Department of Anesthesiology, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan.
Institute of Medical Science, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo 160-8402, Japan.
Cells. 2021 Feb 20;10(2):453. doi: 10.3390/cells10020453.
Choline and choline metabolites are essential for all cellular functions. They have also been reported to be crucial for neural development. In this work, we studied the functional characteristics of the choline uptake system in human neural stem cells (hNSCs). Additionally, we investigated the effect of extracellular choline uptake inhibition on the cellular activities in hNSCs. We found that the mRNAs and proteins of choline transporter-like protein 1 (CTL1) and CTL2 were expressed at high levels. Immunostaining showed that CTL1 and CTL2 were localized in the cell membrane and partly in the mitochondria, respectively. The uptake of extracellular choline was saturable and performed by a single uptake mechanism, which was Na-independent and pH-dependent. We conclude that CTL1 is responsible for extracellular choline uptake, and CTL2 may uptake choline in the mitochondria and be involved in DNA methylation via choline oxidation. Extracellular choline uptake inhibition caused intracellular choline deficiency in hNSCs, which suppressed cell proliferation, cell viability, and neurite outgrowth. Our findings contribute to the understanding of the role of choline in neural development as well as the pathogenesis of various neurological diseases caused by choline deficiency or choline uptake impairment.
胆碱及其代谢物是所有细胞功能的必需物质。它们也被报道对神经发育至关重要。在这项工作中，我们研究了人神经干细胞（hNSCs）中胆碱摄取系统的功能特征。此外，我们还研究了细胞外胆碱摄取抑制对 hNSCs 细胞活性的影响。我们发现，胆碱转运蛋白样蛋白 1（CTL1）和 CTL2 的 mRNA 和蛋白表达水平较高。免疫染色显示 CTL1 和 CTL2 分别定位于细胞膜和部分线粒体。细胞外胆碱的摄取是饱和的，由单一摄取机制完成，该机制不依赖于 Na+且依赖于 pH 值。我们得出结论，CTL1 负责细胞外胆碱的摄取，CTL2 可能在线粒体摄取胆碱，并通过胆碱氧化参与 DNA 甲基化。细胞外胆碱摄取抑制导致 hNSCs 内的细胞内胆碱缺乏，从而抑制细胞增殖、细胞活力和突起生长。我们的研究结果有助于理解胆碱在神经发育中的作用以及由于胆碱缺乏或胆碱摄取受损引起的各种神经疾病的发病机制。
