Ganglioside GT1b prevents selective spinal synapse removal following peripheral nerve injury.

After peripheral nerve injury, the structure of the spinal cord is actively regulated by glial cells, contributing to the chronicity of neuropathic pain. However, the mechanism by which peripheral nerve injury leads to synaptic imbalance remains elusive. Here, we use a pH-reporter system and find that nerve injury triggers a reorganization of excitatory synapses that is influenced by the accumulation of the ganglioside GT1b at afferent terminals.

25-Hydroxycholesterol modulates microglial function and exacerbates Alzheimer's disease pathology: mechanistic insights and therapeutic potential of cholesterol esterification inhibition.

This study investigates the role of 25-hydroxycholesterol (25HC), a metabolite produced by cholesterol hydroxylase encoded by the Ch25h gene, in modulating microglial function and its potential implications in Alzheimer's disease (AD) pathology. We demonstrated that 25HC impairs microglial surveillance, reduces phagocytic capacity, and increases the production of pro-inflammatory cytokines. In vivo two-photon microscopy revealed that 25HC administration diminishes microglial response to brain lesions, while flow cytometry confirmed reduced phagocytosis in both in vivo and in vitro models.

Aberrant ERK signaling in astrocytes impairs learning and memory in RASopathy-associated BRAF mutant mouse models.

RAS/MAPK pathway mutations often induce RASopathies with overlapping features, such as craniofacial dysmorphology, cardiovascular defects, dermatologic abnormalities, and intellectual disabilities. Although B-Raf proto-oncogene (BRAF) mutations are associated with cardio-facio-cutaneous (CFC) syndrome and Noonan syndrome, it remains unclear how these mutations impair cognition. Here, we investigated the underlying neural mechanisms using several mouse models harboring a gain-of-function BRAF mutation (K499E) discovered in RASopathy patients.

Hippocampal tau-induced GRIN3A deficiency in Alzheimer's disease.

Alzheimer's disease (AD) is characterized by significant alterations in hippocampal function and structure, but the molecular mechanisms underlying the hippocampal region remain elusive. We integrated multiple transcriptome datasets including human or rat hippocampus (GSE173955, GSE129051, GSE84422) to identify candidate genes. Subsequent analyses including gene ontology analysis and protein-protein interaction mapping were performed to identify key genes and pathways.

Author Correction: Microglia-synapse engulfment via PtdSer-TREM2 ameliorates neuronal hyperactivity in Alzheimer's disease models.

[Image: see text]

FGFR3 drives Aβ-induced tau uptake.

The amyloid cascade hypothesis suggests that amyloid beta (Aβ) contributes to initiating subsequent tau pathology in Alzheimer's disease (AD). However, the underlying mechanisms through which Aβ contributes to tau uptake and propagation remain poorly understood. Here, we show that preexisting amyloid pathology accelerates the uptake of extracellular tau into neurons.

CRIF1 deficiency induces FOXP3 inflammatory non-suppressive regulatory T cells, thereby promoting antitumor immunity.

Recently identified human FOXP3CD45RA inflammatory non-suppressive (INS) cells produce proinflammatory cytokines, exhibit reduced suppressiveness, and promote antitumor immunity unlike conventional regulatory T cells (T). In spite of their implication in tumors, the mechanism for generation of FOXP3CD45RA INS cells in vivo is unclear. We showed that the FOXP3CD45RA cells in human tumors demonstrate attenuated expression of CRIF1, a vital mitochondrial regulator.

nArgBP2 together with GKAP and SHANK3 forms a dynamic layered structure.

nArgBP2, a protein whose disruption is implicated in intellectual disability, concentrates in excitatory spine-synapses. By forming a triad with GKAP and SHANK, it regulates spine structural rearrangement. We here find that GKAP and SHANK3 concentrate close to the synaptic contact, whereas nArgBP2 concentrates more centrally in the spine.

High-resolution open-top axially swept light sheet microscopy.

Background: Open-top light-sheet microscopy (OT-LSM) is a specialized microscopic technique for the high-throughput cellular imaging of optically cleared, large-sized specimens, such as the brain. Despite the development of various OT-LSM techniques, achieving submicron resolution in all dimensions remains.

Results: We developed a high-resolution open-top axially swept LSM (HR-OTAS-LSM) for high-throughput and high-resolution imaging in all dimensions.

Microglia-synapse engulfment via PtdSer-TREM2 ameliorates neuronal hyperactivity in Alzheimer's disease models.

Neuronal hyperactivity is a key feature of early stages of Alzheimer's disease (AD). Genetic studies in AD support that microglia act as potential cellular drivers of disease risk, but the molecular determinants of microglia-synapse engulfment associated with neuronal hyperactivity in AD are unclear. Here, using super-resolution microscopy, 3D-live imaging of co-cultures, and in vivo imaging of lipids in genetic models, we found that spines become hyperactive upon Aβ oligomer stimulation and externalize phosphatidylserine (ePtdSer), a canonical "eat-me" signal.

Formation of aggresomes with hydrogel-like characteristics by proteasome inhibition.

The spatiotemporal sequestration of misfolded proteins is a mechanism by which cells counterbalance proteome homeostasis upon exposure to various stress stimuli. Chronic inhibition of proteasomes results in a large, juxtanuclear, membrane-less inclusion, known as the aggresome. Although the molecular mechanisms driving its formation, clearance, and pathophysiological implications are continuously being uncovered, the biophysical aspects of aggresomes remain largely uncharacterized.

L-type Ca channels mediate regulation of glutamate release by subthreshold potential changes.

Subthreshold depolarization enhances neurotransmitter release evoked by action potentials and plays a key role in modulating synaptic transmission by combining analog and digital signals. This process is known to be Ca dependent. However, the underlying mechanism of how small changes in basal Ca caused by subthreshold depolarization can regulate transmitter release triggered by a large increase in local Ca is not well understood.

Biomolecular condensate assembly of nArgBP2 tunes its functionality to manifest the structural plasticity of dendritic spines.

nArgBP2, a candidate gene for intellectual disability, is a postsynaptic protein critical for dendritic spine development and morphogenesis, and its knockdown (KD) in developing neurons severely impairs spine-bearing excitatory synapse formation. Surprisingly, nArgBP2 KD in mature neurons did not cause morphological defects in the existing spines at rest, raising questions of how it functions in mature neurons. We found that unlike its inaction at rest, nArgBP2 KD completely inhibited the enlargement of dendritic spines during chemically induced long-term potentiation (cLTP) in mature neurons.

DYRK3 phosphorylates SNAPIN to regulate axonal retrograde transport and neurotransmitter release.

Among the five members of the dual-specificity tyrosine-phosphorylation-regulated kinase (DYRK) family, the cellular functions of DYRK3 have not been fully elucidated. Some studies have indicated limited physiological roles and substrates of DYRK3, including promotion of glioblastoma, requirement in influenza virus replication, and coupling of stress granule condensation with mammalian target of rapamycin complex 1 signaling. Here, we demonstrate that serum deprivation causes a decrease in intracellular DYRK3 levels via the proteolytic autophagy pathway, as well as the suppression of DYRK3 gene expression.

An Alternative Splicing Variant of the Mixed-Lineage Leukemia 5 Protein Is a Cellular Adhesion Receptor for ScaA of Orientia tsutsugamushi.

Scrub typhus is a mite-borne disease caused by the obligately intracellular bacterium Orientia tsutsugamushi. We previously demonstrated that ScaA, an autotransporter membrane protein of O. tsutsugamushi, is commonly shared in various genotypes and involved in adherence to host cells.

Fast volumetric imaging with line-scan confocal microscopy by electrically tunable lens at resonant frequency.

In microscopic imaging of biological tissues, particularly real-time visualization of neuronal activities, rapid acquisition of volumetric images poses a prominent challenge. Typically, two-dimensional (2D) microscopy can be devised into an imaging system with 3D capability using any varifocal lens. Despite the conceptual simplicity, such an upgrade yet requires additional, complicated device components and usually suffers from a reduced acquisition rate, which is critical to properly document rapid neurophysiological dynamics.

Deep learning enables reference-free isotropic super-resolution for volumetric fluorescence microscopy.

Volumetric imaging by fluorescence microscopy is often limited by anisotropic spatial resolution, in which the axial resolution is inferior to the lateral resolution. To address this problem, we present a deep-learning-enabled unsupervised super-resolution technique that enhances anisotropic images in volumetric fluorescence microscopy. In contrast to the existing deep learning approaches that require matched high-resolution target images, our method greatly reduces the effort to be put into practice as the training of a network requires only a single 3D image stack, without a priori knowledge of the image formation process, registration of training data, or separate acquisition of target data.

Optimized single-step optical clearing solution for 3D volume imaging of biological structures.

Various optical clearing approaches have been introduced to meet the growing demand for 3D volume imaging of biological structures. Each has its own strengths but still suffers from low transparency, long incubation time, processing complexity, tissue deformation, or fluorescence quenching, and a single solution that best satisfies all aspects has yet been developed. Here, we develop OptiMuS, an optimized single-step solution that overcomes the shortcomings of the existing aqueous-based clearing methods and that provides the best performance in terms of transparency, clearing rate, and size retention.

Sodium Cholate-Based Active Delipidation for Rapid and Efficient Clearing and Immunostaining of Deep Biological Samples.

Recent surges of optical clearing provided anatomical maps to understand structure-function relationships at organ scale. Detergent-mediated lipid removal enhances optical clearing and allows efficient penetration of antibodies inside tissues, and sodium dodecyl sulfate (SDS) is the most common choice for this purpose. SDS, however, forms large micelles and has a low critical micelle concentration (CMC).

SGIP1α, but Not SGIP1, is an Ortholog of FCHo Proteins and Functions as an Endocytic Regulator.

Src homology 3-domain growth factor receptor-bound 2-like interacting protein 1 (SGIP1), originally known as a regulator of energy homeostasis, was later found to be an ortholog of Fer/Cip4 homology domain-only (FCHo) proteins and to function during endocytosis. SGIP1α is a longer splicing variant in mouse brains that contains additional regions in the membrane phospholipid-binding domain (MP) and C-terminal region, but functional consequences with or without additional regions between SGIP1 and SGIP1α remain elusive. Moreover, many previous studies have either inadvertently used SGIP1 instead of SGIP1α or used the different isoforms with or without additional regions indiscriminately, resulting in further confusion.

DXplorer: A Unified Visualization Framework for Interactive Dendritic Spine Analysis Using 3D Morphological Features.

Dendritic spines are dynamic, submicron-scale protrusions on neuronal dendrites that receive neuronal inputs. Morphological changes in the dendritic spine often reflect alterations in physiological conditions and are indicators of various neuropsychiatric conditions. However, owing to the highly dynamic and heterogeneous nature of spines, accurate measurement and objective analysis of spine morphology are major challenges in neuroscience research.

Multivalent electrostatic pi-cation interaction between synaptophysin and synapsin is responsible for the coacervation.

We recently showed that synaptophysin (Syph) and synapsin (Syn) can induce liquid-liquid phase separation (LLPS) to cluster small synaptic-like microvesicles in living cells which are highly reminiscent of SV cluster. However, as there is no physical interaction between them, the underlying mechanism for their coacervation remains unknown. Here, we showed that the coacervation between Syph and Syn is primarily governed by multivalent pi-cation electrostatic interactions among tyrosine residues of Syph C-terminal (Ct) and positively charged Syn.

Open-top axially swept light-sheet microscopy.

Open-top light-sheet microscopy (OT-LSM) is a specialized microscopic technique for high throughput cellular imaging of large tissue specimens including optically cleared tissues by having the entire optical setup below the sample stage. Current OT-LSM systems had relatively low axial resolutions by using weakly focused light sheets to cover the imaging field of view (FOV). In this report, open-top axially swept LSM (OTAS-LSM) was developed for high-throughput cellular imaging with improved axial resolution.

SCAMP5 mediates activity-dependent enhancement of NHE6 recruitment to synaptic vesicles during synaptic plasticity.

Na(K)/H exchanger 6 (NHE6) on synaptic vesicle (SV) is critical for the presynaptic regulation of quantal size at the glutamatergic synapses by converting the chemical gradient (ΔpH) into membrane potential (Δψ) across the SV membrane. We recently found that NHE6 directly interacts with secretory carrier membrane protein 5 (SCAMP5), and SCAMP5-dependent recruitment of NHE6 to SVs controls the strength of synaptic transmission by modulation of quantal size of glutamate release at rest. It is, however, unknown whether NHE6 recruitment by SCAMP5 plays a role during synaptic plasticity.