NPC1 regulates the distribution of phosphatidylinositol 4‐kinases at Golgi and lysosomal membranes

• Published in: The EMBO journal 2021-07, Vol.40 (13), p.e105990-n/a
• Main Authors: Kutchukian, Candice, Vivas, Oscar, Casas, Maria, Jones, Julia G, Tiscione, Scott A, Simó, Sergi, Ory, Daniel S, Dixon, Rose E, Dickson, Eamonn J
• Format: Article
• Language: English
• Subjects: Acyltransferase; Animals; Biological Transport - physiology; Cell Line; Cell Membrane - metabolism; Cell membranes; CHO Cells; Cholesterol; Cholesterol - metabolism; Cricetulus; Egress; EMBO20; EMBO57; Endoplasmic reticulum; Endoplasmic Reticulum - metabolism; Golgi apparatus; Golgi Apparatus - metabolism; HEK293 Cells; Humans; Intracellular; Intracellular Membranes - metabolism; Intracellular Signaling Peptides and Proteins - metabolism; Intracellular signalling; Kinases; Lipids; Lysosomes; Lysosomes - metabolism; Male; Mammalian cells; Mechanistic Target of Rapamycin Complex 1 - metabolism; membrane contact sites; Membrane Glycoproteins - metabolism; Membranes; Mice; mTORC; Mutation; neurodegeneration; Niemann-Pick C1 Protein - metabolism; Niemann‐Pick Type C; Npc1 protein; Phosphatidylinositol Phosphates - metabolism; Phosphoinositides; Recruitment; Secretion; Signal Transduction - physiology; Signaling
• ISSN: 0261-4189; 1460-2075; 1460-2075
• DOI: 10.15252/embj.2020105990

Cholesterol and phosphoinositides (PI) are two critically important lipids that are found in cellular membranes and dysregulated in many disorders. Therefore, uncovering molecular pathways connecting these essential lipids may offer new therapeutic insights. We report that loss of function of lysosomal Niemann‐Pick Type C1 (NPC1) cholesterol transporter, which leads to neurodegenerative NPC disease, initiates a signaling cascade that alters the cholesterol/phosphatidylinositol 4‐phosphate (PtdIns4P) countertransport cycle between Golgi‐endoplasmic reticulum (ER), as well as lysosome‐ER membrane contact sites (MCS). Central to these disruptions is increased recruitment of phosphatidylinositol 4‐kinases—PI4KIIα and PI4KIIIβ—which boosts PtdIns4P metabolism at Golgi and lysosomal membranes. Aberrantly increased PtdIns4P levels elevate constitutive anterograde secretion from the Golgi complex, and mTORC1 recruitment to lysosomes. NPC1 disease mutations phenocopy the transporter loss of function and can be rescued by inhibition or knockdown of either key phosphoinositide enzymes or their recruiting partners. In summary, we show that the lysosomal NPC1 cholesterol transporter tunes the molecular content of Golgi and lysosome MCS to regulate intracellular trafficking and growth signaling in health and disease. Synopsis The lysosomal Niemann‐Pick Type C1 (NPC1) transporter is essential for the egress of cholesterol from the lysosome to other cellular membranes. This study shows that NPC1 tunes the composition of Golgi‐endoplasmic reticulum (ER) and lysosome‐ER membrane contact sites (MCS) to regulate intracellular trafficking and growth signaling in mammalian cells. Phosphatidylinositol 4‐phosphate (PtdIns4P) levels are increased at Golgi and lysosomal membranes in NPC1 patient‐derived cells and in the brain of an NPC1 mouse model. High levels of PtdIns4P are due to increased recruitment of PI4KIIα and PI4KIIIβ kinases at Golgi and lysosomal membranes. Palmitoyl acyltransferase DHHC3 and multi‐functional adaptor protein ACBD3 mediate recruitment of PI4KIIα and PI4KIIIβ to Golgi‐ER and lysosome‐ER MCS. PtdIns4P increases anterograde secretion from the Golgi, and mTORC1 recruitment to lysosomes. Graphical Abstract The lysosomal Niemann‐Pick Type C1 cholesterol transporter tunes the composition of Golgi‐ER and lysosome‐ER membrane contact sites to regulate intracellular trafficking and growth signaling in mammalian cells.