Genetic Analysis of Nociception in Drosophila

描述（由申请人提供）：了解躯体感觉信号通路的分子机制对于找到减轻疼痛的新方法至关重要。为了发现新的伤害感受途径，我们采用了果蝇黑腹果蝇的前向遗传方法。利用幼虫对有害刺激的行为反应，我们已经确定了在机械和热伤害感受方面有缺陷的无痛基因突变。无痛在多树突状神经元中表达，其形态类似于脊椎动物的伤害性神经元，在表皮下有多个分支的裸神经突。无痛蛋白是瞬时受体电位离子通道家族的一员，其中许多与温度转导和机械转导有关。在果蝇中，三个TRPA通道被认为是热传感器；无痛通道，我们从基因上确定了热痛觉所必需的，果蝇TRPA1 （dTRPAl）通道，与热亲和性有关，第三个通道称为热应激，提供对热应激的抵抗。虽然TRP通道可以在热感觉和机械信号转导中发挥作用，但这些通道介导温度和机械刺激反应的分子机制仍然是一个谜。我们的理想定位是利用体内遗传学来了解TRP通道在机械转导和热转导中的基本原理。我们将验证三个假设：1)果蝇TRPA通道联合决定果蝇幼虫的热痛觉阈值；2)果蝇多树突感觉神经元的一个特定亚类在伤害感受中起作用；3)无痛通道的锚蛋白重复结构域对机械转导至关重要。这些研究将提供深入了解伤害感觉的分子和细胞机制，这将有助于开发治疗疼痛的干预措施。

DESCRIPTION (provided by applicant): Understanding molecular mechanisms of somatosensory signaling pathways is critical to find new methods of alleviating pain. To discover novel nociception pathways, we have taken a forward genetic approach using the fruitfly Drosophila melanogaster. Using a larval behavioral response to noxious stimuli we have identified mutants in the painless gene that are defective in mechanical and thermal nociception. Painless is expressed in multidendritic neurons which morphologically resemble vertebrate nociceptive neurons having multiply branched naked neurites beneath the epidermis. The Painless protein is a member of the Transient Receptor Potential family of ion channels, many of which have been implicated in temperature transduction and in mechanotransduction. In Drosophila, three TRPA channels have been implicated as thermosensors; the Painless channel, which we identified genetically as required for thermal nociception, the Drosophila TRPA1 (dTRPAl) channel which has been implicated in thermotaxis, and a third channel named Pyrexia that provides resistance to thermal stress. While it is clear that TRP channels can function in thermosensory and mechanical signal transduction, the molecular mechanisms responsible for mediating responses to temperature and mechanical stimuli by these channels are still a mystery. We are ideally positioned to use in vivo genetics to understand the basic principles underlying TRP channel function in mechanotransduction and in thermotransduction. We will test three hypotheses: 1) that Drosophila TRPA channels combinatorially determine the thermal nociception threshold of the Drosophila larva; 2) that a specific subclass of Drosophila multidendritic sensory neuron functions in nociception; and 3) that ankyrin repeat domains of the Painless channel are essential for mechanotransduction. These studies will provide insight into molecular and cellular mechanisms of nociception that will assist in developing therapeutic interventions for the treatment of pain.