Cellular cholesterol modifies flow-mediated gene expression
Cellular cholesterol modifies flow-mediated gene expression
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DOI：
10.1152/ajprenal.00196.2019
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发表时间：
2019-10-01
影响因子：
4.2
通讯作者：
Rohatgi, Rajeev
中科院分区：
文献类型：
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作者：
Repetti, Robert L.;Meth, Jennifer;Rohatgi, Rajeev
血红素加氧酶-1（HO-1）、环氧合酶-2（COX 2）和一氧化氮合酶-2（NOS 2）在达尔啮齿动物肾脏中的下调导致盐敏感性，而恢复它们的表达有助于Na+排泄和血压降低。将胆固醇装载到集合管（CD）细胞中抑制流体剪切应力（FSS）介导的COX 2活性。因此，我们假设，胆固醇抑制流反应基因必须实现钠+排泄。为此，CD细胞用于测试FSS是否诱导这些基因以及胆固醇负荷是否抑制它们。给喂食0%或1%胆固醇饲料的小鼠注射生理盐水，测量尿量和电解质，并测定肾脏基因表达。与静态培养的CD细胞相比，剪切后CD细胞HO-1、COX-2和NOS-2的mRNA表达分别增加了350倍、25倍和8倍（P < 0.01）。剪切细胞的免疫印迹分析显示HO-1，COX 2和NOS 2蛋白的增加，而条件培养基含有更多的HO-1和PGE 2比静态细胞。胆固醇负荷抑制剪切介导的HO-1和NOS 2蛋白丰度以及HO-1和PGE 2在培养基中的浓度。胆固醇组小鼠注射等渗盐水后6 h尿量减少（P < 0.05）。与对照组小鼠相比，在6 h尿收集时间点，胆固醇喂养小鼠的尿Na+浓度、尿K+浓度和渗透压均较高，而Na+排泄量较低（P < 0.05）。与对照组相比，高胆固醇组小鼠肾皮质和髓质HO-1（P < 0.05）和NOS 2（P < 0.05）mRNA表达受到抑制。胆固醇的作用是抑制血流诱导的利钠基因表达，这种作用在体内可能有助于肾Na+亲合力。
Downregulation of heme oxygenase-1 (HO-1), cyclooxygenase-2 (COX2), and nitric oxide synthase-2 (NOS2) in the kidneys of Dahl rodents causes salt sensitivity, while restoring their expression aids in Na+ excretion and blood pressure reduction. Loading cholesterol into collecting duct (CD) cells represses fluid shear stress (FSS)-mediated COX2 activity. Thus, we hypothesized that cholesterol represses flow-responsive genes necessary to effectuate Na+ excretion. To this end, CD cells were used to test whether FSS induces these genes and if cholesterol loading represses them. Mice fed either 0% or 1% cholesterol diet were injected with saline, urine volume and electrolytes were measured, and renal gene expression determined. FSS-exposed CD cells demonstrated increases in HO-1 mRNA by 350-fold, COX2 by 25-fold, and NOS2 by 8-fold in sheared cells compared with static cells (P < 0.01). Immunoblot analysis of sheared cells showed increases in HO-1, COX2, and NOS2 protein, whereas conditioned media contained more HO-1 and PGE2 than static cells. Cholesterol loading repressed the sheared mediated protein abundance of HO-1 and NOS2 as well as HO-1 and PGE2 concentrations in media. In cholesterol-fed mice, urine volume was less at 6 h after injection of isotonic saline (P < 0.05). Urinary Na+ concentration, urinary K+ concentration, and osmolality were greater, whereas Na+ excretion was less, at the 6-h urine collection time point in cholesterol-fed versus control mice (P < 0.05). Renal cortical and medullary HO-1 (P < 0.05) and NOS2 (P < 0.05) mRNA were repressed in cholesterol-fed compared with control mice. Cholesterol acts to repress flow induced natriuretic gene expression, and this effect, in vivo, may contribute to renal Na+ avidity.