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Purification of the Membrane Compartment for Endoplasmic Reticulum-associated Degradation of Exogenous Antigens in Cross-presentation
Published on: August 21, 2017
Role for LAMP-2 in endosomal cholesterol transport
Alexander Schneede1, Christine K Schmidt, Maarit Hölttä-Vuori
1Institute of Biochemistry, University of Kiel, Kiel, Germany.
Journal of Cellular and Molecular Medicine
|November 26, 2009
Summary
Lysosome-associated membrane protein-2 (LAMP-2) is crucial for cholesterol export from late endosomes and lysosomes. Deficiencies in LAMP-2 impair cholesterol transport, leading to its accumulation within these organelles.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Cholesterol homeostasis is vital for cellular function.
- Endosomal and lysosomal cholesterol transport mechanisms remain largely unelucidated.
- Lysosome-associated membrane proteins (LAMPs) are key components of late endosomes and lysosomes.
Purpose of the Study:
- To investigate the role of LAMP-1 and LAMP-2 in cellular cholesterol trafficking.
- To determine the specific contribution of LAMP-2 to cholesterol export from endosomes and lysosomes.
Main Methods:
- Utilized fibroblasts deficient in LAMP-1 and LAMP-2 (LAMP(-/-)) and wild-type cells.
- Assessed low-density lipoprotein (LDL) receptor levels and LDL uptake.
- Analyzed cholesterol esterification of endogenous and LDL-derived cholesterol.
- Examined cholesterol accumulation in LAMP-2 deficient liver.
- Investigated the effect of LAMP-2 overexpression on lysosomal cholesterol accumulation induced by U18666A.
- Studied the impact of LAMP-2 isoforms and domains on cholesterol transport.
Main Results:
- LAMP(-/-) cells exhibited increased LDL receptor levels and uptake but impaired cholesterol esterification.
- Cholesterol accumulated in LAMP-2 deficient liver cells.
- Overexpression of LAMP-2 reduced U18666A-induced lysosomal cholesterol accumulation.
- Specific isoforms and the luminal domain of LAMP-2 were sufficient to rescue cholesterol transport defects.
Conclusions:
- LAMP-2 plays a critical role in facilitating cholesterol export from late endosomes and lysosomes.
- This function of LAMP-2 in cholesterol transport is distinct from its role in chaperone-mediated autophagy.
- Defects in LAMP-2 impair cellular cholesterol homeostasis by disrupting endolysosomal cholesterol export.
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