The long-term goal of the proposed research is to use the fruit fly, Drosophila melanogaster, as an animal model to unravel the mechanisms through which insects respond to sensory cues, ranging from changes in temperature to insect repellents. These questions are of potential relevance to the control of insect pests, since mosquitoes that spread diseases are attracted to humans through thermosensory, visual and chemical cues. Aversive temperatures and chemical repellents deter insects. Therefore, understanding the mechanisms underlying avoidance behavior may provide important insights into insect pest control. A key group of receptor proteins that sense environmental stimuli are Transient Receptor Potential (TRP) cation channels. Among the 13 Drosophila members, TRPA1 is of particular note as it is a detector for a wide array of noxious sensory inputs, including slightly warm or hot temperatures, insect repellents, and excessive light. Here, we propose to dissect the molecular, cellular and behavioral mechanisms through which TRPA1 allows larvae and adult flies to elude aversive stimuli. To accomplish our goals, we propose to employ a multidisciplinary approach, using a combination of molecular genetics, biochemistry, cell biology, electrophysiology and behavioral approaches.
Aim 1 will test the hypothesis that bright light, which larvae avoid, activates TRPA1 through a novel mechanism of light detection that is independent of a cell surface protein.
In Aim 2 we propose to test the hypothesis that TRPA1 functions as a detector that allow flies to use the daily changes in temperature to set circadian cycles of locomotor activity. The experiments proposed in Aim 3 will test hypotheses concerning the function and mechanism by which TRPA1 is activated via a thermosensory signaling cascade. This cascade represents a new mode of activation of TRP channels in contrast to the well-known direct activation of """"""""thermoTRPs"""""""" by changes in temperature.
Aim 4 is an outgrowth of the observation that TRPA1 is required for flies to avoid the insect repellent, citronellal, and this response occurs through both direct and indirect mechanisms in both mosquitoes and fruit flies. In the first part of this aim we will test the hypothesis that an additional TRPA channel functions in the aversive responses to other insect repellents (geraniol and camphor). The second part of aim 4 tests the hypothesis that G-protein coupled receptors detect repellents directly, and initiate signaling cascades that lead to indirect activation of TRP channels. The proposed studies ultimately could lead to the identification of a new generation of safer and more effective repellents to control insect-borne disease by identifying and characterizing molecular targets for such compounds.

Public Health Relevance

Insect pests that spread disease identify their human hosts, and avoid noxious environmental conditions through their ability to detect thermal, chemical and visual cues. The focus of the proposed work is to exploit the great technical advantages of the fruit fly as an animal model to discover molecules and mechanisms that insects use to sense environmental stimuli, with the long-term goal of using these insights to develop new strategies to control the spread of insect-borne disease.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Neurotransporters, Receptors, and Calcium Signaling Study Section (NTRC)
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Sesma, Michael A
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University of California Santa Barbara
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Santa Barbara
United States
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Venkatachalam, Kartik; Luo, Junjie; Montell, Craig (2014) Evolutionarily conserved, multitasking TRP channels: lessons from worms and flies. Handb Exp Pharmacol 223:937-62
Liu, Sha; Lamaze, Angelique; Liu, Qili et al. (2014) WIDE AWAKE mediates the circadian timing of sleep onset. Neuron 82:151-66
Liman, Emily R; Zhang, Yali V; Montell, Craig (2014) Peripheral coding of taste. Neuron 81:984-1000
Li, Zhengzheng; Ni, Jinfei D; Huang, Jia et al. (2014) Requirement for Drosophila SNMP1 for rapid activation and termination of pheromone-induced activity. PLoS Genet 10:e1004600
Stefan, Christopher P; Zhang, Nannan; Sokabe, Takaaki et al. (2013) Activation of an essential calcium signaling pathway in Saccharomyces cerevisiae by Kch1 and Kch2, putative low-affinity potassium transporters. Eukaryot Cell 12:204-14
Lee, Youngseok; Montell, Craig (2013) Drosophila TRPA1 functions in temperature control of circadian rhythm in pacemaker neurons. J Neurosci 33:6716-25
Fowler, Melissa A; Montell, Craig (2013) Drosophila TRP channels and animal behavior. Life Sci 92:394-403
Shen, Wei L; Kwon, Young; Adegbola, Abidemi A et al. (2011) Function of rhodopsin in temperature discrimination in Drosophila. Science 331:1333-6
Hofmann, Thomas; Chubanov, Vladimir; Chen, Xiaodi et al. (2010) Drosophila TRPM channel is essential for the control of extracellular magnesium levels. PLoS One 5:e10519
Kwon, Young; Kim, Sang Hoon; Ronderos, David S et al. (2010) Drosophila TRPA1 channel is required to avoid the naturally occurring insect repellent citronellal. Curr Biol 20:1672-8

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