Dementia Research Centre, Faculty of Health and Medical Sciences, Macquarie University, Sydney, NSW, Australia.
Mark Wainwright Analytical Centre, University of New South Wales, Sydney, Australia.
PLoS One. 2022 May 6;17(5):e0254296. doi: 10.1371/journal.pone.0254296. eCollection 2022.
The translocator protein (TSPO) has been implicated in mitochondrial transmembrane cholesterol transport, brain inflammation, and other mitochondrial functions. It is upregulated in glial cells during neuroinflammation in Alzheimer's disease. High affinity TSPO imaging radioligands are utilized to visualize neuroinflammation. However, this is hampered by the common A147T polymorphism which compromises ligand binding. Furthermore, this polymorphism has been linked to increased risk of neuropsychiatric disorders, and possibly reduces TSPO protein stability. Here, we used immunoprecipitation coupled to mass-spectrometry (IP-MS) to establish a mitochondrial protein binding profile of wild-type (WT) TSPO and the A147T polymorphism variant. Using mitochondria from human glial cells expressing either WT or A147T TSPO, we identified 30 WT TSPO binding partners, yet only 23 for A147T TSPO. Confirming that A147T polymorphism of the TSPO might confer loss of function, we found that one of the identified interactors of WT TSPO, 14-3-3 theta (YWHAQ), a protein involved in regulating mitochondrial membrane proteins, interacts much less with A147T TSPO. Our data presents a network of mitochondrial interactions of TSPO and its A147T polymorphism variant in human glial cells and indicate functional relevance of A147T in mitochondrial protein networks.
转位蛋白（TSPO）已被牵连到线粒体跨膜胆固醇转运、脑炎症和其他线粒体功能中。在阿尔茨海默病的神经炎症中，TSPO 在神经胶质细胞中上调。高亲和力 TSPO 成像放射性配体用于可视化神经炎症。然而，这受到常见的 A147T 多态性的阻碍，该多态性会损害配体结合。此外，这种多态性与神经精神障碍的风险增加有关，并且可能降低 TSPO 蛋白稳定性。在这里，我们使用免疫沉淀结合质谱（IP-MS）来建立野生型（WT）TSPO 和 A147T 多态性变体的线粒体蛋白结合图谱。使用表达 WT 或 A147T TSPO 的人神经胶质细胞的线粒体，我们鉴定出 30 个 WT TSPO 结合伴侣，但仅鉴定出 A147T TSPO 的 23 个。证实 TSPO 的 A147T 多态性可能导致功能丧失，我们发现 WT TSPO 的一个鉴定出的相互作用物 14-3-3 theta（YWHAQ），一种参与调节线粒体膜蛋白的蛋白质，与 A147T TSPO 的相互作用要少得多。我们的数据展示了人神经胶质细胞中 TSPO 及其 A147T 多态性变体的线粒体相互作用网络，并表明 A147T 在线粒体蛋白网络中的功能相关性。
