The need for sleep is universal. All animals do it, and sleep is very tightly regulated. The consensus view of sleep regulation involves the interaction of time-of-day driven processes and homeostatic processes. A biological daily clock signals organisms to be awake at the appropriate time of day, whereas a homeostatic process drives when, how long, and how deep animals sleep after having been awake. Although there is a good understanding of the biological clock and how it promotes wakefulness, little is known about how sleep homeostasis works. Previous studies by this group of investigators has uncovered a novel genetic tool useful for gaining understanding of this fundamental aspect of sleep regulation in mammals. However, before dissecting how sleep homeostasis works, it is necessary to identify the neurons involved in the regulation of sleep homeostasis and where in brain they are located. This project leverages the novel genetic tool, together with cutting-edge genetic and neuron-level brain imaging techniques, to identify the specific neurons that are essential for sleep homeostasis in mammals. Identification of these sleep homeostasis neurons is critical for research aimed at uncovering the neural and molecular mechanisms underlying sleep homeostasis in animals. The project also provides extensive opportunities for undergraduate students from underrepresented groups to gain hands-on research experiences, with the goal of increasing participation of members from underrepresented groups in STEM professions.
The essential neuroanatomy and subsequent mechanistic underpinnings regulating sleep homeostasis in mammals are largely unknown. The principal investigator and colleagues discovered a novel genetic tool useful for gaining understanding this fundamental aspect of sleep regulation, the mechanisms of sleep homeostasis. Specifically, the principal investigator found that mice inheriting a null Ube3a allele specifically from their mother (Ube3am-/p+) lack neuronal UBE3a expression and all known homeostatic sleep responses. The heterozygous nature of this sleep phenotype, combined with floxed Ube3a alleles that allow for either Cre-dependent loss- or rescue- of UBE3a expression, and a growing resource of transgenic lines expressing Cre recombinase in subsets of neurons coalesce into a unique opportunity to employ a behavioral genetics strategy to identify essential sleep homeostat neurons in mice. Here, the investigators use Cre-directed UBE3a loss/rescue to address three fundamental aspects of sleep homeostasis: identify which neurons are involved, when they are involved, and where they are located. The studies include optimization and implementation of UBE3a immunofluorescence detection in intact, cleared brains visualized by 3D light-sheet microscopy. The anticipated outcome of the project is genetic, behavioral, electrophysiological and anatomical identification of essential sleep homeostat neurons in mice. The findings are critical for future work aimed at dissecting the neural and molecular mechanisms underlying sleep homeostasis.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
