Phosphorylation of tau at THR212 and SER214 in human neuronal and glial cultures: The role of Akt
Phosphorylation of tau at THR212 and SER214 in human neuronal and glial cultures: The role of Akt
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DOI：
10.1016/j.neuroscience.2004.05.036
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发表时间：
2004-01-01
期刊：
影响因子：
3.3
通讯作者：
Ksiezak-Reding, H
中科院分区：
文献类型：
--
作者：
Pyo, HK;Lovati, E;Ksiezak-Reding, H
我们最近报道了微管相关蛋白tau在体外被Akt磷酸化，Akt是胰岛素和生长因子调节的抗凋亡信号的重要激酶。我们还发现Akt分别在T212和S214位点磷酸化tau蛋白，这两个位点先前分别被糖原合成酶激酶3 β (gsk3 β)和蛋白激酶A （PKA）磷酸化。在本研究中，我们在人神经元和星形胶质细胞原代培养中检测了Akt和T212/S214之间的关系，并评估了另外两种激酶的作用。在完整细胞中，我们发现活性（phospho-S473）形式的Akt含量非常低。我们还发现tau蛋白的phospho-S214含量较低，而phospho-T212含量不高，这表明只有phospho-S212可能依赖于Akt的原位活性。我们使用两种实验模型上调Akt的活性：用蛋白磷酸酶抑制剂冈田酸处理和转染组成型活性Akt基因构建体（c-Akt）。在这些条件下，T212和S214位点的tau磷酸化被独立调控，phospho-T212几乎没有变化或下调，而phospho-S214则动态上调。我们的研究表明Akt可能以有意义的方式影响phospho-S214的含量。他们还发现PKA可能仅部分参与S214的磷酸化。相比之下，冈田酸处理严重减少了gsk3 β的含量，并通过akt依赖性抑制下调了剩余的gsk3 β活性，与磷酸化- t212的微小变化一致。总之，这些结果强烈表明，在原代培养中，Akt选择性地磷酸化tau蛋白的S214位点而不是T212位点。我们的研究提出了tau S214可能参与akt介导的抗凋亡信号传导的可能性。(c) 2004 ibro。Elsevier Ltd.出版。版权所有。
We have reported recently that the microtubule-associated protein tau is phosphorylated in vitro by Akt, an important kinase in anti-apoptotic signaling regulated by insulin and growth factors. We also established that Akt phosphorylates tau separately at T212 and S214, two sites previously shown to be phosphorylated by glycogen synthase kinase 3beta (GSK3beta) and protein kinase A (PKA), respectively. In the present studies, we examined the relationship between Akt and T212/S214 in primary cultures of human neurons and astrocytes, and evaluated the contribution of two other kinases. In intact cells, we found a very low content of active (phospho-S473) form of Akt. We also found a low content of phospho-S214 but not phospho-T212 of tau, suggesting that only phospho-S212 may depend on Akt activity in situ. We upregulated Akt activity using two experimental models: treatment with a protein phosphatase inhibitor, okadaic acid, and transfection with a constitutively active Akt gene construct (c-Akt). Under these conditions, phosphorylation of tau at T212 and S214 was regulated independently, with little change or downregulation of phospho-T212 and dynamic upregulation of phospho-S214. Our studies revealed that Akt may influence the phospho-S214 content in a meaningful manner. They also revealed that PKA may only partially contribute to the phosphorylation of S214. In comparison, okadaic acid treatment severely depleted the content of GSK3beta and downregulated the remaining GSK3beta activity by Akt-dependent inhibition, consistent with minimal changes in phospho-T212. In summary, these results strongly suggest that in primary cultures, Akt selectively phosphorylates tau at S214 rather than T212. Our studies raise the possibility that tau S214 may participate in Akt-mediated anti-apoptotic signaling. (C) 2004 IBRO. Published by Elsevier Ltd. All rights reserved.