Evolution of the mammalian dentate gyrus.
Evolution of the mammalian dentate gyrus.
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DOI：
10.1002/cne.23851
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发表时间：
2016-02-15
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影响因子：
--
通讯作者：
Hevner RF
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作者：
Hevner RF
齿状回（DG）是海马结构的一部分，在学习、记忆和成人神经发生中具有重要功能。与蜥脚类动物（鸟类和爬行动物）的同源区域相比，哺乳动物的 DG 更大，并且表现出性质不同的表型：（1）折叠（C 形或 V 形）颗粒神经元层，凹向门，由海马裂界定； (2)非脑室周围成人神经发生； (3)个体发育延长，涉及神经干细胞和祖细胞（NSPC）广泛的心室（基底）迁移和增殖。尽管差距仍然存在，但现有数据表明这些 DG 特征存在于所有哺乳动物目中，包括单孔类动物和有袋动物。鲸目动物（鲸鱼、海豚和鼠海豚）是个例外，其中 DG 大小、卷积和成体神经发生都经历了进化回归。简洁性表明，在干哺乳动物中，DG 的生长和卷积增加，同时发生非脑室周围的成年海马神经发生，以及 NSPC 在发育过程中的基底迁移。这些特征可能都是由进化变化引起的，这种进化变化增强了 NSPC 径向迁移出脑室周围区域的能力，可能是通过上皮-间质转化，以定殖并维持非脑室周围增殖生态位。反过来，NSPC 迁移和克隆扩张的增加可能是皮质下缘（内侧模式中心）生长的结果，皮质下缘产生 Wnt3a 等形态发生素，产生 Cajal-Retzius 神经元，并受 Lhx2 调节。最后，DG 卷积和新皮质回旋（或回旋能力）之间的相关性表明，NSPC 的腹侧迁移和增殖增强在新皮质以及古皮质的生长和折叠中发挥了变革性作用。羊膜动物的比较分析表明，哺乳动物齿状回的特点是卷积和非脑室周围的成体神经发生。通过增强胚胎齿状迁移流中的中间祖细胞（IP）和放射状胶质祖细胞（RGP）的迁移，这两种特征都出现在干哺乳动物中。
The dentate gyrus (DG), a part of the hippocampal formation, has important functions in learning, memory, and adult neurogenesis. Compared to homologous areas in sauropsids (birds and reptiles), the mammalian DG is larger and exhibits qualitatively different phenotypes: (1) folded (C- or V-shaped) granule neuron layer, concave towards the hilus, delimited by a hippocampal fissure; (2) non-periventricular adult neurogenesis; and (3) prolonged ontogeny involving extensive abventricular (basal) migration and proliferation of neural stem and progenitor cells (NSPCs). Although gaps remain, available data indicate that these DG traits are present in all orders of mammals, including monotremes and marsupials. The exception is Cetacea (whales, dolphins, and porpoises), in which DG size, convolution, and adult neurogenesis have undergone evolutionary regression. Parsimony suggests that increased growth and convolution of the DG arose in stem mammals, concurrently with non-periventricular adult hippocampal neurogenesis, and basal migration of NSPCs during development. These traits could all result from an evolutionary change that enhanced radial migration of NSPCs out of the periventricular zones, possibly by epithelial-mesenchymal transition, to colonize and maintain non-periventricular proliferative niches. In turn, increased NSPC migration and clonal expansion might be a consequence of growth in the cortical hem (medial patterning center), which produces morphogens such as Wnt3a, generates Cajal-Retzius neurons, and is regulated by Lhx2. Finally, correlations between DG convolution and neocortical gyrification (or capacity for gyrification) suggest that enhanced abventricular migration and proliferation of NSPCs played a transformative role in growth and folding of neocortex, as well as archicortex. Comparative analysis of amniotes shows that the mammalian dentate gyrus is distinguished by convolution and non-periventricular adult neurogenesis. Both features arose in stem mammals, by enhanced migration of intermediate progenitors (IPs) and radial glial progenitors (RGPs) in the embryonic dentate migration stream.