Translational Metabolism Unit, Diabetes Research Center, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Baylor College of Medicine, Houston, TX, USA.
Department of Molecular Biology, University of Houston, Houston, TX, USA.
Sci Rep. 2017 Oct 17;7(1):13362. doi: 10.1038/s41598-017-13835-w.
HIV patients develop hepatic steatosis. We investigated hepatic steatosis in transgenic mice expressing the HIV-1 accessory protein Vpr (Vpr-Tg) in liver and adipose tissues, and WT mice infused with synthetic Vpr. Vpr-Tg mice developed increased liver triglyceride content and elevated ALT, bilirubin and alkaline phosphatase due to three hepatic defects: 1.6-fold accelerated de novo lipogenesis (DNL), 45% slower fatty acid ß-oxidation, and 40% decreased VLDL-triglyceride export. Accelerated hepatic DNL was due to coactivation by Vpr of liver X receptor-α (LXRα) with increased expression of its lipogenic targets Srebp1c, Chrebp, Lpk, Dgat, Fasn and Scd1, and intranuclear SREBP1c and ChREBP. Vpr enhanced association of LXRα with Lxrα and Srebp1c promoters, increased LXRE-LXRα binding, and broadly altered hepatic expression of LXRα-regulated lipid metabolic genes. Diminished hepatic fatty acid ß-oxidation was associated with decreased mRNA expression of Pparα and its targets Cpt1, Aox, Lcad, Ehhadh, Hsd10 and Acaa2, and blunted VLDL export with decreased expression of Mttp and its product microsomal triglyceride transfer protein. With our previous findings that Vpr circulates in HIV patients (including those with undetectable plasma HIV-1 RNA), co-regulates the glucocorticoid receptor and PPARγ and transduces hepatocytes, these data indicate a potential role for Vpr in HIV-associated fatty liver disease.
HIV 患者会发生肝脂肪变性。我们研究了在肝和脂肪组织中表达 HIV-1 辅助蛋白 Vpr(Vpr-Tg)的转基因小鼠以及输注合成 Vpr 的 WT 小鼠中的肝脂肪变性。Vpr-Tg 小鼠由于三种肝缺陷而导致肝甘油三酯含量增加和 ALT、胆红素和碱性磷酸酶升高:1.6 倍加速从头合成(DNL),45%脂肪酸β-氧化减慢,40%VLDL-甘油三酯输出减少。加速的肝 DNL 是由于 Vpr 与 LXRα 的共激活,导致其脂生成靶标 Srebp1c、Chrebp、Lpk、Dgat、Fasn 和 Scd1 的表达增加,以及核内 SREBP1c 和 ChREBP 的表达增加。Vpr 增强了 LXRα 与 Lxrα 和 Srebp1c 启动子的结合,增加了 LXRE-LXRα 结合,并广泛改变了 LXRα 调节的脂质代谢基因在肝中的表达。肝脂肪酸β-氧化减少与 Pparα 和其靶基因 Cpt1、Aox、Lcad、Ehhadh、Hsd10 和 Acaa2 的 mRNA 表达减少有关,VLDL 输出减少与 Mttp 及其产物微粒体甘油三酯转移蛋白的表达减少有关。鉴于我们之前的发现,Vpr 在 HIV 患者(包括那些血浆 HIV-1 RNA 检测不到的患者)中循环,共同调节糖皮质激素受体和 PPARγ,并转导肝细胞,这些数据表明 Vpr 在 HIV 相关脂肪性肝病中可能具有作用。