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Shi T, Chen Z, Li J, Wang H, Wang Q. AIF translocation into nucleus caused by Aifm1 R450Q mutation: generation and characterization of a mouse model for AUNX1. Hum Mol Genet 2024; 33:905-918. [PMID: 38449065 PMCID: PMC11070138 DOI: 10.1093/hmg/ddae010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/30/2023] [Accepted: 01/05/2024] [Indexed: 03/08/2024] Open
Abstract
Mutations in AIFM1, encoding for apoptosis-inducing factor (AIF), cause AUNX1, an X-linked neurologic disorder with late-onset auditory neuropathy (AN) and peripheral neuropathy. Despite significant research on AIF, there are limited animal models with the disrupted AIFM1 representing the corresponding phenotype of human AUNX1, characterized by late-onset hearing loss and impaired auditory pathways. Here, we generated an Aifm1 p.R450Q knock-in mouse model (KI) based on the human AIFM1 p.R451Q mutation. Hemizygote KI male mice exhibited progressive hearing loss from P30 onward, with greater severity at P60 and stabilization until P210. Additionally, muscle atrophy was observed at P210. These phenotypic changes were accompanied by a gradual reduction in the number of spiral ganglion neuron cells (SGNs) at P30 and ribbons at P60, which coincided with the translocation of AIF into the nucleus starting from P21 and P30, respectively. The SGNs of KI mice at P210 displayed loss of cytomembrane integrity, abnormal nuclear morphology, and dendritic and axonal demyelination. Furthermore, the inner hair cells and myelin sheath displayed abnormal mitochondrial morphology, while fibroblasts from KI mice showed impaired mitochondrial function. In conclusion, we successfully generated a mouse model recapitulating AUNX1. Our findings indicate that disruption of Aifm1 induced the nuclear translocation of AIF, resulting in the impairment in the auditory pathway.
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Affiliation(s)
- Tao Shi
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of PLA General Hospital, Medical School of Chinese PLA, 6 Fucheng Road, Beijing 100048, P. R. China
- National Clinical Research Center for Otolaryngologic Diseases, Chinese PLA General Hospital, 6 Fucheng Road, Beijing 100048, P. R. China
| | - Ziyi Chen
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of PLA General Hospital, Medical School of Chinese PLA, 6 Fucheng Road, Beijing 100048, P. R. China
- National Clinical Research Center for Otolaryngologic Diseases, Chinese PLA General Hospital, 6 Fucheng Road, Beijing 100048, P. R. China
| | - Jin Li
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of PLA General Hospital, Medical School of Chinese PLA, 6 Fucheng Road, Beijing 100048, P. R. China
- National Clinical Research Center for Otolaryngologic Diseases, Chinese PLA General Hospital, 6 Fucheng Road, Beijing 100048, P. R. China
| | - Hongyang Wang
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of PLA General Hospital, Medical School of Chinese PLA, 6 Fucheng Road, Beijing 100048, P. R. China
- National Clinical Research Center for Otolaryngologic Diseases, Chinese PLA General Hospital, 6 Fucheng Road, Beijing 100048, P. R. China
| | - Qiuju Wang
- Senior Department of Otolaryngology-Head and Neck Surgery, the Sixth Medical Center of PLA General Hospital, Medical School of Chinese PLA, 6 Fucheng Road, Beijing 100048, P. R. China
- National Clinical Research Center for Otolaryngologic Diseases, Chinese PLA General Hospital, 6 Fucheng Road, Beijing 100048, P. R. China
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Fagnani E, Cocomazzi P, Pellegrino S, Tedeschi G, Scalvini FG, Cossu F, Da Vela S, Aliverti A, Mastrangelo E, Milani M. CHCHD4 binding affects the active site of apoptosis inducing factor (AIF): Structural determinants for allosteric regulation. Structure 2024; 32:594-602.e4. [PMID: 38460521 DOI: 10.1016/j.str.2024.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 01/08/2024] [Accepted: 02/13/2024] [Indexed: 03/11/2024]
Abstract
Apoptosis-inducing factor (AIF), which is confined to mitochondria of normal healthy cells, is the first identified caspase-independent cell death effector. Moreover, AIF is required for the optimal functioning of the respiratory chain machinery. Recent findings have revealed that AIF fulfills its pro-survival function by interacting with CHCHD4, a soluble mitochondrial protein which promotes the entrance and the oxidative folding of different proteins in the inner membrane space. Here, we report the crystal structure of the ternary complex involving the N-terminal 27-mer peptide of CHCHD4, NAD+, and AIF harboring its FAD (flavin adenine dinucleotide) prosthetic group in oxidized form. Combining this information with biophysical and biochemical data on the CHCHD4/AIF complex, we provide a detailed structural description of the interaction between the two proteins, validated by both chemical cross-linking mass spectrometry analysis and site-directed mutagenesis.
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Affiliation(s)
- Elisa Fagnani
- Biophysics Institute, CNR-IBF, Via Corti 12, 20133 Milan, Italy; Department of Bioscience, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Paolo Cocomazzi
- Biophysics Institute, CNR-IBF, Via Corti 12, 20133 Milan, Italy; Department of Bioscience, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Sara Pellegrino
- Department of Pharmaceutical Sciences, Università degli Studi di Milano, Via Golgi 19, 20133 Milan, Italy
| | - Gabriella Tedeschi
- Department of Veterinary Medicine and Animal Science (DIVAS), Università degli Studi di Milano, Via dell'Università 6, 26900 Lodi, Italy; Cimaina, Università degli Studi di Milano, Milan, Italy
| | - Francesca Grassi Scalvini
- Department of Veterinary Medicine and Animal Science (DIVAS), Università degli Studi di Milano, Via dell'Università 6, 26900 Lodi, Italy
| | - Federica Cossu
- Biophysics Institute, CNR-IBF, Via Corti 12, 20133 Milan, Italy; Department of Bioscience, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy
| | - Stefano Da Vela
- Hochschule Bremerhaven, Karlstadt 8, 27568 Bremerhaven, Germany
| | - Alessandro Aliverti
- Department of Bioscience, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
| | - Eloise Mastrangelo
- Biophysics Institute, CNR-IBF, Via Corti 12, 20133 Milan, Italy; Department of Bioscience, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
| | - Mario Milani
- Biophysics Institute, CNR-IBF, Via Corti 12, 20133 Milan, Italy; Department of Bioscience, Università degli Studi di Milano, Via Celoria 26, 20133 Milan, Italy.
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Qiu Y, Wang H, Pan H, Ding X, Guan J, Zhuang Q, Wu K, Lei Z, Cai H, Dong Y, Zhou H, Lin A, Wang Q, Yan Q. NADH improves AIF dimerization and inhibits apoptosis in iPSCs-derived neurons from patients with auditory neuropathy spectrum disorder. Hear Res 2024; 441:108919. [PMID: 38043402 DOI: 10.1016/j.heares.2023.108919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/08/2023] [Accepted: 11/20/2023] [Indexed: 12/05/2023]
Abstract
Auditory neuropathy spectrum disorder (ANSD) is a hearing impairment involving disruptions to inner hair cells (IHCs), ribbon synapses, spiral ganglion neurons (SGNs), and/or the auditory nerve itself. The outcomes of cochlear implants (CI) for ANSD are variable and dependent on the location of lesion sites. Discovering a potential therapeutic agent for ANSD remains an urgent requirement. Here, 293T stable transfection cell lines and patient induced pluripotent stem cells (iPSCs)-derived auditory neurons carrying the apoptosis inducing factor (AIF) p.R422Q variant were used to pursue a therapeutic regent for ANSD. Nicotinamide adenine dinucleotide (NADH) is a main electron donor in the electron transport chain (ETC). In 293T stable transfection cells with the p.R422Q variant, NADH treatment improved AIF dimerization, rescued mitochondrial dysfunctions, and decreased cell apoptosis. The effects of NADH were further confirmed in patient iPSCs-derived neurons. The relative level of AIF dimers was increased to 150.7 % (P = 0.026) from 59.2 % in patient-neurons upon NADH treatment. Such increased AIF dimerization promoted the mitochondrial import of coiled-coil-helix-coiled-coil-helix domain-containing protein 4 (CHCHD4), which further restored mitochondrial functions. Similarly, the content of mitochondrial calcium (mCa2+) was downregulated from 136.7 % to 102.3 % (P = 0.0024) in patient-neurons upon NADH treatment. Such decreased mCa2+ levels inhibited calpain activity, ultimately reducing the percentage of apoptotic cells from 30.5 % to 21.1 % (P = 0.021). We also compared the therapeutic effects of gene correction and NADH treatment on hereditary ANSD. NADH treatment had comparable restorative effects on functions of ANSD patient-specific cells to that of gene correction. Our findings offer evidence of the molecular mechanisms of ANSD and introduce NADH as a potential therapeutic agent for ANSD therapy.
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Affiliation(s)
- Yue Qiu
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Institute of Brain Science, Wannan Medical College, Wuhu, Anhui 241000, China
| | - Hongyang Wang
- Department of Audiology and Vestibular Medicine, Senior Department of Otolaryngology, Head and Neck Surgery, Chinese PLA Institute of Otolaryngology, the Sixth Medicine Center of Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China
| | - Huaye Pan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xue Ding
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Jing Guan
- Department of Audiology and Vestibular Medicine, Senior Department of Otolaryngology, Head and Neck Surgery, Chinese PLA Institute of Otolaryngology, the Sixth Medicine Center of Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China
| | - Qianqian Zhuang
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Kaiwen Wu
- Department of Audiology and Vestibular Medicine, Senior Department of Otolaryngology, Head and Neck Surgery, Chinese PLA Institute of Otolaryngology, the Sixth Medicine Center of Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China
| | - Zhaoying Lei
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Huajian Cai
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yufei Dong
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Hui Zhou
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Aifu Lin
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Qiuju Wang
- Department of Audiology and Vestibular Medicine, Senior Department of Otolaryngology, Head and Neck Surgery, Chinese PLA Institute of Otolaryngology, the Sixth Medicine Center of Chinese PLA General Hospital, 28 Fuxing Road, Beijing 100853, China
| | - Qingfeng Yan
- College of Life Science, Zhejiang University, Hangzhou, Zhejiang 310058, China; Department of Pediatrics, The First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, China; Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Hangzhou, Zhejiang 310058, China.
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