Fibrinogen-cellular prion protein complex formation on astrocytes
Fibrinogen-cellular prion protein complex formation on astrocytes
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DOI：
10.1152/jn.00224.2020
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发表时间：
2020-08-01
影响因子：
2.5
通讯作者：
Lominadze, David
中科院分区：
文献类型：
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作者：
Charkviani, Mariam;Muradashvili, Nino;Lominadze, David
创伤性脑损伤（Traumatic brain injury，TBI）是最常见的神经系统疾病之一，可导致记忆力下降，尤其是短时记忆（short-term memory，STM）。我们发现，在TBI诱导的炎症反应中，血中纤维蛋白原（Fg）含量的增加增强了血管蛋白的胞吞作用和血管-星形胶质细胞界面中外渗的Fg的沉积。此外，我们发现，沉积的细胞朊蛋白（PrPC）也增加了血管星形胶质细胞终足接口。然而，未证实Fg和PrPC的关联。现在。我们的目的是确定Fg是否可以与星形胶质细胞上的PrP（C）结合并引起其活化。用单独的培养基（对照）、Fg（2 mg/mL或4 mg/mL）处理培养的小鼠脑星形胶质细胞。4 mg/mL的Fg，存在功能阻断性抗PrPC肽或抗小鼠IgG、功能阻断性抗PrPC肽或单独的抗小鼠IgG。处理后，收集细胞裂解物并通过Western印迹或免疫共沉淀进行分析，或固定星形胶质细胞并用免疫组织化学评估其活化。结果显示，Fg剂量依赖性地激活星形胶质细胞，增加PrPC和酪氨酸（原肌球蛋白）受体激酶B（Trk B）及PrP基因的表达。阻断PrP（C）的功能可降低这些作用。免疫共沉淀证实Fg和PrPC的关联。由于已知朊病毒蛋白比淀粉样蛋白β对记忆力降低的影响更大，并且TrkB的激活参与神经变性，我们的研究结果证实了星形胶质细胞上可能形成Fg-PrPC和Fg诱导的TrkB过表达，这提示了先前在轻中度TBI期间观察到的STM减少的可能触发机制。可与培养的小鼠脑星形胶质细胞表面的细胞朊蛋白（PrPC）结合。在高水平下，Fg导致星形胶质细胞PrPC上调和星形胶质细胞活化，并伴有酪氨酸受体激酶B（Trk B）过表达。这导致一氧化氮（NO）的产生和活性氧物质（ROS）的产生。Fg/PrPC相互作用可能是TrkB-NO-ROS轴激活和由此产生的星形胶质细胞介导的神经变性的触发机制。
Traumatic brain injury (TBI) is one of the most common neurological disorders causing memory reduction, particularly short-term memory (STM). We showed that, during TBI-induced inflammation, increased blood content of fibrinogen (Fg) enhanced vascular protein transcytosis and deposition of extravasated Fg in vasculo-astrocyte interfaces. In addition, we found that deposition of cellular prion protein (PrPC) was also increased in the vasculoastrocyte endfeet interface. However, association of Fg and PrPC was not confirmed. Presently. we aimed to define whether Fg can associate with PrP(C )on astrocytes and cause their activation. Cultured mouse brain astrocytes were treated with medium alone (control), Fg (2 mg/mL or 4 mg/mL). 4 mg/mL of Fg in the presence of a function-blocking anti-PrPC peptide or anti-mouse IgG, function-blocking anti-PrPC peptide, or anti-mouse IgG alone. After treatment, either cell lysates were collected and analyzed via Western blot or coimmunoprecipitation was performed, or astrocytes were fixed and their activation was assessed with immunohistochemistry. Results showed that Fg dose-dependently activated astrocytes, increased expressions of PrPC and tyrosine (tropomyosin) receptor kinase B (TrkB), and PrP gene. Blocking the function of PrP(C )reduced these effects. Coimmunoprecipitation demonstrated Fg and PrPC association. Since it is known that prion protein has a greater effect on memory reduction than amyloid beta, and that activation of TrkB is involved in neurodegeneration, our findings confirming the possible formation of Fg-PrPC and Fg-induced overexpression of TrkB on astrocytes suggest a possible triggering mechanism for STM reduction that was seen previously during mild-to-moderate TBI.NEW & NOTEWORTHY For the first time we showed that fibrinogen (Fg) can associate with cellular prion protein (PrPC) on the surface of cultured mouse brain astrocytes. At high levels, Fg causes upregulation of astrocyte PrPC and astrocyte activation accompanied with overexpression of tyrosine receptor kinase B (TrkB). which results in nitric oxide (NO) production and generation of reactive oxygen species (ROS). Fg/PrPC interaction can be a triggering mechanism for TrkB-NO-ROS axis activation and the resultant astrocyte-mediated neurodegeneration.