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:Corynebacterium glutamicum shows a great potential for the production of gamma-aminobutyric acid (GABA) from glucose fermentation via putrescine. GABA, a non-protein amino acid widespread in nature, is a component of pharmaceuticals, foods and the biodegradable plastic polyamide 4. Here, the effect of GABA in the growth of C. glutamicum was evaluated. It was estimated that the presence 1.1 M of GABA in the medium reduces the maximum growth rate of C. glutamicum to half. It was also shown that the presence of GABA in the medium negatively affects the growth of C. glutamicum in ethanol as sole carbon source. Furthermore, a new route for the production of GABA in C. glutamicum was established. GABA production from glucose fermentation via putrescine was achieved by plasmid-based overexpression of putrescine transaminase (PatA) and gamma-aminobutyraldehyde dehydrogenase (PatD) in a putrescine production strain. The resultant strain can produce 5.3 ± 0.1 g L-1 of GABA. GABA production was improved by avoiding the formation of N-acetylputrescine and by reducing the amount of nitrogen in CGXII medium. Deletion of the genes responsible for GABA catabolism and GABA re-uptake led to an increase in the GABA production of 21% achieving a titer 8.0 ± 0.3 g L-1 and an increase in the volumetric productivity of 41% reaching a productivity of 0.31 g L-1 h-1, the highest volumetric productivity achieved so far for GABA production in C. glutamicum from glucose fermentation in flasks fermentations. The results obtained hitherto are very promising and competitive compared to the traditional pathway for the production of GABA.
Project description:UPLC-MS/MS data used to confirm the retention times of bile acid conjugates to GABA and tyramine that were detected in microbial culture and human fecal samples. Synthesized conjugates included here are GABA-deoxycholic acid, tyramine-deoxycholic acid, GABA-cholic acid, tyramine-cholic acid, GABA-chenodeoxycholic acid, and tyramine-chenodeoxycholic acid. Data of biological samples (B. fragilis P207 spiked with DCA, healthy human donor 11 feces, patient 207 v12 feces) from the same UPLCMS/MS sequence is included for comparison and validation. All using positive ionization.
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