Neuronal calcium sensor proteins: generating diversity in neuronal Ca2+ signalling

Progressive Elevation of Store-Operated Calcium Entry-Associated Regulatory Factor (SARAF) and Calcium Pathway Dysregulation in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic autoimmune disorder characterized by demyelination and neuronal damage in the central nervous system. Dysregulation of calcium homeostasis, particularly through the Store-Operated Calcium Entry-Associated Regulatory Factor (SARAF), has been implicated in MS pathogenesis. This study investigated SARAF, STIM1, and Orai1 expression patterns and their relationship to calcium homeostasis in 45 Bahraini MS patients and 45 matched healthy controls using ELISA and real-time PCR analyses. MS patients showed significantly elevated serum SARAF levels in both early (192.26 ± 47.00 pg/mL) and late MS stages (341.47 ± 96.19 pg/mL) compared to controls (129.82 ± 30.82 pg/mL; p < 0.001. SARAF expressions were markedly increased in MS patients (3.829 ± 0.04422 vs. 1 ± 0; p < 0.0001), while STIM1 (0.4324 ± 0.01471) and ORAI1 (0.2963 ± 0.02156) expressions were significantly reduced compared to the controls (p < 0.0001). Intracellular calcium levels were notably elevated in both early and late MS stages. These findings suggest that the progressive elevation of SARAF, coupled with altered STIM1 and ORAI1 expression, may serve as potential biomarkers for MS progression and represent promising therapeutic targets.

Interactions of Li+ ions with NCS1: A potential mechanism of Li+ neuroprotective action against psychotic disorders

Li+ based drugs have been used for the treatment of psychiatric disorders due to their mood stabilizing role for decades. Recently, several studies reported the protective effect of Li+ against severe neuropathologies such as Parkinson's, Alzheimer's, and Huntington's disease. Surprisingly, despite a broad range of Li+ effects on neurological conditions, little is known about its molecular mechanism. In this study, we propose that neuronal calcium sensor 1 (NCS1), can be an effective molecular target for Li+ action. Here we show that the EF-hands in ApoNCS1 have submillimolar affinity for Li+ with Kd = 223 ± 19 μM. Li+ binding to ApoNCS1 quenches Trp emission intensity, suggesting distinct Trp sidechains environment in Li+NCS1 compared to ApoNCS1 and Ca2+NCS1. Li+ association also stabilizes the protein α-helical structure, in a similar way to Ca2+. Li+ association does not promote NCS1 dimerization. Association of Li+ increases NCS1 affinity for the D2R receptor binding peptide, in a similar way to Ca2+, however, the affinity of NCS1 for chlorpromazine is reduced with respect to Ca2+NCS1, possibly due to a decrease in solvent exposed hydrophobic area on the NCS1 surface in the presence of Li+. MD simulation data suggests that Li+ ions are coordinated by four oxygens from Asp and Glu sidechains and one carbonyl oxygen, in a similar way as reported previously for Li+ binding to DREAM. Overall, the data shows that Li+ binds to EF-hands of NCS1 and Li+NCS1 interactions may be involved in the potential neuroprotective role of Li+ against psychotic disorders.

Synapse Neurotransmitter Channel-Inspired AlOx Memristor with "V" Type Oxygen Vacancy Distribution

Memristor possesses great potential and advantages in neuromorphic computing, while consistency and power consumption issues have been hindering its commercialization. Low cost and accuracy are the advantages of human brain, so memristors can be used to construct brain-like synaptic devices to solve these problems. In this work, a five-layer AlOx device with a V-shaped oxygen distribution is used to simulate biological synapses. The device simulates synapse structurally. Further, under electrical stimulation, O2- moves to the Ti electrode and oxygen vacancy (Vo) moves to the Pt electrode, thus forming a conductive filament (CF), which simulates the Ca2+ flow and releases neurotransmitters to the postsynaptic membrane, thus realizing the transmission of information. By controlling applied voltage, the regulation of Ca2+ gated pathway is realized to control the Ca2+ internal flow and achieve different degrees of information transmission. Long-term Potentiation (LTP)/Long-term Depression (LTD), Spike Timing Dependent Plasticity (STDP), these basic synaptic performances can be simulated. The AlOx device realizes low power consumption (56.7 pJ/392 fJ), high switching speed (25 ns/60 ns), and by adjusting the window value, the nonlinearity is improved (0.133/0.084), a high recognition accuracy (98.18%) is obtained in neuromorphic simulation. It shows a great prospect in multi-value storage and neuromorphic computing.

Stress survival and longevity of Caenorhabditis elegans lacking NCS-1

Although dysfunctional Ca2+ signaling can trigger biochemical reactions that lead to cell death, the role of calcium-binding proteins (CBPs) in this process is still a topic of debate. Neuronal calcium sensor 1 (NCS-1) is a CBP that is highly conserved and has been shown to increase cell survival against various types of injuries. As such, we hypothesized that NCS-1 could also be a stress-responsive protein with potential effects on survival and longevity. To explore this possibility, we conducted experiments to examine how Caenorhabditis elegans ncs-1 mutant nematodes fared under three different stress conditions: hyperosmotic, thermal, and chemical oxidant challenges. Our results showed that while the lack of NCS-1 had no effect on survival responses to hyperosmotic and thermal stresses, ncs-1 worms demonstrated remarkable resistance to the oxidant paraquat in a dose-dependent manner. Based on these findings, we conclude that C. elegans may employ adaptive mechanisms in the absence of NCS-1 to survive specific oxidative stress stimuli.

Force versus Response: Methods for Activating and Characterizing Mechanosensitive Ion Channels and GPCRs

Mechanotransduction is the process whereby cells convert mechanical signals into electrochemical responses, where mechanosensitive proteins mediate this interaction. To characterize these critical proteins, numerous techniques have been developed that apply forces and measure the subsequent cellular responses. While these approaches have given insight into specific aspects of many such proteins, subsequent validation and cross-comparison between techniques remain difficult given significant variations in reported activation thresholds and responses for the same protein across different studies. Accurately determining mechanosensitivity responses for various proteins, however, is essential for understanding mechanotransduction and potential physiological implications, including therapeutics. This critical review provides an assessment of current and emerging approaches used for mechanosensitive ion channel and G-Coupled Receptors (GPCRs) stimulation and measurement, with a specific focus on the ability to quantitatively measure mechanosensitive responses.

Exploring the role of mitochondrial uncoupling protein 4 in brain metabolism: implications for Alzheimer's disease

The brain's high demand for energy necessitates tightly regulated metabolic pathways to sustain physiological activity. Glucose, the primary energy substrate, undergoes complex metabolic transformations, with mitochondria playing a central role in ATP production via oxidative phosphorylation. Dysregulation of this metabolic interplay is implicated in Alzheimer's disease (AD), where compromised glucose metabolism, oxidative stress, and mitochondrial dysfunction contribute to disease progression. This review explores the intricate bioenergetic crosstalk between astrocytes and neurons, highlighting the function of mitochondrial uncoupling proteins (UCPs), particularly UCP4, as important regulators of brain metabolism and neuronal function. Predominantly expressed in the brain, UCP4 reduces the membrane potential in the inner mitochondrial membrane, thereby potentially decreasing the generation of reactive oxygen species. Furthermore, UCP4 mitigates mitochondrial calcium overload and sustains cellular ATP levels through a metabolic shift from mitochondrial respiration to glycolysis. Interestingly, the levels of the neuronal UCPs, UCP2, 4 and 5 are significantly reduced in AD brain tissue and a specific UCP4 variant has been associated to an increased risk of developing AD. Few studies modulating the expression of UCP4 in astrocytes or neurons have highlighted protective effects against neurodegeneration and aging, suggesting that pharmacological strategies aimed at activating UCPs, such as protonophoric uncouplers, hold promise for therapeutic interventions in AD and other neurodegenerative diseases. Despite significant advances, our understanding of UCPs in brain metabolism remains in its early stages, emphasizing the need for further research to unravel their biological functions in the brain and their therapeutic potential.

Calcium-Mediated Cell Adhesion Enhancement-Based Antimetastasis and Synergistic Antitumor Therapy by Conjugated Polymer-Calcium Composite Nanoparticles

Strengthening tumor cellular adhesion through regulating the concentration of extracellular Ca2+ is highly challenging and promising for antimetastasis. Herein, a pH-responsive conjugated polymer-calcium composite nanoparticle (PFV/CaCO3/PDA@PEG) is developed for calcium-mediated cell adhesion enhancement-based antimetastasis and reactive oxygen species (ROS)-triggered calcium overload and photodynamic therapy (PDT) synergistic tumor treatment. PFV/CaCO3/PDA@PEG is mainly equipped with conjugated poly(fluorene-co-vinylene) (PFV-COOH)-composited CaCO3 nanoparticles, which can be rapidly decomposed under the tumor acidic microenvironment, effectively releasing Ca2+ and the photosensitizer PFV-COOH. The high extracellular Ca2+ concentration facilitates the generation of dimers between two adjacent cadherin ectodomains, which greatly enhances cell-cell adhesion and suppresses tumor metastasis. The inhibition rates are 97 and 87% for highly metastatic tumor cells 4T1 and MCF-7, respectively. Such a well-designed nanoparticle also contributes to realizing PDT, mitochondrial dysfunction, and ROS-triggered Ca2+ overload synergistic therapy. Furthermore, PFV/CaCO3/PDA@PEG displayed superior in vivo inhibition of 4T1 tumor growth and demonstrated a marked antimetastatic effect by both intravenous and intratumoral injection modes. Thus, this study provides a powerful strategy for calcium-mediated metastasis inhibition for tumor therapy.

Monitoring GPCR conformation with GFP-inspired dyes

Solvatochromic compounds have emerged as valuable environment-sensitive probes for biological research. Here we used thiol-reactive solvatochromic analogs of the green fluorescent protein (GFP) chromophore to track conformational changes in two proteins, recoverin and the A2A adenosine receptor (A2AAR). Two dyes showed Ca2+-induced fluorescence changes when attached to recoverin. Our best-performing dye, DyeC, exhibited agonist-induced changes in both intensity and shape of its fluorescence spectrum when attached to A2AAR; none of these effects were observed with other common environment-sensitive dyes. Molecular dynamics simulations showed that activation of the A2AAR led to a more confined and hydrophilic environment for DyeC. Additionally, an allosteric modulator of A2AAR induced distinct fluorescence changes in the DyeC spectrum, indicating a unique receptor conformation. Our study demonstrated that GFP-inspired dyes are effective for detecting structural changes in G protein-coupled receptors (GPCRs), offering advantages such as intensity-based and ratiometric tracking, redshifted fluorescence spectra, and sensitivity to allosteric modulation.

Triboiontronics with temporal control of electrical double layer formation

The nanoscale electrical double layer plays a crucial role in macroscopic ion adsorption and reaction kinetics. In this study, we achieve controllable ion migration by dynamically regulating asymmetric electrical double layer formation. This tailors the ionic-electronic coupling interface, leading to the development of triboiontronics. Controlling the charge-collecting layer coverage on dielectric substrates allows for charge collection and adjustment of the substrate-liquid contact electrification property. By dynamically managing the asymmetric electrical double layer formation between the dielectric substrate and liquids, we develop a direct-current triboiontronic nanogenerator. This nanogenerator produces a transferred charge density of 412.54 mC/m2, significantly exceeding that of current hydrovoltaic technology and conventional triboelectric nanogenerators. Additionally, incorporating redox reactions to the process enhances the peak power and transferred charge density to 38.64 W/m2 and 540.70 mC/m2, respectively.

Disease-modifying rdHSV-CA8* non-opioid analgesic gene therapy treats chronic osteoarthritis pain by activating Kv7 voltage-gated potassium channels

Chronic pain is common in our population, and most of these patients are inadequately treated, making the development of safer analgesics a high priority. Knee osteoarthritis (OA) is a primary cause of chronic pain and disability worldwide, and lower extremity OA is a major contributor to loss of quality-adjusted life-years. In this study we tested the hypothesis that a novel JDNI8 replication-defective herpes simplex-1 viral vector (rdHSV) incorporating a modified carbonic anhydrase-8 transgene (CA8*) produces analgesia and treats monoiodoacetate-induced (MIA) chronic knee pain due to OA. We observed transduction of lumbar DRG sensory neurons with these viral constructs (vHCA8*) (~40% of advillin-positive cells and ~ 50% of TrkA-positive cells colocalized with V5-positive cells) using the intra-articular (IA) knee joint (KJ) route of administration. vHCA8* inhibited chronic mechanical OA knee pain induced by MIA was dose- and time-dependent. Mechanical thresholds returned to Baseline by D17 after IA KJ vHCA8* treatment, and exceeded Baseline (analgesia) through D65, whereas negative controls failed to reach Baseline responses. Weight-bearing and automated voluntary wheel running were improved by vHCA8*, but not negative controls. Kv7 voltage-gated potassium channel-specific inhibitor XE-991 reversed vHCA8*-induced analgesia. Using IHC, IA KJ of vHCA8* activated DRG Kv7 channels via dephosphorylation, but negative controls failed to impact Kv7 channels. XE-991 stimulated Kv7.2-7.5 and Kv7.3 phosphorylation using western blotting of differentiated SH-SY5Y cells, which was inhibited by vHCA8* but not by negative controls. The observed prolonged dose-dependent therapeutic effects of IA KJ administration of vHCA8* on MIA-induced chronic KJ pain due to OA is consistent with the specific activation of Kv7 channels in small DRG sensory neurons. Together, these data demonstrate for the first-time local IA KJ administration of vHCA8* produces opioid-independent analgesia in this MIA-induced OA chronic pain model, supporting further therapeutic development.

Different recovery patterns of the surviving bivalve Mytilus galloprovincialis based on transcriptome profiling exposed to spherical or fibrous polyethylene microplastics

Microplastics (MPs) are pervasive pollutants exuded from anthropogenic activities and ingested by animals in different ecosystems. This transcriptomic profiling study aimed to explore the impact of polyethylene MPs on Mytilus galloprovincialis, an ecologically significant bivalve species. The toxicity of two MPs types was found to result in increased cellular stress when exposed up to 14 days. Moreover, recovery mechanisms were also observed in progress. Mussels exhibited different gene expression patterns and molecular regulation in response to cellular reactive oxygen species (ROS) stress. The transcriptome analysis demonstrated a notable hindrance in cilia movement as MPs ingested through gills. Subsequent entry resulted in a significant disruption in the cytoskeletal organization, cellular projection, and cilia beat frequency. On day 4 (D4), signal transduction and activation of apoptosis evidenced the signs of toxic consequences. Mussels exposed to spherical MPs shown significant recovery on day 14 (D14), characterized by the upregulation of anti-apoptotic genes and antioxidant genes. The expression of P53 and BCL2 genes was pivotal in controlling the apoptotic process and promoting cell survival. Mussels exposed to fibrous MPs displayed a delayed cell survival effect. However, the elevated physiological stress due to fibrous MPs resulted in energy transfer by compensatory regulation of metabolic processes to expedite cellular recovery. These observations highlighted the intricate and varied reaction of cell survival mechanisms in mussels to recover toxicity. This study provides critical evidence of the ecotoxicological impacts of two different MPs and emphasizes the environmental risks they pose to aquatic ecosystems. Our conclusion highlights the detrimental effects of MPs on M. galloprovincialis and the need for more stringent regulations to protect marine ecosystems.

rdHSV-CA8 non-opioid analgesic gene therapy decreases somatosensory neuronal excitability by activating Kv7 voltage-gated potassium channels

Chronic pain is common and inadequately treated, making the development of safe and effective analgesics a high priority. Our previous data indicate that carbonic anhydrase-8 (CA8) expression in dorsal root ganglia (DRG) mediates analgesia via inhibition of neuronal ER inositol trisphosphate receptor-1 (ITPR1) via subsequent decrease in ER calcium release and reduction of cytoplasmic free calcium, essential to the regulation of neuronal excitability. This study tested the hypothesis that novel JDNI8 replication-defective herpes simplex-1 viral vectors (rdHSV) carrying a CA8 transgene (vHCA8) reduce primary afferent neuronal excitability. Whole-cell current clamp recordings in small DRG neurons showed that vHCA8 transduction caused prolongation of their afterhyperpolarization (AHP), an essential regulator of neuronal excitability. This AHP prolongation was completely reversed by the specific Kv7 channel inhibitor XE-991. Voltage clamp recordings indicate an effect via Kv7 channels in vHCA8-infected small DRG neurons. These data demonstrate for the first time that vHCA8 produces Kv7 channel activation, which decreases neuronal excitability in nociceptors. This suppression of excitability may translate in vivo as non-opioid dependent behavioral- or clinical analgesia, if proven behaviorally and clinically.

The Calmodulin-interacting peptide Pcp4a regulates feeding state-dependent behavioral choice in zebrafish

Animals constantly need to judge the valence of an object in their environment: is it potential food or a threat? The brain makes fundamental decisions on the appropriate behavioral strategy by integrating external information from sensory organs and internal signals related to physiological needs. For example, a hungry animal may take more risks than a satiated one when deciding to approach or avoid an object. Using a proteomic profiling approach, we identified the Calmodulin-interacting peptide Pcp4a as a key regulator of foraging-related decisions. Food intake reduced abundance of protein and mRNA of pcp4a via dopamine D2-like receptor-mediated repression of adenylate cyclase. Accordingly, deleting the pcp4a gene made zebrafish larvae more risk averse in a binary decision assay. Strikingly, neurons in the tectum became less responsive to prey-like visual stimuli in pcp4a mutants, thus biasing the behavior toward avoidance. This study pinpoints a molecular mechanism modulating behavioral choice according to internal state.

Calcium-Associated Proteins in Neuroregeneration

The dysregulation of intracellular calcium levels is a critical factor in neurodegeneration, leading to the aberrant activation of calcium-dependent processes and, ultimately, cell death. Ca2+ signals vary in magnitude, duration, and the type of neuron affected. A moderate Ca2+ concentration can initiate certain cellular repair pathways and promote neuroregeneration. While the peripheral nervous system exhibits an intrinsic regenerative capability, the central nervous system has limited self-repair potential. There is evidence that significant variations exist in evoked calcium responses and axonal regeneration among neurons, and individual differences in regenerative capacity are apparent even within the same type of neurons. Furthermore, some studies have shown that neuronal activity could serve as a potent regulator of this process. The spatio-temporal patterns of calcium dynamics are intricately controlled by a variety of proteins, including channels, ion pumps, enzymes, and various calcium-binding proteins, each of which can exert either positive or negative effects on neural repair, depending on the cellular context. In this concise review, we focus on several calcium-associated proteins such as CaM kinase II, GAP-43, oncomodulin, caldendrin, calneuron, and NCS-1 in order to elaborate on their roles in the intrinsic mechanisms governing neuronal regeneration following traumatic damage processes.

All-potassium channel CRISPR screening reveals a lysine-specific pathway of insulin secretion

OBJECTIVE

Genome-scale CRISPR-Cas9 knockout coupled with single-cell RNA sequencing (scRNA-seq) has been used to identify function-related genes. However, this method may knock out too many genes, leading to low efficiency in finding genes of interest. Insulin secretion is controlled by several electrophysiological events, including fluxes of KATP depolarization and K+ repolarization. It is well known that glucose stimulates insulin secretion from pancreatic β-cells, mainly via the KATP depolarization channel, but whether other nutrients directly regulate the repolarization K+ channel to promote insulin secretion is unknown.

METHODS

We used a system involving CRISPR-Cas9-mediated knockout of all 83 K+ channels and scRNA-seq in a pancreatic β cell line to identify genes associated with insulin secretion.

RESULTS

The expression levels of insulin genes were significantly increased after all-K+ channel knockout. Furthermore, Kcnb1 and Kcnh6 were the two most important repolarization K+ channels for the increase in high-glucose-dependent insulin secretion that occurred upon application of specific inhibitors of the channels. Kcnh6 currents, but not Kcnb1 currents, were reduced by one of the amino acids, lysine, in both transfected cells, primary cells and mice with β-cell-specific deletion of Kcnh6.

CONCLUSIONS

Our function-related CRISPR screen with scRNA-seq identifies Kcnh6 as a lysine-specific channel.

Calmodulin: a highly conserved and ubiquitous Ca2+ sensor

Calcium ions (Ca2+) play critical roles in various biological phenomena. The free Ca2+ concentration in the cytoplasm of a resting cell is at the 10-7 M level, whereas that outside the cell is 10-3 M, creating a 10,000-fold gradient of Ca2+ concentrations across the cell membrane, separating the intracellular and extracellular solutions.1),2) When a cell is activated by external stimuli, the intracellular Ca2+ concentration increases to levels of 10-6-10-5 M through Ca2+ entry from the extracellular solution via plasma membrane Ca2+ channels and/or Ca2+ release from intracellular stores. This transient increase in Ca2+ functions as an important signal mediated by Ca2+ sensors. Thus, Ca2+ signals are transmitted to intracellular loci such as distinct, localized targets of Ca2+ sensors. Among numerous Ca2+ sensors present in cells, calmodulin is a highly conserved and ubiquitous Ca2+ sensor.3).

Feedforward and feedback mechanisms cooperatively regulate rapid experience-dependent response adaptation in a single thermosensory neuron type

Sensory adaptation allows neurons to adjust their sensitivity and responses based on recent experience. The mechanisms that mediate continuous adaptation to stimulus history over seconds to hours long timescales, and whether these mechanisms can operate within a single sensory neuron type, are unclear. The single pair of AFD thermosensory neurons in C. elegans exhibits experience-dependent plasticity in their temperature response thresholds on both minutes- and hours-long timescales upon a temperature upshift. While long-term response adaptation requires changes in gene expression in AFD, the mechanisms driving rapid response plasticity are unknown. Here, we show that rapid thermosensory response adaptation in AFD is mediated via cGMP and calcium-dependent feedforward and feedback mechanisms operating at the level of primary thermotransduction. We find that either of two thermosensor receptor guanylyl cyclases (rGCs) alone is sufficient to drive rapid adaptation, but that each rGC drives adaptation at different rates. rGC-driven adaptation is mediated in part via phosphorylation of their intracellular domains, and calcium-dependent feedback regulation of basal cGMP levels via a neuronal calcium sensor protein. In turn, cGMP levels feedforward via cGMP-dependent protein kinases to phosphorylate a specific subunit of the cGMP-gated thermotransduction channel to further regulate rapid adaptation. Our results identify multiple molecular pathways that act in AFD to ensure rapid adaptation to a temperature change, and indicate that the deployment of both transcriptional and non-transcriptional mechanisms within a single sensory neuron type can contribute to continuous sensory adaptation.

Generation of an NCS1 gene knockout human induced pluripotent stem cell line using CRISPR/Cas9

NCS1 (Neuronal calcium sensor protein 1) encodes a highly conserved calcium binding protein abundantly expressed in neurons. It modulates intracellular calcium homeostasis, calcium-dependent signaling pathways as well as neuronal transmission and plasticity. Here, we generated a NCS1 knockout human induced pluripotent stem cell (hiPSC) line using CRISPR-Cas9 genome editing. It shows regular expression of pluripotent markers, normal iPSC morphology and karyotype as well as no detectable off-target effects on top 6 potentially affected genes. This newly generated cell line constitutes a valuable tool for studying the role of NCS1 in the pathophysiology of various neuropsychiatric disorders and non-neurological disease.

Different effects of CYP27A1 and CYP7B1 on cognitive function: Two mouse models in comparison

The oxysterol 27-hydroxycholesterol (27OHC) is produced by the enzyme sterol 27-hydroxylase (Cyp27A1) and is mainly catabolized to 7α-Hydroxy-3-oxo-4-cholestenoic acid (7-HOCA) by the enzyme cytochrome P-450 oxysterol 7α-hydroxylase (Cyp7B1). 27OHC is mostly produced in the liver and can reach the brain by crossing the blood-brain barrier. A large body of evidence shows that CYP27A1 overexpression and high levels of 27OHC have a detrimental effect on the brain, causing cognitive and synaptic dysfunction together with a decrease in glucose uptake in mice. In this work, we analyzed two mouse models with high levels of 27OHC: Cyp7B1 knock-out mice and CYP27A1 overexpressing mice. Despite the accumulation of 27OHC in both models, Cyp7B1 knock-out mice maintained intact learning and memory capacities, neuronal morphology, and brain glucose uptake over time. Neurons treated with the Cyp7B1 metabolite 7-HOCA did not show changes in synaptic genes and 27OHC-treated Cyp7B1 knock-out neurons could not counteract 27OHC detrimental effects. This suggests that 7-HOCA and Cyp7B1 deletion in neurons do not mediate the neuroprotective effects observed in Cyp7B1 knock-out animals. RNA-seq of neuronal nuclei sorted from Cyp7B1 knock-out brains revealed upregulation of genes likely to confer neuroprotection to these animals. Differently from Cyp7B1 knock-out mice, transcriptomic data from CYP27A1 overexpressing neurons showed significant downregulation of genes associated with synaptic function and several metabolic processes. Our results suggest that the differences observed in the two models may be mediated by the higher levels of Cyp7B1 substrates such as 25-hydroxycholesterol and 3β-Adiol in the knock-out mice and that CYP27A1 overexpressing mice may be a more suitable model for studying 27-OHC-specific signaling. We believe that future studies on Cyp7B1 and Cyp27A1 will contribute to a better understanding of the pathogenic mechanisms of neurodegenerative diseases like Alzheimer's disease and may lead to potential new therapeutic approaches.

Electrochemical-Memristor-Based Artificial Neurons and Synapses-Fundamentals, Applications, and Challenges

Artificial neurons and synapses are considered essential for the progress of the future brain-inspired computing, based on beyond von Neumann architectures. Here, a discussion on the common electrochemical fundamentals of biological and artificial cells is provided, focusing on their similarities with the redox-based memristive devices. The driving forces behind the functionalities and the ways to control them by an electrochemical-materials approach are presented. Factors such as the chemical symmetry of the electrodes, doping of the solid electrolyte, concentration gradients, and excess surface energy are discussed as essential to understand, predict, and design artificial neurons and synapses. A variety of two- and three-terminal memristive devices and memristive architectures are presented and their application for solving various problems is shown. The work provides an overview of the current understandings on the complex processes of neural signal generation and transmission in both biological and artificial cells and presents the state-of-the-art applications, including signal transmission between biological and artificial cells. This example is showcasing the possibility for creating bioelectronic interfaces and integrating artificial circuits in biological systems. Prospectives and challenges of the modern technology toward low-power, high-information-density circuits are highlighted.

Machine learning reveals common transcriptomic signatures across rat brain and placenta following developmental organophosphate ester exposure

Toxicogenomics is a critical area of inquiry for hazard identification and to identify both mechanisms of action and potential markers of exposure to toxic compounds. However, data generated by these experiments are highly dimensional and present challenges to standard statistical approaches, requiring strict correction for multiple comparisons. This stringency often fails to detect meaningful changes to low expression genes and/or eliminate genes with small but consistent changes particularly in tissues where slight changes in expression can have important functional differences, such as brain. Machine learning offers an alternative analytical approach for "omics" data that effectively sidesteps the challenges of analyzing highly dimensional data. Using 3 rat RNA transcriptome sets, we utilized an ensemble machine learning approach to predict developmental exposure to a mixture of organophosphate esters (OPEs) in brain (newborn cortex and day 10 hippocampus) and late gestation placenta of male and female rats, and identified genes that informed predictor performance. OPE exposure had sex specific effects on hippocampal transcriptome, and significantly impacted genes associated with mitochondrial transcriptional regulation and cation transport in females, including voltage-gated potassium and calcium channels and subunits. To establish if this holds for other tissues, RNAseq data from cortex and placenta, both previously published and analyzed via a more traditional pipeline, were reanalyzed with the ensemble machine learning methodology. Significant enrichment for pathways of oxidative phosphorylation and electron transport chain was found, suggesting a transcriptomic signature of OPE exposure impacting mitochondrial metabolism across tissue types and developmental epoch. Here we show how machine learning can complement more traditional analytical approaches to identify vulnerable "signature" pathways disrupted by chemical exposures and biomarkers of exposure.

Interaction of calcium responsive proteins and transcriptional factors with the PHO regulon in yeasts and fungi

Phosphate and calcium ions are nutrients that play key roles in growth, differentiation and the production of bioactive secondary metabolites in filamentous fungi. Phosphate concentration regulates the biosynthesis of hundreds of fungal metabolites. The central mechanisms of phosphate transport and regulation, mediated by the master Pho4 transcriptional factor are known, but many aspects of the control of gene expression need further research. High ATP concentration in the cells leads to inositol pyrophosphate molecules formation, such as IP3 and IP7, that act as phosphorylation status reporters. Calcium ions are intracellular messengers in eukaryotic organisms and calcium homeostasis follows elaborated patterns in response to different nutritional and environmental factors, including cross-talking with phosphate concentrations. A large part of the intracellular calcium is stored in vacuoles and other organelles forming complexes with polyphosphate. The free cytosolic calcium concentration is maintained by transport from the external medium or by release from the store organelles through calcium permeable transient receptor potential (TRP) ion channels. Calcium ions, particularly the free cytosolic calcium levels, control the biosynthesis of fungal metabolites by two mechanisms, 1) direct interaction of calcium-bound calmodulin with antibiotic synthesizing enzymes, and 2) by the calmodulin-calcineurin signaling cascade. Control of very different secondary metabolites, including pathogenicity determinants, are mediated by calcium through the Crz1 factor. Several interactions between calcium homeostasis and phosphate have been demonstrated in the last decade: 1) The inositol pyrophosphate IP3 triggers the release of calcium ions from internal stores into the cytosol, 2) Expression of the high affinity phosphate transporter Pho89, a Na+/phosphate symporter, is controlled by Crz1. Also, mutants defective in the calcium permeable TRPCa7-like of Saccharomyces cerevisiae shown impaired expression of Pho89. This information suggests that CrzA and Pho89 play key roles in the interaction of phosphate and calcium regulatory pathways, 3) Finally, acidocalcisomes organelles have been found in mycorrhiza and in some melanin producing fungi that show similar characteristics as protozoa calcisomes. In these organelles there is a close interaction between orthophosphate, pyrophosphate and polyphosphate and calcium ions that are absorbed in the polyanionic polyphosphate matrix. These advances open new perspectives for the control of fungal metabolism.

Proteome Profiling of Rat Brain Cortical Changes during Early Postnatal Brain Development

Label-free quantitation (LFQ) was applied to proteome profiling of rat brain cortical development during the early postnatal period. Male and female rat brain extracts were prepared using a convenient, detergent-free sample preparation technique at postnatal days (PND) 2, 8, 15, and 22. The PND protein ratios were calculated using Proteome Discoverer, and the PND protein change profiles were constructed separately for male and female animals for key presynaptic, postsynaptic, and adhesion brain proteins. The profiles were compared to the analogous profiles assembled from the published mouse and rat cortex proteomic data, including the fractionated-synaptosome data. The PND protein-change trendlines, Pearson correlation coefficient (PCC), and linear regression analysis of the statistically significant PND protein changes were used in the comparative analysis of the datasets. The analysis identified similarities and differences between the datasets. Importantly, there were significant similarities in the comparison of the rat cortex PND (current work) vs mouse (previously published) PND profiles, although in general, a lower abundance of synaptic proteins in mice than in rats was found. The male and female rat cortex PND profiles were expectedly almost identical (98-99% correlation by PCC), which also substantiated this LFQ nanoflow liquid chromatography-high-resolution mass spectrometry approach.

Chemical shift assignments of retinal guanylyl cyclase activating protein 5 (GCAP5) with a mutation (R22A) that abolishes dimerization and enhances cyclase activation

Retinal membrane guanylyl cyclases (RetGCs) in vertebrate rod and cone photoreceptors are activated by a family of neuronal Ca2+ sensor proteins called guanylyl cyclase activating proteins (GCAP1-7). GCAP5 from zebrafish photoreceptors binds to RetGC and confers Ca2+/Fe2+-dependent regulation of RetGC enzymatic activity that promotes the recovery phase of visual phototransduction. We report NMR chemical shift assignments of GCAP5 with a R22A mutation (called GCAP5R22A) that abolishes protein dimerization and activates RetGC with 3-fold higher activity than that of wild type GCAP5 (BMRB No. 51,783).

Proton-Gated Synaptic Transistors, Based on an Electron-Beam Patterned Nafion Electrolyte

Neuromorphic processors using artificial neural networks are the center of attention for energy-efficient analog computing. Artificial synapses act as building blocks in such neural networks for parallel information processing and data storage. Herein we describe the fabrication of a proton-gated synaptic transistor using a Nafion electrolyte thin film, which is patterned by electron-beam lithography (EBL). The device has an active channel of indium-zinc-oxide (IZO) between the source and drain electrodes, which shows Ohmic behavior with a conductance level on the order of 100 μS. Under voltage applications to the gate electrode, the channel conductance is changed due to the injection and extraction of protons between the IZO channel and the Nafion electrolyte, emulating various synaptic functions with short-term and long-term plasticity. When positive (negative) gate voltage pulses are consecutively applied, the device exhibits long-term potentiation (depression) at the same number of steps as the number of input pulses. Based on these characteristics, an artificial neural network using this transistor shows ∼84% image recognition accuracy for handwritten digits. The subject transistor also successfully mimics paired-pulse facilitation and depression, Hebbian spike-timing-dependent plasticity, and Pavlovian associative learning followed by extinction activities. Finally, dynamical pattern image memorization is demonstrated in a 5 × 5 array of these synaptic transistors. The results indicate that EBL patternable Nafion electrolytes have great potential for use in the fabrication and circuit-level integration of synaptic devices for neuromorphic computing applications.

Targeting ovarian cancer stem cells: a new way out

Ovarian cancer (OC) is the most lethal gynecological malignancy due to tumor heterogeneity, the lack of reliable early diagnosis methods and the high incidence of chemoresistant recurrent disease. Although there are developments in chemotherapies and surgical techniques to improve the overall survival of OC patients, the 5-year survival of advanced OC patients is still low. To improve the prognosis of OC patients, it is important to search for novel therapeutic approaches. Cancer stem cells (CSCs) are a subpopulation of tumor cells that participate in tumor growth, metastasis and chemoresistance. It is important to study the role of CSCs in a highly heterogeneous disease such as OC, which may be significant to a better understanding of the oncogenetic and metastatic pathways of the disease and to develop novel strategies against its progression and platinum resistance. Here, we summarized the current findings about targeting methods against ovarian cancer stem cells, including related signaling pathways, markers and drugs, to better manage OC patients using CSC-based therapeutic strategies.

Neuronal Calcium Sensor-1 Protects Cortical Neurons from Hyperexcitation and Ca2+ Overload during Ischemia by Protecting the Population of GABAergic Neurons

A defection of blood circulation in the brain leads to ischemia, damage, and the death of nerve cells. It is known that individual populations of GABAergic neurons are the least resistant to the damaging factors of ischemia and therefore they die first of all, which leads to impaired inhibition in neuronal networks. To date, the neuroprotective properties of a number of calcium-binding proteins (calbindin, calretinin, and parvalbumin), which are markers of GABAergic neurons, are known. Neuronal calcium sensor-1 (NCS-1) is a signaling protein that is expressed in all types of neurons and is involved in the regulation of neurotransmission. The role of NCS-1 in the protection of neurons and especially their individual populations from ischemia and hyperexcitation has not been practically studied. In this work, using the methods of fluorescence microscopy, vitality tests, immunocytochemistry, and PCR analysis, the molecular mechanisms of the protective action of NCS-1 in ischemia/reoxygenation and hyperammonemia were established. Since NCS-1 is most expressed in GABAergic neurons, the knockdown of this protein with siRNA led to the most pronounced consequences in GABAergic neurons. The knockdown of NCS-1 (NCS-1-KD) suppressed the basic expression of protective proteins without significantly reducing cell viability. However, ischemia-like conditions (oxygen-glucose deprivation, OGD) and subsequent 24-h reoxygenation led to a more massive activation of apoptosis and necrosis in neurons with NCS-1-KD, compared to control cells. The mass death of NCS-1-KD cells during OGD and hyperammonemia has been associated with the induction of a more pronounced network hyperexcitation symptom, especially in the population of GABAergic neurons, leading to a global increase in cytosolic calcium ([Ca²⁺]_i). The symptom of hyperexcitation of neurons with NCS-1-KD correlated with a decrease in the level of expression of the calcium-binding protein-parvalbumin. This was accompanied by an increase in the expression of excitatory ionotropic glutamate receptors, N-methyl-D-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (NMDAR and AMPAR) against the background of suppression of the expression of glutamate decarboxylase (synthesis of γ-aminobutyric acid).

Neuronal calcium sensor 2 is key to moulting and oocyte development in the brown planthopper, Nilaparvata lugens

Intracellular calcium (Ca²⁺ ) is vital for signal transduction in many cellular events. Several Ca²⁺ -binding proteins mediate the transduction of intracellular calcium signals. The EF-hand motifs containing neuronal calcium sensor (NCS) proteins are mainly expressed in the nervous system, where they have important roles in the regulation of a variety of neuronal functions. NCS1 has four EF-hand motifs and well-defined neuronal development functions in a variety of eukaryotes. However, NCS2 has only been identified in invertebrates such as insects and nematodes thus far. The functions of NCS2 remain largely unknown. Here, we identified an orthologous NCS2 in the hemipteran Nilaparvata lugens. Based on qRT-PCR, this gene was found to be primarily expressed in the brain. Knockdown of NCS2 in each nymphal instar by RNA interference led to lethality and caused aggradation and disordered arrangement of lipid droplets in the ovaries and testes of adults, which were associated with the absence of mature oocytes in female ovaries and reduction of spermiation in male adults. Our findings revealed a novel function for NCS2 as a regulator in development and reproduction and suggested that this protein had an important role in modulating lipid droplet remodelling in ovary and testis of N. lugens adults.

Zinc Modulation of Neuronal Calcium Sensor Proteins: Three Modes of Interaction with Different Structural Outcomes

Neuronal calcium sensors (NCSs) are the family of EF-hand proteins mediating Ca²⁺-dependent signaling pathways in healthy neurons and neurodegenerative diseases. It was hypothesized that the calcium sensor activity of NCSs can be complemented by sensing fluctuation of intracellular zinc, which could further diversify their function. Here, using a set of biophysical techniques, we analyzed the Zn²⁺-binding properties of five proteins belonging to three different subgroups of the NCS family, namely, VILIP1 and neurocalcin-δ/NCLD (subgroup B), recoverin (subgroup C), as well as GCAP1 and GCAP2 (subgroup D). We demonstrate that each of these proteins is capable of coordinating Zn²⁺ with a different affinity, stoichiometry, and structural outcome. In the absence of calcium, recoverin and VILIP1 bind two zinc ions with submicromolar affinity, and the binding induces pronounced conformational changes and regulates the dimeric state of these proteins without significant destabilization of their structure. In the presence of calcium, recoverin binds zinc with slightly decreased affinity and moderate conformational outcome, whereas VILIP1 becomes insensitive to Zn²⁺. NCALD binds Zn²⁺ with micromolar affinity, but the binding induces dramatic destabilization and aggregation of the protein. In contrast, both GCAPs demonstrate low-affinity binding of zinc independent of calcium, remaining relatively stable even at submillimolar Zn²⁺ concentrations. Based on these data, and the results of structural bioinformatics analysis, NCSs can be divided into three categories: (1) physiological Ca²⁺/Zn²⁺ sensor proteins capable of binding exchangeable (signaling) zinc (recoverin and VILIP1), (2) pathological Ca²⁺/Zn²⁺ sensors responding only to aberrantly high free zinc concentrations by denaturation and aggregation (NCALD), and (3) Zn²⁺-resistant, Ca²⁺ sensor proteins (GCAP1, GCAP2). We suggest that NCS proteins may therefore govern the interconnection between Ca²⁺-dependent and Zn²⁺-dependent signaling pathways in healthy neurons and zinc cytotoxicity-related neurodegenerative diseases, such as Alzheimer’s disease and glaucoma.

Upregulation of N-Type Voltage-Gated Calcium Channels Induces Neuropathic Pain in Experimental Autoimmune Neuritis

Objective

Guillain-Barré syndrome (GBS) is a common autoimmune disease of the peripheral nervous system, and there is still no effective treatment for GBS. This investigation intends to figure out the effect and mechanism of N-type voltage-gated calcium (Cav2.2) channels on neuropathic pain in GBS.

Methods

An experimental autoimmune neuritis (EAN) model was established in Lewis rats induced by myelin P253-78 peptide and complete Freund's adjuvant. Luxol fast blue (LFB) staining was used for observing the degree of cell infiltration and demyelination in the sciatic nerve of rats, ELISA for detecting IL-6 and TNF-α expression in the serum, qRT-PCR, and Western blot for measuring the expression of iNOS, MCP-1, and Cav2.2 in the sciatic nerve, respectively.

Results

EAN led to significant decreases in the mechanical withdrawal threshold, thermal withdrawal threshold, and mechanical hyperalgesia threshold and an increase in the withdrawal threshold to cold stimulation. The serum IL-6 and TNF-α expression was significantly increased, and the mRNA and protein expression of iNOS, MCP-1, and Cav2.2 in the sciatic nerve were significantly increased in the EAN rats. However, silencing Cav2.2 expression could significantly reverse the above EAN-caused results.

Conclusion

Silencing Cav2.2 expression can significantly reduce the clinical score, pathological injury, and mechanical allodynia, reducing the release of inflammatory factors, thus improving neuropathic pain in EAN rats.

Ca2+ Dyshomeostasis Links Risk Factors to Neurodegeneration in Parkinson’s Disease

Parkinson’s disease (PD), a common neurodegenerative disease characterized by motor dysfunction, results from the death of dopaminergic neurons in the substantia nigra pars compacta (SNc). Although the precise causes of PD are still unknown, several risk factors for PD have been determined, including aging, genetic mutations, environmental factors, and gender. Currently, the molecular mechanisms underlying risk factor-related neurodegeneration in PD remain elusive. Endoplasmic reticulum stress, excessive reactive oxygen species production, and impaired autophagy have been implicated in neuronal death in the SNc in PD. Considering that these pathological processes are tightly associated with intracellular Ca²⁺, it is reasonable to hypothesize that dysregulation of Ca²⁺ handling may mediate risk factors-related PD pathogenesis. We review the recent findings on how risk factors cause Ca²⁺ dyshomeostasis and how aberrant Ca²⁺ handling triggers dopaminergic neurodegeneration in the SNc in PD, thus putting forward the possibility that manipulation of specific Ca²⁺ handling proteins and subcellular Ca²⁺ homeostasis may lead to new promising strategies for PD treatment.

Decoding the Bell-Shaped Calcium Spikes in Phosphorylation Cycles of Flagella

We investigate the messenger role of calcium ions implicated in the regulation of wave-like bending dynamics of flagella. The emphasis is on microtubules of flagellar axoneme serving as nonlinear transmission lines for bell-shaped spikes of calcium ions. The calcium sensitive proteins, such as calmodulin, exhibit activation dependence on the spike train frequency and amplitude. Here, we analyze a Ca²⁺ decoding module IDA-I1 whose activity is controlled by Ca²⁺ activated kinase. We find that trains of Ca²⁺ spikes are advantageous compared to a constant rise in Ca²⁺ concentration as being more efficient and much less prone to noisy fluctuations.

Dynamics of Neuromuscular Transmission Reproduced by Calcium-Dependent and Reversible Serial Transitions in the Vesicle Fusion Complex

Neuromuscular transmission, from spontaneous release to facilitation and depression, was accurately reproduced by a mechanistic kinetic model of sequential maturation transitions in the molecular fusion complex. The model incorporates three predictions. First, calcium-dependent forward transitions take vesicles from docked to preprimed to primed states, followed by fusion. Second, prepriming and priming are reversible. Third, fusion and recycling are unidirectional. The model was fed with experimental data from previous studies, whereas the backward (β) and recycling (ρ) rate constant values were fitted. Classical experiments were successfully reproduced with four transition states in the model when every forward (α) rate constant had the same value, and both backward rate constants were 50–100 times larger. Such disproportion originated an abruptly decreasing gradient of resting vesicles from docked to primed states. By contrast, a three-state version of the model failed to reproduce the dynamics of transmission by using the same set of parameters. Simulations predict the following: (1) Spontaneous release reflects primed to fusion spontaneous transitions. (2) Calcium elevations synchronize the series of forward transitions that lead to fusion. (3) Facilitation reflects a transient increase of priming following the calcium-dependent maturation transitions. (4) The calcium sensors that produce facilitation are those that evoke the transitions form docked to primed states. (5) Backward transitions and recycling restore the resting state. (6) Depression reflects backward transitions and slow recycling after intense release. Altogether, our results predict that fusion is produced by one calcium sensor, whereas the modulation of the number of vesicles that fuse depends on the calcium sensors that promote the early transition states. Such finely tuned kinetics offers a mechanism for collective non-linear transitional adaptations of a homogeneous vesicle pool to the ever-changing pattern of electrical activity in the neuromuscular junction.

Transcriptome of human neuroblastoma SH-SY5Y cells in response to 2B protein of enterovirus-A71

Infection with enterovirus-A71 (EV-A71) can cause hand-foot-mouth disease associated with fatal neurological complications. The host response to EV-A71 has not yet been fully elucidated, thus, hampering the development of a precise therapeutic approach. A nonstructural 2B protein of EV-A71 has been reported to involve with calcium dysregulation and apoptosis induction in human neuroblastoma SH-SY5Y cells. However, the molecular mechanism has not been delineated. To address this, comprehensive study of the gene expression from SH-SY5Y cells transfected with EV-A71 2B was carried out by RNA sequencing and transcriptomic analysis. It was found that the signature of the upregulated genes of SH-SY5Y cells expressing EV-A71 2B involved the Ca²⁺-related signaling pathways participating gene expression, inflammatory response, apoptosis, and long-term potentiation of the neuron. Protein-protein interaction network analysis revealed that the products encoded by CCL2, RELB, BIRC3, and TNFRSF9 were the most significant hub proteins in the network. It indicated that EV-A71 2B protein might play a role in immunopathogenesis of the central nervous system (CNS) which probably associated with the non-canonical NF-κB pathway. The data suggest that transcriptomic profiling can provide novel information source for studying the neuropathogenesis of EV-A71 infection leading to development of an effective therapeutic measure for CNS complications.

Hippocalcin-like 1 is a key regulator of LDHA activation that promotes the growth of non-small cell lung carcinoma

BACKGROUND

Hippocalcin-like 1 (HPCAL1), a neuronal calcium sensor protein family member, has been reported to regulate cancer growth. As yet, however, the biological functions of HPCAL1 and its molecular mechanisms have not been investigated in non-small cell lung carcinoma (NSCLC).

METHODS

HPCAL1 expression in NSCLC samples was detected using immunohistochemistry, Western blotting and RT-PCR. The anticancer effects of HPCAL1 knockdown were determined by MTT, soft agar, cell cycle, oxygen consumption and reactive oxygen species assays. The effect of HPCAL1 knockdown on in vivo tumor growth was assessed using NSCLC cancer patient-derived xenograft models. Potentially interacting protein partners of HPCAL1 were identified using IP-MS/MS, immunoprecipitation and Western blotting assays. Metabolic alterations resulting from HPCAL1 knockdown were investigated using non-targeted metabolomics and RNA sequencing analyses.

RESULTS

We found that HPCAL1 is highly expressed in NSCLC tissues and is positively correlated with low survival rates and AJCC clinical staging in lung cancer patients. Knockdown of HPCAL1 strongly increased oxygen consumption rates and the production of reactive oxygen species. HPCAL1 knockdown also inhibited NSCLC cell growth and patient-derived NSCLC tumor growth in vivo. Mechanistically, we found that HPCAL1 can directly bind to LDHA and enhance SRC-mediated phosphorylation of LDHA at tyrosine 10. The metabolomics and RNA sequencing analyses indicated that HPCAL1 knockdown reduces amino acid levels and induces fatty acid synthesis through regulating the expression of metabolism-related genes. Additionally, rescued cells expressing wild-type or mutant LDHA in HPCAL1 knockdown cells suggest that LDHA may serve as the main substrate of HPCAL1.

CONCLUSIONS

Our data indicate that the effect of HPCAL1 knockdown on reducing SRC-mediated LDHA activity attenuates NSCLC growth. Our findings reveal novel biological functions and a mechanism underlying the role of HPCAL1 in NSCLC growth in vitro and in vivo.

Alloy electrode engineering in memristors for emulating the biological synapse

The development of conductive bridging random access memory (CBRAM) as an artificial synaptic device is an important step in the realization of an efficient biomimetic neural morphology computing system. In fact, CBRAM devices with simple substance electrodes often form unstable and discrete conductive filaments, thereby resulting in poor device performance. In this work, the effects of different alloy electrode ratios on the performance of HfO_x devices with dielectric layers were systematically investigated via electrode composition engineering. The devices (a kind of memristor) with an Ag-Cu ratio of 63 : 37 exhibited a lower formation voltage and set voltage, better set voltage distribution uniformity, faster response speed, and lower power consumption than other devices. Moreover, the device is capable of emulating the biosynapse functions, including paired-pulse facilitation (PPF), post-tetanic potentiation (PTP), spike-rate-dependent plasticity (SRDP), and spike-timing-dependent plasticity (STDP). Interestingly, the associative learning process of Pavlov's dog experiment and aversion therapy were also realized without the use of complex external circuits. The use of electrode component engineering provides a new path for boosting the memristor properties via CBRAM devices, thereby laying the foundation for further development of neural morphology computing systems.

Gene family evolution underlies cell-type diversification in the hypothalamus of teleosts

Hundreds of cell types form the vertebrate brain but it is largely unknown how similar cellular repertoires are between or within species or how cell-type diversity evolves. To examine cell-type diversity across and within species, we performed single-cell RNA sequencing of ~130,000 hypothalamic cells from zebrafish (Danio rerio) and surface and cave morphs of Mexican tetra (Astyanax mexicanus). We found that over 75% of cell types were shared between zebrafish and Mexican tetra, which diverged from a common ancestor over 150 million years ago. Shared cell types displayed shifts in paralogue expression that were generated by subfunctionalization after genome duplication. Expression of terminal effector genes, such as neuropeptides, was more conserved than the expression of their associated transcriptional regulators. Species-specific cell types were enriched for the expression of species-specific genes and characterized by the neofunctionalization of expression patterns of members of recently expanded or contracted gene families. Comparisons between surface and cave morphs revealed differences in immune repertoires and transcriptional changes in neuropeptidergic cell types associated with genomic differences. The single-cell atlases presented here are a powerful resource to explore hypothalamic cell types and reveal how gene family evolution and shifts in paralogue expression contribute to cellular diversity.

Extracellular Secretagogin is internalized into the cells through endocytosis

Secretagogin (SCGN) is a calcium-sensor protein with a regulatory role in glucose metabolism and the secretion of several peptide hormones. Many, but not all, functions of SCGN can be explained by its intracellular manifestation. Despite early data on SCGN secretion, the secretory mechanism, biological fate, physiological implications, and trans-cellular signaling of extracellular SCGN remain unknown. We here report that extracellular SCGN is readily internalized into the C2C12 cells in an energy-dependent manner. Using endocytosis inhibitors, we demonstrate that SCGN internalizes via clathrin-mediated endocytosis, following which, SCGN localizes largely in the cytosol. Exogenous SCGN treatment induces a global proteomic reprogramming in C2C12 cells. Gene ontology search suggests that SCGN-induced proteomic reprogramming favors protein synthesis and cellular growth. We thus validated the cell proliferative action of SCGN using C2C12, HepG2, and NIH-3T3 cell lines. Based on the data, we propose that circulatory SCGN is internalized into the target cells and modulates the expression of cell growth-related proteins. The work suggests that extracellular SCGN is a functional protein, which communicates with specific cell types and directly modulates cell proliferation.

An Autonomous Molecular Bioluminescent Reporter (AMBER) for Voltage Imaging in Freely Moving Animals

Genetically encoded reporters have greatly increased our understanding of biology. While fluorescent reporters have been widely used, photostability and phototoxicity have hindered their use in long-term experiments. Bioluminescence overcomes some of these challenges but requires the addition of an exogenous luciferin limiting its use. Using a modular approach, Autonomous Molecular BioluminEscent Reporter (AMBER), an indicator of membrane potential is engineered. Unlike other bioluminescent systems, AMBER is a voltage-gated luciferase coupling the functionalities of the Ciona voltage-sensing domain (VSD) and bacterial luciferase, luxAB. When co-expressed with the luciferin-producing genes, AMBER reversibly switches the bioluminescent intensity as a function of membrane potential. Using biophysical and biochemical methods, it is shown that AMBER switches its enzymatic activity from an OFF to an ON state as a function of the membrane potential. Upon depolarization, AMBER switches from a low to a high enzymatic activity state, showing a several-fold increase in the bioluminescence output (ΔL/L). AMBER in the pharyngeal muscles and mechanosensory touch neurons of Caenorhabditis elegans is expressed. Using the compressed sensing approach, the electropharingeogram of the C. elegans pharynx is reconstructed, validating the sensor in vivo. Thus, AMBER represents the first fully genetically encoded bioluminescent reporter without requiring exogenous luciferin addition.

Disulfide Dimerization of Neuronal Calcium Sensor-1: Implications for Zinc and Redox Signaling

Neuronal calcium sensor-1 (NCS-1) is a four-EF-hand ubiquitous signaling protein modulating neuronal function and survival, which participates in neurodegeneration and carcinogenesis. NCS-1 recognizes specific sites on cellular membranes and regulates numerous targets, including G-protein coupled receptors and their kinases (GRKs). Here, with the use of cellular models and various biophysical and computational techniques, we demonstrate that NCS-1 is a redox-sensitive protein, which responds to oxidizing conditions by the formation of disulfide dimer (dNCS-1), involving its single, highly conservative cysteine C38. The dimer content is unaffected by the elevation of intracellular calcium levels but increases to 10–30% at high free zinc concentrations (characteristic of oxidative stress), which is accompanied by accumulation of the protein in punctual clusters in the perinuclear area. The formation of dNCS-1 represents a specific Zn²⁺-promoted process, requiring proper folding of the protein and occurring at redox potential values approaching apoptotic levels. The dimer binds Ca²⁺ only in one EF-hand per monomer, thereby representing a unique state, with decreased α-helicity and thermal stability, increased surface hydrophobicity, and markedly improved inhibitory activity against GRK1 due to 20-fold higher affinity towards the enzyme. Furthermore, dNCS-1 can coordinate zinc and, according to molecular modeling, has an asymmetrical structure and increased conformational flexibility of the subunits, which may underlie their enhanced target-binding properties. In HEK293 cells, dNCS-1 can be reduced by the thioredoxin system, otherwise accumulating as protein aggregates, which are degraded by the proteasome. Interestingly, NCS-1 silencing diminishes the susceptibility of Y79 cancer cells to oxidative stress-induced apoptosis, suggesting that NCS-1 may mediate redox-regulated pathways governing cell death/survival in response to oxidative conditions.

Transmembrane Protein Ttyh1 Maintains the Quiescence of Neural Stem Cells Through Ca2+/NFATc3 Signaling

The quiescence, activation, and subsequent neurogenesis of neural stem cells (NSCs) play essential roles in the physiological homeostasis and pathological repair of the central nervous system. Previous studies indicate that transmembrane protein Ttyh1 is required for the stemness of NSCs, whereas the exact functions in vivo and precise mechanisms are still waiting to be elucidated. By constructing Ttyh1-promoter driven reporter mice, we determined the specific expression of Ttyh1 in quiescent NSCs and niche astrocytes. Further evaluations on Ttyh1 knockout mice revealed that Ttyh1 ablation leads to activated neurogenesis and enhanced spatial learning and memory in adult mice (6-8 weeks). Correspondingly, Ttyh1 deficiency results in accelerated exhaustion of NSC pool and impaired neurogenesis in aged mice (12 months). By RNA-sequencing, bioinformatics and molecular biological analysis, we found that Ttyh1 is involved in the regulation of calcium signaling in NSCs, and transcription factor NFATc3 is a critical effector in quiescence versus cell cycle entry regulated by Ttyh1. Our research uncovered new endogenous mechanisms that regulate quiescence versus activation of NSCs, therefore provide novel targets for the intervention to activate quiescent NSCs to participate in injury repair during pathology and aging.

Specific Cognitive Changes due to Hippocalcin Alterations? A Novel Familial Homozygous Hippocalcin Variant Associated with Inherited Dystonia and Altered Cognition

BACKGROUND

Recent research suggested an hippocalcin (HPCA)-related form of DYT2-like autosomal recessive dystonia. Two reports highlight a broad spectrum of the clinical phenotype. Here, we describe a novel HPCA gene variant in a pediatric patient and two affected relatives.

METHODS

Whole exome sequencing was applied after a thorough clinical and neurological examination of the index patient and her family members. Results of neuropsychological testing were analyzed.

RESULTS

Whole exome sequencing revealed a novel homozygous missense variant in the HPCA gene [c.182C>T p.(Ala61Val)] in our pediatric patient and the two affected family members. Clinically, the cases presented with dystonia, dysarthria, and jerky movements. We observed a particular cognitive profile with executive dysfunctions in our patient, which corresponds to the cognitive deficits that have been observed in the patients previously described.

CONCLUSION

We present a novel genetic variant of the HPCA gene associated with autosomal recessive dystonia in a child with childhood-onset dystonia supporting its clinical features. Furthermore, we propose specific HPCA-related cognitive changes in homozygous carriers, underlining the importance of undertaking a systematic assessment of cognition in HPCA-related dystonia.

Calcium signal transmission by axonemal microtubules as an optimized information pathway in cilia and flagella

Calcium plays a key role in signal transduction in eukaryotic cells. Besides controlling local functions of cells calcium ions are responsible for the generation of global signals such as waves and spikes. Pulsatile increases of calcium concentrations are generally considered to have a much higher fidelity of information transfer than simple tonic changes, since they are much less prone to noisy fluctuations. In that respect, it was clearly revealed that Ca²⁺ has very crucial involvement in many signaling pathways in cilia and flagella. We earlier established a model in which axonemal microtubules exhibit the features of nonlinear polyelectrolitic electric transmissions lines for efficient transport of cations, primarily Ca²⁺. These microtubules guide accumulated "ionic clods" which serve as the pulsatile signals aimed to regulate pertaining motor proteins, dyneins and kinesis. We here consider such Ca²⁺ signals in axoneme in the context of Shannon's and Fisher's information theories. It appears that the fast drift of these "ionic clouds" represents the optimized calcium signaling for control of "flagellary beats" as well as intraflagellary transport of proteins essential for the construction, elongation and maintenance of eukaryotic cilia and flagella themselves.

Involvement of TRPV4 in changes in rapidly inactivating potassium channels in the early stage of pilocarpine-induced status epilepticus in mice

The rapidly inactivating potassium current (I_A ) is important in controlling neuronal action potentials. Altered I_A function and K⁺ channel expression have been found in epilepsy, and activation of the transient receptor potential vanilloid 4 (TRPV4) channel is involved in epilepsy pathogenesis. This study examined whether TRPV4 affects Kv4.2 and K⁺ channel interacting protein (KCHIP) expression and I_A changes following pilocarpine-induced status epilepticus (PISE) in mice. Herein, hippocampal protein levels of Kv4.2 and KCHIP2 increased 3 h-3 d and decreased 7-30 d; that of KCHIP1 increased 3-24 h and decreased 3-30 d post-PISE. The TRPV4 antagonist HC-067047 attenuated the increased protein levels of Kv4.2 and KCHIP2 but not that of KCHIP1 post-PISE. The TRPV4 agonist GSK1016790A increased hippocampal protein levels of Kv4.2 and KCHIP2 but had no effect on KCHIP1 expression. HC-067047 attenuated the increased I_A in hippocampal pyramidal neurons 24 h and 3 d post-PISE. GSK1016790A increased I_A in hippocampal pyramidal neurons, shifting the voltage-dependent inactivation curve toward depolarization. The GSK1016790A-induced increase of I_A was blocked by protein kinase A and calcium/calmodulin-dependent kinase II antagonists but was unaffected by protein kinase C antagonists. We conclude that TRPV4 activation may be responsible for the increases of Kv4.2 and KCHIP2 expression in hippocampi and I_A in hippocampal pyramidal neurons in PISE mice, which are likely compensatory measures for hyperexcitability at the early stage of epilepsy.

Oleuropein Activates Neonatal Neocortical Proteasomes, but Proteasome Gene Targeting by AAV9 Is Variable in a Clinically Relevant Piglet Model of Brain Hypoxia-Ischemia and Hypothermia

Cerebral hypoxia-ischemia (HI) compromises the proteasome in a clinically relevant neonatal piglet model. Protecting and activating proteasomes could be an adjunct therapy to hypothermia. We investigated whether chymotrypsin-like proteasome activity differs regionally and developmentally in the neonatal brain. We also tested whether neonatal brain proteasomes can be modulated by oleuropein, an experimental pleiotropic neuroprotective drug, or by targeting a proteasome subunit gene using recombinant adeno-associated virus-9 (AAV). During post-HI hypothermia, we treated piglets with oleuropein, used AAV-short hairpin RNA (shRNA) to knock down proteasome activator 28γ (PA28γ), or enforced PA28γ using AAV-PA28γ with green fluorescent protein (GFP). Neonatal neocortex and subcortical white matter had greater proteasome activity than did liver and kidney. Neonatal white matter had higher proteasome activity than did juvenile white matter. Lower arterial pH 1 h after HI correlated with greater subsequent cortical proteasome activity. With increasing brain homogenate protein input into the assay, the initial proteasome activity increased only among shams, whereas HI increased total kinetic proteasome activity. OLE increased the initial neocortical proteasome activity after hypothermia. AAV drove GFP expression, and white matter PA28γ levels correlated with proteasome activity and subunit levels. However, AAV proteasome modulation varied. Thus, neonatal neocortical proteasomes can be pharmacologically activated. HI slows the initial proteasome performance, but then augments ongoing catalytic activity. AAV-mediated genetic manipulation in the piglet brain holds promise, though proteasome gene targeting requires further development.

Proteomic and Transcriptomic Analyses Reveal Pathological Changes in the Entorhinal Cortex Region that Correlate Well with Dysregulation of Ion Transport in Patients with Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder. The earliest neuropathology of AD appears in entorhinal cortex (EC) regions. Therapeutic strategies and preventive measures to protect against entorhinal degeneration would be of substantial value in the early stages of AD. In this study, transcriptome based on the Illumina RNA-seq and proteome based on TMT-labelling were performed for RNA and protein profiling on AD EC samples and non-AD control EC samples. Immunohistochemistry was used to validate proteins expressions. After integrated analysis, 57 genes were detected both in transcriptome and proteome data, including 51 in similar altering trends (7 upregulated, 44 downregulated) and 6 in inverse trends when compared AD vs. control. The top 6 genes (GABRG2, CACNG3, CACNB4, GABRB2, GRIK2, and SLC17A6) within the 51 genes were selected and related to "ion transport". Correlation analysis demonstrated negative relationship of protein expression level with the neuropathologic changes. In conclusion, the integrate transcriptome and proteome analysis provided evidence for dysregulation of ion transport across brain regions in AD, which might be a critical signaling pathway that initiates pathology. This study might provide new insight into the earliest changes occurring in the EC of AD and novel targets for AD prevention and treatment.

PEGylated superparamagnetic iron oxide nanoparticles (SPIONs) ameliorate learning and memory deficit in a rat model of Alzheimer's disease: Potential participation of STIMs

The amyloid-beta (Aβ) fibrillation process seems to execute a principal role in the neuropathology of Alzheimer's disease (AD). Accordingly, novel therapeutic plans have concentrated on the inhibition or degradation of Aβ oligomers and fibrils. Biocompatible nanoparticles (NPs), e.g., gold and iron oxide NPs, take a unique capacity in redirecting Aβ fibrillation kinetics; nevertheless, their impacts on AD-related memory impairment have not been adequately evaluated in vivo. Here, we examined the effect of commercial PEGylated superparamagnetic iron oxide nanoparticles (SPIONs) on the learning and memory of an AD-animal model. The outcomes demonstrated the dose-dependent effect of SPIONs on Aβ fibrillation and learning and memory processes. In vitro and in vivo findings revealed that Low doses of SPIONs inhibited Aβ aggregation and ameliorated learning and memory deficit in the AD model, respectively. Enhanced level of hippocampal proteins, including brain-derived neurotrophic factor, BDNF, phosphorylated-cAMP response element-binding protein, p-CREB, and stromal interaction molecules, e.g., STIM1 and STIM2, were also observed. However, at high doses, SPIONs did not improve the detrimental impacts of Aβ fibrillation on spatial memory and hippocampal proteins expression. Overall, we revealed the potential capacity of SPIONs on retrieval of behavioral and molecular manifestations of AD in vivo, which needs further investigations to determine the mechanistic effect of SPIONs in the AD conundrum.

Transcriptomic analysis of human brains with Alzheimer's disease reveals the altered expression of synaptic genes linked to cognitive deficits

Alzheimer's disease is a progressive neurodegenerative disorder associated with memory loss and impaired executive function. The molecular underpinnings causing cognitive deficits in Alzheimer's disease are loosely understood. Here, we performed cross-study large-scale transcriptomic analyses of postmortem prefrontal cortex derived from Alzheimer's disease patients to reveal the role of aberrant gene expression in this disease. We identified that one of the most prominent changes in prefrontal cortex of Alzheimer's disease humans was the downregulation of genes in excitatory and inhibitory neurons that are associated with synaptic functions, particularly the SNARE-binding complex, which is essential for vesicle docking and neurotransmitter release. Comparing genomic data of Alzheimer's disease with proteomic data of cognitive trajectory, we found that many of the lost synaptic genes in Alzheimer's disease encode hub proteins whose increased abundance is required for cognitive stability. This study has revealed potential molecular targets for therapeutic intervention of cognitive decline associated with Alzheimer's disease.

Nonvolatile resistive switching and synaptic characteristics of lead-free all-inorganic perovskite-based flexible memristive devices for neuromorphic systems

Recently, several types of lead halide perovskites have been actively researched for resistive switching (RS) memory or artificial synaptic devices due to their current-voltage hysteresis along with the feasibility of fabrication, low-temperature processability and superior charge mobility. However, the toxicity and environmental pollution potential of lead halide perovskites severely restrict their large-scale commercial prospects. In the present work, the environmentally friendly and uniform CsSnCl₃ perovskite films are introduced to act as an active layer in the flexible memristors. Ag/CsSnCl₃/ITO devices demonstrate bipolar RS with excellent electrical properties such as forming free characteristics, good uniformity, low operating voltages, a high ON/OFF ratio (10²) and a long retention time (>10⁴ s). The RS mechanism has been well explained in the outline of electric field-induced formation and rupture of Ag filaments in the CsSnCl₃ layer. The metallic nature of the conducting filament has been further confirmed by temperature-dependent variation of low and high resistance states. Additionally, various pulse measurements have been carried out to mimic some of the basic synaptic functions including postsynaptic current, paired-pulse facilitation, long-term potentiation and long-term depression under normal as well as bending conditions. Our work provides the opportunity for exploring artificial synapses based on lead-free halide perovskites for the development of next-generation flexible electronics.