V-ATPase (Vacuolar ATPase) Activity Required for ABCA1 (ATP-Binding Cassette Protein A1)-Mediated Cholesterol Efflux
| العنوان: | V-ATPase (Vacuolar ATPase) Activity Required for ABCA1 (ATP-Binding Cassette Protein A1)-Mediated Cholesterol Efflux |
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| المؤلفون: | Gregory Brubaker, Jonathan D. Smith, Kailash Gulshan, Shuhui Wang Lorkowski |
| المصدر: | Arteriosclerosis, Thrombosis, and Vascular Biology. 38:2615-2625 |
| بيانات النشر: | Ovid Technologies (Wolters Kluwer Health), 2018. |
| سنة النشر: | 2018 |
| مصطلحات موضوعية: | 0301 basic medicine, biology, Chemistry, Cholesterol, Bafilomycin, 030204 cardiovascular system & hematology, Cell membrane, 03 medical and health sciences, chemistry.chemical_compound, 030104 developmental biology, 0302 clinical medicine, medicine.anatomical_structure, ABCA1, Baby hamster kidney cell, biology.protein, medicine, Biophysics, V-ATPase, lipids (amino acids, peptides, and proteins), Efflux, Cardiology and Cardiovascular Medicine, Fluorescein isothiocyanate |
| الوصف: | Objective— We have shown that ABCA1 (ATP-binding cassette protein A1) mediates unfolding of the apoA1 (apolipoprotein A1) N-terminal helical hairpin during apoA1 lipidation. Others have shown that an acidic pH exposes the hydrophobic surface of apoA1. We postulated that the V-ATPase (vacuolar ATPase) proton pump facilitates apoA1 unfolding and promotes ABCA1-mediated cholesterol efflux. Approach and Results— We found that V-ATPase inhibitors dose-dependently decreased ABCA1-mediated cholesterol efflux to apoA1 in baby hamster kidney cells and RAW264.7 cells; and similarly, siRNA knockdown of ATP6V 0 C inhibited ABCA1-mediated cholesterol efflux to apoA1 in RAW264.7 cells. Although ABCA1 expression did not alter total cellular levels of V-ATPase, ABCA1 increased the cell surface levels of the V 0 A1 and V 1 E1 subunits of V-ATPase. We generated a fluorescein isothiocyanate/Alexa647 double-labeled fluorescent ratiometric apoA1 pH indicator whose fluorescein isothiocyanate/Alexa647 emission ratio decreased as the pH drops. We found that ABCA1 induction in baby hamster kidney cells led to acidification of the cell-associated apoA1 pH indicator, compared with control cells without ABCA1 expression. The V-ATPase inhibitor bafilomycin A1 dose-dependently inhibited the apoA1 pH shift in ABCA1-expressing cells, without affecting the levels of cell-associated apoA1. However, we were not able to detect ABCA1-mediated extracellular proton release. We showed that acidic pH facilitated apoA1 unfolding, apoA1 solubilization of phosphatidycholine:phosphatidyserine liposomes, and increased lipid fluidity of these liposomes. Conclusions— Our results support a model that ABCA1 recruits V-ATPase to the plasma membrane where V-ATPase mediates apoA1 acidification and membrane remodeling that promote apoA1 unfolding and ABCA1-mediated HDL (high-density lipoprotein) biogenesis and lipid efflux. |
| تدمد: | 1524-4636 1079-5642 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_________::f0d7aac953c7fa9287e0c3cc06aa14bbTest https://doi.org/10.1161/atvbaha.118.311814Test |
| حقوق: | OPEN |
| رقم الانضمام: | edsair.doi...........f0d7aac953c7fa9287e0c3cc06aa14bb |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 15244636 10795642 |
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