The Drosophila foraging gene: gene regulation, pleiotropy and plasticity

遗传学家传统上研究与基因相关的单个明确定义的功能。然而，许多基因在不同的组织中具有多种功能(多效性)，有时甚至在同一组织中也是如此。这项建议从基因调控的角度研究了基因的不同部分如何支持不同的功能。我们假设觅食基因的模块化结构和复杂性促进了它的多重功能。我们使用果蝇黑腹果蝇及其无与伦比的遗传工具。我们的努力集中在果蝇觅食基因上，该基因编码一种称为cGMP依赖蛋白激酶的信号分子。觅食基因编码了两个自然的等位变异，分别称为rover和Sitter。在觅食时，漫游者苍蝇比寄居者移动得更多，寻找的食物也更多。觅食基因有许多功能；除了觅食行为，它还调节学习和记忆、睡眠、压力反应和社会行为。在目前的资助中，我们从分子的角度阐述了觅食如何在果蝇的社会行为中实现其多效性功能。有待研究的社会行为包括：1)幼虫社会觅食：当3龄幼虫形成群体，同步向下挖掘液化食物时，幼虫社会觅食发生在高密度条件下。在低密度饲养下，寄居者和漫游者都单独觅食(单独觅食)，而在高密度饲养下，寄居者成群觅食(社会觅食)，而漫游者(和具有觅食基因的幼虫)只觅食。2)成虫社交持续时间：在群体中，成年保姆苍蝇的互动持续时间明显长于漫游者。社交隔离会缩短保姆的互动时间，但不会缩短漫游者的互动时间。遗传分析将许多成年的社会表型与觅食基因联系在一起。觅食基因是一个复杂的基因，由大约35kb的DNA组成。觅食基因产生许多基因产物，包括21个转录本和大约9个蛋白质亚型。这种觅食基因在不同物种之间是保守的，在苍蝇的整个发育和成虫过程中，可以在多个系统、组织和细胞中找到。在目前的提案中，我们的目标是研究：1)觅食基因的复杂结构(多个启动子、RNA转录本和蛋白质异构体)如何在果蝇的社会行为中发挥模块化作用，2)觅食基因及其表观遗传调节因子(G9a，组蛋白甲基转移酶基因，和microRNA，miR-932)之间的相互作用如何调节果蝇的社会行为，以及社会环境(例如，社会隔离)如何作用于改变这些调节模式。这项研究将建立对复杂基因如何影响多种相互作用的表型，从而在社会行为中产生正常的个体差异的全面和基础性的理解。

Geneticists traditionally study a single well-defined function associated with a gene. However, many genes have multiple functions (pleiotropy) in different tissues and sometimes even within the same tissue. This proposal investigates how different parts of a gene support different functions, from a gene regulation perspective. We hypothesize that the foraging gene's modular structure and complexity facilitates its multiple functions. We use the fruit fly Drosophila melanogaster with its unsurpassed genetic tool kit. Our efforts are focused on the Drosophila foraging gene that encodes a signalling molecule called cGMP dependent protein kinase. The foraging gene encodes two natural allelic variants called rover and sitter. While foraging, rover flies move more and find more food than sitters. The foraging gene has many functions; in addition to foraging behaviour it modulates learning and memory, sleep, stress responses and social behaviours. In the present grant, we address how, from a molecular perspective, foraging accomplishes its pleiotropic functions in Drosophila social behaviours.  Social behaviours to be studied are: 1) Larval social foraging: Larval social foraging occurs under high-density conditions when 3rd instar larvae form groups who synchronize their downward digging into the liquified food. Under low-density rearing both sitters and rovers forage alone (solitary foraging) whereas under high density, sitters forage in groups (social foraging) while rovers (and larvae with the foraging gene genetically deleted) forage alone. 2) Adult social interaction duration: In groups, adult sitter flies have significantly longer interaction durations than rovers. Social isolation reduces the interaction duration of sitters but not rovers. Genetic analyses tie a number of adult social phenotypes to the foraging gene. The foraging gene is a complex gene comprising about 35kb of DNA. The foraging gene produces many gene products including 21 transcripts an approximately 9 protien isoforms.  The foraging gene is conserved across species and found in multiple systems, tissues and cells throughout development and adulthood of the fly. In the current proposal our objectives are to investigate 1) how the foraging gene's complex structure (multiple promoters, RNA transcripts and protein isoforms) play a modular role in Drosophila social behaviours and, 2) how social behaviours are regulated by interactions between the foraging gene and its epigenetic regulators (G9a, a histone methyl transferase gene, and the microRNA, miR-932), and how the social environment (e.g. social isolation) acts to change these patterns of regulation. This research will build a comprehensive and foundational understanding of how a complex gene affects multiple interacting phenotypes to generate normal individual differences in social behaviour.