title: Fsp27 promotes lipid droplet growth by lipid exchange and transfer at lipid droplet contact sites.
abstract: Lipid droplets (LDs) are dynamic cellular organelles that control many biological processes. However, molecular components determining LD growth are poorly understood. Genetic analysis has indicated that Fsp27, an LD-associated protein, is important in controlling LD size and lipid storage in adipocytes. In this paper, we demonstrate that Fsp27 is focally enriched at the LD-LD contacting site (LDCS). Photobleaching revealed the occurrence of lipid exchange between contacted LDs in wild-type adipocytes and Fsp27-overexpressing cells but not Fsp27-deficient adipocytes. Furthermore, live-cell imaging revealed a unique Fsp27-mediated LD growth process involving a directional net lipid transfer from the smaller to larger LDs at LDCSs, which is in accordance with the biophysical analysis of the internal pressure difference between the contacting LD pair. Thus, we have uncovered a novel molecular mechanism of LD growth mediated by Fsp27.
authors.affiliation: Peking-Tsinghua Center for Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Jingyi
authors.initials: J
authors.lastname: Gong
authors.forename: Zhiqi
authors.initials: Z
authors.lastname: Sun
authors.forename: Lizhen
authors.initials: L
authors.lastname: Wu
authors.forename: Wenyi
authors.initials: W
authors.lastname: Xu
authors.forename: Nicole
authors.initials: N
authors.lastname: Schieber
authors.forename: Dijin
authors.initials: D
authors.lastname: Xu
authors.forename: Guanghou
authors.initials: G
authors.lastname: Shui
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Yang
authors.forename: Robert G
authors.initials: RG
authors.lastname: Parton
authors.forename: Peng
authors.initials: P
authors.lastname: Li
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000378:metabolism*; D000818:Animals; D057809:HEK293 Cells; D006801:Humans; D050356:Lipid Metabolism; D051379:Mice; D015388:Organelles / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D011506:Proteins; C525805:fat-specific protein 27, mouse