Mechanisms underlying homeotic function across developmental transitions

神经系统的细胞成分在基因的指导下形成并发挥作用。但是，指导神经系统形成的遗传程序如何切换到控制成年生物体中成熟神经元的生理程序呢？我们最近在果蝇身上探索了这个问题，这是现代遗传学中一个优秀的模式系统，并发现Hox基因--编码一组从昆虫到人类在进化上保守的关键发育基因--既控制着发育，也控制着成熟神经元调节行为的生理特性。因此，这个系统提供了一个很好的机会来确定特定基因在成年生物体中神经元分化和成熟过程中控制生物学的机制。这一点很重要，因为它将告诉我们细胞如何控制其内部遗传程序以经历“细胞过渡”：细胞生物学在这一点上迅速而戏剧性地变化，将“发育中”的细胞转变为最终的成熟细胞，并将其长期保留在成年生物体中。因为在根本层面上，神经元的发育和功能遵循所有动物的共同原则，我们在飞行中的工作产生的知识预计也将影响对其他物种基本神经生物学过程的理解，包括人类。该计划利用现代果蝇工具包，并结合使用基因技术来标记特定的神经元子集，称为多巴胺能神经元，这些神经元在昆虫和哺乳动物的运动控制中发挥着关键作用。通过这种方法，我们将：1)人工降低HOX基因的表达，并使用先进的细胞分选技术和现代RNA测序来确定这种处理对多巴胺能神经元遗传程序的影响，获得所有表达受HOX基因控制的基因的目录。2)然后，我们将使用上面产生的基因列表来生成和测试机制模型，以解释HOX基因如何控制多巴胺能神经元内的基因网络，从而使它们能够正常发育和发挥功能。3)在最后的工作单元中，我们将确定HOX控制下的基因如何与发育和成熟的多巴胺能神经元中特定的细胞角色相关。这项工作将有助于我们了解基因如何塑造正常动物内神经元的生物学，并有助于破译动物发育、神经生理学和行为的遗传基础。我们的研究还将有助于理解神经元一般是如何在发育和成熟的“健康”大脑中建立其身份的，为识别与神经发育和神经退行性疾病有关的变化提供一个框架。关于神经元转变基础的基础知识也有望增加干细胞生物学和再生医学领域的知识，通过人工操作将细胞带入特定的命运，以了解健康和疾病的过程。该项目源于我们对Hox基因系统的密切了解，在果蝇基因功能分析方面的良好记录，丰富的初步数据，以及我们被证明有能力研究神经元的发育和生理过程。这项工作将在苏塞克斯神经科学的高度协作和跨学科社区内开展，该中心是国际领先的神经科学研究中心，拥有50多个神经科学研究实验室，总部设在苏塞克斯园区。并将进一步受益于苏塞克斯、牛津和德国的专家合作者的投入，他们将在项目具体方面的发展过程中分享他们的技术专长。总而言之，这使我们处于一个理想的位置，可以在赠款期限内成功发展这一项目。

The cellular components of the nervous system form and function under the directions of the genes. But how does the genetic program that guides the formation of the nervous system switch into the program that controls the physiology of mature neurons in adult organisms? We have recently explored this question in the fruit fly Drosophila melanogaster, an excellent model system in modern genetics, and discovered that the Hox genes - which encode a group of key developmental genes evolutionarily conserved from insects to humans - control both the development, as well as the physiological properties of mature neurons modulating behaviour. This system, therefore, offers an excellent opportunity to determine the mechanisms by which specific genes control the biology of neurons during their differentiation and mature life in the adult organism. This is important given that it will inform us on how cells control their internal genetic programmes to undergo 'cellular transitions': points at which the biology of cells changes quickly and dramatically, transforming a cell 'under development' into the final, mature cell that will remain in the adult organism for a long time. Because at a fundamental level, neuronal development and function follow common principles across all animals, knowledge produced from our work in the fly is expected to impact the understanding of the fundamental neurobiological processes in other species too, including humans. The plan exploits the modern Drosophila toolkit and combines the use of genetic techniques to label a specific subset of neurons, termed dopaminergic neurons, which play key roles in movement control in insects as well as in mammals. Through this approach we will:1) Artificially reduce the expression of the Hox genes, and use advanced cell-sorting techniques and modern RNA sequencing to determine the effects of this treatment on the genetic programme of dopaminergic neurons changes, obtaining a catalogue of all genes whose expression is under Hox gene control. 2) We will then use the gene lists produced above to generate and test mechanistic models to explain how the Hox genes might control gene networks within dopaminergic neurons, thus allowing them to develop and function normally. 3) In the last unit of work we will determine how genes under Hox-control relate to specific cellular roles in developing and mature dopaminergic neurons.The work will thus help us understand how genes mould the biology of neurons within the normal animal, and contribute to decode the genetic basis of animal development, neurophysiology and behaviour. Our research will also contribute to the understanding of how neurons in general establish their identity within the developing and mature 'healthy' brain, providing a framework for the identification of changes linked to neuro-developmental and neurodegenerative diseases. The basic knowledge on the underpinnings of neuronal transitions is expected to also add to the field of stem cell biology and regenerative medicine, where cells are taken into specific fates via artificial manipulations to understand processes in health and disease.The project stems from our close understanding of the Hox gene system, strong track record in the analysis of gene function in flies, a wealth of preliminary data, and our proved ability to investigate developmental and physiological processes in neurons.The work will be developed within the highly collaborative and interdisciplinary community of Sussex Neuroscience, an internationally-leading centre for neuroscience research with more than 50 neuroscience research labs based on the Sussex campus, and will further benefit from the input of expert collaborators in Sussex, Oxford and Germany who will be sharing their technical expertise during the development of specific aspects of the project. Altogether, this puts us in an ideal position to develop this project successfully within the period of the grant.