The role of the "sensory neuron membrane protein 1" (SNMP1) in olfactory signal detection in insects

在昆虫中，来自周围环境的化学信号触发和控制各种行为，这些行为对生存和繁殖成功至关重要。昆虫通过触角中的嗅觉感觉神经元（OSN）接收例如从同种、食物源或产卵位点发射的相关挥发性化学信号。在全代谢昆虫，特别是蛾类和黑腹果蝇中进行的研究已经证明，信息素的高灵敏度检测是通过配备有特定调谐的气味受体（OR）和CD 36相关的“感觉神经元膜蛋白1”（SNMP 1）的专门OSN的亚群实现的。SNMP1在昆虫目中是保守的，并且在表达信息素受体（PR）的OSN中有助于高度敏感的反应以及快速激活和终止信息素诱导的反应。然而，SNMP1在信息素检测的主要过程中的确切作用以及其对非信息素嗅觉信号的灵敏检测的相关性是未知的。在这方面，我们最近分析的OR家族半代谢沙漠蝗，Schistocerca gregaria，揭示了一个相对较高的数量不同的OR类型与SNMP1共表达，这表明SNMP1不仅在信息素检测，但也可能发挥重要作用，在敏感的检测其他挥发性线索，如植物来源的挥发物指向有前途的觅食地。在此背景之前，拟议的项目旨在阐明SNMP1在嗅觉信号处理中的特定功能，并打算澄清SNMP1是否也需要用于检测行为相关的植物源性气味的基本问题。为此，我们将以沙漠蝗虫为模型，应用各种分子生物学、生物化学、电生理学和行为学方法来研究SNMP1对不同嗅觉信号的检测需求。此外，我们将探索SNMP1的可能的辅助受体功能，通过分析嗅觉相关配体的结合，其大的胞外结构域。由于嗅觉信号复合物和细胞内转导途径可能是OSN对行为相关嗅觉线索的高度敏感反应的基础，因此我们还将仔细研究SNMP1在触发代谢信号过程中的作用及其与嗅觉信号复合物中其他蛋白质的可能联系。

In insects, chemical signals from the surrounding trigger and control various behaviors that are of crucial importance for the survival and the reproductive success. Insects receive relevant volatile chemical signals that are for instance emitted from conspecifics, food sources or oviposition sites by olfactory sensory neurons (OSNs) in the antenna. Studies conducted in holometabolic insects, in particular moth species and Drosophila melanogaster, have demonstrated that the highly sensitive detection of pheromones is achieved by subpopulations of specialized OSNs that are equipped with a specifically tuned odorant receptor (OR) and the CD36-related “sensory neuron membrane protein 1” (SNMP1). SNMP1 is conserved across insect orders and contributes in OSNs expressing pheromone receptors (PRs) to highly sensitive responses as well as to a rapid activation and termination of pheromone-induced reactions. However, the precise role of SNMP1 in the primary processes of pheromone detection as well as its relevance for the sensitive detection of non-pheromonal olfactory signals is unknown. In this respect, our recent analysis of the OR family from the hemimetabolic desert locust, Schistocerca gregaria, revealed that a relatively high number of different OR types is co-expressed with SNMP1, suggesting that SNMP1 not solely operates in pheromone detection but also may play an important role in the sensitive detection of other volatile cues, such as plant-derived volatiles pointing to promising feeding grounds. Before this background, the proposed project aims at illuminating the specific function of SNMP1 in olfactory signal processing and intends to clarify the fundamental question whether SNMP1 is also required for a detection of behaviorally relevant plant-derived odorants. Towards this goal, we will use the desert locust as model and apply various molecular biological, biochemical, electrophysiological and behavioral approaches to investigate the requirement of SNMP1 for the detection of distinct olfactory signals. In addition, we will explore a possible co-receptor function of SNMP1 by analyzing the binding of olfactory relevant ligands to its large extracellular domain. Since olfactory signalling complexes and intracellular transduction pathways may underlie the highly sensitive responses of OSNs to behaviorally relevant olfactory cues, we moreover will scrutinize a role of SNMP1 in triggering metabotropic signalling processes and its possible association with other proteins in an olfactory signaling complex.