Nerve growth factor and its receptor TrkA serve as potential markers for human corneal epithelial progenitor cells
Nerve growth factor and its receptor TrkA serve as potential markers for human corneal epithelial progenitor cells
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DOI：
10.1016/j.exer.2007.09.003
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发表时间：
2008-01-01
影响因子：
3.4
通讯作者：
Pflugfelder, Stephen C.
中科院分区：
文献类型：
--
作者：
Qi, Hong;Li, De-Quan;Pflugfelder, Stephen C.
神经营养蛋白家族的成员神经生长因子（NGF）已被鉴定为支持干细胞自我更新神经系统外的重要生长因子，并且以前被证明可以刺激体内和体外刺激角膜上皮上皮增殖。在这项研究中，我们通过免疫荧光染色和相对定量的实时聚合酶链反应评估了NGF及其相应受体在人角膜和边缘组织中的表达。我们发现NGF在人类缘基底上皮中唯一表达，其两个相应的受体：高亲和力受体TRKA和低亲和力受体P75NTR。 TRKA被证明优先定位于缘缘基底上皮细胞。还发现NGF和TRKA与与干细胞相关的分子标记（药物抗性转运蛋白ABCG2和P63）共定位，但没有与分化标记物细胞角蛋白3在人类边缘的基础上皮层中。在培养的边缘上皮细胞中，发现NGF和TRKA被少数一个处缘缘上皮细胞群体优先表达。 NGF和TRKA免疫阳性亚群的某些特性（包括ABCG2和p63表达）富含假定的膜缘上皮干细胞（与整个细胞群体相比，P <0.01）。发现NGF和TRKA转录本水平的水平比角膜组织更丰富，在增殖阶段的年轻培养细胞中比在包含分化细胞的空运分层培养物中的水平更高。 NGF及其在基础上皮细胞中的两个相应受体的共表达。但不在角膜中，表明NGF可能是支撑干细胞干细胞壁the中干细胞自我更新的关键自分泌因子或旁分泌因子。在负细胞斑块之间散布的基底细胞的小簇对NGF和TRKA的空间表达表明它们是人角膜上皮祖细胞的潜在市场。 （c）2007 Elsevier Ltd.保留所有权利。
Nerve growth factor (NGF), a member of the neurotrophin family, has been identified as an essential growth factor supporting stem cell self-renewal outside the nervous system and was previously shown to stimulate corneal epithelial proliferation both in vivo and in vitro. In this study, we evaluated the expression of NGF and its corresponding receptors in the human corneal and limbal tissues, as well as in primary limbal epithelial cultures by immunofluorescent staining and relatively quantitative real-time polymerase chain reaction. We found that NGF was uniquely expressed in the human limbal basal epithelium, together with its two corresponding receptors: the high-affinity receptor TrkA and the low-affinity receptor p75NTR. TrkA was shown to preferentially localize to limbal basal epithelial cells. NGF and TrkA were also found co-localized with stem cell-associated molecular markers (drug-resistance transporter ABCG2 and p63), but not with the differentiation marker cytokeratin 3 in the human limbal basal epithelial layer. In cultured limbal epithelial cells, NGF and TrkA were found to be preferentially expressed by a small population of limbal epithelial cells. The NGF and TrkA immuno-positive subpopulations were enriched for certain properties (including ABCG2 and p63 expression) of putative limbal epithelial stem cells (P < 0.01, compared with the entire cell population). Levels of NGF and TrkA transcripts were found to be much more abundant in limbal than in corneal tissues, and in young cultured cells in the proliferative stage than in airlifted stratified cultures containing differentiated cells. The co-expression of NGF with its two corresponding receptors in limbal basal epithelial cells. but not in the cornea, suggests that NGF may function as a critical autocrine or paracrine factor supporting stem cell self-renewal in the limbal stem cell niche. The spatial expression of NGF and TrkA by small clusters of basal cells interspersed between negative cell patches suggests that they are potential markets for human corneal epithelial progenitor cells. (C) 2007 Elsevier Ltd. All rights reserved.