Activation of AKT by O-linked N-acetylglucosamine induces vascular calcification in diabetes mellitus.
Activation of AKT by O-linked N-acetylglucosamine induces vascular calcification in diabetes mellitus.
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DOI：
10.1161/circresaha.114.302968
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发表时间：
2014-03-28
影响因子：
20.1
通讯作者：
Chen Y
中科院分区：
文献类型：
--
作者：
Heath JM;Sun Y;Yuan K;Bradley WE;Litovsky S;Dell'Italia LJ;Chatham JC;Wu H;Chen Y
血管钙化是一种严重的心血管并发症，导致糖尿病患者发病率和死亡率增加。高血压是糖尿病的标志，与血管钙化增加以及O-连接的N-乙酰葡糖胺（O-GlcNAc酰化）对蛋白质的修饰增加有关。我们试图确定蛋白质O-GlcNAc化在调节血管钙化中的作用及其潜在机制。低剂量链脲佐菌素诱导的糖尿病小鼠表现出主动脉O-GlcNAc化和血管钙化增加，这也与小鼠主动脉顺应性受损有关。Thiamet-G是一种有效的O-GlcNAc酶（OGA）抑制剂，可清除O-GlcNAc酰化，通过Thiamet-G给药导致O-GlcNAc酰化升高，进一步加速体内糖尿病小鼠的血管钙化和主动脉顺应性恶化。通过Thiamet-G或OGA敲除增加的O-GlcNAc化促进了原代小鼠血管平滑肌细胞（VSMC）的钙化。糖尿病动脉或OGA敲低VSMC中O-GlcNAc化的增加上调成骨转录因子Runx 2的表达并增强AKT的活化。AKT在两个新的O位点T430和T479的O-GlcNAc化促进了AKT磷酸化，这反过来又增强了VSMC钙化。AKT在T430和T479的定点突变降低了O-GlcNAc酰化，抑制了AKT在S473的磷酸化和mTOR复合物2与AKT的结合，随后阻断了Runx 2的反式活性和VSMC钙化。两个新位点的O-GlcNAc化增强了AKT的磷酸化和活化，从而促进了血管钙化。我们的研究已经确定了O-GlcNAc酰化在调节糖尿病血管钙化中的一种新的致病作用，并揭示了O-GlcNAc酰化介导的AKT激活的关键分子机制。
Vascular calcification is a serious cardiovascular complication that contributes to the increased morbidity and mortality of patients with diabetes. Hyperglycemia, a hallmark of diabetes, is associated with increased vascular calcification as well as increased modification of proteins by O-linked N-acetylglucosamine (O-GlcNAcylation). We sought to determine the role of protein O-GlcNAcylation in regulating vascular calcification and the underlying mechanisms. Low-dose streptozotocin-induced diabetic mice exhibited increased aortic O-GlcNAcylation and vascular calcification, which also was associated with impaired aortic compliance in mice. Elevation of O-GlcNAcylation by administration of Thiamet-G, a potent inhibitor for O-GlcNAcase (OGA) that removes O-GlcNAcylation, further accelerated vascular calcification and worsened aortic compliance of diabetic mice in vivo. Increased O-GlcNAcylation, either by Thiamet-G or OGA knockdown, promoted calcification of primary mouse vascular smooth muscle cells (VSMC). Increased O-GlcNAcylation in diabetic arteries or in the OGA knockdown VSMC upregulated expression of the osteogenic transcription factor Runx2 and enhanced activation of AKT. O-GlcNAcylation of AKT at two new O-sites, T430 and T479, promoted AKT phosphorylation, which in turn enhanced VSMC calcification. Site-directed mutation of AKT at T430 and T479 decreased O-GlcNAcylation, inhibited phosphorylation of AKT at S473 and binding of mTOR complex 2 to AKT, and subsequently blocked Runx2 transactivity and VSMC calcification. O-GlcNAcylation of AKT at two new sites enhanced AKT phosphorylation and activation, thus promoting vascular calcification. Our studies have identified a novel causative effect of O-GlcNAcylation in regulating vascular calcification in diabetes and uncovered a key molecular mechanism underlying O-GlcNAcylation-mediated activation of AKT.