Biology subjects

Alberch, J.

Publications and source records attributed to Alberch, J..

10 recordsLinked to original sources

bioRxiv2024

A double hit affecting the IKZF1-IKZF2 tandem in immune cells of schizophrenic patients regulate specific symptoms

Schizophrenia is a complex multifactorial disorder and increasing evidence suggests the involvement of immune dysregulations in its pathogenesis. We observed that IKZF1 and IKZF2, classic immune-related transcription factors (TFs), were both downregulated in patients peripheral blood mononuclear cells (PBMCs) but not in their brain. We generated a new mutant mouse model with a reduction in Ikzf1 and Ikzf2 to study the impact of those changes. Such mice developed deficits in the three dimensions (positive-negative-cognitive) of schizophrenic-like phenotypes associated with alterations in structural synaptic plasticity. We then studied the secretomes of cultured PBMCs obtained from human patients and identified potentially secreted molecules, which depended on IKZF1 and IKZF2 levels, and that in turn have an impact on neural synchrony, structural synaptic plasticity and schizophrenic-like symptoms in in vivo and in vitro models. Our results point out that IKZF1-IKZF2-dependent immune signals negatively impact on essential neural circuits involved in schizophrenia.

neuroscience↗

bioRxiv2024

Differential contribution of direct and indirect pathways from dorsolateral and dorsomedial striatum to motor symptoms in Huntington's disease mice

The alterations in the basal ganglia circuitry associated with motor symptoms in Huntingtons Disease (HD) have been extensively investigated. Yet, the specific contribution of the direct and indirect striatal output pathways from the dorsolateral (DLS) and dorsomedial striatum (DMS) to the motor dysfunction is still not fully understood. Here, using the symptomatic R6/1 male mouse model of HD, strong functional connectivity alterations between DMS and DLS regions with the rest of brain were observed by fMRI, particularly pronounced in the DLS. Then, we systematically evaluated how the selective optogenetic stimulation of the direct and indirect pathways from DLS and DMS influences locomotion, exploratory behavior, and motor learning. In wild type (WT) mice, optogenetic stimulation of the direct pathway from DLS and the indirect pathway from DMS elicited subtle locomotor enhancements, while exploratory behavior remained unaltered. Additionally, stimulation of the indirect pathway from DLS improved the performance in the accelerated rotarod task. In contrast, in HD mice, optogenetic stimulation of the distinct striatal pathways did not modulate these behaviors. Overall, this study points to deficits in the integration of neuronal activity in HD mice, while it contributes to deeper understanding of the complexity of motor control by the diverse striatal subcircuits.

neuroscience↗

bioRxiv2023

Expansion of the neocortex and protection from neurodegeneration by in vivo transient reprogramming

Yamanaka factors (YFs) can reverse some aging features in mammalian tissues, but their effects on the brain remain largely unexplored. Here, we induced YFs in the mouse brain in a controlled spatio-temporal manner in two different scenarios: brain development, and adult stages in the context of neurodegeneration. Embryonic induction of YFs perturbed cell identity of both progenitors and neurons, but transient and low-level expression is tolerated by these cells during development. Under these conditions, YFs induction led to expanded neurogenesis, increased number of upper cortical neurons, and enhanced motor and social behavior of adult mice. Additionally, controlled YF induction is tolerated by principal neurons in the adult dorsal hippocampus and prevented the development of several hallmarks of Alzheimers disease, including cognitive decline and altered molecular signatures, in the 5xFAD mouse model. Overall, these results highlight the powerful impact of YFs on neurogenesis and their potential use in brain disorders. HighlightsO_LITransient Yamanaka factor (YF) expression during development expands neocortex C_LIO_LIYF-treated mice show enhanced cognitive skills C_LIO_LIIntermitent YF expression is tolerated by adult principal hippocampal neurons C_LIO_LILong-term intermitent YF reprogramming is protective in an AD mouse model C_LI

neuroscience↗

bioRxiv2022

Altered M2 Cortex - Superior Colliculus visual perception circuit in Huntington's Disease

The premotor cortical area -M2 cortex in rodents- connection to the striatum is involved in movement and prominently affected in Huntingtons Disease (HD). M2 cortex also projects to the superior colliculus (SC), implicated in oculomotor functions (i.e. saccades) and visual perception. Here, we investigated the contribution of M2 cortex - SC circuit to HD physiopathology in male mice. Using fMRI, we observed that M2 cortex functional connectivity with the SC was the most prominently affected circuit in the symptomatic R6/1 HD mouse model. Structural alterations were also detected by tractography and viral tracing. HD mice showed decreased defensive behavioral responses towards an unexpected visual stimuli, such as a moving robo-beetle, and decreased locomotion upon unexpected flash of light. Additionally, optogenetic M2 cortex - SC stimulation promoted avoidance responses towards the robo-beetle in WT, but not HD mice. Though, DWI measurements in vivo and ex vivo electrophysiological responses to optogenetic and electrical stimuli in the SC suggested preserved brain structure. Finally, GCamp6f fluorescence recordings with fiber photometry indicated that aberrant M2 cortex engagement might be the underlying mechanism of visual perception alterations in HD. Collectively, our findings point to a key role of M2 cortex - SC circuit alterations in HD pathophysiology.

neuroscience↗

bioRxiv2020

Hippocampal Egr1-dependent neuronal ensemblesnegatively regulate motor learning

Motor skills learning is classically associated with brain regions including cerebral and cerebellar cortices and basal ganglia. Less is known about the role of the hippocampus in the acquisition and storage of motor skills. Here we show that mice receiving a long-term training in the accelerating rotarod display marked transcriptional changes in the striatum and hippocampus when compared with short-term trained mice. We identify Egr1 as a modulator of gene expression in the hippocampus during motor learning. Using mice in which neural ensembles are permanently labeled in an Egr1 activity-dependent fashion we identify ensembles of Egr1-expressing pyramidal neurons in CA1 activated in short- and long-term trained mice in the rotarod task. When Egr1 is downregulated or these neuronal ensembles are depleted, motor learning is improved whereas their chemogenetic stimulation impairs motor learning performance. Thus, Egr1 organizes specific CA1 neuronal ensembles during the accelerating rotarod task that limit motor learning.

neuroscience↗

bioRxiv2020

In vivo progressive degeneration of Huntington's disease patient-derived neurons reveals human-specific pathological phenotypes

Research on neurodegenerative disorders has been hampered by the limited access to patients brain tissue and the absence of relevant physiological models with human neurons, accounting for the little success of clinical trials. Moreover, post-mortem samples cannot provide a detailed picture of the complex pathological mechanisms taking place throughout the course of the disease. This holds particularly true for Huntingtons disease (HD), an incurable inherited brain disorder marked by a massive striatal degeneration due to abnormal accumulation of misfolded huntingtin protein. To characterize progressive human neurodegeneration in vivo, we transplanted induced pluripotent stem cell-derived human neural progenitor cells (hNPCs) from control (CTR-hNPCs) and HD patients (HD-hNPCs) into the striatum of neonatal wild-type mice. Implanted human cells were examined by immunohistochemistry and electron microscopy, and chimeric mice were subjected to behavioral testing. Most grafted hNPCs differentiated into striatal neurons that sent axonal projections to their natural targets and established synaptic connections within the host basal ganglia circuitry. HD-hNPCs first showed developmental abnormalities characterized by an increased proliferation and accelerated medium spiny neuron (MSN) differentiation, mimicking the initial striatal hypertrophy of child mutant huntingtin (mHTT) carriers. HD human striatal neurons progressively developed mHTT oligomers and aggregates, which primarily targeted mitochondria, endoplasmic reticulum and nuclear membrane to cause structural alterations. Five months after transplantation, selective death of human MSNs and striatal degeneration altered mouse behavior, suggesting disease propagation to non-mutated host cells. Histological analysis and co-culture experiments revealed that HD-hNPCs secreted extracellular vesicles containing soluble mHTT oligomers, which were internalized by mouse striatal neurons triggering cell death. Finally, in vivo pharmacological inhibition of the exosomal secretory pathway through sphingosine-1 phosphate receptor functional antagonism, limited the spreading of apoptosis within the host striatum. Our findings cast new light on human neurodegeneration, unveiling cell and non-cell autonomous mechanisms that drive HD progression in patients.

neuroscience↗

bioRxiv2020

RTP801 Is A Key Modulator For Motor Learning

RTP801/REDD1 is a stress-regulated protein whose upregulation is necessary and sufficient to trigger neuronal death in in vitro and in vivo models of Parkinsons and Huntingtons diseases and is up regulated in compromised neurons in human postmortem brains of both neurodegenerative disorders. Indeed, in both Parkinsons and Huntingtons disease mouse models, RTP801 knockdown alleviates motor-learning deficits. Here, we investigated the physiological role of RTP801 in neuronal plasticity. RTP801 is found in rat, mouse and human synapses. The absence of RTP801 enhanced excitatory synaptic transmission in both neuronal cultures and brain slices from RTP801 knock-out (KO) mice. Indeed, RTP801 KO mice showed improved motor learning, which correlated with lower spine density but increased basal filopodia and mushroom spines in the motor cortex layer V. This paralleled with higher levels of synaptosomal GluA1 and TrkB receptors in homogenates derived from KO mice motor cortex, proteins that are associated with synaptic strengthening. Altogether, these results indicate that RTP801 has an important role modulating neuronal plasticity in motor learning.

neuroscience↗

bioRxiv2020

M2 Cortex-Dorsolateral striatum stimulation reverses motor symptoms and synaptic deficits in Huntington's Disease

Huntingtons disease (HD) is a neurological disorder characterized by motor disturbances. HD pathology is most prominent in the striatum, the central hub of basal ganglia. The cortex is the main striatal afference and progressive cortico-striatal disconnection characterizes HD. We mapped cortico-striatal dysfunction in HD mice to ultimately modulate the activity of selected cortico-striatal circuits to ameliorate motor symptoms and recover synaptic plasticity. Multimodal MRI in vivo suggested prominent functional network deficits in fronto-striatal compared to motor-striatal pathways, which were accompanied by reduced glutamate levels in the striatum of HD mice. Moreover, optogenetically-stimulated glutamate release from fronto-striatal terminals was reduced in HD mice and electrophysiological responses in striatal neurons were blunted. Remarkably, repeated M2 Cortex-dorsolateral striatum optogenetic stimulation normalized motor behavior in HD mice and evoked a sustained increase of synaptic plasticity. Overall, these results reveal that the selective stimulation of fronto-striatal pathways can become an effective therapeutic strategy in HD.

neuroscience↗

bioRxiv2020

SYNAPTIC RTP801 CONTRIBUTES TO MOTOR LEARNING DYSFUNCTION IN HUNTINGTON DISEASE

RTP801/REDD1 is a stress responsive protein that mediates mutant huntingtin (mhtt) toxicity in cellular models and is up regulated in Huntingtons disease (HD) patients putamen. Here, we investigated whether RTP801 is involved in motor impairment in HD by affecting striatal synaptic plasticity. Ectopic mhtt was over expressed in cultured rat primary neurons. The protein levels of RTP801 were assessed in homogenates and crude synaptic fractions from human postmortem HD brains and mouse models of HD. Striatal RTP801 expression was knocked down with adeno-associated viral particles containing a shRNA in the R6/1 mouse model of HD and motor learning was then tested. Ectopic mhtt elevated RTP801 in synapses of cultured neurons. RTP801 was also up regulated in striatal synapses from HD patients and mouse models. Knocking down RTP801 in the R6/1 mouse striatum prevented motor learning impairment. RTP801 silencing normalized the Ser473 Akt hyperphosphorylation by downregulating Rictor and it induced synaptic elevation of calcium permeable GluA1 subunit and TrkB receptor levels, suggesting an enhancement in synaptic plasticity. These results indicate that mhtt-induced RTP801 mediates motor dysfunction in a HD murine model, revealing a potential role in the human disease. These findings open a new therapeutic framework focused on the RTP801/Akt/mTOR axis.

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bioRxiv2019

Modulation of dopamine D1 receptors via histamine H3 receptors is a novel therapeutic target for Huntington’s disease

Early Huntingtons disease (HD) include over-activation of dopamine D1 receptors (D1R), producing an imbalance in dopaminergic neurotransmission and cell death. To reduce D1R over-activation, we present a strategy based on targeting complexes of D1R and histamine H3 receptors (H3R). Using an HD striatal cell model and HD organotypic brain slices we found that D1R-induced cell death signaling and neuronal degeneration, are mitigated by an H3R antagonist. We demonstrate that the D1R-H3R heteromer is expressed in HD animal models at early but not late stages of HD, correlating with HD progression. In accordance, we found this target expressed in human control subjects and low-grade HD patients. Finally, treatment of HD mice with an H3R antagonist prevented cognitive and motor learning deficits, as well as the loss of heteromer expression. Taken together, our results indicate that D1R - H3R heteromers play a pivotal role in dopamine signaling and represent novel targets for treating HD.\n\nImpact StatementProgression of Huntingtons disease can be slowed by altering dopamine signalling through the Dopamine 1 receptor - Histamine 3 receptor heteromer.

neuroscience↗