Data_Sheet_1_Stat1 is an inducible transcriptional repressor of neural stem cells self-renewal program during neuroinflammation.csv

A central issue in regenerative medicine is understanding the mechanisms that regulate the self-renewal of endogenous stem cells in response to injury and disease. Interferons increase hematopoietic stem cells during infection by activating STAT1, but the mechanisms by which STAT1 regulates intrinsic programs in neural stem cells (NSCs) during neuroinflammation is less known. Here we explored the role of STAT1 on NSC self-renewal. We show that overexpressing Stat1 in NSCs derived from the subventricular zone (SVZ) decreases NSC self-renewal capacity while Stat1 deletion increases NSC self-renewal, neurogenesis, and oligodendrogenesis in isolated NSCs. Importantly, we find upregulation of STAT1 in NSCs in a mouse model of multiple sclerosis (MS) and an increase in pathological T cells expressing IFN-γ rather than interleukin 17 (IL-17) in the cerebrospinal fluid of affected mice. We find IFN-γ is superior to IL-17 in reducing proliferation and precipitating an abnormal NSC phenotype featuring increased STAT1 phosphorylation and Stat1 and p16ink4a gene expression. Notably, Stat1–/– NSCs were resistant to the effect of IFN-γ. Lastly, we identified a Stat1-dependent gene expression profile associated with an increase in the Sox9 transcription factor, a regulator of self-renewal. Stat1 binds and transcriptionally represses Sox9 in a transcriptional luciferase assay. We conclude that Stat1 serves as an inducible checkpoint for NSC self-renewal that is upregulated during chronic brain inflammation leading to decreased self-renewal. As such, Stat1 may be a potential target to modulate for next generation therapies to prevent progression and loss of repair function in NSCs/neural progenitors in MS.

再生医学的核心议题之一，是阐明调控内源性干细胞响应损伤与疾病时自我更新的分子机制。干扰素可通过激活信号转导与转录激活因子1（STAT1）在感染期间扩增造血干细胞，但在神经炎症过程中，STAT1调控神经干细胞（neural stem cells, NSCs）内在程序的机制仍有待明确。
本研究探讨了STAT1对神经干细胞自我更新的调控作用。我们发现，在侧脑室下区（subventricular zone, SVZ）来源的神经干细胞中过表达Stat1会降低其自我更新能力，而敲除Stat1则可提升分离培养的神经干细胞的自我更新能力、神经发生与少突胶质细胞生成水平。
重要的是，我们在多发性硬化症（multiple sclerosis, MS）小鼠模型的神经干细胞中观察到STAT1表达上调，且患病小鼠脑脊液中表达干扰素-γ（IFN-γ）的病理性T细胞数量多于表达白细胞介素17（interleukin 17, IL-17）的T细胞。
我们证实，IFN-γ在抑制神经干细胞增殖、诱导以STAT1磷酸化水平升高、Stat1与p16ink4a基因表达上调为特征的异常神经干细胞表型方面，效果优于IL-17。值得注意的是，Stat1基因敲除的神经干细胞对IFN-γ的作用产生了抗性。
最后，我们鉴定出一条依赖于Stat1的基因表达谱，该谱与自我更新调控因子Sox9转录因子的表达上调相关；在转录荧光素酶报告实验中，Stat1可结合并转录抑制Sox9的表达。
综上，Stat1可作为神经干细胞自我更新的诱导性检查点，在慢性脑炎症过程中表达上调并导致自我更新能力下降。因此，Stat1或可作为下一代治疗策略的潜在靶点，用于调控多发性硬化症患者神经干细胞/神经前体细胞的修复功能，防止其功能衰退与丢失。