Synaptic memory and CaMKII

Neurotransmitter imbalance and amygdala synaptic plasticity in lumbar disc herniation-induced chronic pain and related emotional Disturbances:A multi-omics analysis

Chronic pain due to lumbar disc herniation (LDH) significantly impairs quality of life and is often accompanied by emotional disturbances, such as anxiety and depression. Despite the recognition of these comorbidities, the underlying neural mechanisms remain unclear. This study investigates the role of neurotransmitter imbalances and key regulatory molecules in LDH-induced chronic pain and related emotional disturbances, with a focus on synaptic plasticity in the amygdala. A rat model of LDH was developed using male Sprague-Dawley rats. Behavioral assessments were conducted to evaluate pain hypersensitivity, anxiety, and depression-like behaviors. Cerebrospinal fluid (CSF) metabolomics and amygdala transcriptomics were employed to analyze neurotransmitter profiles and gene expression. In vitro experiments were conducted to explore the role of PRKCG in synaptic plasticity. Behavioral tests showed significant pain hypersensitivity and anxiety- and depression-like behavior in LDH rats. Metabolomic analysis revealed altered levels of glutamate and γ-aminobutyric acid (GABA) in the CSF, indicating neurotransmitter imbalances. Transcriptomic profiling identified changes in genes related to synaptic plasticity, including PRKCG. PRKCG knockdown led to reduced CAMKII phosphorylation and GRIA1 expression, supporting its role in modulating synaptic plasticity. This study provides evidence that neurotransmitter imbalances and alterations in synaptic plasticity within the amygdala may contribute to the persistence of chronic pain and associated emotional disturbances in LDH. PRKCG may represent a novel therapeutic target for treating both chronic pain and related emotional disturbances.

FMRP Controls Neuronal Architecture and Synaptic Content of NMDA Receptors in Cultured Hippocampal Neurons

Fragile X syndrome is the most common inherited form of intellectual disability and is caused by the transcriptional silencing of the Fmr1 gene and the lack of fragile X messenger ribonucleoprotein (FMRP). FMRP is an RNA-binding protein that regulates the synthesis of synaptic proteins which are essential for proper brain function. Although circuit hyperexcitability is a hallmark of fragile X syndrome (FXS), the cell-autonomous effects of FMRP deficiency remain poorly understood. In this work, we investigated the functional consequences of the absence of FMRP on neuronal morphology and on ionotropic glutamate receptor surface distribution, using primary cultures of mice hippocampal neurons isolated from wild-type (WT) and Fmr1 knock-out (KO) pups. MAP2 staining of Fmr1 KO neurons showed a decrease in total dendritic length and complexity of the dendritic tree, accompanied by an increase in soma size compared to WT neurons. Moreover, immunolabelling of surface glutamate receptors performed under non-permeabilising conditions showed that Fmr1 KO neurons presented a higher content of synaptic surface GluN2A and a lower content of GluN2B subunits of NMDA receptors, while GluA1 and GluA2 distribution remained unchanged. Finally, multielectrode array data showed that Fmr1 KO neurons presented reduced spontaneous activity compared to control neurons. These data support the hypothesis that at the cellular level, Fmr1 KO hippocampal neurons are less excitable due to altered input processing, driven by structural defects and altered GluN2A expression in the synaptic plasma membrane.

A hyper-activatable CAMK2A variant associated with intellectual disability causes exaggerated long-term potentiation and learning impairments

Intellectual disability (ID) is a neurodevelopmental disorder (NDD) characterized by impairments in intellectual and adaptive functioning, and is highly co-morbid with other NDDs. Recently, de novo missense variants in the gene, CAMK2A, which encodes calcium/calmodulin-dependent protein kinase IIα (CaMKIIα), an abundant neuronal protein crucial for synaptic plasticity, learning and memory, have been implicated in ID. However, the causative impact of these mutations remains underexplored. In this study, we developed a heterozygous knock-in mouse model carrying the most prevalent ID-associated CAMK2A de novo missense variant, P212L, as a gain-of-function allele. The knock-in mice exhibited increased autophosphorylation of CaMKIIα, indicative of exuberant kinase activity, and consistently showed dendritic spine abnormalities and exaggerated hippocampal long-term potentiation induced by a subthreshold low-frequency stimulation. Furthermore, a comprehensive behavioral evaluation, including learning and memory tasks, revealed prominent phenotypes recapitulating the complex clinical phenotypes of humans with ID/NDDs harboring the same variant. Taken together, we propose that aberrant enhancement of CaMKIIα signaling by the heterozygous P212L mutation underlies a subset of ID/NDD features. These findings provide new insights into the pathogenesis of ID/NDDs, specifically through the genetic up-shifting of the critical memory regulator, CaMKII. Additionally, the established mouse model, with both construct and face validity, is expected to significantly contribute to the understanding and future therapeutic development of ID/NDDs.

Increased NaV1.2 expression and its interaction with CaM contribute to the hyperexcitability induced by prolonged inhibition of CaMKII

OBJECTIVE

Dysfunction of calcium/calmodulin (CaM)-dependent kinase II (CaMKII) has been involved in hyperexcitability-related disorders including epilepsy. However, the relationship between CaMKII and neuronal excitability remains unclear.

METHODS

Neuronal excitability was detected in vivo and in vitro by electroencephalography (EEG), patch clamp and multi-electrode array (MEA), respectively. Next, we assessed the currents of voltage-gated sodium channels (VGSCs) by patch clamp, and  mRNA and protein expressions of VGSCs were determined by real-time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blot, respectively. Meanwhile, the association between the nuclear receptor subfamily 4 group A member 2 (NR4A2) and promoters of Scn2a, was determined by chromatin immunoprecipitation (ChIP)-qPCR. In addition, we utilized co-immunoprecipitation (Co-IP), immunofluorescence labeling, and pull-down to determine the interaction between VGSCs and CaM.

RESULTS

Prolonged CaMKII inhibition by KN93, an inhibitor of CaMKII, for 24 h and CaMKII knockdown induced more seizure-like events in Wistar rats, TRM rats and C57BL/6 mice, and led to hyperexcitability in primary hippocampal neurons and human induced-pluripotent stem cell (hiPSC)-derived cortical neurons. In addition, prolonged CaMKII inhibition resulted in elevated persistent sodium current (INaP)/transient sodium current (INaT) and increased mRNA and protein expressions of NaV1.2. Meanwhile, prolonged CaMKII inhibition by KN93 decreased NR4A2 expression and contributed to a transcriptional repression role of NR4A2 in Scn2a regulation, leading to increased NaV1.2 expression. Moreover, an increased interaction between NaV1.2 and CaM was attributable to enhanced binding of CaM to the isoleucine-glutamine (IQ) domain at the C-terminus of the NaV1.2 channel, which may also lead to the potentiation in INaP/INaT and channel activity. Furthermore, a peptide that antagonized CaM binding to NaV1.2 IQ domain (ACNp) rescued hyperexcitability following prolonged CaMKII inhibition.

SIGNIFICANCE

We unveiled that prolonged CaMKII inhibition induced hyperexcitability through increasing the expression of NaV1.2 and its association with CaM. Thus, our study uncovers a novel signaling mechanism by which CaMKII maintains appropriate neuronal excitability.

Molecular and cellular neurocardiology in heart disease

This paper updates and builds on a previous White Paper in this journal that some of us contributed to concerning the molecular and cellular basis of cardiac neurobiology of heart disease. Here we focus on recent findings that underpin cardiac autonomic development, novel intracellular pathways and neuroplasticity. Throughout we highlight unanswered questions and areas of controversy. Whilst some neurochemical pathways are already demonstrating prognostic viability in patients with heart failure, we also discuss the opportunity to better understand sympathetic impairment by using patient specific stem cells that provides pathophysiological contextualization to study 'disease in a dish'. Novel imaging techniques and spatial transcriptomics are also facilitating a road map for target discovery of molecular pathways that may form a therapeutic opportunity to treat cardiac dysautonomia.

Enhancing Retinal Resilience: The Neuroprotective Promise of BDNF in Diabetic Retinopathy

Diabetic retinopathy (DR), a leading cause of vision impairment worldwide, is characterized by progressive damage to the retina due to prolonged hyperglycemia. Despite advances in treatment, current interventions largely target late-stage vascular complications, leaving underlying neurodegenerative processes insufficiently addressed. This article explores the crucial role in neuronal survival, axonal growth, and synaptic plasticity and the neuroprotective potential of Brain-Derived Neurotrophic Factor (BDNF) as a therapeutic strategy for enhancing retinal resilience in DR. Furthermore, it discusses innovative delivery methods for BDNF, such as gene therapy and nanocarriers, which may overcome the challenges of achieving sustained and targeted therapeutic levels in the retina, focusing on early intervention to preserve retinal function and prevent vision loss.

Ca2+/calmodulin signaling in organismal aging and cellular senescence: Impact on human diseases

Molecular mechanisms of aging processes at the level of organisms and cells are in the focus of a large number of research laboratories. This research culminated in recent breakthroughs, which contributed to the better understanding of the natural aging process and aging associated malfunctions leading to age-related diseases. Ca2+ in connection with its master intracellular sensor protein calmodulin (CaM) regulates a plethora of crucial cellular processes orchestrating a wide range of signaling processes. This review focuses on the involvement of Ca2+/CaM in cellular mechanisms, which are associated with normal aging, as well as playing a role in the development of diseases connected with signaling processes during aging. We specifically highlight processes that involve inactivation of proteins, which take part in Ca2+/CaM regulatory systems by oxygen or nitrogen free radical species, during organismal aging and cellular senescence. As examples of organs where aging processes have recently been investigated, we chose to review the literature on molecular aging processes with involvement of Ca2+/CaM in heart and neuronal diseases, as well as in cancer and metabolic diseases, all deeply affected by aging. In addition, this article focuses on cellular senescence, a mechanism that may contribute to aging processes and therefore has been proposed as a target to interfere with the progression of age-associated diseases.

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.

Associative learning and recollection of olfactory memory during the respiratory cycle in mammals: how is the self cognized in consciousness?

When we are awake and relaxed, various memory-scenes come up in our mind by spontaneous activation of memory engrams. We find ourselves in the memory-scene longing for it by the present self. The memory scene is also recollected by sensory inputs from the surrounding world for learned behavioral decisions. It is well experienced that odorants act as strong cues in remembering associated memory. Associative learning of odor signals and object cognition enables us to predict cognitive imagery of an environmental object. Here, we discuss the neural network connecting the olfactory cortices to the higher cognitive areas that dynamically switches the processing mode from feedforward to top-down. These processes are correlated with the respiratory cycle to form and recollect odor-object associative memory. We infer that during the inhalation phase, feedforward odor signals drive burst firings of a specific subset of pyramidal cells in the olfactory cortex. In contrast, during the subsequent late-exhalation phase, top-down cognitive scene-signals from the higher areas activate again the same pyramidal cells as those activated by the feedforward signals. Reactivation of pyramidal cells during the exhalation phase may induce plastic changes in the inter-areal synaptic connections in the neural network to form associative-learning memory. In this perspective article, we will discuss associative learning and cognition of self in the mammalian olfactory system.

Evaluation of allosteric N-methyl-d-aspartate receptor modulation by GluN2A-selective antagonists using pharmacological equilibrium modeling

N-methyl-d-aspartate (NMDA)-type ionotropic glutamate receptors are critically involved in excitatory neurotransmission and their dysfunction is implicated in many brain disorders. Allosteric modulators with selectivity for specific NMDA receptor subtypes are therefore attractive as therapeutic agents, and sustained drug discovery efforts have resulted in a wide range of new allosteric modulators. However, evaluation of allosteric NMDA receptor modulators is limited by the lack of operational ligand-receptor models to describe modulator binding dissociation constants (KB) and effects on agonist binding affinity (α) and efficacy (β). Here, we describe a pharmacological equilibrium model that encapsulates activation and modulation of NMDA receptors, and we apply this model to afford deeper understanding of GluN2A-selective negative allosteric modulators, TCN-201, MPX-004, and MPX-007. We exploit slow negative allosteric modulator unbinding to examine receptors at hemi-equilibrium when fully occupied by agonists and modulators to demonstrate that TCN-201 display weaker binding and negative modulation of glycine binding affinity (KB = 42 nM, α = 0.0032) compared with MPX-004 (KB = 9.3 nM, α = 0.0018) and MPX-007 (KB = 1.1 nM, α = 0.00053). MPX-004 increases agonist efficacy (β = 1.19), whereas TCN-201 (β = 0.76) and MPX-007 (β = 0.82) reduce agonist efficacy. These values describing allosteric modulation of diheteromeric GluN1/2A receptors with 2 modulator binding sites are unchanged in triheteromeric GluN1/2A/2B receptors with a single binding site. This evaluation of NMDA receptor modulation reveals differences between ligand analogs that shape their utility as pharmacological tool compounds and facilitates the design of new modulators with therapeutic potential. SIGNIFICANCE STATEMENT: Detailed understanding of allosteric N-methyl-d-aspartate (NMDA) receptor modulation requires pharmacological methods to quantify modulator binding affinity and the strengths of modulation of agonist binding and efficacy. We describe a generic ligand-receptor model for allosteric NMDA receptor modulation and use this model for the characterization of GluN2A-selective negative allosteric modulators. The model enables quantitative evaluation of a broad range of NMDA receptor modulators and provides opportunities to optimize these modulators by embellishing the interpretation of their structure-activity relationships.

The Biological Changes of Synaptic Plasticity in the Pathological Process of Sepsis-associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a form of cognitive and psychological impairment resulting from sepsis, which occurs without any central nervous system infection or structural brain injury. Patients may experience long-term cognitive deficits and psychiatric disorders even after discharge. However, the underlying mechanism remains unclear. As cognitive function and mental disease are closely related to synaptic plasticity, it is presumed that alterations in synaptic plasticity play an essential role in the pathological process of SAE. Here, we present a systematic description of the pathogenesis of SAE, which is primarily driven by glial cell activation and subsequent release of inflammatory mediators. Additionally, we elucidate the alterations in synaptic plasticity that occur during SAE and comprehensively discuss the roles played by glial cells and inflammatory factors in this process. In this review, we mainly discuss the synaptic plasticity of SAE, and the main aim is to show the consequences of SAE on inflammatory factors and how they affect synaptic plasticity. This review may enhance our understanding of the mechanism underlying cognitive dysfunction and provide valuable insights into identifying appropriate therapeutic targets for SAE.

Ethanol self-administration targets GluA2-containing AMPA receptor expression and synaptic activity in the nucleus accumbens in a manner that drives the positive reinforcing properties of the drug

RATIONALE

The positive reinforcing effects of alcohol (ethanol) drive repetitive use and contribute to alcohol use disorder (AUD). Ethanol alters the expression of glutamate AMPA receptor (AMPAR) subunits in reward-related brain regions, but the extent to which this effect regulates ethanol's reinforcing properties is unclear.

OBJECTIVE

This study investigates whether ethanol self-administration changes AMPAR subunit expression and synaptic activity in the nucleus accumbens core (AcbC) to regulate ethanol's reinforcing effects in male C57BL/6 J mice.

RESULTS

Sucrose-sweetened ethanol self-administration (0.81 g/kg/day) increased AMPAR GluA2 protein expression in the AcbC, without effect on GluA1, compared to sucrose-only controls. Infusion of myristoylated Pep2m in the AcbC, which blocks GluA2 binding to N-ethylmaleimide-sensitive fusion protein (NSF) and reduces GluA2-containing AMPAR activity, reduced ethanol-reinforced responding without affecting sucrose-only self-administration or motor activity. Antagonizing GluA2-lacking AMPARs, through AcbC infusion of NASPM, had no effect on ethanol self-administration. AcbC neurons receiving projections from the basolateral amygdala (BLA) showed increased sEPSC area under the curve (a measurement of charge transfer) and slower decay kinetics in ethanol self-administering mice as compared to sucrose. Optogenetic activation of these neurons revealed an ethanol-enhanced AMPA/NMDA ratio and significantly reduced paired-pulse ratio, suggesting elevated GluA2 contributions specifically within the BLA➔AcbC pathway.

CONCLUSIONS

Ethanol use upregulates GluA2 protein expression in the AcbC and AMPAR synaptic activity in AcbC neurons receiving BLA projections and enhances synaptic plasticity directly within the BLA➔AcbC circuit. GluA2-containing AMPAR activity in the AcbC regulates the positive reinforcing effects of ethanol through an NSF-dependent mechanism, highlighting a potential therapeutic target in AUD.

A spatial model of autophosphorylation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) predicts that the lifetime of phospho-CaMKII after induction of synaptic plasticity is greatly prolonged by CaM-trapping

Long-term potentiation (LTP) is a biochemical process that underlies learning in excitatory glutamatergic synapses in the Central Nervous System (CNS). The critical early driver of LTP is autophosphorylation of the abundant postsynaptic enzyme, Ca2+/calmodulin-dependent protein kinase II (CaMKII). Autophosphorylation is initiated by Ca2+ flowing through NMDA receptors activated by strong synaptic activity. Its lifetime is ultimately determined by the balance of the rates of autophosphorylation and of dephosphorylation by protein phosphatase 1 (PP1). Here we have modeled the autophosphorylation and dephosphorylation of CaMKII during synaptic activity in a spine synapse using MCell4, an open source computer program for creating particle-based stochastic, and spatially realistic models of cellular microchemistry. The model integrates four earlier detailed models of separate aspects of regulation of spine Ca2+ and CaMKII activity, each of which incorporate experimentally measured biochemical parameters and have been validated against experimental data. We validate the composite model by showing that it accurately predicts previous experimental measurements of effects of NMDA receptor activation, including high sensitivity of induction of LTP to phosphatase activity in vivo, and persistence of autophosphorylation for a period of minutes after the end of synaptic stimulation. We then use the model to probe aspects of the mechanism of regulation of autophosphorylation of CaMKII that are difficult to measure in vivo. We examine the effects of "CaM-trapping," a process in which the affinity for Ca2+/CaM increases several hundred-fold after autophosphorylation. We find that CaM-trapping does not increase the proportion of autophosphorylated subunits in holoenzymes after a complex stimulus, as previously hypothesized. Instead, CaM-trapping may dramatically prolong the lifetime of autophosphorylated CaMKII through steric hindrance of dephosphorylation by protein phosphatase 1. The results provide motivation for experimental measurement of the extent of suppression of dephosphorylation of CaMKII by bound Ca2+/CaM. The composite MCell4 model of biochemical effects of complex stimuli in synaptic spines is a powerful new tool for realistic, detailed dissection of mechanisms of synaptic plasticity.

Role of Neural Circuits in Cognitive Impairment

Cognitive impairment refers to abnormalities in learning, memory and cognitive judgment, mainly manifested as symptoms such as decreased memory, impaired orientation and reduced computational ability. As the fundamental unit of information processing in the brain, neural circuits have recently attracted great attention due to their functions in regulating pain, emotion and behavior. Furthermore, a growing number of studies have suggested that neural circuits play an important role in cognitive impairment. Neural circuits can affect perception, attention and decision-making, they can also regulate language skill, thinking and memory. Pathological conditions crucially affecting the integrity and preservation of neural circuits and their connectivity will heavily impact cognitive abilities. Nowadays, technological developments have led to many novel methods for studying neural circuits, such as brain imaging, optogenetic techniques, and chemical genetics approaches. Therefore, neural circuits show great promise as a potential target in mitigating cognitive impairment. In this review we discuss the pathogenesis of cognitive impairment and the regulation and detection of neural circuits, thus highlighting the role of neural circuits in cognitive impairment. Hence, therapeutic agents against cognitive impairment may be developed that target neural circuits important in cognition.

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

Netrin-G2 is a membrane-anchored protein 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.(Trp202X) 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 the 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 receive 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.

Neuroplasticity in Parkinson's disease

Parkinson's disease (PD) is the second most frequent neurodegenerative disorder, affecting millions of people and rapidly increasing over the last decades. Even though there is no intervention yet to stop the neurodegenerative pathology, many efficient treatment methods are available, including for patients with advanced PD. Neuroplasticity is a fundamental property of the human brain to adapt both to external changes and internal insults and pathological processes. In this paper we examine the current knowledge and concepts concerning changes at network level, cellular level and molecular level as parts of the neuroplastic response to protein aggregation pathology, synapse loss and neuronal loss in PD. We analyse the beneficial, compensatory effects, such as augmentation of nigral neurons efficacy, as well as negative, maladaptive effects, such as levodopa-induced dyskinesia. Effects of physical activity and different treatments on neuroplasticity are considered and the opportunity of biomarkers identification and use is discussed.

Desipramine reverses remote memory deficits by activating calmodulin-CaMKII pathway in a UTX knockout mouse model of Kabuki syndrome

Background

Kabuki syndrome (KS) is a rare developmental disorder characterised by multiple congenital anomalies and intellectual disability. UTX (ubiquitously transcribed tetratricopeptide repeat, X chromosome), which encodes a histone demethylase, is one of the two major pathogenic risk genes for KS. Although intellectual disability is a key phenotype of KS, the role of UTX in cognitive function remains unclear. Currently, no targeted therapies are available for KS.

Aims

This study aimed to investigate how UTX regulates cognition, to explore the mechanisms underlying UTX dysfunction and to identify potential molecular targets for treatment.

Methods

We generated UTX conditional knockout mice and found that UTX deletion downregulated calmodulin transcription by disrupting H3K27me3 (trimethylated histone H3 at lysine 27) demethylation.

Results

UTX-knockout mice showed decreased phosphorylation of calcium / calmodulin-dependent protein kinase II, impaired long-term potentiation and deficit in remote contextual fear memory. These effects were reversed by an Food and Drug Administration-approved drug desipramine.

Conclusions

Our results reveal an epigenetic mechanism underlying the important role of UTX in synaptic plasticity and cognitive function, and suggest that desipramine could be a potential treatment for KS.

Neuroplasticity in the transition from acute to chronic pain

Acute pain is a transient sensation that typically serves as part of the body's defense mechanism. However, in certain patients, acute pain can evolve into chronic pain, which persists for months or even longer. Neuroplasticity refers to the capacity for variation and adaptive alterations in the morphology and functionality of neurons and synapses, and it plays a significant role in the transmission and modulation of pain. In this paper, we explore the molecular mechanisms and signaling pathways underlying neuroplasticity during the transition of pain. We also examine the effects of neurotransmitters, inflammatory mediators, and central sensitization on neuroplasticity, as well as the potential of neuroplasticity as a therapeutic strategy for preventing chronic pain. The aims of this article is to clarify the role of neuroplasticity in the transformation from acute pain to chronic pain, with the hope of providing a novel theoretical basis for unraveling the pathogenesis of chronic pain and offering more effective strategies and approaches for its diagnosis and treatment.

Adjunctive clozapine with bright light mitigates cognitive deficits by synaptic plasticity and neurogenesis in sub-chronic MK-801 treated mice

Schizophrenia impacts about 1 % of the global population, with clozapine (CLZ) being a critical treatment for refractory cases despite its limitations in effectiveness and adverse effects. Therefore, the search for more effective treatments remains urgent. Light treatment (LT) recognized for enhancing cognition and mood, presents a promising complementary approach. This study investigated the effects of CLZ and LT on cognitive impairments in a sub-chronic MK-801 induced schizophrenia mouse model. Results showed that both CLZ and CLZ + LT treatment elevate cognitive performance of sub-chronic MK-801 treated mice in serial behavioral tests over two months. Histological analysis revealed increased dendritic spine density and branching, and synaptic repair in the hippocampus with CLZ and CLZ + LT interventions. Furthermore, both treatments increased brain-derived neurotrophic factor (BDNF) expression in the hippocampus, likely contributing to cognitive amelioration in MK-801 treated mice. Additionally, BrdU labeling revealed that CLZ + LT further enhances neurogenesis in the dentate gyrus (DG) and lateral ventricle (LV) of sub-chronic MK-801 treated mice. These findings may have implications for the development of noninvasive and adjunctive treatment strategies aimed at alleviating cognitive impairments and improving functional outcomes in individuals with schizophrenia.

Sex-specific Concordance of Striatal Transcriptional Signatures of Opioid Addiction in Human and Rodent Brains

Opioid use disorder (OUD) has emerged as a severe, ongoing public health emergency. Current, frontline addiction treatment strategies fail to produce lasting abstinence in most users. This underscores the lasting effects of chronic opioid exposure and emphasizes the need to understand the molecular mechanisms of drug seeking and taking, but also how those alterations persist through acute and protracted withdrawal. Here, we used RNA sequencing in post-mortem human tissue from males (n=10) and females (n=10) with OUD and age and sex-matched comparison subjects. We compared molecular alterations in the nucleus accumbens (NAc) and dorsolateral prefrontal cortex (DLPFC) between humans with OUD and rodent models across distinct stages of opioid use and withdrawal (acute and prolonged) using differential gene expression and network-based approaches. We found that the molecular signature in the NAc of females with OUD mirrored effects seen in the NAc of female mice at all stages of exposure. Conversely, males with OUD showed strong overlap in expression profile with rats in acute withdrawal. Co-expression networks involved in post-transcriptional modification of RNA and epigenetic modification of chromatin state. This study provides fundamental insight into the converging molecular pathways altered by opioids across species. Further, this work helps to disentangle which alterations observed in humans with OUD are driven by acute drug exposure and which alterations are consequences of chronic exposure.

Signal flow in the NMDA receptor-dependent phosphoproteome regulates postsynaptic plasticity for aversive learning

Structural plasticity of dendritic spines in the nucleus accumbens (NAc) is crucial for learning from aversive experiences. Activation of NMDA receptors (NMDARs) stimulates Ca2+-dependent signaling that leads to changes in the actin cytoskeleton, mediated by the Rho family of GTPases, resulting in postsynaptic remodeling essential for learning. We investigated how phosphorylation events downstream of NMDAR activation drive the changes in synaptic morphology that underlie aversive learning. Large-scale phosphoproteomic analyses of protein kinase targets in mouse striatal/accumbal slices revealed that NMDAR activation resulted in the phosphorylation of 194 proteins, including RhoA regulators such as ARHGEF2 and ARHGAP21. Phosphorylation of ARHGEF2 by the Ca2+-dependent protein kinase CaMKII enhanced its RhoGEF activity, thereby activating RhoA and its downstream effector Rho-associated kinase (ROCK/Rho-kinase). Further phosphoproteomic analysis identified 221 ROCK targets, including the postsynaptic scaffolding protein SHANK3, which is crucial for its interaction with NMDARs and other postsynaptic scaffolding proteins. ROCK-mediated phosphorylation of SHANK3 in the NAc was essential for spine growth and aversive learning. These findings demonstrate that NMDAR activation initiates a phosphorylation cascade crucial for learning and memory.

Effects of β-asarone on spatial learning and memory impairment by exhaustive exercise-induced fatigue: Role of NR-CaMKII-ERK/CREB signal in hippocampus of rats

OBJECTIVE

It is to investigate the effects of β-asarone on learning and memory, hippocampal morphology, synaptophysin (SYP) and postsynaptic density 95(PSD95) protein expression, N-methyl-D-aspartic acid receptor 2B (NR2B)- Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) - Extracellular signal-regulated kinase (ERK) / Cyclic-AMP response element binding protein (CREB) signal in hippocampus of rats with exhaustive exercise-induced fatigue.

METHODS

Fifty Sprague-Dawley male rats were randomly divided into five groups: normal group, exercise group, exercise and β-asarone (2.5, 10, 40 mg/kg)-treated groups. The learning and memory in rats were tested by Morris water maze experiment. We measured the hippocampal morphology by Nissl staining. The levels of SYP, PSD95, NR2B, CaMKII, ERK1/2, CREB, p-NR2B, p-CaMKII, p-ERK1/2 and p-CREB expression were measured by western blot analysis.

RESULTS

The results demonstrated that β-asarone (10, 40 mg/kg) treatment significantly decreased the latency to find the platform, increased the time spent in the target quadrant and the number of crossing the platform of rats with exhaustive exercise-induced fatigue. β-asarone (10, 40 mg/kg) treatment increased the cell density in the hippocampus CA1 region, significantly up-regulated NR2B-CaMKII-ERK/CREB signal and improved the protein expression levels of SYP and PSD95 in hippocampus of rats with exhaustive exercise-induced fatigue.

CONCLUSIONS

It suggests that β-asarone could improve learning and memory of rats with exhaustive exercise-induced fatigue. The mechanism might be related to β-asarone protecting the morphology of hippocampus, increasing the protein expression levels of SYP and PSD95 and up-regulating NR2B-CaMKII-ERK/CREB signal in hippocampus of rats with exhaustive exercise-induced fatigue.

CaMK II in Cardiovascular Diseases, Especially CaMK II-δ: Friends or Enemies

Cardiovascular diseases (CVDs) tend to affect the young population and are associated with a significant economic burden and psychological distress to the society and families. The physiological and pathological processes underlying CVDs are complex. Ca2+/calmodulin-dependent kinase II (CaMK II), a protein kinase, has multiple biological functions. It participates in multiple pathological processes and plays a central role in the development of CVDs. Based on this, this paper analyzes the structural characteristics and distribution of CaMK II, the mechanism of action of CaMK II, and the relationship between CaMK II and CVDs, including ion channels, ischemia-reperfusion injury, arrhythmias, myocardial hypertrophy, cardiotoxicity, hypertension, and dilated cardiomyopathy. Given the different regulatory mechanisms of different isoforms of CaMK II, the clinical use of specific targeted inhibitors or novel compounds should be evaluated in future research to provide new directions.

Interplay of hippocampal long-term potentiation and long-term depression in enabling memory representations

Hippocampal long-term potentiation (LTP) and long-term depression (LTD) are Hebbian forms of synaptic plasticity that are widely believed to comprise the physiological correlates of associative learning. They comprise a persistent, input-specific increase or decrease, respectively, in synaptic efficacy that, in rodents, can be followed for days and weeks in vivo. Persistent (>24 h) LTP and LTD exhibit distinct frequency-dependencies and molecular profiles in the hippocampal subfields. Moreover, causal and genetic studies in behaving rodents indicate that both LTP and LTD fulfil specific and complementary roles in the acquisition and retention of spatial memory. LTP is likely to be responsible for the generation of a record of spatial experience, which may serve as an associative schema that can be re-used to expedite or facilitate subsequent learning. In contrast, LTD may enable modification and dynamic updating of this representation, such that detailed spatial content information is included and the schema is rendered unique and distinguishable from other similar representations. Together, LTP and LTD engage in a dynamic interplay that supports the generation of complex associative memories that are resistant to generalization. This article is part of a discussion meeting issue 'Long-term potentiation: 50 years on'.

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.

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.

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.

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.

Hub stability in the calcium calmodulin-dependent protein kinase II

The calcium calmodulin protein kinase II (CaMKII) is a multi-subunit ring assembly with a central hub formed by the association domains. There is evidence for hub polymorphism between and within CaMKII isoforms, but the link between polymorphism and subunit exchange has not been resolved. Here, we present near-atomic resolution cryogenic electron microscopy (cryo-EM) structures revealing that hubs from the α and β isoforms, either standalone or within an β holoenzyme, coexist as 12 and 14 subunit assemblies. Single-molecule fluorescence microscopy of Venus-tagged holoenzymes detects intermediate assemblies and progressive dimer loss due to intrinsic holoenzyme lability, and holoenzyme disassembly into dimers upon mutagenesis of a conserved inter-domain contact. Molecular dynamics (MD) simulations show the flexibility of 4-subunit precursors, extracted in-silico from the β hub polymorphs, encompassing the curvature of both polymorphs. The MD explains how an open hub structure also obtained from the β holoenzyme sample could be created by dimer loss and analysis of its cryo-EM dataset reveals how the gap could open further. An assembly model, considering dimer concentration dependence and strain differences between polymorphs, proposes a mechanism for intrinsic hub lability to fine-tune the stoichiometry of αβ heterooligomers for their dynamic localization within synapses in neurons.

Neural circuits regulating visceral pain

Visceral hypersensitivity, a common clinical manifestation of irritable bowel syndrome, may contribute to the development of chronic visceral pain, which is a major challenge for both patients and health providers. Neural circuits in the brain encode, store, and transfer pain information across brain regions. In this review, we focus on the anterior cingulate cortex and paraventricular nucleus of the hypothalamus to highlight the progress in identifying the neural circuits involved in visceral pain. We also discuss several neural circuit mechanisms and emphasize the importance of cross-species, multiangle approaches and the identification of specific neurons in determining the neural circuits that control visceral pain.

Essential role of ROS - 8-Nitro-cGMP signaling in long-term memory of motor learning and cerebellar synaptic plasticity

Although reactive oxygen species (ROS) are known to have harmful effects in organisms, recent studies have demonstrated expression of ROS synthases at various parts of the organisms and the controlled ROS generation, suggesting possible involvement of ROS signaling in physiological events of individuals. However, physiological roles of ROS in the CNS, including functional roles in higher brain functions or neuronal activity-dependent ROS production, remain to be elucidated. Here, we demonstrated involvement of ROS - 8-NO2-cGMP signaling in motor learning and synaptic plasticity in the cerebellum. In the presence of inhibitors of ROS signal or ROS synthases, cerebellar motor learning was impaired, and the stimulus inducing long-term depression (LTD), cellular basis for the motor learning, failed to induce LTD but induced long-term potentiation (LTP)-like change at cerebellar synapses. Furthermore, ROS was produced by LTD-inducing stimulus in enzyme-dependent manner, and excess administration of the antioxidant vitamin E impaired cerebellar motor learning, suggesting beneficial roles of endogenous ROS in the learning. As a downstream signal, involvement of 8-NO2-cGMP in motor learning and cerebellar LTD were also revealed. These findings indicate that ROS - 8-NO2-cGMP signal is activated by neuronal activity and is essential for cerebellum-dependent motor learning and synaptic plasticity, demonstrating involvement of the signal in physiological function of brain systems.

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 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 runaway 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.

A biochemical description of postsynaptic plasticity-with timescales ranging from milliseconds to seconds

Synaptic plasticity [long-term potentiation/depression (LTP/D)], is a cellular mechanism underlying learning. Two distinct types of early LTP/D (E-LTP/D), acting on very different time scales, have been observed experimentally-spike timing dependent plasticity (STDP), on time scales of tens of ms; and behavioral time scale synaptic plasticity (BTSP), on time scales of seconds. BTSP is a candidate for a mechanism underlying rapid learning of spatial location by place cells. Here, a computational model of the induction of E-LTP/D at a spine head of a synapse of a hippocampal pyramidal neuron is developed. The single-compartment model represents two interacting biochemical pathways for the activation (phosphorylation) of the kinase (CaMKII) with a phosphatase, with ion inflow through channels (NMDAR, CaV1,Na). The biochemical reactions are represented by a deterministic system of differential equations, with a detailed description of the activation of CaMKII that includes the opening of the compact state of CaMKII. This single model captures realistic responses (temporal profiles with the differing timescales) of STDP and BTSP and their asymmetries. The simulations distinguish several mechanisms underlying STDP vs. BTSP, including i) the flow of [Formula: see text] through NMDAR vs. CaV1 channels, and ii) the origin of several time scales in the activation of CaMKII. The model also realizes a priming mechanism for E-LTP that is induced by [Formula: see text] flow through CaV1.3 channels. Once in the spine head, this small additional [Formula: see text] opens the compact state of CaMKII, placing CaMKII ready for subsequent induction of LTP.

The role and mechanism of esketamine in preventing and treating remifentanil-induced hyperalgesia based on the NMDA receptor-CaMKII pathway

Remifentanil-induced hyperalgesia (RIH) is a common clinical phenomenon that limits the use of opioids in pain management. Esketamine, a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, has been shown to prevent and treat RIH. However, the underlying effect mechanism of esketamine on RIH remains unclear. This study aimed to investigate the role and mechanism of esketamine in preventing and treating RIH based on the NMDA receptor-CaMKIIα pathway. In this study, an experimental animal model was used to determine the therapeutic effect of esketamine on pain elimination. Moreover, the mRNA transcription and protein expression levels of CaMKII and GluN2B were investigated to offer evidence of the protective capability of esketamine in ameliorating RIH. The results demonstrated that esketamine attenuated RIH by inhibiting CaMKII phosphorylation and downstream signaling pathways mediated by the NMDA receptor. Furthermore, ketamine reversed the upregulation of spinal CaMKII induced by remifentanil. These findings suggest that the NMDA receptor-CaMKII pathway plays a critical role in the development of RIH, and ketamine's effect on this pathway may provide a new therapeutic approach for the prevention and treatment of RIH.

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).

Co-activation of NMDAR and mGluRs controls protein nanoparticle-induced osmotic pressure in neurotoxic edema

BACKGROUND

Glutamate stimuli and hyperactivation of its receptor are predominant determinants of ischemia-induced cytotoxic cerebral edema, which is closely associated with protein nanoparticle (PN)-induced increases in osmotic pressure. Herein, we investigated the electrochemical and mechanical mechanisms underlying the neuron swelling induced by PNs via the co-activation of N-methyl-D-aspartate receptor subunit (NMDAR) and excitatory metabotropic glutamate receptors (mGluRs).

RESULTS

We observed that co-activation of ionic glutamate receptor NMDAR and Group I metabotropic mGluRs promoted alteration of PN-induced membrane potential and increased intracellular osmosis, which was closely associated with calcium and voltage-dependent ion channels. In addition, activation of NMDAR-induced calmodulin (CaM) and mGluR downstream diacylglycerol (DAG)/protein kinase C α (PKCα) were observed to play crucial roles in cytotoxic hyperosmosis. The crosstalk between CaM and PKCα could upregulate the sensitivity and sustained opening of sulfonylurea receptor 1 (SUR1)-transient receptor potential cation channel subfamily M member 4 (TRPM4) and transmembrane protein 16 A (TMEM16A) channels, respectively, maintaining the massive Na+/Cl- influx, and the resultant neuron hyperosmosis and swelling. Intracellular PNs and Na+/Cl- influx were found to be as potential targets for cerebral edema treatment, using the neurocyte osmosis system and a cerebral ischemic rat model.

CONCLUSIONS

This study highlights PNs as a key factor in "electrochemistry-tension" signal transduction controlling Na+/Cl- ion channels and increased osmotic pressure in ischemia-induced cytotoxic edema. Moreover, enhanced sensitivity in both Na+ and Cl- ion channels also has a crucial role in cerebral edema.

Excitation-transcription coupling, neuronal gene expression and synaptic plasticity

Excitation-transcription coupling (E-TC) links synaptic and cellular activity to nuclear gene transcription. It is generally accepted that E-TC makes a crucial contribution to learning and memory through its role in underpinning long-lasting synaptic enhancement in late-phase long-term potentiation and has more recently been linked to late-phase long-term depression: both processes require de novo gene transcription, mRNA translation and protein synthesis. E-TC begins with the activation of glutamate-gated N-methyl-D-aspartate-type receptors and voltage-gated L-type Ca2+ channels at the membrane and culminates in the activation of transcription factors in the nucleus. These receptors and ion channels mediate E-TC through mechanisms that include long-range signalling from the synapse to the nucleus and local interactions within dendritic spines, among other possibilities. Growing experimental evidence links these E-TC mechanisms to late-phase long-term potentiation and learning and memory. These advances in our understanding of the molecular mechanisms of E-TC mean that future efforts can focus on understanding its mesoscale functions and how it regulates neuronal network activity and behaviour in physiological and pathological conditions.

In Vitro Models of Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis (ALS) is one of the commonest neurodegenerative diseases of adult-onset, which is characterized by the progressive death of motor neurons in the cerebral cortex, brain stem and spinal cord. The dysfunction and death of motor neurons lead to the progressive muscle weakness, atrophy, fasciculations, spasticity and ultimately the whole paralysis of body. Despite the identification of several genetic mutations associated with the pathogenesis of ALS, including mutations in chromosome 9 open reading frame 72 leading to the abnormal expansion of GGGGCC repeat sequence, TAR DNA-binding protein 43, fused in sarcoma/translocated in liposarcoma, copper/zinc superoxide dismutase 1 (SOD1) and TANK-binding kinase 1, the exact mechanisms underlying the specific degeneration of motor neurons that causes ALS remain incompletely understood. At present, since the transgenic model expressed SOD1 mutants was established, multiple in vitro models of ALS have been developed for studying the pathology, pathophysiology and pathogenesis of ALS as well as searching the effective neurotherapeutics. This review reviewed the details of present established in vitro models used in studying the pathology, pathophysiology and pathogenesis of ALS. Meanwhile, we also discussed the advantages, disadvantages, cost and availability of each models.

CaMKII autophosphorylation but not downstream kinase activity is required for synaptic memory

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 kinase activity. Thus, autophosphorylation, together with binding to the GluN2B subunit, are the only two requirements for CaMKII in synaptic memory.