Seipin is required for converting nascent to mature lipid droplets - Wang, Huajin and Becuwe, Michel and Housden, Benjamin E. and Chitraju, Chandramohan and Porras, Ashley J. and Graham, Morven M. and Liu, Xinran N. and Thiam, Abdou Rachid and Savage, David B. and Agarwal, Anil K. and Garg, Abhimanyu and Olarte, Maria-Jesus and Lin, Qingqing and Froehlich, Florian and Hannibal-Bach, Hans Kristian and Upadhyayula, Srigokul and Perrimon, Norbert and Kirchhausen, Tomas and Ejsing, Christer S. and Walther, Tobias C. and Farese, Jr., Robert V.
ELIFE 5, (2016)
Abstract : How proteins control the biogenesis of cellular lipid droplets (LDs) is
poorly understood. Using Drosophila and human cells, we show here that
seipin, an ER protein implicated in LD biology, mediates a discrete step
in LD formation-the conversion of small, nascent LDs to larger, mature
LDs. Seipin forms discrete and dynamic foci in the ER that interact with
nascent LDs to enable their growth. In the absence of seipin, numerous
small, nascent LDs accumulate near the ER and most often fail to grow.
Those that do grow prematurely acquire lipid synthesis enzymes and
undergo expansion, eventually leading to the giant LDs characteristic of
seipin deficiency. Our studies identify a discrete step of LD formation,
namely the conversion of nascent LDs to mature LDs, and define a
molecular role for seipin in this process, most likely by acting at
ER-LD contact sites to enable lipid transfer to nascent LDs.