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

将单个卵细胞发育成复杂的多细胞生物体需要对细胞增殖进行精确的控制。细胞增殖的调控不仅在发育过程中很重要，而且在损伤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是至关重要的。同样，受控的增殖在进化中也很重要，在进化中，身体的某些区域(例如大脑)的生长可能受到自然选择的青睐。然而，不受控制的细胞增殖是癌症的一个标志，许多与生长和增殖有关的基因参与了癌症的进展。尽管癌症中细胞增殖失控的途径是众所周知的，但控制正常、协调的细胞增殖的途径还没有得到很好的研究。我们最近使用人类肾脏细胞和果蝇发现，细胞增殖可以由一种名为Dis3l2的蛋白质来调节。这种蛋白质的耗尽或去除会导致过度增殖。这些结果与人类疾病有关，因为Dis3l2已被证明突变为一种过度生长综合征(Perlman综合征)，受影响的儿童比正常儿童更大，器官(如肾脏)异常增大，并易患肾母细胞瘤(肾癌)。此外，多达30%的散发性Wilms肿瘤存在Dis3l2突变。有趣的是，Dis3l2也与埃塞俄比亚本土绵羊的体重和身高变化有关，这表明我们的家畜是选择的。因此，了解Dis3l2对组织生长产生影响的分子机制很可能与正常生长和人类过度生长疾病有关。Dis3L2是一种已知的酶，它可以“咀嚼”并破坏指导细胞制造特定蛋白质的mRNA分子。这种酶的显著之处在于，它在从细菌到人类的各种生物体中都具有相似的结构和功能。在果蝇身上使用最先进的分子方法，我们发现Dis3l2针对一小部分mRNAs，包括编码一种名为图像盘生长因子2(Idgf2)的生长因子的mRNAs。此前研究表明，Idgf2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，我们发现Dis3l2的缺失会导致细胞增殖增强，这涉及到一条众所周知的细胞途径。我们还不知道在人类中激活这一增殖途径的Dis3l2的mRNA靶点。这些结果是新颖的，因为到目前为止还没有其他研究小组揭开Dis3l2与细胞增殖之间的联系的细胞机制。该项目的具体目标是了解Dis3l2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CRISPR-Cas9进行基因编辑)来剖析这一增殖途径，并鉴定关键成分。在果蝇中，我们认为在idgf2被其他细胞因子“标记”降解后，dis3l2直接针对idgf2。我们预测Idgf2然后激活一个特定的细胞，促进细胞增殖。在人类中，我们预测Dis3l2以另一种生长因子为靶标，该生长因子反过来激活相同的途径促进增殖。我们有专业知识，也有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会促进癌症的治疗，并帮助我们了解正常组织生长和发育的方式。因此，该项目将为调控细胞增殖的新方法提供有价值的见解，该方法可用于新疗法的开发。

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.