A2: PROJ 2: NEUROGENESIS IN THE ADULT BRAIN: ROLE OF BASAL LAMINA NETWORK

A2：项目 2：成人大脑中的神经发生：基底层网络的作用

• 批准号: 7336064
• 负责人: FREDERIC MERCIER
• 金额: $ 6.47万
• 依托单位: UNIVERSITY OF HAWAII AT MANOA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-17 至 2007-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7336064
• 关键词: basal lamina; brain; growth factor; heparan sulfate; heparin; proteoglycan; role; stem cells

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The major goal of this project is to identify the mechanisms leading to neural stem cell proliferation and differentiation in the neurogenic niche of adult brain. We recently characterized by confocal and transmission electron microscopy specialized basal lamina labyrinths (fractones) that directly contact neural progenitor cells and neural stem cells in the neurogenic niche (Mercier et al., 2002; 2003). Our hypothesis is that fractones are sites of extracellular matrix/growth factor interactions that ultimately trigger proliferation and differentiation of abutting neural stem cells. Last year we reported that fractones contain ubiquitous extracellular matrix components of basal laminae such as collagen IV, laminin gamma-1 and beta-1, nidogen, and the heparan sulfate proteoglycan (HSPG) perlecan. Perlecan is a high affinity binder and activator of the heparin-binding growth factor fibroblast growth factor-2 (FGF-2). Our working hypothesis for this year was that fractones capture heparin-binding growth factors to trigger neurogenesis. We studied the binding activity of FGF-2, amphiregulin (AR), and heparin-binding epidermal growth factor (HB-EGF), three powerful neurogenic factors. After biotinylation, each growth factor was either incubated on frozen sections of the adult rat brain (in situ binding), or introduced in vivo by intracerebroventricular injection (in vivo binding). Using both methods, we demonstrated that FGF-2 and AR strongly and exclusively bind to fractones. In contrast, the diffuse binding sites of HB-EGF in the ventricle walls indicated that HB-EGF regulates stem cell fate by means that do not involve fractone binding. The binding of FGF-2 and AR to fractones is highly important for the neural stem cell field, revealing for the first time a mechanism by which growth factors trigger stem cell activation in the neurogenic niche. Future research will focus on identifying fractone HSPG and other molecules that bind to FGF-2, and the precise mechanisms by which these molecules interact to trigger neural stem cell activation. Understanding the mechanisms occurring in the neural stem cell niche will permit to accurately design stem cell therapies for neurotrauma and neurodegenerative diseases.

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。本项目的主要目标是确定成人大脑神经源性生态位中导致神经干细胞增殖和分化的机制。我们最近用共聚焦和透射电子显微镜对直接接触神经祖细胞和神经干细胞的特殊基底板迷路（分形迷路）进行了表征（Mercier等，2002;2003）。我们的假设是，分裂体是细胞外基质/生长因子相互作用的位点，最终触发相邻神经干细胞的增殖和分化。去年我们报道了fracactones含有普遍存在的基底层细胞外基质成分，如胶原IV，层粘连蛋白γ -1和β -1，氮素和硫酸肝素蛋白多糖（HSPG） perlecan。Perlecan是肝素结合生长因子成纤维细胞生长因子-2 （FGF-2）的高亲和力结合剂和激活剂。我们今年的工作假设是，分形酮捕获肝素结合生长因子来触发神经发生。我们研究了FGF-2、双调节蛋白（AR）和肝素结合表皮生长因子（HB-EGF）这三种强大的神经源性因子的结合活性。生物素化后，每种生长因子要么在成年大鼠脑的冷冻切片上孵育（原位结合），要么通过脑室内注射引入体内（体内结合）。使用这两种方法，我们证明了FGF-2和AR强烈且排他地与分形蛋白结合。相反，HB-EGF在脑室壁的弥漫性结合位点表明，HB-EGF通过不涉及fracone结合的方式调节干细胞的命运。FGF-2和AR与fracactones的结合在神经干细胞领域非常重要，首次揭示了生长因子在神经源性生态位中触发干细胞激活的机制。未来的研究将集中于识别fractone HSPG和其他与FGF-2结合的分子，以及这些分子相互作用触发神经干细胞激活的确切机制。了解发生在神经干细胞生态位中的机制将允许准确地设计用于神经创伤和神经退行性疾病的干细胞疗法。