Department of Biological Sciences, Sungkyunkwan University, Suwon 16419, Republic of Korea.
Cells. 2023 Oct 23;12(20):2504. doi: 10.3390/cells12202504.
The mTOR signaling pathway integrates signaling inputs from nutrients, including glucose and amino acids, which are precisely regulated by transporters depending on nutrient levels. The L-type amino acid transporter 1 (LAT1) affects the activity of mTORC1 through upstream regulators that sense intracellular amino acid levels. While mTORC1 activation by LAT1 has been thoroughly investigated in cultured cells, the effects of LAT1 expression on the activity of mTORC2 has scarcely been studied. Here, we provide evidence that LAT1 recruits and activates mTORC2 on the lysosome for PMA-induced cell migration. LAT1 is translocated to the lysosomes in cells treated with PMA in a dose- and time-dependent manner. Lysosomal LAT1 interacted with mTORC2 through a direct interaction with Rictor, leading to the lysosomal localization of mTORC2. Furthermore, the depletion of LAT1 reduced PMA-induced cell migration in a wound-healing assay. Consistent with these results, the LAT1 N3KR mutant, which is defective in PMA-induced endocytosis and lysosomal localization, did not induce mTORC2 recruitment to the lysosome, with the activation of mTORC2 determined via Akt phosphorylation or the LAT1-mediated promotion of cell migration. Taken together, lysosomal LAT1 recruits and activates the mTORC2 complex and downstream Akt for PMA-mediated cell migration. These results provide insights into the development of therapeutic drugs targeting the LAT1 amino acid transporter to block metastasis, as well as disease progression in various types of cancer.
mTOR 信号通路整合了来自营养物质（包括葡萄糖和氨基酸）的信号输入，这些物质的水平受到转运蛋白的精确调节。L 型氨基酸转运蛋白 1（LAT1）通过感应细胞内氨基酸水平的上游调节剂影响 mTORC1 的活性。虽然在培养细胞中已经彻底研究了 LAT1 对 mTORC1 的激活作用，但 LAT1 表达对 mTORC2 活性的影响几乎没有研究过。在这里，我们提供的证据表明，LAT1 通过募集和激活溶酶体上的 mTORC2 来促进 PMA 诱导的细胞迁移。LAT1 在 PMA 处理的细胞中以剂量和时间依赖的方式被转运到溶酶体中。溶酶体中的 LAT1 通过与 Rictor 的直接相互作用与 mTORC2 相互作用，导致 mTORC2 的溶酶体定位。此外，LAT1 的耗竭减少了 PMA 诱导的划痕愈合试验中的细胞迁移。与这些结果一致的是，LAT1 N3KR 突变体在 PMA 诱导的内吞作用和溶酶体定位中存在缺陷，不会诱导 mTORC2 募集到溶酶体，通过 Akt 磷酸化或 LAT1 介导的促进细胞迁移来确定 mTORC2 的激活。总之，溶酶体 LAT1 募集并激活 mTORC2 复合物及其下游 Akt，以促进 PMA 介导的细胞迁移。这些结果为开发靶向 LAT1 氨基酸转运蛋白的治疗药物以阻断转移以及各种类型癌症的疾病进展提供了新的思路。
