title: Cholesterol requirement for cation-independent mannose 6-phosphate receptor exit from multivesicular late endosomes to the Golgi.
abstract: The regulation of endocytic traffic of receptors has central importance in the fine tuning of cell activities. Here, we provide evidence that cholesterol is required for the exit of cation-independent mannose 6-phosphate receptor (CI-MPR) from the endosomal carrier vesicle/multivesicular bodies (ECV/MVBs) to the Golgi. A previously established Chinese hamster ovary cell mutant, LEX2, exhibits arrested ECV/MVBs in which CI-MPR and lysosomal glycoprotein-B (lgp-B) are accumulated. The abnormal accumulation of CI-MPR within the ECV/MVBs in LEX2 cells was corrected in a post-translational manner by the supplementation of medium with cholesterol. Furthermore, it was shown that, by expression cloning using LEX2 mutant, the introduction of the NAD(P)H steroid dehydrogenase-like protein, an enzyme involved in the later stage of cholesterol biosynthesis, allows the exit of CI-MPR from the MVBs to the Golgi and reduces the number of arrested ECV/MVBs in LEX2 cells. The recovery of the exit transport of CI-MPR from the ECV/MVBs was associated with the restoration of the normal cellular free cholesterol level and segregation between CI-MPR and lgp-B, both of which had been localized at the internal small vesicles of the arrested ECV/MVBs. By contrast, the restoration of cholesterol failed to correct the defective processing of endocytosed LDL to a degradative compartment in LEX2 cells. These results suggest that cholesterol is required for ECV/MVB reorganization that drives the sorting/transport of materials destined for the Golgi out of the pathways towards lysosomes.
authors: Dept of Molecular Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan.
authors: I
authors: I
authors: Miwako
authors: A
authors: A
authors: Yamamoto
authors: T
authors: T
authors: Kitamura
authors: K
authors: K
authors: Nagayama
authors: M
authors: M
authors: Ohashi
mesh_terms: D000818:Animals; D016466:CHO Cells; D002412:Cations; D002784:Cholesterol / Q000378:metabolism*; D006224:Cricetinae; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism; D008856:Microscopy, Fluorescence; D017527:Receptor, IGF Type 2 / Q000378:metabolism*
chemical_list: D002412:Cations; D008077:Lipoproteins, LDL; D017527:Receptor, IGF Type 2; D002784:Cholesterol