人体从胆汁和食物中吸收大量胆固醇，Niemann-Pick C1-like 1(NPC1L1) 是该过程中的关键蛋白。为了进一步在体内环境下研究NPC1L1介导饮食胆固醇吸收的分子机制，我们利用能特异性识别小鼠内源NPC1L1蛋白的多克隆抗体从小肠上皮吸收细胞中通过免疫共沉淀结合蛋白质谱技术筛选得到了一系列潜在的与NPC1L1相互作用的候选蛋白。又通过在细胞上的共定位实验，RNAi实验以及CRISPR/Cas9技术对候选蛋白进行二次筛选和验证，发现Dennd4c蛋白很有可能在NPC1L1介导的小肠胆固醇吸收过程发挥重要作用。鉴于Dennd4c在受胰岛素刺激的Glut4介导的葡萄糖吸收过程中发挥重要作用，我们发现胰岛素信号也能够调控细胞内NPC1L1的定位和功能，提示NPC1L1介导的胆固醇吸收过程很有可能是受胰岛素信号调控的。本项目将深入研究该过程中的分子调控机制。

Dietary absorption is a major way for mammals to obtain cholesterol, which is mediated by Niemann-Pick C1-like 1 (NPC1L1) via vesicular endocytosis. To further study the function and mechanism of NPC1L1 in vivo, I made a high-quality antibody which specifically recognizes mouse NPC1L1 protein. By using this antibody, I performed Co-IP and mass spectrometry assay in mouse intestinal enterocytes, and found a series of candidate proteins that may participate in the process of NPC1L1-mediated cholesterol absorption. These candidates were next validated by analyzing their co-localization with NPC1L1, and knockdown assays using RNAi and CRISPR/Cas9 technology. At last, Dennd4c and insulin signal were suggested to play an important role in NPC1L1-mediated cholesterol absorption.