TY - JOUR
T1 - The lipid moiety 7-ketocholesteryl-9-carboxynonanoate mediates binding interaction of oxLDL to LOX-1 and upregulates ABCA1 expression through PPARγ
AU - Li, Jingda
AU - Xiu, Zhilong
AU - Wang, Renjun
AU - Yu, Chengjie
AU - Chi, Yan
AU - Qin, Jianzhong
AU - Fu, Changzhen
AU - Matsuura, Eiji
AU - Liu, Qingping
N1 - Funding Information:
This work was supported by grants from the National Natural Science Foundation of China (No: 81270361, 30971232 and 81202536).
PY - 2017/5/15
Y1 - 2017/5/15
N2 - Aim Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), a specific membrane receptor for oxidized low-density lipoprotein (oxLDL), plays a crucial role in atherosclerosis progression. The aim of this study was to elucidate the role of 7-ketocholesteryl-9-carboxynonanoate (oxLig-1), a lipid component of oxLDL, in the binding of oxLDL to LOX-1 and to determine whether oxLig-1 binding to LOX-1 is involved in the upregulation of ABCA1 expression. Main methods OxLig-1 binding to LOX-1 was analysed by AutoDock 4.2.6 and confirmed by fluorescence immunocytochemistry and enzyme-linked immunosorbent assays (ELISAs). LOX-1, LXRα and ABCA1 protein expression induced by oxLig-1 or methylated oxLig-1 was measured by western blotting. In addition, PPARγ activation was investigated using a dual-luciferase reporter system. Furthermore, the signalling cascade involved in oxLig-1-induced ABCA1 expression was assessed using inhibitors for PPARγ and LXRα and specific siRNAs against LOX-1, PPARγ and LXRα. Key findings Docking, fluorescence immunocytochemistry and ELISA analyses showed that oxLig-1 bound LOX-1 and that the ω-carboxyl group was critical for this binding. Moreover, oxLig-1, but not methylated oxLig-1, increased LOX-1, LXRα, and ABCA1 expression. Luciferase reporter assays indicated that oxLig-1 activated PPARγ in the presence of LOX-1. Additionally, the inhibitor and siRNA experiments showed that oxLig-1 triggered the PPARγ-LXRα signalling pathway, leading to upregulation of ABCA1, and that this process required the participation of LOX-1. Significance Our observations indicate that oxLig-1 is a critical epitope of oxLDL that mediates the binding of oxLDL to LOX-1 and initiates PPARγ signal transduction to upregulate the expression of ABCA1.
AB - Aim Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), a specific membrane receptor for oxidized low-density lipoprotein (oxLDL), plays a crucial role in atherosclerosis progression. The aim of this study was to elucidate the role of 7-ketocholesteryl-9-carboxynonanoate (oxLig-1), a lipid component of oxLDL, in the binding of oxLDL to LOX-1 and to determine whether oxLig-1 binding to LOX-1 is involved in the upregulation of ABCA1 expression. Main methods OxLig-1 binding to LOX-1 was analysed by AutoDock 4.2.6 and confirmed by fluorescence immunocytochemistry and enzyme-linked immunosorbent assays (ELISAs). LOX-1, LXRα and ABCA1 protein expression induced by oxLig-1 or methylated oxLig-1 was measured by western blotting. In addition, PPARγ activation was investigated using a dual-luciferase reporter system. Furthermore, the signalling cascade involved in oxLig-1-induced ABCA1 expression was assessed using inhibitors for PPARγ and LXRα and specific siRNAs against LOX-1, PPARγ and LXRα. Key findings Docking, fluorescence immunocytochemistry and ELISA analyses showed that oxLig-1 bound LOX-1 and that the ω-carboxyl group was critical for this binding. Moreover, oxLig-1, but not methylated oxLig-1, increased LOX-1, LXRα, and ABCA1 expression. Luciferase reporter assays indicated that oxLig-1 activated PPARγ in the presence of LOX-1. Additionally, the inhibitor and siRNA experiments showed that oxLig-1 triggered the PPARγ-LXRα signalling pathway, leading to upregulation of ABCA1, and that this process required the participation of LOX-1. Significance Our observations indicate that oxLig-1 is a critical epitope of oxLDL that mediates the binding of oxLDL to LOX-1 and initiates PPARγ signal transduction to upregulate the expression of ABCA1.
KW - 7-Ketocholesteryl-9-carboxynonanoate
KW - ABCA1
KW - LOX-1
KW - Oxidized low-density lipoprotein
KW - PPARγ
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U2 - 10.1016/j.lfs.2017.03.024
DO - 10.1016/j.lfs.2017.03.024
M3 - Article
C2 - 28377266
AN - SCOPUS:85017476598
VL - 177
SP - 27
EP - 40
JO - Life Sciences
JF - Life Sciences
SN - 0024-3205
ER -