Department of Cellular and Molecular Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Chuo-ku, Hamamatsu, Shizuoka 431-3192, Japan.
Quantum Imaging Laboratory, Division of Research and Development in Photonics Technology, Institute of Photonics Medicine, Hamamatsu University School of Medicine, 1-20-1 Handayama, Chuo-ku, Hamamatsu, Shizuoka 431-3192, Japan.
Int J Mol Sci. 2024 Jul 4;25(13):7353. doi: 10.3390/ijms25137353.
Aberrant aggregation of misfolded alpha-synuclein (α-syn), a major pathological hallmark of related neurodegenerative diseases such as Parkinson's disease (PD), can translocate between cells. Ubiquitin-like 3 (UBL3) is a membrane-anchored ubiquitin-fold protein and post-translational modifier. UBL3 promotes protein sorting into small extracellular vesicles (sEVs) and thereby mediates intercellular communication. Our recent studies have shown that α-syn interacts with UBL3 and that this interaction is downregulated after silencing microsomal glutathione S-transferase 3 (MGST3). However, how MGST3 regulates the interaction of α-syn and UBL3 remains unclear. In the present study, we further explored this by overexpressing MGST3. In the split luciferase complementation assay, we found that the interaction between α-syn and UBL3 was upregulated by MGST3. While Western blot and RT-qPCR analyses showed that silencing or overexpression of MGST3 did not significantly alter the expression of α-syn and UBL3, the immunocytochemical staining analysis indicated that MGST3 increased the co-localization of α-syn and UBL3. We suggested roles for the anti-oxidative stress function of MGST3 and found that the effect of MGST3 overexpression on the interaction between α-syn with UBL3 was significantly rescued under excess oxidative stress and promoted intracellular α-syn to extracellular transport. In conclusion, our results demonstrate that MGST3 upregulates the interaction between α-syn with UBL3 and promotes the interaction to translocate intracellular α-syn to the extracellular. Overall, our findings provide new insights and ideas for promoting the modulation of UBL3 as a therapeutic agent for the treatment of synucleinopathy-associated neurodegenerative diseases.
错误折叠的α-突触核蛋白（α-syn）的异常聚集，是帕金森病（PD）等相关神经退行性疾病的主要病理标志之一，它可以在细胞间转移。泛素样 3（UBL3）是一种膜锚定的泛素折叠蛋白和翻译后修饰物。UBL3 促进蛋白质分拣到小细胞外囊泡（sEVs）中，从而介导细胞间通讯。我们最近的研究表明，α-syn 与 UBL3 相互作用，而沉默微粒体谷胱甘肽 S-转移酶 3（MGST3）后，这种相互作用会下调。然而，MGST3 如何调节 α-syn 和 UBL3 的相互作用仍不清楚。在本研究中，我们通过过表达 MGST3 进一步探讨了这一点。在荧光素酶互补测定中，我们发现 MGST3 上调了 α-syn 和 UBL3 之间的相互作用。虽然 Western blot 和 RT-qPCR 分析表明，沉默或过表达 MGST3 不会显著改变 α-syn 和 UBL3 的表达，但免疫细胞化学染色分析表明，MGST3 增加了 α-syn 和 UBL3 的共定位。我们提出了 MGST3 的抗氧化应激功能的作用，并发现在过量氧化应激下，MGST3 过表达对 α-syn 与 UBL3 相互作用的影响显著得到挽救，并促进了细胞内 α-syn 向细胞外的转运。总之，我们的结果表明，MGST3 上调了 α-syn 与 UBL3 的相互作用，并促进了这种相互作用将细胞内的 α-syn 转移到细胞外。总的来说，我们的研究结果为促进 UBL3 的调节作为治疗突触核蛋白病相关神经退行性疾病的治疗剂提供了新的见解和思路。
