Fig. 1: GAB is an abundant metabolite produced in TH17 and iTreg cells.
From: GAB functions as a bioenergetic and signalling gatekeeper to control T cell inflammation
a, Experimental scheme of T cell extracellular metabolome profiles (LC–MS). b, Extracellular metabolites associated with amino acid metabolism in the indicated T cell subsets were profiled by LC–MS. The value for each metabolite represents n = 3 biologically independent samples. The heatmap represents the value of the relative amount (see colour scale). The complete metabolomic profile is provided as source data. c,d,j,k, Indicated metabolites were quantified by GC–MS. The value for each metabolite represents n = 3 biologically independent samples. Cysteinylglycine disulfide*, (2R)-2-amino-3-{[2-amino-2-(carboxymethylcarbamoyl)ethyl]disulfanyl}propanoic acid; alpha-ketoglutaramate*, 2-keto-glutaramate; 2-oxoarginine*, 5-[(diaminomethylidene)amino]-2-oxopentanoic acid; 2,3-dihydroxy-5-methylthio-4-pentenoate (DMTPA)*, (2R,3R,4E)-2,3-dihydroxy-5-(methylsulfanyl)pent-4-enoic acid. The heatmaps (c,k) represent the log value (medium) or the absolute value (pellet) of the indicated metabolite quantity (see colour scale). The complete data are provided as source data. The volcano plots (d,j) show changes in metabolites in the cell medium and cell pellet. Heatmaps and volcano plots are representative of n = 3 independent biological samples from n = 2 independent biological experiments. e, Schematic of the pathway of GABA metabolism. f, RNA was isolated from the indicated T cell subsets (n = 3 biologically independent samples) and used for qPCR analyses of the indicated metabolic genes. mRNA levels of Tnai cells were set to 1. The heatmap represents the log value of the relative mRNA expression level (see colour scale). Values and s.d. are provided as source data. g,h, GAB in the indicated groups was determined and quantified by NMR (n = 3 biologically independent samples). i, As illustrated by the experimental scheme (left), GAB production in iTreg and tTreg cells was quantified by a GAB bioassay kit (n = 4 biologically independent samples). Statistical analysis was performed by R (b) or unpaired two-tailed Student’s t-test (c,d,i–k). GAD, glutamate decarboxylase; SSADH, succinic semialdehyde dehydrogenase; SSAR, succinic semialdehyde reductase; GHB-R, γ-hydroxybutyrate receptor; GATs, GABA transporters; VGAT, vesicular GABA transporter; GABAA-R, GABA type A receptor; GABAB-R, GABA type B receptors; DBI, diazepam binding inhibitor.
