The mitochondrial calcium uniporter channel (MCUC) mediates mitochondrial calcium entry, regulating energy metabolism and cell death. Although several MCUC components have been identified, the molecular basis of mitochondrial calcium signaling networks and their remodeling upon changes in uniporter activity have not been assessed. Here, we map the MCUC interactome under resting conditions and upon chronic loss or gain of mitochondrial calcium uptake. We identify 89 high-confidence interactors that link MCUC to several mitochondrial complexes and pathways, half of which are associated with human disease. As a proof-of-concept, we validate the mitochondrial intermembrane space protein EFHD1 as a binding partner of the MCUC subunits MCU, EMRE, and MCUB. We further show a MICU1-dependent inhibitory effect of EFHD1 on calcium uptake. Next, we systematically survey compensatory mechanisms and functional consequences of mitochondrial calcium dyshomeostasis by analyzing the MCU interactome upon EMRE, MCUB, MICU1, or MICU2 knockdown. While silencing EMRE reduces MCU interconnectivity, MCUB loss-of-function leads to a wider interaction network. Our study provides a comprehensive and high-confidence resource to gain insights into players and mechanisms regulating mitochondrial calcium signaling and their relevance in human diseases.

中文翻译：

---

线粒体钙单向转运蛋白通道 （MCUC） 介导的钙信号网络的系统映射。


线粒体钙单向转运蛋白通道 （MCUC） 介导线粒体钙进入，调节能量代谢和细胞死亡。尽管已经确定了几种 MCUC 成分，但尚未评估线粒体钙信号网络的分子基础及其在单向蛋白活性变化时的重塑。在这里，我们绘制了静息条件下以及线粒体钙摄取的慢性损失或增加时的 MCUC 相互作用组。我们确定了 89 个高置信度的相互作用子，它们将 MCUC 与几种线粒体复合物和通路联系起来，其中一半与人类疾病有关。作为概念验证，我们验证了线粒体膜间空间蛋白 EFHD1 作为 MCUC 亚基 MCU 、 EMRE 和 MCUB 的结合伴侣。我们进一步显示了 EFHD1 对钙摄取的 MICU1 依赖性抑制作用。接下来，我们通过分析 EMRE、MCUB、MICU1 或 MICU2 敲低后的 MCU 相互作用组，系统地研究线粒体钙稳态失调的代偿机制和功能后果。虽然沉默 EMRE 会降低 MCU 互连性，但 MCUB 功能丧失会导致更广泛的交互网络。我们的研究提供了一个全面且高可信度的资源，以深入了解调节线粒体钙信号传导的参与者和机制及其在人类疾病中的相关性。