Stroke is the leading cause of long-term motor disability and cognitive impairment. Recently, neurogenesis has become an attractive strategy for the chronic recovery of stroke. It is important to understand the molecular mechanism that promotes neural stem cell (NSC) neurogenesis for future NSC-based therapies. Our previous study showed that Momordica charantia polysaccharides (MCPs) exerted neuroprotective effects on stroke via their anti-oxidant and anti-inflammation activities. However, it remains unknown whether MCPs promote NSC neurogenesis after cerebral ischemic/reperfusion injury (IRI). We investigated MCPs’ function in differentiation of neural stem cells (NSCs) in vivo and in vitro experiments. Based on a middle cerebral artery occlusion (MCAO) rat model, the effect of MCPs on neuronal differentiation after MCAO was analyzed. Primary NSCs and neural stem cell line C17.2 were cultured and subjected to glutamate stimulation to establish the cell model of IRI. We evaluated the effect of MCPs on NSC differentiation in IRI cell model by Western blot and immunofluorescence staining. The SIRT1 activity of NSCs post glutamate stimulation was also evaluated by CELL SIRT1 COLORIMETRY ASSAY KIT. In addition, molecular mechanism was clarified by employing the activator and inhibitor of SIRT1. MCPs had no effects on the differentiation of neural stem cells under physiological conditions while shifted NSC differentiation potential from the gliogenic to neurogenic lineage under pathological conditions. Activation of SIRT1 with MCPs was responsible for the neuronal differentiation of C17.2-NSCs. The neuronal differentiation effect of MCPs was attributed to upregulation SIRT1-mediated deacetylation of β-catenin. MCP-induced deacetylation via SIRT1 promoted nuclear accumulation of β-catenin in NSCs. Our findings indicate that the deacetylation of β-catenin by SIRT1 represents a critical mechanism of action of MCPs in promoting NSC neuronal differentiation. It provides an improved understanding of molecular mechanism underlying neuroprotective effects of MCPs in IRI, indicating its potential role on treating ischemic stroke especially chronic recovery.

中文翻译：

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苦瓜多糖通过SIRT1/β-catenin轴调节脑缺血/再灌注神经干细胞的分化


中风是长期运动障碍和认知障碍的主要原因。最近，神经发生已成为中风慢性恢复的一种有吸引力的策略。了解促进神经干细胞 (NSC) 神经发生的分子机制对于未来基于 NSC 的治疗非常重要。我们之前的研究表明，苦瓜多糖（MCP）通过其抗氧化和抗炎活性对中风发挥神经保护作用。然而，MCPs是否促进脑缺血/再灌注损伤（IRI）后NSC神经发生仍不清楚。我们在体内和体外实验中研究了 MCP 在神经干细胞 (NSC) 分化中的功能。基于大脑中动脉闭塞（MCAO）大鼠模型，分析MCPs对MCAO后神经元分化的影响。培养原代NSCs和神经干细胞系C17.2，并进行谷氨酸刺激，建立IRI细胞模型。我们通过蛋白质印迹和免疫荧光染色评估了 MCP 对 IRI 细胞模型中 NSC 分化的影响。还通过 CELL SIRT1 比色测定试剂盒评估了谷氨酸刺激后 NSC 的 SIRT1 活性。此外，通过使用SIRT1的激活剂和抑制剂阐明了分子机制。 MCP 在生理条件下对神经干细胞的分化没有影响，而在病理条件下将 NSC 分化潜力从胶质细胞谱系转移到神经源细胞谱系。 MCP 激活 SIRT1 导致 C17.2-NSC 的神经元分化。 MCP 的神经元分化作用归因于 SIRT1 介导的 β-连环蛋白脱乙酰化的上调。 MCP 通过 SIRT1 诱导的去乙酰化促进 NSC 中 β-catenin 的核积累。我们的研究结果表明，SIRT1 对 β-catenin 的去乙酰化代表了 MCP 促进 NSC 神经元分化的关键作用机制。它提供了对 MCP 在 IRI 中神经保护作用的分子机制的更好理解，表明其在治疗缺血性中风尤其是慢性恢复中的潜在作用。