Α1 Subunit Research Articles

Effect of Perinatal Hypoxia (Asphixia) on the Distribution of the α1 GABA<sub>A</sub>-Receptor Subunit in the Neocortex of Newborn Rats

The aim of this work was to study the distribution of the α1 GABAA-receptor subunit in the neocortical layers of rats in the neonatal period after exposure to hypoxia. The effect of hypoxia on the brain of newborn rats was carried out on the 2nd neonatal day for 1 h at an oxygen content in the respiratory mixture of 7.8%. An immunohistochemical reaction was used to detect the α1 GABAA-receptor subunit. The quantitative protein content was estimated from the density of immunostaining of the reaction product in the cytoplasm and processes of neurons. The somatosensory area of the neocortex was studied on the 5th and 10th neonatal days (P5, P10). It has been established that in the neocortex there is a significant population of young neurons containing the α1 subunit, which is part of the GABAA-receptor in the early stages of the neonatal period. By the end of the neonatal period in control animals, the staining density of the product of reaction to the detection of GABAAα1 in the layers of the neocortex increases significantly. Exposure to perinatal hypoxia causes a reduction in the number of neurons containing the α1 GABAA-receptor subunit and a significant decrease in the density of immune staining in all layers of the neocortex.

4D-DIA quantitative proteomics revealed the core mechanism of diabetic retinopathy after berberine treatment

ObjectiveTo reveal the core mechanism of berberine (BBR) in the treatment of diabetic retinopathy (DR), by using Four-dimensional independent data acquisition (4D-DIA) proteomics combined bioinformatics analysis with experimental validation. Methods: DR injury model was established by injecting streptozotocin intraperitoneally. At 8 weeks after BBR administration, optical coherence tomography (OTC) photos and Hematoxylin-eosin staining from retina in each group were performed, then the retina was collected for 4D-DIA quantitative proteomics detection. Moreover, difference protein analysis, Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, protein-protein interaction (PPI) network, as well as molecular docking was performed, respectively. In the part of experiment, Western blot (WB) and immunofluorescent staining was used to confirm the change and distribution of carbonic anhydrase 1 (CA1), one of the most important molecules from quantitative PCR detection. Lastly, RNA knockdown was used to determine the crucial role of CA1 in retinal pigment epithelial cells (RPEs) administrated with berberine. ResultsOCT detection showed that the outer nucleus, inner layer and outer accessory layer of RPEs were thinned in DR group, compared with in sham one, while they were thickened after berberine administration, when compared with in DR group. 10 proteins were screened out by using proteomic analysis and Venny cross plot, in which, denn domain containing 1A (DENND1A) and UTP6 small subunit processome component (UTP6) was down-regulated, while ATPase copper transporting alpha (ATP7A), periplakin (PPL), osteoglycin (OGN), nse1 Homolog (NSMCE1), membrane metalloendopeptidase (MME), lim domain only 4 (LMO4), CA1 and fibronectin 1 (FN1) was up-regulated in DR group, and the BBR treatment can effectively reverse their expressions. PPI results showed that 10 proteins shared interactions with each other, but only ATP7A, FN1 and OGN exhibited directly associated with each other. Moreover, we enlarged the linked relation up to 15 genes in network, based on 10 proteins found from proteomics detection, so as to perform deep GO and KEGG analysis. As a result, the most important biological process is involving rRNA processing; the most important cell component is small subunit processor; the most important molecular function is Phospholipid binding; the KEGG pathway was Ribosome biogenesis in eukaryotes. Moreover, molecular docking showed that LMO4, ATP7A, PPL, NSMCE1, MME, CA1 could form a stable molecular binding pattern with BBR. Of these, the mRNA expression of CA1, PPL and ATP7A and the protein level of CA1 was increased in DR, and decreased in BBR group. Lastly, CA1 RNA knockdown confirmed the crucial role of CA1 in RPE administered with BBR. ConclusionThe present findings confirmed the role of BBR in DR treatment and explained associated molecular network mechanism, in which, CA1 could be considered as a crucial candidate in the protection of RPEs with berberine treatment.

ATP1A1-linked diseases require a malfunctioning protein product from one allele

Heterozygous germline variants in ATP1A1, the gene encoding the α1 subunit of the Na+/K+-ATPase (NKA), have been linked to diseases including primary hyperaldosteronism and the peripheral neuropathy Charcot-Marie-Tooth disease (CMT). ATP1A1 variants that cause CMT induce loss-of-function of NKA. This heterodimeric (αβ) enzyme hydrolyzes ATP to establish transmembrane electrochemical gradients of Na+ and K+ that are essential for electrical signaling and cell survival. Of the 4 catalytic subunit isoforms, α1 is ubiquitously expressed and is the predominant paralog in peripheral axons. Human population sequencing datasets indicate strong negative selection against both missense and protein-null ATP1A1 variants. To test whether haploinsufficiency generated by heterozygous protein-null alleles are sufficient to cause disease, we tested the neuromuscular characteristics of heterozygous Atp1a1+/− knockout mice and their wildtype littermates, while also evaluating if exercise increased CMT penetrance. We found that Atp1a1+/− mice were phenotypically normal up to 18 months of age. Consistent with the observations in mice, we report clinical phenotyping of a healthy adult human who lacks any clinical features of known ATP1A1-related diseases despite carrying a plasma-membrane protein-null early truncation variant, p.Y148*. Taken together, these results suggest that a malfunctioning gene product is required for disease induction by ATP1A1 variants and that if any pathology is associated with protein-null variants, they may display low penetrance or high age of onset.

Low-dose benzo[a]pyrene exposure induces hepatic lipid deposition through LCMT1/PP2Ac-mediated autophagy inhibition.

Non-alcoholic fatty liver disease (NAFLD) is a progressive disorder of liver metabolism and has become the most common chronic liver disease worldwide. Benzo[a]pyrene (BaP) is recognized as a potent carcinogen, but the effect of low-dose BaP on the development of NAFLD has not been well-studied, and its molecular mechanism is still unknown. In this study, we demonstrated that low-dose BaP induced hepatic steatosis in a mouse model with a notable increase in hepatic lipid content. Interestingly, mRNA expression of genes related to fatty acids uptake or synthesis was not significantly altered after BaP exposure. Instead, we found that low-dose BaP promoted lipid deposition in primary mouse hepatocytes by inhibiting autophagy, which was regulated through Leucine carboxyl methyltransferase-1 (LCMT1) mediated Protein Phosphatases 2A subunit C (PP2Ac) methylation. The role of LCMT1 in BaP-induced steatosis was further validated in a liver-specific lcmt1 knockout (L-LCMT1 KO) mouse model. In this study, we provided evidence to support a novel mechanism by which BaP induces the development of hepatic steatosis through PP2Ac mediated autophagy inhibition. These findings provided new insight into the pathogenesis of NAFLD induced by environmental exposure to low-dose BaP.

Inversed Effects of Nav1.2 Deficiency at Medial Prefrontal Cortex and Ventral Tegmental Area for Prepulse Inhibition in Acoustic Startle Response.

Numerous pathogenic variants of SCN2A gene, encoding voltage-gated sodium channel α2 subunit Nav1.2 protein, have been identified in a wide spectrum of neuropsychiatric disorders including schizophrenia. However, pathological mechanisms for the schizophrenia-relevant behavioral abnormalities caused by the variants remain poorly understood. Here in this study, we characterized mouse lines with selective Scn2a deletion at schizophrenia-related brain regions, medial prefrontal cortex (mPFC) or ventral tegmental area (VTA), obtained by injecting adeno-associated viruses (AAV) expressing Cre recombinase into homozygous Scn2a-floxed (Scn2afl/fl) mice, in which expression of the Scn2a was locally deleted in the presence of Cre recombinase. The mice lacking Scn2a in the mPFC exhibited a tendency for a reduction in prepulse inhibition (PPI) in acoustic startle response. Conversely, the mice lacking Scn2a in the VTA showed a significant increase in PPI. We also found that the mice lacking Scn2a in the mPFC displayed increased sociability, decreased locomotor activity, and increased anxiety-like behavior, while the mice lacking Scn2a in the VTA did not show any other abnormalities in these parameters except for vertical activity which is one of locomotor activities. These results suggest that Scn2a-deficiencies in mPFC and VTA are inversely relevant for the schizophrenic phenotypes in patients with SCN2A variants.

Promising Antigen-specific Immunotherapy for the Treatment of Myasthenia Gravis

Myasthenia gravis (MG) is a T cell-dependent, antibody-mediated, autoimmune disorder with well-established antigenic targets at the neuromuscular junction. MG autoantibodies mainly target the nicotinic acetylcholine receptor (AChR) and especially epitopes located in the extracellular domain of the α1 subunit (α1-ECD). Today, most therapeutic regimens for MG are non-specific and not curative, requiring chronic treatments that are associated with significant side effects. We aim to develop an antigen-specific therapeutic approach, based on reestablishing tolerance towards the AChR, the dominant autoantigen in MG. To this end, we used a soluble mutated form of the human α1-ECD, which incorporates a major fraction of MG autoreactive T cell epitopes and examined the therapeutic efficiency of intravenous administration in a rat experimental autoimmune MG model. We found that repeated intravenous administration of α1-ECD for up to 12 days led to a robust amelioration of disease symptoms in a dose and time-dependent manner. The observed therapeutic effect of α1-ECD was significantly better than the effect of two current mainstay drugs for MG treatment. There were no signs of toxicity in α1-ECD-treated animals and further studies are underway to fully elucidate the immunological mechanism underlying the treatment effect. Taken together, our preclinical data strongly suggest that intravenous administration of α1-ECD may represent an efficacious and safe strategy to treat MG and thus α1-ECD represents a new drug candidate for clinical application in MG.

A novel binding site between the voltage-dependent calcium channel CaV1.2 subunit and CaVβ2 subunit discovered using a new analysis method for protein–protein interactions

We developed a new method to analyze protein–protein interactions using a dual-inducible prokaryotic expression system. To evaluate protein–protein binding, a chimeric fusion toxin gene was constructed using a DNase-treated short DNA fragment (epitope library) and CcdB, which encodes a DNA topoisomerase II toxin. Protein–protein interactions would affect toxin activity, resulting in colony formation. Using this novel system, we found a new binding site in the voltage-dependent calcium channel α1 subunit (CaV1.2) for the voltage-dependent calcium channel β2 subunit. Prokaryotic expression screening of the β2 subunit using an epitope library of CaV1.2 resulted in two overlapping clones of the C-terminal sequence of CaV1.2. In vitro overlay and immunoprecipitation analyses revealed preferential binding of the C-terminal sequences of CaV1.2 and β2.

Silencing of ATP1A1 attenuates cell membrane disruption by nanosecond electric pulses

This study explored the role of the Na/K-ATPase (NKA) in membrane permeabilization induced by nanosecond electric pulses. Using CRISPR/Cas9 and shRNA, we silenced the ATP1A1 gene, which encodes α1 NKA subunit in U937 human monocytes. Silencing reduced the rate and the cumulative uptake of YoPro-1 dye after electroporation by 300-ns, 7–10 kV/cm pulses, while ouabain, a specific NKA inhibitor, enhanced YoPro-1 entry. We conclude that the α1 subunit supports the electropermeabilized membrane state, by forming or stabilizing electropores or by hindering repair mechanisms, and this role is independent of NKA's ion pump function.

CBD enhances the cognitive score of adolescent rats prenatally exposed to THC and fine-tunes relevant effectors of hippocampal plasticity.

Introduction: An altered neurodevelopmental trajectory associated with prenatal exposure to ∆-9-tetrahydrocannabinol (THC) leads to aberrant cognitive processing through a perturbation in the effectors of hippocampal plasticity in the juvenile offspring. As adolescence presents a unique window of opportunity for "brain reprogramming", we aimed at assessing the role of the non-psychoactive phytocannabinoid cannabidiol (CBD) as a rescue strategy to temper prenatal THC-induced harm. Methods: To this aim, Wistar rats prenatally exposed to THC (2mg/kg s.c.) or vehicle (gestational days 5-20) were tested for specific indexes of spatial and configural memory in the reinforcement-motivated Can test and in the aversion-driven Barnes maze test during adolescence. Markers of hippocampal excitatory plasticity and endocannabinoid signaling-NMDAR subunits NR1 and 2A-, mGluR5-, and their respective scaffold proteins PSD95- and Homer 1-; CB1R- and the neuromodulatory protein HINT1 mRNA levels were evaluated. CBD (40mg/kg i.p.) was administered to the adolescent offspring before the cognitive tasks. Results: The present results show that prenatal THC impairs hippocampal memory functions and the underlying synaptic plasticity; CBD is able to mitigate cognitive impairment in both reinforcement- and aversion-related tasks and the neuroadaptation of hippocampal excitatory synapses and CB1R-related signaling. Discussion: While this research shows CBD potential in dampening prenatal THC-induced consequences, we point out the urgency to curb cannabis use during pregnancy in order to avoid detrimental bio-behavioral outcomes in the offspring.

Functional Analysis and Clinical Importance of ATP1A1 in Colon Cancer.

Na+/K+-ATPase α1 subunit (ATP1A1) exhibits aberrant expression in various types of cancer. Moreover, its levels in specific tissues are associated with the development of cancer. Nevertheless, the mechanism and signaling pathways underlying the effects of ATP1A1 in colon cancer (CC) have not been elucidated, and its prognostic impact remains unknown. Knockdown of ATP1A1 expression was performed in human CC cell lines HT29 and Caco2 using small interfering RNA. The roles of ATP1A1 in various biological processes of cells (i.e., proliferation, cell cycle, apoptosis, migration, and invasion) were assessed. Microarray analysis was utilized for gene expression profiling. Samples obtained from 200 patients with CC who underwent curative colectomy were analyzed through immunohistochemistry. ATP1A1 knockdown suppressed cell proliferation, migration, and invasion and induced apoptosis. The results of the microarray analysis revealed that the upregulated or downregulated gene expression in ATP1A1-depleted cells was related to the extracellular signal-regulated kinase 5 (ERK5) signaling pathway [epidermal growth factor receptor (EGFR), mitogen-activated protein kinase kinase 5 (MAP2K5), mitogen-activated protein kinase 7 (MAPK7), FOS, MYC, and BCL2 associated agonist of cell death (BAD)]. Immunohistochemical analysis demonstrated a correlation between ATP1A1 expression and pathological T stage (p = 0.0054), and multivariate analysis identified high ATP1A1 expression as an independent predictor of poor recurrence-free survival in patients with CC (p = 0.0040, hazard ratio: 2.807, 95% confidence interval 1.376-6.196). ATP1A1 regulates tumor progression through the ERK5 signaling pathway. High ATP1A1 expression is associated with poor long-term outcomes in patients with CC.

3', 4'-dihydroxyflavone ameliorates paclitaxel model of peripheral neuropathy in mice by modulating KATP channel, adenosine (A3) and GABAA (α2 subunit) receptors.

Paclitaxel is a widely used cancer chemotherapeutic agent for many solid tumors; but peripheral neuropathy is a major limitation for its clinical use. Studies have demonstrated the usefulness of flavone derivatives in chemotherapy induced peripheral neuropathy. The present study evaluates the anti-neuropathic effect of 3', 4'-dihydroxyflavone on paclitaxel-induced peripheral neuropathy and the underlying mechanisms. Paclitaxel was administered to mice in a single dose of 10 mg/kg, i.p.The neuropathic behavioural parameters such as mechanical allodynia, cold allodynia and thermal hyperalgesia were assessed 24 h later. The test compound 3', 4'-dihydroxyflavone (50,100 or 200 mg/kg,s.c) was administered 30 min prior to the assessment of behavioral parameters. The possible mechanisms involving KATP channels, adenosine and GABAA receptors were explored by employing suitable interacting drugs. Molecular docking studies to predict the binding interactions of 3', 4'-dihydroxyflavone at the above targets were also carried out. The test compound 3', 4'-dihydroxyflavoneexhibited a significant reduction in paw withdrawal response score in both mechanical and cold allodynia and also increased the tail flick response time in thermal hyperalgesia due to paclitaxel-induced neuropathy. The anti-neuropathic effect of 3', 4'-dihydroxyflavonewas significantly reversed by pre-treatment with glibenclamide, caffeine or bicuculline revealing the involvement of KATP channels, adenosine and GABAA receptors respectively. Furthermore, the molecular docking studies indicated a favourable binding affinity and good H-bond interaction of 3', 4'-dihydroxyflavone at these targets. The findings of the present study suggests that, 3', 4'-dihydroxyflavone has anti-neuropathic effect against paclitaxel-induced peripheral neuropathy through mechanisms that involve KATP channels, adenosine (A3) and GABAA (α2 subunit) receptors.

Diazepam-Induced Down-Regulation of the GABAA receptor α1 Subunit, as mediated by the activation of L-Type Voltage-Gated calcium Channel/Ca2+/Protein kinase a signaling cascade

Benzodiazepines are among the most prescribed drug class worldwide to treat disorders such as anxiety, insomnia, muscle spasticity, and convulsive disorders, and to induce presurgical sedation. Although benzodiazepines exhibit a high therapeutic index and low toxicity in short-term treatments, prolonged administration induces tolerance to most of their therapeutic actions. The mechanism of this tolerance remains unclear. The central actions of benzodiazepines are mediated by binding to GABAA receptors, which mediate most fast inhibitory transmission in the brain. The majority of GABAA receptors are composed of two α-(1–6), two β-(1–3) and one γ-subunits (1–3). In a previous report, we demonstrated that the prolonged exposure of cerebrocortical neurons to diazepam produces a transcriptional repression of the GABAA receptor α1 subunit gene via a mechanism dependent on the activation of L-type voltage-gated calcium channels (L-VGCCs). The results reported here confirm that the diazepam-induced downregulation of the α1 subunit is contingent upon calcium influx from extracellular space. In addition, this regulatory mechanism involves the activation of protein kinase A (PKA) and is accompanied by the activation of two transcription factors, the cAMP-response element-binding protein (CREB) and the inducible cAMP early repressor (ICER). Together, our results suggest that diazepam s activation of an L-VGCC/Ca2+/PKA/CREB-ICER signaling pathway is responsible for the regulation of GABAA receptors. This elucidation of the intracellular signaling cascade activated by a prolonged benzodiazepine exposure, itself potentially involved in the development of tolerance, may contribute to locating molecular targets for future therapeutic interventions.

Active Zone Trafficking of CaV2/UNC-2 Channels Is Independent of β/CCB-1 and α2δ/UNC-36 Subunits.

The CaV2 voltage-gated calcium channel is the major conduit of calcium ions necessary for neurotransmitter release at presynaptic active zones (AZs). The CaV2 channel is a multimeric complex that consists of a pore-forming α1 subunit and two auxiliary β and α2δ subunits. Although auxiliary subunits are critical for channel function, whether they are required for α1 trafficking is unresolved. Using endogenously fluorescent protein-tagged CaV2 channel subunits in Caenorhabditis elegans, we show that UNC-2/α1 localizes to AZs even in the absence of CCB-1/β or UNC-36/α2δ, albeit at low levels. When UNC-2 is manipulated to be trapped in the endoplasmic reticulum (ER), CCB-1 and UNC-36 fail to colocalize with UNC-2 in the ER, indicating that they do not coassemble with UNC-2 in the ER. Moreover, blocking ER-associated degradation does not further increase presynaptic UNC-2 channels in ccb-1 or unc-36 mutants, indicating that UNC-2 levels are not regulated in the ER. An unc-2 mutant lacking C-terminal AZ protein interaction sites with intact auxiliary subunit binding sites displays persistent presynaptic UNC-2 localization and a prominent increase of UNC-2 channels in nonsynaptic axonal regions, underscoring a protective role of auxiliary subunits against UNC-2 degradation. In the absence of UNC-2, presynaptic CCB-1 and UNC-36 are profoundly diminished to barely detectable levels, indicating that UNC-2 is required for the presynaptic localization of CCB-1 and UNC-36. Together, our findings demonstrate that although the pore-forming subunit does not require auxiliary subunits for its trafficking and transport to AZs, it recruits auxiliary subunits to stabilize and expand calcium channel signalosomes.SIGNIFICANCE STATEMENT Synaptic transmission in the neuron hinges on the coupling of synaptic vesicle exocytosis with calcium influx. This calcium influx is mediated by CaV2 voltage-gated calcium channels. These channels consist of one pore-forming α1 subunit and two auxiliary β and α2δ subunits. The auxiliary subunits enhance channel function and regulate the overall level of channels at presynaptic terminals. However, it is not settled how these auxiliary subunits regulate the overall channel level. Our study in C. elegans finds that although the auxiliary subunits do not coassemble with α1 and aid trafficking, they are recruited to α1 and stabilize the channel complex at presynaptic terminals. Our study suggests that drugs that target the auxiliary subunits can directly destabilize and have an impact on CaV2 channels.

Improved enzymatic labeling of fluorescent in situ hybridization probes applied to the visualization of retained introns in cells.

Fluorescence in situ hybridization (FISH) is a widely used tool for quantifying gene expression and determining the location of RNA molecules in cells. We present an improved method for FISH probe production that yields high-purity probes with a wide range of fluorophores using standard laboratory equipment at low cost. The method modifies an earlier protocol that uses terminal deoxynucleotidyl transferase to add fluorescently labeled nucleotides to synthetic deoxyoligonucleotides. In our protocol, amino-11-ddUTP is joined to an oligonucleotide pool prior to its conjugation to a fluorescent dye, thereby generating pools of probes ready for a variety of modifications. This order of reaction steps allows for high labeling efficiencies regardless of the GC content or terminal base of the oligonucleotides. The degree of labeling (DOL) for spectrally distinct fluorophores (Quasar, ATTO, and Alexa dyes) was mostly >90%, comparable with commercial probes. The ease and low cost of production allowed the generation of probe sets targeting a wide variety of RNA molecules. Using these probes, FISH assays in C2C12 cells showed the expected subcellular localization of mRNAs and pre-mRNAs for Polr2a (RNA polymerase II subunit 2a) and Gapdh, and of the long noncoding RNAs Malat1 and Neat1 Developing FISH probe sets for several transcripts containing retained introns, we found that retained introns in the Gabbr1 and Noc2l transcripts are present in subnuclear foci separate from their sites of synthesis and partially coincident with nuclear speckles. This labeling protocol should have many applications in RNA biology.

DR region of NKAα1 is a target to ameliorate hepatic lipid metabolism disturbance in obese mice

BackgroundNa+/K+-ATPase (NKA), an ion pumping enzyme ubiquitously expressed in various cells, is critically involved in cellular ion homeostasis and signal transduction. However, the role of NKA in hepatic lipid homeostasis has yet to be fully characterized. MethodsThe activity of NKA and NKAα1 expression were determined in steatotic cells, mice and patients. The roles of NKAα1 in hepatosteatosis were detected using hepatocyte knockout or specific overexpression of NKAα1 in mice. ResultsHerein, we demonstrated that the expression and activity of α1 subunit of NKA (NKAα1) were lowered in the livers of nonalcoholic fatty liver disease (NAFLD) patients, high-fat diet (HFD)-induced obese mice, and genetically obese (ob/ob, db/db) mice, as well as oleic acid-induced hepatocytes. Hepatic deficiency of NKAα1 exacerbated, while adeno-associated virus-mediated liver specific overexpression of NKAα1 alleviated hepatic steatosis through regulation of fatty acid oxidation (FAO) and lipogenesis. Mechanistically, we revealed that NKAα1 upregulated sirtuin 1 (SIRT1) via interacting with ubiquitin specific peptidase 22 (USP22), a deubiquitinating enzyme for the stabilization and deubiquitination of SIRT1, thus activating the downstream autophagy signaling. Blockade of the SIRT1/autophagy signaling pathway eliminated the protective effects of NKAα1 against lipid deposition in hepatocytes. Importantly, we found that an antibody against the DR region (897DVEDSYGQQWTYEQR911) of NKAα1 subunit (DR-Ab) ameliorated hepatic steatosis through maintaining the membrane density of NKAα1 and inducing its activation. ConclusionsCollectively, this study renews the functions of NKAα1 in liver lipid metabolism and provides a new clue for gene therapy or antibody treatment of hepatic lipid metabolism disturbance by targeting NKAα1.

Loss of AMPKα2 promotes melanoma tumor growth and brain metastasis

AMP-activated protein kinase (AMPK) is a critical cellular energy sensor at the interface of metabolism and cancer. However, the role of AMPK in carcinogenesis remains unclear. Here, through analysis of the TCGA melanoma dataset, we found that PRKAA2 gene that encodes the α2 subunit of AMPK is mutated in ∼9% of cutaneous melanomas, and these mutations tend to co-occur with NF1 mutations. Knockout of AMPKα2 promoted anchorage-independent growth of NF1-mutant melanoma cells, whereas ectopic expression of AMPKα2 inhibited their growth in soft agar assays. Moreover, loss of AMPKα2 accelerated tumor growth of NF1-mutant melanoma and enhanced their brain metastasis in immune-deficient mice. Our findings support that AMPKα2 serves as a tumor suppressor in NF1-mutant melanoma and suggest that AMPK could be a therapeutic target for treating melanoma brain metastasis.

Two novel homozygous variants of ATP6V0A2 and ALDH18A1 lead to autosomal recessive cutis laxa type 2 and 3 in two Pakistani families.

Autosomal recessive cutis laxa type 2A (ARCL2A; OMIM: 219200) is characterized by neurovegetative, developmental and progeroid elastic skin anomalies. It is caused by biallelic variation in ATPase, H+ transporting V0 subunit A2 (ATP6V0A2; OMIM: 611716) located on chromosome 12q24.31. Autosomal recessive cutis laxa type 3A (ARCL3A; OMIM: 219150) is another subclinical type characterized by short stature, ophthalmological abnormalities and a progeria-like appearance. The ARCL3A is caused by loss of function alterations in the aldehyde dehydrogenase 18 family member A1 (ALDH18A1; OMIM: 138250) gene located at chromosome 10q24.1. Whole-exome sequencing (WES), and Sanger sequencing were performed for molecular diagnosis. 3D protein modeling was performed to investigate the deleterious effect of the variant on protein structure. In this study, clinical and molecular diagnosis were performed for two families, ED-01 and DWF-41, which displayed hallmark features of ARCL2A and ARCL3A, respectively. Three affected individuals in the ED-01 family (IV-4, IV-5 and V-3) displayed sagging loose skin, down-slanting palpebral fissures, excessive wrinkles on the abdomen, hands and feet, and prominent veins on the trunk. Meanwhile the affected individuals in the DWF-41 family (V-2 and V-3) had progeroid skin, short stature, dysmorphology, low muscle tone, epilepsy, lordosis, scoliosis, delayed puberty and internal genitalia. WES in the index patient (ED-01: IV-4) identified a novel homozygous deletion (NM_012463.3: c.1977_1980del; p.[Val660LeufsTer23]) in exon 16 of the ATP6V0A2 while in DWF-41 a novel homozygous missense variant (NM_001323413.1:c.1867G>A; p.[Asp623Asn]) in exon 15 of the ALDH18A1 was identified. Sanger validation in all available family members confirmed the autosomal recessive modes of inheritances in each family. Three dimensional in-silico protein modeling suggested deleterious impact of the identified variants. Furthermore, these variants were assigned class 1 or "pathogenic" as per guidelines of American College of Medical Genetics 2015. Screening of ethnically matched healthy controls (n= 200 chromosomes), excluded the presence of these variations in general population. To the best of our knowledge, this is the first report of ATP6V0A2 and ALDH18A1 variations in the Pakhtun ethnicity of Pakistani population. The study confirms that WES can be used as a first-line diagnostic test in patients with cutis laxa, and provides basis for population screening and premarital testing to reduce the diseases burden in future generations.

Glycine receptors in GtoPdb v.2023.1

The inhibitory glycine receptor (nomenclature as agreed by the NC-IUPHAR Subcommittee on Glycine Receptors) is a member of the Cys-loop superfamily of transmitter-gated ion channels that includes the GABAA, nicotinic acetylcholine and 5-HT3 receptors and Zn2+- activated channels. The glycine receptor is expressed either as a homo-pentamer of α subunits, or a complex of 4α and 1β subunits [131], that contains an intrinsic anion channel. Four differentially expressed isoforms of the α-subunit (α1-α4) and one variant of the β-subunit (β1, GLRB, P48167) have been identified by genomic and cDNA cloning. Further diversity originates from alternative splicing of the primary gene transcripts for α1 (α1INS and α1del), α2 (α2A and α2B), α3 (α3S and α3L) and β (βΔ7) subunits and by mRNA editing of the α2 and α3 subunit [20, 84, 94]. Both α2 splicing and α3 mRNA editing can produce subunits (i.e., α2B and α3P185L) with enhanced agonist sensitivity. Predominantly, the adult form of the receptor contains α1 (or α3) and β subunits whereas the immature form is mostly composed of only α2 subunits [79]. The α4 subunit is a pseudogene in humans [66]. High resolution molecular structures are available for α1 homomeric, α3 homomeric, and αβ hteromeric receptors in a variety of ligand-induced conformations [19, 129, 19, 48, 49, 50]. As in other Cys-loop receptors, the orthosteric binding site for agonists and the competitive antagonist strychnine is formed at the interfaces between the subunits’ extracellular domains. Inclusion of the β-subunit in the pentameric glycine receptor contributes to agonist binding, reduces single channel conductance and alters pharmacology. The β-subunit also anchors the receptor, via an amphipathic sequence within the large intracellular loop region, to gephyrin. This a cytoskeletal attachment protein that binds to a number of subsynaptic proteins involved in cytoskeletal structure and thus clusters and anchors hetero-oligomeric receptors to the synapse [55, 89]. G protein βγ subunits enhance the open state probability of native and recombinant glycine receptors by association with domains within the large intracellular loop [125, 124]. Intracellular chloride concentration modulates the kinetics of native and recombinant glycine receptors [97]. Intracellular Ca2+ appears to increase native and recombinant glycine receptor affinity, prolonging channel open events, by a mechanism that does not involve phosphorylation [26]. Extracellular Zn2+ potentiates GlyR function at nanomolar concentrations [87]. and causes inhibition at higher micromolar concentrations (17).

GABA-A Receptor Meningoencephalitis presenting with New Onset Refractory Status Epilepticus and Reversible Vasculopathy (P4-5.002)

<h3>Objective:</h3> Discuss current clinical and neuroimaging phenotypes associated with GABA-A receptor encephalitis as applied to the case of a 14-year old female with a two-month history of behavior change and subsequent development of new onset refractory status epilpeticus and reversible vasculopathy. <h3>Background:</h3> Anti-Gamma Amino Butyric Acid-A (GABA-A) Receptor Encephalitis is an antibody mediated encephalitis which manifests with neurocognitive dysfunction, pharmacoresistant seizures, movement disorders, dysautonomia, and multifocal T2 FLAIR lesions in the cortex and subcortex without mass effect or enhancement. Not all patients fulfill these characteristics, creating challenges in early identification and treatment. <h3>Design/Methods:</h3> n/a <h3>Results:</h3> In this case we will discuss the current clinical and neuroimaging phenotypes associated with GABA-A receptor encephalitis cited in the literature and challenge their application to the case of a 14-year old female with a two-month history of behavior change and weight loss who was found to have serum and CSF positive anti-GABA-A receptor α1 subunit encephalitis. MRI showed persistent multifocal cortical/subcortical T2 changes during evaluation. Clinical course progressed from her initial behavioral changes to development of dysautonomia, new onset refractory status epilepticus (NORSE), and reversible vasculopathy. NORSE did not resolve until immunotherapy was escalated to apharesis and rituximab. Patient clinically improved and started cyclophosphamide for maintenance immunotherapy. <h3>Conclusions:</h3> GABA-A Receptor Encephalitis clinical features demonstrate progressive behavioral changes, dysautonomia, and new onset refractory status epilepticus. Radiographic features include persistent multifocal cortical/subcortical T2 changes. This case reinforces the previously described clinical and radiographic phenotypes of GABA-A receptor encephalitis, as well as the role of timely escalation of immunotherapy treatment. Further investigation is needed to observe the impact of primary immunodeficiency disorders and antibody mediated encephalitis disease. <b>Disclosure:</b> Dr. Garcia has nothing to disclose. Dr. Crowson has nothing to disclose. Dr. Angappan has nothing to disclose. Dr. Chen has received research support from OHSU Foundation. Dr. Yadav has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Janssen Pharmaceuticals. Dr. Yadav has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Bristol Myers Squibb Foundation. Dr. Yadav has received personal compensation in the range of $500-$4,999 for serving as a Consultant for EMD-Serono . The institution of Dr. Yadav has received research support from Department of Veterans Affairs. Dr. Yadav has received research support from NIH. Dr. Yadav has received research support from PCORI. Dr. Yadav has received research support from NMSS. The institution of Dr. Yadav has received research support from Department of Veterans Affairs. The institution of Dr. Yadav has received research support from Tykeson Family Foundation Endowed Professorship.

Blue Native PAGE-Antibody Shift in Conjunction with Mass Spectrometry to Reveal Protein Subcomplexes: Detection of a Cerebellar α1/α6-Subunits Containing γ-Aminobutyric Acid Type A Receptor Subtype.

The pentameric γ-Aminobutyric acid type A receptors (GABAARs) are ligand-gated ion channels that mediate the majority of inhibitory neurotransmission in the brain. In the cerebellum, the two main receptor subtypes are the 2α1/2β/γ and 2α6/2β/δ subunits. In the present study, an interaction proteomics workflow was used to reveal additional subtypes that contain both α1 and α6 subunits. Immunoprecipitation of the α6 subunit from mouse brain cerebellar extract co-purified the α1 subunit. In line with this, pre-incubation of the cerebellar extract with anti-α6 antibodies and analysis by blue native gel electrophoresis mass-shifted part of the α1 complexes, indicative of the existence of an α1α6-containing receptor. Subsequent mass spectrometry of the blue native gel showed the α1α6-containing receptor subtype to exist in two main forms, i.e., with or without Neuroligin-2. Immunocytochemistry on a cerebellar granule cell culture revealed co-localization of α6 and α1 in post-synaptic puncta that apposed the presynaptic marker protein Vesicular GABA transporter, indicative of the presence of this synaptic GABAAR subtype.