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Chen K, Li C, Dong C, Cen X, Wang Y, Liang Y, Zhu Y, Fang S, Jiang H. A dominant variant in apoptosis-related gene XKR8 is relevant to hereditary auditory neuropathy. J Transl Med 2023; 21:279. [PMID: 37101210 PMCID: PMC10131414 DOI: 10.1186/s12967-023-04139-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 04/16/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND Auditory neuropathy is an unusual type of hearing loss. At least 40% of patients with this disease have underlying genetic causes. However, in many hereditary auditory neuropathy cases, etiology remains undetermined. METHODS We collected data and blood samples from a four-generation Chinese family. After excluding relevant variants in known deafness-related genes, exome sequencing was conducted. Candidate genes were verified by pedigree segregation, transcript/protein expression in the mouse cochlea, and plasmid expression studies in HEK 293T cells. Moreover, a mutant mouse model was generated and underwent hearing evaluations; protein localization in the inner ear was also assessed. RESULTS The clinical features of the family were diagnosed as auditory neuropathy. A novel variant c.710G > A (p.W237X) in apoptosis-related gene XKR8 was identified. Genotyping of 16 family members confirmed the segregation of this variant with the deafness phenotype. Both XKR8 mRNA and XKR8 protein were expressed in the mouse inner ear, predominantly in regions of spiral ganglion neurons; Moreover, this nonsense variant impaired the surface localization of XKR8 in cells. Transgenic mutant mice exhibited late-onset auditory neuropathy, and their altered XKR8 protein localization in the inner ear confirmed the damaging effects of this variant. CONCLUSIONS We identified a variant in the XKR8 gene that is relevant to auditory neuropathy. The essential role of XKR8 in inner ear development and neural homeostasis should be explored.
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Affiliation(s)
- Kaitian Chen
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
| | - Changwu Li
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Department of Otorhinolaryngology, Hainan General Hospital, Haikou, 570311, Hainan, China
| | - Chang Dong
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Department of Otorhinolaryngology, Hainan General Hospital, Haikou, 570311, Hainan, China
| | - Xiaoqing Cen
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
| | - Yueying Wang
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
| | - Yue Liang
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
| | - Yuanping Zhu
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Department of Otorhinolaryngology, Hainan General Hospital, Haikou, 570311, Hainan, China
| | - Shubin Fang
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China
| | - Hongyan Jiang
- Department of Otorhinolaryngology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China.
- Institute of Otorhinolaryngology, Sun Yat-sen University, Guangzhou, 510080, Guangdong, People's Republic of China.
- Department of Otorhinolaryngology, Hainan General Hospital, Haikou, 570311, Hainan, China.
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Abstract
The delivery of therapies to the cochlea is notoriously challenging. It is an organ protected by a number of barriers that need to be overcome in the drug delivery process. Additionally, there are multiple sites of possible damage within the cochlea. Despite the many potential sites of damage, acquired otologic insults preferentially damage a single location. While progress has been made in techniques for inner ear drug delivery, the current techniques remain non-specific and our ability to deliver therapies in a cell-specific manner are limited. Fortunately, there are proteins specific to various cell-types within the cochlea (e.g., hair cells, spiral ganglion cells, stria vascularis) that function as biomarkers of site-specific damage. These protein biomarkers have potential to serve as targets for cell-specific inner ear drug delivery. In this manuscript, we review the concept of biomarkers and targeted- inner ear drug delivery and the well-characterized protein biomarkers within each of the locations of interest within the cochlea. Our review will focus on targeted drug delivery in the setting of acquired otologic insults (e.g., ototoxicity, noise-induce hearing loss). The goal is not to discuss therapies to treat acquired otologic insults, rather, to establish potential concepts of how to deliver therapies in a targeted, cell-specific manner. Based on our review, it is clear that future of inner ear drug delivery is a discipline filled with potential that will require collaborative efforts among clinicians and scientists to optimize treatment of otologic insults. Graphical Abstract ![]()
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