Glutaminolysis Was Induced by TGF-β1 through PP2Ac Regulated Raf-MEK-ERK Signaling in Endothelial Cells
Glutaminolysis Was Induced by TGF-β1 through PP2Ac Regulated Raf-MEK-ERK Signaling in Endothelial Cells
复制标题
谷氨酰胺分解是由 TGF-β1 通过 PP2Ac 调节内皮细胞中的 Raf-MEK-ERK 信号传导诱导的
DOI：
10.1371/journal.pone.0162658
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发表时间：
2016-09-09
期刊：
影响因子：
3.7
通讯作者：
Han, Min
中科院分区：
文献类型：
--
作者：
Guo, YanYan;Deng, YuanJun;Han, Min
血管内皮细胞通过改变细胞能量代谢，可以在缺氧和炎症条件下存活。除了高速率的糖酵解，氨解是在这种情况下提供支持细胞发芽所需能量的另一种重要方式。然而，内皮细胞上调多巴胺分解的确切机制仍不清楚。在这里，我们证明了蛋白磷酸酶2A（PP 2A）介导的Raf-MEK-ERK信号参与内皮细胞中的精氨酸分解。利用转化生长因子-β1（transforming growth factor-β1，TGF-β1）处理的人脐静脉内皮细胞（human umbilical vein endothelial cells，HUVECs）模型，我们观察到细胞谷氨酸水平的显著诱导，伴随Raf-MEK-ERK激活。通过加入MEK 1/2的特异性抑制剂U 0126，肾型丙氨酸氨基转移酶（KGA，在丙氨酸氨基转移酶分解中的关键丙氨酸氨基转移酶）的表达显著降低。此外，通过冈田酸（OA）（PP 2A磷酸酶活性的特异性抑制剂）或通过耗尽其催化亚基（PP 2Ac）来抑制PP 2A，导致Raf-MEK-ERK信号传导的显著失活和内皮细胞中的精氨酸分解减少。综上所述，这些结果表明，PP 2A依赖性Raf-MEK-ERK活化参与了内皮细胞中的谷氨酰胺分解，并且抑制PP 2A信号足以阻断Raf-MEK-ERK途径并降低内皮细胞中的谷氨酰胺代谢。
Vascular endothelial cells can survive under hypoxic and inflammatory conditions by alterations of the cellular energy metabolism. In addition to high rates of glycolysis, glutaminolysis is another important way of providing the required energy to support cellular sprouting in such situations. However, the exact mechanism in which endothelial cells upregulate glutaminolysis remains unclear. Here we demonstrated that protein phosphatase 2A (PP2A)-mediated Raf-MEK-ERK signaling was involved in glutaminolysis in endothelial cells. Using models of human umbilical vein endothelial cells (HUVECs) treated with transforming growth factor-β1 (TGF-β1), we observed a dramatic induction in cellular glutamate levels accompanied by Raf-MEK-ERK activation. By addition of U0126, the specific inhibitor of MEK1/2, the expression of kidney-type glutaminase (KGA, a critical glutaminase in glutaminolysis) was significantly decreased. Moreover, inhibition of PP2A by okadaic acid (OA), a specific inhibitor of PP2A phosphatase activity or by depletion of its catalytic subunit (PP2Ac), led to a significant inactivation of Raf-MEK-ERK signaling and reduced glutaminolysis in endothelial cells. Taken together, these results indicated that PP2A-dependent Raf-MEK-ERK activation was involved in glutaminolysis and inhibition of PP2A signals was sufficient to block Raf-MEK-ERK pathway and reduced glutamine metabolism in endothelial cells.