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On page 4 showing 61 ~ 80 papers out of 150 papers

Postnatal age-differential ASD-like transcriptomic, synaptic, and behavioral deficits in Myt1l-mutant mice.

  • Seongbin Kim‎ et al.
  • Cell reports‎
  • 2022‎

Myelin transcription factor 1 like (Myt1l), a zinc-finger transcription factor, promotes neuronal differentiation and is implicated in autism spectrum disorder (ASD) and intellectual disability. However, it remains unclear whether Myt1l promotes neuronal differentiation in vivo and its deficiency in mice leads to disease-related phenotypes. Here, we report that Myt1l-heterozygous mutant (Myt1l-HT) mice display postnatal age-differential ASD-related phenotypes: newborn Myt1l-HT mice, with strong Myt1l expression, show ASD-like transcriptomic changes involving decreased synaptic gene expression and prefrontal excitatory synaptic transmission and altered righting reflex. Juvenile Myt1l-HT mice, with markedly decreased Myt1l expression, display reverse ASD-like transcriptomes, increased prefrontal excitatory transmission, and largely normal behaviors. Adult Myt1l-HT mice show ASD-like transcriptomes involving astrocytic and microglial gene upregulation, increased prefrontal inhibitory transmission, and behavioral deficits. Therefore, Myt1l haploinsufficiency leads to ASD-related phenotypes in newborn mice, which are temporarily normalized in juveniles but re-appear in adults, pointing to continuing phenotypic changes long after a marked decrease of Myt1l expression in juveniles.


Dysbiotic but nonpathogenic shift in the fecal mycobiota of patients with rheumatoid arthritis.

  • Eun Ha Lee‎ et al.
  • Gut microbes‎
  • 2022‎

Rheumatoid arthritis (RA) is closely associated with the oral and gut microbiomes. Fungal cell wall components initiate inflammatory arthritis in mouse models. However, little is known regarding the role of the fungal community in the pathogenesis of RA. To evaluate the association between RA and the gut microbiome, investigations of bacterial and fungal communities in patients with RA are necessary. Therefore, we investigated the compositions and associations of fecal bacterial and fungal communities in 30 healthy controls and 99 patients with RA. The relative abundances of Bifidobacterium and Blautia decreased, whereas the relative abundance of Streptococcus increased, in patients with RA. The relative abundance of Candida in the fecal fungal community was higher in patients with RA than in healthy controls, while the relative abundance of Aspergillus was higher in healthy controls than in patients with RA. Candida species-specific gene amplification showed that C. albicans was the most abundant species of Candida. Ordination analysis and random forest classification models supported the findings of structural changes in bacterial and fungal communities. Aspergillus was the core fecal fungal genus in healthy controls, although Saccharomyces spp. are typically predominant in Western cohorts. In addition, bacterial-fungal association analyses showed that the hub node had shifted from fungi to bacteria in patients with RA. The finding of fungal dysbiosis in patients with RA suggests that fungi play critical roles in the fecal microbial communities and pathogenesis of RA.


Tamalin Function Is Required for the Survival of Neurons and Oligodendrocytes in the CNS.

  • Yongbo Seo‎ et al.
  • International journal of molecular sciences‎
  • 2022‎

Tamalin is a post-synaptic scaffolding protein that interacts with group 1 metabotropic glutamate receptors (mGluRs) and several other proteins involved in protein trafficking and cytoskeletal events, including neuronal growth and actin reorganization. It plays an important role in synaptic plasticity in vitro by controlling the ligand-dependent trafficking of group 1 mGluRs. Abnormal regulation of mGluRs in the central nervous system (CNS) is associated with glutamate-mediated neurodegenerative disorders. However, the pathological consequences of tamalin deficiency in the CNS are unclear. In this study, tamalin knockout (KO) zebrafish and mice exhibited neurodegeneration along with oligodendrocyte degeneration in the post-embryonic CNS to adulthood without any developmental defects, thus suggesting the function of tamalin is more important in the postnatal stage to adulthood than that in CNS development. Interestingly, hypomyelination was independent of axonal defects in the CNS of tamalin knockout zebrafish and mice. In addition, the loss of Arf6, a downstream signal of tamalin scaffolding protein, synergistically induced neurodegeneration in tamalin KO zebrafish even in the developing CNS. Furthermore, tamalin KO zebrafish displayed increased mGluR5 expression. Taken together, tamalin played an important role in neuronal and oligodendrocyte survival and myelination through the regulation of mGluR5 in the CNS.


A20 Inhibits LPS-Induced Inflammation by Regulating TRAF6 Polyubiquitination in Rainbow Trout.

  • Ju Hye Jang‎ et al.
  • International journal of molecular sciences‎
  • 2021‎

The ubiquitin-editing enzyme A20 is known to inhibit the NF-κB transcription factor in the Toll-like receptor (TLR) pathways, thereby negatively regulating inflammation. However, its role in the TLR signaling pathway in fish is still largely unknown. Here, we identified a gene encoding A20 (OmA20) in rainbow trout, Oncorhynchus mykiss, and investigated its role in TLR response regulation. The deduced amino acid sequence of OmA20 contained a conserved N-terminal ovarian tumor (OTU) domain and seven C-terminal zinc-finger (ZnF) domains. Lipopolysaccharide (LPS) stimulation increased OmA20 expression in RTH-149 cells. In LPS-stimulated RTH-149 cells, gain- and loss-of-function experiments revealed that OmA20 inhibited MAPK and NF-κB activation, as well as the expression of pro-inflammatory cytokines. OmA20 interacted with TRAF6, a key molecule involved in the activation of TLR-mediated NF-κB signaling pathways. LPS treatment increased the K63-linked polyubiquitination of TRAF6 in RTH-149 cells, which was suppressed when OmA20 was forced expression. Furthermore, mutations in the OTU domain significantly decreased deubiquitination of the K63-linked ubiquitin chain on TRAF6, indicating that deubiquitinase activity is dependent on the OTU domain. These findings suggest that OmA20, like those of mammals, reduces LPS-induced inflammation in rainbow trout, most likely by regulating K63-linked ubiquitination of TRAF6.


Shank2 Deletion in Parvalbumin Neurons Leads to Moderate Hyperactivity, Enhanced Self-Grooming and Suppressed Seizure Susceptibility in Mice.

  • Seungjoon Lee‎ et al.
  • Frontiers in molecular neuroscience‎
  • 2018‎

Shank2 is an abundant postsynaptic scaffolding protein implicated in neurodevelopmental and psychiatric disorders, including autism spectrum disorders (ASD). Deletion of Shank2 in mice has been shown to induce social deficits, repetitive behaviors, and hyperactivity, but the identity of the cell types that contribute to these phenotypes has remained unclear. Here, we report a conditional mouse line with a Shank2 deletion restricted to parvalbumin (PV)-positive neurons (Pv-Cre;Shank2fl/fl mice). These mice display moderate hyperactivity in both novel and familiar environments and enhanced self-grooming in novel, but not familiar, environments. In contrast, they showed normal levels of social interaction, anxiety-like behavior, and learning and memory. Basal brain rhythms in Pv-Cre;Shank2fl/fl mice, measured by electroencephalography, were normal, but susceptibility to pentylenetetrazole (PTZ)-induced seizures was decreased. These results suggest that Shank2 deletion in PV-positive neurons leads to hyperactivity, enhanced self-grooming and suppressed brain excitation.


The potato rhizosphere microbiota correlated to the yield of three different regions in Korea.

  • Gye-Ryeong Bak‎ et al.
  • Scientific reports‎
  • 2024‎

We examined potato rhizosphere bacterial and fungal communities across three regions: Cheongju, Pyeongchang, and Gangneung. These regions have varying soil and climate conditions, resulting in different yields. We found that precipitation was the main limiting factor in our study while soil physiochemical factors affect bacterial and fungal microbiota in correlation with yield. Both bacterial and fungal microbiota showed distinct patterns according to the regions. ASVs positively correlated with yield were predominantly found in the Pyeongchang region which also produced the highest yields, while ASVs negatively correlated with yield were associated with Gangneung where the lowest yields were observed. The greatest bacterial and fungal diversity was detected in Pyeongchang consisting of Propionibacteriales, Burkholderiales, and Vicinamibacteriales. Gangneung, on the other hand primarily belong to Sordariales, Mortierellales, Cystofilobasidiales, and Tremellales. The putative yield-negative ASVs detected in Gangneung may have been influenced by drought stress. This work has highlighted key bacterial and fungal taxa as well as core taxa that may potentially be associated with high and low yields of potato in relation to metadata which includes soil chemical and physical parameters as well as weather data. Taken together we suggest that this information can be used to assess site suitability for potato production.


Cloning and localization of rgpr85 encoding rat G-protein-coupled receptor.

  • Jongrye Jeon‎ et al.
  • Biochemical and biophysical research communications‎
  • 2002‎

In an attempt to isolate genes involved in the brain development using ordered differential display PCR, we cloned rgpr85 which encodes rat G-protein-coupled receptor with high degree of identity to the amine-like neurotransmitter receptors. This gene was found to be localized at rat chromosome 4q21. In situ hybridization demonstrated that rgpr85 was predominantly expressed in the developing brain and spinal cord. Hybridization signal was especially abundant within the embryonic cortical plates where postmitotic cortical neurons are localized. In the cerebral cortex, the expression of rgpr85 was gradually decreased postnatally and became undetectable by P18. However, weak but significant expression of rgpr85 was maintained in the adult hippocampal formation, olfactory bulb, and cerebellum. Interestingly, rgpr85 expression was transiently induced in the adult hippocampal formation, piriform cortex, and amygdaloid complex by kainic acid (KA) treatment. Thus, dynamic regulation of rgpr85 expression suggests an importance of rgpr85-mediated signaling in the development of cerebral cortex and in the KA-induced responses in the adult brain.


GABA Neuronal Deletion of Shank3 Exons 14-16 in Mice Suppresses Striatal Excitatory Synaptic Input and Induces Social and Locomotor Abnormalities.

  • Taesun Yoo‎ et al.
  • Frontiers in cellular neuroscience‎
  • 2018‎

Shank3 is an excitatory postsynaptic scaffolding protein implicated in multiple brain disorders, including autism spectrum disorders (ASD) and Phelan-McDermid syndrome (PMS). Although previous neurobiological studies on Shank3 and Shank3-mutant mice have revealed diverse roles of Shank3 in the regulation of synaptic, neuronal and brain functions, whether Shank3 expression in specific cell types distinctly contributes to mouse phenotypes remains largely unclear. In the present study, we generated two Shank3-mutant mouse lines (exons 14-16) carrying global and GABA neuron-specific deletions and characterized their electrophysiological and behavioral phenotypes. These mouse lines show similar decreases in excitatory synaptic input onto dorsolateral striatal neurons. In addition, the abnormal social and locomotor behaviors observed in global Shank3-mutant mice are strongly mimicked by GABA neuron-specific Shank3-mutant mice, whereas the repetitive and anxiety-like behaviors are only partially mimicked. These results suggest that GABAergic Shank3 (exons 14-16) deletion has strong influences on striatal excitatory synaptic transmission and social and locomotor behaviors in mice.


Usefulness of serum lactate as a predictor of successful discontinuation of continuous atropine infusion in patients with severe acute organophosphate poisoning.

  • Ho Chul Kwon‎ et al.
  • Clinical and experimental emergency medicine‎
  • 2018‎

In severe organophosphate (OP) poisoning, administration of atropine via continuous intravenous infusion is typically considered. To date, there have been no studies on predicting successful atropine discontinuation through plasma cholinesterase (PChE) and serum lactate levels, which are monitored during critical care in severe acute OP poisoning. Therefore, we retrospectively evaluated the usefulness of serum lactate and PChE as predictors of successful discontinuation of atropine infusion.


Diagnostic status and age at diagnosis of hypertension on adherence to lifestyle recommendations.

  • Hyun Kim‎ et al.
  • Preventive medicine reports‎
  • 2019‎

Regular physical activity, smoking cessation, and moderate alcohol consumption are important lifestyle behaviors that can be modified when managing hypertension. This study examined the associations of diagnostic status and age at hypertension diagnosis with lifestyle behaviors among individuals with hypertension. Data came from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2012 (N = 5231). Multinomial logistic regression models were used to estimate the relative risk (RR) of adopting lifestyle behaviors. A diagnosis of hypertension was associated with an individual being a past smoker (RR = 1.26, 95% CI: 1.05, 1.52). There was an association between duration since diagnosis and being a past smoker (RR = 1.01; 95% CI 1.01, 1.02; P = 0.004). Excessive drinking was inversely associated with duration since diagnosis (RR = 0.95; 95% CI 0.94, 0.96; P < 0.001). Older age at diagnosis was associated with the risk of being a past smoker (RR = 1.03; 95% CI 1.02, 1.04; P-value<0.001) and negatively associated with excessive drinking (RR = 0.96; 95% CI 0.95, 0.97; P < 0.001). Individuals who exercised, even though less than the recommended time, were more likely to have younger age at diagnosis (RR = 0.98; 95% CI 0.97, 0.99; P < 0.001) and shorter duration since diagnosis (RR = 0.98; 95% CI 0.96, 0.99; P < 0.001) compared to individuals with who did not engage in physical activity. Individuals with diagnosed hypertension were more likely to quit smoking, and those with younger age at diagnosis or shorter duration tended to exercise regularly. Regular visits to doctors should focus on hypertension control and health behavior modifications.


Regulation of TIM-3 expression in a human T cell line by tumor-conditioned media and cyclic AMP-dependent signaling.

  • Su Jin Yun‎ et al.
  • Molecular immunology‎
  • 2019‎

T cell immunoglobulin and mucin domain-3 (TIM-3) expression increases in exhausted T cells, which inhibits T cell function. TIM-3 expression is supposedly up-regulated in tumor-bearing individuals via chronic antigenic stimulation of T cells. Considering the immunosuppressive nature of the tumor microenvironment, we investigated whether tumor-secreted molecules might enhance TIM-3 expression in Jurkat T cells. We observed that TIM-3 expression was increased by the activation of prostaglandin (PG) E2 and cyclic AMP (cAMP) signaling pathways. Adenylate cyclase activation led to protein kinase A (PKA)-dependent upregulation of the TIM-3 minimal promoter region and of upstream conserved non-coding sequences. TIM-3 expression in Jurkat T cells was increased by the exposure to breast tumor cell-conditioned media partially through the interaction between PGE2 and its receptor, EP4. Our results propose that tumor-secreted molecules such as PGE2, which activates PKA and EPAC, may regulate TIM-3 expression in T cells.


Long-Term Isolation Elicits Depression and Anxiety-Related Behaviors by Reducing Oxytocin-Induced GABAergic Transmission in Central Amygdala.

  • Rafael T Han‎ et al.
  • Frontiers in molecular neuroscience‎
  • 2018‎

Isolation stress is a major risk factor for neuropsychiatric disorders such as depressive and anxiety disorders. However, the molecular mechanisms underlying isolation-induced neuropsychiatric disorders remain elusive. In the present study, we investigated the subcellular mechanisms by which long-term isolation elicits depression and anxiety-related behaviors in mice. First, we found that long-term isolation induced depression-related behaviors in the forced swimming test (FST) and the sucrose preference test, as well as anxiety-related behaviors in the elevated zero maze test (EZMT) and the open field test. Next, we showed that intracentral amygdala (CeA) injection of oxytocin (OXT), but not intracerebroventricular injection, attenuated isolation-induced depression and anxiety-related behaviors via oxytocin receptor (OXTR), not vasopressin-1a receptor (V1aR), in the FST and EZMT, respectively. Quantitative real-time polymerase chain reaction analysis revealed that after 5 weeks of isolation, mRNA transcription of OXTR in the CeA, but not that of V1aR, significantly decreased, whereas OXT and vasopressin mRNA transcription in the paraventricular nucleus of hypothalamus did not change significantly. Whole-cell patch clamping of acute brain slices demonstrated that the frequency of miniature inhibitory postsynaptic currents (mIPSCs) in CeA neurons, but not their amplitude, was lower in isolated mice than in group-housed mice. Notably, OXT treatment increased the mIPSC frequency in the CeA neurons, but to a lesser extent in the case of isolated mice than in that of group-housed mice via OXTR. Taken together, our findings suggest that long-term isolation down-regulates OXTR mRNA transcription and diminishes OXT-induced inhibitory synaptic transmission in the CeA and may contribute to the development of depression and anxiety-related behaviors in isolated mice through the enhancement of CeA activity.


Vitamin C modulates lead excretion in rats.

  • Hoseob Lihm‎ et al.
  • Anatomy & cell biology‎
  • 2013‎

Lead, one of the most toxic heavy metals, takes longer time to be excreted from the body than other heavy metals. The purpose of this study is, by measuring lead excretion via urine and feces, to find out the effect of vitamin C in lead chelation. Thirty-six rats were randomly assorted into four groups. All 33 rats except for the control group were administered with lead, before orally administered with different doses of vitamin C per kilogram of body weight. The lead excretion levels in urine and feces as well as the survival rate were then measured for each group. The rats with lead administrations (10/13, 76.9%) with lead administrations only, 10/11 rats (90.9%) with lead administrations and low dose of vitamin C, 9/9 rats (100%) with lead administrations and high dose of vitamin C survived. Among the 29 surviving rats, low vitamin C intake group exhibited higher urinary excretion than the lead only group. The urinary excretion level in high dose vitamin C intakegroup was significantly higher than the lead only group. In addition, fecal lead excretion seemed to be increased in the high dose vitamin C intake group, compared to the group with lead administrations only with statistical significance. Through animal experiment, it was found out that administrating high dose of vitamin C accelerated the excretion of lead in body compared to low dose of vitamin C.


Genetic diversity and relationships of korean chicken breeds based on 30 microsatellite markers.

  • Sangwon Suh‎ et al.
  • Asian-Australasian journal of animal sciences‎
  • 2014‎

The effective management of endangered animal genetic resources is one of the most important concerns of modern breeding. Evaluation of genetic diversity and relationship of local breeds is an important factor towards the identification of unique and valuable genetic resources. This study aimed to analyze the genetic diversity and population structure of six Korean native chicken breeds (n = 300), which were compared with three imported breeds in Korea (n = 150). For the analysis of genetic diversity, 30 microsatellite markers from FAO/ISAG recommended diversity panel or previously reported microsatellite markers were used. The number of alleles ranged from 2 to 15 per locus, with a mean of 8.13. The average observed heterozygosity within native breeds varied between 0.46 and 0.59. The overall heterozygote deficiency (F IT) in native chicken was 0.234±0.025. Over 30.7% of F IT was contributed by within-population deficiency (F IS). Bayesian clustering analysis, using the STRUCTURE software suggested 9 clusters. This study may provide the background for future studies to identify the genetic uniqueness of the Korean native chicken breeds.


SALM4 suppresses excitatory synapse development by cis-inhibiting trans-synaptic SALM3-LAR adhesion.

  • Eunkyung Lie‎ et al.
  • Nature communications‎
  • 2016‎

Synaptic adhesion molecules regulate various aspects of synapse development, function and plasticity. These functions mainly involve trans-synaptic interactions and positive regulations, whereas cis-interactions and negative regulation are less understood. Here we report that SALM4, a member of the SALM/Lrfn family of synaptic adhesion molecules, suppresses excitatory synapse development through cis inhibition of SALM3, another SALM family protein with synaptogenic activity. Salm4-mutant (Salm4(-/-)) mice show increased excitatory synapse numbers in the hippocampus. SALM4 cis-interacts with SALM3, inhibits trans-synaptic SALM3 interaction with presynaptic LAR family receptor tyrosine phosphatases and suppresses SALM3-dependent presynaptic differentiation. Importantly, deletion of Salm3 in Salm4(-/-) mice (Salm3(-/-); Salm4(-/-)) normalizes the increased excitatory synapse number. These results suggest that SALM4 negatively regulates excitatory synapses via cis inhibition of the trans-synaptic SALM3-LAR adhesion.


Bipolar Disorder Associated microRNA, miR-1908-5p, Regulates the Expression of Genes Functioning in Neuronal Glutamatergic Synapses.

  • Yoonhee Kim‎ et al.
  • Experimental neurobiology‎
  • 2016‎

Bipolar disorder (BD), characterized by recurrent mood swings between depression and mania, is a highly heritable and devastating mental illness with poorly defined pathophysiology. Recent genome-wide molecular genetic studies have identified several protein-coding genes and microRNAs (miRNAs) significantly associated with BD. Notably, some of the proteins expressed from BD-associated genes function in neuronal synapses, suggesting that abnormalities in synaptic function could be one of the key pathogenic mechanisms of BD. In contrast, however, the role of BD-associated miRNAs in disease pathogenesis remains largely unknown, mainly because of a lack of understanding about their target mRNAs and pathways in neurons. To address this problem, in this study, we focused on a recently identified BD-associated but uncharacterized miRNA, miR-1908-5p. We identified and validated its novel target genes including DLGAP4, GRIN1, STX1A, CLSTN1 and GRM4, which all function in neuronal glutamatergic synapses. Moreover, bioinformatic analyses of human brain expression profiles revealed that the expression levels of miR-1908-5p and its synaptic target genes show an inverse-correlation in many brain regions. In our preliminary experiments, the expression of miR-1908-5p was increased after chronic treatment with valproate but not lithium in control human neural progenitor cells. In contrast, it was decreased by valproate in neural progenitor cells derived from dermal fibroblasts of a BD subject. Together, our results provide new insights into the potential role of miR-1908-5p in the pathogenesis of BD and also propose a hypothesis that neuronal synapses could be a key converging pathway of some BD-associated protein-coding genes and miRNAs.


The role of inositol 1,4,5-trisphosphate 3-kinase A in regulating emotional behavior and amygdala function.

  • Sooyoung Chung‎ et al.
  • Scientific reports‎
  • 2016‎

Inositol 1,4,5-trisphosphate 3-kinase A (IP3K-A) is a molecule enriched in the brain and neurons that regulates intracellular calcium levels via signaling through the inositol trisphosphate receptor. In the present study, we found that IP3K-A expression is highly enriched in the central nucleus of the amygdala (CeA), which plays a pivotal role in the processing and expression of emotional phenotypes in mammals. Genetic abrogation of IP3K-A altered amygdala gene expression, particularly in genes involved in key intracellular signaling pathways and genes mediating fear- and anxiety-related behaviors. In agreement with the changes in amygdala gene expression profiles, IP3K-A knockout (KO) mice displayed more robust responses to aversive stimuli and spent less time in the open arms of the elevated plus maze, indicating high levels of innate fear and anxiety. In addition to behavioral phenotypes, decreased excitatory and inhibitory postsynaptic current and reduced c-Fos immunoreactivity in the CeA of IP3K-A KO mice suggest that IP3K-A has a profound influence on the basal activities of fear- and anxiety-mediating amygdala circuitry. In conclusion, our findings collectively demonstrate that IP3K-A plays an important role in regulating affective states by modulating metabotropic receptor signaling pathways and neural activity in the amygdala.


Postmortem mRNA expression patterns in left ventricular myocardial tissues and their implications for forensic diagnosis of sudden cardiac death.

  • Gi Hoon Son‎ et al.
  • Molecules and cells‎
  • 2014‎

Sudden cardiac death (SCD), which is primarily caused by lethal heart disorders resulting in structural and arrhythmogenic abnormalities, is one of the prevalent modes of death in most developed countries. Myocardial ischemia, mainly due to coronary artery disease, is the most common type of heart disease leading to SCD. However, postmortem diagnosis of SCD is frequently complicated by obscure histological evidence. Here, we show that certain mRNA species, namely those encoding hemoglobin A1/2 and B (Hba1/2 and Hbb, respectively) as well as pyruvate dehydrogenase kinase 4 (Pdk4), exhibit distinct postmortem expression patterns in the left ventricular free wall of SCD subjects when compared with their expression patterns in the corresponding tissues from control subjects with non-cardiac causes of death. Hba1/2 and Hbb mRNA expression levels were higher in ischemic SCD cases with acute myocardial infarction or ischemic heart disease without recent infarction, and even in cardiac death subjects without apparent pathological signs of heart injuries, than control subjects. By contrast, Pdk4 mRNA was expressed at lower levels in SCD subjects. In conclusion, we found that altered myocardial Hba1/2, Hbb, and Pdk4 mRNA expression patterns can be employed as molecular signatures of fatal cardiac dysfunction to forensically implicate SCD as the primary cause of death.


ABA renewal involves enhancements in both GluA2-lacking AMPA receptor activity and GluA1 phosphorylation in the lateral amygdala.

  • Kyungjoon Park‎ et al.
  • PloS one‎
  • 2014‎

Fear renewal, the context-specific relapse of fear following fear extinction, is a leading animal model of post-traumatic stress disorders (PTSD) and fear-related disorders. Although fear extinction can diminish fear responses, this effect is restricted to the context where the extinction is carried out, and the extinguished fear strongly relapses when assessed in the original acquisition context (ABA renewal) or in a context distinct from the conditioning and extinction contexts (ABC renewal). We have previously identified Ser831 phosphorylation of GluA1 subunit in the lateral amygdala (LA) as a key molecular mechanism for ABC renewal. However, molecular mechanisms underlying ABA renewal remain to be elucidated. Here, we found that both the excitatory synaptic efficacy and GluA2-lacking AMPAR activity at thalamic input synapses onto the LA (T-LA synapses) were enhanced upon ABA renewal. GluA2-lacking AMPAR activity was also increased during low-threshold potentiation, a potential cellular substrate of renewal, at T-LA synapses. The microinjection of 1-naphtylacetyl-spermine (NASPM), a selective blocker of GluA2-lacking AMPARs, into the LA attenuated ABA renewal, suggesting a critical role of GluA2-lacking AMPARs in ABA renewal. We also found that Ser831 phosphorylation of GluA1 in the LA was increased upon ABA renewal. We developed a short peptide mimicking the Ser831-containing C-tail region of GluA1, which can be phosphorylated upon renewal (GluA1S); thus, the phosphorylated GluA1S may compete with Ser831-phosphorylated GluA1. This GluA1S peptide blocked the low-threshold potentiation when dialyzed into a recorded neuron. The microinjection of a cell-permeable form of GluA1S peptide into the LA attenuated ABA renewal. In support of the GluA1S experiments, a GluA1D peptide (in which the serine at 831 is replaced with a phosphomimetic amino acid, aspartate) attenuated ABA renewal when microinjected into the LA. These findings suggest that enhancements in both the GluA2-lacking AMPAR activity and GluA1 phosphorylation at Ser831 are required for ABA renewal.


Regulated RalBP1 binding to RalA and PSD-95 controls AMPA receptor endocytosis and LTD.

  • Kihoon Han‎ et al.
  • PLoS biology‎
  • 2009‎

Long-term depression (LTD) is a long-lasting activity-dependent decrease in synaptic strength. NMDA receptor (NMDAR)-dependent LTD, an extensively studied form of LTD, involves the endocytosis of AMPA receptors (AMPARs) via protein dephosphorylation, but the underlying mechanism has remained unclear. We show here that a regulated interaction of the endocytic adaptor RalBP1 with two synaptic proteins, the small GTPase RalA and the postsynaptic scaffolding protein PSD-95, controls NMDAR-dependent AMPAR endocytosis during LTD. NMDAR activation stimulates RalA, which binds and translocates widespread RalBP1 to synapses. In addition, NMDAR activation dephosphorylates RalBP1, promoting the interaction of RalBP1 with PSD-95. These two regulated interactions are required for NMDAR-dependent AMPAR endocytosis and LTD and are sufficient to induce AMPAR endocytosis in the absence of NMDAR activation. RalA in the basal state, however, maintains surface AMPARs. We propose that NMDAR activation brings RalBP1 close to PSD-95 to promote the interaction of RalBP1-associated endocytic proteins with PSD-95-associated AMPARs. This suggests that scaffolding proteins at specialized cellular junctions can switch their function from maintenance to endocytosis of interacting membrane proteins in a regulated manner.


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