Gene Regulation in Lens Regeneration

摘要/摘要 晶状体再生是一种显著的现象，在脊椎动物和成年动物中， 只出现在一些尾目两栖动物中。晶状体切除术后，色素上皮细胞(PECs) 从虹膜背侧去分化，然后分化成晶状体细胞。在培养的同时 从蝾螈的腹侧虹膜或包括人类在内的其他动物的虹膜中提取的胸肌可以 在体内，特别是在成年期，这种能力仅限于 仅有几只尾龙的背侧虹膜。因此，据推测，这些黑猩猩可能 掌握了解转分化所涉及的机制的关键 在其他物种中的应用，特别是在人类中。我们之前假设过，(而且 假说是我们最初提议的核心)，即在 晶状体切除术中的背侧虹膜。如果我们能够诱使虹膜腹侧达到这样的规则，我们可能会 能够诱导无功能的腹侧虹膜再生。我们试图诱导晶状体 从腹侧虹膜再生最终是成功的。迈出了如此关键的一步，我们 然后对虹膜腹侧和背侧的基因调控进行了广泛的研究。我们有 确定了非常有趣和令人惊讶的法规。特别是，似乎是调控基因 参与晶状体再生的基因在虹膜背侧和腹侧均有表达。因此，它 似乎这两种虹膜都启动了再生事件，但不知何故，一定有一种压抑 虹膜腹侧的事件。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。其一是基因的差异表达 MicroRNAs(已知每个microRNAs可以调节数百个mRNAs)，另一个是特定的 基因抑制相关的组蛋白修饰。此外，我们的EST和详细基因 表达分析表明，几种干细胞维持因子正常 以Pcs表示。这可能表明转分化与茎的关系，并可能 对再生机制提供了前所未有的见解。处理这些问题 我们建议：1)分析在背部特异调控的miRNAs的功能 和腹侧虹膜；2)分析组蛋白修饰的作用和涉及的酶与 晶状体再生的过程和干细胞维持因子的表达与 晶状体再生的机制和能力。

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.