Project description:Retinoblastoma gene (Rb1) is required for proper cell cycle exit in the developing mouse inner ear and its deletion in the embryo leads to proliferation of sensory progenitor cells that differentiate into hair cells and supporting cells. In the Pou4f3-Cre:Rb1 flox/flox (Rb1 cKO) inner ear, utricular hair cells differentiate and survive into adulthood whereas differentiation and survival of cochlear hair cells are impaired. To comprehensively survey the pRb pathway in the mammalian inner ear, we performed microarray analysis of Rb1 cKO cochlea and utricle. P6 or 2-month control and Rb1 cKO littermates were euthanized and the inner ear tissues were dissected. Total RNA was extracted from the pooled samples. Technical duplicates of the pooled RNA were used for microarray.
Project description:To determine the mechanism through which PD0325901(PD) promotes inner ear hair cells generation, we cultured the inner ear organoids in 1 μM PD or the same volume of DMSO for 10 days, after which we used RNA-seq to establish a database to analyze differentially expressed genes .
Project description:Single-cell proteomics can reveal the changing protein composition of differentiating cells. We used shotgun mass spectrometry to determine the abundant proteins present in single or small pools of subpicoliter-sized cells from the embryonic day 15 (E15) utricle of the chicken inner ear, when many hair cells are differentiating from progenitor (supporting) cells. The actin monomer binding protein thymosin β4 (TMSB4X) was present in E15 progenitor cells at nearly equimolar levels relative to actin, but dropped to one-tenth that value in hair cells, with little change in total actin. Single-cell RNA-seq analysis of E15 utricle cells showed that TMSB4X transcripts fell in abundance once hair-cell differentiation initiated. These results suggest that most actin is sequestered in progenitor cells, but upon differentiation to hair cells, actin is released, permitting assembly of the sensory hair bundle.
Project description:Retinoblastoma gene (Rb1) is required for proper cell cycle exit in the developing mouse inner ear and its deletion in the embryo leads to proliferation of sensory progenitor cells that differentiate into hair cells and supporting cells. In the Pou4f3-Cre:Rb1 flox/flox (Rb1 cKO) inner ear, utricular hair cells differentiate and survive into adulthood whereas differentiation and survival of cochlear hair cells are impaired. To comprehensively survey the pRb pathway in the mammalian inner ear, we performed microarray analysis of Rb1 cKO cochlea and utricle.
Project description:Hair cells of the inner ear are essential for hearing and balance. As a consequence, pathogenic variants in genes specifically expressed in hair cells often cause hereditary deafness. Hair cells are few in number and not easily isolated from the adjacent supporting cells, so the biochemistry and molecular biology of hair cells can be difficult to study. To study gene expression in hair cells, we developed a protocol for hair cell isolation by FACS sorting. With nearly pure hair cells and surrounding cells, from cochlea and utricle and from embryonic day 16 to postnatal day 7, we performed a comprehensive cell-type-specific RNA-Seq study of gene expression during mouse inner ear development. Expression profiling revealed new hair-cell genes with distinct expression patterns: some are specific for vestibular hair cells, others for cochlear hair cells, and some are expressed just before or after maturation of mechanosensitivity. We found that many of the known hereditary deafness genes are much more highly expressed in hair cells than surrounding cells, suggesting that genes preferentially expressed in hair cells are good candidates for unknown deafness genes.
Project description:A major cause of human deafness and vestibular dysfunction is permanent loss of the mechanosensory hair cells of the inner ear. In non-mammalian vertebrates such as zebrafish, regeneration of missing hair cells can occur throughout life. While a comparative approach has the potential to reveal the basis of such differential regenerative ability, the degree to which the inner ears of fish and mammals share common hair and supporting cell types remains unresolved. Here we perform single-cell RNA sequencing of the zebrafish inner ear at embryonic through adult stages to catalog the diversity of hair and non-sensory supporting cells. We identify a putative progenitor population for hair and supporting cells, as well as distinct hair and supporting cell types in the maculae versus cristae. The hair and supporting cell types differ from those described for the lateral line, a distributed mechanosensory organ in zebrafish in which most studies of hair cell regeneration have been conducted. In the maculae, we identify two subtypes of hair cells that share gene expression with mammalian striolar or extrastriolar hair cells. In situ hybridization reveals that these hair cell subtypes occupy distinct spatial domains within the two major macular organs, the utricle and saccule, consistent with the reported distinct electrophysiological properties of hair cells within these domains. These findings suggest that primitive specialization of spatially distinct striolar and extrastriolar hair cells likely arose in the last common ancestor of fish and mammals. The similarities of inner ear cell type composition between fish and mammals also support using zebrafish as a relevant model for understanding inner ear-specific hair cell function and regeneration.