Glutaminolysis Was Induced by TGF-β1 through PP2Ac Regulated Raf-MEK-ERK Signaling in Endothelial Cells.
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.
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
YanYan
Y
Guo
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
YuanJun
Y
Deng
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
XiaoQing
X
Li
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
Yong
Y
Ning
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
XuePing
X
Lin
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
ShuiMing
S
Guo
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
MeiXue
M
Chen
Department of Nephrology, Division of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Sicence and Technology, Wuhan, Hubei, China.
Min
M
Han
D002465:Cell Movement / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D005972:Glutaminase / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008954:Models, Biological; D019319:Okadaic Acid / Q000494:pharmacology; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D048490:raf Kinases / Q000378:metabolism*
D034741:RNA, Small Interfering; D053773:Transforming Growth Factor beta1; D005973:Glutamine; D019319:Okadaic Acid; D048490:raf Kinases; D054648:Protein Phosphatase 2; D005972:Glutaminase