Project description:Sphere-forming progenitor cells can be isolated from the fetal and adult mammalian inner ear and give rise to inner ear specific cell types in vitro. Here, we provide phenotypical and functional characterization of a new pool of auditory progenitors as sustainable source for sphere-derived auditory neurons. The so-called phoenix auditory neuroprogenitors, isolated from the A/J mouse spiral ganglion, exhibit nearly unlimited intrinsic self-renewal properties (beyond 40 passages). At any passage, phoenix spheres can be efficiently differentiated by withdrawing growth factors into mature spiral ganglion cells, expressing both neurons and glial cells phenotypic markers and exhibiting similar functional properties as mouse spiral ganglion explants and human sphere-derived spiral ganglion cells. The present dataset includes RNAseq-based transcriptome analysis of phoenix auditory neurons following 7 days of differentiation. mRNA levels in differentiated cells are expressed relatively to neuroprogenitor spheres of equivalent passage (paired samples at passage 12, 21 and 36)
Project description:The sense of hearing depends on the faithful transmission of sound information from the ear to the brain by spiral ganglion (SG) neurons. However, how SG neurons develop the connections and properties that underlie auditory processing is largely unknown. We catalogued gene expression in mouse SG neurons at six developmental stages, ranging from embryonic day 12 (E12), when SG neurons first extend projections, up until postnatal day 15 (P15), after the onset of hearing. For comparison, we also analyzed the closely-related vestibular ganglion (VG) at the same time points.
Project description:The sense of hearing depends on the faithful transmission of sound information from the ear to the brain by spiral ganglion (SG) neurons. However, how SG neurons develop the connections and properties that underlie auditory processing is largely unknown. We catalogued gene expression in mouse SG neurons at six developmental stages, ranging from embryonic day 12 (E12), when SG neurons first extend projections, up until postnatal day 15 (P15), after the onset of hearing. For comparison, we also analyzed the closely-related vestibular ganglion (VG) at the same time points. To identify genes involved in SG axon guidance and branching, target selection, synaptogenesis, synaptic refinement, and synaptic function, we collected SG at E12 and E13, E16, P0, P6, and P15. We also collected VG at the same time points. For E12 and E13 time points, SG and VG were microdissected from Rnx-cre; Z/EG embryos, which express GFP in the VG. E16-P15 VG was also isolated by microdissection from Rnx-cre; Z/EG animals. E16-P15 SG neurons were isolated by FACS sorting dissociated cochlea from Mafb-GFP animals.
Project description:Little is known about the timing and factors which regulate the specification of neuronal subtypes in the cochlear spiral ganglion. Here we collect Spiral Ganglion Neurons (SGNs) from the mouse across four developmental timepoints (E14, E16, E18 and P1) in order to transciptionally profile their development.
Project description:As the primary sensory neurons of the auditory system, Type I spiral ganglion neurons (SGNs) encode sound stimulus properties critical for the formation of auditory percept in higher brain areas. Their functional heterogeneity is thought to contribute to our ability to hear a wide range of sound intensities and against background noise, but how SGN diversity arises during development is poorly understood. Here we studied the role of the transcription factor Runx1 in establishing SGN heterogeneity in the mouse cochlea by single cell RNA-sequencing.
Project description:As the primary sensory neurons of the auditory system, Type I spiral ganglion neurons (SGNs) encode sound stimulus properties critical for the formation of auditory percept in higher brain areas. Their functional heterogeneity is thought to contribute to our ability to hear a wide range of sound intensities and against background noise, but how SGN diversity arises during development is poorly understood. Here we studied the role of the transcription factor Runx1 in establishing SGN heterogeneity in the mouse cochlea by single cell RNA-sequencing.
Project description:A cardinal feature of the auditory pathway is frequency selectivity represented in the form of a tonotopic map from the cochlea to the cortex. The molecular determinants of the auditory frequency map are unknown. Here, we discovered that the transcription factor ISL1 regulates features of auditory neurons, including the formation of the spiral ganglion neuron (SGN) and peripheral and central processes that shape the tonotopic representation of the auditory map. We selectively knocked out Isl1 in auditory neurons using Neurod1Cre strategies. In the absence of Isl1, SGNs migrate into the central cochlea and beyond. The cochlear wiring is profoundly reduced and disrupted. The central axons of Isl1 mutants lose their topographic projections and segregation at the cochlear nucleus. Transcriptome analysis of SGNs shows that Isl1 regulates neurogenesis, axonogenesis, migration, and the functional properties of neurons. Surprisingly, notable auditory processing features are preserved despite the significant hearing impairment, revealing central auditory pathway resilience and plasticity in mutant mice. Mutant mice demonstrate altered acoustic startle reflex, prepulse inhibition, characteristics of compensatory neural hyperactivity centrally. Our findings show that the Isl1 is one of the obligatory factors required to sculpt auditory structural and functional tonotopic maps. Still, upon Isl1 deletion, the ensuing compensatory plasticity of the auditory pathway does not suffice to overcome developmental changes at the peripheral sensory organ.
Project description:Spiral ganglion (SG) neurons of the cochlea convey all auditory inputs to the brain, yet the cellular and molecular complexity necessary to decode the various acoustic features in the SG has remained unresolved. Using unbiased single-cell RNA sequencing, we identified four types of SG neurons, including three novel subclasses of type I neurons and the type II neurons, and provide a comprehensive genetic framework that define their potential synaptic communication patterns. The connectivity patterns of the three subclasses of type I neurons with inner hair cells and their electrophysiological profiles suggest that they represent the intensity-coding properties of auditory afferents. Moreover, neuron type specification is already established at birth, indicating a neuronal diversification process independent of neuronal activity. Thus, this work provides a transcriptional catalog of neuron types in the cochlea, which serves as a valuable resource for dissecting cell-type-specific functions of dedicated afferents in auditory perception and in hearing disorders.
Project description:The spiral ganglion neurons (SGNs) of the cochlea are essential for auditory perception by transmitting complex auditory information from hair cells (HCs) to the brain, yet the molecular mechanisms generating their diversity are unknown. Here we used single cell RNA sequencing to reconstruct the developmental trajectories of SGN cell fates and identified genes and gene regulatory networks that participate to changes in developmental competence and cell states, and in specification of each major cell types. Our analysis also identified gene modules associated with the sequential binary decisions that delineate neuron fate choices along the diversification tree. Transcriptome analysis of both developing SGN and HC types further revealed cell-state specific cell-cell signaling potentially playing a role in the differentiation and connectivity profile of SGNs as well as human deafness-associated genes, both previously known and novel. Overall, our results identify molecular principles that shape SGN differentiation and will facilitate further studies of SGNs development, physiology and dysfunction.