Project Portugal 2030

Summary

Here, we will uncover in an unprecedent way how the sleep-related MCH peptide regulates neuron-microglia interaction to maintain neuronal homeostasis. While the role of awake-related peptides has been highlighted by recent studies, the involvement of hypnogenic sleep factors remains unexplored. This work will shed light on the physiological role of the MCH-system and its relationship to microglia. Targeting MCH represents a novel therapeutic strategy to halt hyperexcitability and chronic inflammation at early stages of AD. The aims we propose build on published and preliminary results. We will employ cutting edge approaches, novel mouse models and will assemble a top-notch network of collaborators (see section 9 for detailed methods). Aim 1. Analyze the dynamics of Ptgs2/COX2 in different brain states and upon MCH neuron manipulation. COX2 levels are dysregulated in brains of early AD patients 45. My preliminary data shows that, at the timepoint that the MCH-system is impaired 4, Ptgs2 levels are increased in CA1 neurons from AppNL-G-F mice. Here we will study the link between awake-sleep cycles, MCH neuron activity and Ptgs2/COX2 levels. Moreover, we propose that MCH-neuron activation rescues altered levels of Ptgs2. Task 1. Study if Ptgs2/COX2 levels in CA1 pyramidal neurons are dynamically regulated across different brain states in wild-type mice. Task 2. Investigate if the activity of MCH neurons modulates Ptgs2/COX2 levels in CA1 pyramidal neurons from Pmchcre mice. Task 3. Analyze if the activity of MCH neurons renormalizes Ptgs2/COX2 levels in CA1 pyramidal neurons from AppNL-G-F mice. 2. Examine if the activity of MCH neurons impacts lipid biology. COX2 catalyzes the formation of bioactive lipids 46. Neuron-glia lipid dynamics is regulated by sleep and accumulation of lipids is observed in microglia during ageing and in AD 34,36. Here, we will investigate whether MCH is a key player orchestrating lipid dynamics between neurons and microglia. Task 4. Investigate if the activity of MCH neurons modulates lipid droplets accumulation in CA1 pyramidal neurons and microglia from Pmchcre mice. Task 5. Investigate if the activity of MCH neurons renormalizes lipid droplets accumulation in CA1 pyramidal neurons and microglia from AppNL-G-F mice. Task 6. Analyze if activation of MCH neurons modulates microglia lipid content in Appwt and AppNL-G-F mice using targeted LC-MS. 3. Study how the activity of MCH neurons affects the transcriptional profile of microglia. Transcriptional studies show that Aß promotes the transition of homeostatic microglia (HM) to disease associated microglia (DAM) 47,48. The presence of DAM is essential for plaque phagocytosis, however in the long-term they become deleterious for the brain and chronic inflammation emerges. Our preliminary data shows that MCH neuron activation increases microglia complexity, supporting the hypothesis that microglia acquire dinstinct cellular-state resembling HM. We suggest that MCH promotes a novel and unidentified REM sleep-dependent signature, essential to maintain microglia flexibility and physiological functions 42. Here, we will reveal transcriptional signature of microglia upon the activation of MCH neurons and study whether this rescues the DAM signatures of AppNL-G-F mice, restoring HM properties. Task 7. Determine if activation of MCH neurons modulates microglia cellular-state and rescues disease related signatures in Appwt and AppNL-G-F mice using scRNAseq.