Cerebellar Granule Cells Research Articles

Behavioral decline in Shank3Δex4–22 mice during early adulthood parallels cerebellar granule cell glutamatergic synaptic changes

BackgroundSHANK3, a gene encoding a synaptic scaffolding protein, is implicated in autism spectrum disorder (ASD) and is disrupted in Phelan-McDermid syndrome (PMS). Despite evidence of regression or worsening of ASD-like symptoms in individuals with PMS, the underlying mechanisms remain unclear. Although Shank3 is highly expressed in the cerebellar cortical granule cells, its role in cerebellar function and contribution to behavioral deficits in ASD models are unknown. This study investigates behavioral changes and cerebellar synaptic alterations in Shank3Δex4–22 mice at two developmental stages.MethodsShank3Δex4–22 wildtype, heterozygous, and homozygous knockout mice lacking exons 4–22 (all functional isoforms) were subjected to a behavioral battery in both juvenile (5–7 weeks old) and adult (3–5 months old) mouse cohorts of both sexes. Immunostaining was used to show the expression of Shank3 in the cerebellar cortex. Spontaneous excitatory postsynaptic currents (sEPSCs) from cerebellar granule cells (CGCs) were recorded by whole-cell patch-clamp electrophysiology.ResultsDeletion of Shank3 caused deficits in motor function, heightened anxiety, and repetitive behaviors. These genotype-dependent behavioral alterations were more prominent in adult mice than in juveniles. Reduced social preference was only identified in adult Shank3Δex4–22 knockout male mice, while self-grooming was uniquely elevated in males across both age groups. Heterozygous mice showed little to no changes in behavioral phenotypes in most behavioral tests. Immunofluorescence staining indicated the presence of Shank3 predominantly in the dendrite-containing rosette-like structures in CGCs, colocalizing with presynaptic markers of glutamatergic mossy fiber. Electrophysiological findings identified a parallel relationship between the age-related exacerbation of behavioral impairments and the enhancement of sEPSC amplitude in CGCs.LimitationsOther behavioral tests of muscle strength (grip strength test), memory (Barnes/water maze), and communication (ultrasonic vocalization), were not performed. Further study is necessary to elucidate how Shank3 modulates synaptic function at the mossy fiber-granule cell synapse in the cerebellum and whether these changes shape the behavioral phenotype.ConclusionsOur findings reveal an age-related exacerbation of behavioral impairments in Shank3Δex4–22 mutant mice. These results suggest that Shank3 may alter the function of glutamatergic receptors at the mossy fiber-cerebellar granule cell synapse as a potential mechanism causing cerebellar disruption in ASD.

Effect of steel fibers on the stress–strain behaviour of aligned steel fiber ultra-high performance concrete under uniaxial compression

The mechanical properties of ultra-high performance concrete (UHPC) can be significantly enhanced by aligning the fibers. Aligned steel fiber UHPC (ASF-UHPC) was fabricated using a uniform magnetic field, yet the corresponding stress-strain relationship has not been extensively studied, hindering accurate calculations. To address this gap, ASF-UHPC was prepared and subsequently subjected to CT scans and uniaxial compression tests to investigate its stress-strain behavior. The analysis of failure mode and stress-strain curves revealed distinct anisotropic characteristics in compressive stresses and fiber distributions. Various steel fiber parameters, including the alignment orientation, volume fraction, and length, were systematically analysed to assess their impact on the material properties. A unit-cell model was developed to elucidate the influence of the fiber alignment orientation on UHPC performance. The results demonstrate that a parallel fiber alignment significantly enhances the elastic modulus, albeit with a Poisson ratio similar to that of the matrix, owing to the limited lateral confinement. Conversely, perpendicular fiber alignment restrains lateral deformation, enhancing the material strength and toughness. Randomly distributed fibers offered a degree of horizontal confinement, whereas inclined fibers induced horizontal thrust, leading to excessive lateral deformation and consequent elevation of the Poisson ratio. Finally, predictive equations for UHPC elastic modulus and compressive strength, along with an analysis model for stress-strain characteristics, were refined taking into account the direction of fiber arrangement.

FUT8 Regulates Cerebellar Neurogenesis and Development Through Maintaining the Level of Neural Cell Adhesion Molecule Cntn2.

Core fucosylation at N-glycans, which is uniquely catalyzed by fucosyltransferase FUT8, plays essential roles in post-translational regulation of protein function. Aberrant core fucosylation leads to neurological disorders in individuals with congenital glycosylation disorders (CDG). However, the underlying mechanisms for these neurological defects remain largely unknown. In this study, we have showed that FUT8 and fucosylation are abundant in cerebellum. Specific deletion of Fut8 in cerebellar granule neuron progenitors (GNPs) results in the impaired proliferation and differentiation of GNPs, as well as the compromised neuronal development, synaptic physiology and motor coordination. Mechanistically, we have showed that Fut8 deficiency reduced Contactin 2 (Cntn2) expression, a member of neural cell adhesion molecules (NCAMs). Furthermore, ectopic Cntn2 can rescue the neuronal defects induced by Fut8 deficiency. Collectively, our study has revealed the important roles of FUT8 and core fucosylation in regulating cerebellar development and function through modulating Cntn2 expression.

Ezh2 Delays Activation of Differentiation Genes During Normal Cerebellar Granule Neuron Development and in Medulloblastoma.

Medulloblastoma (MB) is the most common malignant brain tumour in children. The Sonic Hedgehog (SHH)-medulloblastoma subtype arises from the cerebellar granule neuron lineage. Terminally differentiated neurons are incapable of undergoing further cell division, so an effective treatment for this tumour could be to force neuronal differentiation. Differentiation therapy provides a potential alternative for patients with medulloblastoma who harbor mutations that impair cell death pathways (TP53), which is associated a with high mortality. To this end, our goal was to explore epigenetic regulation of cerebellar granule neuron differentiation in medulloblastoma cells. Key regulators were discovered using chromatin immunoprecipitation with high-throughput sequencing. DNA-bound protein and chromatin protein modifications were investigated across all genes. We discovered that Ezh2-mediated tri-methylation of the H3 histone (H3K27me3), occurred on more than half of the 787 genes whose transcription normally increases as granule neurons terminally differentiate. Conditional knockout of Ezh2 led to early initiation of differentiation in granule neuron precursors (GNPs), but only after cell cycle exit had occurred. Similarly, in MB cells, neuronal differentiation could be induced by preventing H3K27me3 modifications using an Ezh2 inhibitor (UNC1999), but only when UNC1999 was combined with forced cell cycle exit driven by a CDK4/6 inhibitor (Palbociclib). Ezh2 emerges as a powerful restraint upon post-mitotic differentiation during normal GNP development and combination of Ezh2 inhibition with cell cycle exit leads to MB cell differentiation.

Anisotropic hydrogel sensors with muscle-like structures based on high-absorbent alginate fibers

Hydrogel sensors have attracted much attention as they play a critical role in health monitoring, multifunctional electronic skin, and human-machine interfaces. However, the isotropic structure makes existing hydrogel sensors exhibit isotropic sensing performance. Therefore, it is a challenge to fabricate hydrogels with human tissue-like structures to achieve anisotropic sensing performance. Herein, we proposed a novel method to prepare anisotropic hydrogel sensors using high-absorbent alginate fibers. The anisotropic hydrogel, HAFG@CNTs, was prepared by adsorbing carbon nanotubes on high-absorbent alginate fibers and immobilized using polyacrylamide bonds. The hydrogel had anisotropic mechanical properties and anisotropic ionic conductivity. The modulus and toughness in the parallel fiber direction were 2.31 and 3.75 times higher than those in the perpendicular fiber direction, respectively, and the sensitivity of the parallel fiber direction was higher than that of the vertical direction when strain occurred. In addition, machine learning algorithms were used to predict and classify different action signals obtained from HAFG@CNTs with an accuracy of up to 98.18 %. These advantages offer great potential for applying HAFG@CNTs to wearable devices and medical monitoring.

Microstructure and crystal modulus of polyamide 4 α-form in the direction parallel to the chain axis

Polyamide 4 (PA4) is a lactam-based aliphatic synthetic polymer with promising properties and admirable biodegradability. In this study, oriented PA4 fibers were fabricated by dry spinning followed by thermal drawing. Elastic modulus (El) of the crystalline regions (crystal modulus) of PA4 fibers in the direction parallel to the chain axis was evaluated from the X-ray diffraction peak shift owing to the tensile stress. The apparent El value of PA4 is 67 GPa for meridional 004 reflection and 119 GPa for 0010 reflection, respectively. The reason for the different El is that the decrease of crystallite size of PA4 by the applied stress brought extra shifts of 004 reflection peak to lower angle based on the Laue factor. In contrast, 0010 reflection peak received less effects from this effect, and the El value of 119 GPa obtained from 0010 reflection was considered to be a reliable value. The observed El value of PA4 is much lower than the calculated values assuming fully extended planar zigzag skeleton for PA4. Thus the low El value is attributed to the highly contraction (−1.9 %) from the fully extended conformation as observed for another polyamides.

TMOD-19. GERMLINEELP1 DEFICIENCY SENSITIZES CEREBELLAR GRANULE NEURON PROGENITORS TO SHH MEDULLOBLASTOMA

Abstract Germline loss-of-function (LOF) variants in Elongator complex protein 1 (ELP1) are the most prevalent predisposing genetic events observed in medulloblastoma (MB), accounting for 30% of the Sonic Hedgehog 3 subtype (SHH-3). Molecularly, ELP1-associated SHH-MBs acquire somatic PTCH1 mutations in >80% of cases, and universal loss-of-heterozygosity of the wild-type ELP1 and PTCH1 alleles through loss of chromosome-arm 9q, resulting in their biallelic inactivation. Notably, germline ELP1 LOF occurs mutually exclusive with somatic/germline TP53 mutations in the SHH-3 subtype, suggesting that genetic perturbation of either ELP1 or TP53 may promote similar downstream oncogenic consequences in cerebellar granule neuron progenitors (GNPs), the accepted cellular origin of SHH-MB. Despite these findings, the molecular, biochemical, and cellular mechanism(s) by which ELP1-deficiency provokes malignant pathogenesis remain unknown. In this study, we sought to close this knowledge gap and functionally determine why children harboring pathogenic ELP1 germline variants are at an increased risk of developing SHH-MB. Mice were genetically engineered to mimic heterozygous Elp1 LOF (Elp1HET). We studied the effect of loss of ELP1 in GNPs using a combination of molecular profiling, immunophenotyping, and cellular assays. GNPs from Elp1HET exhibited a spectrum of molecular and biochemical hallmarks of malignant transformation including increased DNA replication stress, DNA damage, accelerated cell cycle progression, and stalled differentiation. Orthotopic transplantation of Elp1HET GNPs engineered to harbor somatic Ptch1 inactivation yielded SHH-MB-like tumors with compromised p53 signaling, providing an explanation for the specificity of ELP1-associated tumors in SHH-3, and their exclusivity with TP53-mutant tumors. Treatment of ELP1-mutant patient-derived xenografts with an FDA-approved MDM2 inhibitor reactivated p53-dependent apoptosis and extended survival. Collectively, our findings functionally substantiate the role of ELP1 deficiency in predisposition to SHH-3 MB and nominate therapeutic strategies to overcome p53 inhibition as a rational treatment option.

An EED/PRC2-H19 Loop Regulates Cerebellar Development.

EED (embryonic ectoderm development) is a core subunit of the polycomb repressive complex 2 (PRC2), which senses the trimethylation of histone H3 lysine 27 (H3K27). However, its biological function in cerebellar development remains unknown. Here, we show that EED deletion from neural stem cells (NSCs) or cerebellar granule cell progenitors (GCPs) leads to reduced GCPs proliferation, cell death, cerebellar hypoplasia, and motor deficits in mice. Joint profiling of transcripts and ChIP-seq analysis in cerebellar granule cells reveals that EED regulates bunches of genes involved in cerebellar development. EED ablation exhibits overactivation of a developmental repressor long non-coding RNA H19. Importantly, an obvious H3K27ac enrichment is found at Ctcf, a trans-activator of H19, and H3K27me3 enrichment at the H19 imprinting control region (ICR), suggesting that EED regulates H19 in an H3K27me3-dependent manner. Intriguingly, H19 deletion reduces EED expression and the reprogramming of EED-mediated H3K27me3 profiles, resulting in increased proliferation, differentiation, and decreased apoptosis of GCPs. Finally, molecular and genetic evidence provides that increased H19 expression is responsible for cerebellar hypoplasia and motor defects in EED mutant mice. Thus, this study demonstrates that EED, H19 forms a negative feedback loop, which plays a crucial role in cerebellar morphogenesis and controls cerebellar development.

Bimetallic ZIF membranes growing on the inner-surface of ZnO ceramic hollow fibers for gas separation

Bimetallic ZIF membranes offer additional functionalities compared to single-metal ZIFs membranes. However, the preparation of ZIF membranes through a facile and reproducible process remains a significant challenge. In this work, a high-quality bimetallic CoxZn1−x-ZIF membrane was successfully synthesized using a ZnO support-activation and hydrothermal approach. The effects of the length of ZnO hollow fiber support, surface activation, different Zn/Co molar ratios in the MOF framework and operating conditions on the membrane performance were carefully investigated. Experimental results indicate that the incorporation of two metals (Co and Zn) in the ZIF membrane can tune the ZIF pore framework to improve the gas selectivity while maintaining the general crystal structure of the single metal ZIF-67. The optimized bimetallic Co0.3Zn0.7-ZIF membrane exhibited a high H2/CH4 separation factor of 18.3 with a H2 permeance of approximately 1.05 × 10−7 mol·m−2·s−1·Pa−1, surpassing the single-metal ZIF-67 membrane. Noteworthy that the Co0.3Zn0.7-ZIF membrane demonstrated excellent long-term operation stability for 200 h and good thermal cycling stability for more than 10 days. Furthermore, the mechanical and hydrothermal stability test results imply that bimetallic ZIF membrane exhibited better stability than single metal ZIF-67 membrane. Our results also indicate that three parallel bimetallic ZIF hollow fiber membranes can be prepared in one autoclave using the similar amount of nutrient solution for one membrane growth and these membranes exhibited much similar separation properties. The employed method for bimetallic ZIF hollow fiber membrane has a very good reproducibility and scaling up capacity, paving the way for practical application.

Non-allometric expansion and enhanced compartmentalization of Purkinje cell dendrites in the human cerebellum.

Purkinje cell (PC) dendrites are optimized to integrate the vast cerebellar input array and drive the sole cortical output. PCs are classically seen as stereotypical computational units, yet mouse PCs are morphologically diverse and those with multi-branched structure can receive non-canonical climbing fiber (CF) multi-innervation that confers independent compartment-specific signaling. While otherwise uncharacterized, human PCs are universally multi-branched. Do they exceed allometry to achieve enhanced integrative capacities relative to mouse PCs? To answer this, we used several comparative histology techniques in adult human and mouse to analyze cellular morphology, parallel fiber (PF) and CF input arrangement, and regional PC demographics. Human PCs are substantially larger than previously described; they exceed allometric constraint by cortical thickness and are the largest neuron in the brain with 6-7cm total dendritic length. Unlike mouse, human PC dendrites ramify horizontally to form a multi-compartment motif that we show can receive multiple CFs. Human spines are denser (6.9 vs 4.9 spines/μm), larger (~0.36 vs 0.29μm), and include an unreported 'spine cluster' structure-features that may be congruent with enhanced PF association and amplification as human-specific adaptations. By extrapolation, human PCs may receive 500,000 to 1 million synaptic inputs compared with 30-40,000 in mouse. Collectively, human PC morphology and input arrangement is quantitatively and qualitatively distinct from rodent. Multi-branched PCs are more prevalent in posterior and lateral cerebellum, co-varying with functional boundaries, supporting the hypothesis that this morphological motif permits expanded input multiplexing and may subserve task-dependent needs for input association.

Gravity-driven flow of liquid bridges between vertical fibres

Liquid bridges are formed when a flowing liquid interacts with multiple parallel fibres, as relevant to heat and mass transfer applications that utilize flow down fibre arrays. We perform a comprehensive experimental study of flowing liquid bridges between two vertical fibres whose spacing is controlled dynamically in our experimental apparatus. The bridge patterns exhibit a regular periodic spacing typical of absolute instability for low flow rates, but become spatially inhomogeneous above a critical flow rate where the base flow is convectively unstable. The shapes of individual bridges and their associated dynamics are measured, as they depend upon the liquid properties, and fibre geometry/spacing. The bridge length scales similarly to static bridges between parallel fibres. The bridge dynamics exhibits a dependence on viscosity and scale with the impedance. A simple energy balance is used to derive a scaling relationship for the bridge velocity that captures the general trend of our experimental data. Finally, we demonstrate that these scalings similarly apply when the fibres are dynamically separated or brought together.

An increase in reactive oxygen species underlies neonatal cerebellum repair.

The neonatal mouse cerebellum shows remarkable regenerative potential upon injury at birth, wherein a subset of Nestin-expressing progenitors (NEPs) undergoes adaptive reprogramming to replenish granule cell progenitors that die. Here, we investigate how the microenvironment of the injured cerebellum changes upon injury and contributes to the regenerative potential of normally gliogenic-NEPs and their adaptive reprogramming. Single cell transcriptomic and bulk chromatin accessibility analyses of the NEPs from injured neonatal cerebella compared to controls show a temporary increase in cellular processes involved in responding to reactive oxygen species (ROS), a known damage-associated molecular pattern. Analysis of ROS levels in cerebellar tissue confirm a transient increased one day after injury at postanal day 1, overlapping with the peak cell death in the cerebellum. In a transgenic mouse line that ubiquitously overexpresses human mitochondrial catalase (mCAT), ROS is reduced 1 day after injury to the granule cell progenitors, and we demonstrate that several steps in the regenerative process of NEPs are curtailed leading to reduced cerebellar growth. We also provide evidence that microglia are involved in one step of adaptive reprogramming by regulating NEP replenishment of the granule cell precursors. Collectively, our results highlight that changes in the tissue microenvironment regulate multiple steps in adaptative reprogramming of NEPs upon death of cerebellar granule cell progenitors at birth, highlighting the instructive roles of microenvironmental signals during regeneration of the neonatal brain.

Optical networking that exploits massive wavelength/spectrum and spatial parallelisms

As DWDM transmission offers enhanced wavelength/spectrum parallelism, the capacity of optical networks has been substantially increased. Due to the theoretical capacity limit of C-band transmission over single-mode fibers, research into new frequency bands and parallel fibers has become very active. However, the hardware scale of current optical cross-connect nodes will explode with greater wavelength/spectrum and spatial parallelism. Three optical node/network architectures are presented in this paper that take advantage of one or both of these parallelism technologies. These architectures will provide a baseline for cost-effective and bandwidth-abundant future optical networks based on massive parallelism.

A Flexible Pressure Sensor With Parallel Fiber Structure for Wireless Capsule Detection

A Flexible Pressure Sensor With Parallel Fiber Structure for Wireless Capsule Detection

Experimental Study of Fiber-Optic Temperature Sensor Based on Dual FSIs

To improve the sensitivity measurement of temperature sensors, a fiber optic temperature sensor structure based on the harmonic Vernier effect with two parallel fiber Sagnac interferometers (FSIs) is designed, and theoretical analysis and experimental testing are conducted. The FSI consisting of two polarization maintaining fibers (PMFs) with lengths of 13.62 m and 15.05 m respectively is used to achieve the basic Vernier effect. Then by changing the length of one PMF to approximately i times that of the others, the FSI composed of two PMFs of 7.1 m and 15.05 m is used to achieve the first-order harmonic Vernier effect. Afterward, temperature sensing tests are conducted to observe the wavelength drift during temperature changes and ultimately achieve high sensitivity. The experimental results show that the temperature sensitivity of the sensor based on the first-order harmonic Vernier effect is −28.89 nm/°C, which is 17.09 times that of a single FSI structure (−1.69 nm/°C) and 1.84 times that of the sensitivity generated by the structure based on the basic Vernier effect (−15.69 nm/°C). The experimental results are consistent with the theoretical analysis. The structure proposed in this paper achieves drift measurement of 0.1 °C variation based on 1 °C drift, making the fiber optic temperature sensor applicable to related fields that require high precision temperature. The proposed temperature sensor has the simple structure, low production cost, high sensitivity, and broad application prospects.

Antagonistic action of Siah2 and Pard3/JamC to promote germinal zone exit of differentiated cerebellar granule neurons by modulating Ntn1 signaling via Dcc.

Exiting a germinal zone (GZ) initiates a cascade of events that promote neuronal maturation and circuit assembly. Developing neurons and their progenitors must interpret various niche signals-such as morphogens, guidance molecules, extracellular matrix components, and adhesive cues-to navigate this region. How differentiating neurons integrate and adapt to multiple cell-extrinsic niche cues with their cell-intrinsic machinery in exiting a GZ is unknown. We establish cooperation between cell polarity-regulated adhesion and Netrin-1 (Ntn-1) signaling comprises a coincidence detection circuit repelling maturing neurons from their GZ. In this circuit, the Partitioning defective 3 (Pard3) polarity protein and Junctional adhesion molecule-C (JamC) adhesion protein promote, while the Seven in absentia 2 (Siah2) ubiquitin ligase inhibits, Deleted in colorectal cancer (Dcc) receptor surface recruitment to gate differentiation linked repulsion to GZ Ntn-1. These results demonstrate cell polarity as a central integrator of adhesive- and guidance cues cooperating to spur GZ exit.

Development of a sensor to detect methylmercury toxicity

Methylmercury (MeHg) is a well-known neurotoxicant that induces various cellular functions depending on cellular- and developmental-specific vulnerabilities. MeHg has a high affinity for selenol and thiol groups, thus impairing the antioxidant system. Such affinity characteristics of MeHg led us to develop sensor vectors to assess MeHg toxicity. In this study, MeHg-mediated defects in selenocysteine (Sec) incorporation were demonstrated using thioredoxin reductase 1 cDNA fused with the hemagglutinin tag sequence at the C-terminus. Taking advantage of such MeHg-mediated defects in Sec incorporation, a cDNA encoding luciferase with a Sec substituted for cysteine-491 was constructed. This construct showed MeHg-induced decreases in signaling in a dose-dependent manner. To directly detect truncated luciferase under MeHg exposure, we further constructed a new sensor vector fused with a target for proteasomal degradation. However, this construct was inadequate because of the low rate of Sec insertion, even in the absence of MeHg. Finally, a Krab transcriptional suppressor fused with Sec was constructed and assessed to demonstrate MeHg-dependent increases in signal intensity. We confirmed that the vector responded specifically and in a dose-dependent manner to MeHg in cultured cerebellar granule cells. This vector is expected to allow monitoring of MeHg-specific toxicity via spatial and temporal imaging.

Heterogeneity in Slow Synaptic Transmission Diversifies Purkinje Cell Timing.

The cerebellum plays an important role in diverse brain functions, ranging from motor learning to cognition. Recent studies have suggested that molecular and cellular heterogeneity within cerebellar lobules contributes to functional differences across the cerebellum. However, the specific relationship between molecular and cellular heterogeneity and diverse functional outputs of different regions of the cerebellum remains unclear. Here, we describe a previously unappreciated form of synaptic heterogeneity at parallel fiber synapses to Purkinje cells in the mouse cerebellum (both sexes). In contrast to uniform fast synaptic transmission, we found that the properties of slow synaptic transmission varied by up to threefold across different lobules of the mouse cerebellum, resulting in surprising heterogeneity. Depending on the location of a Purkinje cell, the time of peak of slow synaptic currents varied by hundreds of milliseconds. The duration and decay time of these currents also spanned hundreds of milliseconds, based on lobule. We found that, as a consequence of the heterogeneous synaptic dynamics, the same brief input stimulus was transformed into prolonged firing patterns over a range of timescales that depended on Purkinje cell location.

Orientation effect of chopped steel fiber on tribological performance of very low metallic brake pads: An interface study

The orientation effect of chopped tiny steel fibres (length < 3 mm; diameter < 200 µm) in brake pads parallel (NAPA) to the sliding direction is studied using two different methods. Inverting the specimen during testing yields fibre perpendicular (NAPE) to the sliding direction, which is compared to commercial random-oriented fibre pads (NARA). The orientation coefficient value of near unity is achieved only in NAPA. NAPA and NAPE have a lower density than NARA by 13.2% due to less than 54.55% of steel fibres in the formulation. More and larger plateaus stabilized friction in NARA, utilising the elongation properties of parallel steel fibres, than in NAPE, which produced only tiny plateaus. However, the wear resistance decreases when the sliding path or direction changes from parallel to perpendicular. The measurement of thickness loss is misleading during wear because of the swelling effect, and hence energy requirements are considered. The energy required to wear 1 cc of specimen in the NAPE is 23.78% greater than that in the NAPA, and hence wear resistance is better. Adhesion followed by delamination at elevated temperatures are the dominant wear mechanisms in NAPA, whereas abrasion is dominant in NAPE. Thus, semi-metallic performance can be obtained in a very low metallic pad by orienting these fibres.

Behavioral regression in shank3Δex4-22 mice during early adulthood corresponds to cerebellar granule cell glutamatergic synaptic changes.

Shank3, a gene encoding a synaptic scaffolding protein, is implicated in autism spectrum disorder (ASD) and is disrupted in Phelan-McDermid syndrome (PMS). Despite evidence of regression or worsening of ASD-like symptoms in individuals with PMS, the underlying mechanisms remain unclear. Although shank3 is highly expressed in the cerebellar cortical granule cells, its role in cerebellar function and contribution to behavioral deficits in ASD models are unknown. This study investigates behavioral changes and cerebellar synaptic alterations in shank3 Δex4-22 mice at two developmental stages. Shank3 Δex4-22 wildtype, heterozygous, and homozygous knockout mice lacking exons 4-22 (all functional isoforms) were subjected to a behavioral battery in both juvenile (5-7 weeks old) and adult (3-5 months old) mouse cohorts of both sexes. Immunostaining was used to show the expression of SHANK3 in the cerebellar cortex. Spontaneous excitatory postsynaptic currents (sEPSCs) from cerebellar granule cells (CGCs) were recorded by whole-cell patch-clamp electrophysiology. Deletion of shank3 ex4-22 caused deficits in motor function, heightened anxiety, and repetitive behaviors. These genotype-dependent behavioral alterations were more prominent in adult mice than in juveniles. Reduced social preference was only identified in adult shank3 Δex4-22 knockout mice and self-grooming was uniquely elevated only in males across both age groups. Immunofluorescence staining indicates the presence of SHANK3 predominantly in the dendrite-containing rosette-like structures in CGCs, colocalizing with presynaptic markers of glutamatergic mossy fiber. Electrophysiological findings identify a parallel relationship between the age-related exacerbation of behavioral impairments and the enhancement of sEPSC amplitude in CGCs. Other behavioral tests of muscle strength (grip strength test), memory (Barnes/water maze), and communication (ultrasonic vocalization), were not performed. Further study is necessary to elucidate how SHANK3 modulates synaptic function at the mossy fiber-granule cell synapse in the cerebellum. Our findings reveal an age-related exacerbation of behavioral impairments in shank3 Δex4-22 mutant mice. These results suggest that SHANK3 may play a role in maintaining glutamatergic receptors and synapses in CGCs, as well as the potential involvement of the cerebellum in ASD.