparison of the impact of Atoh1 and miR-183 family on pluripotent stem cells and multipotent otic progenitors
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ABSTRACT: Hair cells (HCs) are the mechanoreceptors responsible for hearing and balance in the inner ear. Multiple factors cause HC loss including aging, noise exposure and genetic predisposition. A barrier to hearing restoration after HC loss is the inability of mammalian auditory HCs to spontaneously regenerate. Multiple factors are shown to be crucial for HC development and represent good candidates for regenerative studies. Atoh1 is widely accepted to be necessary and contextually sufficient for driving HC fate. Furthermore, the miRNA-183 family is known to be expressed at the time of HC differentiation, and mutations in miR-96 (one member of the family) can cause deafness both in mouse and human. Our goal is to identify and compare the impact of Atoh1/miR-183 family alone and in combination on the transcriptome of two different developmental cell models; mouse embryonic stem cells (mESCs) and immortalized multipotent otic progenitors (iMOPs)
Project description:Mammalian cochlea hair cells can be regenerated from the adjacent supporting cells in many ways, however, the newly hair cells are immature and without hearing function almost. The expression of Atoh1 is an important maker of the appearance of newly hair cells, many approaches of inner ear hair cells’ regeneration are concerned with the transcription factor Atoh1. However, most new HCs are immature HCs, and they do not have the function of mature HCs and eventually die a few weeks after regeneration. Thus promoting the maturation and survival of new HCs is the primary focus of HC regeneration field. We used RNA-Seq analysis to compare the differences between the transcriptomes of Atoh1 overexpression-induced new HCs and the original HCs, and to define the factors that might help to promote the maturation and survival of new HCs.
Project description:Mechanosensory hair cells (HCs) are the primary receptors of our senses of hearing and balance. However, very little is known about the transcriptional regulators involved in HC fate determination and differentiation. In this paper, we show that expression of three HC lineage-specific transcription factors: Gfi1, Pou4f3 and Atoh1, can induce a direct commitment towards HC fate during in vitro embryonic stem cell (ESC) differentiation. Induced HCs (iHCs) express numerous HC-specific genes and exhibit polarized membrane protusions reminiscent of stereociliary bundles. The ability to obtain purified populations of iHCs by virtue of the Myo7:mVenus reporter line (iGPA-Myo7a:mVenus) allowed us to generate highly reproducible gene expression profiles for these cells, at various phases of their development (day 8 and day 12 of cell culture).
Project description:Cochlear hair cells (HCs) in the inner ear are responsible for sound detection. For HC fate specification, the master transcription factor Atoh1 is both necessary and sufficient. Atoh1 expression is dynamic and tightly regulated during development, but the cis-regulatory elements mediating this regulation remain unresolved. Unexpectedly, we found that deleting the only recognized Atoh1 enhancer, defined here as Eh1, failed to impair HC development. By using ATAC-seq (assay for transposase-accessible chromatin with high-throughput sequencing), we discovered two additional Atoh1 enhancers: Eh2 and Eh3. Notably, Eh2 deletion was sufficient for impairing HC development, and concurrent deletion of Eh1 and Eh2 or all three enhancers resulted in nearly complete absence of HCs. Lastly, we showed that Atoh1 binds to all three enhancers, consistent with its autoregulatory function. Our findings reveal that the cooperative action of three distinct enhancers underpins effective Atoh1 regulation during HC development, indicating potential therapeutic approaches for HC regeneration.
Project description:Cochlear hair cells (HCs) in the inner ear are responsible for sound detection. For HC fate specification, the master transcription factor Atoh1 is both necessary and sufficient. Atoh1 expression is dynamic and tightly regulated during development, but the cis-regulatory elements mediating this regulation remain unresolved. Unexpectedly, we found that deleting the only recognized Atoh1 enhancer, defined here as Eh1, failed to impair HC development. By using ATAC-seq (assay for transposase-accessible chromatin with high-throughput sequencing), we discovered two additional Atoh1 enhancers: Eh2 and Eh3. Notably, Eh2 deletion was sufficient for impairing HC development, and concurrent deletion of Eh1 and Eh2 or all three enhancers resulted in nearly complete absence of HCs. Lastly, we showed that Atoh1 binds to all three enhancers, consistent with its autoregulatory function. Our findings reveal that the cooperative action of three distinct enhancers underpins effective Atoh1 regulation during HC development, indicating potential therapeutic approaches for HC regeneration.
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 and HC regeneration, 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 compared gene expression profiles between Atoh1 activation vs. MYC/NICD/Atoh1 co-activation.
Project description:Ectopic expression of Atoh1 in non-sensory supporting cells (SCs) in mouse cochleae induces their conversion to hair cells (HCs) in vivo. cHCs in multiple intermediate states of the conversion process that most closely resembled neonatal differentiating HCs, but differed from the progenitors. We further identified 52 transcription factors that are differentially expressed in cHCs, SCs, and mature HCs and confirmed that Isl1 synergistically enhanced the efficiency of Atoh1-mediated HC conversion in cochlear explants. Our results demonstrate that direct HC conversion from SCs in vivo follows a different path from normal development and requires multiple factors for maximum efficiency and completion.
Project description:Mutations in miRNA-96, a microRNA expressed within the hair cells (HCs) of the inner ear, result in progressive hearing loss in both mouse models and humans. While previous studies have delved into miR-96 transcriptional cascades via whole organ of Corti microarray experiments of diminuendo (Mir96Dmdo) mice, they face limitations in pinpointing cell type-specific differentially expressed genes. This hinders the ability to conclusively determine if the effects of Mir96Dmdo are specifically within HCs and contribute to the observed abnormal Mir96Dmdo HC phenotype and determine the role of miR-96 in HCs. In this study, we generate the first HC-specific RNA-sequencing (RNA-seq) datasets from Mir96Dmdo; Atoh1/nGFP+ postnatal day 1 wildtype, heterozygous, and homozygous mutant mice. Our differential gene expression analysis between Mir96Dmdo homozygous mutant HCs compared to wildtype HCs identified 215 upregulated and 428 downregulated genes. Many significantly downregulated genes in Mir96Dmdo homozygous mutant HCs have established roles in HC development and/or known roles in deafness such as Myo15, Myo7a, Ush1c Gfi1, and Ptprq, some of which were not previously identified in other miR-96 datasets. In addition, active modules of protein-protein interaction networks of significantly downregulated genes in Mir96Dmdo homozygous mutant HCs reveal enrichment in GO terms with biological functions such as sound perception and endocytosis. Genes significantly upregulated in Mir96Dmdo homozygous mutant HCs, which are more likely to be direct targets of miR-96, show higher expression in wildtype supporting cells compared to wildtype HCs, suggesting a role of miR-96 in suppressing non-HC genes during HC development. Finally, all generated HC-specific Mir96Dmdo RNA-seq datasets from this manuscript are now publicly available in the miR-96 specific gEAR profile (https://umgear.org/p?l=miR96).
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.
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. We identified a combination (the cocktail) of drug-like molecules composing of small molecules and siRNAs to activate the pathways of Myc, Notch1, Wnt and cAMP. To identify molecules to reprogram mature cochlear SCs and HC regeneration, we utilized single-cell RNA sequencing and uncovered the pathways and their target genes underlying chemical-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, in response to chemical-induced reprogramming. We compared gene expression profiles between Vehicle/ad.Atoh1 activation vs. Cocktail (chemical reprogramming)/ad.Atoh1 activation.
Project description:MYCN and HDAC2 jointly repress the transcription of tumor suppressive micro RNA miR-183 in neuroblastoma. Enforced miR-183 expression induces neuroblastoma cell death and inhibits anchorage-independent colony formation and subcutaneous xenograft growth in mice. We here aimed to unravel the miR-183 signaling network and elucidated the role of MYCN mediated transcriptional activation of members of the minichromosome maintenance (MCM) family protein family involving miR-183 . The hexamer protein complex formed by MCM proteins is involved in the initiation and elongation of eukaryotic genome replication, thereby contributing to genomic integrity. Analysis of miR-183 versus negative control transfected neuroblastoma cells identified 85 differentially expressed proteins in a label-free mass spectrometric approach. Six members of the MCM family were found to be lower expressed upon enforced miR-183 expression, and subsequent annotation category enrichment analysis revealed a 14-fold enrichment in the protein module category “MCM”. Down-regulation was confirmed by western blot analysis. MicroRNA target prediction software studies revealed that miR-183 was predicted to directly target several MCMs.