151. Rab18 promotes lipid droplet (LD) growth by tethering the ER to LDs through SNARE and NRZ interactions
- Author
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Hongyuan Yang, Charles Ferguson, Jinhai Yu, Tuozhi Huang, Peng Li, Yuqi Li, Lizhen Wu, Dongyu Zhao, Dijin Xu, Ying Li, and Robert G. Parton
- Subjects
0301 basic medicine ,Biology ,Endoplasmic Reticulum ,Article ,Mice ,03 medical and health sciences ,3T3-L1 Cells ,Lipid droplet ,Animals ,Research Articles ,Endoplasmic reticulum ,USE1 ,Lipid Droplets ,Cell Biology ,3. Good health ,Cell biology ,030104 developmental biology ,rab GTP-Binding Proteins ,Unfolded protein response ,lipids (amino acids, peptides, and proteins) ,Rab ,SNARE Proteins ,SNARE complex ,Intracellular ,RAB18 - Abstract
Lipid incorporation from the ER to lipid droplets (LDs) influences LD growth and intracellular lipid homeostasis. Xu et al. identify Rab18 as an important regulator of LD dynamics: activated Rab18 binds to ER-associated proteins such as the NRZ complex and SNAREs. The Rab18-NRZ-SNARE complex tethers LDs to the ER, facilitating lipid incorporation and LD growth., Lipid incorporation from endoplasmic reticulum (ER) to lipid droplet (LD) is important in controlling LD growth and intracellular lipid homeostasis. However, the molecular link mediating ER and LD cross talk remains elusive. Here, we identified Rab18 as an important Rab guanosine triphosphatase in controlling LD growth and maturation. Rab18 deficiency resulted in a drastically reduced number of mature LDs and decreased lipid storage, and was accompanied by increased ER stress. Rab3GAP1/2, the GEF of Rab18, promoted LD growth by activating and targeting Rab18 to LDs. LD-associated Rab18 bound specifically to the ER-associated NAG-RINT1-ZW10 (NRZ) tethering complex and their associated SNAREs (Syntaxin18, Use1, BNIP1), resulting in the recruitment of ER to LD and the formation of direct ER–LD contact. Cells with defects in the NRZ/SNARE complex function showed reduced LD growth and lipid storage. Overall, our data reveal that the Rab18-NRZ-SNARE complex is critical protein machinery for tethering ER–LD and establishing ER–LD contact to promote LD growth.
- Published
- 2018