Developing opto- and chemogenetic mice models to probe the role of CSF-contacting neurons in the central nervous system.

In vertebrate, neurons in contact with the CSF, also known as medullo-spinal CSF-contacting neurons (CSF-cNs), can be found along the whole length of the central canal. They represent a unique and conserved neuronal population throughout the vertebrate realm with a characteristic morphology and a selective expression of the Polycystin Kidney Disease 2-Like 1 (PKD2L1) channels, an isoform of the ‘transient receptor potential (TRP)’ superfamily. Recent studies conducted in the Zebrafish larvae and the Lamprey indicate that spinal CSF-cNs play a pivotal role in the neuromodulatory control of simple, rhythmic motor activity. Therefore, they were suggested to represent a novel sensory system intrinsic to the central nervous system.
Mammalian and lower vertebrate CSF-cNs appear to share common cellular properties and activation pathways but how this activity maps onto function in the intact central nervous system of higher order mammals remains unknown. To ultimately answer this fundamental question regarding CSF-cNs function in the mammalian central nervous system, one would need to demonstrate the function of CSF-cNs at the behavioural level and therefore conduct specific tests while selectively manipulating CSF-cNs in vivo. This in vivo investigation and manipulation of CSF-cNs activity appear challenging because of the low accessibility of the neuronal population in the mammalian spinal cord. Nevertheless, the recent developments of modern molecular tools such as opto- and chemogenetic allows the expression in one specific neuronal population of proteins that can subsequently be activated either using light stimuli (photoactivation or inhibition) or following injection of selective synthetic compounds.
For the proposed project, the student will contribute to the development of opto- and chemogenetic mice models. Viral constructs coding for photoactivable or DREAADs proteins will be injected into PKD2L1-Cre transgenic mice to selectively drive their expression in CSF-cNs (Cre-Lox technology). Following infection and expression of the protein of interest, electrophysiological recordings using the patch-clamp technique will be performed in acute spinal cord slices to assess and characterise the effect of CSF-cN photo- or chemoactivation on their physiology. This initial in vitro approach will represent the proof of concept of the models and will be crucial before developing ex-vivo or in vivo models to assess the functional role of CSF-cNs in a more integrated context.
Experimental procedures:
• Targeted viral infection an expression of opto- and chemogenetic tools in mice.
• Patch-clamp recordings on acute spinal cord slices combined to photo- and chemostimulation.
• Development of ex-vivo spinal cord preparations (whole spinal cord or hemisection).

Share the offer on :