Biology subjects

Pizzo, P.

Publications and source records attributed to Pizzo, P..

5 recordsLinked to original sources

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↗

bioRxiv2025

Lipid droplet dysmetabolism affects cell homeostasis in an in vitro model of Alzheimer disease

Lipid droplets (LD) are dynamic organelles involved in neutral lipid storage, energy homeostasis, and can prevent lipotoxicity and oxidative distress. LD dysmetabolism has been considered a pathological hallmark in neurodegenerative disorders, including Alzheimers disease (AD). In this study, we investigated the alterations in LD metabolism and their impact on mitochondria-associated membranes (MAM) in an in vitro model of AD, namely the mouse neuroblastoma cell (N2A) line overexpressing the amyloid precursor protein with the familial Swedish mutation (APPswe). In APPswe cells, we found depletion of LD associated with an accumulation of free fatty acids that can be related with the observed LD degradation by chaperone-mediated autophagy. In these cells we also found decreased levels of seipin, which might contribute to triacylglycerol accumulation. These lipid alterations are associated with increased levels of ROS and lipid peroxidation in APPswe cells. The pharmacological modulation of DGAT1, that mediates triacylglycerol synthesis, normalized LD size and improved ER-mitochondria contacts and mitochondrial function in APPswe cells. In summary, these observations suggest the involvement of altered LD metabolism in AD pathophysiology, which impact on MAM and mitochondria function leading to cell dyshomeostasis. Our findings also support the idea that LD are relevant therapeutic targets in AD. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=111 SRC="FIGDIR/small/658644v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@de3fc6org.highwire.dtl.DTLVardef@12d1f2forg.highwire.dtl.DTLVardef@15a5185org.highwire.dtl.DTLVardef@9e1655_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2025

Integrating simulated and experimental data to identify mitochondrial bioenergetic defects in Parkinson's Disease models

Mitochondrial bioenergetics are vital for ATP production and are associated with several diseases, including Parkinsons Disease. Here, we simulated a computational model of mitochondrial ATP production to interrogate mitochondrial bioenergetics under physiological and pathophysiological conditions, and provide a data resource that can be used to interpret mitochondrial bioenergetics experiments. We first characterised the impact of several common respiratory chain impairments on experimentally-observable bioenergetic parameters. We then established an analysis pipeline to integrate simulations with experimental data and predict the molecular defects underlying experimental bioenergetic phenotypes. We applied the pipeline to data from Parkinsons Disease models. We verified that the impaired bioenergetic profile previously measured in Parkin knockout neurons can be explained by increased mitochondrial uncoupling. We then generated primary cortical neurons from a Pink1 KO mouse model of Parkinsons, and measured reduced OCR capacity and increased resistance to Complex III inhibition. Here, our pipeline predicted that multiple respiratory chain impairments are required to explain this bioenergetic phenotype. Finally, we provide all simulated data as a user-friendly resource that can be used to interpret mitochondrial bioenergetics experiments, predict underlying molecular defects, and inform experimental design. HighlightsO_LIThe complexity of mitochondrial bioenergetics can make experimental data difficult to interpret. C_LIO_LIWe simulated a computational model of mitochondrial bioenergetics in healthy and pathological conditions, and established an analysis pipeline to integrate model simulations with experimental data. C_LIO_LIWe applied the pipeline to data from Parkinsons Disease models to predict the molecular defects underlying Parkinsons-related pathology. C_LIO_LIWe provide all outputs in a user-friendly Excel file, which serves as a valuable resource to the community for insight into the effects of pathology on mitochondrial bioenergetics and for interpretation of experimental results. C_LI

neuroscience↗

bioRxiv2023

Simultaneous detection of membrane contact dynamics and associated Ca2+ signals by reversible chemogenetic reporters

Membrane contact sites (MCSs) are hubs allowing various cell organelles to coordinate their activities. The dynamic nature of these sites and their small size hinder analysis by current imaging techniques. To overcome these limitations, we here designed a series of reversible chemogenetic reporters incorporating improved, low-affinity variants of splitFAST, and studied the dynamics of different MCSs at high spatiotemporal resolution, both in vitro and in vivo. We demonstrated that these versatile reporters suit different experimental setups well, allowing one to address challenging biological questions. Using these novel probes, we identified a hitherto unknown pathway, in which calcium (Ca2+) signalling dynamically regulates endoplasmic reticulum-mitochondria juxtaposition, characterizing the underlying mechanism. Finally, by integrating Ca2+-sensing capabilities into the splitFAST technology, we introduced PRINCESS (PRobe for INterorganelle Ca2+-Exchange Sites based on SplitFAST), an unprecedented class of reporters to simultaneously detect MCSs and measure the associated Ca2+ dynamics using a single biosensor.

cell biology↗

bioRxiv2019

Hexokinase 2 displacement from mitochondria-associated membranes prompts Ca2+-dependent death of cancer cells

Cancer cells undergo changes in metabolic and survival pathways that increase their malignancy. Isoform 2 of the glycolytic enzyme hexokinase (HK2) enhances both glucose metabolism and resistance to death stimuli in many neoplastic cell types. Here we observe that HK2 locates at mitochondria-endoplasmic reticulum (ER) contact sites called MAMs (Mitochondria-Associated Membranes). HK2 displacement from MAMs with a selective peptide triggers mitochondrial Ca2+ overload caused by Ca2+ release from ER via inositol-3-phosphate receptors (IP3Rs) and by Ca2+ entry through plasma membrane. This results in Ca2+-dependent calpain activation, mitochondrial depolarization and cell death. The HK2-targeting peptide causes massive death of chronic lymphocytic leukemia B cells freshly isolated from patients, and an actionable form of the peptide reduces growth of breast and colon cancer cells allografted in mice without noxious effects on healthy tissues. These results identify a signalling pathway primed by HK2 displacement from MAMs that can be activated as anti-neoplastic strategy.

cancer biology↗