Department of Psychiatry and Psychotherapy, University of Regensburg, 93953 Regensburg, Germany.
Department of Anesthesiology, University of Regensburg, 93953 Regensburg, Germany.
Psychoneuroendocrinology. 2019 Aug;106:65-76. doi: 10.1016/j.psyneuen.2019.03.029. Epub 2019 Mar 29.
The translocator protein 18 kDa (TSPO), initially characterized as peripheral benzodiazepine receptor, is a conserved outer mitochondrial membrane protein, implicated in cholesterol transport thereby affecting steroid hormone biosynthesis, as well as in general mitochondrial function related to bioenergetics, oxidative stress, and Ca homeostasis. TSPO is highly expressed in steroidogenic tissues such as adrenal glands, but shows low expression in the central nervous system. During various disease states such as inflammation, neurodegeneration or cancer, the expression of mitochondrial TSPO in affected tissues is upregulated. The expression of TSPO can be traced for diagnostic purpose by high affinity radio-ligands. Moreover, the function of TSPO is modulated by synthetic as well as endogenous ligands with agonistic or antagonistic properties. Thus, TSPO ligands serve functions as both important biomarkers and putative therapeutic agents. In the present study, we aimed to characterize the effects of TSPO ligands on mouse BV-2 microglia cells, which express significant levels of TSPO, and analyzed the effect of XBD173, PK11195, and Ro5-4864, as well as the inflammatory reagent Lipopolysaccharides (LPS) on neurosteroid synthesis and on basic mitochondrial functions such as oxidative phosphorylation, mitochondrial membrane potential and Ca homeostasis. Specific TSPO-dependent effects were separated from off-target effects by comparing lentiviral TSPO knockdown with shRNA scramble-controls and wild-type BV-2 cells. Our data demonstrate ligand-specific effects on different cellular functions in a TSPO-dependent or independent manner, providing evidence for both specific TSPO-mediated, as well as off-target effects.
转位蛋白 18kDa（TSPO）最初被描述为外周苯二氮䓬受体，是一种保守的线粒体外膜蛋白，参与胆固醇转运，从而影响类固醇激素的生物合成，以及与生物能量学、氧化应激和 Ca 稳态相关的一般线粒体功能。TSPO 在类固醇生成组织中高度表达，如肾上腺，但在中枢神经系统中表达较低。在炎症、神经退行性变或癌症等各种疾病状态下，受影响组织中线粒体 TSPO 的表达上调。TSPO 的表达可以通过高亲和力放射性配体进行追踪，用于诊断目的。此外，TSPO 的功能受具有激动剂或拮抗剂特性的合成和内源性配体调节。因此，TSPO 配体既是重要的生物标志物，也是潜在的治疗剂。在本研究中，我们旨在研究 TSPO 配体对表达高水平 TSPO 的小鼠 BV-2 小胶质细胞的影响，并分析 XBD173、PK11195 和 Ro5-4864 以及炎症试剂脂多糖（LPS）对神经甾体合成以及基本线粒体功能（如氧化磷酸化、线粒体膜电位和 Ca 稳态）的影响。通过比较慢病毒 TSPO 敲低与 shRNA 对照和野生型 BV-2 细胞，将特定的 TSPO 依赖性作用与脱靶作用分离。我们的数据表明，配体以 TSPO 依赖性或非依赖性方式对不同的细胞功能具有特异性作用，为 TSPO 介导的特异性作用以及脱靶作用提供了证据。
