Yuan Yueming, Fang An, Wang Haoran, Wang Caiqian, Sui Baokun, Zhao Jianqing, Fu Zhen F, Zhou Ming, Zhao Ling
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, China.
Key Laboratory of Preventive Veterinary Medicine of Hubei Province, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.
mBio. 2024 Mar 13;15(3):e0288023. doi: 10.1128/mbio.02880-23. Epub 2024 Feb 13.
Infection with neurotropic viruses may result in changes in host behavior, which are closely associated with degenerative changes in neurons. The lyssavirus genus comprises highly neurotropic viruses, including the rabies virus (RABV), which has been shown to induce degenerative changes in neurons, marked by the self-destruction of axons. The underlying mechanism by which the RABV degrades neuronal cytoskeletal proteins remains incomplete. In this study, we show that infection with RABV or overexpression of its M protein can disrupt mitochondrial metabolism by binding to Slc25a4. This leads to a reduction in NAD production and a subsequent influx of Ca from the endoplasmic reticulum and mitochondria into the cytoplasm of neuronal cell lines, activating Ca-dependent proteinase calpains that degrade α-tubulin. We further screened the M proteins of different lyssaviruses and discovered that the M protein of the dog-derived RABV strain (DRV) does not degrade α-tubulin. Sequence analysis of the DRV M protein and that of the lab-attenuated RABV strain CVS revealed that the 57th amino acid is vital for M-induced microtubule degradation. We generated a recombinant RABV with a mutation at the 57th amino acid position in its M protein and showed that this mutation reduces α-tubulin degradation and axonal degeneration . This study elucidates the mechanism by which lyssavirus induces neuron degeneration.IMPORTANCEPrevious studies have suggested that RABV (rabies virus, the representative of lyssavirus) infection induces structural abnormalities in neurons. But there are few articles on the mechanism of lyssavirus' effect on neurons, and the mechanism of how RABV infection induces neurological dysfunction remains incomplete. The M protein of lyssavirus can downregulate cellular ATP levels by interacting with Slc25a4, and this decrease in ATP leads to a decrease in the level of NAD in the cytosol, which results in the release of Ca from the intracellular calcium pool, the endoplasmic reticulum, and mitochondria. The presence of large amounts of Ca in the cytoplasm activates Ca-dependent proteases and degrades microtubule proteins. The amino acid 57 of M protein is the key site determining its disruption of mitochondrial metabolism and subsequent neuron degeneration.
感染嗜神经病毒可能导致宿主行为发生变化，这与神经元的退行性变化密切相关。狂犬病病毒属包含高度嗜神经病毒，包括狂犬病病毒（RABV），已证明其可诱导神经元发生退行性变化，其特征为轴突的自我破坏。RABV降解神经元细胞骨架蛋白的潜在机制仍不完整。在本研究中，我们表明感染RABV或其M蛋白的过表达可通过与Slc25a4结合来破坏线粒体代谢。这导致NAD生成减少，随后内质网和线粒体中的Ca流入神经元细胞系的细胞质，激活降解α-微管蛋白的钙依赖性蛋白酶钙蛋白酶。我们进一步筛选了不同狂犬病病毒的M蛋白，发现犬源RABV毒株（DRV）的M蛋白不会降解α-微管蛋白。对DRV M蛋白和实验室减毒RABV毒株CVS的序列分析表明，第57位氨基酸对于M诱导的微管降解至关重要。我们构建了一种在其M蛋白第57位氨基酸位置发生突变的重组RABV，并表明该突变减少了α-微管蛋白降解和轴突变性。本研究阐明了狂犬病病毒诱导神经元变性的机制。重要性先前的研究表明，RABV（狂犬病病毒，狂犬病病毒属的代表）感染会诱导神经元结构异常。但关于狂犬病病毒属对神经元作用机制的文章很少，且RABV感染如何诱导神经功能障碍的机制仍不完整。狂犬病病毒属的M蛋白可通过与Slc25a4相互作用下调细胞ATP水平，而ATP的这种降低导致细胞质中NAD水平下降，从而导致细胞内钙库、内质网和线粒体释放Ca。细胞质中大量Ca的存在激活钙依赖性蛋白酶并降解微管蛋白。M蛋白的第57位氨基酸是决定其破坏线粒体代谢及随后神经元变性的关键位点。
