PT  - JOURNAL ARTICLE
AU  - Yan Li
AU  - Siwei Huang
AU  - Xuesong Li
AU  - Xingyu Yang
AU  - Ningyi Xu
AU  - Jianan Qu
AU  - Ho Yi Mak
TI  - The endoplasmic reticulum-resident protein TMEM-120/TMEM120A promotes fat storage in <em>C. elegans</em> and mammalian cells
AID  - 10.1101/2021.06.29.450322
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.06.29.450322
4099  - http://biorxiv.org/content/early/2021/06/29/2021.06.29.450322.short
4100  - http://biorxiv.org/content/early/2021/06/29/2021.06.29.450322.full
AB  - The synthesis of triacylglycerol (TAG) is essential for the storage of excess fatty acids, which can subsequently be used for energy or cell growth. A series of enzymes act in the endoplasmic reticulum (ER) to synthesize TAG, prior to its transfer to lipid droplets (LDs), which are conserved organelles for fat storage. Here, we report that the deficiency of TMEM-120/TMEM120A, a protein with 6-transmembrane helices, retards TAG synthesis and LD expansion in C. elegans. GFP fusion proteins of TMEM-120, expressed at the endogenous level in live worms, were observed throughout the ER network. Using Stimulated Raman Scattering, we demonstrated the specific requirement of TMEM-120 in the storage of exogenous fatty acids in LDs. Knockdown of TMEM120A impedes adipogenesis of pre-adipocytes in vitro, while its over-expression is sufficient to promote LD expansion in mammalian cells. Our results suggest that TMEM-120/TMEM120A plays a conserved role in increasing the efficiency of TAG synthesis.Competing Interest StatementThe authors have declared no competing interest.