ORP5 localizes to ER-lipid droplet contacts and regulates the level of PI(4)P on lipid droplets.
J Cell Biol
; 219(1)2020 01 06.
Article
em En
| MEDLINE
| ID: mdl-31653673
ABSTRACT
Lipid droplets (LDs) are evolutionarily conserved organelles that play important roles in cellular metabolism. Each LD is enclosed by a monolayer of phospholipids, distinct from bilayer membranes. During LD biogenesis and growth, this monolayer of lipids expands by acquiring phospholipids from the endoplasmic reticulum (ER) through nonvesicular mechanisms. Here, in a mini-screen, we find that ORP5, an integral membrane protein of the ER, can localize to ER-LD contact sites upon oleate loading. ORP5 interacts with LDs through its ligand-binding domain, and ORP5 deficiency enhances neutral lipid synthesis and increases the size of LDs. Importantly, there is significantly more phosphatidylinositol-4-phosphate (PI(4)P) and less phosphatidylserine (PS) on LDs in ORP5-deficient cells than in normal cells. The increased presence of PI(4)P on LDs in ORP5-deficient cells requires phosphatidylinositol 4-kinase 2-α. Our results thus demonstrate the existence of PI(4)P on LDs and suggest that LD-associated PI(4)P may be primarily used by ORP5 to deliver PS to LDs.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Receptores de Esteroides
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Antígenos de Histocompatibilidade Menor
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Fosfotransferases (Aceptor do Grupo Álcool)
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Fosfatos de Fosfatidilinositol
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Proteínas de Transferência de Fosfolipídeos
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Retículo Endoplasmático
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Gotículas Lipídicas
Limite:
Humans
Idioma:
En
Revista:
J Cell Biol
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Austrália