Centro Multidisciplinario de Estudios en Biotecnología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mexico.
Global Health de México S. A. de C. V., Guadalajara, Mexico.
Front Immunol. 2018 Jan 29;9:92. doi: 10.3389/fimmu.2018.00092. eCollection 2018.
Glycogen synthase kinase 3 (GSK3) is a constitutive enzyme implicated in the regulation of cytokine expression and the inflammatory response during bacterial infections. Mammals have two GSK3 isoforms named GSK3α and GSK3β that plays different but often overlapping functions. Although the role of GSK3β in cytokine regulation during the inflammatory response caused by bacteria is well described, GSK3α has not been found to participate in this process. Therefore, we tested if GSK3α may act as a regulatory isoform in the cytokine expression by bovine endothelial cells infected with because this bacterium is one of the major pathogens that cause tissue damage associated with inflammatory dysfunction. Interestingly, although both isoforms were phosphorylated-inactivated, we consistently observed a higher phosphorylation of GSK3α at Ser21 than that of GSK3β at Ser9 after bacterial challenge. During a temporal course of infection, we characterized a molecular switch from pro-inflammatory cytokine expression (IL-8), promoted by nuclear factor-kappa B (NF-κB), at an early stage (2 h) to an anti-inflammatory cytokine expression (IL-10), promoted by cAMP response element binding (CREB), at a later stage (6 h). We observed an indirect effect of GSK3α activity on NF-κB activation that resulted in a low phosphorylation of CREB at Ser133, a decreased interaction between CREB and the co-activator CREB-binding protein (CBP), and a lower expression level of IL-10. Gene silencing of GSK3α and GSK3β with siRNA indicated that GSK3α knockout promoted the interaction between CREB and CBP that, in turn, increased the expression of IL-10, reduced the interaction of NF-κB with CBP, and reduced the expression of IL-8. These results indicate that GSK3α functions as the primary isoform that regulates the expression of IL-10 in endothelial cells infected with .
糖原合酶激酶 3（GSK3）是一种组成性酶，参与细菌感染时细胞因子表达和炎症反应的调节。哺乳动物有两种 GSK3 同工型，分别命名为 GSK3α 和 GSK3β，它们发挥着不同但经常重叠的功能。尽管 GSK3β 在细菌引起的炎症反应中细胞因子调节的作用已得到很好的描述，但尚未发现 GSK3α 参与该过程。因此，我们测试了 GSK3α 是否可以作为感染的牛内皮细胞中细胞因子表达的调节同工型，因为这种细菌是引起与炎症功能障碍相关的组织损伤的主要病原体之一。有趣的是，尽管两种同工型都被磷酸化失活，但我们始终观察到细菌刺激后 GSK3α 在 Ser21 的磷酸化程度高于 GSK3β 在 Ser9 的磷酸化程度。在感染的时间过程中，我们从早期（2 小时）由核因子-κB（NF-κB）促进的促炎细胞因子表达（IL-8）到后期（6 小时）由环磷酸腺苷反应元件结合（CREB）促进的抗炎细胞因子表达（IL-10），鉴定出一种分子开关。我们观察到 GSK3α 活性对 NF-κB 激活的间接影响，导致 CREB 在 Ser133 的磷酸化程度降低，CREB 与共激活因子 CREB 结合蛋白（CBP）的相互作用减少，以及 IL-10 的表达水平降低。用 siRNA 沉默 GSK3α 和 GSK3β 基因表明，GSK3α 敲除促进了 CREB 与 CBP 的相互作用，进而增加了 IL-10 的表达，减少了 NF-κB 与 CBP 的相互作用，降低了 IL-8 的表达。这些结果表明，GSK3α 作为调节感染的内皮细胞中 IL-10 表达的主要同工型发挥作用。
