Identification of putative dental epithelial stem cells in a lizard with life-long tooth replacement
Identification of putative dental epithelial stem cells in a lizard with life-long tooth replacement
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DOI：
10.1242/dev.052415
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发表时间：
2010-11-01
期刊：
影响因子：
4.6
通讯作者：
Richman, Joy M.
中科院分区：
文献类型：
--
作者：
Handrigan, Gregory R.;Leung, Kelvin J.;Richman, Joy M.
大多数有齿脊椎动物，包括人类，都会更换牙齿，但人们对这个过程知之甚少。在这里，我们调查牙齿上皮干细胞是否存在于一个多齿类物种，豹壁虎（Eublepharis macularius）。由于壁虎牙齿上皮缺乏类似于哺乳动物毛囊隆起的干细胞的组织学上不同的位点，我们对幼年壁虎进行了脉冲追踪实验，以确定标记保留细胞（LRC）。我们只在牙板的舌侧检测到LRC，其增殖率低，并且不参与牙齿形态发生。舌LRC被组织成高密度的口袋接近继承层。LRC的一个子集表达Lgr5和其他基因，这些基因是哺乳动物成体干细胞的标志物。同样类似于哺乳动物干细胞，LRC似乎响应于经典Wnt途径功能的获得而增殖。我们认为，LRC在舌牙板代表一个人口的干细胞，其直系后代形成的继承层，并最终在壁虎的替代牙齿。此外，它们位于牙板的非牙齿形成侧，这意味着牙齿干细胞与可能诱导它们分化的信号隔绝。
Most dentate vertebrates, including humans, replace their teeth and yet the process is poorly understood. Here, we investigate whether dental epithelial stem cells exist in a polyphyodont species, the leopard gecko (Eublepharis macularius). Since the gecko dental epithelium lacks a histologically distinct site for stem cells analogous to the mammalian hair follicle bulge, we performed a pulse-chase experiment on juvenile geckos to identify label-retaining cells (LRCs). We detected LRCs exclusively on the lingual side of the dental lamina, which exhibits low proliferation rates and is not involved in tooth morphogenesis. Lingual LRCs were organized into pockets of high density close to the successional lamina. A subset of the LRCs expresses Lgr5 and other genes that are markers of adult stem cells in mammals. Also similar to mammalian stem cells, the LRCs appear to proliferate in response to gain of function of the canonical Wnt pathway. We suggest that the LRCs in the lingual dental lamina represent a population of stem cells, the immediate descendents of which form the successional lamina and, ultimately, the replacement teeth in the gecko. Furthermore, their location on the non-tooth-forming side of the dental lamina implies that dental stem cells are sequestered from signals that might otherwise induce them to differentiate.