1
|
Liu S, Zhou M, Ruan Z, Wang Y, Chang C, Sasaki M, Rajaram V, Lemoff A, Nambiar K, Wang JE, Hatanpaa KJ, Luo W, Dawson TM, Dawson VL, Wang Y. AIF3 splicing switch triggers neurodegeneration. Mol Neurodegener 2021; 16:25. [PMID: 33853653 PMCID: PMC8048367 DOI: 10.1186/s13024-021-00442-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Accepted: 03/12/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Apoptosis-inducing factor (AIF), as a mitochondrial flavoprotein, plays a fundamental role in mitochondrial bioenergetics that is critical for cell survival and also mediates caspase-independent cell death once it is released from mitochondria and translocated to the nucleus under ischemic stroke or neurodegenerative diseases. Although alternative splicing regulation of AIF has been implicated, it remains unknown which AIF splicing isoform will be induced under pathological conditions and how it impacts mitochondrial functions and neurodegeneration in adult brain. METHODS AIF splicing induction in brain was determined by multiple approaches including 5' RACE, Sanger sequencing, splicing-specific PCR assay and bottom-up proteomic analysis. The role of AIF splicing in mitochondria and neurodegeneration was determined by its biochemical properties, cell death analysis, morphological and functional alterations and animal behavior. Three animal models, including loss-of-function harlequin model, gain-of-function AIF3 knockin model and conditional inducible AIF splicing model established using either Cre-loxp recombination or CRISPR/Cas9 techniques, were applied to explore underlying mechanisms of AIF splicing-induced neurodegeneration. RESULTS We identified a nature splicing AIF isoform lacking exons 2 and 3 named as AIF3. AIF3 was undetectable under physiological conditions but its expression was increased in mouse and human postmortem brain after stroke. AIF3 splicing in mouse brain caused enlarged ventricles and severe neurodegeneration in the forebrain regions. These AIF3 splicing mice died 2-4 months after birth. AIF3 splicing-triggered neurodegeneration involves both mitochondrial dysfunction and AIF3 nuclear translocation. We showed that AIF3 inhibited NADH oxidase activity, ATP production, oxygen consumption, and mitochondrial biogenesis. In addition, expression of AIF3 significantly increased chromatin condensation and nuclear shrinkage leading to neuronal cell death. However, loss-of-AIF alone in harlequin or gain-of-AIF3 alone in AIF3 knockin mice did not cause robust neurodegeneration as that observed in AIF3 splicing mice. CONCLUSIONS We identified AIF3 as a disease-inducible isoform and established AIF3 splicing mouse model. The molecular mechanism underlying AIF3 splicing-induced neurodegeneration involves mitochondrial dysfunction and AIF3 nuclear translocation resulting from the synergistic effect of loss-of-AIF and gain-of-AIF3. Our study provides a valuable tool to understand the role of AIF3 splicing in brain and a potential therapeutic target to prevent/delay the progress of neurodegenerative diseases.
Collapse
Affiliation(s)
- Shuiqiao Liu
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Mi Zhou
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Zhi Ruan
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Yanan Wang
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Calvin Chang
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Masayuki Sasaki
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Veena Rajaram
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Andrew Lemoff
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Kalyani Nambiar
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Jennifer E. Wang
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Kimmo J. Hatanpaa
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Weibo Luo
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Ted M. Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Valina L. Dawson
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| | - Yingfei Wang
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Neurology, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
- Departments of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205 USA
| |
Collapse
|