Types Of Subunits Research Articles

Kir6.1, a component of an ATP-sensitive potassium channel, regulates natural killer cell development

IntroductionInvolved in immunity and reproduction, natural killer (NK) cells offer opportunities to develop new immunotherapies to treat infections and cancer or to alleviate pregnancy complications. Most current strategies use cytokines or antibodies to enhance NK-cell function, but none use ion channel modulators, which are widely used in clinical practice to treat hypertension, diabetes, epilepsy, and other conditions. Little is known about ion channels in NK cells. ResultsWe show that Kcnj8, which codes for the Kir6.1 subunit of a certain type of ATP-sensitive potassium (KATP) channel, is highly expressed in murine splenic and uterine NK cells compared to other K+ channels previously identified in NK cells. Kcnj8 expression is highest in the most mature subset of splenic NK cells (CD27-/CD11b+) and in NKG2A+ or Ly49C/I+ educated uterine NK cells. Using patch clamping, we show that a subset of NK cells expresses a current sensitive to the Kir6.1 blocker PNU-37883A. Kcnj8 does not participate in NK cell degranulation in response to tumor cells in vitro or rejection of tumor cells in vivo, or IFN-γ release. Transcriptomics show that genes previously implicated in NK cell development are amongst those differentially expressed in CD27-/CD11b+ NK cells deficient for Kcnj8. Indeed, we found that mice with NK-cell specific Kcnj8 gene ablation have fewer CD27-/CD11b+ and KLRG-1+ NK cells in the bone barrow and spleen. DiscussionThese results show that the KATP subunit Kir6.1 has a key role in NK-cell development.

BHLHE40-mediated transcriptional activation of GRIN2D in gastric cancer is involved in metabolic reprogramming.

Gastric cancer (GC) is the third leading cause of death in developed countries. The reprogramming of energy metabolism represents a hallmark of cancer, particularly amplified dependence on aerobic glycolysis. Here, we aimed to illustrate the functional role of glutamate ionotropic receptor N-methyl-D-aspartate type subunit 2D (GRIN2D) in the regulation of glycolysis in GC and the mechanisms involved. Differentially expressed genes were analyzed using the GEO and GEPIA databases, followed by prognostic value prediction using the Kaplan-Meier Plotter database. The effect of GRIN2D knockdown on the malignant behavior and glycolysis of GC cells was explored. GRIN2D expression was upregulated in GC cells and promoted the malignant behavior of GC cells by activating glycolysis. Class E basic helix-loop-helix protein 40 (BHLHE40) was overexpressed in GC cells and mediated transcriptional activation of GRIN2D. The anti-tumor effects of BHLHE40 knockdown on GC cells in vitro and in vivo were reversed by GRIN2D overexpression. Knockdown of GRIN2D or BHLHE40 downregulated the expression of mRNA of electron transport chain subunits and phosphorylation of p38 MARK and inhibited calcium efflux in GC cells. Overexpression of GRIN2D promoted calcium efflux, phosphorylation of p38 MARK protein, and proliferation of GES1 cells. Altogether, the findings derived from this study suggest that BHLHE40 knockdown suppresses the growth, mobility, and glycolysis of GC cells by inhibiting GRIN2D transcription and disrupting the BHLHE40/GRIN2D axis may be an attractive therapeutic strategy for GC.

CNSC-39. INTEGRATED CLINICAL GENETIC ANALYSIS REVEALS NEUROTRANSMITTER RECEPTOR DYSREGULATION IN MENINGIOMAS CAUSING SEIZURE

Abstract Molecular correlates of seizures in meningioma remain unexplored. Previously, we identified MenG molecular grouping, wherein MenG C meningiomas recur more than MenG A or B. We therefore sought to identify molecular and clinical drivers of seizures in meningioma. We identified 144 primary supratentorial meningiomas, excluding those with pre-existing epilepsy. Whole exome sequencing assessed somatic mutation burden. Bulk RNA-sequencing identified differentially expressed genes and gene ontologies (GO). Immunohistochemistry confirmed protein levels. No differences in canonical gene mutation burden (NF2, TRAF7, AKT1, KLF4, SMO, SMARC) was found between seizure and non-seizure groups. MenG C tumors had higher seizure incidence compared to MenG A or B (p=0.03). Seizure causing meningiomas, though extra-axial, exhibited dysregulated neuronal signaling genes. GABAA receptor subunit genes GABRA3 and GABRG1 were downregulated in tumors causing seizure (Log2FC=-1.67, padj=0.014; Log2FC=-2.24, padj=0.009). Immunohistochemistry confirmed expression of GABRB2 subunit, the first documentation of GABA receptor expression in meningiomas. Neuropeptide Y Receptor Y1 (NPY1R) is downregulated in seizure causing meningiomas (Log2FC=-1.64, padj=0.002). NPY1R loss correlates is observed in mesial temporal lobe epilepsy and post-electroconvulsive shock mouse brains. In GO analysis, the terms “GABA signaling pathway,” “neuropeptide signaling,” “excitatory postsynaptic membrane potential,” and “ionotropic glutamate pathway,” were downregulated in meningiomas with seizure (padj<0.05). We assessed which alterations within MenG C tumors caused seizures by identifying genes associated with both seizure presentation and MenG C classification. Glutamate ionotropic receptor AMPA type subunit 1 (GRIA1) is downregulated in MenG C tumors (Log2FC=-2.29, padj=6.02E-07) and seizure causing tumors (Log2FC=-1.75, padj=0.03). Clinically, patients experiencing pre-operative seizures more frequently had cerebral edema, non-homogenous enhancement, intratumoral calcification, higher MIB-1, atypical grade 1, reduced GCS, and ER presentation; they were less likely to have incidental or headache presentation (p<0.05 for all). MenG classification predicts seizure presentation whereas somatic mutation status does not. Meningiomas causing seizures show pathologic neurotransmitter receptor dysregulation.

TMIC-18. ROLE OF NEUROTRANSMITTERS IN GLIOBLASTOMA PATHOPHYSIOLOGY: EMERGING INSIGHTS

Abstract INTRODUCTION Glioblastoma (GBM) are the most common primary brain tumor in adults associated with a dismal patient outcome. While it is well-known that glutamatergic neurons can form functional synapses with glioblastoma cells to enhance tumor growth, lesser is known about the effects of activity of other neuronal types on glioblastoma biology, especially among different glioblastoma molecular subtypes. Here, we examined the effects of various neurotransmitters on the growth of glioblastoma cells characterized as classical, proneural and mesenchymal subtypes. METHODS Patient-derived glioblastoma cell lines were exposed to varying concentrations of different neurotransmitters and assessed for cell viability using CCK-8 assay. Transcriptomic data from TCGA (The Cancer Genome Atlas) database was analyzed for correlation of expression of neurotransmitter receptors (NTRs) with patient survival. Using IVY-GAP database, we compared the expression of NTRs at leading-edge versus tumor core of tumors to assess their possible involvement in cell migration and microenvironmental interactions. RESULTS Consistent with previous findings, we observed an increase in cell viability in all GBM cell lines after being incubated with L-glutamate. The classical subtype has a stronger growth response to L-glutamate compared to the other two subtypes. TCGA data revealed the expression of GRIK4 (glutamate ionotropic receptor kainate type subunit 4) as highest in the classical subtype as well as inversely correlated with worse patient survival in this GBM subtype, as opposed to proneural or mesenchymal patient groups. CCK8 assay also suggested that acetylcholine and dopamine increase glioblastoma cell growth. A subset of cholinergic and glutamatergic receptors (CHRM1, GRM2) was found upregulated in infiltrating/leading-edge regions of glioblastoma tumors compared to the tumor core, suggesting possible involvement in glioblastoma-neuron interactions. CONCLUSION Our findings suggest that GBM subtypes may differentially leverage neuro-modulatory mechanisms to support their growth. Future studies will investigate the differential neuronal responses in GBM subtypes using pharmacological/genetic approaches.

Mathematical models of C-type and N-type inactivating heteromeric voltage gated potassium channels.

Voltage gated potassium channels can be composed of either four identical, or different, pore-forming protein subunits. While the voltage gated channels with identical subunits have been extensively studied both physiologically and mathematically, those with multiple subunit types, termed heteromeric channels, have not been. Here we construct, and explore the predictive outputs of, mechanistic models for heteromeric voltage gated potassium channels that possess either N-type or C-type inactivation kinetics. For both types of inactivation, we first build Markov models of four identical pore-forming inactivating subunits. Combining this with previous results regarding non-inactivating heteromeric channels, we are able to define models for heteromeric channels containing both non-inactivating and inactivating subunits of any ratio. We simulate each model through three unique voltage clamp protocols to identify steady state properties. In doing so, we generate predictions about the impact of adding additional inactivating subunits on a total channel's kinetics. We show that while N-type inactivating subunits appear to have a non-linear impact on the level of inactivation the channel experiences, the effect of C-type inactivating subunits is almost linear. Finally, to combat the computational issues of working with a large number of state variables we define model reductions for both types of heteromeric channels. For the N-type heteromers we derive a quasi-steady-state approximation and indicate where the approximation is appropriate. With the C-type heteromers we are able to write an explicit model reduction bringing models of greater than 10 dimensions down to 2.

Cross-species single-cell spatial transcriptomic atlases of the cerebellar cortex.

The molecular and cellular organization of the primate cerebellum remains poorly characterized. We obtained single-cell spatial transcriptomic atlases of macaque, marmoset, and mouse cerebella and identified primate-specific cell subtypes, including Purkinje cells and molecular-layer interneurons, that show different expression of the glutamate ionotropic receptor Delta type subunit 2 (GRID2) gene. Distinct gene expression profiles were found in anterior, posterior, and vestibular regions in all species, whereas region-selective gene expression was predominantly observed in the granular layer of primates and in the Purkinje layer of mice. Gene expression gradients in the cerebellar cortex matched well with functional connectivity gradients revealed with awake functional magnetic resonance imaging, with more lobule-specific differences between primates and mice than between two primate species. These comprehensive atlases and comparative analyses provide the basis for understanding cerebellar evolution and function.

Proline substitutions in the ASIC1 β11-12 linker slow desensitization

Desensitization is a prominent feature of nearly all ligand-gated ion channels. Acid-sensing ion channels (ASICs) undergo desensitization within hundreds of milliseconds to seconds upon continual extracellular acidification. The ASIC mechanism of desensitization is primarily due to the isomerization or “flipping” of a short linker joining the 11th and 12th β sheets in the extracellular domain. In the resting and active states this β11-12 linker adopts an “upward” conformation while in the desensitized conformation the linker assumes a “downward” state. It is unclear if a single linker adopting the downward state is sufficient to desensitize the entire channel, or if all three are needed or some more complex scheme. To accommodate this downward state, specific peptide bonds within the linker adopt either trans-like or cis-like conformations. Since proline-containing peptide bonds undergo cis-trans isomerization very slowly, we hypothesized that introducing proline residues in the linker may slow or even abolish ASIC desensitization, potentially providing a valuable research tool. Proline substitutions in the chicken ASIC1 β11-12 linker (L414P and Y416P) slowed desensitization decays approximately 100- to 1000-fold as measured in excised patches. Both L414P and Y416P shifted the steady-state desensitization curves to more acidic pH values while activation curves and ion selectivity were largely unaffected (except for a left-shifted activation pH50 of L414P). To investigate the functional stoichiometry of desensitization in the trimeric ASIC, we created families of L414P and Y416P concatemers with zero, one, two, or three proline substitutions in all possible configurations. Introducing one or two L414P or Y416P substitutions only slightly attenuated desensitization, suggesting that conformational changes in the single remaining faster wild-type subunits were sufficient to desensitize the channel. These data highlight the unusual cis-trans isomerization mechanism of ASIC desensitization and support a model where ASIC desensitization requires only a single subunit.

Neuron-Derived Extracellular Vesicles miRNA Profiles Identify Children Who Experience Adverse Events after Ketamine Administration for Procedural Sedation.

Ketamine provides the highest safety profile among sedatives for procedural sedation and analgesia in the pediatric emergency setting. However, it can cause vomiting and recovery agitation. No studies have examined epigenetic factors, such as microRNAs, for predicting the occurrence of these adverse events. Neuronal-derived extracellular vesicle microRNA profiles were studied to predict the occurrence of ketamine-induced vomiting and recovery agitation in children. For this aim, a single-center prospective pharmacoepigenetic study was performed and 50 children who underwent procedural sedation with intravenous ketamine as the only sedative drug were enrolled between October 2019 and November 2022. MiRNA profiling in plasma neural-derived extracellular vesicles was analyzed through next-generation sequencing and measured before treatment with ketamine. Twenty-two patients experienced vomiting or recovery agitation. Among the 16 differentially expressed microRNAs, the upregulated miR-15a-5p and miR-484 targeted genes related to N-methyl-D-aspartate (NMDA) receptor activity, including glutamate ionotropic receptor NMDA type subunit 2A (GRIN2A). Preliminary data confirmed lower GRIN2A levels in patients who developed these events. Downregulated miR-126-3p and miR-24-3p targeted AMPA receptor-associated genes. Functional analyses of gene targets revealed the enrichment of glutamatergic and neurotrophins signaling. Recovery agitation was associated with this network. Vomiting was related to dopaminergic and cholinergic systems. Three miRNAs (miR-18a-3p, miR-484, and miR-548az-5p) were identified as predictive biomarkers (AUC 0.814; 95% CI: 0.632-0.956) for ketamine-induced vomiting and recovery agitation. MicroRNA profiles can predict the development of ketamine-induced vomiting or recovery agitation in children. This study contributes to the understanding of the mechanisms underlying ketamine-induced adverse events.

PI3K couples long-term synaptic potentiation with cofilin recruitment and actin polymerization in dendritic spines via its regulatory subunit p85α

Long-term synaptic plasticity is typically associated with morphological changes in synaptic connections. However, the molecular mechanisms coupling functional and structural aspects of synaptic plasticity are still poorly defined. The catalytic activity of type I phosphoinositide-3-kinase (PI3K) is required for specific forms of synaptic plasticity, such as NMDA receptor-dependent long-term potentiation (LTP) and mGluR-dependent long-term depression (LTD). On the other hand, PI3K signaling has been linked to neuronal growth and synapse formation. Consequently, PI3Ks are promising candidates to coordinate changes in synaptic strength with structural remodeling of synapses. To investigate this issue, we targeted individual regulatory subunits of type I PI3Ks in hippocampal neurons and employed a combination of electrophysiological, biochemical and imaging techniques to assess their role in synaptic plasticity. We found that a particular regulatory isoform, p85α, is selectively required for LTP. This specificity is based on its BH domain, which engages the small GTPases Rac1 and Cdc42, critical regulators of the actin cytoskeleton. Moreover, cofilin, a key regulator of actin dynamics that accumulates in dendritic spines after LTP induction, failed to do so in the absence of p85α or when its BH domain was overexpressed as a dominant negative construct. Finally, in agreement with this convergence on actin regulatory mechanisms, the presence of p85α in the PI3K complex determined the extent of actin polymerization in dendritic spines during LTP. Therefore, this study reveals a molecular mechanism linking structural and functional synaptic plasticity through the coordinate action of PI3K catalytic activity and a specific isoform of the regulatory subunits.

Kir6.1, a component of an ATP-sensitive potassium channel, regulates natural killer cell development.

Involved in immunity and reproduction, natural killer (NK) cells offer opportunities to develop new immunotherapies to treat infections and cancer or to alleviate pregnancy complications. Most current strategies use cytokines or antibodies to enhance NK-cell function, but none use ion channel modulators, which are widely used in clinical practice to treat hypertension, diabetes, epilepsy, and other conditions. Little is known about ion channels in NK cells. We show that Kcnj8, which codes for the Kir6.1 subunit of a certain type of ATP-sensitive potassium (K ATP ) channel, is highly expressed in murine splenic and uterine NK cells compared to other K + channels previously identified in NK cells. Kcnj8 expression is highest in the most mature subset of splenic NK cells (CD27 - CD11b + ) and in NKG2A + or Ly49C/I + educated uterine NK cells. Using patch clamping, we show that a subset of NK cells expresses a current sensitive to the Kir6.1 blocker PNU-37883A. Kcnj8 does not participate in NK cell degranulation in response to tumor cells in vitro or rejection of tumor cells in vivo . Transcriptomics show that genes previously implicated in NK cell development are amongst those differentially expressed in CD27 - CD11b + NK cells deficient of Kcnj8 . Indeed, we found that mice with NK-cell specific Kcnj8 gene ablation have fewer CD11b + CD27 - and KLRG-1 + NK cells in the bone barrow and spleen. These results show that the K ATP subunit Kir6.1 has a key role in NK-cell development.

The crystal structure of Acinetobacter baumannii bacterioferritin reveals a heteropolymer of bacterioferritin and ferritin subunits

Iron storage proteins, e.g., vertebrate ferritin, and the ferritin-like bacterioferritin (Bfr) and bacterial ferritin (Ftn), are spherical, hollow proteins that catalyze the oxidation of Fe2+ at binuclear iron ferroxidase centers (FOC) and store the Fe3+ in their interior, thus protecting cells from unwanted Fe3+/Fe2+ redox cycling and storing iron at concentrations far above the solubility of Fe3+. Vertebrate ferritins are heteropolymers of H and L subunits with only the H subunits having FOC. Bfr and Ftn were thought to coexist in bacteria as homopolymers, but recent evidence indicates these molecules are heteropolymers assembled from Bfr and Ftn subunits. Despite the heteropolymeric nature of vertebrate and bacterial ferritins, structures have been determined only for recombinant proteins constituted by a single subunit type. Herein we report the structure of Acinetobacter baumannii bacterioferritin, the first structural example of a heteropolymeric ferritin or ferritin-like molecule, assembled from completely overlapping Ftn homodimers harboring FOC and Bfr homodimers devoid of FOC but binding heme. The Ftn homodimers function by catalyzing the oxidation of Fe2+ to Fe3+, while the Bfr homodimers bind a cognate ferredoxin (Bfd) which reduces the stored Fe3+ by transferring electrons via the heme, enabling Fe2+ mobilization to the cytosol for incorporation in metabolism.

GABA(A) Receptor Subunit (γ2, δ, β1-3) Variants in Genetic Epilepsy: A Comprehensive Summary of 206 Clinical Cases.

Epilepsy is identified in individuals who experienced 2 or more unprovoked seizures occurring over 24 hours apart, which can have a profound impact on a person's neurobiological, cognitive, psychological, and social well-being. Epilepsy is considerably diverse, with classifications such as genetic epilepsy that result directly from a known or presumed genetic variant with the core symptoms of seizures. The GABAA receptor primarily functions as a heteropentamer, containing 3 of 8 subunit types: α, β, γ, δ, ε, π, θ, and ρ. In the adult brain, the GABAA receptor is the primary inhibitory component in neural networks. The involvement of GABAA receptors in the pathogenesis of epilepsy has been proposed. We extensively reviewed all relevant clinical data of previously published cases of GABAA receptor subunit γ2, δ, β1-3 variants included in PubMed up to February 2024, including the variant types, loci, postulated mechanisms, their relevant regions, first onset ages, and phenotypes. We summarized the postulated mechanisms of epileptic pathogenesis. We also divided the collected 206 cases of epilepsy into 4 epileptic phenotypes: genetic generalized epilepsies, focal epilepsy, developmental and epileptic encephalopathies, and epilepsy with fever sensibility. We showed that there were significant differences in the likelihood of the γ2, β2, and β3 subunit variants causing genetic generalized epilepsies, focal epilepsy, developmental and epileptic encephalopathies, and epilepsy with fever sensibility. Patients with the β3 subunit variant seemed related to an earlier first onset age. Our review supports that GABAA receptor subunit variants are a crucial area of epilepsy research and treatment exploration.

Behavioral and transcriptional effects of carnosine in the central ring ganglia of the pond snail Lymnaea stagnalis.

Carnosine is a naturally occurring endogenous dipeptide with well-recognized anti-inflammatory, antioxidant, and neuroprotective effects at the central nervous system level. To date, very few studies have been focused on the ability of carnosine to rescue and/or enhance memory. Here, we used a well-known invertebrate model system, the pond snail Lymnaea stagnalis, and a well-studied associative learning procedure, operant conditioning of aerial respiration, to investigate the ability of carnosine to enhance long-term memory (LTM) formation and reverse memory obstruction caused by an immune challenge (i.e., lipopolysaccharide [LPS] injection). Exposing snails to 1 mM carnosine for 1 h before training in addition to enhancing memory formation resulted in a significant upregulation of the expression levels of key neuroplasticity genes (i.e., glutamate ionotropic receptor N-methyl-d-aspartate [NMDA]-type subunit 1-LymGRIN1, and the transcription factor cAMP-response element-binding protein 1-LymCREB1) in snails' central ring ganglia. Moreover, pre-exposure to 1 mM carnosine before an LPS injection reversed the memory deficit brought about by inflammation, by preventing the upregulation of key targets for immune and stress response (i.e., Toll-like receptor 4-LymTLR4, molluscan defense molecule-LymMDM, heat shock protein 70-LymHSP70). Our data are thus consistent with the hypothesis that carnosine can have positive benefits on cognitive ability and be able to reverse memory aversive states induced by neuroinflammation.

LC-MS characterization of N/O-glycans of α- and β-subunits of chicken ovomucin separated by SDS-PAGE

As the main active glycoprotein of egg white, the biological functions of chicken ovomucin α- and β-subunit are closely related to the structure of glycans. However, the exact composition and structure of the subunit glycans are still unknown. We obtained highly pure chicken ovomucin α-subunit and β-subunit protein bands by the strategy combined with two-step isoelectric precipitation and SDS-PAGE gel electrophoresis. The ammonia-catalyzed one-pot procedure was then used to release and capture α-and β-subunit protein glycans with 1-phenyl- 3-Methyl-5-pyrazolone (PMP). The N/O-glycans of bis-PMP derivatives were purified and analyzed by LC-MS. More importantly, an effective dual modification was performed to accurately quantify neutral and sialylated O-glycans through methylamidation of sialic acid residues and simultaneously through carbonyl condensation reactions of reducing ends with PMP. We first showed that the α-subunit protein has only N-glycosylation modification, and the β-subunit only O-glycosylation, a total of 22 N-glycans and 20 O-glycans were identified in the α- and β-subunit, respectively. In addition, the complex N-glycan (47 %) and the sialylated O-glycan (77 %) are each major types of the above subunits. Such findings in this study provide a basis for studying the functional and biological activities of chicken ovomucin glycans.

Distinct neurodevelopmental and epileptic phenotypes associated with gain- and loss-of-function GABRB2 variants

Variants in GABRB2, encoding the β2 subunit of the γ-aminobutyric acid type A (GABAA) receptor, can result in a diverse range of conditions, ranging from febrile seizures to severe developmental and epileptic encephalopathies. However, the mechanisms underlying the risk of developing milder vs more severe forms of disorder remain unclear. In this study, we conducted a comprehensive genotype-phenotype correlation analysis in a cohort of individuals with GABRB2 variants. Genetic and electroclinical data of 42 individuals harbouring 26 different GABRB2 variants were collected and accompanied by electrophysiological analysis of the effects of the variants on receptor function. Electrophysiological assessments of α1β2γ2 receptors revealed that 25/26 variants caused dysfunction to core receptor properties such as GABA sensitivity. Of these, 17 resulted in gain-of-function (GOF) while eight yielded loss-of-function traits (LOF). Genotype-phenotype correlation analysis revealed that individuals harbouring GOF variants suffered from severe developmental delay/intellectual disability (DD/ID, 74%), movement disorders such as dystonia or dyskinesia (59%), microcephaly (50%) and high risk of early mortality (26%). Conversely, LOF variants were associated with milder disease manifestations. Individuals with these variants typically exhibited fever-triggered seizures (92%), milder degrees of DD/ID (85%), and maintained ambulatory function (85%). Notably, severe movement disorders or microcephaly were not reported in individuals with loss-of-function variants. The data reveals that genetic variants in GABRB2 can lead to both gain and loss-of-function, and this divergence is correlated with distinct disease manifestations. Utilising this information, we constructed a diagnostic flowchart that aids in predicting the pathogenicity of recently identified variants by considering clinical phenotypes. This work was funded by the Australian National Health & Medical Research Council, the Novo Nordisk Foundation and The Lundbeck Foundation.

The Structure of the LysR-type Transcriptional Regulator, CysB, Bound to the Inducer, N-acetylserine

In Escherichia coli and Salmonella typhimurium, cysteine biosynthesis requires the products of 20 or more cys genes co-ordinately regulated by CysB. Under conditions of sulphur limitation and in the presence of the inducer, N-acetylserine, CysB binds to cys promoters and activates the transcription of the downstream coding sequences. CysB is a homotetramer, comprising an N-terminal DNA binding domain (DBD) and a C-terminal effector binding domain (EBD). The crystal structure of a dimeric EBD fragment of CysB from Klebsiella aerogenes revealed a protein fold similar to that seen in Lac repressor but with a different symmetry in the dimer so that the mode of DNA binding was not apparent. To elucidate the subunit arrangement in the tetramer, we determined the crystal structure of intact CysB in complex with N-acetylserine. The tetramer has two subunit types that differ in the juxtaposition of their winged helix-turn-helix DNA binding domains with respect to the effector binding domain. In the assembly, the four EBDs form a core with the DNA binding domains arranged in pairs on the surface. N-acetylserine makes extensive polar interactions in an enclosed binding site, and its binding is accompanied by substantial conformational rearrangements of surrounding residues that are propagated to the protein surface where they appear to alter the arrangement of the DNA binding domains. The results are (i) discussed in relation to the extensive mutational data available for CysB and (ii) used to propose a structural mechanism of N-acetylserine induced CysB activation.

Transcriptomic analysis reveals novel hub genes associated with astrocyte autophagy in intracerebral hemorrhage.

Neuroinflammation serves as a critical local defense mechanism against secondary brain injury following intracerebral hemorrhage (ICH), and astrocytes play a prominent role in this process. In this study, we investigated astrocytic changes during the inflammatory state after ICH to identify new targets for improving the inflammatory response. We stimulated mouse astrocytes with lipopolysaccharide (LPS) in vitro and analyzed their transcriptomes via ribonucleic acid sequencing. We created an ICH model in living organisms by injecting autologous blood. RNA sequencing revealed that 2,717 genes were differentially expressed in the LPS group compared to those in the saline group, with notable enrichment of the autophagic pathway. By intersecting the 2,717 differentially expressed genes (DEGs) with autophagy-related genes, we identified 36 autophagy-related DEGs and seven hub genes. Previous studies and quantitative reverse transcription-polymerase chain reaction results confirmed the increased expression of phosphatidylinositol 3-kinase catalytic subunit type 3 (Pik3c3), AKT serine/threonine kinase 1 (Akt1), and unc-51 like autophagy activating kinase 2 (Ulk2) in astrocytes after ICH. Transcription factors and target miRNAs were identified for the final three DEGs, and 3-methyladenine and leupeptin were identified as potential therapeutic agents for ICH. Our findings suggest that astrocyte autophagy plays a critical role in ICH complexity, and that Pik3c3, Akt1, and Ulk2 may be potential therapeutic targets.

Dynamic regulation of CeA gene expression during acute and protracted abstinence from chronic binge drinking of male and female C57BL/6J mice

While there are numerous brain regions that have been shown to play a role in this AUD in humans and animal models, the central nucleus of the amygdala (CeA) has emerged as a critically important locus mediating binge alcohol consumption. In this study, we sought to understand how relative gene expression of key signaling molecules in the CeA changes during different periods of abstinence following bouts of binge drinking. To test this, we performed drinking in the dark (DID) on two separate cohorts of C57BL/6J mice and collected CeA brain tissue at 1 day (acute) and 7 days (protracted) abstinence after DID. We used qRTPCR to evaluate relative gene expression changes of 25 distinct genes of interest related to G protein-coupled receptors (GPCRs), neuropeptides, ion channel subunits, and enzymes that have been previously implicated in AUD. Our findings show that during acute abstinence CeA punches collected from female mice had upregulated relative mRNA expression of the gamma-aminobutyric acid receptor subunit alpha 2 (Gabra2), and the peptidase, angiotensinase c (Prcp). CeA punches from male mice at the same time point in abstinence had upregulated relative mRNA encoding for neuropeptide-related molecules, neuropeptide Y (Npy) and somatostatin (Sst), as well as the neuropeptide Y receptor Y2 (Npyr2), but downregulated Glutamate ionotropic receptor NMDA type subunit 1 (Grin1). After protracted abstinence, CeA punches collected from female mice had increased mRNA expression of corticotropin releasing hormone (Crh) and Npy. CeA punches collected from male mice at the same timepoint had upregulated relative mRNA expression of Npy2r, Npy, and Sst. Our findings support that there are differences in how the CeA of male and female mice respond to binge-alcohol exposure, highlighting the need to understand the implications of such differences in the context of AUD and binge drinking behavior.

E3 ligase DECREASED GRAIN SIZE 1 promotes degradation of a G-protein subunit and positively regulates grain size in rice.

Grain size is one of the most important traits determining crop yield. However, the mechanism controlling grain size remains unclear. Here, we confirmed the E3 ligase activity of DECREASED GRAIN SIZE 1 (DGS1) in positive regulation of grain size in rice (Oryza sativa) suggested in a previous study. Rice G-protein subunit gamma 2 (RGG2), which negatively regulates grain size, was identified as an interacting protein of DGS1. Biochemical analysis suggested that DGS1 specifically interacts with canonical Gγ subunits (rice G-protein subunit gamma 1 [RGG1] and rice G-protein subunit gamma 2 [RGG2]) rather than non-canonical Gγ subunits (DENSE AND ERECT PANICLE 1 [DEP1], rice G-protein gamma subunit type C 2 [GCC2], GRAIN SIZE 3 [GS3]). We also identified the necessary domains for interaction between DGS1 and RGG2. As an E3 ligase, DGS1 ubiquitinated and degraded RGG2 via a proteasome pathway in several experiments. DGS1 also ubiquitinated RGG2 by its K140, K145 and S147 residues. Thus, this work identified a substrate of the E3 ligase DGS1 and elucidated the post transcriptional regulatory mechanism of the G-protein signalling pathway in the control of grain size.

Characterization of the zebrafish gabra1sa43718/sa43718 germline loss of function allele confirms a function for Gabra1 in motility and nervous system development

Mutation of the GABRA1 gene is associated with neurodevelopmental defects and epilepsy. GABRA1 encodes for the α1 subunit of the γ-aminobutyric acid type A receptor (GABAAR), which regulates the fast inhibitory impulses of the nervous system. Multiple model systems have been developed to understand the function of GABRA1, but these models have produced complex and, at times, incongruent data. Thus, additional model systems are required to validate and substantiate previous results. We sought to provide initial phenotypic analysis of a novel germline mutant allele. Our analysis provides a solid foundation for the future use of this allele to characterize gabra1 functionally and pharmacologically using zebrafish. We investigated the behavioral swim patterns associated with a nonsense mutation of the zebrafish gabra1 (sa43718 allele) gene. The sa43718 allele causes a decrease in gabra1 mRNA expression, which is associated with light induced hypermotility, one phenotype previously associated with seizure like behavior in zebrafish. Mutation of gabra1 was accompanied by decreased mRNA expression of gabra2, gabra3, and gabra5, indicating a reduction in the expression of additional α sub-units of the GABAAR. Although multiple sub-units were decreased, larvae continued to respond to pentylenetetrazole (PTZ), indicating that a residual GABAAR exists in the sa43718 allele. Proteomics analysis demonstrated that mutation of gabra1 is associated with abnormal expression of proteins that regulate synaptic vesicle fusion, vesicle transport, synapse development, and mitochondrial protein complexes. These data support previous studies performed in a zebrafish nonsense allele created by CRISPR/Cas9 and validate that loss of function mutations in the gabra1 gene result in seizure-like phenotypes with abnormal development of the GABA synapse. Our results add to the existing body of knowledge as to the function of GABRA1 during development and validate that zebrafish can be used to provide complete functional characterization of the gene.