Molecular and cellular mechanisms underlying the control of gene expression by a sleep-active neuron revealed by single-cell sequencing

• Applicant: Professor Dr. Henrik Bringmann
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 536195501

Sleep is essential and supports vital physiological processes systemically in both neuronal as well as non-neuronal tissues. Sleep disorders are highly prevalent in modern societies, thus posing a massive unsolved health problem. However, despite its importance, it is not known how sleep becomes regenerative at the molecular level across different cell types. Central to the induction of sleep are sleep-active neurons that depolarize during sleep to inhibit neuronal wakefulness circuits. Sleep is evolutionarily conserved and can be studied across different animal models. Caenorhabditis elegans is advantageous for sleep research as it facilitates a molecular-mechanistic dissection of this process. We showed that sleep in C. elegans depends crucially on a single sleep-active neuron called RIS. Impairing RIS abrogates sleep and impairs protective gene expression. However, it is not known how RIS controls gene expression across different cell types, stages, or physiological states. Furthermore, the specific signaling pathways through which RIS controls gene expression are not well understood. The aim of this proposal is to understand how RIS controls gene expression at the level of single cells. For this project, we will analyze single-cell gene expression profiles across neuronal and non-neuronal tissues following genetic manipulations that impair or activate RIS. To identify core changes caused by RIS activity across different physiological contexts, this analysis will be performed during two different conditions. Specifically, arrested larvae will be compared with fed adult animals. Individual cells of both neuronal and non-neuronal tissues will be isolated using fluorescent labelling and FACS, and subjected to single-cell sequencing for transcriptome analysis. Core pathways detected in the transcriptomes will be analyzed by molecular genetics and cell biological assays to determine which factors are causal to the gene expression changes observed across different cell types. This analysis will reveal which cell types are affected by RIS, how RIS affects gene expression in specific cell types and what specific genetic pathways are controlled by RIS. This project will thus provide molecular mechanisms of how a sleep neuron controls gene expression. This work will provide a single-cell view of how a sleep-active neuron controls gene expression in an animal and a roadmap also for studying the functions of mammalian sleep neurons in controlling gene expression.

• DFG Programme: Research Grants