Biology subjects

Gardoni, F.

Publications and source records attributed to Gardoni, F..

5 recordsLinked to original sources

bioRxiv2026

Hippocampal Ring Finger Protein 10-dependent signaling supports cognitive flexibility

The ability to flexibly adapt behavior to changing environmental contingencies is a core component of brain function and relies on experience-dependent remodeling of neural circuits. While cognitive flexibility has been primarily attributed to prefrontal-striatal networks, the contribution of hippocampus and their underlying molecular substrates remains less understood. Here, we show that the dorsal hippocampus has a key role in cognitive flexibility. In particular, Ring Finger Protein 10 (RNF10)-mediated signaling, linking activation of synaptic NMDARs to specific transcriptional programs in the dorsal CA1, is necessary for cognitive flexibility. In fact, in vivo downregulation, through gene deletion and silencing of RNF10, resulting in impaired long-term synaptic plasticity, suppressed cognitive flexibility. This was reflected in the impaired ability to disengage from previously acquired contextual, visual, and spatial information and to adapt behavior to changed context. Overall, our results identified RNF10 as a key in vivo player necessary for the balance between cognitive stability and flexibility.

animal behavior and cognition↗

bioRxiv2025

Neuronal Hyperexcitability: A Key to Unravelling Hippocampal Synaptic Dysfunctions in Lafora Disease

Lafora disease (LD) is a rare progressive disorder caused by mutations in the EPM2A or EPM2B genes, characterized by the accumulation of Lafora bodies, drug-resistant epilepsy, and cognitive decline. To investigate the early molecular mechanisms of LD, we studied electrophysiological changes in the dentate gyrus (DG) of the Epm2aR240X knock-in mouse model at various ages. Electrophysiological recordings measured neuronal membrane properties, epileptic-like activity, epileptic thresholds, and synaptic plasticity in Epm2aR240X mice at 1, 3, and 12 months. We also employed PAS diastase staining, immunofluorescence, and Western blotting to detect Lafora bodies, amyloid beta deposition, and glutamate receptor subunit expression. Epileptic-like activity began at 1 month and intensified with age. Aberrant long-term potentiation (LTP) appeared at 3 months and worsened by 12 months. Notably, cannabidiol (CBD) treatment reduced excitability and restored LTP in older mice, suggesting its potential therapeutic value. These findings indicate that network hyperexcitability is an early event in LD, highlighting a therapeutic window for interventions like CBD.

neuroscience↗

bioRxiv2024

Lactate potentiates NMDA receptor currents via an intracellular redox mechanism targeting cysteines in the C-terminal domain of GluN2B subunits: implications for synaptic plasticity

SummaryThrough the Astrocyte Neuron Lactate Shuttle, astrocyte-derived lactate fuels the high-energy demands of neurons and acts as a signaling molecule, promoting synaptic plasticity and memory consolidation. Lactate regulates neuronal excitability and modulates the expression of genes related to synaptic plasticity and neuroprotection, but the molecular mode for these signaling actions is uncertain. Using patch-clamp recordings in cultured cortical neurons, we found that lactate enhances both the amplitude and the inactivation time constant of NMDA receptor currents (INMDAR) evoked by brief applications of glutamate and glycine. Not reproduced by HCAR1 agonists, this modulation depends on monocarboxylate transporters and lactate dehydrogenase, indicating the requirement for lactate entry and metabolic conversion into pyruvate and NADH formation within neurons. Disruption of intracellular calcium dynamics or inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII), a NMDAR-associated kinase linking Ca2+ signal to long-term potentiation (LTP), significantly diminishes the effects of lactate on INMDAR. We identified two redox-sensitive cysteine- containing sequences in the intrinsically disordered intracellular C-terminal domain of the GluN2B subunit that play a role in the potentiation of NMDAR by lactate. In a compelling set of experiments using HEK cells, we observed that the presence of functional CaMKII and GluN2B-containing NMDARs is necessary for the lactate-enhancing effects. Mutations in GluN2B that prevent CaMKII binding or redox regulation via cysteines abrogate the modulatory action of lactate. Immunoprecipitation experiments in neurons attest that lactate increases the association between CaMKII and GluN2B. This interaction is crucial for the potentiation of INMDAR amplitude by lactate. Proximity ligation assays between GluN2B and the postsynaptic density marker PSD-95 revealed that lactate induced an accumulation of GluN2B in dendritic spines, an effect that was prevented by a CaMKII peptide inhibitor. These results highlight a mechanistic pathway whereby lactate boosts NMDAR function through intracellular metabolic conversion and redox-sensitive interactions requiring CaMKII, establishing a link between astrocyte metabolism and synaptic modulation in neurons.

neuroscience↗

bioRxiv2021

Control of protein synthesis and memory by GluN3A-NMDA receptors through inhibition of GIT1/mTORC1 assembly

De novo protein synthesis is required for synapse modifications underlying stable memory encoding. Yet neurons are highly compartmentalized cells and how protein synthesis can be regulated at the synapse level is unknown. Here we characterize neuronal signaling complexes formed by the postsynaptic scaffold GIT1, the mTOR kinase and Raptor that couple synaptic stimuli to mTOR-dependent protein synthesis; and identify NMDA receptors containing GluN3A subunits as key negative regulators of GIT1 binding to mTOR. Disruption of GIT1/mTOR complexes by enhancing GluN3A expression or silencing GIT1 inhibits synaptic mTOR activation and restricts the mTOR-dependent translation of specific activity-regulated mRNAs. Conversely, GluN3A removal enables complex formation, potentiates mTOR-dependent protein synthesis, and facilitates the consolidation of associative and spatial memories in mice. The memory enhancement becomes evident with light or spaced training, can be achieved by selectively deleting GluN3A from excitatory neurons during adulthood, and does not compromise other aspects of cognition such as memory flexibility or extinction. Our findings provide mechanistic insight into synaptic translational control and reveal a potentially selective target for cognitive enhancement.

neuroscience↗

bioRxiv2019

CAP2 is a novel regulator of Cofilin in synaptic plasticity and Alzheimer’s disease

Cofilin is one of the major regulators of actin dynamics in spines where it is required for structural synaptic plasticity. However, our knowledge of the mechanisms controlling Cofilin activity in spines remains still fragmented. Here, we describe the cyclase-associated protein 2 (CAP2) as a novel master regulator of Cofilin localization in spines. The formation of CAP2 dimers through its Cys32 is important for CAP2 binding to Cofilin and for normal spine actin turnover. The Cys32-dependent CAP2 homodimerization and association to Cofilin are triggered by long-term potentiation (LTP) and are required for LTP-induced Cofilin translocation into spines, spine remodeling and the potentiation of synaptic transmission. This mechanism is specifically affected in the hippocampus, but not in the superior frontal gyrus, of both Alzheimers Disease (AD) patients and APP/PS1 mice, where CAP2 is down-regulated and CAP2 dimer synaptic levels are reduced. In AD hippocampi, Cofilin preferentially associates with CAP2 monomer and is aberrantly localized in spines. Taken together, these results provide novel insights into structural plasticity mechanisms that are defective in AD.

neuroscience↗