CaMKII: a central molecular organizer of synaptic plasticity, learning and memory

Pea protein hydrolysate stimulates GLP-1 secretion in NCI-H716 cells via simultaneously activating the sensing receptors CaSR and PepT1

Glucagon-like peptide-1 (GLP-1) plays a crucial role in regulating glucose homeostasis by stimulating insulin secretion and suppressing glucagon release. Our previous study observed that pea protein hydrolysate (PPH) exhibited the function of triggering GLP-1 secretion. However, the underlying mechanisms have not been revealed. Herein, the mechanisms of PPH-stimulated GLP-1 secretion were investigated in NCI-H716 cells. The PPH-induced GLP-1 secretion was reduced (p < 0.05) after adding the sensing receptor antagonists NPS-2143 and 4-AMBA, indicating that activation of both calcium-sensing receptor (CaSR) and peptide-transporter 1 (PepT1) was involved in PPH-triggered GLP-1 release. Moreover, the intracellular Ca2+ level increased by 2.01 times during the PPH-induced GLP-1 secretion. Similarly, the cAMP content also increased by 1.43 times after stimulation by PPH. The RT-qPCR results showed that PPH increased the gene expression of prohormone convertase 1/3 (PCSK-1) by 2.79-fold, which effectively promoted the conversion of proglucagon (GCG) to GLP-1. The specific pathway of PPH-induced GLP-1 secretion may involve both CaSR and PepT1 activation-induced Ca2+ influx and cAMP generation, which effectively enhanced the enzyme activity of prohormone convertase 1/3 (PCSK-1) and ultimately promoted GLP-1 secretion.

Pathophysiological impacts of 5-MeO-MiPT on zebrafish (Danio rerio) via the Gαq/11-PLCβ signaling pathway

Novel Psychoactive Substances (NPS) derived from tryptamines has been detected in aquatic environments, leading to environmental toxicology concerns. However, the specific toxicological mechanism, underlying these NPS, remains unclear. In our previous work, we used 5-Methoxy-N-isopropyl-N-methyltryptamine (5-MeO-MiPT) as the representative drug for NPS, and found that, 5-MeO-MiPT led to obvious behavioral inhibition and oxidative stress responses in zebrafishes model. In this study, Zebrafish were injected with varying concentrations of 5-MeO-MiPT for 30 days. RNA-seq, qPCR, metabolomics, and histopathological analyses were conducted to assess gene expression and tissue integrity. This study confirms that 5-MeO-MiPT substantially influences the transcription and expression of 13 selected genes, including ucp1, pet100, grik3, and grik4, mediated by the Gαq/11-PLCβ signaling pathway. We elucidate the molecular mechanism that 5-MeO-MiPT can inhibit DAG-Ca2+/Pkc/Erk, Pkc/Pla2/PLCs and Ca2+/Camk Ⅱ/NMDA, while enhance Ca2+/Creb. Those secondary signaling pathways may be the mechanisms mediating 5-MeO-MiPT inhibiting normal behavior in zebrafish. These findings offer novel insights into the toxicological effects and addiction mechanisms of 5-MeO-MiPT. Moreover, it presents promising avenues for investigating other tryptamine-based NPS and offers a new direction for diagnosing and treating liver-brain pathway-related diseases.

Phosphorylation of tau at a single residue inhibits binding to the E3 ubiquitin ligase, CHIP

Microtubule-associated protein tau (MAPT/tau) accumulates in a family of neurodegenerative diseases, including Alzheimer's disease (AD). In disease, tau is aberrantly modified by post-translational modifications (PTMs), including hyper-phosphorylation. However, it is often unclear which of these PTMs contribute to tau's accumulation or what mechanisms might be involved. To explore these questions, we focus on a cleaved proteoform of tau (tauC3), which selectively accumulates in AD and was recently shown to be degraded by its direct binding to the E3 ubiquitin ligase, CHIP. Here, we find that phosphorylation of tauC3 at a single residue, pS416, is sufficient to weaken its interaction with CHIP. A co-crystal structure of CHIP bound to the C-terminus of tauC3 reveals the mechanism of this clash, allowing design of a mutation (CHIPD134A) that partially restores binding and turnover of pS416 tauC3. We confirm that, in our models, pS416 is produced by the known AD-associated kinase, MARK2/Par-1b, providing a potential link to disease. In further support of this idea, an antibody against pS416 co-localizes with tauC3 in degenerative neurons within the hippocampus of AD patients. Together, these studies suggest a molecular mechanism for how phosphorylation at a discrete site contributes to accumulation of a tau proteoform.

The effects of different types of social interactions on the electrophysiology of neurons in the nucleus accumbens in rodents

BORLAND, J.M., The effects of different types of social interactions on the electrophysiology of neurons in the nucleus accumbens in rodents, NEUROSCI BIOBEH REV 21(1) XXX-XXX, 2024.-Sociality shapes an organisms' life. The nucleus accumbens is a critical brain region for mental health. In the following review, the effects of different types of social interactions on the physiology of neurons in the nucleus accumbens is synthesized. More specifically, the effects of sex behavior, aggression, social defeat, pair-bonding, play behavior, affiliative interactions, parental behaviors, the isolation from social interactions and maternal separation on measures of excitatory synaptic transmission, intracellular signaling and factors of transcription and translation in neurons in the nucleus accumbens in rodent models are reviewed. Similarities and differences in effects depending on the type of social interaction is then discussed. This review improves the understanding of the molecular and synaptic mechanisms of sociality.

Molecular regulation of calcium-sensing receptor (CaSR)-mediated signaling

Calcium-sensing receptor (CaSR), a family C G-protein-coupled receptor, plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca2+, Mg2+, amino acids (e.g., L-Trp and L-Phe), small peptides, anions (e.g., HCO3 - and PO4 3-), and pH. CaSR-mediated intracellular Ca2+ signaling regulates a diverse set of cellular processes including gene transcription, cell proliferation, differentiation, apoptosis, muscle contraction, and neuronal transmission. Dysfunction of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia, and neonatal severe hyperparathyroidism. CaSR also influences calciotropic disorders, such as osteoporosis, and noncalciotropic disorders, such as cancer, Alzheimer's disease, and pulmonary arterial hypertension. This study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands, as well as exogenous positive allosteric modulators and negative allosteric modulators. The establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum, trafficking, cell surface expression, endocytosis, degradation, and signaling pathways. The roles of these proteins in Ca2+-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.

Neural Correlates of Early-Life Urbanization and Their Spatial Relationships with Gene Expression, Neurotransmitter, and Behavioral Domain Atlases

Previous neuroimaging research has established associations between urban exposure during early life and alterations in brain function and structure. However, the molecular mechanisms and behavioral relevance of these associations remain largely unknown. Here, we aimed to address this question using a combined analysis of multimodal data. Initially, we calculated amplitude of low-frequency fluctuations (ALFF) and gray matter volume (GMV) using resting-state functional and structural MRI to investigate their associations with early-life urbanization in a large sample of 511 healthy young adults. Then, we examined the spatial relationships of the identified neural correlates of early-life urbanization with gene expression, neurotransmitter, and behavioral domain atlases. Results showed that higher early-life urbanization scores were correlated with increased ALFF of the right fusiform gyrus and decreased GMV of the left dorsal medial prefrontal cortex and left precuneus. Remarkably, the identified neural correlates of early-life urbanization were spatially correlated with expression of gene categories primarily involving immune system process, signal transduction, and cellular metabolic process. Concurrently, there were significant associations between the neural correlates and specific neurotransmitter systems including dopamine, acetylcholine, and serotonin. Finally, we found that the ALFF correlates were associated with behavioral terms including "perception," "sensory," "cognitive control," and "reasoning." Apart from expanding existing knowledge of early-life urban environmental risk for mental disorders and health in general, our findings may contribute to an emerging framework for integrating social science, neuroscience, genetics, and public policy to respond to the major health challenge of world urbanization.

Screening for optimal parameters for modified pharyngeal electrical stimulation for the treatment of dysphagia after stroke in rats

Pharyngeal electrical stimulation (PES), a novel noninvasive peripheral nerve stimulation technique, can effectively improve neurogenic dysphagia and increase the safety and effectiveness of swallowing in the clinic. However, the lack of animal models for dysphagia has limited the mechanistic research on PES, which affects its wide application. Therefore, determining optimal parameters for PES in rats is needed to enable mechanistic studies. Modified PES (mPES), which has different waves and pulse widths from PES, was used; in previous studies mPES was found to have a neurological mechanism like that of PES. A poststroke dysphagia (PSD) model was established, and rats with dysphagia were grouped into three different intensities (0.1 mA, 0.5 mA, and 1 mA) for the selection of optimal intensity and three different frequencies (1 Hz, 2 Hz, and 5 Hz) for the selection of optimal frequency based on a stimulation duration of 10 min in the clinic. A Videofluroscopic Swallow Screen (VFSS) was used to assess swallowing function in rats before and after mPES treatment. The results showed that the 1 mA group had better swallowing function (p < 0.05) than the model group. Compared with the model group, the 1 Hz and 5 Hz groups had the same improvement in swallowing function (p < 0.05). However, the increase in excitatory signals in the sensorimotor cortex was more pronounced in the 5 Hz group than in the other frequency stimulation groups (p < 0.05). Combining the clinical findings with the above results, we concluded that the optimal stimulation parameter for mPES in rats is "frequency: 5 Hz, current intensity: 1 mA for 10 min/day", which provides a basis for future basic experimental studies of mPES in animals.

Synaptic rearrangement of NMDA receptors controls memory engram formation and malleability in the cortex

Initially hippocampal dependent, memory representations rely on a broadly distributed cortical network as they mature over time. How these cortical engrams acquire stability during systems-level memory consolidation without compromising their dynamic nature remains unclear. We identified a highly responsive "consolidation switch" in the synaptic composition of N-methyl-d-aspartate receptors (NMDARs), which dictates the progressive embedding and persistence of enduring memories in the rat cortex. Cortical GluN2B subunit-containing NMDARs were preferentially recruited upon encoding of associative olfactory memory to support neuronal allocation of memory engrams. As consolidation proceeds, a learning-induced redistribution of GluN2B subunit-containing NMDARs outward synapses increased synaptic GluN2A subunit contribution and enabled stabilization of remote memories. In contrast, synaptic reincorporation of GluN2B subunits occurred during subsequent forgetting. By manipulating the surface distribution of GluN2A and GluN2B subunit-containing NMDARs at cortical synapses, we uncovered that the rearrangement of GluN2B-containing NMDARs constitutes an essential tuning mechanism that determines the fate of cortical memory engrams and controls their malleability.

LT-102, an AMPA receptor potentiator, alleviates depression-like behavior and synaptic plasticity impairments in prefrontal cortex induced by sleep deprivation

BACKGROUND

Sleep loss is closely related to the onset and development of depression, and the mechanisms involved may include impaired synaptic plasticity. Considering the important role of glutamate α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) in synaptic plasticity as well as depression, we introduce LT-102, a novel AMPARs potentiator, to evaluate the potential of LT-102 in treating sleep deprivation-induced depression-like behaviors.

METHODS

We conducted a comprehensive behavioral assessment to evaluate the effects of LT-102 on depression-like symptoms in male C57BL/6J mice. This assessment included the open field test to measure general locomotor activity and anxiety-like behavior, the forced swimming test and tail suspension test to assess despair behaviors indicative of depressive states, and the sucrose preference test to quantify anhedonia, a core symptom of depression. Furthermore, to explore the impact of LT-102 on synaptic plasticity, we utilized a combination of Western blot analysis to detect protein expression levels, Golgi-Cox staining to visualize neuronal morphology, and immunofluorescence to examine the localization of synaptic proteins. Additionally, we utilized primary cortical neurons to delineate the signaling pathway modulated by LT-102.

RESULTS

Treatment with LT-102 significantly reduced depression-like behaviors associated with sleep deprivation. Quantitative Western blot (WB) analysis revealed a significant increase in GluA1 phosphorylation in the prefrontal cortex (PFC), triggering the Ca2+/calmodulin-dependent protein kinase II/cAMP response element-binding protein/brain-derived neurotrophic factor (CaMKII/CREB/BDNF) and forkhead box protein P2/postsynaptic density protein 95 (FoxP2/PSD95) signaling pathways. Immunofluorescence imaging confirmed that LT-102 treatment increased spine density and co-labeling of PSD95 and vesicular glutamate transporter 1 (VGLUT1) in the PFC, reversing the reductions typically observed following sleep deprivation. Golgi staining further validated these results, showing a substantial increase in neuronal dendritic spine density in sleep-deprived mice treated with LT-102. Mechanistically, application of LT-102 to primary cortical neurons, resulted in elevated levels of phosphorylated AKT (p-AKT) and phosphorylated glycogen synthase kinase-3 beta (p-GSK3β), key downstream molecules in the BDNF signaling pathway, which in turn upregulated FoxP2 and PSD95 expression.

LIMITATIONS

In our study, we chose to exclusively use male mice to eliminate potential influences of the estrous cycle on behavior and physiology. As there is no widely accepted positive drug control for sleep deprivation studies, we did not include one in our research.

CONCLUSION

Our results suggest that LT-102 is a promising therapeutic agent for counteracting depression-like behaviors and synaptic plasticity deficits induced by sleep deprivation, primarily through the activation of CaMKII/CREB/BDNF and AKT/GSK3β/FoxP2/PSD95 signaling pathways.

Post-stroke whole body vibration therapy alters the cerebral transcriptome to promote ischemic tolerance in middle-aged female rats

Low-frequency whole body vibration (WBV; 40 Hz) therapy after stroke reduces ischemic brain damage, motor, and cognitive deficits in middle-aged rats of both sexes. However, the underlying mechanisms responsible for WBV induced ischemic protections remain elusive. In the current study, we hypothesize that post-stroke WBV initiates transcriptional reprogramming in the cortex of middle-aged female rats which is responsible for the observed reduced stroke consequences. Middle-aged female Sprague-Dawley rats that remained in constant diestrus (reproductively senescent) were randomized to either sham or transient middle cerebral artery occlusion (tMCAO; 90 min) surgery. A day after induction of tMCAO, animals received either WBV or no-WBV treatment for 15 min twice a day for five days for a week. Post-treatment, cortical tissue was analyzed for gene expression using RNA sequencing (RNAseq) and gene enrichment analysis via Enrichr. The RNAseq data analysis revealed significant changes in gene expression due to WBV therapy and the differentially expressed genes are involved in variety of biological processes like neurogenesis, angiogenesis, excitotoxicity, and cell death. Specifically, observed significant up-regulation of 116 and down-regulation of 258 genes after WBV in tMCAO exposed rats as compared to the no-WBV group. The observed transcriptional reprogramming will identify the possible mechanism(s) responsible for post-stroke WBV conferred ischemic protection and future studies will be needed to confirm the role of the genes identified in the current study.

Arc and BDNF mediated effects of hippocampal astrocytic glutamate uptake blockade on spatial memory stages

Glutamate is involved in fundamental functions, including neuronal plasticity and memory. Astrocytes are integral elements involved in synaptic function, and the GLT-1 transporter possesses a critical role in glutamate uptake. Here, we study the role of GLT-1, specifically located in astrocytes, in the consolidation, expression, reconsolidation and persistence of spatial object recognition memory in rats. Administration of dihydrokainic acid (DHK), a selective GLT-1 inhibitor, into the dorsal hippocampus around a weak training which only induces short-term memory, promotes long-term memory formation. This promotion is prevented by hippocampal administration of protein-synthesis translation inhibitor, blockade of Activity-regulated cytoskeleton-associated protein (Arc) translation or Brain-Derived Neurotrophic Factor (BDNF) action, which are plasticity related proteins necessary for memory consolidation. However, DHK around a strong training, which induces long-term memory, does not affect memory consolidation. Administration of DHK before the test session impairs the expression of long-term memory, and this effect is dependent of Arc translation. Furthermore, DHK impairs reconsolidation if applied before a reactivation session, and this effect is independent of Arc translation. These findings reveal specific consequences on spatial memory stages developed under hippocampal GLT-1 blockade, shedding light on the intricate molecular mechanisms, governed in part for the action of glia.

The phosphorylation of Smad3 by CaMKIIγ leads to the hepatocyte pyroptosis under perfluorooctane sulfonate exposure

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant and accumulated in the liver of mammals. PFOS exposure is closely associated with the development of pyroptosis. Nevertheless, the underlying mechanism is unclear. We found here that PFOS induced pyroptosis in the mice liver and L-02 cells as demonstrated by activation of the NOD-like receptor protein 3 inflammasome, gasdermin D cleavage and increased release of interleukin-1β and interleukin-18. The level of cytoplasmic calcium was accelerated in hepatocytes upon exposure to PFOS. The phosphorylated/activated form of calcium/calmodulin-dependent protein kinase II (CaMKII) was augmented by PFOS in vivo and in vitro. PFOS-induced pyroptosis was relieved by CaMKII inhibitor. Among various CaMKII subtypes, we identified that CaMKIIγ was activated specifically by PFOS. CaMKIIγ interacted with Smad family member 3 (Smad3) under PFOS exposure. PFOS increased the phosphorylation of Smad3, and CaMKII inhibitor or CaMKIIγ siRNA alleviated PFOS-caused phosphorylation of Smad3. Inhibiting Smad3 activity was found to alleviate PFOS-induced hepatocyte pyroptosis. This study puts forward that CaMKIIγ-Smad3 is the linkage between calcium homeostasis disturbance and pyroptosis, providing a mechanistic explanation for PFOS-induced pyroptosis.

CAMK2G Promotes Neuronal Differentiation and Inhibits Migration in Neuroblastoma

PURPOSE

Neuroblastoma (NB) originates from differentiation arrest of sympathoadrenal progenitors in the neural crest. It is necessary to reveal the differentiation mechanism of NB. Previously, we reported that Purkinje cell protein 4 (PCP4) is a well-differentiated marker of NB tissues. Herein, we explored the underlying mechanism of PCP4 induced differentiation in order to find better treatment options for patients.

METHODS

We screened the interacting proteins of PCP4 by co-immunoprecipitation (Co-IP) and liquid chromatography-mass spectrometry (LC-MS/MS). Then we investigated the relevance between expression of calmodulin-dependent protein kinase II gamma (CAMK2G) and clinical features using R2 platform. We also explored the function of CAMK2G in NB cells by knockdown and RNA sequencing.

RESULTS

Here, we verified the binding of PCP4 and calmodulin (CaM) by Co-IP and identified a target kinase of CaM, CAMK2G, by LC-MS/MS. PCP4 overexpression activates the autophosphorylation of CAMK2G. Patients with high CAMK2G expression had better survival while low CAMK2G was associated with unfavorable clinical features including MYCN-amplification, unfavorable histology, progression and high INSS stage. CAMK2G knockdown inhibited neurite outgrowth and down-regulated neuronal differentiation markers (NF-H, MAP2), yet promoted migration, invasion and proliferation. Gene Ontology (GO) analysis showed that knockdown of CAMK2G downregulated the expression of neuronal differentiation-related genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that knockdown of CAMK2G upregulated the expression of migration-related genes.

CONCLUSION

These findings indicate that CAMK2G activated by PCP4/CaM complex promotes differentiation and inhibits migration in NB cells.

LEVEL OF EVIDENCE

Not applicable.

Participation of Ca2+-Calmodulin-Dependent Protein Kinase II in the Antidepressant-Like Effects of Melatonin

Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine secreted by the pineal gland during the dark phase of the photoperiod. Its main function is the synchronization of different body rhythms with the dark-light cycle. Research on melatonin has significantly advanced since its discovery and we now know that it has considerable significance in various physiological processes, including immunity, aging, and reproduction. Moreover, in recent years evidence of the pharmacological possibilities of melatonin has increased. Indoleamine, on the other hand, has antidepressant-like effects in rodents, which may be mediated by the activation of calcium-calmodulin-dependent kinase II (CaMKII) and are also related to the regulation of neuroplasticity processes, including neurogenesis, synaptic maintenance, and long-term potentiation. Remarkably, patients with major depression show decreased levels of circulating melatonin in plasma. This review presents evidence of the antidepressant-like effects of melatonin in preclinical models and the participation of CaMKII in these actions. CaMKII's role in cognition and memory processes, which are altered in depressive states, are part of the review, and the effects of melatonin in these processes are also reviewed. Furthermore, participation of CaMKII on structural and synaptic plasticity and the effects of melatonin are also described. Finally, the advantages of using melatonin in combination with other antidepressants such as ketamine for neuroplasticity are described. Evidence supports that CaMKII is activated by melatonin and downstream melatonin receptors and may be the common effector in the synergistic effects of melatonin with other antidepressants. SIGNIFICANCE STATEMENT: This review compiled evidence supporting that melatonin causes antidepressant-like effects in mice through calmodulin kinase II stimulation of downstream melatonin receptors as well as the participation of this enzyme in neuroplasticity, memory, and cognition. Finally, we describe evidence about the effectiveness of antidepressant-like effects of melatonin in combination with ketamine.

Compound heterozygous mutations of NTNG2 cause intellectual disability via inhibition of the CaMKII signaling

Netrin-G2 is a membrane-anchored protein and is known to play critical roles in neuronal circuit development and synaptic organization. In this study, we identify compound heterozygous mutations of c.547delC, p.(Arg183Alafs*186) and c.605G>A, p.(Trp202*) in NTNG2 causing a syndrome exhibiting developmental delay, intellectual disability, hypotonia, and facial dysmorphism. To elucidate the underlying cellular and molecular mechanisms, CRISPR-Cas9 technology is employed to generate a knock-in mouse model expressing the R183Afs and W202X mutations. We report that the Ntng2R183Afs/W202X mice exhibit hypotonia and impaired learning and memory. We find that levels of CaMKII and p-GluA1Ser831 are decreased and excitatory postsynaptic transmission and long-term potentiation are impaired. To increase the activity of CaMKII, the mutant mice have received intraperitoneal injections of DCP-LA, a CaMKII agonist, and show improved cognitive function. Together, our findings reveal molecular mechanisms of how NTNG2 deficiency leads to impairments of cognitive ability and synaptic plasticity.

Ruxolitinib as a CaMKII inhibitor for treatment of cardiac arrhythmias: Applications and prospects

Recent studies have highlighted the critical role of calcium/calmodulin-dependent protein kinase II (CaMKII) overactivation in the pathogenesis of various cardiac arrhythmias. Ruxolitinib, a Janus kinase inhibitor widely used for the treatment of myelofibrosis and acute graft-vs-host disease, has expanded its research horizons to include its potential as a CaMKII inhibitor in the treatment of cardiac arrhythmias. This article reviews the basic pharmacologic properties of ruxolitinib and delves into the role of CaMKII in cardiac arrhythmias, including its structural fundamentals, activation mechanisms, and association with arrhythmic conditions. Furthermore, the current state of CaMKII inhibitor research is discussed, with a special focus on the advances and clinical potential of ruxolitinib in this field. Studies indicate that ruxolitinib effectively inhibits CaMKII activity and has therapeutic potential against cardiac arrhythmias in animal models and at the cellular level. In addition, we address the critical issues that need to be resolved before the clinical application of ruxolitinib in arrhythmia treatment, including dosage concerns, long-term inhibitory effects, potential impacts on the nervous system, and efficacy across different types of arrhythmias. Future research directions involve further exploration of the clinical application potential of ruxolitinib, particularly in diseases such as heart failure, hypertrophic cardiomyopathy, dilated cardiomyopathy, and ischemic arrhythmias. In summary, the efficacy, low toxicity, and safety profile of ruxolitinib as a CaMKII inhibitor in the treatment of cardiac arrhythmias suggest a promising future for its development as a therapeutic drug in this domain.

Myosin Va-dependent Transport of NMDA Receptors in Hippocampal Neurons

N-methyl-D-aspartate receptor (NMDAR) trafficking is a key process in the regulation of synaptic efficacy and brain function. However, the molecular mechanism underlying the surface transport of NMDARs is largely unknown. Here we identified myosin Va (MyoVa) as the specific motor protein that traffics NMDARs in hippocampal neurons. We found that MyoVa associates with NMDARs through its cargo binding domain. This association was increased during NMDAR surface transport. Knockdown of MyoVa suppressed NMDAR transport. We further demonstrated that Ca2+/calmodulin-dependent protein kinase II (CaMKII) regulates NMDAR transport through its direct interaction with MyoVa. Furthermore, MyoVa employed Rab11 family-interacting protein 3 (Rab11/FIP3) as the adaptor proteins to couple themselves with NMDARs during their transport. Accordingly, the knockdown of FIP3 impairs hippocampal memory. Together, we conclude that in hippocampal neurons, MyoVa conducts active transport of NMDARs in a CaMKII-dependent manner.

Action and therapeutic targets of myosin light chain kinase, an important cardiovascular signaling mechanism

The global incidence of cardiac diseases is increasing, imposing a substantial socioeconomic burden on healthcare systems. The pathogenesis of cardiovascular disease is complex and not fully understood, and the physiological function of the heart is inextricably linked to well-regulated cardiac muscle movement. Myosin light chain kinase (MLCK) is essential for myocardial contraction and diastole, cardiac electrophysiological homeostasis, vasoconstriction of vascular nerves and blood pressure regulation. In this sense, MLCK appears to be an attractive therapeutic target for cardiac diseases. MLCK participates in myocardial cell movement and migration through diverse pathways, including regulation of calcium homeostasis, activation of myosin light chain phosphorylation, and stimulation of vascular smooth muscle cell contraction or relaxation. Recently, phosphorylation of myosin light chains has been shown to be closely associated with the activation of myocardial exercise signaling, and MLCK mediates systolic and diastolic functions of the heart through the interaction of myosin thick filaments and actin thin filaments. It works by upholding the integrity of the cytoskeleton, modifying the conformation of the myosin head, and modulating innervation. MLCK governs vasoconstriction and diastolic function and is associated with the activation of adrenergic and sympathetic nervous systems, extracellular transport, endothelial permeability, and the regulation of nitric oxide and angiotensin II. Additionally, MLCK plays a crucial role in the process of cardiac aging. Multiple natural products/phytochemicals and chemical compounds, such as quercetin, cyclosporin, and ML-7 hydrochloride, have been shown to regulate cardiomyocyte MLCK. The MLCK-modifying capacity of these compounds should be considered in designing novel therapeutic agents. This review summarizes the mechanism of action of MLCK in the cardiovascular system and the therapeutic potential of reported chemical compounds in cardiac diseases by modifying MLCK processes.

µPhos: a scalable and sensitive platform for high-dimensional phosphoproteomics

Mass spectrometry has revolutionized cell signaling research by vastly simplifying the analysis of many thousands of phosphorylation sites in the human proteome. Defining the cellular response to perturbations is crucial for further illuminating the functionality of the phosphoproteome. Here we describe µPhos ('microPhos'), an accessible phosphoproteomics platform that permits phosphopeptide enrichment from 96-well cell culture and small tissue amounts in <8 h total processing time. By greatly minimizing transfer steps and liquid volumes, we demonstrate increased sensitivity, >90% selectivity, and excellent quantitative reproducibility. Employing highly sensitive trapped ion mobility mass spectrometry, we quantify ~17,000 Class I phosphosites in a human cancer cell line using 20 µg starting material, and confidently localize ~6200 phosphosites from 1 µg. This depth covers key signaling pathways, rendering sample-limited applications and perturbation experiments with hundreds of samples viable. We employ µPhos to study drug- and time-dependent response signatures in a leukemia cell line, and by quantifying 30,000 Class I phosphosites in the mouse brain we reveal distinct spatial kinase activities in subregions of the hippocampal formation.

Zexieyin formula alleviates Alzheimer's disease via post-synaptic CaMKII modulating AMPA receptor: Involved in promoting neurogenesis to strengthen synaptic plasticity in mice hippocampus

BACKGROUND

Alzheimer's disease (AD) is a serious neurodegenerative disease and brings a serious burden to society and families. Due to lack of effective drugs for the treatment of AD, it's urgent to develop new and effective drug for the treatment of AD.

PURPOSE

The study aimed to investigate the potential of Zexieyin formula (ZXYF), a Chinese medicine formula, for the treatment of AD and its potential mechanism of action.

METHODS

We used chronic scopolamine (SCOP) induction mice model and APP/PS1 mice to reveal and confirm ZXYF for the treatment of AD with donepezil (DON) as a positive reference. The learning and memory function were detected by morris water maze test (MWM) and y-maze test. Moreover, western blot and immunofluorescence were used to detect the molecular mechanism of ZXYF for the alleviation of AD in hippocampus. Lastly, pharmacological technology was applied to evaluate AMPA receptor involved in the role of ZXYF in the treatment of AD.

RESULTS

The results showed that ZXYF could improve memory and learning deficits both in two AD models including scopolamine (SCOP)-induced mice model and APP/PS1mice. Moreover, ZXYF or not DON increased expressions of BrdU/DCX and Ki67 positive cells in dentate gyrus (DG), up-regulated the levels of AMPA subunit type (GluA1) and PKA in hippocampus in SCOP-induced mice model, although ZXYF and DON activated CaMKII, CaMKII-phosphorylation, CREB, CREB-phosphorylation and PSD95 in hippocampus in SCOP-induced mice model. ZXYF also activated CaMKII, CaMKII-phosphorylation and GluA1 in HT22 cells. Furthermore, transient inhibiting AMPA receptor was capable of blocking the effects of ZXYF to treat AD in MWM and suppressing the number of BrdU/DCX positive cells increased by ZXYF in DG in SCOP-induced mice model, but had no effect on the alteration of Ki67 positive cells.

CONCLUSION

ZXYF had the therapeutic effects on AD-treatment, which activated CaMKII to promote AMPA receptor (GluA1) and subsequently up-regulated PKA/CREB signaling to facilitate neurogenesis to achieve enhanced postsynaptic protein.

α-Tocotrienol Protects Neurons by Preventing Tau Hyperphosphorylation via Inhibiting Microtubule Affinity-Regulating Kinase Activation

In the pathological process of Alzheimer's disease, neuronal cell death is closely related to the accumulation of reactive oxygen species. Our previous studies have found that oxidative stress can activate microtubule affinity-regulating kinases, resulting in elevated phosphorylation levels of tau protein specifically at the Ser262 residue in N1E-115 cells that have been subjected to exposure to hydrogen peroxide. This process may be one of the pathogenic mechanisms of Alzheimer's disease. Vitamin E is a fat-soluble, naturally occurring antioxidant that plays a crucial role in biological systems. This study aimed to examine the probable processes that contribute to the inhibiting effect on the abnormal phosphorylation of tau protein and the neuroprotective activity of a particular type of vitamin E, α-tocotrienol. The experimental analysis revealed that α-tocotrienol showed significant neuroprotective effects in the N1E-115 cell line. Our data further suggest that one of the mechanisms underlying the neuroprotective effects of α-tocotrienol may be through the inhibition of microtubule affinity-regulated kinase activation, which significantly reduces the oxidative stress-induced aberrant elevation of p-Tau (Ser262) levels. These results indicate that α-tocotrienol may represent an intriguing strategy for treating or preventing Alzheimer's disease.

Integrated Bulk and Single-Cell RNA-Sequencing Reveals the Effects of Circadian Rhythm Disruption on the Metabolic Reprogramming of CD4+ T Cells in Alzheimer's Disease

Although growing evidence suggests close correlations between Alzheimer's disease (AD) and circadian rhythm disruption (CRD), few studies have focused on the influence of circadian rhythm on levels of immune cells in AD. We aimed to delineate the mechanism underlying the effects of circadian related genes on T cell immune function in AD. A total of 112 brain samples were used to construct the CRD-related model by performing weighted gene co-expression network analysis and machine learning algorithms (LASSO, SVM-RFE, and RF). The ssGSEA method was used to calculate the CRDscore in order to quantify CRD status. Using single-cell transcriptome data of CSF cells, we investigated the CD4+ T cell metabolism and cell-cell communication in high- and low-risk CRD groups. Connectivity map (CMap) was applied to explore small molecule drugs targeting CRD, and the expression of the signature gene GPR4 was further validated in AD. The CRDscore algorithm, which is based on 23 circadian-related genes, can effectively classify the CRD status in AD datasets. The single-cell analysis revealed that the CD4+ T cells with high CRDscore were characterized by hypometabolism. Cell communication analysis revealed that CD4+ T cells might be involved in promoting CD8+ T cell adhesion under CRD, which may facilitate T cell infiltration into the brain parenchyma. Overall, this study indicates the potential connotation of circadian rhythm in AD, providing insights into understanding T cell metabolic reprogramming under CRD.

CaM-dependent modulation of human CaV1.3 whole-cell and single-channel currents by C-terminal CaMKII phosphorylation site S1475

Phosphorylation enables rapid modulation of voltage-gated calcium channels (VGCC) in physiological and pathophysiological conditions. How phosphorylation modulates human CaV1.3 VGCC, however, is largely unexplored. We characterized modulation of CaV1.3 gating via S1475, the human equivalent of a phosphorylation site identified in the rat. S1475 is highly conserved in CaV1.3 but absent from all other high-voltage activating calcium channel types co-expressed with CaV1.3 in similar tissues. Further, it is located in the C-terminal EF-hand motif, which binds calmodulin (CaM). This is involved in calcium-dependent channel inactivation (CDI). We used amino acid exchanges that mimic either sustained phosphorylation (S1475D) or phosphorylation resistance (S1475A). Whole-cell and single-channel recordings of phosphorylation state imitating CaV1.3 variants in transiently transfected HEK-293 cells revealed functional relevance of S1475 in human CaV1.3. We obtained three main findings: (1) CaV1.3_S1475D, imitating sustained phosphorylation, displayed decreased current density, reduced CDI and (in-) activation kinetics shifted to more depolarized voltages compared with both wildtype CaV1.3 and the phosphorylation-resistant CaV1.3_S1475A variant. Corresponding to the decreased current density, we find a reduced open probability of CaV1.3_S1475D at the single-channel level. (2) Using CaM overexpression or depletion, we find that CaM is necessary for modulating CaV1.3 through S1475. (3) CaMKII activation led to CaV1.3_WT-current properties similar to those of CaV1.3_S1475D, but did not affect CaV1.3_S1475A, confirming that CaMKII modulates human CaV1.3 via S1475. Given the physiological and pathophysiological importance of CaV1.3, our findings on the S1475-mediated interplay of phosphorylation, CaM interaction and CDI provide hints for approaches on specific CaV1.3 modulation under physiological and pathophysiological conditions. KEY POINTS: Phosphorylation modulates activity of voltage-gated L-type calcium channels for specific cellular needs but is largely unexplored for human CaV1.3 channels. Here we report that S1475, a CaMKII phosphorylation site identified in rats, is functionally relevant in human CaV1.3. Imitating phosphorylation states at S1475 alters current density and inactivation in a calmodulin-dependent manner. In wildtype CaV1.3 but not in the phosphorylation-resistant variant S1475A, CaMKII activation elicits effects similar to constitutively mimicking phosphorylation at S1475. Our findings provide novel insights on the interplay of modulatory mechanisms of human CaV1.3 channels, and present a possible target for CaV1.3-specific gating modulation in physiological and pathophysiological conditions.

Dopamine biases decisions by limiting temporal integration

Motivations bias our responses to stimuli, producing behavioural outcomes that match our needs and goals. Here we describe a mechanism behind this phenomenon: adjusting the time over which stimulus-derived information is permitted to accumulate towards a decision. As a Drosophila copulation progresses, the male becomes less likely to continue mating through challenges1-3. We show that a set of copulation decision neurons (CDNs) flexibly integrates information about competing drives to mediate this decision. Early in mating, dopamine signalling restricts CDN integration time by potentiating Ca2+/calmodulin-dependent protein kinase II (CaMKII) activation in response to stimulatory inputs, imposing a high threshold for changing behaviours. Later into mating, the timescale over which the CDNs integrate termination-promoting information expands, increasing the likelihood of switching behaviours. We suggest scalable windows of temporal integration at dedicated circuit nodes as a key but underappreciated variable in state-based decision-making.

Intranasal Delivery of Near-Infrared and Magnetic Dual-Response Nanospheres to Rapidly Produce Antidepressant-Like and Cognitive Enhancement Effects

Restricted by synaptic plasticity, dopamine receptor (DR) upregulation takes a long time to work. Moreover, the impact of the blood-brain barrier (BBB) on delivery efficiency restricts the development of drugs. Taking inspiration from snuff bottles, a convenient, fast-acting, and nonaddictive nasal drug delivery system has been developed to rapidly reshape the balance of synaptic transmitters. This optical and magnetic response system called CFs@DP, comprised of carbonized MIL-100 (Fe) frameworks (CFs) and domperidone (DP), which can enter the brain via nasal administration. Under dual stimulation of near-infrared (NIR) irradiation and catecholamine-induced complexation, CFs@DP disintegrates to release iron ions and DP, causing upregulation of the dopamine type 1 (D1), type 2 (D2) receptors, and brain-derived neurotrophic factor (BDNF) to achieve a therapeutic effect. In vivo experiments demonstrate that the DR density of mice (postnatal day 50-60) increased in the prefrontal cortex (PFC) and the hippocampus (HPC) after 10 days of therapy, resulting in antidepressant-like and cognitive enhancement effects. Interestingly, the cognitive enhancement effect of CFs@DP is even working in noniron deficiency (normal fed) mice, making it a promising candidate for application in enhancing learning ability.

Single-cell discovery of m6A RNA modifications in the hippocampus

N 6-Methyladenosine (m6A) is a prevalent and highly regulated RNA modification essential for RNA metabolism and normal brain function. It is particularly important in the hippocampus, where m6A is implicated in neurogenesis and learning. Although extensively studied, its presence in specific cell types remains poorly understood. We investigated m6A in the hippocampus at a single-cell resolution, revealing a comprehensive landscape of m6A modifications within individual cells. Through our analysis, we uncovered transcripts exhibiting a dense m6A profile, notably linked to neurological disorders such as Alzheimer's disease. Our findings suggest a pivotal role of m6A-containing transcripts, particularly in the context of CAMK2A neurons. Overall, this work provides new insights into the molecular mechanisms underlying hippocampal physiology and lays the foundation for future studies investigating the dynamic nature of m6A RNA methylation in the healthy and diseased brain.

Transcriptional dynamics orchestrating the development and integration of neurons born in the adult hippocampus

The adult hippocampus generates new granule cells (aGCs) with functional capabilities that convey unique forms of plasticity to the preexisting circuits. While early differentiation of adult radial glia-like cells (RGLs) has been studied extensively, the molecular mechanisms guiding the maturation of postmitotic neurons remain unknown. Here, we used a precise birthdating strategy to study aGC differentiation using single-nuclei RNA sequencing. Transcriptional profiling revealed a continuous trajectory from RGLs to mature aGCs, with multiple immature stages bearing increasing levels of effector genes supporting growth, excitability, and synaptogenesis. Analysis of differential gene expression, pseudo-time trajectory, and transcription factors (TFs) revealed critical transitions defining four cellular states: quiescent RGLs, proliferative progenitors, immature aGCs, and mature aGCs. Becoming mature aGCs involved a transcriptional switch that shuts down pathways promoting cell growth, such SoxC TFs, to activate programs that likely control neuronal homeostasis. aGCs overexpressing Sox4 or Sox11 remained immature. Our results unveil precise molecular mechanisms driving adult RGLs through the pathway of neuronal differentiation.

Ketamine alleviates NMDA receptor hypofunction through synaptic trapping

Activity-dependent modulations of N-methyl-D-aspartate glutamate receptor (NMDAR) trapping at synapses regulate excitatory neurotransmission and shape cognitive functions. Although NMDAR synaptic destabilization has been associated with severe neurological and psychiatric conditions, tuning NMDAR synaptic trapping to assess its clinical relevance for the treatment of brain conditions remains a challenge. Here, we report that ketamine (KET) and other clinically relevant NMDAR open channel blockers (OCBs) promote interactions between NMDAR and PDZ-domain-containing scaffolding proteins and enhance NMDAR trapping at synapses. We further show that KET-elicited trapping enhancement compensates for depletion in synaptic receptors triggered by autoantibodies from patients with anti-NMDAR encephalitis. Preventing synaptic depletion mitigates impairments in NMDAR-mediated CaMKII signaling and alleviates anxiety- and sensorimotor-gating-related behavioral deficits provoked by autoantibodies. Altogether, these findings reveal an unexpected dimension of OCB action and stress the potential of targeting receptor anchoring in NMDAR-related synaptopathies.

Binding-induced lipid domains: Peptide-membrane interactions with PIP2 and PS

Cell signaling is an important process involving complex interactions between lipids and proteins. The myristoylated alanine-rich C-kinase substrate (MARCKS) has been established as a key signaling regulator, serving a range of biological roles. Its effector domain (ED), which anchors the protein to the plasma membrane, induces domain formation in membranes containing phosphatidylinositol 4,5-bisphosphate (PIP2) and phosphatidylserine (PS). The mechanisms governing the MARCKS-ED binding to membranes remain elusive. Here, we investigate the composition-dependent affinity and MARCKS-ED-binding-induced changes in interfacial environments using two-dimensional infrared spectroscopy and fluorescence anisotropy. Both negatively charged lipids facilitate the MARCKS-ED binding to lipid vesicles. Although the hydrogen-bonding structure at the lipid-water interface remains comparable across vesicles with varied lipid compositions, the dynamics of interfacial water show divergent patterns due to specific interactions between lipids and peptides. Our findings also reveal that PIP2 becomes sequestered by bound peptides, while the distribution of PS exhibits no discernible change upon peptide binding. Interestingly, PIP2 and PS become colocalized into domains both in the presence and absence of MARCKS-ED. More broadly, this work offers molecular insights into the effects of membrane composition on binding.

Rem2 interacts with CaMKII at synapses and restricts long-term potentiation in hippocampus

Synaptic plasticity, the process whereby neuronal connections are either strengthened or weakened in response to stereotyped forms of stimulation, is widely believed to represent the molecular mechanism that underlies learning and memory. The holoenzyme calcium/calmodulin-dependent protein kinase II (CaMKII) plays a well-established and critical role in the induction of a variety of forms of synaptic plasticity such as long-term potentiation (LTP), long-term depression (LTD) and depotentiation. Previously, we identified the GTPase Rem2 as a potent, endogenous inhibitor of CaMKII. Here, we report that knock out of Rem2 enhances LTP at the Schaffer collateral to CA1 synapse in hippocampus, consistent with an inhibitory action of Rem2 on CaMKII in vivo. Further, re-expression of WT Rem2 rescues the enhanced LTP observed in slices obtained from Rem2 conditional knock out (cKO) mice, while expression of a mutant Rem2 construct that is unable to inhibit CaMKII in vitro fails to rescue increased LTP. In addition, we demonstrate that CaMKII and Rem2 interact in dendritic spines using a 2pFLIM-FRET approach. Taken together, our data lead us to propose that Rem2 serves as a brake on synaptic potentiation via inhibition of CaMKII activity. Further, the enhanced LTP phenotype we observe in Rem2 cKO slices reveals a previously unknown role for Rem2 in the negative regulation of CaMKII function.

Induction of LTP mechanisms in dually innervated dendritic spines

Dendritic spines are the postsynaptic compartments of excitatory synapses, however, a substantial subset of spines additionally receives inhibitory input. In such dually innervated spines (DiSs), excitatory long-term potentiation (LTP) mechanisms are suppressed, but can be enabled by blocking tonic inhibitory GABAB receptor signaling. Here we show that LTP mechanisms at DiSs are also enabled by two other excitatory LTP stimuli. In hippocampal neurons, these chemical LTP (cLTP) stimuli induced robust movement of the Ca2+/calmodulin-dependent protein kinase II (CaMKII) to DiSs. Such synaptic CaMKII accumulation is an essential LTP mechanism at singly innervated spines (SiSs). Indeed, CaMKII accumulation at DiSs was also accompanied by other readouts for successful LTP induction: spine growth and surface insertion of GluA1. Thus, DiSs are capable of the same LTP mechanisms as SiSs, although induction of these mechanism additionally requires either reduced inhibitory signaling or increased excitatory stimulation. This additional regulation may provide further computational control.

Half a century legacy of long-term potentiation

In 1973, two papers from Bliss and Lømo and from Bliss and Gardner-Medwin reported that high-frequency synaptic stimulation in the dentate gyrus of rabbits resulted in a long-lasting increase in synaptic strength. This form of synaptic plasticity, commonly referred to as long-term potentiation (LTP), was immediately considered as an attractive mechanism accounting for the ability of the brain to store information. In this historical piece looking back over the past 50 years, we discuss how these two landmark contributions directly motivated a colossal research effort and detail some of the resulting milestones that have shaped our evolving understanding of the molecular and cellular underpinnings of LTP. We highlight the main features of LTP, cover key experiments that defined its induction and expression mechanisms, and outline the evidence supporting a potential role of LTP in learning and memory. We also briefly explore some ramifications of LTP on network stability, consider current limitations of LTP as a model of associative memory, and entertain future research orientations.

Preventive effect of propolis on cognitive decline in Alzheimer's disease model mice

Brazilian green propolis (propolis) is a chemically complex resinous substance that is a potentially viable therapeutic agent for Alzheimer's disease. Herein, propolis induced a transient increase in intracellular Ca2+ concentration ([Ca2+]i) in Neuro-2A cells; moreover, propolis-induced [Ca2+]i elevations were suppressed prior to 24-h pretreatment with amyloid-β. To reveal the effect of [Ca2+]i elevation on impaired cognition, we performed memory-related behavioral tasks in APP-KI mice relative to WT mice at 4 and 12 months of age. Propolis, at 300-1000 mg/kg/d for 8 wk, significantly ameliorated cognitive deficits in APP-KI mice at 4 months, but not at 12 months of age. Consistent with behavioral observations, injured hippocampal long-term potentiation was markedly ameliorated in APP-KI mice at 4 months of age following repeated propolis administration. In addition, repeated administration of propolis significantly activated intracellular calcium signaling pathway in the CA1 region of APP-KI mice. These results suggest a preventive effect of propolis on cognitive decline through the activation of intracellular calcium signaling pathways in CA1 region of AD mice model.

Tuning synaptic strength by regulation of AMPA glutamate receptor localization

Long-term potentiation (LTP) of excitatory synapses is a leading model to explain the concept of information storage in the brain. Multiple mechanisms contribute to LTP, but central amongst them is an increased sensitivity of the postsynaptic membrane to neurotransmitter release. This sensitivity is predominantly determined by the abundance and localization of AMPA-type glutamate receptors (AMPARs). A combination of AMPAR structural data, super-resolution imaging of excitatory synapses, and an abundance of electrophysiological studies are providing an ever-clearer picture of how AMPARs are recruited and organized at synaptic junctions. Here, we review the latest insights into this process, and discuss how both cytoplasmic and extracellular receptor elements cooperate to tune the AMPAR response at the hippocampal CA1 synapse.

Unraveling the enigma: Molecular mechanisms of berberrubine-induced nephrotoxicity reversed by its parent form berberine

BACKGROUND

Berberine is an isoquinoline alkaloid that is extensively applied in the clinic due to its potential therapeutic effects on dysentery and infectious diarrhoea. Its main metabolite, berberrubine, a promising candidate for ameliorating hyperlipidaemia, has garnered more attention than berberine. However, our study revealed that berberrubine induces severe kidney damage, while berberine was proven to be safe.

PURPOSE

Herein, we explored the opposite biological effects of these two compounds on the kidney and elucidated their underlying mechanisms.

METHODS

First, integrated metabolomic and proteomic analyses were conducted to identify relevant signalling pathways. Second, a click chemistry method combined with a cellular thermal shiftassay, a drug affinity responsive target stability assay, and microscale thermophoresis were used to identify the direct target proteins. Moreover, a mutation experiment was performed to study the specific binding sites.

RESULTS

Animal studies showed that berberrubine, but not berberine, induced severe chronic, subchronic, and acute nephrotoxicity. More importantly, berberine reversed the berberrubine-reduced nephrotoxicity. The results indicated that the cPLA2 signalling pathway was highly involved in the nephrotoxicity induced by berberrubine. We further confirmed that the direct target of berberrubine is the BASP1 protein (an upstream factor of cPLA2 signalling). Moreover, berberine alleviated nephrotoxicity by binding cPLA2 and inhibiting cPLA2 activation.

CONCLUSION

This study is the first to revel the opposite biological effects of berberine and its metabolite berberrubine in inducing kidney injury. Berberrubine, but not berberine, shows strong nephrotoxicity. The cPLA2 signalling pathway can be activated by berberrubine through targeting of BASP1, while berberine inhibits this pathway by directly binding with cPLA2. Our study paves the way for studies on the exact molecular targets of herbal ingredients. We also demonstrated that natural small molecules and their active metabolites can have opposite regulatory roles in vivo through the same signalling pathway.

KIBRA anchoring the action of PKMζ maintains the persistence of memory

How can short-lived molecules selectively maintain the potentiation of activated synapses to sustain long-term memory? Here, we find kidney and brain expressed adaptor protein (KIBRA), a postsynaptic scaffolding protein genetically linked to human memory performance, complexes with protein kinase Mzeta (PKMζ), anchoring the kinase's potentiating action to maintain late-phase long-term potentiation (late-LTP) at activated synapses. Two structurally distinct antagonists of KIBRA-PKMζ dimerization disrupt established late-LTP and long-term spatial memory, yet neither measurably affects basal synaptic transmission. Neither antagonist affects PKMζ-independent LTP or memory that are maintained by compensating PKCs in ζ-knockout mice; thus, both agents require PKMζ for their effect. KIBRA-PKMζ complexes maintain 1-month-old memory despite PKMζ turnover. Therefore, it is not PKMζ alone, nor KIBRA alone, but the continual interaction between the two that maintains late-LTP and long-term memory.

CaMKII autophosphorylation is the only enzymatic event required for synaptic memory

Ca2+/calmodulin (CaM)-dependent kinase II (CaMKII) plays a critical role in long-term potentiation (LTP), a well-established model for learning and memory through the enhancement of synaptic transmission. Biochemical studies indicate that CaMKII catalyzes a phosphotransferase (kinase) reaction of both itself (autophosphorylation) and of multiple downstream target proteins. However, whether either type of phosphorylation plays any role in the synaptic enhancing action of CaMKII remains hotly contested. We have designed a series of experiments to define the minimal requirements for the synaptic enhancement by CaMKII. We find that autophosphorylation of T286 and further binding of CaMKII to the GluN2B subunit are required both for initiating LTP and for its maintenance (synaptic memory). Once bound to the NMDA receptor, the synaptic action of CaMKII occurs in the absence of target protein phosphorylation. Thus, autophosphorylation and binding to the GluN2B subunit are the only two requirements for CaMKII in synaptic memory.

Expression of GAD2 in excitatory neurons projecting from the ventrolateral periaqueductal gray to the locus coeruleus

The ventrolateral periaqueductal gray (vlPAG) functionally projects to diverse brain regions, including the locus coeruleus (LC). Excitatory projections from the vlPAG to the LC are well described, while few studies have indicated the possibility of inhibitory projections. Here, we quantified the relative proportion of excitatory and inhibitory vlPAG-LC projections in male and female mice, and found an unexpected overlapping population of neurons expressing both GAD2 and VGLUT2. Combined in vitro optogenetic stimulation and electrophysiology of LC neurons revealed that vlPAG neurons expressing channelrhodopsin-2 under the GAD2 promoter release both GABA and glutamate. Subsequent experiments identified a population of GAD2+/VGLUT2+ vlPAG neurons exclusively releasing glutamate onto LC neurons. Altogether, we demonstrate that ∼25% of vlPAG-LC projections are inhibitory, and that there is a significant GAD2 expressing population of glutamatergic projections. Our findings have broad implications for the utility of GAD2-Cre lines within midbrain and brainstem regions, and especially within the PAG.

Interaction of the Melatonin/Ca2+-CaM Complex with Calmodulin Kinase II: Physiological Importance

Melatonin N-acetyl-5-methoxytriptamine is an ancient molecule which synchronizes the internal biologic activity with the environmental photoperiod. It is synthesized by the pineal gland during the night and released to the general circulation, where it reaches nanomolar concentrations. The indolamine acts through melatonin receptors and binds to different proteins such as calmodulin: a phylogenetically conserved protein which is the main transductor of the calcium signaling. In this review, we will describe evidence supporting that melatonin binds to calmodulin in presence of calcium, and we discuss the effects of this indolamine on the activity of calmodulin kinase II as an inhibitor and as stimulator of calmodulin-dependent protein kinase II activity. We also provide a literature review supporting the relevance of melatonin binding to calmodulin in the regulation of circadian rhythms in unicellular organisms, as well as in neuronal development in mammals as an ancient, conserved mechanism. Finally, we highlight the importance of antioxidant effects of melatonin on calmodulin preservation. SIGNIFICANCE STATEMENT: This review compiled evidence supporting that melatonin binds to calmodulin. We discuss the dual effect of melatonin on the activity of calmodulin kinase II, the possible mechanisms involved, and the relevance on regulation of circadian rhythms and neurodevelopment. Finally, we describe evidence supporting that the binding of melatonin to calmodulin hydrophobic pockets may prevent the oxidation of methionine species with a shielding effect that preserves the functionality of calmodulin.

Effects of Interleukin-19 overexpression in the medial prefrontal cortex on anxiety-related behaviors, BDNF expression and p38/JNK/ERK pathways

Anxiety is a prevalent mental illness known for its high incidence, comorbidity, and tendency to recur, posing significant societal and individual burdens. Studies have highlighted Interleukin-19 (IL-19) as having potential relevance in neuropsychiatric disorders. Our previous research revealed that IL-19 overexpression in colonies exacerbated anxiety-related behaviors induced by dextran sodium sulfate/stress. However, the precise role and molecular mechanisms of IL-19 in anxiety regulation remain uncertain. In this study, we initiated an acute restraint stress (ARS)-induced anxious mouse model and identified heightened expression of IL-19 and IL-20Rα in the medial prefrontal cortex (mPFC) of ARS mice. Notably, IL-19 and IL-20Rα were predominantly present in the excitatory pyramidal neurons of the mPFC under both basal and ARS conditions. Utilizing the adeno-associated virus (AAV) strategy, we demonstrated that IL-19 overexpression in the mPFC induced anxiety-related behaviors and elevated stress susceptibility. Additionally, we observed decreased protein levels of brain-derived neurotrophic factor (BDNF) and postsynaptic density protein 95 (PSD95) in the mPFC of IL-19 overexpression mice, accompanied by reduced phosphorylation of in the p38, JNK, and Erk signaling pathways. These findings emphasize the role of IL-19 in modulating anxiety-related behaviors within the mPFC and suggest its potential as a pathological gene and therapeutic target for anxiety.

Monomeric pilose antler peptide improves depression-like behavior in mice by inhibiting FGFR3 protein expression

ETHNOPHARMACOLOGICAL RELEVANCE

It has been found that pilose antler peptide has an antidepressant effect on depression. However, the exact molecular mechanism of its antidepressant effect is still unclear.

AIM OF THE STUDY

The study sought to determine the impact of monomeric pilose antler peptide (PAP; sequence LVLVEAELRE) on depression as well as investigate potential molecular mechanisms.

MATERIALS AND METHODS

Chronic unexpected mild stress (CUMS) was used to establish the model, and the effect of PAP on CUMS mice was detected by the behavioral test. The influence of PAP on neuronal cells and dendritic spine density was observed by immunofluorescence and Golgi staining. FGFR3 and the CaMKII-associated pathway were identified using quantitative real-time polymerase chain reaction, and Western blot analysis was utilized to measure their proteins and gene expression levels. Molecular docking and microscale thermophoresis were applied to detect the binding of PAP and FGFR3. Finally, the effect of FGFR3's overexpression on PAP treatment of depression was detected.

RESULTS

PAP alleviated the changes in depressive behavior induced by CUMS, promoted the growth of nerve cells, and the density of dendritic spines was increased to its original state. PAP therapy successfully downregulated the expression of FGFR3 and ERK1/2 while upregulating the expression of CREB, BDNF, and CaMKII.

CONCLUSION

Based on the current research, PAP has a therapeutic effect on depression brought on by CUMS by inhibiting FGFR3 expression and enhancing synaptic plasticity.

SIRT1 mediates the excitability of spinal CaMKIIα-positive neurons and participates in neuropathic pain by controlling Nav1.3

AIMS

Neuropathic pain is a common chronic pain disorder, which is largely attributed to spinal central sensitization. Calcium/calmodulin-dependent protein kinase II alpha (CaMKIIα) activation in the spinal dorsal horn (SDH) is a major contributor to spinal sensitization. However, the exact way that CaMKIIα-positive (CaMKIIα+) neurons in the SDH induce neuropathic pain is still unclear. This study aimed to explore the role of spinal CaMKIIα+ neurons in neuropathic pain caused by chronic constriction injury (CCI) and investigate the potential epigenetic mechanisms involved in CaMKIIα+ neuron activation.

METHODS

CCI-induced neuropathic pain mice model, Sirt1loxP/loxP mice, and chemogenetic virus were used to investigate whether the activation of spinal CaMKIIα+ neurons is involved in neuropathic pain and its involved mechanism. Transcriptome sequence, western blotting, qRT-PCR, and immunofluorescence analysis were performed to assay the expression of related molecules and activation of neurons. Co-immunoprecipitation was used to observe the binding relationship of protein. Chromatin immunoprecipitation (ChIP)-PCR was applied to analyze the acetylation of histone H3 in the Scn3a promoter region.

RESULTS

The expression of sodium channel Nav1.3 was increased and the expression of SIRT1 was decreased in the spinal CaMKIIα+ neurons of CCI mice. CaMKIIα neurons became overactive after CCI, and inhibiting their activation relieved CCI-induced pain. Overexpression of SIRT1 reversed the increase of Nav1.3 and alleviated pain, while knockdown of SIRT1 or overexpression of Nav1.3 promoted CaMKIIα+ neuron activation and induced pain. By knocking down spinal SIRT1, the acetylation of histone H3 in the Scn3a (encoding Nav1.3) promoter region was increased, leading to an increased expression of Nav1.3.

CONCLUSION

The findings suggest that an aberrant reduction of spinal SIRT1 after nerve injury epigenetically increases Nav1.3, subsequently activating CaMKIIα+ neurons and causing neuropathic pain.

A synapse-specific refractory period for plasticity at individual dendritic spines

How newly formed memories are preserved while brain plasticity is ongoing has been a source of debate. One idea is that synapses which experienced recent plasticity become resistant to further plasticity, a type of metaplasticity often referred to as saturation. Here, we probe the local dendritic mechanisms that limit plasticity at recently potentiated synapses. We show that recently potentiated individual synapses exhibit a synapse-specific refractory period for further potentiation. We further found that the refractory period is associated with reduced postsynaptic CaMKII signaling; however, stronger synaptic activation only partially restored the ability for further plasticity. Importantly, the refractory period is released after one hour, a timing that coincides with the enrichment of several postsynaptic proteins to pre-plasticity levels. Notably, increasing the level of the postsynaptic scaffolding protein, PSD95, but not of PSD93, overcomes the refractory period. Our results support a model in which potentiation at a single synapse is sufficient to initiate a synapse-specific refractory period that persists until key postsynaptic proteins regain their steady-state synaptic levels.

In vivo cyclic overexpression of Yamanaka factors restricted to neurons reverses age-associated phenotypes and enhances memory performance

In recent years, there has been success in partially reprogramming peripheral organ cells using cyclic Yamanaka transcription factor (YF) expression, resulting in the reversal of age-related pathologies. In the case of the brain, the effects of partial reprogramming are scarcely known, and only some of its effects have been observed through the widespread expression of YF. This study is the first to exclusively partially reprogram a specific subpopulation of neurons in the cerebral cortex of aged mice. The in vivo model demonstrate that YF expression in postmitotic neurons does not dedifferentiate them, and it avoids deleterious effects observed with YF expression in other cell types. Additionally, our study demonstrates that only cyclic, not continuous, expression of YF result in a noteworthy enhancement of cognitive function in adult mice. This enhancement is closely tied to increased neuronal activation in regions related to memory processes, reversed aging-related epigenetic markers and to increased plasticity, induced by the reorganization of the extracellular matrix. These findings support the therapeutic potential of targeted partial reprogramming of neurons in addressing age-associated phenotypes and neurodegenerative diseases correlated with aging.

Deletion of CaMKIIα disrupts glucose metabolism, glutamate uptake, and synaptic energetics in the cerebral cortex

Ca2+/calmodulin-dependent protein kinase II alpha (CaMKIIα) is a key regulator of neuronal signaling and synaptic plasticity. Synaptic activity and neurotransmitter homeostasis are closely coupled to the energy metabolism of both neurons and astrocytes. However, whether CaMKIIα function is implicated in brain energy and neurotransmitter metabolism remains unclear. Here, we explored the metabolic consequences of CaMKIIα deletion in the cerebral cortex using a genetic CaMKIIα knockout (KO) mouse. Energy and neurotransmitter metabolism was functionally investigated in acutely isolated cerebral cortical slices using stable 13C isotope tracing, whereas the metabolic function of synaptosomes was assessed by the rates of glycolytic activity and mitochondrial respiration. The oxidative metabolism of [U-13C]glucose was extensively reduced in cerebral cortical slices of the CaMKIIα KO mice. In contrast, metabolism of [1,2-13C]acetate, primarily reflecting astrocyte metabolism, was unaffected. Cellular uptake, and subsequent metabolism, of [U-13C]glutamate was decreased in cerebral cortical slices of CaMKIIα KO mice, whereas uptake and metabolism of [U-13C]GABA were unaffected, suggesting selective metabolic impairments of the excitatory system. Synaptic metabolic function was maintained during resting conditions in isolated synaptosomes from CaMKIIα KO mice, but both the glycolytic and mitochondrial capacities became insufficient when the synaptosomes were metabolically challenged. Collectively, this study shows that global deletion of CaMKIIα significantly impairs cellular energy and neurotransmitter metabolism, particularly of neurons, suggesting a metabolic role of CaMKIIα signaling in the brain.

RIPK3 promotes neuronal survival by suppressing excitatory neurotransmission during CNS viral infection

While recent work has identified roles for immune mediators in the regulation of neural activity, the capacity for cell intrinsic innate immune signaling within neurons to influence neurotransmission remains poorly understood. However, the existing evidence linking immune signaling with neuronal function suggests that modulation of neurotransmission may serve previously undefined roles in host protection during infection of the central nervous system. Here, we identify a specialized function for RIPK3, a kinase traditionally associated with necroptotic cell death, in preserving neuronal survival during neurotropic flavivirus infection through the suppression of excitatory neurotransmission. We show that RIPK3 coordinates transcriptomic changes in neurons that suppress neuronal glutamate signaling, thereby desensitizing neurons to excitotoxic cell death. These effects occur independently of the traditional functions of RIPK3 in promoting necroptosis and inflammatory transcription. Instead, RIPK3 promotes phosphorylation of the key neuronal regulatory kinase CaMKII, which in turn activates the transcription factor CREB to drive a neuroprotective transcriptional program and suppress deleterious glutamatergic signaling. These findings identify an unexpected function for a canonical cell death protein in promoting neuronal survival during viral infection through the modulation of neuronal activity, highlighting new mechanisms of neuroimmune crosstalk.

Studying CaMKII: Tools and standards

The Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) is a ubiquitous mediator of cellular Ca2+ signals with both enzymatic and structural functions. Here, we briefly introduce the complex regulation of CaMKII and then provide a comprehensive overview of the expanding toolbox to study CaMKII. Beyond a variety of distinct mutants, these tools now include optical methods for measurement and manipulation, with the latter including light-induced inhibition, stimulation, and sequestration. Perhaps most importantly, there are now three mechanistically distinct classes of specific CaMKII inhibitors, and their combined use enables the interrogation of CaMKII functions in a manner that is powerful and sophisticated yet also accessible. This review aims to provide guidelines for the interpretation of the results obtained with these tools, with careful consideration of their direct and indirect effects.

Rapid sequential clustering of NMDARs, CaMKII, and AMPARs upon activation of NMDARs at developing synapses

Rapid, synapse-specific neurotransmission requires the precise alignment of presynaptic neurotransmitter release and postsynaptic receptors. How postsynaptic glutamate receptor accumulation is induced during maturation is not well understood. We find that in cultures of dissociated hippocampal neurons at 11 days in vitro (DIV) numerous synaptic contacts already exhibit pronounced accumulations of the pre- and postsynaptic markers synaptotagmin, synaptophysin, synapsin, bassoon, VGluT1, PSD-95, and Shank. The presence of an initial set of AMPARs and NMDARs is indicated by miniature excitatory postsynaptic currents (mEPSCs). However, AMPAR and NMDAR immunostainings reveal rather smooth distributions throughout dendrites and synaptic enrichment is not obvious. We found that brief periods of Ca2+ influx through NMDARs induced a surprisingly rapid accumulation of NMDARs within 1 min, followed by accumulation of CaMKII and then AMPARs within 2-5 min. Postsynaptic clustering of NMDARs and AMPARs was paralleled by an increase in their mEPSC amplitudes. A peptide that blocked the interaction of NMDAR subunits with PSD-95 prevented the NMDAR clustering. NMDAR clustering persisted for 3 days indicating that brief periods of elevated glutamate fosters permanent accumulation of NMDARs at postsynaptic sites in maturing synapses. These data support the model that strong glutamatergic stimulation of immature glutamatergic synapses results in a fast and substantial increase in postsynaptic NMDAR content that required NMDAR binding to PSD-95 or its homologues and is followed by recruitment of CaMKII and subsequently AMPARs.

Thymol as a Potential Neuroprotective Agent: Mechanisms, Efficacy, and Future Prospects

Neurodegenerative diseases pose a growing global health challenge, with limited effective therapeutic options. Mitochondrial dysfunction, oxidative stress, neuroinflammation, apoptosis, and autophagy are common underlying mechanisms in these diseases. Thymol is a phenolic monoterpene compound that has gained attention for its diverse biological properties, including antioxidant, anti-inflammatory, and immunomodulatory activities. Thymol supplementation could provide potential neuroprotection and improve cognitive deficits, depressant-like effects, learning, and memory impairments in rodents. Mechanistic investigations reveal that the neuroprotective effects of thymol involve the improvement of oxidative stress, mitochondrial dysfunction, and inflammatory response. Several signaling pathways, including mitochondrial apoptotic, NF-κB, AKT, Nrf2, and CREB/BDNF pathways are also involved. In this review, the neuroprotective effects of thymol, the potential molecular mechanisms, safety, applications, and current challenges toward development as a neuroprotective agent were summarized and discussed. We hope that this review provides valuable insights for the further development of this promising natural product as a promising neuroprotective agent.

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.