Real-time visualization of mRNA synthesis during memory formation in live mice.

Memories are thought to be encoded in populations of neurons called memory trace or engram cells. However, little is known about the dynamics of these cells because of the difficulty in real-time monitoring of them over long periods of time in vivo. To overcome this limitation, we present a genetically encoded RNA indicator (GERI) mouse for intravital chronic imaging of endogenous Arc messenger RNA (mRNA)-a popular marker for memory trace cells. We used our GERI to identify Arc-positive neurons in real time without the delay associated with reporter protein expression in conventional approaches. We found that the Arc-positive neuronal populations rapidly turned over within 2 d in the hippocampal CA1 region, whereas ∼4% of neurons in the retrosplenial cortex consistently expressed Arc following contextual fear conditioning and repeated memory retrievals. Dual imaging of GERI and a calcium indicator in CA1 of mice navigating a virtual reality environment revealed that only the population of neurons expressing Arc during both encoding and retrieval exhibited relatively high calcium activity in a context-specific manner. This in vivo RNA-imaging approach opens the possibility of unraveling the dynamics of the neuronal population underlying various learning and memory processes.

Differential Expression of Presynaptic Munc13-1 and Munc13-2 in Mouse Hippocampus Following Ethanol Drinking.

The Munc13 family of proteins is critically involved in synaptic vesicle priming and release in glutamatergic neurons in the brain. Munc13-1 binds to alcohol and, in Drosophila, modulates sedation sensitivity and self-administration. We examined the effect of alcohol consumption on the expression of Munc13-1 and Munc13-2, NMDA receptor subunits GluN1, GluN2A and GluN2B in the hippocampus-derived HT22 cells, hippocampal primary neuron culture, and wild-type and Munc13-1+/- male mouse hippocampus after ethanol consumption (Drinking in the Dark (DID) paradigm). In HT22 cells, Munc13-1 was upregulated following 25 mM ethanol treatment for 24 h. In the primary neuronal culture, however, the expression of both Munc13-1 and Munc13-2 increased after ethanol exposure. While Munc13-1 was upregulated in the hippocampus, Munc13-2 was downregulated following DID. This differential effect was found in the CA1 subfield of the hippocampus. Although Munc13-1+/- mice had approximately 50% Munc13-1 expression compared to wild-type, it was nonetheless significantly increased following DID. Munc13-1 and Munc13-2 were expressed in vesicular glutamate transporter1 (VGLUT1) immunoreactive neurons in the hippocampus, but ethanol did not alter the expression of VGLUT1. The NMDA receptor subunits, GluN1, GluN2A and GluN2B were upregulated in the hippocampal primary culture and in the CA1. Ethanol exerts a differential effect on the expression of Munc13-1 and Munc13-2 in the CA1 in male mice. Our study also found that ethanol's effect on Munc13 expression is dependent on the experimental paradigm, and both Munc13-1 and Munc13-2 could contribute to the ethanol-induced augmentation of glutamatergic neurotransmission.

Targeting hippocampal amyloidogenesis with SV2A protein modulator levetiracetam.

Cerebral amyloid ß (Aß) proteostasis is compromised under neuronal overexcitation, long-term neuroinflammation and brain aging. Using the animal model of LPS-induced neuroinflammation we demonstrated that treatment with levetiracetam, a specific modulator of synaptic vesicle glycoprotein SV2A, rescues abnormal synaptic vesicle (SV) fusion and neurotransmitter release, decreasing elevated hippocampal APP levels in vivo. Therapy with levetiracetam upregulates the SV2A in hippocampus and restores the level of apolipoprotein E, involved in brain Aß aggregation/clearance and resolution of inflammation. We demonstrated that oligomers of Aß1-42 and Aß1-40 peptides promote SV clustering, which reduces the rate and plateau level of subsequent homo- and heterotypic SNARE-mediated SV fusion. Oligomeric Aß1-42 lowered ΔpH gradient across the vesicular membrane, thus affecting their neurotransmitter storage capacity. In contrast, monomers of Aß1-42 and Aß1-40 had negligible impact on studied processes. Our data suggests that in the course of progression of neuroinflammation oligomeric forms of Aß1-42 and Aß1-40 can compromise the SV fusion machinery and that antiepileptic agent levetiracetam, acting on SV recycling and restricting overexcitation, is able to affect APP processing and Aß generation within the hippocampus in vivo.

Hepatocyte Nuclear Factor 4-α (HNF4α) controls the insulin resistance-induced pancreatic ß-cell mass expansion.

BACKGROUND: Regardless of the etiology, any type of DM presents a reduction of insulin-secreting cell mass, so it is important to investigate pathways that induce the increase of this cell mass. AIM: Based on the fact that (1) HNF4α is crucial for ß-cell proliferation, (2) DEX-induced IR promotes ß-cell mass expansion, and (3) the stimulation of ß-cell mass expansion may be an important target for DM therapies, we aimed to investigate whether DEX-induced proliferation of ß pancreatic cells is dependent on HNF4α. METHODS: We used WildType (WT) and Knockout (KO) mice for HNF4-α, treated or not with 100 mg/Kg/day of DEX, for 5 consecutive days. One day after the last injection of DEX the IR was confirmed by ipITT and the mice were euthanized for pancreas removal. RESULTS: In comparison to WT, KO mice presented increased glucose tolerance, lower fasting glucose and increased glucose-stimulates insulin secretion (GSIS). DEX induced IR in both KO and WT mice. In addition, DEX-induced ß-cell mass expansion and an increase in the Ki67 immunostaining were observed only in WT mice, evidencing that IR-induced ß-cell mass expansion is dependent on HNF4α. Also, we observed that DEX-treatment, in an HNF4α-dependent way, promoted an increase in PDX1, PAX4 and NGN3 gene expression. CONCLUSIONS: Our results strongly suggest that DEX-induced IR promotes ß-cell mass expansion through processes of proliferation and neogenesis that depend on the HNF4α activity, pointing to HNF4α as a possible therapeutic target in DM treatment.

LncRNA CEBPA-AS1 alleviates cerebral ischemia-reperfusion injury by sponging miR-340-5p regulating APPL1/LKB1/AMPK pathway.

Long non-coding RNAs (lncRNAs) regulate neurological damage in cerebral ischemia-reperfusion injury (CIRI). This study aimed to investigate the biological roles of lncRNA CEBPA-AS1 in CIRI. Middle cerebral artery occlusion and ischemia-reperfusion injury (MCAO/IR) rat model and oxygen-glucose deprivation and reoxygenation (OGD/R) cell lines were generated; the expression of CEBPA-AS1 was evaluated by qRT-PCR. The effects of CEBPA-AS1 on cell apoptosis and nerve damage were examined. The downstream microRNA (miRNA) and mRNA of CEBPA-AS1 were predicted and verified. We found that overexpression of CEBPA-AS1 could attenuate MCAO/IR-induced nerve damage and neuronal apoptosis in the rat model. Knockdown of CEBPA-AS1 aggravated cell apoptosis and enhanced the production of LDH and MDA in the OGD/R cells. Upon examining the molecular mechanisms, we found that CEBPA-AS1 stimulated APPL1 expression by combining with miR-340-5p, thereby regulating the APPL1/LKB1/AMPK pathway. In the rescue experiments, CEBPA-AS1 overexpression was found to attenuate OGD/R-induced cell apoptosis and MCAO/IR induced nerve damage, while miR-340-5p reversed these effects of CEBPA-AS1. In conclusion, CEBPA-AS1 could decrease CIRI by sponging miR-340-5, regulating the APPL1/LKB1/AMPK pathway.

Dihydroartemisinin alleviates morphine-induced neuroinflammation in BV-2 cells.

Morphine tolerance poses a great challenge for clinicians, whose pathogenesis has a close connection with microglial activation and neuroinflammation. Dihydroartemisinin (DHA) that derives from artemisinin, may serve as a potential anti-inflammatory drug. In this study, the effects as well as the underlying mechanism of DHA on suppressing microglial activation and neuroinflammation were explored. The microglial cell line BV-2 cells were induced by morphine and treated with DHA or minocycline. With the application of CCK-8, the cell viability was detected. Western blot was employed to assess the expressions of Ki67, IBa-1, and TLR4 and quantitative real-time PCR (qRT-PCR) was adopted to evaluate miRNA-16 (miR-16) expression. With the adoption of ELISA kits and qRT-PCR, the release of inflammatory cytokines was evaluated. Besides, luciferase reporter assay was applied to testify the binding relationship between miR-16 and TLR4. NF-κB expression was measured by immunofluorescence. DHA reduced cell viability and decreased protein expression of Ki67 and IBa-1 in morphine-induced BV-2 cells. Additionally, DHA contributed to the declined release of pro-inflammatory cytokines. miR-16 was down-regulated by morphine but was up-regulated by DHA concentration-dependently in BV-2 cells. The inhibition of miR-16 partly abolished the inhibitory effects of DHA on morphine-induced microglial activation and neuroinflammation. Moreover, TLR4 was found to be bound to miR-16, and the inhibitory effect of DHA on TLR4/NF-κB was partly reversed by miR-16 inhibition. In conclusion, DHA remarkably suppressed microglial activation and neuroinflammation through regulating miR-16-mediated TLR4/NF-κB signaling. This study may provide a new solution to improve clinical analgesic efficacy of morphine.

Rejuvenating the Aging Heart by Enhancing the Expression of the Cisd2 Prolongevity Gene.

Aging is the major risk factor for cardiovascular disease, which is the leading cause of mortality worldwide among aging populations. Cisd2 is a prolongevity gene that mediates lifespan in mammals. Previously, our investigations revealed that a persistently high level of Cisd2 expression in mice is able to prevent age-associated cardiac dysfunction. This study was designed to apply a genetic approach that induces cardiac-specific Cisd2 overexpression (Cisd2 icOE) at a late-life stage, namely a time point immediately preceding the onset of old age, and evaluate the translational potential of this approach. Several discoveries are pinpointed. Firstly, Cisd2 is downregulated in the aging heart. This decrease in Cisd2 leads to cardiac dysfunction and impairs electromechanical performance. Intriguingly, Cisd2 icOE prevents an exacerbation of age-associated electromechanical dysfunction. Secondly, Cisd2 icOE ameliorates cardiac fibrosis and improves the integrity of the intercalated discs, thereby reversing various structural abnormalities. Finally, Cisd2 icOE reverses the transcriptomic profile of the aging heart, changing it from an older-age pattern to a younger pattern. Intriguingly, Cisd2 icOE modulates a number of aging-related pathways, namely the sirtuin signaling, autophagy, and senescence pathways, to bring about rejuvenation of the heart as it enters old age. Our findings highlight Cisd2 as a novel molecular target for developing therapies targeting cardiac aging.

Sex-specific effects of metformin and liraglutide on renal pathology and expression of connexin 45 and pannexin 1 following long-term high-fat high-sugar diet.

The comparative effects of the two commonly used antidiabetic drugs metformin and liraglutide on renal pathology and expression of connexin 45 (Cx45) and pannexin 1 (Panx1) in adult obese rats fed high-fat high-sugar diet (HFHSD) were studied. Considering recent data on the profound influence of sex on metformin and liraglutide effects, we compared the effects of both drugs between male and female animals. 44-week-old Sprague-Dawley rats were separated into 4 groups that were fed: standard diet, HFHSD, HFHSD treated with metformin (s.c., 50 mg/kg/day) and HFHSD treated with liraglutide (s.c., 0.3 mg/kg/day). Treatment with metformin or liraglutide lasted for 14 weeks. Histology and immunohistochemistry were performed to quantify renal pathological changes and Cx45 and Panx1 expression. HFHSD caused thickening of the Bowman's capsule (BC). Both metformin and liraglutide failed to ameliorate the BC thickening; metformin even worsened it. Effects on the tubulointerstitial fibrosis score, BC thickness and Cx45 and Panx1 expression were sex-dependent. We found a 50% increase in mitochondria in proximal tubules of metformin- and liraglutide-treated HFHSD-fed rats, but these effects were not dependent on the sex. This is a first study showing that the effects of metformin and liraglutide on kidney pathology in rats fed HFHSD are mostly sex-dependent and that these effects are not necessarily beneficial. Both drugs changed the Cx45 and Panx 1 expression; hence their effects could be related to amelioration of disruptions in intercellular communication.

Curcumin mediates repulsive guidance molecule B (RGMb) in the treatment mechanism of renal fibrosis induced by unilateral ureteral obstruction.

In this study, we explored the role and mechanism of repulsive guidance molecule B (RGMb, also known as Dragon) in the protective effects of curcumin against renal fibrosis and verified Dragon's effect on renal tubular epithelial cell apoptosis and cell programmability. Unilateral ureteral obstruction (UUO) was surgically induced in rats to establish a model of renal interstitial fibrosis (RIF). The rats were then treated with curcumin. Curcumin prominently decreased the serum creatinine (SCr) and blood urea nitrogen (BUN) levels, and also improved the tubular injury in the UUO-induced rats. Curcumin significantly downregulated the TGF-ß1, P-Smad2/3, cleaved caspase-3, cleaved caspase-8 and Dragon levels. Dragon knockdown also markedly reduced the TGF-ß1, P-Smad2/3, Smad2/3, cleaved caspase-3, cleaved caspase-8, fibronectin, collagen I, collagen IV, vimentin, and α-SMA expression levels. Conversely, Dragon overexpression caused higher expression levels of these proteins, and curcumin reversed this effect. Furthermore, Dragon knockdown increased the E-cadherin levels, whereas Dragon overexpression decreased these levels. Overexpressing Dragon significantly decreased the cell viability, and curcumin reversed this effect. In conclusion, curcumin acted on Dragon and attenuated RIF in UUO rat models. Curcumin downregulated the TGF-ß1/Smad signaling pathway and inhibited Dragon and fibrogenic molecules in both rats and HK-2 cells.

Seasonal regulation of singing-driven gene expression associated with song plasticity in the canary, an open-ended vocal learner.

Songbirds are one of the few animal taxa that possess vocal learning abilities. Different species of songbirds exhibit species-specific learning programs during song acquisition. Songbirds with open-ended vocal learning capacity, such as the canary, modify their songs during adulthood. Nevertheless, the neural molecular mechanisms underlying open-ended vocal learning are not fully understood. We investigated the singing-driven expression of neural activity-dependent genes (Arc, Egr1, c-fos, Nr4a1, Sik1, Dusp6, and Gadd45ß) in the canary to examine a potential relationship between the gene expression level and the degree of seasonal vocal plasticity at different ages. The expression of these genes was differently regulated throughout the critical period of vocal learning in the zebra finch, a closed-ended song learner. In the canary, the neural activity-dependent genes were induced by singing in the song nuclei throughout the year. However, in the vocal motor nucleus, the robust nucleus of the arcopallium (RA), all genes were regulated with a higher induction rate by singing in the fall than in the spring. The singing-driven expression of these genes showed a similar induction rate in the fall between the first year juvenile and the second year adult canaries, suggesting a seasonal, not age-dependent, regulation of the neural activity-dependent genes. By measuring seasonal vocal plasticity and singing-driven gene expression, we found that in RA, the induction intensity of the neural activity-dependent genes was correlated with the state of vocal plasticity. These results demonstrate a correlation between vocal plasticity and the singing-driven expression of neural activity-dependent genes in RA through song development, regardless of whether a songbird species possesses an open- or closed-ended vocal learning capacity.

Genetically identified amygdala-striatal circuits for valence-specific behaviors.

The basolateral amygdala (BLA) plays essential roles in behaviors motivated by stimuli with either positive or negative valence, but how it processes motivationally opposing information and participates in establishing valence-specific behaviors remains unclear. Here, by targeting Fezf2-expressing neurons in the BLA, we identify and characterize two functionally distinct classes in behaving mice, the negative-valence neurons and positive-valence neurons, which innately represent aversive and rewarding stimuli, respectively, and through learning acquire predictive responses that are essential for punishment avoidance or reward seeking. Notably, these two classes of neurons receive inputs from separate sets of sensory and limbic areas, and convey punishment and reward information through projections to the nucleus accumbens and olfactory tubercle, respectively, to drive negative and positive reinforcement. Thus, valence-specific BLA neurons are wired with distinctive input-output structures, forming a circuit framework that supports the roles of the BLA in encoding, learning and executing valence-specific motivated behaviors.

Dynamic Changes of Brain Cilia Transcriptomes across the Human Lifespan.

Almost all brain cells contain primary cilia, antennae-like microtubule sensory organelles, on their surface, which play critical roles in brain functions. During neurodevelopmental stages, cilia are essential for brain formation and maturation. In the adult brain, cilia play vital roles as signaling hubs that receive and transduce various signals and regulate cell-to-cell communications. These distinct roles suggest that cilia functions, and probably structures, change throughout the human lifespan. To further understand the age-dependent changes in cilia roles, we identified and analyzed age-dependent patterns of expression of cilia's structural and functional components across the human lifespan. We acquired cilia transcriptomic data for 16 brain regions from the BrainSpan Atlas and analyzed the age-dependent expression patterns using a linear regression model by calculating the regression coefficient. We found that 67% of cilia transcripts were differentially expressed genes with age (DEGAs) in at least one brain region. The age-dependent expression was region-specific, with the highest and lowest numbers of DEGAs expressed in the ventrolateral prefrontal cortex and hippocampus, respectively. The majority of cilia DEGAs displayed upregulation with age in most of the brain regions. The transcripts encoding cilia basal body components formed the majority of cilia DEGAs, and adjacent cerebral cortices exhibited large overlapping pairs of cilia DEGAs. Most remarkably, specific α/ß-tubulin subunits (TUBA1A, TUBB2A, and TUBB2B) and SNAP-25 exhibited the highest rates of downregulation and upregulation, respectively, across age in almost all brain regions. α/ß-tubulins and SNAP-25 expressions are known to be dysregulated in age-related neurodevelopmental and neurodegenerative disorders. Our results support a role for the high dynamics of cilia structural and functional components across the lifespan in the normal physiology of brain circuits. Furthermore, they suggest a crucial role for cilia signaling in the pathophysiological mechanisms of age-related psychiatric/neurological disorders.

Prognostic efficacy of the RTN1 gene in patients with diffuse large B-cell lymphoma.

Gene expression profiling has been vastly used to extract the genes that can predict the clinical outcome in patients with diverse cancers, including diffuse large B-cell lymphoma (DLBCL). With the aid of bioinformatics and computational analysis on gene expression data, various prognostic gene signatures for DLBCL have been recently developed. The major drawback of the previous signatures is their inability to correctly predict survival in external data sets. In other words, they are not reproducible in other datasets. Hence, in this study, we sought to determine the gene(s) that can reproducibly and robustly predict survival in patients with DLBCL. Gene expression data were extracted from 7 datasets containing 1636 patients (GSE10846 [n = 420], GSE31312 [n = 470], GSE11318 [n = 203], GSE32918 [n = 172], GSE4475 [n = 123], GSE69051 [n = 157], and GSE34171 [n = 91]). Genes significantly associated with overall survival were detected using the univariate Cox proportional hazards analysis with a P value < 0.001 and a false discovery rate (FDR) < 5%. Thereafter, significant genes common between all the datasets were extracted. Additionally, chromosomal aberrations in the corresponding region of the final common gene(s) were evaluated as copy number alterations using the single nucleotide polymorphism (SNP) data of 570 patients with DLBCL (GSE58718 [n = 242], GSE57277 [n = 148], and GSE34171 [n = 180]). Our results indicated that reticulon family gene 1 (RTN1) was the only gene that met our rigorous pipeline criteria and associated with a favorable clinical outcome in all the datasets (P < 0.001, FDR < 5%). In the multivariate Cox proportional hazards analysis, this gene remained independent of the routine international prognostic index components (i.e., age, stage, lactate dehydrogenase level, Eastern Cooperative Oncology Group [ECOG] performance status, and number of extranodal sites) (P < 0.0001). Furthermore, no significant chromosomal aberration was found in the RTN1 genomic region (14q23.1: Start 59,595,976/End 59,870,966).

GDF11 expressed in the adult brain negatively regulates hippocampal neurogenesis.

Growth differentiation factor 11 (GDF11) is a transforming factor-ß superfamily member that functions as a negative regulator of neurogenesis during embryonic development. However, when recombinant GDF11 (rGDF11) is administered systemically in aged mice, it promotes neurogenesis, the opposite of its role during development. The goal of the present study was to reconcile this apparent discrepancy by performing the first detailed investigation into the expression of endogenous GDF11 in the adult brain and its effects on neurogenesis. Using quantitative histological analysis, we observed that Gdf11 is most highly expressed in adult neurogenic niches and non-neurogenic regions within the hippocampus, choroid plexus, thalamus, habenula, and cerebellum. To investigate the role of endogenous GDF11 during adult hippocampal neurogenesis, we generated a tamoxifen inducible mouse that allowed us to reduce GDF11 levels. Depletion of Gdf11 during adulthood increased proliferation of neural progenitors and decreased the number of newborn neurons in the hippocampus, suggesting that endogenous GDF11 remains a negative regulator of hippocampal neurogenesis in adult mice. These findings further support the idea that circulating systemic GDF11 and endogenously expressed GDF11 in the adult brain have different target cells or mechanisms of action. Our data describe a role for GDF11-dependent signaling in adult neurogenesis that has implications for how GDF11 may be used to treat CNS disease.

Similarities of developmental gene expression changes in the brain between human and experimental animals: rhesus monkey, mouse, Zebrafish, and Drosophila.

AIM: Experimental animals, such as non-human primates (NHPs), mice, Zebrafish, and Drosophila, are frequently employed as models to gain insights into human physiology and pathology. In developmental neuroscience and related research fields, information about the similarities of developmental gene expression patterns between animal models and humans is vital to choose what animal models to employ. Here, we aimed to statistically compare the similarities of developmental changes of gene expression patterns in the brains of humans with those of animal models frequently used in the neuroscience field. METHODS: The developmental gene expression datasets that we analyzed consist of the fold-changes and P values of gene expression in the brains of animals of various ages compared with those of the youngest postnatal animals available in the dataset. By employing the running Fisher algorithm in a bioinformatics platform, BaseSpace, we assessed similarities between the developmental changes of gene expression patterns in the human (Homo sapiens) hippocampus with those in the dentate gyrus (DG) of the rhesus monkey (Macaca mulatta), the DG of the mouse (Mus musculus), the whole brain of Zebrafish (Danio rerio), and the whole brain of Drosophila (D. melanogaster). RESULTS: Among all possible comparisons of different ages and animals in developmental changes in gene expression patterns within the datasets, those between rhesus monkeys and mice were highly similar to those of humans with significant overlap P-value as assessed by the running Fisher algorithm. There was the highest degree of gene expression similarity between 40-59-year-old humans and 6-12-year-old rhesus monkeys (overlap P-value = 2.1 × 10- 72). The gene expression similarity between 20-39-year-old humans and 29-day-old mice was also significant (overlap P = 1.1 × 10- 44). Moreover, there was a similarity in developmental changes of gene expression patterns between 1-2-year-old Zebrafish and 40-59-year-old humans (Overlap P-value = 1.4 × 10- 6). The overlap P-value of developmental gene expression patterns between Drosophila and humans failed to reach significance (30 days Drosophila and 6-11-year-old humans; overlap P-value = 0.0614). CONCLUSIONS: These results indicate that the developmental gene expression changes in the brains of the rhesus monkey, mouse, and Zebrafish recapitulate, to a certain degree, those in humans. Our findings support the idea that these animal models are a valid tool for investigating the development of the brain in neurophysiological and neuropsychiatric studies.

Tianeptine modulates synaptic vesicle dynamics and favors synaptic mitochondria processes in socially isolated rats.

Deregulation of synaptic function and neurotransmission has been linked with the development of major depression disorder (MDD). Tianeptine (Tian) has been used as antidepressant with anxiolytic properties and recently as a nootropic to improve cognitive performance, but its mechanism of action is unknown. We conducted a proteomic study on the hippocampal synaptosomal fractions of adult male Wistar rats exposed to chronic social isolation (CSIS, 6 weeks), an animal model of depression and after chronic Tian treatment in controls (nootropic effect) and CSIS-exposed rats (lasting 3 weeks of 6-week CSIS) (therapeutic effect). Increased expression of Syn1 and Camk2-related neurotransmission, vesicle transport and energy processes in Tian-treated controls were found. CSIS led to upregulation of proteins associated with actin cytoskeleton, signaling transduction and glucose metabolism. In CSIS rats, Tian up-regulated proteins involved in mitochondrial energy production, mitochondrial transport and dynamics, antioxidative defense and glutamate clearance, while attenuating the CSIS-increased glycolytic pathway and cytoskeleton organization proteins expression and decreased the expression of proteins involved in V-ATPase and vesicle endocytosis. Our overall findings revealed that synaptic vesicle dynamics, specifically exocytosis, and mitochondria-related energy processes might be key biological pathways modulated by the effective nootropic and antidepressant treatment with Tian and be a potential target for therapeutic efficacy of the stress-related mood disorders.

Histone modification of pain-related gene expression in spinal cord neurons under a persistent postsurgical pain-like state by electrocautery.

Chronic postsurgical pain (CPSP) is a serious problem. We developed a mouse model of CPSP induced by electrocautery and examined the mechanism of CPSP. In this mouse model, while both incision and electrocautery each produced acute allodynia, persistent allodynia was only observed after electrocautery. Under these conditions, we found that the mRNA levels of Small proline rich protein 1A (Sprr1a) and Annexin A10 (Anxa10), which are the key modulators of neuropathic pain, in the spinal cord were more potently and persistently increased by electrocautery than by incision. Furthermore, these genes were overexpressed almost exclusively in chronic postsurgical pain-activated neurons. This event was associated with decreased levels of tri-methylated histone H3 at Lys27 and increased levels of acetylated histone H3 at Lys27 at their promoter regions. On the other hand, persistent allodynia and overexpression of Sprr1a and Anxa10 after electrocautery were dramatically suppressed by systemic administration of GSK-J4, which is a selective H3K27 demethylase inhibitor. These results suggest that the effects of electrocautery contribute to CPSP along with synaptic plasticity and epigenetic modification.

Slo2/KNa Channels in Drosophila Protect against Spontaneous and Induced Seizure-like Behavior Associated with an Increased Persistent Na+ Current.

Na+ sensitivity is a unique feature of Na+-activated K+ (KNa) channels, making them naturally suited to counter a sudden influx in Na+ ions. As such, it has long been suggested that KNa channels may serve a protective function against excessive excitation associated with neuronal injury and disease. This hypothesis, however, has remained largely untested. Here, we examine KNa channels encoded by the Drosophila Slo2 (dSlo2) gene in males and females. We show that dSlo2/KNa channels are selectively expressed in cholinergic neurons in the adult brain, as well as in glutamatergic motor neurons, where dampening excitation may function to inhibit global hyperactivity and seizure-like behavior. Indeed, we show that effects of feeding Drosophila a cholinergic agonist are exacerbated by the loss of dSlo2/KNa channels. Similar to mammalian Slo2/KNa channels, we show that dSlo2/KNa channels encode a TTX-sensitive K+ conductance, indicating that dSlo2/KNa channels can be activated by Na+ carried by voltage-dependent Na+ channels. We then tested the role of dSlo2/KNa channels in established genetic seizure models in which the voltage-dependent persistent Na+ current (INap) is elevated. We show that the absence of dSlo2/KNa channels increased susceptibility to mechanically induced seizure-like behavior. Similar results were observed in WT flies treated with veratridine, an enhancer of INap Finally, we show that loss of dSlo2/KNa channels in both genetic and pharmacologically primed seizure models resulted in the appearance of spontaneous seizures. Together, our results support a model in which dSlo2/KNa channels, activated by neuronal overexcitation, contribute to a protective threshold to suppress the induction of seizure-like activity.SIGNIFICANCE STATEMENT Slo2/KNa channels are unique in that they constitute a repolarizing K+ pore that is activated by the depolarizing Na+ ion, making them naturally suited to function as a protective "brake" against overexcitation and Na+ overload. Here, we test this hypothesis in vivo by examining how a null mutation of the Drosophila Slo2 (dSlo2)/KNa gene affects seizure-like behavior in genetic and pharmacological models of epilepsy. We show that indeed the loss of dSlo2/KNa channels results in increased incidence and severity of induced seizure behavior, as well as the appearance of spontaneous seizure activity. Our results advance our understanding of neuronal excitability and protective mechanisms that preserve normal physiology and the suppression of seizure susceptibility.

RGC-32 Acts as a Hub to Regulate the Transcriptomic Changes Associated With Astrocyte Development and Reactive Astrocytosis.

Response Gene to Complement 32 (RGC-32) is an important mediator of the TGF-ß signaling pathway, and an increasing amount of evidence implicates this protein in regulating astrocyte biology. We showed recently that spinal cord astrocytes in mice lacking RGC-32 display an immature phenotype reminiscent of progenitors and radial glia, with an overall elongated morphology, increased proliferative capacity, and increased expression of progenitor markers when compared to their wild-type (WT) counterparts that make them incapable of undergoing reactive changes during the acute phase of experimental autoimmune encephalomyelitis (EAE). Here, in order to decipher the molecular networks underlying RGC-32's ability to regulate astrocytic maturation and reactivity, we performed next-generation sequencing of RNA from WT and RGC-32 knockout (KO) neonatal mouse brain astrocytes, either unstimulated or stimulated with the pleiotropic cytokine TGF-ß. Pathway enrichment analysis showed that RGC-32 is critical for the TGF-ß-induced up-regulation of transcripts encoding proteins involved in brain development and tissue remodeling, such as axonal guidance molecules, transcription factors, extracellular matrix (ECM)-related proteins, and proteoglycans. Our next-generation sequencing of RNA analysis also demonstrated that a lack of RGC-32 results in a significant induction of WD repeat and FYVE domain-containing protein 1 (Wdfy1) and stanniocalcin-1 (Stc1). Immunohistochemical analysis of spinal cords isolated from normal adult mice and mice with EAE at the peak of disease showed that RGC-32 is necessary for the in vivo expression of ephrin receptor type A7 in reactive astrocytes, and that the lack of RGC-32 results in a higher number of homeodomain-only protein homeobox (HOPX)+ and CD133+ radial glia cells. Collectively, these findings suggest that RGC-32 plays a major role in modulating the transcriptomic changes in astrocytes that ultimately lead to molecular programs involved in astrocytic differentiation and reactive changes during neuroinflammation.

Complement Component C3 Loss leads to Locomotor Deficits and Altered Cerebellar Internal Granule Cell In Vitro Synaptic Protein Expression in C57BL/6 Mice.

Complement component 3 (C3) expression is increased in the cerebellum of aging mice that demonstrate locomotor impairments and increased excitatory synapse density. However, C3 regulation of locomotion, as well as C3 roles in excitatory synapse function, remains poorly understood. Here, we demonstrate that constitutive loss of C3 function in mice evokes a locomotor phenotype characterized by decreased speed, increased active state locomotor probability, and gait ataxia. C3 loss does not alter metabolism or body mass composition. No evidence of significant muscle weakness or degenerative arthritis was found in C3 knockout mice to explain decreased gait speeds. In an enriched primary cerebellar granule cell culture model, loss of C3 protein results in increased excitatory synaptic density and increased response to KCl depolarization. Our analysis of excitatory synaptic density in the cerebellar internal granule cell and molecular layers did not demonstrate increased synaptic density in vivo, suggesting the presence of compensatory mechanisms regulating synaptic development. Functional deficits in C3 knockout mice are therefore more likely to result from altered synaptic function and/or connectivity than gross synaptic deficits. Our data demonstrate a novel role for complement proteins in cerebellar regulation of locomotor output and control.