Biology subjects

Di Nardo, A. A.

Publications and source records attributed to Di Nardo, A. A..

10 recordsLinked to original sources

bioRxiv2024

Motor cortex perineuronal net modulation improves motor function in a Parkinson's disease mouse model

The 6-OHDA mouse model recapitulates midbrain dopaminergic cell loss and associated motor deficits akin to those observed in Parkinsons disease. Emerging evidence suggests that modulating interneurons in the primary motor cortex could offer a means to mitigate symptoms. In the cortex, perineuronal nets (PNNs), a specialized extracellular matrix structure generally present around fast-spiking parvalbumin interneurons, can modulate neural activity and circuit plasticity. We found that removing PNNs through unilateral or bilateral ChABC injection in the motor cortex temporarily altered motor behavior. Surprisingly, bilateral reduced motor cortex PNNs are observed two weeks after unilateral 6-OHDA midbrain lesions, whereas five weeks after lesion, PNNs return to control levels. Subsequent bilateral ChABC injections significantly improved motor function in 6-OHDA animals only when associated with motor stimulation involving enriched housing and daily motor training. Thus, PNN modulation in the motor cortex of a Parkinsons disease model enables local circuits to adapt to the loss of dopaminergic inputs, resulting in improved motor behavior.

neuroscience↗

bioRxiv2024

Non-cell autonomous OTX2 in the piriform cortex regulates parvalbumin cell maturation states and olfactory-driven behavior

The timing of critical periods of juvenile brain plasticity is driven by the maturation of parvalbumin interneurons in the neocortex, a process regulated in part by non-cell autonomous activity of the OTX2 homeoprotein transcription factor. However, the involvement of critical periods in olfactory paleocortex maturation is unknown. Here, we find that the adult mouse piriform cortex parvalbumin interneurons display particularly low molecular maturation that increases in aged animals. Expression analysis of a large panel of genes reveals that an acute increase in piriform cortex OTX2 levels in young adult mice increases Pvalb expression as well as Adamts9 expression, resulting in increased extracellular perineuronal net levels, while reducing OTX2 transfer decreases Pvalb expression and increases Mmp9 expression, resulting in decreased perineuronal net levels. Reduction in OTX2 also stimulates odor-driven cFos activity in piriform cortex parvalbumin cells and disrupts olfactory-driven behavior. Our findings suggest plasticity in piriform cortex involves OTX2 activity on parvalbumin cells and lacks strictly defined critical periods.

neuroscience↗

bioRxiv2023

Plasticity state-dependent changes in visual cortex parvalbumin interneuron mRNA translation and chromatin

The juvenile brain is shaped by critical periods (CPs) of plasticity regulated in part by parvalbumin (PV) interneurons. The "reopening" of CPs has been explored in brain disorders, yet it remains unclear whether adult enhanced plasticity recapitulates developmental mechanisms. We profiled visual cortex PV-specific ribosome-associated mRNAs at the CP peak and in two adult plasticity paradigms, chondroitinase ABC (ChABC) injection and extracellular OTX2 blockade. No shared translatomic signature emerged between the three conditions. Nonetheless, CP and ChABC-induced plasticity shared genes coding for synaptic components and extracellular matrix. Condition-specific pathways highlighted mechano-transduction and cytoskeletal remodeling for ChABC plasticity and DNA repair and heterochromatin for CP plasticity. These juvenile pathways were supported by elevated {gamma}H2AX, H3K9me3, and DAPI foci in PV cells uniquely during the CP. Thus, adult plasticity does not simply reinstate juvenile mechanisms, but instead may recruit partially overlapping, condition-specific molecular pathways revealing candidate targets for enhancing adult plasticity.

neuroscience↗

bioRxiv2021

OTX2 homeoprotein functions in adult choroid plexus

Choroid plexus secretes cerebrospinal fluid important for brain development and homeostasis. The OTX2 homeoprotein is critical for choroid plexus development and remains highly expressed in adult choroid plexus. Through RNA sequencing analyses of constitutive and conditional knockdown adult mouse models, we reveal putative roles for OTX2 in choroid plexus function, including cell signaling and adhesion, and show that it regulates the expression of factors secreted into cerebrospinal fluid, notably transthyretin. We show that Otx2 expression impacts choroid plexus immune and stress responses, and also affects splicing which leads to changes in mRNA isoforms of proteins implicated in oxidative stress response and DNA repair. Through mass spectrometry analysis of OTX2 protein partners in the choroid plexus, and in known non-cell autonomous target regions such as visual cortex and ventricular-subventricular zone, we identified putative targets involved in cell adhesion, chromatin structure and RNA processing. Thus, OTX2 retains important roles in choroid plexus function and brain homeostasis throughout life.

neuroscience↗

bioRxiv2020

Diurnal changes in perineuronal nets and parvalbumin neurons in the rat medial prefrontal cortex

Perineuronal nets (PNNs) surrounding fast-spiking, parvalbumin (PV) inhibitory interneurons are vital for providing excitatory:inhibitory balance within cortical circuits, and this balance is impaired in disorders such as schizophrenia, autism spectrum disorder, and substance use disorders. These disorders are also associated with altered diurnal rhythms, yet few studies have examined the diurnal rhythms of PNNs or PV cells. We measured the intensity and number of PV cells and PNNs labeled with Wisteria floribunda agglutinin (WFA) in the rat prelimbic medial prefrontal cortex (mPFC) at Zeitgeber times (ZT) ZT0, 6, 12, and 18. We also measured the oxidative stress marker 8-oxo-deoxyguanosine (8-oxo-dG). Relative to ZT0, the intensities of PNN and PV staining were increased in the dark (active) phase compared with the light (inactive) phase. The intensity of 8-oxo-dG was decreased from ZT0 at all time points (ZT6,12,18), in both PV cells and non-PV cells. To examine corresponding changes in inhibitory and excitatory inputs, we measured GAD 65/67 and vGlut1 puncta apposed to PV cells with and without PNNs. Relative to ZT6, there were more excitatory puncta on PV cells surrounded by PNNs at ZT18, but no changes in PV cells devoid of PNNs. No changes in inhibitory puncta were observed. Whole-cell slice recordings in fast-spiking (PV) cells with PNNs showed an increased ratio of -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor:N-methyl-D-aspartate receptor (AMPA:NMDA) at ZT18 vs. ZT6. The number of PV cells and co-labeled PV/PNN cells containing the transcription factor orthodenticle homeobox 2 (OTX2), which maintains PNNs, showed a strong trend toward an increase from ZT6 to ZT18. These diurnal fluctuations in PNNs and PV cells are expected to alter cortical excitatory:inhibitory balance and provide new insights into treatment approaches for diseases impacted by imbalances in sleep and circadian rhythms.

neuroscience↗

bioRxiv2019

Non-cell autonomous choroid plexus-derived sAPPα regulates adult hippocampus proliferation and plasticity

Elevated amyloid precursor protein (APP) expression in the choroid plexus suggests an important role for extracellular APP metabolites in cerebrospinal fluid. Despite widespread App brain expression, we hypothesized that specifically targeting choroid plexus expression could alter animal physiology. Through various genetic and viral approaches in the adult mouse, we show that choroid plexus APP levels significantly impacted proliferation in both subventricular zone and hippocampus dentate gyrus neurogenic niches. Given the role of A{beta} peptides in Alzheimer disease pathogenesis, we also tested whether favoring the production of A{beta} in choroid plexus could negatively affect niche functions. After AAV5-mediated long-term expression of human mutated APP specifically in the choroid plexus of adult wild type mice, we observe reduced niche proliferation, behavioral defects in reversal learning, and deficits in hippocampal long-term potentiation. Our findings highlight the unique role played by the choroid plexus in regulating brain function, and suggest that targeting APP in choroid plexus may provide a means to improve hippocampus function and alleviate disease-related burdens.

neuroscience↗

bioRxiv2019

Non-cell autonomous OTX2 transcription factor regulates anxiety-related behaviors in the mouse

The Otx2 homeoprotein transcription factor is expressed in the dopaminergic neurons of the ventral tegmental area, a mesencephalic nucleus involved in the control of complex behaviors through its projections to limbic structures, including the ventral hippocampus, amygdala, nucleus accumbens and medial prefrontal cortex. We find adult mice heterozygous for Otx2 show anxiolysis-like phenotype in light-dark box and elevated plus maze paradigms. However, the number of dopaminergic neurons, the integrity of their axons, their projection patterns in target structures, and the amounts of dopamine and dopamine metabolites in targets structures were not modified. Because OTX2 is expressed by the choroid plexus, secreted into cerebrospinal fluid and transferred to parvalbumin interneurons of the cortex, hippocampus, and amygdala, we investigated if this phenotype could result from the decreased synthesis of OTX2 in the choroid plexus. Indeed, the anxiolysis-like phenotype was partially recapitulated in the Otx2+/AA and scFvOtx2tg/0 choroid-plexus dependent non-cell-autonomous OTX2 loss of function mouse models. Furthermore, the phenotype was reversed by the overexpression of Otx2 specifically in choroid plexus of adult Otx2 heterozygous mice. Taken together, OTX2 synthesis by the choroid plexus followed by its secretion into the cerebrospinal fluid is an important regulator of the anxiety phenotype in the mouse.

neuroscience↗

bioRxiv2019

Regulation of perineuronal nets in the adult cortex by the electrical activity of parvalbumin interneurons

Perineuronal net (PNN) accumulation around parvalbumin-expressing (PV) inhibitory interneurons marks the closure of critical periods of high plasticity, whereas PNN removal reinstates juvenile plasticity in the adult cortex. Using targeted chemogenetic in vivo approaches in the adult mouse visual cortex, we found that transient electrical silencing of PV interneurons, directly or through inhibition of local excitatory neurons, induced PNN regression. Conversely, excitation of either neuron types did not reduce the PNN. We also observed that chemogenetically inhibited PV interneurons exhibited reduced PNN compared to their untransduced neighbors, and confirmed that single PV interneurons express multiple genes enabling cell-autonomous control of their own PNN density. Our results indicate that PNNs are dynamically regulated in the adult by PV neurons acting as sensors of their local microcircuit activities. PNN regulation provides individual PV neurons with an activity-dependent mechanism to control the local remodeling of adult cortical circuits.

neuroscience↗

bioRxiv2018

Otx2 signals from the choroid plexus to regulate adult neurogenesis

Proliferation and migration during adult neurogenesis are regulated by a microenvironment of signaling molecules originating from local vasculature, from cerebrospinal fluid produced by the choroid plexus, and from local supporting cells including astrocytes. Here, we focus on the function of OTX2 homeoprotein transcription factor in the mouse adult ventricular-subventricular zone (V-SVZ) which generates olfactory bulb neurons. We find that OTX2 secreted by choroid plexus is transferred to supporting cells of the V-SVZ and rostral migratory stream. Deletion of Otx2 in choroid plexus affects neuroblast migration and reduces the number of olfactory bulb newborn neurons. Adult neurogenesis was also decreased by expressing secreted single-chain antibodies to sequester OTX2 in the cerebrospinal fluid, demonstrating the importance of non-cell autonomous OTX2. We show that OTX2 activity modifies extracellular matrix components and signaling molecules produced by supporting astrocytes. Thus, we reveal a multi-level and non-cell autonomous role of a homeoprotein and reinforce the choroid plexus and astrocytes as key niche compartments affecting adult neurogenesis.\n\nSignificance StatementCerebrospinal fluid, local vasculature and non-neurogenic astrocytes are niche compartments that provide a microenvironment for regulating adult mouse neurogenesis. We show that OTX2 homeoprotein secreted by choroid plexus into the cerebrospinal fluid is transferred into non-neurogenic astrocytes of the ventricular-subventricular zone and rostral migratory stream where it regulates extracellular matrix and signaling factors. This non-cell-autonomous activity impacts the number of newborn neurons that integrate the olfactory bulb. Thus, we reveal a multi-level role for OTX2 and reinforce the choroid plexus as a key niche compartment affecting adult neurogenesis.

neuroscience↗

bioRxiv2017

Non-cell autonomous Otx2 homeoprotein regulates visual cortex plasticity through Gadd45b

The non-cell autonomous transfer of OTX2 homeoprotein transcription factor into juvenile mouse cerebral cortex regulates parvalbumin interneuron maturation and critical period timing. By analyzing gene expression in primary visual cortex of wild-type and Otx2+/GFP mice at plastic and non-plastic ages, we identified several putative genes implicated in Otx2-dependent visual cortex plasticity for ocular dominance. Cortical OTX2 infusion in juvenile mice induced Gadd45b/g expression through direct regulation of transcription. Intriguingly, a reverse effect was found in the adult, where reducing cortical OTX2 resulted in Gadd45b/g up-regulation. Viral expression of Gadd45b in adult visual cortex directly induced ocular dominance plasticity with concomitant changes in MeCP2 foci within parvalbumin interneurons and in methylation states of several plasticity gene promoters, suggesting epigenetic regulation. This interaction provides a molecular mechanism for OTX2 to trigger critical period plasticity yet suppress adult plasticity.

neuroscience↗