Lehotzky Attila, Oláh Judit, Fekete János Tibor, Szénási Tibor, Szabó Edit, Győrffy Balázs, Várady György, Ovádi Judit
Institute of Enzymology, Research Center for Natural Sciences, Budapest, Hungary.
Front Mol Biosci. 2021 May 18;8:666026. doi: 10.3389/fmolb.2021.666026. eCollection 2021.
The pathological association of alpha-synuclein (SYN) and Tubulin Polymerization Promoting Protein (TPPP/p25) is a key factor in the etiology of synucleinopathies. In normal brains, the intrinsically disordered SYN and TPPP/p25 are not found together but exist separately in neurons and oligodendrocytes, respectively; in pathological states, however, they are found in both cell types due to their cell-to-cell transmission. The autophagy degradation of the accumulated/assembled SYN has been considered as a potential therapeutic target. We have shown that the hetero-association of SYN with TPPP/p25 after their uptake from the medium by human cells (which mimics cell-to-cell transmission) inhibits both their autophagy- and the ubiquitin-proteasome system-derived elimination. These results were obtained by ELISA, Western blot, FACS and immunofluorescence confocal microscopy using human recombinant proteins and living human cells; ANOVA statistical analysis confirmed that TPPP/p25 counteracts SYN degradation by hindering the autophagy maturation at the stage of LC3B-SQSTM1/p62-derived autophagosome formation and its fusion with lysosome. Recently, fragments of TPPP/p25 that bind to the interface between the two hallmark proteins have been shown to inhibit their pathological assembly. In this work, we show that the proteolytic degradation of SYN on its own is more effective than when it is complexed with TPPP/p25. The combined strategy of TPPP/p25 fragments and proteolysis may ensure prevention and/or elimination of pathological SYN assemblies.
α-突触核蛋白（SYN）与微管蛋白聚合促进蛋白（TPPP/p25）的病理关联是突触核蛋白病病因学中的关键因素。在正常大脑中，内在无序的SYN和TPPP/p25不会同时出现，而是分别存在于神经元和少突胶质细胞中；然而，在病理状态下，由于它们在细胞间的传递，在这两种细胞类型中都能发现它们。积累/组装的SYN的自噬降解被认为是一个潜在的治疗靶点。我们已经表明，人类细胞从培养基中摄取SYN和TPPP/p25后（模拟细胞间传递），它们的异源结合会抑制它们通过自噬和泛素-蛋白酶体系统的清除。这些结果是通过使用人类重组蛋白和活的人类细胞进行ELISA、蛋白质印迹、流式细胞术和免疫荧光共聚焦显微镜获得的；方差分析统计分析证实，TPPP/p25通过在LC3B-SQSTM1/p62衍生的自噬体形成阶段阻碍自噬成熟及其与溶酶体的融合来抵消SYN的降解。最近，已证明与这两种标志性蛋白之间的界面结合的TPPP/p25片段可抑制它们的病理组装。在这项工作中，我们表明SYN自身的蛋白水解降解比与TPPP/p25复合时更有效。TPPP/p25片段和蛋白水解的联合策略可能确保预防和/或消除病理性SYN组装。
