Mehlen Patrick, Mazelin Laetitia
Apoptosis/Differentiation Laboratory, Equipe labellisée, Molecular and Cellular Genetic Center, CNRS UMR 5534, University of Lyon, 69622 Villeurbanne, France.
Biol Cell. 2003 Oct;95(7):425-36. doi: 10.1016/s0248-4900(03)00072-8.
Netrins are secreted proteins that play a crucial role in neuronal migration and in axon guidance during the development of the nervous system. Netrin-1 has been shown to interact with the transmembrane receptors DCC and UNC5H and these receptors appeared of key importance in mediating the chemotropic activity of netrin-1. Before the discovery of DCC as a netrin-1 receptor, the gene encoding DCC was proposed as a putative tumor suppressor gene because one DCC allele was deleted in roughly 70% of colorectal cancers and its expression was often reduced or absent in colorectal cancer tissues. A putative explanation for such dual roles has recently emerged with the observation that DCC belongs to the growing family of dependence receptors. Such receptors share the property of inducing apoptosis in the absence of ligand, hence creating a cellular state of dependence on the ligand. The other netrin-1 receptors UNC5H were also subsequently proposed to be dependence receptors, suggesting that netrin-1 may not only be a chemotropic factor for neurons but also a survival factor. We describe here netrin-1 and its receptors, together with the molecular signaling pathways initiated upon netrin-1 binding or upon netrin-1 withdrawal leading respectively to axonal/neuronal guidance or cell death induction. We then conclude to the possible roles of DCC and UNC5H pro-apoptotic activities in both nervous system development and tumorigenesis.
Netrins是分泌蛋白,在神经系统发育过程中的神经元迁移和轴突导向中起关键作用。已表明Netrin-1与跨膜受体DCC和UNC5H相互作用,这些受体在介导Netrin-1的趋化活性方面显得至关重要。在发现DCC作为Netrin-1受体之前,编码DCC的基因被认为是一个假定的肿瘤抑制基因,因为在大约70%的结直肠癌中一个DCC等位基因被缺失,并且其在结直肠癌组织中的表达常常降低或缺失。最近,随着观察到DCC属于不断增加的依赖受体家族,对这种双重作用的一种假定解释出现了。这类受体具有在没有配体时诱导细胞凋亡的特性,从而产生对配体的细胞依赖状态。随后,其他Netrin-1受体UNC5H也被认为是依赖受体,这表明Netrin-1不仅可能是神经元的趋化因子,也是一种生存因子。我们在此描述Netrin-1及其受体,以及Netrin-1结合或Netrin-1撤出后分别引发的导致轴突/神经元导向或细胞死亡诱导的分子信号通路。然后我们总结了DCC和UNC5H促凋亡活性在神经系统发育和肿瘤发生中的可能作用。