| 1. |
- Feng, Yue Hua, et al.
(author)
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Increased apolipoprotein M induced by lack of scavenger receptor BI is not activated via HDL-mediated cholesterol uptake in hepatocytes
- 2018
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In: Lipids in Health and Disease. - : Springer Science and Business Media LLC. - 1476-511X. ; 17:1
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Journal article (peer-reviewed)abstract
- Background: Scavenger receptor BI (SR-BI) is a classic high-density lipoprotein (HDL) receptor, which mediates selective lipid uptake from HDL cholesterol esters (HDL-C). Apolipoprotein M (ApoM), as a component of HDL particles, could influence preβ-HDL formation and cholesterol efflux. The aim of this study was to determine whether SR-BI deficiency influenced the expression of ApoM. Methods: Blood samples and liver tissues were collected from SR-BI gene knockout mice, and serum lipid parameters, including total cholesterol (TC), triglyceride (TG), high and low-density lipoprotein cholesterol (HDL-C and LDL-C) and ApoM were measured. Hepatic ApoM and ApoAI mRNA levels were also determined. In addition, BLT-1, an inhibitor of SR-BI, was added to HepG2 cells cultured with cholesterol and HDL, under serum or serum-free conditions. The mRNA and protein expression levels of ApoM were detected by RT-PCR and western blot. Results: We found that increased serum ApoM protein levels corresponded with high hepatic ApoM mRNA levels in both male and female SR-BI-/- mice. Besides, serum TC and HDL-C were also significantly increased. Treatment of HepG2 hepatoma cells with SR-BI specific inhibitor, BLT-1, could up-regulate ApoM expression in serum-containing medium but not in serum-free medium, even in the presence of HDL-C and cholesterol. Conclusions: Results suggested that SR-BI deficiency promoted ApoM expression, but the increased ApoM might be independent from HDL-mediated cholesterol uptake in hepatocytes.
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| 2. |
- Zhu, Bin, et al.
(author)
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Apolipoprotein M Protects Against Lipopolysaccharide-Induced Acute Lung Injury via Sphingosine-1-Phosphate Signaling
- 2018
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In: Inflammation. - : Springer Science and Business Media LLC. - 0360-3997 .- 1573-2576. ; 41:2, s. 643-653
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Journal article (peer-reviewed)abstract
- Abstract: It had been demonstrated that apolipoprotein M (apoM) is an important carrier of sphingosine-1-phosphate (S1P) in blood, and the S1P has critical roles in the pathogenesis of sepsis-induced acute lung injury (ALI). In the present study, we investigated whether apoM has beneficial effects in a mouse model after lipopolysaccharide (LPS)-induced ALI. Forty-eight mice were divided into two groups: male C57BL/6 wild-type (apoM+/+) group (n = 24) and apoM gene-deficient (apoM−/−) group (n = 24) and then randomly subdivided into four subgroups (n = 6 each) according to different intraperitoneal (i.p.) injection: control group, W146 group, LPS group, and LPS + W146 group. Serum levels of interleukin-1 beta (IL-1β) and mRNA levels of IL-1β, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), lung histology, wet/dry weight ratio, and immunohistochemistry were measured at 3 h after the baseline and compared in each group. Our results clearly demonstrated that IL-1β mRNA levels and other inflammatory biomarkers were significantly increased in the lungs of LPS-induced ALI apoM−/− mice compared to those of the apoM+/+ mice. Moreover, when apoM+/+ mice were treated with W146, a S1P receptor (S1PR1) antagonist, these inflammatory biomarkers could be significantly upregulated by LPS-induced ALI. Therefore, it suggests that apoM-S1P-S1PR1 signaling might underlie the pathogenesis of ALI and apoM could have physiological benefits to alleviate LPS-induced ALI.
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