Niemann-Pick C1 Like 1 (NPC1L1) is known to be involved in the intestinal absorption of cholesterol. For evaluating the function of NPC1L1, cell lines such as Caco-2, Madin-Darby canine kidney (MDCK) II, and McA-RH7777 have been used in previous studies, but the detailed molecular mechanism of transport has not been elucidated. In this study, the characteristics of cholesterol transport via NPC1L1 were investigated using a Xenopus laevis oocyte expression system in addition to a conventional cell line with stable expression. The transport activity of cholesterol uptake was increased in NPC1L1-overexpressed MDCK cells compared with that in mock cells, but MDCK cells expressed endogenous NPC1L1 and had high cholesterol transport activity. On the other hand, cRNA-injected oocytes expressed NPC1L1 after culturing for 5–6 days. The transport activity of cholesterol uptake was increased in NPC1L1 cRNA-injected oocytes compared with that in water-injected oocytes. In addition, the uptake of cholesterol was decreased in the presence of ezetimibe, an NPC1L1 inhibitor, in cRNA-injected oocytes but not in control oocytes, indicating that endogenous NPC1L1 is not expressed in oocytes. Furthermore, cholesterol uptake was substantially decreased in NPC1L1 L216A cRNA-injected oocytes compared with that in NPC1L1 cRNA-injected oocytes, indicating that leucine at position 216 of NPC1L1 is important for cholesterol transport and that an oocyte expression system is useful for mutant analysis. These results indicate that the oocyte expression system is useful for evaluating the characteristics of NPC1L1-mediated cholesterol transport and may contribute to the elucidation of the detailed molecular mechanism of cholesterol transport via NPC1L1.

Niemann-Pick C1 Like 1（NPC1L1）被认为与胆固醇的肠道吸收有关。为了评估NPC1L1的功能，以前的研究中已经使用了细胞系，例如Caco-2，Madin-Darby犬肾（MDCK）II和McA-RH7777，但尚未阐明其详细的运输分子机制。在这项研究中，使用非洲爪蟾调查了胆固醇通过NPC1L1转运的特征。卵母细胞表达系统除具有稳定表达的常规细胞系外。与模拟细胞相比，在过表达NPC1L1的MDCK细胞中胆固醇摄取的运输活性增加，但是MDCK细胞表达内源性NPC1L1，并且具有高胆固醇运输活性。另一方面，培养5-6天后，注射cRNA的卵母细胞表达NPC1L1。与注水的卵母细胞相比，NPC1L1 cRNA注入的卵母细胞胆固醇吸收的转运活性增加。此外，在注射了cRNA的卵母细胞中，在NPC1L1抑制剂依泽替米贝存在下胆固醇的吸收降低了，但在对照卵母细胞中却没有，这表明卵母细胞中不表达内源性NPC1L1。此外，与NPC1L1 cRNA注射的卵母细胞相比，NPC1L1 L216A cRNA注射的卵母细胞中的胆固醇摄取显着降低，这表明NPC1L1 216位的亮氨酸对于胆固醇转运很重要，并且卵母细胞表达系统可用于突变分析。这些结果表明，卵母细胞表达系统可用于评估NPC1L1介导的胆固醇转运的特性，并且可能有助于阐明通过NPC1L1转运胆固醇的详细分子机制。