Hall B K, Ekanayake S
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Int J Dev Biol. 1991 Dec;35(4):367-87.
During neurulation, neural crest cells migrate to many regions of the body to give rise to a wide variety of cell types. Many premigratory neural crest cells are pluripotent, their potency for differentiation being gradually restricted as they migrate along definite pathways and interact with factors present in the microenvironment. Effects of growth factors on these cells have been discussed in the present review. Mediation of growth factors in differentiation varies with the cell type. Growth factors exert a direct influence on the differentiation of neural and other related neural crest-derived tissues such as endocrinal tissues but evidence for such influences on neural crest-derived mesenchymal tissues is limited. For example, NGF, BDNF, and other factors present in neural tube extracts and glioma cell conditioned medium are essential for the differentiation of sensory neurons. Similarly, NGF, insulin, IGFs and possibly other undescribed factors are necessary for the differentiation of sympathetic neurons. IGFs also enhance the proliferation of mesenchymal derivatives of both neural crest and mesodermal origin. Glucocorticoid-mediated differentiation of neural crest-derived chromaffin endocrine cells that are ontogenetically closely related to sympathetic neurons can be inhibited by NGF, and chromaffin cells can be induced to express the neuronal phenotype by NGF. Some growth factors, such as NGF, act on neural crest- and not on placodally-derived neurons, whether the former are sensory or sympathetic. Placodal sensory neurons possess NGF receptors, but only display a limited response to NGF, perhaps because of low affinity of the receptors. Other growth factors, such as BDNF, selectively act upon sensory neurons, whether neural crest- or placodally-derived. Although extracellular matrix products play a role in initiating the differentiative process, signals from growth factors are necessary for the establishment of the functionally competent phenotype of neural crest-derived neurons, a situation that does not apply for neural crest-derived mesenchymal cells. It is interactions with ECM components deposited by epithelia that govern the differentiation of mesenchymal derivatives. Growth factors do effect proliferation of mesenchymal derivatives and inhibit mesenchymal differentiation. Although direct involvement of single growth factors in transformation o f one mesenchymal phenotype to another has not been reported so far, their localization at sites of epithelial-mesenchymal interactions in palate teeth and mandible, and the ability of excess growth factors to interrupt normal development is suggestive of their possible involvement. One group of growth factors, BMPs, can influence differentiation of cartilage, including those of neural crest origin.(ABSTRACT TRUNCATED AT 400 WORDS)
在神经胚形成过程中，神经嵴细胞迁移至身体的许多区域，分化为多种细胞类型。许多迁移前的神经嵴细胞具有多能性，随着它们沿着特定路径迁移并与微环境中的因子相互作用，其分化潜能逐渐受到限制。本综述讨论了生长因子对这些细胞的影响。生长因子在分化过程中的介导作用因细胞类型而异。生长因子对神经组织以及其他相关的神经嵴衍生组织（如内分泌组织）的分化有直接影响，但对神经嵴衍生的间充质组织的影响证据有限。例如，神经管提取物和胶质瘤细胞条件培养基中存在的神经生长因子（NGF）、脑源性神经营养因子（BDNF）及其他因子对感觉神经元的分化至关重要。同样，NGF、胰岛素、胰岛素样生长因子（IGFs）以及可能其他未描述的因子对交感神经元的分化也是必需的。IGFs还能增强神经嵴和中胚层来源的间充质衍生物的增殖。糖皮质激素介导的与交感神经元在个体发生上密切相关的神经嵴衍生嗜铬内分泌细胞的分化可被NGF抑制，并且NGF可诱导嗜铬细胞表达神经元表型。一些生长因子，如NGF，作用于神经嵴衍生的神经元而非基板衍生的神经元，无论前者是感觉神经元还是交感神经元。基板感觉神经元拥有NGF受体，但对NGF仅表现出有限的反应，这可能是由于受体亲和力较低。其他生长因子，如BDNF，选择性地作用于感觉神经元，无论其是神经嵴衍生的还是基板衍生的。尽管细胞外基质产物在启动分化过程中起作用，但生长因子发出的信号对于建立神经嵴衍生神经元的功能胜任表型是必需的，而这种情况不适用于神经嵴衍生的间充质细胞。与上皮细胞沉积的细胞外基质成分的相互作用控制着间充质衍生物的分化。生长因子确实会影响间充质衍生物的增殖并抑制间充质分化。尽管目前尚未报道单一生长因子直接参与一种间充质表型向另一种间充质表型的转化，但它们在腭、牙齿和下颌骨的上皮 - 间充质相互作用部位的定位，以及过量生长因子干扰正常发育的能力表明它们可能参与其中。一组生长因子，即骨形态发生蛋白（BMPs），可影响软骨的分化，包括那些神经嵴来源的软骨。（摘要截选至400字）
