Role of Niemann-Pick Type C1 Protein in Intracellular Trafficking of Low Density Lipoprotein-derived Cholesterol

Cruz, Jonathan C.; Sugii, Shigeki; Yu, Chunjiang; Chang, Ta−Yuan

doi:10.1074/jbc.275.6.4013

Cited by 169 publications

(187 citation statements)

References 38 publications

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“…25RA cells contain a mutation in the sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP), which constitutively activates SREBP processing in a sterol-independent manner (18). CT43 cells are NPC1-null cells derived from 25RA cells (19). Findings made in this cell system are generally applicable to other cell types (8,(20)(21)(22).…”

Section: Nocodazole or Brefeldin A (Bfa) Affects The Re-esterificatiomentioning

confidence: 99%

Transport of LDL-derived cholesterol from the NPC1 compartment to the ER involves the trans-Golgi network and the SNARE protein complex

Urano

Watanabe

Murphy

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

105

131

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Mammalian cells acquire cholesterol mainly from LDL. LDL enter the endosomes, allowing cholesteryl esters to be hydrolyzed by acid lipase. The hydrolyzed cholesterol (LDL-CHOL) enters the Niemann–Pick type C1 (NPC1)-containing endosomal compartment en route to various destinations. Whether the Golgi is involved in LDL-CHOL transport downstream of the NPC1 compartment has not been demonstrated. Using subcellular fractionation and immunoadsorption to enrich for specific membrane fractions, here we show that, when parental Chinese hamster ovary (CHO) cells are briefly exposed to 3 H-cholesteryl linoleate (CL) labeled-LDL, newly liberated 3 H-LDL-CHOL appears in membranes rich in trans-Golgi network (TGN) long before it becomes available for re-esterification at the endoplasmic reticulum (ER) or for efflux at the plasma membrane. In mutant cells lacking NPC1, the appearance of newly liberated 3 H-LDL-CHOL in the TGN-rich fractions is much reduced. We next report a reconstituted transport system that recapitulates the transport of LDL-CHOL to the TGN and to the ER. The transport system requires ATP and cytosolic factors and depends on functionality of NPC1. We demonstrate that knockdown by RNAi of 3 TGN-specific SNAREs (VAMP4, syntaxin 6, and syntaxin 16) reduces ≥50% of the LDL-CHOL transport in intact cells and in vitro. These results show that vesicular trafficking is involved in transporting a significant portion of LDL-CHOL from the NPC1-containing endosomal compartment to the TGN before its arrival at the ER.

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Section: Nocodazole or Brefeldin A (Bfa) Affects The Re-esterificatiomentioning

confidence: 99%

Transport of LDL-derived cholesterol from the NPC1 compartment to the ER involves the trans-Golgi network and the SNARE protein complex

Urano

Watanabe

Murphy

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

105

131

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“…10). However, treatment of the wild-type embryonic fibroblasts with progesterone (50 g/ ml) caused the formation of filipin-laden lysosomes, demonstrating that a pharmacological manipulation known to produce a phenocopy of the Niemann-Pick type C sterol trafficking defect could be detected (data not shown) (23). When cells were stained with Nile Red to analyze the distribution of neutral lipids, no differences were observed between wild-type and knockout cells (Fig.…”

Section: Histochemical Analysis Of Hepatic Neutral Lipid Distributionmentioning

confidence: 82%

Targeted Mutation of the MLN64 START Domain Causes Only Modest Alterations in Cellular Sterol Metabolism

Kishida

Kostetskii

Zhang

et al. 2004

Journal of Biological Chemistry

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The StAR-related lipid transfer (START) domain, first identified in the steroidogenic acute regulatory protein (StAR), is involved in the intracellular trafficking of lipids. Sixteen mammalian START domain-containing proteins have been identified to date. StAR, a protein targeted to mitochondria, stimulates the movement of cholesterol from the outer to the inner mitochondrial membranes, where it is metabolized into pregnenolone in steroidogenic cells. MLN64, the START domain protein most closely related to StAR, is localized to late endosomes along with other proteins involved in sterol trafficking, including NPC1 and NPC2, where it has been postulated to participate in sterol distribution to intracellular membranes. To investigate the role of MLN64 in sterol metabolism, we created mice with a targeted mutation in the Mln64 START domain, expecting to find a phenotype similar to that in humans and mice lacking NPC1 or NPC2 (progressive neurodegenerative symptoms, free cholesterol accumulation in lysosomes). Unexpectedly, mice homozygous for the Mln64 mutant allele were viable, neurologically intact, and fertile. No significant alterations in plasma lipid levels, liver lipid content and distribution, and expression of genes involved in sterol metabolism were observed, except for an increase in sterol ester storage in mutant mice fed a high fat diet. Embryonic fibroblast cells transfected with the cholesterol side-chain cleavage system and primary cultures of granulosa cells from Mln64 mutant mice showed defects in sterol trafficking as reflected in reduced conversion of endogenous cholesterol to steroid hormones. These observations suggest that the Mln64 START domain is largely dispensable for sterol metabolism in mice.

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“…Expression of NPC1 in CHO (CT-60) Cells or Null NPC1 Human NP-C Fibroblasts-Functional expression of the plasmids pNNE and pNES-6 was confirmed by complementation of the NP-C phenotype in both CT-60 NP-C mutant CHO cells (20) or null NPC1 human NP-C fibroblasts. CT-60 cells and 93.41 primary skin fibroblasts from an NP-C patient were cultured to ϳ70% confluence.…”

Section: Methodsmentioning

confidence: 95%

Sterol-modulated Glycolipid Sorting Occurs in Niemann-Pick C1 Late Endosomes

Zhang¹,

Dwyer²,

Neufeld³

et al. 2001

Journal of Biological Chemistry

105

115

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The Niemann-Pick C1 (NPC1) protein and endocytosed low density lipoprotein (LDL)-derived cholesterol were shown to enrich separate subsets of vesicles containing lysosomal associated membrane protein 2. Localization of Rab7 in the NPC1-containing vesicles and enrichment of lysosomal hydrolases in the cholesterolcontaining vesicles confirmed that these organelles were late endosomes and lysosomes, respectively. Lysobisphosphatidic acid, a lipid marker of the late endosomal pathway, was found in the cholesterol-enriched lysosomes. Recruitment of NPC1 to Rab7 compartments was stimulated by cellular uptake of cholesterol. The NPC1 compartment was shown to be enriched in glycolipids, and internalization of GalNAc␤1-4[NeuAc␣2-3]Gal␤1-4Glc␤1-1-ceramide (G M2 ) into endocytic vesicles depends on the presence of NPC1 protein. The glycolipid profiles of the NPC1 compartment could be modulated by LDL uptake and accumulation of lysosomal cholesterol. Expression in cells of biologically active NPC1 protein fused to green fluorescent protein revealed rapidly moving and flexible tubular extensions emanating from the NPC1-containing vesicles. We conclude that the NPC1 compartment is a dynamic, sterolmodulated sorting organelle involved in the trafficking of plasma membrane-derived glycolipids as well as plasma membrane and endocytosed LDL cholesterol.

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Role of Niemann-Pick Type C1 Protein in Intracellular Trafficking of Low Density Lipoprotein-derived Cholesterol

Cited by 169 publications

References 38 publications

Transport of LDL-derived cholesterol from the NPC1 compartment to the ER involves the trans-Golgi network and the SNARE protein complex

Transport of LDL-derived cholesterol from the NPC1 compartment to the ER involves the trans-Golgi network and the SNARE protein complex

Targeted Mutation of the MLN64 START Domain Causes Only Modest Alterations in Cellular Sterol Metabolism

Sterol-modulated Glycolipid Sorting Occurs in Niemann-Pick C1 Late Endosomes

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