Evidence supporting the MICU1 occlusion mechanism and against the potentiation model in the mitochondrial calcium uniporter complex.
Evidence supporting the MICU1 occlusion mechanism and against the potentiation model in the mitochondrial calcium uniporter complex.
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支持MICU1阻断机制的证据和反对线粒体钙单转运体复合体增强模型的证据。
DOI：
10.1073/pnas.2217665120
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发表时间：
2023-04-18
影响因子：
11.1
通讯作者：
Tsai, Ming-Feng
中科院分区：
文献类型：
--
作者：
Tsai, Chen-Wei;Liu, Tsung-Yun;Chao, Fan-Yi;Tu, Yung-Chi;Rodriguez, Madison X.;Van Keuren, Anna M.;Ma, Zhiwei;Bankston, John;Tsai, Ming-Feng
单转运体对正常生理至关重要，其功能障碍与神经退行性疾病、心脏病发作后的组织损伤和癌症等有关。这个Ca2+通道被细胞质Ca2+信号激活，但Ca2+激活的机制还在争论中。一种“闭塞模型”认为，Ca2+结合MICU1亚基释放MICU1闭塞Ca2+通路打开单转运体。然而，一种“增强模型”提出，MICU1不会阻断而是增强单转运子功能。该研究提供了支持MICU1遮挡的证据，并为增强模型的观察结果提供了替代解释。这些结果使该领域更接近于对单转运体和细胞内Ca2+信号传导之间相互作用的统一分子理解。线粒体钙单转运体是一个Ca2+通道，将细胞质Ca2+输入线粒体基质，调节细胞生物能量学、细胞内Ca2+信号传导和细胞凋亡。该单转运体包含成孔MCU亚基、辅助EMRE蛋白和调节MICU1/MICU2亚基。结构和生化研究表明，MICU1通过阻断/解封孔来抑制MCU。然而，有丝分裂体膜片钳实验表明，MICU1不会阻断，而是通过变构机制增强MCU。在这里，我们解决了拟议的MICU1功能的直接冲突。膜片钳研究表明，纯化的MICU1强烈抑制MCU Ca2+电流，这种抑制作用通过突变MCU相互作用的K126残基而被消除。此外，膜去极化分析表明，MICU1在Ca2+无条件下阻止mcu介导的Na+通量进入完整的线粒体。通过对增强模型的观察，我们发现在有丝分裂体中没有检测到MICU1阻断，不是因为MICU1不能阻断，而是因为MICU1从单转运体复合体中解离。此外，MICU1的减少减少了单转运体的传输，不是因为MICU1可以增强MCU，而是因为EMRE的下调。这些结果牢固地确立了MICU1调控单转运子生理关键过程的分子机制。
The uniporter is crucial for normal physiology and its malfunction has been implicated in neurodegenerative diseases, tissue injuries following heart attacks, and cancer, among others. This Ca2+ channel is activated by cytoplasmic Ca2+ signals, but the mechanisms of Ca2+ activation are under debate. An “occlusion model” argues that Ca2+ binding to an MICU1 subunit releases MICU1 occlusion of the Ca2+ pathway to open the uniporter. However, a “potentiation model” proposes that MICU1 does not block but enhances uniporter function. This study provides evidence to support MICU1 occlusion and offers alternative interpretations for the observations underlying the potentiation model. These results bring the field closer to a unifying molecular understanding of the interplay between the uniporter and intracellular Ca2+ signaling. The mitochondrial calcium uniporter is a Ca2+ channel that imports cytoplasmic Ca2+ into the mitochondrial matrix to regulate cell bioenergetics, intracellular Ca2+ signaling, and apoptosis. The uniporter contains the pore-forming MCU subunit, an auxiliary EMRE protein, and the regulatory MICU1/MICU2 subunits. Structural and biochemical studies have suggested that MICU1 gates MCU by blocking/unblocking the pore. However, mitoplast patch-clamp experiments argue that MICU1 does not block, but instead potentiates MCU via allosteric mechanisms. Here, we address this direct clash of the proposed MICU1 function. Supporting the MICU1-occlusion mechanism, patch-clamp demonstrates that purified MICU1 strongly suppresses MCU Ca2+ currents, and this inhibition is abolished by mutating the MCU-interacting K126 residue. Moreover, a membrane-depolarization assay shows that MICU1 prevents MCU-mediated Na+ flux into intact mitochondria under Ca2+-free conditions. Examining the observations underlying the potentiation model, we found that MICU1 occlusion was not detected in mitoplasts not because MICU1 cannot block, but because MICU1 dissociates from the uniporter complex. Furthermore, MICU1 depletion reduces uniporter transport not because MICU1 can potentiate MCU, but because EMRE is down-regulated. These results firmly establish the molecular mechanisms underlying the physiologically crucial process of uniporter regulation by MICU1.
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线粒体Ca（2+）Uniporter的MICU依赖性门控机制。
影响因子：
7.7
作者：
Garg V;Suzuki J;Paranjpe I;Unsulangi T;Boyman L;Milescu LS;Lederer WJ;Kirichok Y
通讯作者：
Kirichok Y
影响因子：
64.5
作者：
Mallilankaraman K;Doonan P;Cárdenas C;Chandramoorthy HC;Müller M;Miller R;Hoffman NE;Gandhirajan RK;Molgó J;Birnbaum MJ;Rothberg BS;Mak DO;Foskett JK;Madesh M
通讯作者：
Madesh M
影响因子：
16
作者：
Tsai, Chen-Wei;Rodriguez, Madison X.;Van Keuren, Anna M.;Phillips, Charles B.;Shushunov, Hannah M.;Lee, Jessica E.;Garcia, Anastacia M.;Ambardekar, Amrut, V;Cleveland, Joseph C.;Reisz, Julie A.;Proenza, Catherine;Chatfield, Kathryn C.;Tsai, Ming-Feng
通讯作者：
Tsai, Ming-Feng
影响因子：
--
作者：
Musa, Sara;Eyaid, Wafaa;Ben-Omran, Tawfeg
通讯作者：
Ben-Omran, Tawfeg
影响因子：
7.7
作者：
Phillips, Charles B.;Tsai, Chen-Wei;Tsai, Ming-Feng
通讯作者：
Tsai, Ming-Feng