Division of Endocrinology, Diabetes and Metabolism, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115.
Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston, MA 02115.
Proc Natl Acad Sci U S A. 2023 Feb 28;120(9):e2216810120. doi: 10.1073/pnas.2216810120. Epub 2023 Feb 22.
Mitochondria provide essential metabolites and adenosine triphosphate (ATP) for the regulation of energy homeostasis. For instance, liver mitochondria are a vital source of gluconeogenic precursors under a fasted state. However, the regulatory mechanisms at the level of mitochondrial membrane transport are not fully understood. Here, we report that a liver-specific mitochondrial inner-membrane carrier SLC25A47 is required for hepatic gluconeogenesis and energy homeostasis. Genome-wide association studies found significant associations between and fasting glucose, HbA1c, and cholesterol levels in humans. In mice, we demonstrated that liver-specific depletion of SLC25A47 impaired hepatic gluconeogenesis selectively from lactate, while significantly enhancing whole-body energy expenditure and the hepatic expression of FGF21. These metabolic changes were not a consequence of general liver dysfunction because acute SLC25A47 depletion in adult mice was sufficient to enhance hepatic FGF21 production, pyruvate tolerance, and insulin tolerance independent of liver damage and mitochondrial dysfunction. Mechanistically, SLC25A47 depletion leads to impaired hepatic pyruvate flux and malate accumulation in the mitochondria, thereby restricting hepatic gluconeogenesis. Together, the present study identified a crucial node in the liver mitochondria that regulates fasting-induced gluconeogenesis and energy homeostasis.
线粒体为能量稳态的调节提供必需的代谢物和三磷酸腺苷 (ATP)。例如,在禁食状态下,肝脏线粒体是糖异生前体的重要来源。然而,线粒体膜转运水平的调节机制尚不完全清楚。在这里,我们报告肝脏特异性线粒体内膜载体 SLC25A47 是肝糖异生和能量稳态所必需的。全基因组关联研究发现与人类的空腹血糖、HbA1c 和胆固醇水平之间存在显著关联。在小鼠中,我们证明了肝脏特异性 SLC25A47 耗竭选择性地损害了来自乳酸的肝糖异生,同时显著增强了全身能量消耗和 FGF21 在肝脏中的表达。这些代谢变化不是一般肝功能障碍的结果,因为在成年小鼠中急性 SLC25A47 耗竭足以增强肝脏 FGF21 的产生、丙酮酸耐量和胰岛素耐量,而与肝损伤和线粒体功能障碍无关。从机制上讲,SLC25A47 耗竭导致肝脏丙酮酸通量受损和线粒体中苹果酸积累,从而限制了肝糖异生。总之,本研究确定了肝脏线粒体中调节空腹诱导的糖异生和能量稳态的关键节点。