Department of Physiology, University of Kentucky, Lexington, Kentucky, USA.
Veterans Affairs Medical Center, Lexington, Kentucky, USA.
J Extracell Vesicles. 2022 Jun;11(6):e12233. doi: 10.1002/jev2.12233.
The formation of extracellular vesicles (EVs) is induced by the sphingolipid ceramide. How this pathway is regulated is not entirely understood. Here, we report that the ceramide transport protein (CERT) mediates a non-vesicular transport of ceramide between the endoplasmic reticulum (ER) and the multivesicular endosome at contact sites. The process depends on the interaction of CERT's PH domain with PI4P generated by PI4KIIα at endosomes. Furthermore, a complex is formed between the START domain of CERT, which carries ceramide, and the Tsg101 protein, which is part of the endosomal sorting complex required for transport (ESCRT-I). Inhibition of ceramide biosynthesis reduces CERT-Tsg101 complex formation. Overexpression of CERT increases EV secretion while its inhibition reduces EV formation and the concentration of ceramides and sphingomyelins in EVs. In conclusion, we discovered a function of CERT in regulating the sphingolipid composition and biogenesis of EVs, which links ceramide to the ESCRT-dependent pathway.
细胞外囊泡（EVs）的形成是由神经酰胺诱导的。这条途径是如何被调节的还不完全清楚。在这里，我们报告称，神经酰胺转运蛋白（CERT）在 ER 和多泡体内涵体之间的接触部位介导神经酰胺的非囊泡运输。该过程依赖于 CERT 的 PH 结构域与内体中由 PI4KIIα 产生的 PI4P 的相互作用。此外，CERT 的 START 结构域与 Tsg101 蛋白形成复合物，CERT 携带神经酰胺，而 Tsg101 蛋白是参与运输所需的内体分选复合物（ESCRT-I）的一部分。神经酰胺生物合成的抑制减少了 CERT-Tsg101 复合物的形成。CERT 的过表达增加了 EV 的分泌，而其抑制减少了 EV 的形成以及 EV 中神经酰胺和神经鞘磷脂的浓度。总之，我们发现了 CERT 在调节 EV 中鞘脂组成和生物发生中的作用，将神经酰胺与 ESCRT 依赖途径联系起来。
