中文摘要：

以乙酰辅酶A为原料的从头合成和小肠从食物中吸收是人体获得胆固醇的主要来源。胆固醇的内源合成在转录水平上受SREBP通路调控，在转录后水平上主要受胆固醇合成途径限速酶HMGCR和SM的降解调控。小肠对胆固醇吸收是一个涉及胆汁乳化、转运及酯化等多个步骤的复杂过程。定位于小肠上皮刷状缘膜上的Niemann．Pick C1 Like1（NPCIL1）是介导胆固醇吸收的关键蛋白，负责跨膜运输胆固醇进入小肠吸收细胞。现主要总结胆固醇合成途径的调控机制、NPCIL1蛋白介导胆固醇吸收的分子途径，以及讨论小肠胆固醇吸收与人体血液胆固醇水平之间的相关性。

英文摘要：

The humans obtain cholesterol through de novo synthesis from acety1-CoA and intestinal absorption from food. The de novo synthesis of cholesterol is regulated both transcriptionally by SREBP pathway and posttranscriptionally by the degradation of rate-controlling enzymes HMGCR. Intestinal cholesterol absorption is a complex process that involves multiple steps including emulsification by bile, transport and esterification. Niemann- Pick C 1 Like 1 （NPC IL1） residing on enterocyte brush border membrane, a key protein for cholesterol absorption, transports cholesterol into cells across plasma membrane. This review summarizes the regulation of cholesterol synthesis, the molecular mechanism whereby NPC1LI effectively and specifically transports cholesterol, and the correlation between intestinal cholesterol absorption and human blood cholesterol level.