Project description:Metabolic programs of immune cells are closely linked to their effector functions , where physiological molecules provide environmental cues and guidance. Exactly how it happens is still being unraveled. Insulin maintains normal blood glucose levels and glucose is themain source of energy and a precursor for many biomolecules in T cells, whereas γ-aminobutyric acid (GABA), best known as a neurotransmitter, is increasingly recognized as a regulatory molecule in the immune system. Here, we demonstrate that GABA-mediated reduction of metabolic activity and release of inflammatory molecules, including IFNγ and IL-10, was abolished in human CD4+ T cells, when the glucose concentration was elevated above normal levels. In a glucose concentration-dependent manner, insulin enhanced the GABAA receptors activated currents and GABA-dependent Ca2+ influx. GABA decreased, whereas insulin maintained glycolysis but in a SGLT (Na + -glucose transporter)-dependent manner, revealing expression of SGLTs in activated CD4+ T cells. The SGLTs antagonist phlorizin, alone or together with GABA, restored the inhibition of IFNγ and IL-10 release in presence of high glucose. This study exposes concerted effects of GABA, glucose and insulin on CD4+ T cells metabolic activity and release of inflammatory molecules, and identifies a role for SGLTs in CD4+ T cells function.
Project description:Hepatic lipid accumulation is a hallmark of type 2 diabetes (T2D) and associated with hyperinsulinemia, insulin resistance, and hyperphagia. Hepatic synthesis of GABA, catalyzed by GABA-transaminase (GABA-T), is upregulated in obese mice. To assess the role of hepatic GABA production in obesity-induced metabolic and energy dysregulation, we treated mice with two pharmacologic GABA-T inhibitors and also knocked down hepatic GABA-T expression using an antisense oligonucleotide. Hepatic GABA-T inhibition and knockdown decreased basal hyperinsulinemia and hyperglycemia, and improved glucose intolerance. GABA-T knockdown improved insulin sensitivity assessed by hyperinsulinemic-euglycemic clamps in obese mice. Hepatic GABA-T knockdown also decreased food intake and induced weight loss without altering energy expenditure in obese mice. Data from obese humans support that hepatic GABA production and transport are associated with serum insulin, HOMA-IR, T2D, and BMI. These results support a key role for hepatocyte GABA production in the dysfunctional glucoregulation and feeding behavior associated with obesity.
Project description:γ-Aminobutyric acid (GABA) is a non-proteinogenic amino acid and widespread in nature from microorganisms to plants and animals. DNA microarray analysis revealed that the transcription of gabTDP was strongly increased in C. glutamicum wild type grown with GABA and urea compared to the same strain cultivated with glucose and urea. Remarkably, the presence of ammonia partially inhibited growth on GABA, and the reasons for it were also investigated in this study.
Project description:Neurotransmitters have been well-documented to determine immune cell fates; however, whether and how γ-amino butyric acid (GABA) shapes the function of innate immune cells is still obscure. Here, we demonstrated that GABA orchestrates macrophage maturation and inflammation. GABA treatment during macrophage maturation inhibits interleukin (IL)-1β production from inflammatory macrophages. Mechanistically, GABA enhances succinate-FAD-lysine demethylase1 (LSD1) signaling to regulate the histone demethylation of Bcl2l11 and Dusp2, lowering the formation of NLRP3-ASC-Caspase-1 complex. Meanwhile, GABA-succinate axis lowers succinylation of mitochondrial proteins to promote mitochondrial oxidative phosphorylation (OXPHOS). We also found that GABA alleviates the LPS-induced sepsis as well as high-fat diet-induced obesity in mice. Our study proves that GABA is potential in lessening the pro-inflammatory macrophage responses associating with metabolic reprogramming and protein succinylation, thus providing a strategy for treating macrophage-related inflammatory diseases.
Project description:Background: Of the many neurotransmitters in humans, gamma-aminobutyric acid (GABA) shows potential for improving several mental health indications such as stress and anxiety. The microbiota-gut-brain axis is an important pathway for GABAergic effects, as microbially-secreted GABA within the gut can affect host mental functionhealth outcomes. Understanding the molecular characteristics of GABA production by microbes within the gut can offer insight to novel therapies for mental health. Results: Three strains of Levilactobacillus brevis with syntenous glutamate decarboxylase (GAD) operons were evaluated for overall growth, glutamate utilization, and GABA production in typical synthetic growth media supplemented with monosodium glutamate (MSG). Levilactobacillus brevis Lbr-6108 (Lbr-6108) and Levilactobacillus brevis Lbr-35 (Lbr-35) had similar growth profiles but differed significantly in GABA secretion and acid resistance. Lbr-6108 produced GABA early, within the growth phase, and produced significantly more GABA than Lbr-35 and the type strain Levilactobacillus brevis ATCC 14689 after the stationary phase. The global gene expression during GABA production was determined by RNA sequencing at several timepoints. The GAD operon, responsible for GABA production and secretion, activated in Lbr-6108 after only six hours of fermentation and continued throughout the stationary phase. Furthermore, Lbr-6108 activated many different acid resistance mechanisms concurrently, which contribute to acid tolerance and energy production. In contrast, Lbr-35, which has a genetically similar GAD operon, including two copies of the GAD gene, showed no upregulation of the GAD operon, even when cultured with MSG. Conclusions: This study is the first to evaluate whole transcriptome changes in L. brevis during GABA production over multiple timepoints. The concurrent expression of multiple acid-resistance mechanisms reveals niche-specific metabolic functionality between common human commensals and highlights the complex regulation of GABA metabolism in this important microbial species. Furthermore, the increased and rapid GABA production of Lbr-6108 highlights the strain’s potential as a therapeutic and the overall value of screening microbes for effector molecule output.
Project description:We have previously shown that GABA ainhibits caspase activation and promote axon regeneration in descending neurons of the sea lamprey brainstem after a complete spinal cord injury. Here, we repeated this treatment and performed Illumina RNA sequencing studies in the brainstems of control and GABA treated animals.
Project description:Insulin receptor (Insr) protein can be found at higher levels in pancreatic b-cells than in most other cell types, but the consequences of b-cell insulin resistance remain enigmatic. Ins1cre allele was used to delete Insr specifically in b-cells of both female and male mice which were compared to Ins1cre-containing littermate controls at multiple ages and on multiple diets. RNA-seq of recombined b-cells revealed significant differences in multiple pathways previously implicated in insulin secretion and cellular fate, including rewired Ras and NFkB signaling. Male, but not female, bInsrKO mice had reduced oxygen consumption rate, while action potential and calcium oscillation frequencies were increased in Insr knockout b-cells from female, but not male mice. Female bInsrKO and bInsrHET mice exhibited elevated insulin release in perifusion experiments, during hyperglycemic clamps, and following i.p. glucose challenge. Deletion of Insr did not reduce b-cell mass up to 9 months of age, nor did it impair hyperglycemia-induced proliferation. Based on our data, we adapted a mathematical model to include b-cell insulin resistance, which predicted that b-cell Insr knockout would improve glucose tolerance depending on the degree of whole-body insulin resistance. Indeed, glucose tolerance was significantly improved in female bInsrKO and bInsrHET mice when compared to controls at 9, 21 and 39 weeks. We did not observe improved glucose tolerance in adult male mice or in high fat diet-fed mice, corroborating the prediction that global insulin resistance obscures the effects of b-cell specific insulin resistance. We further validated our in vivo findings using the Ins1-CreERT transgenic line and found improved glucose tolerance 4 weeks after tamoxifen-mediated Insr deletion. Collectively, our data show that loss of b-cell Insr alone is sufficient to drive glucose-induced hyperinsulinemia, thereby improving glucose homeostasis in otherwise insulin sensitive dietary and age contexts.
Project description:au05-03_gaba - ler vs pop2-1: gaba over-accumulation effects - The analysis aims at identifying genes that are differentially regulated by the over-accumulation of GABA observed in the mutant pop2-1 in response to treatment with exogenous GABA and that may explain the singular phenotype of the mutant in this condition. Designed experiment consisted in comparison of transcriptomes of Arabidopsis thaliana Landsberg erecta ecotype and its mutant pop2-1 (impaired in GABA transaminase activity) during a kinetic of endogenous GABA accumulation. For this purpose, 10-day-old plants grown on half strength Hoagland's agar medium were transferred to agar plates supplemented with 1 mM GABA. We isolated RNA from plants treated for 0, 1 and 4 days. Treatments were made in duplicate. Keywords: gene knock-out, time course 6 dye-swap - CATMA arrays