Greotti, E. | bioRxiv Science

bioRxiv2025

The extracellular ATP/P2X7R signaling axis drives early neuroinflammation and neuronal hyperexcitability in an Alzheimer's disease mouse model

Neuroinflammation and synaptic dysfunction are emerging as early and potentially causative events in Alzheimers disease (AD), yet their molecular triggers remain elusive. Here, we identify extracellular ATP (eATP), a major damage-associated molecular pattern, and its purinergic receptor P2X7 (P2X7R) as pivotal drivers of early pathology in AD mice. In vivo bioluminescence imaging revealed a significant cortical accumulation of eATP in AD mice as early as 2 months of age--before amyloid plaque deposition and cognitive impairment. This increase is associated with inflammasome activation, pro-inflammatory cytokine production, microglia reactivity, aberrant synaptic pruning and perineuronal net degradation. Strikingly, genetic deletion of P2X7R rescues these alterations. Two-photon calcium imaging further demonstrates that P2X7R knockout counteracts AD-related neuronal hyperactivity. These findings set the eATP-P2X7R signaling axis as an early driver of AD pathology, linking neuroinflammation to synaptic remodeling and circuit dysfunction, and suggest P2X7R inhibition as a compelling strategy to counteract AD progression.

neuroscience↗

bioRxiv2024

Systematic mapping of MCU-mediated mitochondrial calcium signaling networks

The Mitochondrial Ca2+ Uniporter Channel (MCUC) allows calcium entry into the mitochondrial matrix to regulate energy metabolism but also cell death. Although, several MCUC components have been identified, the molecular basis of mitochondrial Ca2+ signaling networks and their remodeling upon changes in uniporter activity have not been systematically assessed. Using an unbiased and quantitative proteomic approach, we map the MCUC interactome in HEK293 cells under physiological conditions and upon chronic loss or gain of mitochondrial Ca2+ uptake. Besides all previously known subunits of the uniporter, we identify 89 high-confidence interactors linking MCUC to several mitochondrial complexes and pathways, half of which are currently linked to metabolic, neurological, and immunological diseases. As a proof-of-concept, we validate EFHD1 as a binding partner of MCU, EMRE and MCUB with a MICU1-dependent inhibitory effect on Ca2+ uptake. To investigate compensatory mechanisms and functional consequences of mitochondrial Ca2+ dyshomeostasis, we systematically survey the MCU interactome upon silencing of EMRE, MCUB, MICU1 or MICU2. We observe profound changes in the MCU interconnectivity, whereby downregulation of EMRE reduces the number of MCU interactors of over 10-fold, while silencing of MCUB leads to a wider functional network linking MCU to mitochondrial stress response pathways and cell death. Altogether our study provides a comprehensive map of MCUC protein-protein interactions and a rich, high-confidence resource that can be explored to gain insights into the players and mechanisms involved in calcium signal transduction cascades and their relevance in human diseases.

cell biology↗