Department of Anatomy and Neurobiology, University of Vermont, Colchester, VT, USA.
Stroke. 2011 Nov;42(11):3231-7. doi: 10.1161/STROKEAHA.111.623280. Epub 2011 Aug 11.
The formation of reactive astrocytes is common after central nervous system injuries such as stroke. However, the signaling pathway(s) that control astrocyte formation and functions are poorly defined. We assess the effects of Notch 1 signaling in peri-infarct-reactive astrocytes after stroke.
We examined reactive astrocyte formation in the peri-infarct area 3 days after distal middle cerebral artery occlusion with or without γ-secretase inhibitor treatment. To directly study the effects of inhibiting a γ-secretase cleavage target in reactive astrocytes, we generated glial fibrillary acidic protein-CreER™:Notch 1 conditional knockout mice.
Gamma-secretase inhibitor treatment after stroke decreased the number of proliferative glial fibrillary acidic protein-positive reactive astrocytes and RC2-positive reactive astrocytes directly adjacent to the infarct core. The decrease in reactive astrocytes correlated with an increased number of CD45-positive cells that invaded into the peri-infarct area. To study the influence of reactive astrocytes on immune cell invasion, ex vivo immune cell invasion assays were performed. We found that a γ-secretase-mediated pathway in astrocytes affected Jurkat cell invasion. After tamoxifen treatment, glial fibrillary acidic protein-CreER™:Notch 1 conditional knockout mice had a significantly decreased number of proliferating reactive astrocytes and RC2-positive reactive astrocytes. Tamoxifen treatment also led to an increased number of CD45-positive cells that invaded the peri-infarct area.
Our results demonstrate that proliferating and RC2-positive reactive astrocytes are regulated by Notch 1 signal transduction and control immune cell invasion after stroke.
脑卒中 等中枢神经系统损伤后，反应性星形胶质细胞的形成较为常见。然而，控制星形胶质细胞形成和功能的信号通路尚不清楚。我们评估了 Notch1 信号在脑卒中后梗死周围反应性星形胶质细胞中的作用。
我们通过或不通过γ-分泌酶抑制剂处理，在大脑中动脉远端闭塞 3 天后检查梗死周围区域反应性星形胶质细胞的形成。为了直接研究抑制反应性星形胶质细胞中γ-分泌酶切割靶点的作用，我们生成了胶质纤维酸性蛋白-CreER™： Notch1 条件性敲除小鼠。
脑卒中后给予γ-分泌酶抑制剂处理，减少了增殖性胶质纤维酸性蛋白阳性反应性星形胶质细胞和紧邻梗死核心的 RC2 阳性反应性星形胶质细胞的数量。反应性星形胶质细胞数量的减少与浸润到梗死周围区域的 CD45 阳性细胞数量的增加相关。为了研究反应性星形胶质细胞对免疫细胞浸润的影响，我们进行了体外免疫细胞浸润实验。我们发现星形胶质细胞中的 γ-分泌酶介导途径影响 Jurkat 细胞的浸润。给予他莫昔芬处理后，胶质纤维酸性蛋白-CreER™： Notch1 条件性敲除小鼠的增殖性反应性星形胶质细胞和 RC2 阳性反应性星形胶质细胞数量明显减少。他莫昔芬处理还导致浸润到梗死周围区域的 CD45 阳性细胞数量增加。
我们的结果表明，增殖性和 RC2 阳性反应性星形胶质细胞受 Notch1 信号转导调节，并控制脑卒中后免疫细胞的浸润。
