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Title: Neurotrophin 3及其高亲和力受体TrkC在神经干细胞分化过程中的功能及机制研究
Author: 胡昕华
Degree Level: 博士
Issued Date: 2004
Degree Grantor: 中国科学院神经科学研究所
Place of Degree Grantor: 中国科学院神经科学研究所
Supervisor: 冯林音
Keyword: 神经干细胞 ; 分化 ; 核转位
Abstract: Neurotrophin3通过Erkl/2而非PI3K通路引导新生大鼠海马区神经干细胞向少突胶质细胞方向分化在小鼠胚胎大脑皮层干细胞的发育过程中,neurotrophin3(NT3)引导干细胞从对称性分裂转向不对称分裂,提示NT3可能是神经干细胞发育分化的一个早期信号。本文应用体外培养的新生大鼠海马区神经球作为神经干细胞的分化模型,研究发现:神经干细胞体外分化24小时,NT3在不影响少突胶质细胞前体细胞(oligodendorcyte precursors,OLPs)增殖和存活的情况下,通过extrocellular signal-related kinase1/2(Erlc1/2)信号通路促进神经干细胞向OLP方向分化。NT3的刺激可在神经干细胞内引起一系列反应,包括Erkl/2和Akt信号通路的激活,以及转录因子oligodendrocyte Iineage gene-l(Olig-l)的表达水平上调(已知该转录因子在少突胶质细胞的发育过程中起重要作用)。如果在NT3处理的同时用Erkl/2上游蛋白MEK 1/2的抑制剂UO126阻断Erkl/2的磷酸化,则NT3介导的Olig-1上调及OLP分化就会受到抑制。与之相对地,如果在NT3处理的同时用Akt上游蛋白PI3K的抑制剂LY294002阻断Akt的磷酸化,对NT3介导的Olig-1上调及OLP分化并无影响。这些实验结果提示:NT3通过Erkl/2而非PI3K通路上调转录因子Plig-1的表达来介导神经干细胞的OLP分化。NT3和bFGF在神经干细胞的分化过程中通过FGFRI和TrkC的交互作用引起TrkC的剪切入核应用体外培养的新生大鼠海马区神经球作为神经干细胞发育分化的研究系统,可见随着神经干细胞的不断分化成熟,出现Trkc的核转位(nuclear translocation)现象。神经干细胞分化24小时,Trkc定位于细胞膜表面;神经干细胞分化72小时,TrkC开始定位于细胞核。分别用抗TrkC胞外段和胞内段的抗体来检测 TrkC的表达,发现核转位的TrkC丢失了其全长片段的N端局部结构。NT3和bFGF共作用于神经干细胞可促进TrkC核转位。免疫共沉淀实验表明FGFR]和TrkC之间存在交互作用,可能对促进TrkC的剪切入核有所帮助。我们首次报道了TI.kC的核转位现象,并且初步设想NT3和bFGF在神经干细胞的分化过程中通过FGFRI和TI.kC的交互作用引起TrkC的剪切入核。
English Abstract: Erkl/2 but not PI3K Pathway Is Required for Neurotrophin 3-Induced Oligodendrocyte Differentiation of Postnatal Neural Stem Using cultured postnatal hippocampal stem cells (NSCs) as a model, we demonstrated that NT3-stimulation causes NSCs to differentiate into OLPs through an Erkl/2-dependent pathway without influencing the proliferation and survival of OLPs. NT3 induced phosphorylation of Erkl/2 or Akt and increase of expression of Olig-1, a transcriptional factor known to participate in oligodendrocyte development. Application of U0126, a specific inhibitor of MEK1/2 which are upstream to Erkl/2, suppressed the expression of Olig-1 and prevented NSC differentiation into OLPs in response to NT3 stimulation. However, administration of LY294002, an inhibitor of PI3K which are upstream to Akt, did not affect the effect of NT3 on the expression of Olig-1 and on NSC differentiation into OLPs. These results suggest that NT3 induce NSCs to differentiate into OLPs by enhancing the expression of Olig-1 through an Erkl/2-dependent pathway. Collaboration of NT3 and bFGF Increased Nuclear Translocation of TrkC whereas Enhanced Interaction between FGFR1 and TrkC during the Differentiation of Postnatal Neural Stem Cells Using cultured postnatal hippocampal NSCs as a model, we demonstrated that TrkC translocated into nucleus during the differentiation of neural stem cells. Immunocytochemical results showed that TrkC were located on the plasma membrane within 24 hours however, began to translocate into nucleus within 72 hours of the differentiation of NSCs. Using specific antibodies that recognize extracellular or intracellular domain of TrkC respectively, we found that TrkC translocated into nucleus in a short-length isoform which lose N-terminal structure. NT3 upregulated nuclear translocation of TrkC in the presence of bFGF. Co-immunoprecipitation result demonstrated that collaboration of bFGF and NT3 enhanced interaction between FGFR1 and TrkC, which might be involved in nuclear translocation of TrkC. In short, we reported nuclear translocation of TrkC for the first time, which might be dependent on the interaction between FGFR1 and TrkC during the differentiation of NSCs.
Language: 中文
Content Type: 学位论文
URI: http://ir.sibs.ac.cn/handle/331001/2259
Appears in Collections:神经所(总)_学位论文

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Recommended Citation:
Neurotrophin 3及其高亲和力受体TrkC在神经干细胞分化过程中的功能及机制研究.胡昕华[d].中国科学院神经科学研究所,2004.20-25
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