Alterations in immune cell heterogeneities in the brain of aged zebrafish using single-cell resolution.

Immunocytes, including the microglia, are crucial in the neurodegenerative process in old people. However, the understanding of regarding microglia heterogeneity and other involved immunocytes remains elusive. We analyzed 26,456 immunocytes from 12-and 26-month-old zebrafish brains at single-cell resolution.

Brain milieu induces early microglial maturation through the BAX-Notch axis.

Microglia are derived from primitive myeloid cells and gain their early identity in the embryonic brains. However, the mechanism by which the brain milieu confers microglial maturation signature remains elusive. Here, we demonstrate that the bax zebrafish and Bax mouse embryos exhibit similarly defective early microglial maturation.

Macrophages Rapidly Seal off the Punctured Zebrafish Larval Brain through a Vital Honeycomb Network Structure.

There is accumulating evidence that macrophages play additional important roles in tissue damage besides their typical phagocytosis. Although the aggregation of macrophages on injured sites has long been observed, few researchers have focused on the role of the overall structure of macrophage aggregation. In this study, we developed a standardized traumatic brain injury (TBI) model in zebrafish larvae to mimic edema and brain tissue spillage symptoms after severe brain trauma.

Nrf2 dictates the neuronal survival and differentiation of embryonic zebrafish harboring compromised alanyl-tRNA synthetase.

tRNA synthetase deficiency leads to unfolded protein responses in neuronal disorders; however, its function in embryonic neurogenesis remains unclear. This study identified an aars1cq71/cq71 mutant zebrafish allele that showed increased neuronal apoptosis and compromised neurogenesis. aars1 transcripts were highly expressed in primary neural progenitor cells, and their aberration resulted in protein overloading and activated Perk.

Synaptic repair and vision restoration in advanced degenerating eyes by transplantation of retinal progenitor cells.

Stem cell transplantation shows enormous potential for treatment of incurable retinal degeneration (RD). To determine if and how grafts connect with the neural circuits of the advanced degenerative retina (ADR) and improve vision, we perform calcium imaging of GCaMP5-positive grafts in retinal slices. The organoid-derived C-Kit/SSEA1 (C-Kit) retinal progenitor cells (RPCs) become synaptically organized and build spontaneously active synaptic networks in three major layers of ADR.

Localization of the WD repeat-containing protein 5 to the Virion Assembly Compartment Facilitates Human Cytomegalovirus Assembly.

We previously reported that human cytomegalovirus (HCMV) utilizes the cellular protein WD repeat-containing protein 5 (WDR5) to facilitate capsid nuclear egress. Here, we further show that HCMV infection results in WDR5 localization in a juxtanuclear region, and that its localization to this cellular site is associated with viral replication and late viral gene expression. Furthermore, WDR5 accumulated in the virion assembly compartment (vAC) and co-localized with vAC markers of gamma-tubulin (γ-tubulin), early endosomes, and viral vAC marker proteins pp65, pp28, and glycoprotein B (gB).

Anterograde Viral Tracer Herpes Simplex Virus 1 Strain H129 Transports Primarily as Capsids in Cortical Neuron Axons.

The features of herpes simplex virus 1 (HSV-1) strain 129 (H129), including natural neurotropism and anterograde transneuronal trafficking, make it a potential tool for anterograde neural circuitry tracing. Recently anterograde polysynaptic and monosynaptic tracers were developed from H129 and have been applied for the identification of novel connections and functions of different neural circuitries. However, how H129 viral particles are transported in neurons, especially those of the central nervous system, remains unclear.

Microglia Mediate Synaptic Material Clearance at the Early Stage of Rats With Retinitis Pigmentosa.

Resident microglia are the main immune cells in the retina and play a key role in the pathogenesis of retinitis pigmentosa (RP). Many previous studies on the roles of microglia mainly focused on the neurotoxicity or neuroprotection of photoreceptors, while their contributions to synaptic remodeling of neuronal circuits in the retina of early RP remained unclarified. In the present study, we used Royal College of Surgeons (RCS) rats, a classic RP model characterized by progressive microglia activation and synapse loss, to investigate the constitutive effects of microglia on the synaptic lesions and ectopic neuritogenesis.

Changes in intrinsic excitability of ganglion cells in degenerated retinas of RCS rats.

Aim: To evaluate the intrinsic excitability of retinal ganglion cells (RGCs) in degenerated retinas.

Methods: The intrinsic excitability of various morphologically defined RGC types using a combination of patch-clamp recording and the Lucifer yellow tracer in retinal whole-mount preparations harvested from Royal College of Surgeons (RCS) rats, a common retinitis pigmentosa (RP) model, in a relatively late stage of retinal degeneration (P90) were investigated. Several parameters of RGC morphologies and action potentials (APs) were measured and compared to those of non-dystrophic control rats, including dendritic stratification, dendritic field diameter, peak amplitude, half width, resting membrane potential, AP threshold, depolarization to threshold, and firing rates.

Proteomic profiling of early degenerative retina of RCS rats.

Aim: To identify the underlying cellular and molecular changes in retinitis pigmentosa (RP).

Methods: Label-free quantification-based proteomics analysis, with its advantages of being more economic and consisting of simpler procedures, has been used with increasing frequency in modern biological research. Dystrophic RCS rats, the first laboratory animal model for the study of RP, possess a similar pathological course as human beings with the diseases.

Homeostatic Plasticity Mediated by Rod-Cone Gap Junction Coupling in Retinal Degenerative Dystrophic RCS Rats.

Rod-cone gap junctions open at night to allow rod signals to pass to cones and activate the cone-bipolar pathway. This enhances the ability to detect large, dim objects at night. This electrical synaptic switch is governed by the circadian clock and represents a novel form of homeostatic plasticity that regulates retinal excitability according to network activity.

Functional ectopic neuritogenesis by retinal rod bipolar cells is regulated by miR-125b-5p during retinal remodeling in RCS rats.

Following retinal degeneration, retinal remodeling can cause neuronal microcircuits to undergo structural alterations, which particularly affect the dendrites of bipolar cells. However, the mechanisms and functional consequences of such changes remain unclear. Here, we used Royal College of Surgeon (RCS) rats as a model of retinal degeneration, to study structural changes in rod bipolar cells (RBCs) and the underlying mechanisms of these changes.

Human melanopsin-AAV2/8 transfection to retina transiently restores visual function in rd1 mice.

Aim: To explore whether ectopic expression of human melanopsin can effectively and safely restore visual function in rd1 mice.

Methods: Hematoxylin-eosin staining of retinal sections from rd1 mice was used to detect the thickness of the outer nuclear layer to determine the timing of surgery. We constructed a human melanopsin-AAV2/8 viral vector and injected it into the subretinal space of rd1 mice.

Connexin-based channels contribute to metabolic pathways in the oligodendroglial lineage.

Oligodendrocyte precursor cells (OPCs) undergo a series of energy-consuming developmental events; however, the uptake and trafficking pathways for their energy metabolites remain unknown. In the present study, we found that 2-NBDG, a fluorescent glucose analog, can be delivered between astrocytes and oligodendrocytes through connexin-based gap junction channels but cannot be transferred between astrocytes and OPCs. Instead, connexin hemichannel-mediated glucose uptake supports OPC proliferation, and ethidium bromide uptake or increase of 2-NBDG uptake rate is correlated with intracellular Ca(2+) elevation in OPCs, indicating a Ca(2+)-dependent activation of connexin hemichannels.

Synaptic vesicles are "primed" for fast clathrin-mediated endocytosis at the ribbon synapse.

Retrieval of synaptic vesicles can occur 1-10 s after fusion, but the role of clathrin during this process has been unclear because the classical mode of clathrin-mediated endocytosis (CME) is an order of magnitude slower, as during retrieval of surface receptors. Classical CME is thought to be rate-limited by the recruitment of clathrin, which raises the question: how is clathrin recruited during synaptic vesicle recycling? To investigate this question we applied total internal reflection fluorescence microscopy (TIRFM) to the synaptic terminal of retinal bipolar cells expressing fluorescent constructs of clathrin light-chain A. Upon calcium influx we observed a fast accumulation of clathrin within 100 ms at the periphery of the active zone.

Extracellular vesicles from neural stem cells transfer IFN-γ via Ifngr1 to activate Stat1 signaling in target cells.

The idea that stem cell therapies work only via cell replacement is challenged by the observation of consistent intercellular molecule exchange between the graft and the host. Here we defined a mechanism of cellular signaling by which neural stem/precursor cells (NPCs) communicate with the microenvironment via extracellular vesicles (EVs), and we elucidated its molecular signature and function. We observed cytokine-regulated pathways that sort proteins and mRNAs into EVs.

Expression of perineuronal nets, parvalbumin and protein tyrosine phosphatase σ in the rat visual cortex during development and after BFD.

Unlabelled: Abstract Purpose of the Study: Protein tyrosine phosphatase σ (PTPσ) acts as a neuronal receptor for chondroitin sulfate proteoglycans (CSPGs). CSPGs have inhibitory effects on experience-dependent plasticity and usually form lattice-like cell coatings that surround the parvalbumin (PV) interneurons in the visual cortex (VC). We investigated developmental changes and the effect of binocular form deprivation (BFD) on PTPσ, perineuronal nets (PNNs) and their tempo-spatial relationships with PV neurons in the VC.

Homeostatic synaptic plasticity through changes in presynaptic calcium influx.

Chronic perturbations of electrical activity within neural circuits lead to compensatory changes in synaptic strength collectively termed homeostatic synaptic plasticity. The postsynaptic mechanisms underlying these modifications have been characterized in some detail, but the presynaptic mechanisms that alter the efficiency of evoked neurotransmitter release are less clear. To investigate the role of presynaptic calcium influx, we have combined the use of two fluorescent proteins in cultured hippocampal neurons: a calcium reporter localized to synaptic vesicles, SyGCaMP2, and a reporter of vesicle fusion, SypHy.

Nicotine-induced Ca2+-myristoyl switch of neuronal Ca2+ sensor VILIP-1 in hippocampal neurons: a possible crosstalk mechanism for nicotinic receptors.

Visinin-like protein (VILIP-1) belongs to the neuronal Ca2+ sensor family of EF-hand Ca2+-binding proteins that regulate a variety of Ca2+-dependent signal transduction processes in neurons. It is an interaction partner of alpha4beta2 nicotinic acetylcholine receptor (nAChR) and increases surface expression level and agonist sensitivity of the receptor in oocytes. Nicotine stimulation of nicotinic receptors has been reported to lead to an increase in intracellular Ca2+ concentration by Ca2+-permeable nAChRs, which in turn might lead to activation of VILIP-1, by a mechanism described as the Ca2+-myristoyl switch.

Implication of neuronal Ca2+ -sensor protein VILIP-1 in the glutamate hypothesis of schizophrenia.

Post mortem studies in the hippocampus of schizophrenia patients revealed increased expression of neuronal Ca(2+)-sensor VILIP-1 (visinin-like protein) and enhanced co-localization with alpha4beta2 nAChR in interneurons. To study the pathological role of VILIP-1, particularly in interneurons, in the context of the glutamate hypothesis of schizophrenia, we have used ketamine-treated rats, a NMDA receptor hypofunction model, and hippocampal cultures as model systems for schizophrenia. Treatment with ketamine leads to enhanced VILIP-1 expression in interneurons in rat hippocampal CA1 region.

Proteome analysis of up-regulated proteins in the rat spinal cord induced by transection injury.

The inability of the CNS to regenerate in adult mammals propels us to reveal associated proteins involved in the injured CNS. In this paper, either thoracic laminectomy (as sham control) or thoracic spinal cord transection was performed on male adult rats. Five days after surgery, the whole spinal cord tissue was dissected and fractionated into water-soluble (dissolved in Tris buffer) and water-insoluble (dissolved in a solution containing chaotropes and surfactants) portions for 2-DE.

Cellular and subcellular localization of the inhibitory glycine receptor in hippocampal neurons.

Inhibitory glycine receptors are most abundant in spinal cord and brainstem, and glycinergic synapses have a well-established role in the regulation of locomotor behavior. Little is known about the function of glycine receptors in cortex and hippocampus, where GABA plays a dominant role in synaptic inhibition. Therefore, we have investigated tissue and cellular expression of glycine receptor alpha-subunits.

Expression analysis of members of the neuronal calcium sensor protein family: combining bioinformatics and Western blot analysis.

We have used in silico mining of public databases (NCBI UniGene and NCI SAGE Anatomic Viewer) as a tool to obtain the tissue distribution pattern of three members of the neuronal calcium sensor protein family, namely VILIP-1, hippocalcin, and NCS-1 in humans. The theoretical human mRNA expression profile of the calcium sensor proteins derived from expressed sequence tag (EST) and serial analysis of gene expression (SAGE) data was compared with expression data from human tissues obtained by Western blot analysis. Since the EST databank searches do not yet give comparable results for rat which is often used as model animal, we have also analyzed the protein expression in rat tissues.