Amino acid transporters play a vital role in cellular homeostasis by maintaining protein synthesis. L-type amino acid transporter 1 (LAT1/SLC7A5/CD98lc) is a major transporter of large neutral amino acids in cancer cells because of its predominant expression. Although amino acid restriction with various amino acid analog treatments is known to induce mitotic defects, the involvement of amino acid transporters in cell division remains unclear. In this study, we identified that LAT1 is responsible for mitotic progression in a transport activity-independent manner. LAT1 knockdown activates the spindle assembly checkpoint, leading to a delay in metaphase. LAT1 maintains proper spindle orientation with confinement of the lateral cortex localization of the NuMA protein, which mediates the pulling force against the mitotic spindle toward the lateral cortex. Unexpectedly, JPH203, an inhibitor of LAT1 amino acid transport activity, does not affect mitotic progression. Moreover, the transport activity-deficient LAT1 mutant maintains the proper spindle orientation and mitotic progression. LAT1 forms a heterodimer with CD98 (SLC3A2/CD98hc) both in interphase and mitosis. Although CD98 knockdown decreases the plasma membrane localization of LAT1, it does not affect mitotic progression. LAT1 is localized to the Golgi and ER not only at the plasma membrane in interphase, and promotes Golgi unlinking during the mitotic entry, leading to centrosome maturation. These results suggest that LAT1 supports mitotic progression in an amino acid transport activity-independent manner and that Golgi-localized LAT1 is important for mitotic progression through the acceleration of Golgi unlinking and centrosome maturation. These findings reveal a novel LAT1 function in mitosis.

中文翻译：

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LAT1 通过高尔基体以不依赖氨基酸转运活性的方式解开支持有丝分裂进程


氨基酸转运蛋白通过维持蛋白质合成在细胞稳态中起着至关重要的作用。L 型氨基酸转运蛋白 1 （LAT1/SLC7A5/CD98lc） 是癌细胞中大中性氨基酸的主要转运蛋白，因为它主要表达。尽管已知使用各种氨基酸类似物处理限制氨基酸会诱导有丝分裂缺陷，但氨基酸转运蛋白参与细胞分裂的情况仍不清楚。在这项研究中，我们确定 LAT1 以不依赖运输活动的方式负责有丝分裂进程。LAT1 敲除激活纺锤体组装检查点，导致中期延迟。LAT1 通过限制 NuMA 蛋白的外侧皮层定位来保持正确的纺锤体方向，这介导了对有丝分裂纺锤体向外侧皮层的拉力。出乎意料的是，JPH203 是 LAT1 氨基酸转运活性的抑制剂，不会影响有丝分裂进程。此外，转运活性缺陷的 LAT1 突变体保持正确的纺锤体方向和有丝分裂进程。LAT1 在间期和有丝分裂中与 CD98 （SLC3A2/CD98hc） 形成异二聚体。尽管 CD98 敲低降低了 LAT1 的质膜定位，但它不会影响有丝分裂进程。LAT1 不仅位于间期的质膜上，还定位于高尔基体和 ER，并在有丝分裂进入过程中促进高尔基体脱钩，导致中心体成熟。这些结果表明，LAT1 以不依赖氨基酸转运活动的方式支持有丝分裂进程，并且高尔基体定位的 LAT1 通过加速高尔基体脱钩和中心体成熟对有丝分裂进程很重要。这些发现揭示了有丝分裂中一种新的 LAT1 功能。