Institute of Cell Biophysics, Russian Academy of Sciences, Russia.
Institute of Biology and Biomedicine, Lobachevsky State University of Nizhniy Novgorod, Russia.
Arch Biochem Biophys. 2018 Sep 15;654:126-135. doi: 10.1016/j.abb.2018.07.019. Epub 2018 Jul 27.
The Sip1 mutation plays the main role in pathogenesis of the Mowat-Wilson syndrome, which is characterized by the pronounced epileptic symptoms. Cortical neurons of homozygous mice with Sip1 mutation are resistant to AMPA receptor activators. Disturbances of the excitatory signaling components are also observed on such a phenomenon of neuroplasticity as hypoxic preconditioning. In this work, the mechanisms of loss of the AMPA receptor's ability to precondition by episodes of short-term hypoxia were investigated on cortical neurons derived from the Sip1 homozygous mice. The preconditioning effect was estimated by the level of suppression of the AMPA receptors activity with hypoxia episodes. Using fluorescence microscopy, we have shown that cortical neurons from the Sip1 mice are characterized by the absence of hypoxic preconditioning effect, whereas the amplitude of Ca-responses to the application of the AMPA receptor agonist, 5-Fluorowillardiine, in neurons from the Sip1 mice brainstem is suppressed by brief episodes of hypoxia. The mechanism responsible for this process is hypoxia-induced desensitization of the AMPA receptors, which is absent in the cortex neurons possessing the Sip1 mutation. However, the appearance of preconditioning in these neurons can be induced by phosphoinositide-3-kinase activation with a selective activator or an anti-inflammatory cytokine interleukin-10.
Sip1 突变在 Mowat-Wilson 综合征的发病机制中起主要作用,其特征是明显的癫痫症状。Sip1 突变纯合子小鼠的皮质神经元对 AMPA 受体激活剂具有抗性。在缺氧预处理等神经可塑性现象中,兴奋性信号传导成分也存在紊乱。在这项工作中,我们研究了源自 Sip1 纯合子小鼠的皮质神经元中,短时间缺氧引起 AMPA 受体失敏的机制。通过缺氧发作抑制 AMPA 受体活性的水平来评估预处理效应。使用荧光显微镜,我们已经表明,Sip1 小鼠的皮质神经元的特点是缺乏缺氧预处理效应,而在 Sip1 小鼠脑干神经元中应用 AMPA 受体激动剂 5-氟维林时,Ca-反应的幅度被短暂的缺氧发作所抑制。负责这一过程的机制是缺氧诱导的 AMPA 受体脱敏,而在携带 Sip1 突变的皮质神经元中则不存在。然而,通过使用选择性激活剂或抗炎细胞因子白细胞介素-10 激活磷酸肌醇-3-激酶,可以诱导这些神经元中出现预处理现象。