Tucker Budd A, Rahimtula Masuma, Mearow Karen M
Division of Basic Medical Sciences, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3V6, Canada.
J Comp Neurol. 2005 Jun 6;486(3):267-80. doi: 10.1002/cne.20518.
Neurite growth is influenced by many factors, including the availability of trophic support as well as the extracellular environment. In this study, we have investigated whether attachment to a permissive culture substrate such as laminin is sufficient to promote neurite outgrowth from dorsal root ganglion neurons in the absence of added nerve growth factor (NGF) and whether this attachment can enhance the response of these neurons to NGF. Adult dorsal root ganglia neurons plated on surfaces coated with a thin film of laminin exhibited increased neurite outgrowth. This effect was integrin-dependent as it was attenuated by treatment with RGD (arginine-glycine-aspartate) peptides and by a beta1-integrin blocking antibody. The addition of NGF resulted in a significant increase in the integrin-dependent outgrowth. We have correlated this increase in growth with increased expression of integrin subunits and activation of known downstream signaling intermediates such as focal adhesion kinase, Src, and Akt. We have also examined pathway cooperation through the use of an Src-specific inhibitor, PP2, and a beta1-integrin blocking antibody, beta1i, by observing downstream signaling intermediates in both integrin and growth factor signaling pathways. These results are among the first to detail the importance of interactions between neurotrophin- and integrin-activated signaling in adult primary neurons.
神经突生长受多种因素影响，包括营养支持的可获得性以及细胞外环境。在本研究中，我们调查了在不添加神经生长因子（NGF）的情况下，附着于诸如层粘连蛋白等允许性培养底物是否足以促进背根神经节神经元的神经突生长，以及这种附着是否能增强这些神经元对NGF的反应。接种在涂有薄层粘连蛋白的表面上的成年背根神经节神经元表现出神经突生长增加。这种效应依赖于整合素，因为用RGD（精氨酸 - 甘氨酸 - 天冬氨酸）肽处理以及用β1整合素阻断抗体处理会使其减弱。添加NGF导致整合素依赖性生长显著增加。我们已将这种生长增加与整合素亚基表达增加以及已知下游信号中间体（如粘着斑激酶、Src和Akt）的激活相关联。我们还通过使用Src特异性抑制剂PP2和β1整合素阻断抗体β1i，观察整合素和生长因子信号通路中的下游信号中间体，研究了信号通路的协同作用。这些结果首次详细阐述了神经营养因子和整合素激活信号在成年原代神经元中相互作用的重要性。
