Division of Nephrology and Selzman Institute for Kidney Health, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
Center for Translational Research on Inflammatory Diseases (CTRID), Michael E. DeBakey VAMC, Houston, TX, 77030, USA.
Lab Invest. 2022 May;102(5):534-544. doi: 10.1038/s41374-022-00729-3. Epub 2022 Jan 19.
The mitochondrial intracrine Stanniocalcin 1 (STC1) activates mitochondrial anti-oxidant defenses. LRP2 (megalin) shuttles STC1 to the mitochondria through retrograde early endosome-to-Golgi- and Rab32-mediated pathway, and LRP2 KO impairs mitochondrial respiration and glycolysis. We determined STC1-LRP2 interaction domains using HA- and FLAG-tagged fragments of STC1 and LRP2, respectively, co-expressed in HEK293T cells. The trans-membrane domain of LRP2 is required for trafficking to the mitochondria. STC1-FLAG expressed in LRP2 KO cells fails to reach the mitochondria; thus, mitochondrial STC1 is extracellularly-derived via LRP2-mediated trafficking. Tri-leucines L12-14 in LRP2's signal peptide interact with STC1's signal peptide. Mutant LRP2 (L(12-14)A) does not bind STC1, while hSTC1 lacking signal peptide or Leucines L8/9/11 does not bind LRP2. STC1 fails to induce respiration or glycolysis in megalin KO mouse embryonal fibroblasts (MEF) expressing mutant LRP2, while mutant hSTC1 (L8/L9/L11 - > A8/A9/A11) fails to reach the mitochondria or induce respiration and glycolysis in WT MEF. Our data suggest direct regulation of mitochondrial metabolism by extracellular cues and reveal an important role for signal peptides' leucines in protein-protein interactions and mitochondrial biology.
线粒体胞内分泌的 Stanniocalcin 1（STC1）激活线粒体抗氧化防御。LRP2（megalin）通过逆行早期内体-高尔基体和 Rab32 介导的途径将 STC1 转运到线粒体，而 LRP2 KO 会损害线粒体呼吸和糖酵解。我们使用分别在 HEK293T 细胞中表达的 HA 和 FLAG 标记的 STC1 和 LRP2 片段确定了 STC1-LRP2 相互作用域。LRP2 的跨膜结构域是转运到线粒体所必需的。在 LRP2 KO 细胞中表达的 STC1-FLAG 无法到达线粒体；因此，线粒体 STC1 是通过 LRP2 介导的转运从细胞外衍生而来的。LRP2 信号肽中的三亮氨酸 L12-14 与 STC1 的信号肽相互作用。突变 LRP2（L(12-14)A）不与 STC1 结合，而缺乏信号肽或亮氨酸 L8/9/11 的 hSTC1 不与 LRP2 结合。在表达突变 LRP2 的 megalin KO 小鼠胚胎成纤维细胞（MEF）中，STC1 无法诱导呼吸或糖酵解，而突变 hSTC1（L8/L9/L11 - > A8/A9/A11）无法到达线粒体或在 WT MEF 中诱导呼吸和糖酵解。我们的数据表明，细胞外信号可以直接调节线粒体代谢，并揭示了信号肽亮氨酸在蛋白质-蛋白质相互作用和线粒体生物学中的重要作用。
