Department of Orthopaedics, Dongzhimen Hospital, Beijing University of Chinese Medicine, Beijing 100853, P.R. China.
Department of Orthopaedics, Chinese PLA General Hospital, Beijing 100853, P.R. China.
Int J Mol Med. 2018 May;41(5):2832-2838. doi: 10.3892/ijmm.2018.3459. Epub 2018 Feb 6.
The aim of the present study was to elucidate the expression and role of the phosphatidylinositol 3‑kinase (PI3K)/Akt/forkhead box O3 (FOXO3a) pathway in the regeneration of the spinal cord following spinal cord injury (SCI), and its regulatory effect on tumor necrosis factor (TNF)-α and cyclin-dependent kinase inhibitor 1B (p27kip1) expression. Firstly, in a Sprague-Dawley rat model of SCI, western blot analysis revealed that the protein levels of PI3K, phosphorylated Akt and FOXO3a were markedly inhibited compared with those in the sham control group. In vitro experiments were also conducted, in which primary dissociated cultures of rat dorsal spinal cord cells were induced with lipopolysaccharide (LPS; 4 µg/ml). The downregulation of PI3K using LY294002 markedly suppressed cell viability, reduced the protein levels of FOXO3a and p27kip1, and increased TNF-α protein production in the LPS-induced spinal cord cells. In addition, when the LPS-induced spinal cord cells were infected with FOXO3a adenoviral vectors, the overexpression of FOXO3 markedly promoted cell proliferation, activated p27kip1 protein levels and inhibited TNF-α protein production in the spinal cord cells. These results suggest that the PI3K/Akt/FOXO3a pathway regulates regeneration following SCI in adult rats via its modulatory effects on TNF-α and p27kip1 expression.
本研究旨在阐明磷脂酰肌醇 3-激酶（PI3K）/蛋白激酶 B（Akt）/叉头框蛋白 O3（FOXO3a）通路在脊髓损伤（SCI）后脊髓再生中的表达和作用，及其对肿瘤坏死因子（TNF）-α和细胞周期蛋白依赖性激酶抑制剂 1B（p27kip1）表达的调节作用。首先，在 SCI 的 Sprague-Dawley 大鼠模型中，Western blot 分析显示，与假手术对照组相比，PI3K、磷酸化 Akt 和 FOXO3a 的蛋白水平明显受到抑制。还进行了体外实验，其中用脂多糖（LPS；4μg/ml）诱导大鼠背根脊髓细胞的原代分离培养物。使用 LY294002 下调 PI3K 可显著抑制细胞活力，降低 LPS 诱导的脊髓细胞中 FOXO3a 和 p27kip1 的蛋白水平，并增加 TNF-α 蛋白的产生。此外，当 LPS 诱导的脊髓细胞感染 FOXO3a 腺病毒载体时，FOXO3a 的过表达可显著促进细胞增殖，激活 p27kip1 蛋白水平，并抑制脊髓细胞中 TNF-α 蛋白的产生。这些结果表明，PI3K/Akt/FOXO3a 通路通过调节 TNF-α 和 p27kip1 的表达来调节成年大鼠 SCI 后的再生。
