Unveiling the crucial role of betaine: modulation of GABA homeostasis via SLC6A1 transporter (GAT1).

Betaine is an endogenous osmolyte that exhibits therapeutic potential by mitigating various neurological disorders. However, the underlying cellular and molecular mechanisms responsible for its neuroprotective effects remain puzzling.In this study, we describe a possible mechanism behind the positive impact of betaine in preserving neurons from excitotoxicity. Here we demonstrate that betaine at low concentration modulates the GABA uptake by GAT1 (slc6a1), the predominant GABA transporter in the central nervous system. This modulation occurs through the temporal inhibition of the transporter, wherein prolonged occupancy by betaine impedes the swift transition of the transporter to the inward conformation. Importantly, the modulatory effect of betaine on GAT1 is reversible, as the blocking of GAT1 disappears with increased extracellular GABA. Using electrophysiology, mass spectroscopy, radiolabelled cellular assay, and molecular dynamics simulation we demonstrate that betaine has a dual role in GAT1: at mM concentration acts as a slow substrate, and at µM as a temporal blocker of GABA, when it is below its K0.5. Given this unique modulatory characteristic and lack of any harmful side effects, betaine emerges as a promising neuromodulator of the inhibitory pathways improving GABA homeostasis via GAT1, thereby conferring neuroprotection against excitotoxicity.

1,2-Dichloroethane causes anxiety and cognitive dysfunction in mice by disturbing GABA metabolism and inhibiting the cAMP-PKA-CREB signaling pathway.

1,2-Dichloroethane (1,2-DCE) is a powerfully toxic neurotoxin, which is a common environmental pollutant. Studies have indicated that 1,2-DCE long-term exposure can result in adverse effects. Nevertheless, the precise mechanism remains unknown. In this study, behavioral results revealed that 1,2-DCE long-term exposure could cause anxiety and learning and memory ability impairment in mice. The contents of γ-aminobutyric acid (GABA) and glutamine (Gln) in mice's prefrontal cortex decreased, whereas that of glutamate (Glu) increased. With the increase in dose, the activities of glutamate decarboxylase (GAD) decreased and those of GABA transaminase (GABA-T) increased. The protein and mRNA expressions of GABA transporter-3 (GAT-3), vesicular GABA transporter (VGAT), GABA A receptor α2 (GABAARα2), GABAARγ2, K-Cl cotransporter isoform 2 (KCC2), GABA B receptor 1 (GABABR1), GABABR2, protein kinase A (PKA), cAMP-response element binding protein (CREB), p-CREB, brain-derived neurotrophic factor (BDNF), c-fos, c-Jun and the protein of glutamate dehydrogenase (GDH) and PKA-C were decreased, while the expression levels of GABA transporter-1 (GAT-1) and Na-K-2Cl cotransporter isoform 1 (NKCC1) were increased. However, there was no significant change in the protein content of succinic semialdehyde dehydrogenase (SSADH). The expressions of adenylate cyclase (AC) and cyclic adenosine monophosphate (cAMP) contents were also reduced. In conclusion, the results of this study show that exposure to 1,2-DCE could lead to anxiety and cognitive impairment in mice, which may be related to the disturbance of GABA metabolism and its receptors along with the cAMP-PKA-CREB pathway.

Pharmacological evaluation of E2730, a novel selective uncompetitive GAT1 inhibitor, on epileptiform activities in resected brain tissues from human focal cortical dysplasia ex vivo.

Focal cortical dysplasia (FCD) is an important etiology of focal epilepsy in children and adults. However, only a few preclinical models sufficiently reproduce the characteristic histopathologic features of FCD. To improve the success rate of clinical trials for antiseizure medications (ASMs) in patients with FCD, more human-relevant preclinical models are needed, and epileptic foci resected from patients are a powerful tool for this purpose. Here, we conducted ex vivo studies using epileptic foci resected from patients with FCD type II to evaluate the pharmacologic effects of the ASM candidate E2730, a selective uncompetitive inhibitor of γ-aminobutyric acid transporter 1. We used the same ex vivo assay system to assess carbamazepine (CBZ), an ASM often prescribed for focal epilepsy, as a reference. At the higher dose tested (200 µM), both E2730 and CBZ suppressed spontaneous epileptiform activities almost completely. At the lower dose (100 µM), CBZ reduced the area of brain tissue showing epileptiform activity, whereas E2730 significantly decreased the number of epileptiforms. These findings suggest that E2730-both as a single agent and in combination with CBZ-merits evaluation in clinical trials involving patients with FCD.

PDZ interaction of the GABA transporter GAT1 with the syntenin-1 in Neuro-2a cells.

The GABA transporter GAT1 regulates brain inhibitory neurotransmission and it is considered a potential therapeutic target for the treatment of wide spectrum of neurological diseases including epilepsy, stroke and autism. Syntenin-1 binds to syntaxin 1A, which is known to regulate the plasma membrane insertion of several neurotransmitter transporters. Previously, a direct interaction of syntenin-1 with the glycine transporter GlyT2 was reported. Here, we show that the GABA transporter GAT1 also directly interacts with syntenin-1, involving both unidentified protein interaction interface and the GAT1 C-terminal PDZ binding motif interacting mainly with syntenin-1 PDZ domain 1. The PDZ interaction was eliminated by the mutation of GAT1 isoleucine 599 and tyrosine 598 located in PDZ positions 0 and -1, respectively. This indicates an unconventional PDZ interaction and possible regulation of the transporter PDZ motif via tyrosine phosphorylation. Whole syntenin-1 protein fused to GST protein and immobilised on glutathione resin coprecipitated intact GAT1 transporter from an extract of GAT1 transfected neuroblastoma N2a cells. This coprecipitation was inhibited by tyrosine phosphatases inhibitor pervanadate. The fluorescence tagged GAT1 and syntenin-1 colocalized upon coexpression in N2a cells. The above results show that syntenin-1 might be, in addition to GlyT2, directly involved in the trafficking of GAT1 transporter.

Hyperosmotic Stress Allosterically Reconfigures Betaine Binding Pocket in BetP.

The transporter BetP in C. glutamicum is essential in maintaining bacterial cell viability during hyperosmotic stress and functions by co-transporting betaine and Na+ into bacterial cells. Hyperosmotic stress leads to increased intracellular K+ concentrations which in turn promotes betaine binding. While structural details of multiple end state conformations of BetP have provided high resolution snapshots, how K+ sensing by the C-terminal domain is allosterically relayed to the betaine binding site is not well understood. In this study, we describe conformational dynamics in solution of BetP using amide hydrogen/deuterium exchange mass spectrometry. These reveal how K+ alters conformation of the disordered C- and N-terminal domains to allosterically reconfigure transmembrane helices 3, 8, and 10 to enhance betaine interactions. A map of the betaine binding site, at near single amino acid resolution, reveals a critical extrahelical H-bond mediated by TM3 with betaine.

Synthesis of γ-Aminobutyric Acid (GABA) Analogues Conformationally Restricted by Bicyclo[3.1.0]hexane/hexene or [4.1.0]Heptane/heptene Backbones as Potent Betaine/GABA Transporter Inhibitors.

Novel γ-aminobutyric acid (GABA) analogues 3-5, having a bicyclo[3.1.0]hexene, [4.1.0]heptane, or [4.1.0]heptene backbone, respectively, were designed from the bioactive form analysis of the previous inhibitor 2 with a bicyclo[3.1.0]hexane backbone. Compounds 3-5 and 2 were synthesized from a common 1,7-diene intermediate 6 using ring-closing metathesis (RCM) to construct the key bicyclo backbones. Compounds 3-5 strongly inhibit betaine/GABA transporter 1 (BGT1) uptake, but compound 4 stands out with its selective low micromolar potency.

Integrated Analysis of DNA Repair Genes Identifies SLC6A1 as a New Marker for the Clinical Outcome of Patients with Colorectal Cancer.

Colorectal cancer (CRC) remains an important malignancy worldwide with poor prognosis. It has been known that DNA repair genes are involved in the development and progression of various tumors. Therefore, the purpose of this study was to explore DNA repair gene-based prognostic biomarkers for CRC. In this study, the expressing pattern and prognostic values of DNA repair genes in CRC patients were analyzed using TCGA database. GO and KEGG enrichment analyses were conducted to clarify the functional roles of dysregulated genes. We observed 358 differentially expressed DNA repair genes in CRC specimens, including 84 downregulated genes and 275 upregulated genes. 36 survival-related DNA repair genes were correlated with CRC patients' five-year survival, including 6 low-risk genes and 30 high-risk genes. Among the 10 overlapping genes, we focused on SLC6A1 which was highly expressed in CRC, and multivariate analysis confirmed that SLC6A1 expression as well as age and clinical stage could be regarded as an independent predicting factor for CRC prognosis. KEGG assays revealed that SLC6A1 may influence the clinical progression via regulating TGF-beta and PI3K-Akt signaling pathways. In addition, we observed that SLC6A1 was negatively regulated by SLC6A1 methylation, leading to its low expression in CRC specimens. Overall, SLC6A1 is upexpressed in CRC and can be used as a marker of poor prognosis in CRC patients.

Metabolomics Analysis of the Effect of GAT-2 Deficiency on Th1 Cells in Mice.

The classic neurotransmitter γ-aminobutyric acid (GABA) has been shown to shape the activation and function of immune cells. There are four high-affinity GABA transporters (GATs, including GAT-1, GAT-2, GAT-3, and GAT-4) responsible for the transmembrane transport of GABA in mice. To explore the effect of GAT-2 on type 1 helper T (Th1) cells, naïve CD4+ T cells were isolated from splenocytes of GAT-2 knockout (KO) and wild-type (WT) mice and cultured for Th1 cell differentiation, and then, metabolomics analysis of Th1 cells was performed via gas chromatography coupled to time-of-flight mass spectrometry added with multivariate analyses. Based on the variable importance projection value > 1 and P < 0.05, a total of nine differentially expressed metabolites (DEMs) were identified between WT and KO. Then, DEMs were mapped to the KEGG database, and five metabolic pathways were significantly enriched, including the cysteine and methionine metabolism, the riboflavin metabolism, the purine metabolism, the glycerolipid metabolism, and the glycerophospholipid metabolism. Collectively, our metabolomics analysis revealed that deficiency of GAT-2 influenced the metabolomics profile of Th1 cells, which will provide insights into T cell response to GAT-2 deficiency in mice. Data are available via MetaboLights with identifier MTBLS3358.

Osmoregulatory Role of Betaine and Betaine/γ-Aminobutyric Acid Transporter 1 in Post-Traumatic Syringomyelia.

Syringomyelia (SM) is primarily characterized by the formation of a fluid-filled cyst that forms in the parenchyma of the spinal cord following injury or other pathology. Recent omics studies in animal models have identified dysregulation of solute carriers, channels, transporters, and small molecules associated with osmolyte regulation during syrinx formation/expansion in the spinal cord. However, their connections to syringomyelia etiology are poorly understood. In this study, the biological functions of the potent osmolyte betaine and its associated solute carrier betaine/γ-aminobutyric acid (GABA) transporter 1 (BGT1) were studied in SM. First, a rat post-traumatic SM model was used to demonstrate that the BGT1 was primarily expressed in astrocytes in the vicinity of syrinxes. In an in vitro system, we found that astrocytes uptake betaine through BGT1 to regulate cell size under hypertonic conditions. Treatment with BGT1 inhibitors, especially NNC 05-2090, demonstrated midhigh micromolar range potency in vitro that reversed the osmoprotective effects of betaine. Finally, the specificity of these BGT1 inhibitors in the CNS was demonstrated in vivo, suggesting feasibility for targeting betaine transport in SM. In summary, these data provide an enhanced understanding of the role of betaine and its associated solute carrier BGT1 in cell osmoregulation and implicates the active role of betaine and BGT1 in syringomyelia progression.

Expression of uroplakin II and GATA-3 in bladder cancer mimickers: caveats in the use of a limited panel to determine cell of origin in bladder lesions.

Antibodies targeting uroplakin II (UPII) are highly specific for urothelial cells and are frequently used to determine if a primary bladder lesion or a metastatic lesion originates from the urothelium. However, to date, no studies have tested the expression of UPII in histological mimickers of bladder cancer that are nonurothelial in origin. Given the potential risk of misdiagnosis, immunohistochemical markers are often used to better characterize these lesions. In the present study, we analyzed the immunohistochemical expression of UPII in a set of urothelial carcinoma mimickers that included conventional nephrogenic adenoma (n = 8), papillary nephrogenic adenoma (n = 6), endometriosis/endosalpingiosis (n = 5), inflammatory myofibroblastic tumor (n = 4), ectopic prostate tissue (n = 2), and malakoplakia (n = 2). We also examined the expression of GATA-3, another commonly used immunohistochemical marker in bladder cancer diagnosis, in the same lesions. Weak immunoreactivity for UPII was identified in 6 of 27 mimickers (22%), and GATA-3 was expressed in 16 of 27 mimickers (59%). Strong immunoreactivity for UPII appeared to be a specific marker for urothelial cell of origin, although weak staining was seen in a significant proportion of mimickers. GATA-3 immunostaining was present in a greater number and broader spectrum of mimickers; however, only one case of papillary nephrogenic adenoma showed dual positivity for UPII and GATA-3. These findings support the immunohistochemical panel-based approach in the diagnosis of bladder lesions, especially if nonurothelial bladder cancer mimickers are in the differential diagnosis. Additional larger studies would be of value to expand on these findings.

GABA transporter sustains IL-1ß production in macrophages.

Accumulating evidence shows that nervous system governs host immune responses; however, how γ-aminobutyric acid (GABA)ergic system shapes the function of innate immune cells is poorly defined. Here, we demonstrate that GABA transporter (GAT2) modulates the macrophage function. GAT2 deficiency lowers the production of interleukin-1ß (IL-1ß) in proinflammatory macrophages. Mechanistically, GAT2 deficiency boosts the betaine/S-adenosylmethionine (SAM)/hypoxanthine metabolic pathway to inhibit transcription factor KID3 expression through the increased DNA methylation in its promoter region. KID3 regulates oxidative phosphorylation (OXPHOS) via targeting the expression of OXPHOS-related genes and is also critical for NLRP3-ASC-caspase-1 complex formation. Likewise, GAT2 deficiency attenuates macrophage-mediated inflammatory responses in vivo, including lipopolysaccharide-induced sepsis, infection-induced pneumonia, and high-fat diet-induced obesity. Together, we propose that targeting GABAergic system (e.g., GABA transporter) could provide previously unidentified therapeutic opportunities for the macrophage-associated diseases.

Functional Characterization of the γ-Aminobutyric Acid Transporter from Mycobacterium smegmatis MC2 155 Reveals Sodium-Driven GABA Transport.

Characterizing the mycobacterial transporters involved in the uptake and/or catabolism of host-derived nutrients required by mycobacteria may identify novel drug targets against tuberculosis. Here, we identify and characterize a member of the amino acid-polyamine-organocation superfamily, a potential γ-aminobutyric acid (GABA) transport protein, GabP, from Mycobacterium smegmatis The protein was expressed to a level allowing its purification to homogeneity, and size exclusion chromatography coupled with multiangle laser light scattering (SEC-MALLS) analysis of the purified protein showed that it was dimeric. We showed that GabP transported γ-aminobutyric acid both in vitro and when overexpressed in E. coli Additionally, transport was greatly reduced in the presence of ß-alanine, suggesting it could be either a substrate or inhibitor of GabP. Using GabP reconstituted into proteoliposomes, we demonstrated that γ-aminobutyric acid uptake is driven by the sodium gradient and is stimulated by membrane potential. Molecular docking showed that γ-aminobutyric acid binds MsGabP, another Mycobacterium smegmatis putative GabP, and the Mycobacterium tuberculosis homologue in the same manner. This study represents the first expression, purification, and characterization of an active γ-aminobutyric acid transport protein from mycobacteria.IMPORTANCE The spread of multidrug-resistant tuberculosis increases its global health impact in humans. As there is transmission both to and from animals, the spread of the disease also increases its effects in a broad range of animal species. Identifying new mycobacterial transporters will enhance our understanding of mycobacterial physiology and, furthermore, provides new drug targets. Our target protein is the gene product of msmeg_6196, annotated as GABA permease, from Mycobacterium smegmatis strain MC2 155. Our current study demonstrates it is a sodium-dependent GABA transporter that may also transport ß-alanine. As GABA may well be an essential nutrient for mycobacterial metabolism inside the host, this could be an attractive target for the development of new drugs against tuberculosis.

Role of TaALMT1 malate-GABA transporter in alkaline pH tolerance of wheat.

Malate exudation through wheat (Triticum aestivum L) aluminium-activated malate transporter 1 (TaALMT1) confers Al3+ tolerance at low pH, but is also activated by alkaline pH, and is regulated by and facilitates significant transport of gamma-aminobutyric acid (GABA, a zwitterionic buffer). Therefore, TaALMT1 may facilitate acidification of an alkaline rhizosphere by promoting exudation of both malate and GABA. Here, the performance of wheat near isogenic lines ET8 (Al+3 -tolerant, high TaALMT1 expression) and ES8 (Al+3 -sensitive, low TaALMT1 expression) are compared. Root growth (at 5 weeks) was higher for ET8 than ES8 at pH 9. ET8 roots exuded more malate and GABA at high pH and acidified the rhizosphere more rapidly. GABA and malate exudation was enhanced at high pH by the addition of aluminate in both ET8 and transgenic barley expressing TaALMT1. Xenopus laevis oocytes expressing TaALMT1 acidified an alkaline media more rapidly than controls corresponding to higher GABA efflux. TaALMT1 expression did not change under alkaline conditions but key genes involved in GABA turnover changed in accordance with a high rate of GABA synthesis. We propose that TaALMT1 plays a role in alkaline tolerance by exuding malate and GABA, possibly coupled to proton efflux.

SLC6A1 G443D associated with developmental delay and epilepsy.

SLC6A1 is associated with an autosomal dominant early-onset seizure and epileptic encephalopathy associated with intellectual disability. We present a 2-yr-old girl with developmental delay and epilepsy, using a new computational filtering impact score to show the patient's variant ranks with other pathogenic variants. Genomic studies within the patient revealed a G443D variant of uncertain significance. Structural and evolutionary assessments establish this variant as a loss of function to the protein. Compiled metrics through our custom tools on sequence, structure, and protein dynamics combined with PolyPhen-2, PROVEAN, SIFT, and Align-GVGD reveal this variant to rank in the top functional outcome changes relative to gnomAD, TOPMed, and ClinVar variants known to date. The patient was resistant to multiple epileptic drugs, finally finding that valproic acid controls the seizures. This is consistent with additional groups studying SLC6A1 variants within patients.

Papillary Renal Neoplasm With Reverse Polarity: A Clinicopathologic Study of 7 Cases.

Papillary renal neoplasm with reverse polarity is a form of recently described tumor. These tumors are defined by GATA3 positivity, negative vimentin staining, and the presence of both papillary structures and a layer of eosinophilic cells with apical nuclei and a granular cytoplasm. In the present report, we review 7 cases of papillary renal neoplasm with reverse polarity that were GATA3+ and vimentin-, consistent with past reports. In all 7 of these cases, we found that these tumors were additionally positive for 34ßE12. All 7 of these tumors were categorized as stage pT1. On histological examination, these tumors exhibited branching papillae with apical nuclei. All 7 of these patients were alive on most recent follow-up, with 6 being disease free and one having developed prostate cancer. Together, this overview of 7 additional cases of papillary renal neoplasm with reverse polarity offers further insight into this rare and poorly understood disease.

Overexpression of SLC6A1 associates with drug resistance and poor prognosis in prostate cancer.

BACKGROUND: Solute Carrier Family 6 Member 1 (SLC6A1) has been identified as a cancer-promoting gene in various human cancers, such as clear cell renal cell carcinoma and ovarian cancer. However, its roles in prostate cancer (PCa) has not been fully elucidated. The aim of this study was to investigate the expression and clinical significance of SLC6A1 in PCa tissues and its effect on drug resistance to docetaxel in PCa. METHODS: Expression patterns of SLC6A1 protein in PCa tissues were examined by immunohistochemistry based on Tissue microarray. Associations of SLC6A1 protein expression with various clinicopathological features and patients' prognosis of PCa were also statistically evaluated based on TCGA data. Roles of SLC6A1 deregulation in prostate carcinogenesis and drug resistance was further determined in vitro and in vivo experiments. RESULTS: Based on TCGA Dataset, SLC6A1 expression was markedly higher in patients with high Gleason score, advanced clinical stage and positive biochemical recurrence than those with control features (all P < 0.05). Both unvariate and multivariate analyses demonstrated that SLC6A1 expression was significantly associated with biochemical recurrence-free survival in PCa patients. In addition, enforced expression of SLC6A1 effectively promoted cell proliferation, migration and invasion of PCa cells in vitro. Moreover, the inhibition of SLC6A1 suppressed the tumor growth in vivo. Additionally, immunohistochemical notches of PCNA and MMP-9 in the low-expression cluster were pointedly lower compared to those of NC group. Finally, the cell viability revealed that the overexpression of SLC6A1 obviously promoted the PCa cell resistant to docetaxel (DTX), and the transplanted tumor in the overexpression group had no significant reduction compared with the untreated group. CONCLUSIONS: Our data suggest that SLC6A1 overexpression may be associated with aggressive progression and short biochemical recurrence-free survival of PCa, and may be related to the resistance to docetaxel therapy.

Protein kinases as regulators of osmolyte accumulation under stress conditions: An overview.

Accumulation of osmolytes, during cell volume perturbations, as cell volume regulators is ensured through their de novo synthesis, decreased degradation and transport from their site of synthesis to the site of utility through various transport systems. Among these, transport system mediated accumulation has been observed to be quite significant during long term cell volume perturbation. Under stress conditions, these osmolyte transporters are regulated at transcriptional as well as translational level. At translational level, protein kinases carry out phosphorylation of osmolyte transporters and have been shown to play a crucial role in cell volume homeostasis. In fact phosphorylation of osmolyte transporters on their conserved residues regulates the uptake and efflux of osmolytes by cells. Additionally, accumulated osmolytes in turn have been shown to modulate the structure and functioning of protein kinases. The present review has tried to provide an overview about the role of protein kinases in regulation of osmolyte accumulation under stress conditions. Due to their ability of regulating osmolyte accumulation, potential of protein kinases as therapeutic targets for diseases like cancer has also been highlighted.

Conditional Single Vector CRISPR/SaCas9 Viruses for Efficient Mutagenesis in the Adult Mouse Nervous System.

Mice engineered for conditional, cell type-specific gene inactivation have dominated the field of mouse genetics because of the high efficiency of Cre-loxP-mediated recombination. Recent advances in CRISPR/Cas9 technologies have provided alternatives for rapid gene mutagenesis for loss-of-function (LOF) analysis. Whether these strategies can be streamlined for rapid genetic analysis with the efficiencies comparable with those of conventional genetic approaches has yet to be established. We show that a single adeno-associated viral (AAV) vector containing a recombinase-dependent Staphylococcus aureus Cas9 (SaCas9) and a single guide RNA (sgRNA) are as efficient as conventional conditional gene knockout and can be adapted for use in either Cre- or Flp-driver mouse lines. The efficacy of this approach is demonstrated for the analysis of GABAergic, glutamatergic, and monoaminergic neurotransmission. Using this strategy, we reveal insight into the role of GABAergic regulation of midbrain GABA-producing neurons in psychomotor activation.

Caffeine regulates GABA transport via A1R blockade and cAMP signaling.

Caffeine is the most consumed psychostimulant drug in the world, acting as a non-selective antagonist of adenosine receptors A1R and A2AR, which are widely expressed in retinal layers. We have previously shown that caffeine, when administered acutely, acts on A1R to potentiate the NMDA receptor-induced GABA release. Now we asked if long-term caffeine exposure also modifies GABA uptake in the avian retina and which mechanisms are involved in this process. Chicken embryos aged E11 were injected with a single dose of caffeine (30 mg/kg) in the air chamber. Retinas were dissected on E15 for ex vivo neurochemical assays. Our results showed that [3H]-GABA uptake was dependent on Na+ and blocked at 4 °C or by NO-711 and caffeine. This decrease was observed after 60 min of [3H]-GABA uptake assay at E15, which is accompanied by an increase in [3H]-GABA release. Caffeine increased the protein levels of A1R without altering ADORA1 mRNA and was devoid of effects on A2AR density or ADORA2A mRNA levels. The decrease of GABA uptake promoted by caffeine was reverted by A1R activation with N6-cyclohexyl adenosine (CHA) but not by A2AR activation with CGS 21680. Caffeine exposure increased cAMP levels and GAT-1 protein levels, which was evenly expressed between E11-E15. As expected, we observed an increase of GABA containing amacrine cells and processes in the IPL, also, cAMP pathway blockage by H-89 decreased caffeine mediated [3H]-GABA uptake. Our data support the idea that chronic injection of caffeine alters GABA transport via A1R during retinal development and that the cAMP/PKA pathway plays an important role in the regulation of GAT-1 function.

[Screening function enrichment and related signaling pathways bioinformatics analysis of differentially expressed gene in glioma].

Objective: To screen the differentially expressed genes, functional enrichment and related signaling pathways in glioma by bioinformatics analysis. Methods: Microarray data of glioma related gene expression profiles were selected in GEO database, and differentially expressed genes in glioma patients and normal brain tissues were screened by R statistical software of lima package. Functional enrichment of differentially expressed genes (GO and KEGG) was performed. The protein-protein interaction database (STRING) was used to analyze the interaction between the screened differentially expressed genes and the related signaling pathways. Results: Two gene expression profiles, GSE15824 and GSE66354, were selected for analysis, and 158 genes with differential expression more than 2 times and P<0.05 were screened. Molecular function (MF) of 158 differentially expressed genes was integrin binding, cell adhesion molecule binding, calcium binding and AMPA glutamate receptor activity. Cell component localization (CC) was located in cell membrane, neuron cell body, axon of nerve cell and so on, while biological process (BP) was mainly cell adhesion and nervous system. Development, cell proliferation, GTPase activity, apoptosis and angiogenesis; KEGG signaling pathways were mainly cAMP signaling pathway, purine metabolism pathway, MAPK signaling pathway and cGMP-PKG signaling pathway. There were 177 interaction connections in 158 differential expression gene-protein interaction networks, with an average interaction of 2.39 between each node and an aggregation coefficient of 0.37. Cytohubb screened the key genes (hub genes) in the signaling pathway. The results indicated that SLC6A1,SLC1A2,BDNF,GAP43,NRXN1,GAD1,OLIG2, PLP1,S100B and GRIA3 were the key genes in the signaling pathway of the interacting protein network. All the 10 key genes were related to the prognosis of patients (P<0.05). Conclusions: There are differentially expressed genes profile in glioma tissues and normal tissues. SLC6A1, SLC1A2, BDNF, GAP43, NRXN1, GAD1, OLIG2, PLP1, S100B and GRIA3 are key genes for glioma development and are related to the prognosis of patients.