Quantitative proteomics of immunocaptured mitochondria from Astrocytes

Mitochondria vary in morphology and function in different tissues, however little is known about their molecular diversity among cell types. To investigate mitochondrial diversity in vivo, we developed an efficient protocol to isolate cell type-specific mitochondria based on a new MitoTag mouse. We profiled the mitochondrial proteome of three major neural cell types in cerebellum and identified a substantial number of differential mitochondrial markers for these cell types in mice and humans. Based on predictions from these proteomes, we demonstrate that astrocytic mitochondria metabolize long-chain fatty acids more efficiently than neurons. Moreover, we identified Rmdn3 as a major determinant of ER-mitochondria proximity in Purkinje cells. Our novel approach enables exploring mitochondrial diversity on the functional and molecular level in many in vivo contexts.

线粒体的形态与功能随组织类型不同而存在差异，但目前学界对不同细胞类型中线粒体的分子多样性仍缺乏深入了解。为在体研究线粒体多样性，我们基于新型MitoTag小鼠开发了一套高效的细胞类型特异性线粒体分离方案。我们对小脑内三种主要神经细胞类型的线粒体蛋白质组进行了表征，并鉴定出大量可区分小鼠及人类该类细胞类型的线粒体标志物。基于上述蛋白质组的预测分析，我们证实星形胶质细胞线粒体对长链脂肪酸的代谢效率显著高于神经元。此外，我们还鉴定出Rmdn3是浦肯野细胞内质网（Endoplasmic Reticulum, ER）-线粒体邻近连接的关键决定因子。本研究建立的全新方法可在多种在体研究场景中，从功能与分子层面探索线粒体多样性。