Defects in the alternative splicing-dependent regulation of REST cause deafness - [mouse cultured organ of Corti].
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ABSTRACT: The DNA-binding protein REST forms complexes with histone deacetylases (HDACs) to repress neuronal genes in non-neuronal cells. In differentiating neurons, REST is downregulated predominantly by transcriptional silencing. Here we report that post-transcriptional inactivation of REST by alternative splicing is required for hearing in humans and mice. We show that in the mechanosensory hair cells of the mouse ear, regulated alternative splicing of a frameshift-causing exon into the Rest mRNA is essential for the derepression of many neuronal genes. Heterozygous deletion of this alternative exon of mouse Rest causes hair cell degeneration and deafness, and the HDAC inhibitor SAHA (Vorinostat) rescues the hearing of these mice. In humans, inhibition of the frameshifting splicing event by a novel REST variant is associated with dominantly inherited deafness. Our data reveal the necessity for alternative splicing-dependent regulation of REST in hair cells, and identify a potential treatment for a group of hereditary deafness cases.
Project description:The DNA-binding protein REST forms complexes with histone deacetylases (HDACs) to repress neuronal genes in non-neuronal cells. In differentiating neurons, REST is downregulated predominantly by transcriptional silencing. Here we report that post-transcriptional inactivation of REST by alternative splicing is required for hearing in humans and mice. We show that in the mechanosensory hair cells of the mouse ear, regulated alternative splicing of a frameshift-causing exon into the Rest mRNA is essential for the derepression of many neuronal genes. Heterozygous deletion of this alternative exon of mouse Rest causes hair cell degeneration and deafness, and the HDAC inhibitor SAHA (Vorinostat) rescues the hearing of these mice. In humans, inhibition of the frameshifting splicing event by a novel REST variant is associated with dominantly inherited deafness. Our data reveal the necessity for alternative splicing-dependent regulation of REST in hair cells, and identify a potential treatment for a group of hereditary deafness cases.
Project description:The DNA-binding protein REST forms complexes with histone deacetylases (HDACs) to repress neuronal genes in non-neuronal cells. In differentiating neurons, REST is downregulated predominantly by transcriptional silencing. Here we report that post-transcriptional inactivation of REST by alternative splicing is required for hearing in humans and mice. We show that in the mechanosensory hair cells of the mouse ear, regulated alternative splicing of a frameshift-causing exon into the Rest mRNA is essential for the derepression of many neuronal genes. Heterozygous deletion of this alternative exon of mouse Rest causes hair cell degeneration and deafness, and the HDAC inhibitor SAHA (Vorinostat) rescues the hearing of these mice. In humans, inhibition of the frameshifting splicing event by a novel REST variant is associated with dominantly inherited deafness. Our data reveal the necessity for alternative splicing-dependent regulation of REST in hair cells, and identify a potential treatment for a group of hereditary deafness cases.
Project description:The spontaneous mutant Bronx waltzer (bv) mouse line is characterized by deafness and balance defect. We located the bv mutation to the Srrm4 gene which encodes a regulator of alternative pre-mRNA splicing. We found that Srrm4 is expressed in balance and hearing organs (i.e. in the vestibular maculas and the cochlea). Srrm4 is also expressed in the central nervous system including the cerebellum. To identify potential splicing defects in bv/bv mice, we analyzed RNA samples from the vestibular maculas and cerebellums of bv/bv mice and control (bv/+) littermates, using mouse exon junction microarrays (MJAY). In this dataset, we include probe-set level data obtained from cerebellar samples. The processed data represent probe-set intensities that have been normalized to gene expression levels. 8 total samples were analyzed in this series: cerebellums from 4 heterozygous (bv/+) and 4 homozygous (bv/bv) mice at P15.
Project description:The spontaneous mutant Bronx waltzer (bv) mouse line is characterized by deafness and balance defect. We located the bv mutation to the Srrm4 gene which encodes a regulator of alternative pre-mRNA splicing. We found that Srrm4 is expressed in balance and hearing organs (i.e. in the vestibular maculas and the cochlea). Srrm4 is also expressed in the central nervous system including the cerebellum. To identify potential splicing defects in bv/bv mice, we analyzed RNA samples from the vestibular maculas and cerebellums of bv/bv mice and control (bv/+) littermates, using mouse exon junction microarrays (MJAY). In this dataset, we include probe-set level data obtained from cerebellar samples. The processed data represent probe-set intensities that have been normalized to gene expression levels.
Project description:Deafness is the most common form of sensory impairment in humans and frequently caused by defects in hair cells of the inner ear. Here we demonstrate that in a mouse model for recessive non-syndromic deafness (DFNB6), inactivation of Tmie in hair cells disrupts gene expression in the neurons that innervate them. This includes genes regulating axonal pathfinding and synaptogenesis, two processes that are disrupted in the inner ear of the mutant mice. Similar defects are observed in mouse models for deafness caused by mutations in other genes with primary functions in hair cells. Gene therapy targeting hair cells restores hearing and inner ear circuitry in DFNB6 model mice. We conclude that hair cell function is crucial for the establishment of peripheral auditory circuitry. Treatment modalities for deafness thus need to consider restoration of the function of both hair cells and neurons, even when the primary defect occurs in hair cells.
Project description:Mutations in GJB2 (Gap junction protein beta 2) are the most common genetic cause of non-syndromic hereditary deafness in humans, especially the 35delG and 235delC mutations. Owing to the homozygous-lethal of Gjb2 mutation in mice, there are currently no perfect mouse models carrying Gjb2 mutation to mimic human hereditary deafness and unveil the pathogenesis. Here, we first constructed heterozygous mutant mice, Gjb2+/35delG and Gjb2+/235delC, through androgenic haploid embryonic stem cells (AG-haESCs) mediated semi-cloning technology, which showed normal hearing function at P28. Furthermore, a homozygous mutant mouse model, Gjb235delG/35delG, was generated via enhanced tetraploid embryo complementation, which exhibited profound hearing loss like human patients at P14. Mechanism analysis showed that Gjb2 35delG disrupts the formation of intercellular gap junction channel and tunnel of Corti, and hair cell mechanotransduction, rather than the development of hair cells. Collectively, our study provides ideal mouse models for understanding the pathogenic mechanism and opens up a new avenue for investigating the treatment for DFNB1A-related hereditary deafness.