Novel approaches to define tissue fusion mechanisms in embryonic development.

在人类发育过程中，组织融合方式的破坏是出生缺陷的常见原因，在英国，大约每500人中就有1人受到影响。这项研究之所以被推动，是因为尽管我们尽了最大的努力，但大多数先天性腭裂、脊柱裂和心脏缺陷等疾病的患者仍然没有确定其疾病的遗传原因。这往往影响遗传咨询和预防工作。我们也仍然不确定母亲的环境对这些疾病（例如疾病，维生素缺乏症或药物滥用）有什么影响。本研究旨在通过进行变革性研究来揭示正常组织融合所需的关键基因、细胞行为和分子系统，并为我们对这些如何被干扰的知识提供一个台阶。为了增强我们对融合的理解，我们需要实验通用和适当的模型系统。我将集中在眼缺损的原因，主要的遗传性失明的原因所产生的融合缺陷的视裂闭合（OFC）在眼睛在怀孕的前7周。这种缺陷会在视网膜和视神经中留下一个无法治愈或修复的永久性间隙。我的小组的工作已经建立了鸡眼作为一个强大的和易于处理的新模型融合，因为一个独特的组合功能：（i）它非常类似于OFC在人类;（ii）实验可以在鸡蛋内进行;（iii）鸡眼足够大，以准确地解剖融合组织，以进一步实验。在罗斯林研究所，我们还开发了独特的带有荧光细胞的转基因鸡，我可以在整个OFC中观察它们的行为，并且我可以选择性地分离特定的细胞，以揭示它们独特的基因表达谱。这项工作将继续结合联合收割机这些新技术与其他尖端技术在RNA测序，基因网络分析，细胞行为建模，以产生一个强大的和准确的框架OFC和组织融合的信息。我们的研究已经确定了几个关键基因参与融合在胚胎眼，腭和内耳。我的小组将通过产生直接参与OFC融合过程的细胞的分子特征的更精细的视图来进一步理解这些基因对融合的贡献。我还将确定它们丢失或失调的后果，以了解更多关于融合过程中特定细胞行为的遗传驱动因素和修饰剂。理解Netrin-1基因的功能是我们工作的关键部分，因为我最近表明，这是不同物种正常OFC的重要因素，也是其他发育融合环境（眼睛，耳朵和腭）所必需的。我将揭示Netrin-1和其他融合特异性基因如何调节融合，以及如何受到全基因组网络的调控，使我们能够更好地了解在人类患者中发现的突变的生物学后果，并准确预测新的致病候选基因，以及随后非遗传因素对融合中基因表达调控的影响。这是一个强大的工具组合，可以改变融合生物学。它将为特定分子和途径在胚胎发生过程中如何发挥作用，以及这些分子和途径的破坏如何影响遗传和细胞程序，直接或间接导致发育融合缺陷提供有价值的信息。我揭示的信息将帮助临床医生发现新的致病突变，并提供证据支持受影响家庭的遗传咨询。从长远来看，我的系统将确定常见的组织融合机制，然后母体环境如何影响融合缺陷的原因，并帮助确定降低其发生率的策略。

Disruptions to how tissues fuse together during human development is a common cause of birth defects, affecting approximately 1 in 500 people in the UK. This research has been prompted because despite our best efforts, most patients born with problems such as cleft palate, spina bifida, and heart defects still don't have the genetic cause of their disorder identified. This often impacts genetic counselling and efforts towards prevention. We also remain unsure what impacts maternal environment have on these conditions (e.g. illness, vitamin deficiency, or substance abuse). This research aims to address these by performing transformative studies to reveal the key genes, cell behaviours, and molecular systems required for normal tissue fusion, and provide a step-change in our knowledge of how these can be perturbed.To enhance our understanding of fusion, we require experimentally versatile and appropriate model systems. I will focus on the causes of ocular coloboma, the leading inherited cause of blindness arising from a fusion defect of optic fissure closure (OFC) in the eye in the first 7 weeks of pregnancy. This defect leaves a persistent gap in the retina and optic nerve which cannot be cured or repaired. My group's work has established the chick eye as a powerful and tractable new model for fusion because of a unique combination of features: (i) it closely resembles OFC in humans; (ii) experiments can be performed inside the egg; and (iii) chick eyes are sufficiently large to accurately dissect fusing tissues for further experimentation. At Roslin Institute we have also developed unique transgenic chickens with fluorescent cells whose behaviours I can observe throughout OFC, and from which I can selectively isolate specific cells to reveal their unique gene expression profiles. This work will continue to combine these new technologies with other cutting-edge techniques in RNA sequencing, gene-network analysis, and cell behaviour modelling to generate a robust and accurate framework of OFC and tissue fusion information.Our research has defined several key genes involved in fusion in the embryonic eye, palate and inner ear. My group will further our understanding of these genes contribution to fusion by generating a more refined view of the molecular signatures for the cells directly taking part in the OFC fusion process. I will also determine the consequence of their loss or dysregulation to learn more about the genetic drivers and modifiers for specific cell behaviours during fusion. Understanding the function of the Netrin-1 gene is a key part of our work, as I have recently shown that this is an essential factor for normal OFC in diverse species, and that it is required for other developmental fusion contexts (eye, ear and palate). I will reveal how Netrin-1 and other fusion-specific genes regulate fusion and are regulated by genome-wide networks, allowing us to understand better the biological consequences of mutations identified in human patients, and to accurately predict new disease-causing candidate genes, and subsequently the effect of non-genetic factors on the regulation of gene expression in fusion.This is a powerful combination of tools to transform fusion biology. It will provide valuable information for how specific molecules and pathways function during embryogenesis, and how disruption to these can affect genetic and cellular programmes, directly or indirectly leading to developmental fusion defects. The information I reveal will help clinicians to uncover new causative mutations and provide evidence to support genetic counselling in affected families. In the longer term, my system will determine common tissue fusion mechanisms, and then how maternal environment can influence the causes of fusion defects, and help define strategies to reduce their incidence.