Unlocking the molecular and cellular mechanisms regulated by the ribonuclease Dis3L2 in Drosophila and human cell proliferation.

单个卵细胞发育成复杂的多细胞生物体需要精确控制细胞增殖。细胞增殖的调节不仅在发育过程中很重要，而且在受损组织的再生和修复以及伤口愈合过程中也是必需的。组织生长的协调对于保持不同器官的正确大小和形状也至关重要。同样，控制增殖在进化中也很重要，因为自然选择可能有利于身体某些区域（如大脑）的生长。然而，不受控制的细胞增殖是癌症的标志，许多基因参与癌症进展中涉及的生长和增殖。虽然在癌症中发生的不受控制的细胞增殖所涉及的途径是众所周知的，但控制正常的协调细胞增殖的途径还没有得到很好的研究。使用人类肾脏细胞以及果蝇，我们最近发现细胞增殖可以由一种名为Dis 3L 2的蛋白质调节。这种蛋白质的消耗或去除导致过度增殖。这些结果与人类疾病相关，因为DIS 3L 2已被证明在过度生长综合征（Perlman综合征）中突变，其中受影响的儿童比正常儿童大，具有器官（例如肾脏）的异常增大和对肾母细胞瘤（一种肾癌）的易感性。此外，高达30%的散发性肾母细胞瘤具有Dis 3L 2突变。有趣的是，Dis 3L 2也与埃塞俄比亚土著绵羊的体重和身高变化有关，这表明我们的家畜有选择性。因此，了解Dis 3L 2对组织生长发挥作用的分子机制可能与正常生长以及人类过度生长疾病有关。Dis 3L 2是一种已知的“咀嚼”和破坏指示细胞制造特定蛋白质的mRNA分子的酶。这种酶是显着的，因为它具有类似的结构和功能，在广泛的生物体，从细菌到人类。在果蝇中使用最先进的分子方法，我们发现Dis 3L 2靶向一小部分mRNA，包括编码名为“成虫盘生长因子2”（idgf 2）的生长因子的mRNA。idgf 2以前已经被证明通过一种未知的途径引起果蝇细胞的增殖。对于培养中的人肾细胞，我们已经发现DIS 3L 2的消耗导致增殖增强，并且这涉及众所周知的细胞途径。我们还不知道DIS 3L 2的mRNA靶点，它激活了人类的这种增殖途径。这些结果是新颖的，因为还没有其他研究小组解开DIS 3L 2与细胞增殖的细胞机制。该项目的具体目标是了解Dis 3L 2控制果蝇和人类肾脏细胞增殖的途径和细胞机制。我们将使用现代分子和细胞生物学方法（如用于基因编辑的CRISPR-Cas9）来剖析这种增殖途径并识别关键成分。在果蝇中，我们认为Dis 3L 2在被其他细胞因子“标记”降解后直接靶向idgf 2。我们预测，Idgf 2然后激活一个特定的细胞增强细胞增殖。在人类中，我们预测DIS 3L 2靶向另一种生长因子，该生长因子反过来激活相同的途径以促进增殖。我们有专业知识，以及分子和遗传工具来测试这些想法。在这个项目中获得的知识可能有助于癌症的治疗，并帮助我们了解正常组织生长和发育的方式。因此，该项目将为调节细胞增殖的新方法提供有价值的见解，该方法可用于开发新的治疗方法。

Development of a single egg cell into a complex multicellular organism requires exquisite control of cell proliferation. Regulation of cell proliferation is not only important during development but also required in regeneration and repair of damaged tissues and also during wound healing. Co-ordination of tissue growth is also crucial to maintain the correct size and shape of different organs. Similarly, controlled proliferation is important in evolution where growth of certain areas of the body (e.g the brain) may be favoured by natural selection. However, uncontrolled cell proliferation is a hallmark of cancer with many genes involved in growth and proliferation implicated in cancer progression. Although the pathways involved in uncontrolled cell proliferation as occurs in cancer are well known, the pathways governing normal, co-ordinated cell proliferation have not been as well studied.Using human kidney cells as well as the fruit fly Drosophila we have recently discovered that cell proliferation can be regulated by a protein named Dis3L2. Depletion or removal of this protein results in excess proliferation. These results are relevant to human disease as DIS3L2 has been shown to be mutated in an overgrowth syndrome (Perlman syndrome) where affected children are larger than normal, have abnormal enlargement of organs (e.g. kidneys) and susceptibility to Wilms' tumour (a kidney cancer). In addition, up to 30% of sporadic Wilms' tumours have mutations in Dis3L2. Interestingly, Dis3L2 has also been implicated in body weight and height variation in indigenous Ethiopian sheep, suggesting selection in our domestic animals. Therefore, understanding the molecular mechanisms whereby Dis3L2 exerts its effects on tissue growth is likely to be relevant in normal growth as well as human overgrowth diseases.Dis3L2 is an enzyme known to "chew up" and destroy mRNA molecules which instruct the cell to make particular proteins. This enzyme is remarkable in that it has a similar structure and function in a wide range of organisms, from bacteria through to humans. Using state-of-the-art molecular methods in fruit flies, we have discovered that Dis3L2 targets a small subset of mRNAs, including an mRNA encoding a growth factor named 'imaginal disc growth factor 2' (idgf2). Idgf2 has been previously shown to cause proliferation of fruit fly cells via an unknown pathway. For human kidney cells in culture, we have discovered that depletion of DIS3L2 results in enhanced proliferation, and that this involves a well known cellular pathway. We do not yet know the mRNA targets of DIS3L2 which activate this proliferation pathway in humans. These results are novel in that no other research group as yet has unravelled the cellular mechanisms linking DIS3L2 with cell proliferation. The specific aims of this project are to understand the pathways and cellular mechanisms whereby Dis3L2 controls cell proliferation in Drosophila and in human kidney cells. We will use modern molecular and cell biological methods (such as CRISPR-Cas9 for gene editing) to dissect this proliferation pathway and identify key components. In fruit flies, we think that Dis3L2 directly targets idgf2 after it has been "tagged" for degradation by other cellular factors. We predict that Idgf2 then activates a specific cellular enhance cell proliferation. In humans, we predict that DIS3L2 targets another growth factor which in turn activates the same pathway to promote proliferation. We have the expertise, as well as the molecular and genetic tools to test these ideas. The knowledge gained during this project may facilitate treatments for cancer as well as help us to understand the ways that normal tissues grow and develop. This project will therefore provide valuable insights into a new way of regulating cell proliferation which can be used in the development of new therapeutics.