Department of Medicine, Division of Nutritional Sciences, Washington University School of Medicine, St. Louis, MO, 63110, USA.
Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, VA, 22908, USA.
Nat Commun. 2023 Jul 7;14(1):4029. doi: 10.1038/s41467-023-39752-3.
Endothelial cell (EC) CD36 controls tissue fatty acid (FA) uptake. Here we examine how ECs transfer FAs. FA interaction with apical membrane CD36 induces Src phosphorylation of caveolin-1 tyrosine-14 (Cav-1Y14) and ceramide generation in caveolae. Ensuing fission of caveolae yields vesicles containing FAs, CD36 and ceramide that are secreted basolaterally as small (80-100 nm) exosome-like extracellular vesicles (sEVs). We visualize in transwells EC transfer of FAs in sEVs to underlying myotubes. In mice with EC-expression of the exosome marker emeraldGFP-CD63, muscle fibers accumulate circulating FAs in emGFP-labeled puncta. The FA-sEV pathway is mapped through its suppression by CD36 depletion, blocking actin-remodeling, Src inhibition, Cav-1Y14 mutation, and neutral sphingomyelinase 2 inhibition. Suppression of sEV formation in mice reduces muscle FA uptake, raises circulating FAs, which remain in blood vessels, and lowers glucose, mimicking prominent Cd36 mice phenotypes. The findings show that FA uptake influences membrane ceramide, endocytosis, and EC communication with parenchymal cells.
内皮细胞（EC）CD36 控制组织脂肪酸（FA）摄取。本文研究了 EC 如何转运 FA。FA 与顶膜 CD36 相互作用会诱导 caveolin-1 酪氨酸-14（Cav-1Y14）Src 磷酸化和小窝内鞘脂生成。随后小窝的裂变产生含有 FA、CD36 和鞘脂的囊泡，这些囊泡作为 80-100nm 的小（80-100nm）外泌体样细胞外囊泡（sEV）基底外侧分泌。我们在 Transwell 中可视化了 sEV 中 FA 在 EC 向下方肌管的转移。在 EC 表达外泌体标记物 emeraldGFP-CD63 的小鼠中，肌肉纤维在 emGFP 标记的斑点中积累循环 FA。通过 CD36 耗竭、阻断肌动蛋白重塑、Src 抑制、Cav-1Y14 突变和中性鞘磷脂酶 2 抑制来抑制 FA-sEV 途径。在小鼠中抑制 sEV 形成会减少肌肉 FA 摄取，增加循环 FA，使其留在血管中，并降低血糖，模拟 Cd36 小鼠的显著表型。研究结果表明，FA 摄取会影响膜鞘脂、内吞作用以及 EC 与实质细胞的通讯。
