Most organs use fatty acids (FAs) as a key nutrient, but little is known of how blood-borne FAs traverse the endothelium to reach underlying tissues. We conducted a small-molecule screen and identified niclosamide as a suppressor of endothelial FA uptake and transport. Structure/activity relationship studies demonstrated that niclosamide acts through mitochondrial uncoupling. Inhibitors of oxidative phosphorylation and the ATP/ADP translocase also suppressed FA uptake, pointing principally to ATP production. Decreasing total cellular ATP by blocking glycolysis did not decrease uptake, indicating that specifically mitochondrial ATP is required. Endothelial FA uptake is promoted by fatty acid transport protein 4 (FATP4) via its ATP-dependent acyl-CoA synthetase activity. Confocal microscopy revealed that FATP4 resides in the endoplasmic reticulum (ER), and that endothelial ER is intimately juxtaposed with mitochondria. Together, these data indicate that mitochondrial ATP production, but not total ATP levels, drives endothelial FA uptake and transport via acyl-CoA formation in mitochondrial/ER microdomains.

大多数器官都使用脂肪酸 (FA) 作为关键营养素，但人们对血源性 FA 如何穿过内皮到达底层组织知之甚少。我们进行了小分子筛选，确定氯硝柳胺是内皮 FA 摄取和转运的抑制剂。结构/活性关系研究表明氯硝柳胺通过线粒体解偶联发挥作用。氧化磷酸化抑制剂和 ATP/ADP 转位酶也抑制 FA 的摄取，主要指向 ATP 的产生。通过阻断糖酵解来减少总细胞 ATP 并不会减少摄取，表明需要专门的线粒体 ATP。脂肪酸转运蛋白 4 (FATP4) 通过其 ATP 依赖性酰基辅酶 A 合成酶活性促进内皮 FA 摄取。共聚焦显微镜显示 FATP4 存在于内质网 (ER) 中，并且内皮 ER 与线粒体紧密相邻。总之，这些数据表明，线粒体 ATP 的产生（而非总 ATP 水平）通过线粒体/ER 微域中酰基辅酶 A 的形成驱动内皮 FA 的摄取和运输。