Gene Regulation in Lens Regeneration

描述(申请人提供)：晶状体再生是一种值得注意的现象，在脊椎动物和成年期，只发生在一些尾目两栖动物中。晶状体摘除后，虹膜背侧的色素上皮细胞(PECs)去分化，随后分化为晶状体细胞。虽然在体内，特别是在成年期间，培养出的来自纽鸟腹侧虹膜或来自包括人类在内的其他动物的虹膜的胸肌可以转化为晶状体，但这种能力仅限于少数尾目动物的背侧虹膜胸肌。因此，据推测，这些尾类可能是理解转分化机制的关键，并可能应用于其他物种，特别是人类。我们先前假设(这一假设是我们最初建议的核心)，在晶状体切除术后，虹膜背侧一定有独特的调节事件。如果我们能够诱使腹侧虹膜达到这样的调节，我们也许能够诱导功能不全的腹侧虹膜再生。我们从腹侧虹膜诱导晶状体再生的尝试最终取得了成功。在迈出了如此关键的一步后，我们对虹膜腹侧和背侧的基因调控进行了广泛的研究。我们已经确定了非常有趣和令人惊讶的监管。特别是，看似与晶状体再生有关的调控基因在虹膜背侧和腹侧都有表达。因此，似乎两个虹膜都启动了再生事件，但不知何故，在虹膜腹侧肯定有一个抑制事件。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microRNAs的差异表达(已知每个microRNAs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和详细的基因表达分析表明，几种干细胞维持因子在PECs中正常表达。这可能表明了转分化与茎的关系，并可能为再生机制提供前所未有的见解。为了解决这些问题，我们建议：1)分析在虹膜背侧和腹侧特异调控的miRNAs的功能；2)分析组蛋白修饰的作用及其涉及的酶在晶状体再生过程中的作用；3)干细胞维持因子的表达与晶状体再生的机制和能力的关系。公共卫生相关性：组织再生可以通过修复受损的组织来为许多疾病提供解决方案。我们正在利用一种脊椎动物(火蜥蜴)，它可以再生器官和身体部位。我们项目的主题是眼睛晶状体的再生。我们研究的成功结果将对原发和继发性白内障以及其他相关的眼睛问题产生影响。从长远来看，对火蜥蜴再生组织机制的了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.