Regulation and function of glycogen synthase kinase-3 isoforms in neuronal survival
Regulation and function of glycogen synthase kinase-3 isoforms in neuronal survival
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DOI：
10.1074/jbc.m605178200
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发表时间：
2007-02-09
影响因子：
4.8
通讯作者：
Chuang, De-Maw
中科院分区：
文献类型：
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作者：
Liang, Min-Huei;Chuang, De-Maw
糖原合成酶激酶-3（GSK-3）是由两种同种型α和β组成的丝氨酸/苏氨酸激酶。GSK-3的活性受丝氨酸磷酸化的负调节，而受酪氨酸磷酸化的正调节。GSK-3失活被认为是促进神经元存活的一种机制。我们使用GSK-3亚型特异性小干扰RNA、显性负突变体或药理学抑制剂来研究两种GSK-3亚型在培养的皮层神经元中调节神经元存活的功能，以响应谷氨酸损伤或神经元成熟/衰老。令人惊讶的是，RNA干扰诱导的任一亚型的耗竭足以阻断谷氨酸诱导的兴奋性毒性，并且所产生的神经保护与两种GSK-3亚型中增强的N-末端丝氨酸磷酸化相关。然而，GSK-3 β耗竭比GSK-3 α耗竭在抑制延长培养中的自发性神经元死亡方面更有效。这种现象可能是由于在自发性神经元死亡过程中GSK-3 β Ser（9）去磷酸化导致的GSK-3 β活化的选择性和稳健抑制。GSK-3 α沉默导致GSK-3 β的酪氨酸磷酸化减少，表明酪氨酸磷酸化也是一个关键的自身调节事件。有趣的是，GSK-3抑制剂导致GSK-3 α Ser（21）磷酸化水平快速和持久增加，随后GSK-3 β Ser（9）磷酸化延迟增加，GSK-3 α Tyr（279）和GSK-3 β Tyr（216）磷酸化减少，因此暗示GSK-3自身调节水平增加。综上所述，我们的研究结果强调了GSK-3 α和GSK-3 β在细胞存活作用中的重要相似性和差异性，以及它们不同的调节模式。GSK-3亚型特异性抑制剂的开发似乎是治疗GSK-3介导的病理学的必要条件。
Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase consisting of two isoforms, alpha and beta. The activities of GSK-3 are regulated negatively by serine phosphorylation but positively by tyrosine phosphorylation. GSK-3 inactivation has been proposed as a mechanism to promote neuronal survival. We used GSK-3 isoform-specific small interfering RNAs, dominant-negative mutants, or pharmacological inhibitors to search for functions of the two GSK-3 isoforms in regulating neuronal survival in cultured cortical neurons in response to glutamate insult or during neuronal maturation/aging. Surprisingly, RNA interference-induced depletion of either isoform was sufficient to block glutamate-induced excitotoxicity, and the resulting neuroprotection was associated with enhanced N-terminal serine phosphorylation in both GSK-3 isoforms. However, GSK-3 beta depletion was more effective than GSK-3 alpha depletion in suppressing spontaneous neuronal death in extended culture. This phenomenon is likely due to selective and robust inhibition of GSK-3 beta activation resulting from GSK-3 beta Ser(9) dephosphorylation during the course of spontaneous neuronal death. GSK-3 alpha silencing resulted in reduced tyrosine phosphorylation of GSK-3 beta, suggesting that tyrosine phosphorylation is also a critical autoregulatory event. Interestingly, GSK-3 inhibitors caused a rapid and long-lasting increase in GSK-3 alpha Ser(21) phosphorylation levels, followed by a delayed increase in GSK-3 beta Ser(9) phosphorylation and a decrease in GSK-3 alpha Tyr(279) and GSK-3 beta Tyr(216) phosphorylation, thus implying additional levels of GSK-3 autoregulation. Taken together, our results underscore important similarities and dissimilarities of GSK-3 alpha and GSK-3 beta in the roles of cell survival as well as their distinct modes of regulation. The development of GSK-3 isoform-specific inhibitors seems to be warranted for treating GSK-3-mediated pathology.