Endosomal cholesterol trafficking: protein factors at a glance

Ximing Du and Hongyuan Yang

Acta Biochim Biophys Sin (Shanghai). 2013 Jan;45(1):11-7. doi: 10.1093/abbs/gms095

School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia

The delivery of low-density lipoprotein-derived cholesterol (LDL-C) from endosomal compartments to the plasma membrane and the endoplasmic reticulum (ER) is an important yet poorly understood cellular process. Niemann-Pick C1 (NPC1), a multi-pass integral membrane protein on the limiting membranes of late endosomes (LE)/lysosomes (Ly), is known to insert lumenal LDL-C to the limiting membrane of LE/Ly. Recent progress has identified novel cytoplasmic proteins that regulate the exit of LDL-C from LE/Ly, such as ORP5, a member of the oxysterol-binding protein-related protein (ORPs) family, and Hrs/VPS27, a well-established regulator of the endosomal sorting complex required for transport pathway. Whereas ORP5/ORPs may serve as cytosolic cholesterol carriers and deliver cholesterol in a non-vesicular manner, how Hrs/VPS27 regulate endosomal cholesterol sorting remains enigmatic. We discuss the functional relationship between NPC1, Hrs, and ORP5, and formulate possible schemes on how LDL-C may be moved from endosomal compartments to other cellular organelles.

图例: 依赖于NPC1/ORP5/VPS4的低密度脂蛋白胆固醇(LDL-C)内质网膜运输模型

全文: http://abbs.oxfordjournals.org/content/45/1/11.full

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