Gene Regulation in Lens Regeneration

描述（由申请人提供）：透镜再生是一种值得注意的现象，在脊椎动物和成年期，仅发生在一些有尾目两栖动物中。晶状体切除术后，虹膜背侧的色素上皮细胞（佩奇）去分化，随后分化为透镜细胞。虽然从蝾螈的腹侧虹膜或从虹膜从其他动物，包括人类，培养佩奇可以transdifferentiate到透镜，在体内，特别是在成年期，这种能力仅限于背侧虹膜佩奇的一些有尾目动物。因此，有理由认为，这些有尾目动物可能是理解转分化机制的关键，可能适用于其他物种，特别是人类。我们之前假设（该假设是我们最初建议的核心），晶状体切除术后背侧虹膜中必须有独特的调节事件。如果我们能诱导腹侧虹膜接受这样的调节，我们也许能从功能不全的腹侧虹膜诱导再生。我们尝试从虹膜腹侧诱导透镜再生，最终获得成功。在迈出了关键的一步之后，我们对腹侧和背侧虹膜的基因调控进行了广泛的研究。我们发现了非常有趣和令人惊讶的规则。特别是，调控基因，似乎是参与透镜再生表达在背侧和腹侧虹膜。因此，似乎两个虹膜都启动了再生事件，但不知何故，腹侧虹膜中一定有一个抑制事件。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。一个是microRNA的差异表达（已知它们中的每一个都调节数百种mRNA），另一个是特异性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表明，一些干细胞维持因子在佩奇中正常表达。这可能表明转分化与干性的关系，并可能提供有关再生机制的前所未有的见解。为了解决这些问题，我们建议：1）分析miRNAs的功能，这是特别是在背侧和腹侧虹膜; 2）分析组蛋白修饰的作用和相关酶的透镜再生的过程中和3）相关的干细胞维持因子的表达透镜再生的机制和能力。公共卫生相关性：组织再生可以通过修复受损组织来解决许多疾病。我们正在利用一种脊椎动物（蝾螈），它可以再生器官和身体部位。我们项目的主题是眼睛透镜的再生。我们研究的成功结果将对原发性和继发性白内障以及其他相关眼部问题产生影响。从长远来看，对蝾螈组织再生机制的理解最终将影响整个再生医学领域。

DESCRIPTION (provided by applicant): 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. PUBLIC HEALTH RELEVANCE: Tissue regeneration could provide solutions to many diseases by repairing the damaged tissue. We are utilizing a vertebrate animal (a salamander), which can regenerate organs and body parts. Our project's subject is regeneration of the eye lens. Successful outcome of our research will have impact in primary and secondary cataracts and other related eye problems. In the long run understanding of the mechanism whereby the salamanders regenerate their tissues will eventually impact the field of regenerative medicine as a whole.