Oxysterols are 27-carbon oxidized derivatives of cholesterol or by-products of cholesterol biosynthesis that can induce cell apoptosis in addition to a number of other bioactions. However, the mechanisms underlying this cytotoxicity are not completely understood. ORP8 is a member of the oxysterol binding protein-related protein (ORP) family, implicated in cellular lipid homeostasis, migration, and organization of the microtubule cytoskeleton. Here, we report that 25-hydroxycholesterol (OHC) induced apoptosis of the hepatoma cell lines, HepG2 and Huh7, via the endoplasmic reticulum (ER) stress response pathway, and ORP8 overexpression resulted in a similar cell response as 25- OHC, indicating a putative functional relationship between oxysterol cytotoxicity and ORP8. Further experiments demonstrated that ORP8 overexpression significantly enhanced the 25-OHC effect on ER stress and apoptosis in HepG2 cells. A truncated ORP8 construct lacking the ligand-binding domain or a closely related protein, ORP5, was devoid of this activity, evidencing for specificity of the observed effects. Importantly, ORP8 knockdown markedly dampened such responses to 25-OHC. Taken together, the present study suggests that ORP8 may mediate the cytotoxicity of 25-OHC.-Li, J., X. Zheng, N. Lou, W. Zhong, and D. Yan. Oxysterol binding protein-related protein 8 mediates the cytotoxicity of 25-hydroxycholesterol.
CITATION STYLE
Li, J., Zheng, X., Lou, N., Zhong, W., & Yan, D. (2016). Oxysterol binding protein-related protein 8 mediates the cytotoxicity of 25-hydroxycholesterol. Journal of Lipid Research, 57(10), 1845–1853. https://doi.org/10.1194/jlr.M069906
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