Conditional disruption of the peroxisome proliferator-activated receptor γ gene in mice results in lowered expression of ABCA1, ABCG1, and apoE in macrophages and reduced cholesterol efflux
Conditional disruption of the peroxisome proliferator-activated receptor γ gene in mice results in lowered expression of ABCA1, ABCG1, and apoE in macrophages and reduced cholesterol efflux
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DOI：
10.1128/mcb.22.8.2607-2619.2002
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发表时间：
2002-04-01
影响因子：
5.3
通讯作者：
Gonzalez, FJ
中科院分区：
文献类型：
--
作者：
Akiyama, TE;Sakai, S;Gonzalez, FJ
过氧化物酶体增殖物激活受体γ（PPARγ）基因的破坏会导致胎盘功能障碍导致胚胎死亡。为了解决这个问题，我们利用 Cre-loxP 系统制备了 PPARgamma 条件基因敲除小鼠。目标等位基因包含 PPARgamma 基因外显子 2 侧翼的 loxP 位点，与在 α/β 干扰素诱导型 (MX) 启动子控制下表达 Cre 重组酶的转基因小鼠系杂交。 pIpC 诱导 MX 启动子导致目标外显子几乎完全缺失，全长 PPARgamma mRNA 转录物和蛋白质相应丢失，并且在巯基乙酸引发的腹膜巨噬细胞中编码脂蛋白脂肪酶、CD36、LXRα 和 ABCG1 的基因的基础和曲格列酮刺激的表达显着减少。在 pIpC 处理的 PPARgamma-MXCre(+) 小鼠中还观察到巨噬细胞中载脂蛋白 E (apoE) mRNA 的基础水平以及总血浆和高密度脂蛋白 (HDL) 中的 apoE 蛋白的基础水平降低。 PPARgamma 基因破坏后，基础胆固醇从负载胆固醇的巨噬细胞向 HDL 的流出显着减少。曲格列酮选择性抑制 PPARγ 缺陷型巨噬细胞和对照巨噬细胞中的 ABCA1 表达（而罗格列酮、西格列酮和吡格列酮几乎没有影响）和胆固醇流出，表明该药物可以对独立于 PPARγ 的胆固醇稳态产生矛盾的影响。总之，这些数据表明 PPARgamma 通过控制介导胆固醇从细胞流出及其在血浆中运输的基因网络的表达，在胆固醇稳态的调节中发挥着关键作用。
Disruption of the peroxisome proliferator-activated receptor gamma (PPARgamma) gene causes embryonic lethality due to placental dysfunction. To circumvent this, a PPARgamma conditional gene knockout mouse was produced by using the Cre-loxP system. The targeted allele, containing loxP sites flanking exon 2 of the PPARgamma gene, was crossed into a transgenic mouse line expressing Cre recombinase under the control of the alpha/beta interferon-inducible (MX) promoter. Induction of the MX promoter by pIpC resulted in nearly complete deletion of the targeted exon, a corresponding loss of full-length PPARgamma mRNA transcript and protein, and marked reductions in basal and troglitazone-stimulated expression of the genes encoding lipoprotein lipase, CD36, LXRalpha, and ABCG1 in thioglycolate-elicited peritoneal macrophages. Reductions in the basal levels of apolipoprotein E (apoE) mRNA in macrophages and apoE protein in total plasma and high-density lipoprotein (HDL) were also observed in pIpC-treated PPARgamma-MXCre(+) mice. Basal cholesterol efflux from cholesterol-loaded macrophages to HDL was significantly reduced after disruption of the PPARgamma gene. Troglitazone selectively inhibited ABCA1 expression (while rosiglitazone, ciglitazone, and pioglitazone had little effect) and cholesterol efflux in both PPARgamma-deficient and control macrophages, indicating that this drug can exert paradoxical effects on cholesterol homeostasis that are independent of PPARgamma. Together, these data indicate that PPARgamma plays a critical role in the regulation of cholesterol homeostasis by controlling the expression of a network of genes that mediate cholesterol efflux from cells and its transport in plasma.