Department of Neurology, Tokai University School of Medicine, 143 Shimo-Kasuya, Isehara, Kanagawa, 259-1193, Japan.
Support Center for Medical Research and Education, Tokai University, Isehara, Japan.
Mol Biol Rep. 2020 Sep;47(9):6479-6485. doi: 10.1007/s11033-020-05688-w. Epub 2020 Sep 14.
We have previously reported that inositol hexakisphosphate kinase (InsPK)2 mediates cell death. InsPK2 is abundantly expressed in anterior horn cells of the mammalian spinal cord. We investigated the role of InsPK2 in spinal cords of patients with amyotrophic lateral sclerosis (ALS). Autopsy specimens of lumbar spinal cords from ten patients with sporadic ALS and five non-neurological disease patients (NNDPs) were obtained. We performed quantitative real-time PCR, immunostaining, and western blotting for InsPK1, InsPK2, InsPK3, protein kinase B (Akt), casein kinase 2 (CK2), and 90-kDa heat-shock protein (HSP90). In contrast to InsPK1 and InsPK3 mRNA expression, InsPK2 levels in anterior horn cells of the spinal cord were significantly increased in ALS patients compared to NNDPs. In ALS patients, InsPK2 translocated from the nucleus to the cytoplasm. However, we observed a decrease in HSP90, CK2, and Akt activity in ALS patients compared to NNDPs. A previous study reported that InsPK2 activity is suppressed after binding to HSP90 and subsequent phosphorylation and degradation by CK2, thus decreasing InsPK2 activity. However, InsP, which is generated by InsPK2, can compete with Akt for PH domain binding. Consequently, InsP can inhibit Akt phosphorylation. Our results suggest that InsPK2 is activated in the spinal cord of patients with ALS and may play an important role in ALS by inducing cell death mechanisms via Akt, CK2, and HSP90 pathways.
我们之前曾报道过肌醇六磷酸激酶（InsPK）2 可介导细胞死亡。InsPK2 在哺乳动物脊髓前角细胞中大量表达。我们研究了 InsPK2 在肌萎缩侧索硬化症（ALS）患者脊髓中的作用。从 10 例散发性 ALS 患者和 5 例非神经疾病患者（NNDPs）的腰段脊髓获得尸检标本。我们进行了定量实时 PCR、免疫染色和 Western blot 分析，检测 InsPK1、InsPK2、InsPK3、蛋白激酶 B（Akt）、酪蛋白激酶 2（CK2）和 90kDa 热休克蛋白（HSP90）。与 InsPK1 和 InsPK3 mRNA 表达相反，与 NNDPs 相比，ALS 患者脊髓前角细胞中的 InsPK2 水平显著增加。在 ALS 患者中，InsPK2 从细胞核转位到细胞质。然而，与 NNDPs 相比，我们观察到 ALS 患者的 HSP90、CK2 和 Akt 活性下降。先前的一项研究报道，InsPK2 活性在与 HSP90 结合并随后被 CK2 磷酸化和降解后受到抑制，从而降低了 InsPK2 活性。然而，InsPK2 产生的 InsP 可以与 Akt 竞争 PH 结构域结合。因此，InsP 可以抑制 Akt 磷酸化。我们的结果表明，InsPK2 在 ALS 患者的脊髓中被激活，并且可能通过 Akt、CK2 和 HSP90 途径诱导细胞死亡机制在 ALS 中发挥重要作用。
