Cortical Neurons Research Articles

Short Peptides Protect Fibroblast-Derived Induced Neurons from Age-Related Changes.

Neurons become more vulnerable to stress factors with age, which leads to increased oxidative DNA damage, decreased activity of mitochondria and lysosomes, increased levels of p16, decreased LaminB1 proteins, and the depletion of the dendritic tree. These changes are exacerbated in vulnerable neuronal populations during the development of neurodegenerative diseases. Glu-Asp-Arg (EDR) and Lys-Glu-Asp (KED), and Ala-Glu-Asp-Gly (AEDG) peptides have previously demonstrated neuroprotective effects in various models of Alzheimer's disease. In this study, we investigated the influence of EDR, KED, and AEDG peptides on the aging of fibroblast-derived induced neurons. We used a new in vitro cellular model of human neuronal aging based on the transdifferentiation of aged dermal fibroblasts from elderly donors into induced cortical neurons. All peptides promote the arborization of the dendritic tree, increasing both the number of primary processes and the total length of dendrites. Tripeptides have no effect on the activity of mitochondria and lysosomes and the level of p16 protein in induced neurons. EDR peptide reduces oxidative DNA damage in induced neurons derived from elderly donor fibroblasts. Short peptides partially protect induced neurons from age-related changes and stimulate dendritogenesis in neurons. They can be recommended for use as neuroprotective agents.

Effect of fatigue on intermuscular EMG-EMG coupling during bench press exercise at 60% 1RM workload in males.

To explore the neuromuscular control mechanism and quantifying the fatigue response during bench press exercise is important references to prescribe an appropriate exercise program. However, current literature struggles to provide a concrete conclusion on the changes of intermuscular EMG-EMG coupling between synergistic and antagonist muscles during the exercise. Thus, the current study was designed to reveal fatigue-related changes of intermuscular EMG-EMG coupling during bench press exercise. Thirty-one healthy male participants performed a bench press exercise on the Smith machine at 60% One Repetition Maximum (1RM) workload to exhaustion, while surface electromyographic signals (sEMG) were collected from triceps brachii (TB), biceps brachii (BB), anterior deltoid (AD), posterior deltoid (PD), and pectoralis major (PM). Surface EMG signals were divided into the first half and second half of the bench press exercise. Phase synchronization index (PSI) was calculated between sEMG of synergistic muscle pairs AD-TB, AD-PM and antagonist muscle pairs BB-TB, AD-PD. EMG power of TB, AD, PD, PM muscles in alpha (8-12 Hz) frequency band and EMG power of each muscle in beta (15-35 Hz), and gamma (35-60 Hz) frequency bands were all increased during the second half of contraction compared with the first half of contraction. PSI of gamma frequency band was significantly decreased in BB-TB muscle pair while EMG-EMG coupling of AD-TB in gamma frequency band was significantly increased during the second half of contraction compared to the first half of contraction. The results indicated a decrease of interconnection between synchronized cortical neurons and the motoneuron pool of BB and TB, and an increase of interconnection between AD-TB muscles during fatiguing bench press exercise at 60% 1RM workload. The changes of intermuscular coupling may be related to the supraspinal modulations to compensate for the decrease of muscle force as well as a result of unbalanced changes of agonist and antagonist muscle contractility.

Validation of a functional human AD model with four AD therapeutics utilizing patterned ipsc-derived cortical neurons integrated with microelectrode arrays

Preclinical methods are needed for screening potential Alzheimer’s disease (AD) therapeutics that recapitulate phenotypes found in the Mild Cognitive Impairment (MCI) stage or even before this stage of the disease. This would require a phenotypic system that reproduces cognitive deficits without significant neuronal cell death to mimic the clinical manifestations of AD during these stages. Long-term potentiation (LTP), which is a correlate of learning and memory, was induced in mature human iPSC-derived cortical neurons cultured on microelectrode arrays utilizing circuit patterns connecting two adjacent electrodes. We demonstrated an LTP system that modeled the MCI and pre-MCI stages of Alzheimer’s and validated this functional system utilizing four AD therapeutics, which was also verified utilizing patch-clamp electrophysiology. LTP was induced by tetanic electrical stimulation, and LTP maintenance was significantly reduced in the presence of Amyloid-Beta 42 (Aβ42) oligomers compared to the controls, however, co-treatment with AD therapeutics (Donepezil, Memantine, Rolipram and Saracatinib) corrected Aβ42-induced LTP impairment. The results illustrate the utility of the system as a validated platform to model MCI AD pathology, and potentially for the pre-MCI phase before significant neuronal death. This system also has the potential to become an ideal platform for high-content therapeutic screening for other neurodegenerative diseases.

Nanomagnetic Guidance Shapes the Structure-Function Relationship of Developing Cortical Networks.

In this study, we implement large-scale nanomagnetic guidance on cortical neurons to guide dissociated neuronal networks during development. Cortical networks cultured over microelectrode arrays were exposed to functionalized magnetic nanoparticles, followed by magnetic field exposure to guide neurites over 14 days in vitro. Immunofluorescence of the axonal protein Tau revealed a greater number of neurites that were longer and aligned with the nanomagnetic force relative to nonguided networks. This was further confirmed through brightfield imaging on the microelectrode arrays during development. Spontaneous electrophysiological recordings revealed that the guided networks exhibited increased firing rates and frequency in force-aligned connectivity identified through Granger Causality. Applying this methodology across networks with nonuniform force directions increased local activity in target regions, identified as regions in the direction of the nanomagnetic force. Altogether, these results demonstrate that nanomagnetic forces guide the structure and function of dissociated cortical neuron networks at the millimeter scale.

Bilateral Alignment of Receptive Fields in the Olfactory Cortex.

Each olfactory cortical hemisphere receives ipsilateral odor information directly from the olfactory bulb and contralateral information indirectly from the other cortical hemisphere. Since neural projections to the olfactory cortex are disordered and non-topographic, spatial information cannot be used to align projections from the two sides like in the visual cortex. Therefore, how bilateral information is integrated in individual cortical neurons is unknown. We have found, in mice, that the odor responses of individual neurons to selective stimulation of each of the two nostrils are significantly correlated, such that odor identity decoding optimized with information arriving from one nostril transfers very well to the other side. Nevertheless, these aligned responses are asymmetric enough to allow decoding of stimulus laterality. Computational analysis shows that such matched odor tuning is incompatible with purely random connections but is explained readily by Hebbian plasticity structuring bilateral connectivity. Our data reveal that despite the distributed and fragmented sensory representation in the olfactory cortex, odor information across the two hemispheres is highly coordinated.Significance statement Like other sense organs, animals typically have two nostrils, but how odor information from the two sides is combined to build bilateral olfactory representations remains largely unknown. Grimaud et al. find that the responses of neurons in the olfactory cortex in awake mice to odors presented separately to the ipsilateral or contralateral nostril are significantly correlated, beyond chance. Such aligned responses could arise from Hebbian plasticity in interhemispheric connections that relies on common odor experiences across the two nostrils. While responses are correlated, the remaining asymmetries in responses to the two nostrils allowed decoding of stimulus laterality. This study points to unexpected order in an olfactory circuit and prompts future work on how olfactory experience can shape interhemispheric information integration.

Yigong San improves learning and memory functions of APP/PS1 transgenic mice by regulating brain fluid metabolism

To explore the mechanism by which Yigong San (YGS) improves learning and memory abilities of APP/PS1 transgenic mice in light of cerebral fluid metabolism regulation. Three-month-old male APP/PS1 transgenic mice and wild-type C57BL/6 mice were both randomized into control group, model group, donepezil (1.67 mg/kg) group, and YGS (7.5 g/kg) group and received the corresponding treatments via gavage once daily for one month. After the treatments, the mice were assessed for learning and memory functions using Morris water maze test and examined for hippocampal and cortical pathologies and amyloid plaques using HE, immunohistochemical and thioflavin S staining; ELISA and Evans blue method were used for detecting Aβ1-40 and Aβ1-42 levels in the brain tissue and serum and assessing blood-brain barrier (BBB) integrity. Immunofluorescence colocalization was used to investigate AQP4 polarization on astrocytes. Western blotting was performed to detect the expressions of VE-cadherin, ZO-1, occludin, β-amyloid precursor protein (APP), BACE1, insulin-degrading enzyme (IDE), LRP1, RAGE, and AQP4 proteins. Compared with the control mice, APP/PS1 mice showed significant impairment of learning and memory abilities, increased degeneration or necrosis of hippocampal and cortical neurons, pathological scores, Aβ-positive plaques, elevated Aβ1-40 and Aβ1-42 levels in the brain tissue and serum, increased BBB permeability, upregulated RAGE expression, lowered expressions of VE-cadherin, LRP1, ZO-1, occludin, and AQP4 proteins, and reduced AQP4- expressing GFAP-positive cells. YGS treatment significantly improved the performance of the transgenic mice in Morris water maze test, reduced hippocampal and cortical pathologies and Aβ-positive plaques, and ameliorated the abnormal changes in Aβ1-40 and Aβ1-42 levels, BBB permeability, protein expressions of RAGE, VE-cadherin, LRP1, ZO-1, occludin and AQP4, and the number of AQP4-expressing GFAP-positive cells. YGS improves learning and memory changes in APP/PS1 mice by ameliorating neuronal damage and Aβ pathology in the brain and regulating brain fluid metabolism.

RNA Binding Protein Dysfunction Links Smoldering/Slowly Expanding Lesions to Neurodegeneration in Multiple Sclerosis.

Despite the advances in treatments for multiple sclerosis (MS), unremitting neurodegeneration continues to drive disability and disease progression. Smoldering/slowly expanding lesions (SELs) and dysfunction of the RNA binding protein (RBP) heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) are pathologic hallmarks of MS cortex and intricately tied to disability and neurodegeneration, respectively. We hypothesized that neuronal hnRNP A1 dysfunction contributes to neurodegeneration and is exacerbated by smoldering/SELs in progressive MS. Neuronal hnRNP A1 pathology (nucleocytoplasmic mislocalization of hnRNP A1) was examined in healthy control and MS brains using immunohistochemistry. MS cases were stratified by severity of hnRNP A1 pathology to examine the link between RBP dysfunction, demyelination, and neurodegeneration. We found that smoldering/SELs were only present within a subset of MS tissues characterized by elevated neuronal hnRNP A1 pathology (MS-A1high) in adjacent cortical gray matter. In contrast to healthy controls and MS with low hnRNP A1 pathology (MS-A1low), MS-A1high showed elevated markers of neurodegeneration, including neuronal loss and injury, brain atrophy, axonal loss, and axon degeneration. Additionally, we discovered a subpopulation of morphologically intact neurons lacking expression of NeuN, a neuron-specific RBP, in cortical projection neurons in MS-A1high cases. hnRNP A1 dysfunction contributes to neurodegeneration and may be exacerbated by smoldering/SELs in progressive MS. The discovery of NeuN-negative neurons suggests that some cortical neurons may only be injured and not lost. By characterizing RBP pathology in MS cortex, this study has important implications for understanding the pathogenic mechanisms driving neurodegeneration, the substrate of disability and disease progression. ANN NEUROL 2024.

A vector system encoding histone H3 mutants facilitates manipulations of the neuronal epigenome

The differentiation of developmental cell lineages is associated with genome-wide modifications in histone H3 methylation. However, the causal role of histone H3 methylation in transcriptional regulation and cell differentiation has been difficult to test in mammals. The experimental overexpression of histone H3 mutants carrying lysine-to-methionine (K-to-M) substitutions has emerged as an alternative tool for inhibiting the endogenous levels of histone H3 methylation at specific lysine residues. Here, we leverage the use of histone K-to-M mutants by creating Enhanced Episomal Vectors that enable the simultaneous depletion of multiple levels of histone H3 lysine 4 (H3K4) or lysine 9 (H3K9) methylation in projection neurons of the mouse cerebral cortex. Our approach also facilitates the simultaneous depletion of H3K9 and H3K27 trimethylation (H3K9me3 and H3K27me3, respectively) in cortical neurons. In addition, we report a tamoxifen-inducible Cre-FLEX system that allows the activation of mutant histones at specific developmental time points or in the adult cortex, leading to the depletion of specific histone marks. The tools presented here can be implemented in other experimental systems, such as human in vitro models, to test the combinatorial role of histone methylations in developmental fate decisions and the maintenance of cell identity.

Corticostriatal Maldevelopment in the R6/2 Mouse Model of Juvenile Huntington's Disease.

There is a growing consensus that brain development in Huntington's disease (HD) is abnormal, leading to the idea that HD is not only a neurodegenerative but also a neurodevelopmental disorder. Indeed, structural and functional abnormalities have been observed during brain development in both humans and animal models of HD. However, a concurrent study of cortical and striatal development in a genetic model of HD is still lacking. Here we report significant alterations of corticostriatal development in the R6/2 mouse model of juvenile HD. We examined wildtype (WT) and R6/2 mice at postnatal (P) days 7, 14, and 21. Morphological examination demonstrated early structural and cellular alterations reminiscent of malformations of cortical development, and ex vivo electrophysiological recordings of cortical pyramidal neurons (CPNs) demonstrated significant age- and genotype-dependent changes of intrinsic membrane and synaptic properties. In general, R6/2 CPNs had reduced cell membrane capacitance and increased input resistance (P7 and P14), along with reduced frequency of spontaneous excitatory and inhibitory synaptic events during early development (P7), suggesting delayed cortical maturation. This was confirmed by increased occurrence of GABA A receptor-mediated giant depolarizing potentials at P7. At P14, the rheobase of CPNs was significantly reduced, along with increased excitability. Altered membrane and synaptic properties of R6/2 CPNs recovered progressively, and by P21 they were similar to WT CPNs. In striatal medium-sized spiny neurons (MSNs), a different picture emerged. Intrinsic membrane properties were relatively normal throughout development, except for a transient increase in membrane capacitance at P14. The first alterations in MSNs synaptic activity were observed at P14 and consisted of significant deficits in GABAergic inputs, however, these also were normalized by P21. In contrast, excitatory inputs began to decrease at this age. We conclude that the developing HD brain is capable of compensating for early developmental abnormalities and that cortical alterations precede and are a main contributor of striatal changes. Addressing cortical maldevelopment could help prevent or delay disease manifestations.

Glutamate signaling and neuroligin/neurexin adhesion play opposing roles that are mediated by major histocompatibility complex I molecules in cortical synapse formation.

Although neurons release neurotransmitter before contact, the role for this release in synapse formation remains unclear. Cortical synapses do not require synaptic vesicle release for formation (Verhage et al., 2000; Sando et al., 2017; Sigler et al., 2017; Held et al., 2020), yet glutamate clearly regulates glutamate receptor trafficking (Roche et al., 2001; Nong et al., 2004) and induces spine formation (Engert and Bonhoeffer, 1999; Maletic-Savatic et al., 1999; Toni et al., 1999; Kwon and Sabatini, 2011; Oh et al., 2016). Using rat and murine culture systems to dissect molecular mechanisms, we found that glutamate rapidly decreases synapse density specifically in young cortical neurons in a local and calcium-dependent manner through decreasing N-methyl-D-aspartate receptor (NMDAR) transport and surface expression as well as co-transport with neuroligin (NL1). Adhesion between NL1 and neurexin 1 protects against this glutamate-induced synapse loss. Major histocompatibility I (MHCI) molecules are required for the effects of glutamate in causing synapse loss through negatively regulating NL1 levels in both sexes. Thus, like acetylcholine at the neuromuscular junction (NMJ), glutamate acts as a dispersal signal for NMDARs and causes rapid synapse loss unless opposed by NL1-mediated trans-synaptic adhesion. Together, glutamate, MHCI and NL1 mediate a novel form of homeostatic plasticity in young neurons that induces rapid changes in NMDARs to regulate when and where nascent glutamatergic synapses are formed.Significance Statement The role for neurotransmitter release in synaptogenesis in the central nervous system (CNS) remains unclear. Here, we reconcile conflicting results in the field by showing that glutamate plays an important role in synapse formation by acting as a dispersal signal for NMDARs that is counteracted by trans-synaptic adhesion in intact tissue, similar to the role for neurotransmitter at the NMJ. We also describe a novel form of homeostatic plasticity in young neurons that allows them to respond to changes in activity through surprisingly rapid changes in synapse density. Finally, we show that this plasticity is modulated by immune proteins-MHCI molecules-through negative regulation of NL1 levels, connecting two important synaptic signaling pathways for the first time.

Early divergent modulation of NLRP2′s and NLRP3′s inflammasome sensors vs. AIM2′s one by signals from Aβ·Calcium-sensing receptor complexes in human astrocytes

Alzheimer’s disease (AD), the most prevalent human dementia, is driven by accruals of extracellular Aβ42 senile patches and intracellular neurofibrillary tangles of hyperphosphorylated Tau (p-Tau) proteins. AD’s concurrent neuroinflammation is prompted by innate immunity-related cytosolic protein oligomers named inflammasomes. Upon proper “first” (priming) and “second” (activating) signals, inflammasomes overproduce proinflammatory Interleukin (IL)-1β, and IL-18 while cleaving pyroptosis-promoting Gasdermin D’s N-terminal fragments. Our earlier studies highlighted that in pure monocultures, exogenous Aβ25-35-treated nonproliferating human cortical astrocytes (HCAs) made and released surpluses of endogenous Aβ42-oligomers (−os) and p-Tau-os, just as alike-treated human cortical neurons did. Aβ25-35-exposed HCAs also over-released NO, VEGFA, and IL-6. Aβ•CaSR (Aβ·Calcium-Sensing Receptor) complexes generated intracellular signals mediating all such neurotoxic effects since CaSR’s negative allosteric modulators (aka NAMs or calcilytics, e.g., NPS2143) fully suppressed them. However, it had hitherto remained unexplored whether signals from Aβ·CaSR complexes also induced the early expression and/or activation of NOD-like 2 (NLRP2) and 3 (NLRP3) and of PYHIN absent in melanoma 2 (AIM2) inflammasomes in monocultured HCAs. To clarify this topic, we used in-situ-Proximity Ligation, qRT-PCR, double antibody arrays, immunoblots, and Caspase 1/4 enzymatic assays. Aβ·CaSR complexes quickly assembled on HCAs surface and issued intracellular signals activating Akt and JAK/STAT axes. In turn, the latter upregulated NLRP2 and NLRP3 PRRs (pattern recognition receptors) yet downregulated AIM2. These effects were specific, being significantly hindered by NPS2143 and inhibitors of PI3K (LY294002), AMPKα (Dorsomorphin), mTOR (Torin1), and JAK/TYK (Brepoticinib). A wide-spectrum inhibitor, Bay11-7082, intensified the Aβ·CaSR/Akt/JAK/STAT axis-driven opposite control of NLRP3’s and AIM2’s PRR proteins without affecting NLRP2 PRR upregulation. However, the said effects on the PRRs proteins vanished within 24-h. Moreover, Aβ·CaSR signals neither concurrently changed ASC, pro-IL-1β, and Gasdermin-D (holo- and fragments) protein levels and Caspases 1 and 4 enzymatic activities nor induced pyroptosis. Therefore, Aβ·CaSR cues acted as “first (priming) signals” temporarily increasing NLRP2 and NLRP3 PRRs expression without activating the corresponding inflammasomes. The neatly divergent modulation of NLRP3’s vs. AIM2’s PRR proteins by Aβ·CaSR cues and by Bay11-7082 suggests that, when bacterial or viral DNA fragments are absent, AIM2 might play “anti-inflammasomal” or other roles in HCAs. However, Bay11-7082’s no effect on NLRP2 PRR overexpression also reveals that CaSR’s downstream mechanisms controlling inflammasomes’ sensors are quite complex in HCAs, and hence, given AD’s impact on human health, well worth further studies.

Optogenetic stimulation recruits cortical neurons in a morphology-dependent manner.

Single-photon optogenetics enables precise, cell-type-specific modulation of neuronal circuits, making it a crucial tool in neuroscience. Its miniaturization in the form of fully implantable wide-field stimulator arrays enables long-term interrogation of cortical circuits and bares promise for Brain-Machine Interfaces for sensory and motor function restoration. However, achieving selective activation of functional cortical representations poses a challenge, as studies show that targeted optogenetic stimulation results in activity spread beyond one functional domain. While recurrent network mechanisms contribute to activity spread, here we demonstrate with detailed simulations of isolated pyramidal neurons from cat of unknown sex that already neuron morphology causes a complex spread of optogenetic activity at the scale of one cortical column. Since the shape of a neuron impacts its optogenetic response, we find that a single stimulator at the cortical surface recruits a complex spatial distribution of neurons that can be inhomogeneous and vary with stimulation intensity and neuronal morphology across layers. We explore strategies to enhance stimulation precision, finding that optimizing stimulator optics may offer more significant improvements than preferentially somatic expression of the opsin through genetic targeting. Our results indicate that, with the right optical setup, single-photon optogenetics can precisely activate isolated neurons at the scale of functional cortical domains spanning several hundred micrometers.Significance Statement Sensory features, such as the position or orientation of a visual stimulus, are mapped onto the surface of cortex as functional domains. Their selective activation, that may enable eliciting complex percepts, is intensively pursued for basic science and clinical applications. However, delivery of light into one functional domain in optogenetically transfected cortex results in complex, widespread neuronal activity, spreading beyond the targeted domain. Our computational study reveals that neuron morphology contributes to this diffuse response in a cortical-layer and intensity-dependent manner. We show that enhancing the stimulator optics is more effective than soma-targeting of the opsin in increasing spatial precision of stimulation. Our simulations provide insights for designing optogenetic stimulation protocols and hardware to achieve selective activation of functional domains.

Cortical, striatal, and thalamic populations self-organize into a functionally connected circuit with long-term memory properties

The human brain is a complex organ with an intricate neuronal connectivity and diverse functional regions. Neurological disorders often disrupt the delicate balance among these anatomical compartments, resulting in severe impairments. The available therapeutic options constitute an incomplete solution as many patients respond partially, highlighting the need for continued research into causes and treatments. Bottom-up approaches, like in vitro models, offer insights into brain functions as they recreate the in vivo microenvironment that allows studying how specific features affect physiological and pathological conditions. In this work, we engineered the cortical-striatal-thalamic (CST) circuit, involved in many brain functions such as action initiation and selection, using a three-compartment polymeric device. We characterized the emerging spontaneous electrophysiological activity by using Micro-Electrode Arrays (MEAs). Cortical neurons exhibited complex bursting activity, which influenced the entire circuit. Striatal and thalamic neurons displayed predominantly tonic firing when isolated, while interconnections with the cortex synchronized and organized their neuronal activity, highlighting the cortical pivotal role in bursting activity and information processing. The CST circuit demonstrated self-organization abilities and displayed high entropy values, indicative of dynamic richness and information encoding potential. Furthermore, we proved the CST’s involvement in learning and memory. Our CST model provides a platform for further exploration into brain circuitry and potential therapeutic interventions, underscoring the necessity of realistic in vitro models to fully understand neurological diseases' pathophysiology.

Apoptosis is increased in cortical neurons of female Marfan Syndrome mice.

The study revealed that female mice with a FBN1 C1041G/+ mutation have more apoptotic neurons in sensory and motor cortical brain tissue compared to wildtype litter mates.

Synchrony dynamics underlie irregular neocortical spiking.

Cortical neurons are characterized by their variable spiking patterns. We challenge prevalent theories for the origin of spiking variability. We examine the specific hypothesis that cortical synchrony drives spiking variability in vivo . Using dynamic clamp, we demonstrate that intrinsic neuronal properties do not contribute substantially to spiking variability, but rather spiking variability emerges from weakly synchronous network drive. With large-scale electrophysiology we quantify the degree of synchrony and its time scale in cortical networks in vivo . We demonstrate that physiological levels of synchrony are sufficient to generate irregular responses found in vivo . Further, this synchrony shifts over timescales ranging from 25 to 200 ms, depending on the presence of external sensory input. Such shifts occur when the network moves from spontaneous to driven modes, leading naturally to a decline in response variability as observed across cortical areas. Finally, while individual neurons exhibit reliable responses to physiological drive, different neurons respond in a distinct fashion according to their intrinsic properties, contributing to stable synchrony across the neural network.

Altered tubulin detyrosination due to SVBP malfunction induces cytokinesis failure and senescence, underlying a complex hereditary spastic paraplegia.

Senescence, marked by permanent cell cycle arrest may contribute to the decline in regenerative potential and neuronal function, thereby promoting neurodegenerative disorders. In this study, we employed whole exome sequencing to identify a previously unreported biallelic missense variant in SVBP (p.Leu49Pro) in six patients from three unrelated families. These affected individuals present with a complex hereditary spastic paraplegia (HSP), peripheral neuropathy, verbal apraxia, and intellectual disability, exhibiting a milder phenotype compared to patients with nonsense SVBP mutations described previously. Consistent with SVBP's primary role as a chaperone necessary for VASH-mediated tubulin detyrosination, both patient fibroblasts with the p.Leu49Pro mutation, and HeLa cells harboring an SVBP knockdown exhibit microtubule dynamic instability and alterations in pericentriolar material (PCM) component trafficking and centrosome cohesion. In patient fibroblasts, structural abnormalities in the centrosome trigger mitotic errors and cellular senescence. Notably, premature senescence characterized by elevated levels of p16INK4, was also observed in patient peripheral blood mononuclear cells (PBMCs). Taken together, our findings underscore the critical role of SVBP in the development and maintenance of the central nervous system, providing novel insights associating cytokinesis failure with cortical motor neuron disease and intellectual disability.

Mapping the epigenomic landscape of post-traumatic stress disorder in human cortical neurons.

The study conducted a comprehensive genome-wide analysis of differential 5mC and 5hmC modifications at both CpG and non-CpG sites in postmortem orbitofrontal neurons from 25 PTSD cases and 13 healthy controls. It was observed that PTSD patients exhibit a greater number of differential 5hmC sites compared to 5mC sites. Specifically, individuals with PTSD tend to show hyper-5mC/5hmC at CpG sites, particularly within CpG islands and promoter regions, and hypo-5mC/5hmC at non-CpG sites, especially within intragenic regions. Functional enrichment analysis indicated distinct yet interconnected roles for 5mC and 5hmC in PTSD. The 5mC marks primarily regulate cell-cell adhesion processes, whereas 5hmC marks are involved in embryonic morphogenesis and cell fate commitment. By integrating published PTSD findings from central and peripheral tissues through multi-omics approaches, several biological mechanisms were prioritized, including developmental processes, HPA axis regulation, and immune responses. Based on the consistent enrichment in developmental processes, we hypothesize that if epigenetic changes occur during early developmental stages, they may increase the risk of developing PTSD following trauma exposure. Conversely, if these epigenetic changes occur in adulthood, they may influence neuronal apoptosis and survival mechanisms.

Loss of PHF6 causes spontaneous seizures, enlarged brain ventricles and altered transcription in the cortex of a mouse model of the Börjeson-Forssman-Lehmann intellectual disability syndrome.

Börjeson-Forssman-Lehmann syndrome (BFLS) is an X-linked intellectual disability and endocrine disorder caused by pathogenic variants of plant homeodomain finger gene 6 (PHF6). An understanding of the role of PHF6 in vivo in the development of the mammalian nervous system is required to advance our knowledge of how PHF6 mutations cause BFLS. Here, we show that PHF6 protein levels are greatly reduced in cells derived from a subset of patients with BFLS. We report the phenotypic, anatomical, cellular and molecular characterization of the brain in males and females in two mouse models of BFLS, namely loss of Phf6 in the germline and nervous system-specific deletion of Phf6. We show that loss of PHF6 resulted in spontaneous seizures occurring via a neural intrinsic mechanism. Histological and morphological analysis revealed a significant enlargement of the lateral ventricles in adult Phf6-deficient mice, while other brain structures and cortical lamination were normal. Phf6 deficient neural precursor cells showed a reduced capacity for self-renewal and increased differentiation into neurons. Phf6 deficient cortical neurons commenced spontaneous neuronal activity prematurely suggesting precocious neuronal maturation. We show that loss of PHF6 in the foetal cortex and isolated cortical neurons predominantly caused upregulation of genes, including Reln, Nr4a2, Slc12a5, Phip and ZIC family transcription factor genes, involved in neural development and function, providing insight into the molecular effects of loss of PHF6 in the developing brain.

Transcriptome and acetylome profiling identify crucial steps of neuronal differentiation in Rubinstein-Taybi syndrome

Rubinstein-Taybi syndrome (RTS) is a rare and severe genetic developmental disorder characterized by multiple congenital anomalies and intellectual disability. CREBBP and EP300, the two genes known to cause RTS encode transcriptional coactivators with a catalytic lysine acetyltransferase (KAT) activity. Loss of CBP or p300 function results in a deficit in protein acetylation, in particular at histones. In RTS, nothing is known on the consequences of the loss of histone acetylation on the transcriptomic profiles during neuronal differentiation. To address this question, we differentiated induced pluripotent stem cells from RTS patients carrying a recurrent CREBBP mutation that inactivates the KAT domain into cortical and pyramidal neurons. By comparing their acetylome and their transcriptome at different neuronal differentiation time points, we identified 25 specific acetylated histone residues altered in RTS. We also identified the transition between neural progenitors and immature neurons as a critical step of the differentiation process, with a delayed neuronal maturation in RTS. Overall, this study opens new perspectives in the definition of epigenetic biomarkers for RTS, whose methodology could be extended to other chromatinopathies.

Alcohol consumption confers lasting impacts on prefrontal cortical neuron intrinsic excitability and spontaneous neurotransmitter signaling in the aging brain in mice

Both alcohol use disorder (AUD) and cognitive decline include disruption in the balance of excitation and inhibition in the cortex, but the potential role of alcohol use on excitation and inhibition on the aging brain is unclear. We examined the effect of moderate voluntary binge alcohol consumption on the aged, pre-disease neuronal environment by measuring intrinsic excitability and spontaneous neurotransmission on prefrontal cortical pyramidal (excitatory, glutamatergic) and non-pyramidal (inhibitory, GABAergic) neurons following a prolonged period of abstinence from alcohol in mice. Results highlight that binge alcohol consumption has lasting impacts on the electrophysiological properties of prefrontal cortical neurons. A profound increase in excitatory events onto layer 2/3 non-pyramidal neurons following alcohol consumption was seen, along with altered intrinsic excitability of pyramidal neurons, which could have a range of effects on cognitive disorder progression, such as Alzheimer’s Disease, in humans. These results indicate that moderate voluntary alcohol influences the pre-disease environment in aging and highlight the need for further mechanistic investigation into this risk factor.