Lens-forming competence in the epidermis of Xenopus laevis during development
Lens-forming competence in the epidermis of Xenopus laevis during development
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DOI：
10.1002/jez.a.138
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发表时间：
2005-01-01
影响因子：
2.8
通讯作者：
Cannata, SM
中科院分区：
文献类型：
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作者：
Arresta, E;Bernardini, S;Cannata, SM
在幼虫X.在玻璃体腔中存在的诱导因子的影响下再生透镜的能力局限于外角膜和角膜周表皮（Lentogenic Area，LA）。然而，在早期胚胎中，整个外胚层能够对幼虫眼形成透镜细胞的诱导因子作出反应。在之前的论文中，Cannata等人（2003）证明，LA中晶状体形成能力的持续性是早期信号导致推定LA中晶状体形成偏倚和来自眼睛的晚期信号导致角膜发育的结果。本文分析了1）在发育过程中，靠近LA（头部表皮）和远离LA（侧部表皮）的外胚层区域的晶状体形成能力的降低，2）头部表皮和侧部表皮对移植到这些表皮区域下方的眼睛释放的晶状体能力促进因子的响应能力，以及3）负责移植眼睛的促进效果的眼睛成分。通过将外胚层或表皮的碎片植入宿主蝌蚪的玻璃体腔中并通过评估对单克隆抗体抗晶状体呈阳性的植入物的百分比来获得结果。这些结果表明，晶状体形成能力的侧翼地区是在胚胎阶段30/31丢失，并通过眼睛移植弱恢复;然而，晶状体形成能力的头部地区是在幼虫阶段48丢失，并通过眼睛移植强烈恢复。作者假设，在发育过程中，LA外的头部外胚层通过低水平的相同信号获得LA，这些信号负责维持幼虫角膜和角膜周表皮中的晶状体形成能力。在这一假设中，低水平的这些信号减缓了头部外胚层中晶状体形成能力的降低，并使头部表皮比侧部表皮对移植眼释放的促进因子的作用更敏感。在去除某些成分的眼移植后获得的结果表明，透镜和视网膜是这些促进因素的主要来源。免疫组化检测53期幼虫46期眼移植后的表皮中FGFR-2（bek变体）蛋白的表达，结果表明眼移植增加了头表皮中FGFR-2蛋白的表达，但侧腹表皮中FGFR-2蛋白的表达没有增加，这表明眼移植提高了X.表皮的炎症反应可能与反应组织中存在活化的FGF受体系统有关。(C)2005 Wiley-Liss，Inc.
In larval X. laevis the capacity to regenerate a lens under the influence of inductive factors present in the vitreous chamber is restricted to the outer cornea and pericorneal epidermis (Lentogenic Area, LA). However, in early embryos, the whole ectoderm is capable of responding to inductive factors of the larval eye forming lens cells. In a previous paper, Cannata et al. (2003) demonstrated that the persistence of lens-forming competence in the LA is the result of early signals causing lens-forming bias in the presumptive LA and of late signals from the eye causing cornea development. This paper analyzes 1) the decrease of the lens-forming capacity in ectodermal regions both near LA (head epidermis) and far from LA (flank epidermis) during development, 2) the capacity of the head epidermis and flank epidermis to respond to lens-competence promoting factors released by an eye transplanted below these epidermal regions, and 3) the eye components responsible for the promoting effect of the transplanted eye. Results were obtained by implanting fragments of ectoderm or epidermis into the vitreous chamber of host tadpoles and by evaluating the percentage of implants positive to a monoclonal antibody anti-lens. These results demonstrated that the lens-forming competence in the flank region is lost at the embryonic stage 30/31 and is weakly restored by eye transplantation; however, lens-forming competence in the head region is lost at the larval stage 48 and is strongly restored by eye transplantation. The authors hypothesize that during development the head ectoderm outside the LA is attained by low levels of the same signals that attain the LA and that these signals are responsible for the maintenance of lens-forming competence in the cornea and pericorneal epidermis of the larva. In this hypothesis, low levels of these signals slacken the decrease of the lens-forming competence in the head ectoderm and make the head epidermis much more responsive than the flank epidermis to the effect of promoting factors released by a transplanted eye. Results obtained after transplantation of eyes deprived of some components indicate that the lens and the retina are the main source of these promoting factors. The immunohistochemical detection of the FGFR-2 (bek variant) protein in the epidermis of stage 53 larvae submitted to eye transplantation at stage 46 showed that the eye transplantation increased the level of FGFR-2 protein in the head epidermis but not in the flank epidermis, indicating that the lens-forming competence in X. laevis epidermis could be related to the presence of an activated FGF receptor system in the responding tissue. (C) 2005 Wiley-Liss, Inc.