Cyclin-dependent kinase 5 phosphorylates serine 31 of tyrosine hydroxylase and regulates its stability
Cyclin-dependent kinase 5 phosphorylates serine 31 of tyrosine hydroxylase and regulates its stability
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DOI：
10.1074/jbc.m406636200
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发表时间：
2004-12-24
影响因子：
4.8
通讯作者：
Tsai, LH
中科院分区：
文献类型：
--
作者：
Moy, LY;Tsai, LH
酪氨酸羟化酶（TH）是儿茶酚胺生物合成中的限速酶，其活性受N端调节域磷酸化的调节。脯氨酸导向的丝氨酸/苏氨酸激酶细胞周期蛋白依赖性激酶 5 (cdk5) 在多种神经元过程中发挥着重要作用。在本研究中，我们将 TH 确定为 cdk5 的新型底物。我们发现 cdk5 在丝氨酸 31 处磷酸化 TH，并且这种磷酸化与总 TH 活性的增加相关。在 cdk5 活性增加的转基因小鼠中，黑质神经元（富含 TH 阳性神经元的大脑区域）的 Ser-31 位点磷酸化 TH 的免疫反应性增强。此外，我们证明cdk5及其调节激活剂p35与TH的共表达增加了TH的稳定性。与这些发现一致的是，cdk5 敲除小鼠中 TH 蛋白水平降低。重要的是，磷酸化缺陷突变体 TH S31A 的 TH 活性和蛋白质周转率并未因 cdk5 活性而改变。总而言之，这些数据表明 TH 的 cdk5 磷酸化是通过稳定 TH 蛋白水平来调节 TH 活性的重要因素。
Tyrosine hydroxylase (TH) is the rate-limiting enzyme in catecholamine biosynthesis, and its activity is regulated by phosphorylation in the N-terminal regulatory domain. The proline-directed serine/threonine kinase cyclin-dependent kinase 5 (cdk5) plays an important role in diverse neuronal processes. In the present study, we identify TH as a novel substrate of cdk5. We show that cdk5 phosphorylates TH at serine 31 and that this phosphorylation is associated with an increase in total TH activity. In transgenic mice with increased cdk5 activity, the immunoreactivity for phosphorylated TH at Ser-31 is enhanced in neurons of the substantia nigra, a brain region enriched with TH-positive neurons. In addition, we demonstrate that co-expression of cdk5 and its regulatory activator p35 with TH increases the stability of TH. Consistent with these findings, TH protein levels are reduced in cdk5 knock-out mice. Importantly, the TH activity and protein turnover of the phosphorylation-defective mutant TH S31A was not altered by cdk5 activity. Taken together, these data suggest that cdk5 phosphorylation of TH is an important regulator of TH activity through stabilization of TH protein levels.