Laboratory of Clinical Pharmaceutics & Therapeutics, Division of Pharmasciences, Faculty of Pharmaceutical Sciences, Hokkaido University.
Department of Pharmacy, Hokkaido University Hospital.
Biol Pharm Bull. 2024;47(4):764-770. doi: 10.1248/bpb.b23-00860.
L-Lactate transport via monocarboxylate transporters (MCTs) in the central nervous system, represented by the astrocyte-neuron lactate shuttle (ANLS), is crucial for the maintenance of brain functions, including memory formation. Previously, we have reported that MCT1 contributes to L-lactate transport in normal human astrocytes. Therefore, in this study, we aimed to identify transporters that contribute to L-lactate transport in human neurons. SH-SY5Y cells, which are used as a model for human neurons, were differentiated using all-trans-retinoic acid. L-Lactate uptake was measured using radiolabeled L-lactate, and the expression of MCT proteins was confirmed Western blotting. L-Lactate transport was pH-dependent and saturated at high concentrations. Kinetic analysis suggested that L-lactate uptake was biphasic. Furthermore, MCT1, 2 selective inhibitors inhibited L-lactate transport. In addition, the expression of MCT1 and 2 proteins, but not MCT4, was confirmed. In this study, we demonstrated that MCT1 and 2 are major contributors to L-lactate transport in differentiated human neuroblastoma SH-SY5Y cells from the viewpoint of kinetic analysis. These results lead to a better understanding of ANLS in humans, and further exploration of the factors that can promote MCT1 and 2 functions is required.
L-乳酸通过单羧酸转运蛋白（MCTs）在中枢神经系统中的转运，由星形胶质细胞-神经元乳酸穿梭（ANLS）来代表，对于维持脑功能至关重要，包括记忆形成。此前，我们报道了 MCT1 有助于正常人类星形胶质细胞中的 L-乳酸转运。因此，在这项研究中，我们旨在确定在人类神经元中有助于 L-乳酸转运的转运蛋白。使用全反式视黄酸将 SH-SY5Y 细胞分化为人类神经元模型。使用放射性标记的 L-乳酸测量 L-乳酸摄取，并通过 Western blot 确认 MCT 蛋白的表达。L-乳酸转运依赖 pH 值，并在高浓度下达到饱和。动力学分析表明，L-乳酸摄取呈双相性。此外，MCT1、2 选择性抑制剂抑制 L-乳酸转运。此外，还证实了 MCT1 和 2 蛋白的表达，但没有 MCT4 蛋白的表达。在这项研究中，我们从动力学分析的角度表明，MCT1 和 2 是分化的人类神经母细胞瘤 SH-SY5Y 细胞中 L-乳酸转运的主要贡献者。这些结果有助于更好地理解人类的 ANLS，需要进一步探索可以促进 MCT1 和 2 功能的因素。
