Development of next-generation light-gated inhibitory ion channels to probe somatosensory integration in the Drosophila nociceptive circuit in vivo
Participants:
1) Peter Soba (PI; University of Hamburg), coworker:
2) Simon Wiegert (PI; University of Hamburg), coworker:
Abstract:
Development of next-generation light-gated inhibitory ion channels to probe somatosensory integration in the Drosophila nociceptive circuit in vivo
Optogenetic control of neuronal activity has revolutionized neuroscience research as it allows for specific manipulation of neuronal networks and behaviour in vivo. Constant new developments have brought forth a series of Channelrhodopsin-variants with a wide variety of kinetics and activation spectra that allow faithful light induced action potential generation in neurons and precise activation of neuronal circuits. However, it is often more informative to selectively silence a specific population of neurons in order to understand their role in the network. Such optogenetic silencing tools have lagged behind the activating tools in three critical aspects: efficiency, specificity and activation wavelength versatility. The recent development of a new class of light-gated anion channels (Chloride conducting ChRs, ‘ChloCs’) by us and others and the discovery of natural anion channel rhodopsins potentially overcome many limitations of the established tools Halorhodopsin and Archaeorhodopsin.
Especially in Drosophila, a key model organism in neuroscience research, the commonly used tools Halorhodopsin and Archaeorhodopsin show very limited efficiency. Drosophila larvae are in principle ideally suited for full optogenetic control of defined network components due to their transparency, advanced genetic accessibility and well characterized behavioural and physiological readouts.
We therefore propose to develop optimized light-gated anion channels to investigate sensory integration in a multimodal network in Drosophila in vivo. We will use them to silence individual neuronal classes during behavioural analyses and to combine them with optogenetic excitation and calcium imaging in vivo. For this purpose we will generate: 1. light-gated anion channels activated at red-shifted wavelengths that do not interfere with behaviour by confounding visual stimulation (>600nm) and allow acute neuronal inhibition of non-transparent animals, e.g. adult Drosophila. 2. light-gated anion channels compatible with CsChrimson or ChR2 mediated neuronal activation for simultaneous activation/inactivation studies. 3. Switchable light-gated anion channels to precisely control silencing in time and to allow for continuous silencing in the absence of light.
We will then address somatosensory encoding of nociception, which is an evolutionary conserved mechanism to detect and avoid harmful environmental stimuli. Drosophila larvae respond to a variety of harmful stimuli, including noxious touch, with a stereotyped escape response. Nociceptive escape behaviour is strongly influenced by simultaneous innocuous cues. However, it is poorly understood how multimodal stimuli are integrated in the nociceptive circuit at cellular level to modulate behavioural responses. Our new set of inhibitory optogenetic tools will facilitate the detailed dissection of somatosensory integration and escape responses in Drosophila, and eventually, of similar networks in a large variety of model organisms.
Publications Soba:
Soba P*, Han C, Zheng Y, Perea D, Miguel-Aliaga I, Jan LY, Jan YN*. (2015)The Ret receptor regulates sensory neuron dendrite growth and integrin mediated adhesion. Elife 2015 Mar 12;4;e05491 (*co-corresponding author)
Jiang N, Soba P, Parker E, Kim CC, Parrish JZ (2014) The microRNA bantam regulates a developmental transition in epithelial cells that restricts sensory dendrite growth. Development 141:2657-2668
Han C, Wang, D, Soba P, Zhu S, Jan LY, Jan YN (2012) Integrins are Essential for Repulsion-mediated Dendritic Spreading of Drosophila Sensory Neurons by Restricting Dendrites in a Two-dimensional Space. Neuron 73:64-78.
Soba P*, Zhu S*, Emoto K, Younger S, Yang SJ, Yu HH, Lee T, Jan LY, Jan YN (2007) Drosophila sensory neurons require Dscam for dendritic self-avoidance and proper dendritic field organization. Neuron 54:403-16 (*equal contribution)
Soba P*, Eggert S., Wagner K., Zentgraf H, Siehl K, Kreger S, Loewer A, Langer A, Merdes G, Paro R, Masters CL, Muller U, Kins S, Beyreuther K (2005) Homo- and heterodimerization of APP family members promotes intercellular adhesion. Embo J 24:3624-34 (*corresponding author)
Publications Wiegert:
Wiegert, J.S., and Oertner, T.G. (2016). How (not) to silence long-range projections with light. Nat Neurosci (in press).
Wietek, J., Beltramo, R., Scanziani, M., Hegemann, P., Oertner, T.G., Wiegert, J.S. (2015). An improved chloride-conducting channelrhodopsin for light-induced inhibition of neuronal activity in vivo. Sci Rep 5:14807
Wietek, J.*, Wiegert, J.S.*, Adeishvili, N., Schneider, F., Watanabe, H., Tsunoda, S., Vogt, A., Elstner, M., Oertner, T.G., Hegemann, P. (2014). Conversion of Channelrhodopsin into a light-gated chloride channel. Science 344 (6182): 409-412, *first 2 authors equally contributing
Wiegert, J.S. and Oertner , T. G. (2013). Long-term depression selectively eliminates weakly integrated synapses. Proc Natl Acad Sci USA 110(47), E4510-E4519.
Huber, D., Gutnisky, D.A., Peron, S., O'Connor, D.H., Wiegert, J.S., Tian, L., Oertner, T.G., Looger, L.L., and Svoboda, K. (2012). Multiple dynamic representations in the motor cortex during sensorimotor learning. Nature 484, 473-478.