Akt is one of the most important downstream effectors of phosphatidylinositol 3-kinase/mTOR pathway. Hyperactivation and expression of this pathway are seen in a variety of neurological disorders including human temporal lobe epilepsy with hippocampal sclerosis (TLE-HS). Nevertheless, the expression and activation profiles of the Akt isoforms, Akt1, Akt2, and Akt3 and their functional roles in human TLE-HS have not been studied. We examined the protein expression and activation (phosphorylation) patterns of Akt and its isoforms in human hippocampal tissue from TLE and non-TLE patients. A phosphoproteomic approach followed by interactome analysis of each Akt isoform was used to understand protein-protein interactions and their role in TLE-HS pathology. Our results demonstrated activation of the Akt/mTOR pathway as well as activation of Akt downstream substrates like GSK3β, mTOR, and S6 in TLE-HS samples. Akt1 isoform levels were significantly increased in the TLE-HS samples as compared to the non-TLE samples. Most importantly, different isoforms were activated in different TLE-HS samples, Akt2 was activated in three samples, Akt2 and Akt1 were simultaneously activated in one sample and Akt3 was activated in two samples. Our phosphoproteomic screen across six TLE-HS samples identified 183 proteins phosphorylated by Akt isoforms, 29 of these proteins belong to cytoskeletal modification. Also, we were able to identify proteins of several other classes involved in glycolysis, neuronal development, protein folding and excitatory amino acid transport functions as Akt substrates. Taken together, our data offer clues to understand the role of Akt and its isoforms in underlying the pathology of TLE-HS and further, modulation of Akt/mTOR pathway using Akt isoforms specific inhibitors may offer a new therapeutic window for treatment of human TLE-HS.

中文翻译：

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磷酸化蛋白质组学分析揭示了人类颞叶癫痫伴海马硬化中细胞骨架蛋白的Akt亚型特异性调控。

Akt是磷脂酰肌醇3-激酶/ mTOR途径的最重要的下游效应子之一。在包括人颞叶癫痫伴海马硬化（TLE-HS）在内的多种神经系统疾病中都可以看到该通路的过度激活和表达。但是，尚未研究Akt亚型，Akt1，Akt2和Akt3的表达和激活特性及其在人TLE-HS中的功能。我们检查了来自TLE和非TLE患者的海马组织中Akt及其同工型的蛋白表达和激活（磷酸化）模式。使用磷酸化蛋白质组学方法，然后对每个Akt亚型进行相互作用组分析，以了解蛋白质-蛋白质相互作用及其在TLE-HS病理学中的作用。我们的结果证明了TLE-HS样品中Akt / mTOR途径的激活以及Akt下游底物（如GSK3β，mTOR和S6）的激活。与非TLE样品相比，TLE-HS样品中的Akt1亚型水平显着增加。最重要的是，在不同的TLE-HS样品中激活了不同的同工型，在三个样品中激活了Akt2，在一个样品中同时激活了Akt2和Akt1，在两个样品中激活了Akt3。我们对6个TLE-HS样品的磷酸化蛋白质组学筛查确定了183种被Akt亚型磷酸化的蛋白，其中29种属于细胞骨架修饰。同样，我们能够鉴定出与糖酵解，神经元发育，蛋白质折叠和兴奋性氨基酸转运功能有关的其他几类蛋白质作为Akt底物。在一起