Kumar Ashutosh, Zhao Yonghui, Xie Litao, Chadda Rahul, Abraham Nihil, Hong Juan, Feng Ethan, Tranter John D, Rawnsley David, Liu Haiyan, Henry Kyla M, Meyer Gretchen, Hu Meiqin, Xu Haoxing, Hinton Antentor, Grueter Chad E, Abel E Dale, Norris Andrew W, Diwan Abhinav, Sah Rajan
bioRxiv. 2024 Sep 23:2024.09.22.614256. doi: 10.1101/2024.09.22.614256.
The lysosome integrates anabolic signalling and nutrient-sensing to regulate intracellular growth pathways. The leucine-rich repeat containing 8 (LRRC8) channel complex forms a lysosomal anion channel and regulates PI3K-AKT-mTOR signalling, skeletal muscle differentiation, growth, and systemic glucose metabolism. Here, we define the endogenous LRRC8 subunits localized to a subset of lysosomes in differentiated myotubes. We show LRRC8A regulates leucine-stimulated mTOR, lysosome size, number, pH, and expression of lysosomal proteins LAMP2, P62, LC3B, suggesting impaired autophagic flux. Mutating a LRRC8A lysosomal targeting dileucine motif sequence (LRRC8A-L706A;L707A) in myotubes recapitulates the abnormal AKT signalling and altered lysosomal morphology and pH observed in LRRC8A KO cells. , LRRC8A-L706A;L707A KI mice exhibit increased adiposity, impaired glucose tolerance and insulin resistance characterized by reduced skeletal muscle glucose-uptake, and impaired incorporation of glucose into glycogen. These data reveal a lysosomal LRRC8 mediated metabolic signalling function that regulates lysosomal activity, systemic glucose homeostasis and insulin-sensitivity.
溶酶体整合合成代谢信号和营养感知以调节细胞内生长途径。富含亮氨酸重复序列8（LRRC8）通道复合物形成溶酶体阴离子通道，并调节PI3K-AKT-mTOR信号传导、骨骼肌分化、生长和全身葡萄糖代谢。在这里，我们确定了定位于分化肌管中一部分溶酶体的内源性LRRC8亚基。我们发现LRRC8A调节亮氨酸刺激的mTOR、溶酶体大小、数量、pH值以及溶酶体蛋白LAMP2、P62、LC3B的表达，提示自噬通量受损。在肌管中突变LRRC8A溶酶体靶向双亮氨酸基序序列（LRRC8A-L706A;L707A）可重现LRRC8A基因敲除细胞中观察到的异常AKT信号传导以及溶酶体形态和pH值的改变。此外，LRRC8A-L706A;L707A基因敲入小鼠表现出肥胖增加、葡萄糖耐量受损和胰岛素抵抗，其特征为骨骼肌葡萄糖摄取减少以及葡萄糖合成糖原受损。这些数据揭示了溶酶体LRRC8介导的代谢信号功能，该功能调节溶酶体活性、全身葡萄糖稳态和胰岛素敏感性。
