Gene Regulation in Lens Regeneration

摘要/摘要 透镜再生是一个值得注意的现象，在脊椎动物和成年期， 只出现在某些有尾目两栖动物身上晶状体切除术后，色素上皮细胞（佩奇） 从背侧虹膜去分化并随后分化成透镜细胞。虽然培养 来自蝾螈腹侧虹膜或其他动物（包括人类）虹膜的佩奇可以 在体内，特别是在成年期，这种能力仅限于透镜。 仅少数有尾目动物的背侧虹膜佩奇。因此，有人推测，这些有尾目动物可能 掌握着理解转分化机制的关键， 应用于其他物种，尤其是人类。我们之前假设，（并且 假设是我们最初建议的核心），在这个过程中必须有独特的监管事件。 晶状体切除术后的虹膜背侧。如果我们能诱导腹侧虹膜进行这样的调节， 能够诱导功能不全的腹侧虹膜再生我们试图诱导透镜 腹侧虹膜的再生最终成功。在迈出了如此关键的一步之后，我们 然后对腹侧和背侧虹膜的基因调控进行了广泛的研究。我们有 发现了非常有趣和令人惊讶的规则。特别是调控基因， 参与透镜再生的基因在背侧和腹侧虹膜中都有表达。因此 似乎这两个虹膜启动再生的事件，但不知何故，必须有一个压抑的 事件发生在腹侧虹膜。为了解决这个问题，我们将注意力转向全球基因组签名。 我们有证据表明大规模监管的两个罪魁祸首。一是差异表达， microRNA（已知每一种都调节数百种mRNA），另一种是特异性的 基因抑制相关的组蛋白修饰。此外，我们的EST和详细的基因 表达分析显示，几种干细胞维持因子通常 以佩奇表示。这可能表明转分化与干性的关系， 提供了关于再生机制的前所未有的见解。为了解决这些问题， 我们的目的是：1）分析miRNAs的功能，miRNAs在背侧海马中特异性调控， 2）分析组蛋白修饰和相关酶在视网膜色素变性中的作用。 透镜再生过程和3）干细胞维持因子的表达与 透镜再生的机制和能力。

Summary/Abstract Lens regeneration is a remarkable phenomenon, which, among vertebrates and during adulthood, occurs only in some urodele amphibians. Upon lentectomy, the pigmented epithelial cells (PECs) from the dorsal iris dedifferentiate and subsequently differentiate into lens cells. While cultured PECs from the ventral iris of the newt or from irises from other animals, including humans, can transdifferentiate to lens, in vivo and especially during adulthood, this ability is restricted to the dorsal iris PECs of a few urodeles only. It has been reasoned, therefore, that these urodeles might hold the key to understanding the mechanisms involved in transdifferentiation with possible applications in other species, especially in humans. We hypothesized previously, (and that hypothesis was the core of our initial proposal), that there must be unique regulatory events in the dorsal iris upon lentectomy. If we could then coax the ventral iris to such regulation we might be able to induce regeneration from the incompetent ventral iris. Our attempts to induce lens regeneration from the ventral iris were eventually successful. Having made such a crucial step, we then performed extensive studies on gene regulation in the ventral and dorsal iris. We have identified very interesting and surprising regulation. In particular, regulatory genes that seemingly are involved in lens regeneration are expressed in both dorsal and ventral irises. Therefore, it seems that both irises initiate the events of regeneration, but somehow there must be a repressive event in the ventral iris. To address this issue we turned our attention to global genomic signatures. We have evidence of two culprits of large-scale regulation. One is differential expression of microRNAs (each one of them is known to regulate hundreds of mRNAs) and the other is specific gene repression-associated histone modifications. Furthermore, our EST and detailed gene expression analysis have revealed that several stem cell-maintaining factors are normally expressed in PECs. This might indicate a relationship of transdifferentiation to stemness and could provided unprecedented insights about the mechanisms of regeneration. To approach these issues we propose to: 1) Analyze the function of miRNAs, which are specifically regulated in the dorsal and ventral iris; 2) Analyze the role of histone modifications and the involved enzymes in relation to the process of lens regeneration and 3) correlate the expression of stem cell-maintaining factors to the mechanisms and ability of lens regeneration.