Endogenous sterol intermediates of the mevalonate pathway regulate HMGCR degradation and SREBP-2 processing[S]
Endogenous sterol intermediates of the mevalonate pathway regulate HMGCR degradation and SREBP-2 processing[S]
复制标题
甲羟戊酸途径的内源性甾醇中间体调节 HMGCR 降解和 SREBP-2 加工
DOI：
10.1194/jlr.ra119000201
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发表时间：
2019-10-01
影响因子：
6.5
通讯作者：
Song, Bao-Liang
中科院分区：
文献类型：
--
作者：
Chen, Liang;Ma, Mei-Yan;Song, Bao-Liang
甾醇调节的HMG-CoA还原酶（HMGCR）降解和SREBP-2裂解是控制胆固醇生物合成的两种主要反馈调节机制。据报道，羊毛甾醇选择性刺激HMGCR降解，胆固醇是SREBP-2裂解的特异性调节剂。然而，目前还不清楚是否有其他内源性产生的甾醇调节这些事件。在这里，我们使用CRISPR/Cas9介导的基因工程方法研究了胆固醇生物合成的甲羟戊酸途径中的甾醇中间体。构建的HeLa细胞系表达甲羟戊酸转运蛋白，我们单独删除编码甲羟戊酸途径中主要酶的基因，使用脂质组学测量甾醇中间体，并检查HMGCR和SREBP-2状态。我们发现，C4-二甲基甾醇中间体，包括羊毛甾醇，24，25-二氢羊毛甾醇，卵泡液减数分裂激活甾醇，睾丸减数分裂激活甾醇，和二氢睾丸减数分裂激活甾醇，甲羟戊酸加载后显着上调。这些中间体增强了HMGCR的降解和SREBP-2切割的抑制。积累的羊毛甾醇诱导HMGCR的快速降解，但不抑制SREBP-2裂解。来自甲羟戊酸途径的新合成的胆固醇被认为抑制SREBP-2裂解。总之，这些结果表明，羊毛甾醇是一种真正的内源性调节剂，特异性地促进HMGCR降解，其他C4-二甲基甾醇中间体可以调节HMGCR降解和SREBP-2裂解。
Sterol-regulated HMG-CoA reductase (HMGCR) degradation and SREBP-2 cleavage are two major feedback regulatory mechanisms governing cholesterol biosynthesis. Reportedly, lanosterol selectively stimulates HMGCR degradation, and cholesterol is a specific regulator of SREBP-2 cleavage. However, it is unclear whether other endogenously generated sterols regulate these events. Here, we investigated the sterol intermediates from the mevalonate pathway of cholesterol biosynthesis using a CRISPR/Cas9-mediated genetic engineering approach. With a constructed HeLa cell line expressing the mevalonate transporter, we individually deleted genes encoding major enzymes in the mevalonate pathway, used lipidomics to measure sterol intermediates, and examined HMGCR and SREBP-2 statuses. We found that the C4-dimethylated sterol intermediates, including lanosterol, 24,25-dihydrolanosterol, follicular fluid meiosis activating sterol, testis meiosis activating sterol, and dihydro-testis meiosis activating sterol, were significantly upregulated upon mevalonate loading. These intermediates augmented both degradation of HMGCR and inhibition of SREBP-2 cleavage. The accumulated lanosterol induced rapid degradation of HMGCR, but did not inhibit SREBP-2 cleavage. The newly synthesized cholesterol from the mevalonate pathway is dispensable for inhibiting SREBP-2 cleavage. Together, these results suggest that lanosterol is a bona fide endogenous regulator that specifically promotes HMGCR degradation, and that other C4-dimethylated sterol intermediates may regulate both HMGCR degradation and SREBP-2 cleavage.