Gao Guangang, Sheng Yuanyuan, Yang Hongyuan, Chua Boon Tin, Xu Li
State Key Laboratory of Membrane Biology and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084, Beijing, China.
School of Biotechnology and Biomolecular Sciences, University of New South Wales, 2052 New South Wales, Sydney, Australia.
Cell Biol Int. 2019 Dec;43(12):1492-1504. doi: 10.1002/cbin.11199. Epub 2019 Jul 23.
Double FYVE-containing protein 1 (DFCP1) is ubiquitously expressed, participates in intracellular membrane trafficking and labels omegasomes through specific interactions with phosphatidylinositol-3-phosphate (PI3P). Previous studies showed that subcellular DFCP1 proteins display multi-organelle localization, including in the endoplasmic reticulum (ER), Golgi apparatus and mitochondria. However, its localization and function on lipid droplets (LDs) remain unclear. Here, we demonstrate that DFCP1 localizes to the LD upon oleic acid incubation. The ER-targeted domain of DFCP1 is indispensable for its LD localization, which is further enhanced by double FYVE domains. Inhibition of PI3P binding at the FYVE domain through wortmannin treatment or double mutation at C654S and C770S have no effect on DFCP1's LD localization. These show that the mechanisms for DFCP1 targeting the omegasome and LDs are different. DFCP1 deficiency in MEF cells causes an increase in LD number and reduces LD size. Interestingly, DFCP1 interacts with GTP-bound Rab18, an LD-associated protein. Taken together, our work demonstrates the dynamic localization of DFCP1 is regulated by nutritional status in response to cellular metabolism.
含双FYVE结构域蛋白1（DFCP1）广泛表达，参与细胞内膜运输，并通过与磷脂酰肌醇-3-磷酸（PI3P）的特异性相互作用标记ω小体。先前的研究表明，亚细胞DFCP1蛋白表现出多细胞器定位，包括在内质网（ER）、高尔基体和线粒体中。然而，其在脂滴（LDs）上的定位和功能仍不清楚。在此，我们证明油酸孵育后DFCP1定位于脂滴。DFCP1的内质网靶向结构域对其脂滴定位不可或缺，双FYVE结构域进一步增强了这种定位。通过渥曼青霉素处理或C654S和C770S双突变抑制FYVE结构域处的PI3P结合对DFCP1的脂滴定位没有影响。这些表明DFCP1靶向ω小体和脂滴的机制不同。MEF细胞中DFCP1的缺失导致脂滴数量增加并减小脂滴大小。有趣的是，DFCP1与GTP结合的Rab18相互作用，Rab18是一种与脂滴相关的蛋白。综上所述，我们的工作表明DFCP1的动态定位受营养状态调节以响应细胞代谢。
