Investigating the sexually dimorphic neural circuit in Drosophila melanogaster using behavioural genetics and structural biology

利用行为遗传学和结构生物学研究果蝇的性二态性神经回路

• 批准号: RGPIN-2014-06012
• 负责人: Leung, Adelaine
• 金额: $ 2.55万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=630011
• 关键词: Investigating; sexually; dimorphic; neural; circuit

“How does our brain govern how we behave?” has been a curiosity of mankind since the time of Hippocrates. Attempting to solve this mystery is still a monumental task as the human brain consists of close to 100 billion neurons making 100 trillion connections. How do we make sense of how such a complicated system works? To help us gain some insight into how our brain works, we turn to the common fruit fly as a model system. With only ~100,000 neurons, the fly nervous system is much simpler. Learning the underpinnings of a simple network such as a fly’s brain will provide the fundamental knowledge relevant to the operation of a larger network. Animals are born with certain instincts that ensure their survival and reproductive success. Since instincts are hard-wired, it gives us an opportunity to use genetic tools to manipulate the nervous system in order to understand how the nervous system functions to elicit a behaviour. In flies, courtship is a sex-specific complex instinctive behaviour. Males perform a series of courtship rituals (orientation, tapping, singing, licking, copulation) while females decide whether to run away or slow down and allow copulation. Requiring the use of all senses (i.e., vision, smell, and taste) and a decision process that triggers a motor output to perform the courtship rituals, male courtship behaviour is controlled by a neural network called the fruitless (fru) circuit. The fru circuit consists of ~2000 neurons in the nervous system. While the neuronal organization of this circuit is available, how each neuron functions in the context of courtship behaviour has not been fully worked out. The fru circuit is gender-specific in that some neurons are absent in females, some are present in both sexes but have different morphology, and others may have different functions in males and females. The male-form of the fru gene product (FruM) is the key protein that is responsible for the development of the fru circuit. Recently, it was discovered that FruM works with two protein factors (HDAC1 and HP1a) to fine-tune the gender property of at least two small regions of the circuit. It is not known whether the same protein factors affect other gender-specific regions of the fru circuit as well. With my unique training both in structural biology and behavioural genetics and reagents generated from my previous work that permits gene targeting to a small subsets of the fru circuit, I will be able to pursue my research program in three directions: 1) what role do these subsets of fru neurons play in courtship? 2) What factors associate with FruM to influence the development of different gender-specific regions of the circuit? 3) How does FruM interact with its binding partners in three-dimensional space to cause behavioural and morphological outcomes. In my five-year proposal, I will focus on three short-term objectives: 1) to identify fru neurons that process visual senses during courtship; 2) to evaluate the role of HDAC1 and HP1a in the gender-specific development of a small group of fru neurons isolated in our previous work; and 3) to investigate the different binding property of FruM to HDAC1 and HP1a in vitro. The significance of my research program is in the novelty of combining holistic and reductionist approaches to understand the functioning and development of the fru circuit. The unique insights developed from this combined approach will benefit the field of neurobiology of innate behaviour. The HQPs funded by this grant will become experts in a wide range of very technical experimental approaches, ensuring their competitiveness in the Canadian and international scientific workforce. The multidisciplinary research program can lead to new techniques that can be used to study animal behaviour.

“我们的大脑如何控制我们的行为？”从希波克拉底时代起就一直是人类的好奇心。试图解开这个谜团仍然是一项艰巨的任务，因为人类大脑由近1000亿个神经元组成，形成100万亿个连接。我们如何理解这样一个复杂的系统是如何工作的？为了帮助我们更深入地了解大脑是如何工作的，我们把普通的果蝇作为模型系统。只有约100，000个神经元，苍蝇的神经系统要简单得多。了解一个简单网络（如苍蝇的大脑）的基础将为更大网络的运作提供基础知识。动物与生俱来的某些本能确保了它们的生存和繁殖成功。由于本能是与生俱来的，它给了我们一个机会，利用遗传工具来操纵神经系统，以了解神经系统如何发挥作用，从而引发一种行为。在果蝇中，求偶是一种性别特异的复杂本能行为。雄性会进行一系列的求偶仪式（定向、轻拍、唱歌、舔、交配），而雌性则会决定是逃跑还是放慢速度，允许交配。需要使用所有感官（即，视觉、嗅觉和味觉）以及触发运动输出以执行求偶仪式的决策过程，雄性求偶行为由一个称为无结果（fru）回路的神经网络控制。fru回路由神经系统中的约2000个神经元组成。虽然这个回路的神经元组织是可用的，但每个神经元在求偶行为中的功能还没有完全确定。fru回路是性别特异性的，因为有些神经元在女性中不存在，有些在两性中都存在，但具有不同的形态，还有一些在男性和女性中可能具有不同的功能。fru基因产物的雄性形式（FruM）是负责fru回路发育的关键蛋白。最近，人们发现FruM与两种蛋白质因子（HDAC 1和HP 1a）一起工作，以微调电路中至少两个小区域的性别特性。同样的蛋白质因素是否也影响到fru回路的其他性别特异性区域还不清楚。凭借我在结构生物学和行为遗传学方面的独特训练，以及从我以前的工作中产生的允许基因靶向fru回路的一小部分的试剂，我将能够在三个方向上继续我的研究计划：1）这些fru神经元的子集在求爱中扮演什么角色？2)哪些因素与FruM相关，从而影响回路中不同性别区域的发育？3)FruM如何在三维空间中与其结合伙伴相互作用以引起行为和形态结果。在我的五年计划中，我将专注于三个短期目标：1）识别在求爱期间处理视觉感觉的fru神经元; 2）评估HDAC 1和HP 1a在我们以前的工作中分离的一小群fru神经元的性别特异性发育中的作用; 3）研究FruM与HDAC 1和HP 1a在体外的不同结合特性。我的研究计划的意义在于结合整体和还原论的方法来理解fru电路的功能和发展的新颖性。从这种结合的方法中开发的独特见解将有利于先天行为的神经生物学领域。由这笔赠款资助的HQP将成为广泛的技术性实验方法的专家，确保他们在加拿大和国际科学劳动力中的竞争力。多学科研究计划可以导致新的技术，可用于研究动物行为。