Role of STARD4 in sterol transport between the endocytic recycling compartment and the plasma membrane
| Autor: | David B. Iaea, Shu Mao, Frederik W. Lund, Frederick R. Maxfield |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
Endosome Kinetics Endocytic recycling STARD4 Endosomes Biology 03 medical and health sciences Cell Line Tumor Ergosterol polycyclic compounds Fluorescence microscope Animals Humans Molecular Biology Sheep Cell Membrane Membrane Transport Proteins Biological Transport Articles Cell Biology Compartment (chemistry) Sterol transport Endocytosis 3. Good health Sterols Cholesterol 030104 developmental biology Membrane Membrane Trafficking Biophysics lipids (amino acids peptides and proteins) |
| Zdroj: | Molecular Biology of the Cell |
| ISSN: | 1939-4586 1059-1524 |
| DOI: | 10.1091/mbc.e16-07-0499 |
| Popis: | The kinetics of sterol transport between the plasma membrane and the endocytic recycling compartment is measured using fluorescence microscopy. STARD4, a small, soluble sterol transport protein, is responsible for 25% of the total transport and 33% of nonvesicular transport. Elevated cholesterol dramatically increases sterol transport rate constants. Cholesterol is an essential constituent of membranes in mammalian cells. The plasma membrane and the endocytic recycling compartment (ERC) are both highly enriched in cholesterol. The abundance and distribution of cholesterol among organelles are tightly controlled by a combination of mechanisms involving vesicular and nonvesicular sterol transport processes. Using the fluorescent cholesterol analogue dehydroergosterol, we examined sterol transport between the plasma membrane and the ERC using fluorescence recovery after photobleaching and a novel sterol efflux assay. We found that sterol transport between these organelles in a U2OS cell line has a t1/2 =12–15 min. Approximately 70% of sterol transport is ATP independent and therefore is nonvesicular. Increasing cellular cholesterol levels dramatically increases bidirectional transport rate constants, but decreases in cholesterol levels have only a modest effect. A soluble sterol transport protein, STARD4, accounts for ∼25% of total sterol transport and ∼33% of nonvesicular sterol transport between the plasma membrane and ERC. This study shows that nonvesicular sterol transport mechanisms and STARD4 in particular account for a large fraction of sterol transport between the plasma membrane and the ERC. |
| Databáze: | OpenAIRE |
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