Role of Increased Guanosine Triphosphate Cyclohydrolase-1 Expression and Tetrahydrobiopterin Levels upon T Cell Activation
Role of Increased Guanosine Triphosphate Cyclohydrolase-1 Expression and Tetrahydrobiopterin Levels upon T Cell Activation
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DOI：
10.1074/jbc.m110.191023
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发表时间：
2011-04-22
影响因子：
4.8
通讯作者：
Harrison, David G.
中科院分区：
文献类型：
--
作者：
Chen, Wei;Li, Li;Harrison, David G.
四氢生物蝶呤（BH 4）是一氧化氮（NO）还原酶的重要辅助因子，在其缺乏时，这些酶产生超氧阴离子（O（2）自由基阴离子）而不是NO。BH 4产生的限速酶是鸟苷三磷酸环化水解酶-1（GTPCH-1）。由于内源性产生的NO影响T细胞功能，我们试图确定抗原刺激是否影响T细胞GTPCH-1表达和最终BH 4水平。静息T细胞具有最小的诱导型NOS（NOS 2）、内皮型NOS（NOS 3）和GTPCH-1蛋白表达，并且几乎检测不到BH 4水平。T细胞的抗CD 3刺激强烈刺激了NOS 2、NOS 3和GTPCH-1的协调表达，并显著增加了GTPCH-1活性和T细胞BH 4水平。新表达的GTPCH-1在丝氨酸72上被磷酸化，酪蛋白激酶II的药理学抑制降低了GTPCH-1的磷酸化并减弱了T细胞BH 4的增加。用二氨基羟基嘧啶（1 mmol/L）抑制GTPCH-1可防止T细胞BH 4蓄积，减少NO产生，并增加T细胞O（2）自由基阴离子。生产，由于NOS 2和NOS 3解偶联。GTPCH-1抑制还促进记忆性CD 4细胞中的TH 2极化。卵清蛋白受体转基因小鼠（OT-II小鼠）的卵清蛋白免疫证实了体内T细胞BH 4的显著增加。这些研究确定了一个以前未确定的T细胞活化的结果，促进BH 4水平，NO的产生，并调节T细胞细胞因子的产生。
Tetrahydrobiopterin (BH4) is an essential co-factor for the nitric-oxide (NO) synthases, and in its absence these enzymes produce superoxide (O(2)radical anion) rather than NO. The rate-limiting enzyme for BH4 production is guanosine triphosphate cyclohydrolase-1 (GTPCH-1). Because endogenously produced NO affects T cell function, we sought to determine whether antigen stimulation affected T cell GTPCH-1 expression and ultimately BH4 levels. Resting T cells had minimal expression of inducible NOS (NOS2), endothelial NOS (NOS3), and GTPCH-1 protein and nearly undetectable levels of BH4. Anti-CD3 stimulation of T cells robustly stimulated the coordinated expression of NOS2, NOS3, and GTPCH-1 and markedly increased both GTPCH-1 activity and T cell BH4 levels. The newly expressed GTPCH-1 was phosphorylated on serine 72 and pharmacological inhibition of casein kinase II reduced GTPCH-1 phosphorylation and blunted the increase in T cell BH4. Inhibition of GTPCH-1 with diaminohydroxypyrimidine (1 mmol/liter) prevented T cell BH4 accumulation, reduced NO production, and increased T cell O(2)radical anion. production, due to both NOS2 and NOS3 uncoupling. GTPCH-1 inhibition also promoted TH2 polarization in memory CD4 cells. Ovalbumin immunization of mice transgenic for an ovalbumin receptor (OT-II mice) confirmed a marked increase in T cell BH4 in vivo. These studies identify a previously unidentified consequence of T cell activation, promoting BH4 levels, NO production, and modulating T cell cytokine production.