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Background: GABA (γ-aminobutyric acid) is a non protein amino acid that has been reported to accumulate in a number of plant species when subjected to high salinity and many other environmental constraints. However, no experimental data are to date available on the molecular function of GABA and the involvement of its metabolism in salt stress tolerance in higher plants. Here, we investigated the regulation of GABA metabolism in Arabidopsis thaliana at the metabolite, enzymatic activity and gene transcription levels upon NaCl stress. Results: We identified the GABA transaminase (GABA-T), the first step of GABA catabolism, as the most responsive to NaCl. We further performed a functional analysis of the corresponding gene POP2 and demonstrated that the previously isolated loss-of-function pop2-1 mutant was oversensitive to ionic stress but not to osmotic stress suggesting a specific role in salt tolerance. NaCl oversensitivity was not associated with overaccumulation of Na+ and Cl- but mutant showed a slight decrease in K+. To bring insights into POP2 function, a promoter-reporter gene strategy was used and showed that POP2 was mainly expressed in roots under control conditions and was induced in primary root apex and aerial parts of plants in response to NaCl. Additionally, GC-MS- and UPLC-based metabolite profiling revealed major changes in roots of pop2-1 mutant upon NaCl stress including accumulation of amino acids and decrease in carbohydrates content. Conclusions: GABA metabolism was overall up-regulated in response to NaCl in Arabidopsis. Particularly, GABA-T was found to play a pivotal function and impairment of this step was responsible for a decrease in salt tolerance indicating that GABA catabolism was a determinant of Arabidopsis salt tolerance. GABA-T would act in salt responses in linking N and C metabolisms in roots.

Throughout the course of multiple sclerosis, gradually progressive neurologic impairment can occur, which has been called disability accrual. Current disease-modifying therapies for multiple sclerosis have limited effects on disability accrual unrelated to relapses, which is thought to be partially caused by chronic, nonresolving neuroinflammation within the central nervous system. Tolebrutinib is an oral, brain-penetrant Bruton's tyrosine kinase inhibitor that targets myeloid cells (including microglia) and B cells in both the periphery and central nervous system. There are no approved treatments for nonrelapsing secondary progressive multiple sclerosis. In a phase 3, double-blind, placebo-controlled, event-driven trial, we randomly assigned participants with nonrelapsing secondary progressive multiple sclerosis, in a 2:1 ratio, to receive tolebrutinib (60 mg once daily) or matching placebo. The primary end point was confirmed disability progression that was sustained for at least 6 months, assessed in a time-to-event analysis. A total of 1131 participants underwent randomization: 754 were assigned to receive tolebrutinib and 377 to receive placebo. The median follow-up was 133 weeks. A smaller percentage of participants in the tolebrutinib group than in the placebo group had confirmed disability progression sustained for at least 6 months (22.6% vs. 30.7%; hazard ratio, 0.69; 95% confidence interval, 0.55 to 0.88; P = 0.003). Serious adverse events occurred in 15.0% of the participants in the tolebrutinib group and in 10.4% of those in the placebo group. A total of 4.0% of the participants in the tolebrutinib group and 1.6% of those in the placebo group had increases in alanine aminotransferase levels to more than 3 times the upper limit of the normal range. In participants with nonrelapsing secondary progressive multiple sclerosis, the risk of disability progression was lower among those who received treatment with tolebrutinib than among those who received placebo. (Funded by Sanofi; HERCULES ClinicalTrials.gov number, NCT04411641.).

Serum liver enzyme concentrations are the most frequently-used laboratory markers of liver disease, a major cause of mortality. We conduct a meta-analysis of genome-wide association studies of liver enzymes from UK BioBank and BioBank Japan. We identified 160 previously-unreported independent alanine aminotransferase, 190 aspartate aminotransferase, and 199 alkaline phosphatase genome-wide significant associations, with some affecting multiple different enzymes. Associated variants implicate genes that demonstrate diverse liver cell type expression and promote a range of metabolic and liver diseases. These findings provide insight into the pathophysiology of liver and other metabolic diseases that are associated with serum liver enzyme concentrations. Serum liver enzymes are used as markers of liver disease, their concentration influenced in part by genetic factors. Here the authors meta-analyse genome-wide association studies on the UK Biobank and BioBank Japan to evaluate the association of three liver enzymes with liver and other metabolic diseases.

Serum concentration of hepatic enzymes are linked to liver dysfunction, metabolic and cardiovascular diseases. We perform genetic analysis on serum levels of alanine transaminase (ALT), alkaline phosphatase (ALP) and gamma-glutamyl transferase (GGT) using data on 437,438 UK Biobank participants. Replication in 315,572 individuals from European descent from the Million Veteran Program, Rotterdam Study and Lifeline study confirms 517 liver enzyme SNPs. Genetic risk score analysis using the identified SNPs is strongly associated with serum activity of liver enzymes in two independent European descent studies (The Airwave Health Monitoring study and the Northern Finland Birth Cohort 1966). Gene-set enrichment analysis using the identified SNPs highlights involvement in liver development and function, lipid metabolism, insulin resistance, and vascular formation. Mendelian randomization analysis shows association of liver enzyme variants with coronary heart disease and ischemic stroke. Genetic risk score for elevated serum activity of liver enzymes is associated with higher fat percentage of body, trunk, and liver and body mass index. Our study highlights the role of molecular pathways regulated by the liver in metabolic disorders and cardiovascular disease. Plasma levels of liver enzymes provide insights into hepatic function and related diseases. Here, the authors perform a genome-wide association study on three liver enzymes, identifying genetic variants associated with their plasma concentration as well as links to metabolic and cardiovascular diseases.

A ( S )-selective amine transaminase from a Streptomyces strain, Sbv333-ATA, is a biocatalyst showing both high thermostability with a melting temperature of 85 °C and broad substrate specificity for the amino acceptor. This enzyme was further characterized both biochemically and structurally. The Sbv333-ATA is stable in the presence of up to 20% ( v / v ) of the water-miscible cosolvents methanol, ethanol, acetonitrile, and dimethyl sulfoxide, and in biphasic systems with petroleum ether, toluene, and ethyl acetate as an organic phase. The enzyme showed also a good activity toward different amino donors, such as ( S )-methylbenzylamine and 2-phenylethylamine, aliphatic mono- and di-amines, like propylamine and cadaverine, and selected amino acids. However, more sterically hindered aromatic amines were not accepted. Based on the knowledge of the three-dimensional structures obtained, a rational approach to site specific mutagenesis was carried out to broaden the substrate specificity of Sbv333-ATA. The mutant W89A showed the highest activity toward bulky amines as substrates, such as the diaromatic compound 1,2-diphenylethylamine. The 3D structures of the holo and inhibitor gabaculine bound forms of native Sbv333-ATA, and holo W89A and F61C mutants were determined at high resolutions of 1.49, 1.24, and 1.31 (both mutants) Å, respectively. These structures were important for revealing further details of the active site binding pockets of the Sbv333-ATA and its mechanism. Key points • Sbv333-ATA is a highly thermostable transaminase with a broad substrate scope. • Sbv333-ATA remains active in various organic cosolvents and biphasic systems. • Mutant W89A expands substrate range to accept bulky diaromatic amines. Graphical abstract

Previous studies have reported inconsistent results of the associations of alanine transaminase (ALT), aspartate transaminase (AST), gamma-glutamyltransferase (GGT) and alkaline phosphatase (ALP) with incident type 2 diabetes (diabetes hereafter). We aimed to resolve the controversy by taking nonalcoholic fatty liver disease (NAFLD) into account. The study population comprised 132,377 non-diabetic individuals (64,875 men and 67,502 women) aged 35–79 who had two or more health examinations during 1996–2014. A total of 6,555 incident diabetes (3,734 men and 2,821 women) were identified, on average, over 5.8 years of follow-up. Cox regression was used to calculate the hazard ratio (HR) for incident diabetes, adjusting for classical confounders. The risk of incident diabetes was significantly associated with NAFLD [HR = 2.08 (men) and 2.65 (women)]. Elevated ALT, AST, GGT and ALP were also significantly associated with the increased risk of diabetes, with HRs of 1.27, 1.23, 1.58 and 1.37, respectively, in men, and 1.56, 1.18, 1.48 and 1.44, respectively in women. Our results suggest that NAFLD, ALT, AST, GGT and ALP are independent predictors for incident diabetes in both men and women.

Non-alcoholic steatohepatitis (NASH) is characterised by hepatic steatosis, inflammation, hepatocellular injury, and progressive liver fibrosis. Resmetirom (MGL-3196) is a liver-directed, orally active, selective thyroid hormone receptor-β agonist designed to improve NASH by increasing hepatic fat metabolism and reducing lipotoxicity. We aimed to assess the safety and efficacy of resmetirom in patients with NASH. MGL-3196-05 was a 36-week randomised, double-blind, placebo-controlled study at 25 centres in the USA. Adults with biopsy confirmed NASH (fibrosis stages 1–3) and hepatic fat fraction of at least 10% at baseline when assessed by MRI-proton density fat fraction (MRI-PDFF) were eligible. Patients were randomly assigned 2:1 by a computer-based system to receive resmetirom 80 mg or matching placebo, orally once a day. Serial hepatic fat measurements were obtained at weeks 12 and 36, and a second liver biopsy was obtained at week 36. The primary endpoint was relative change in MRI-PDFF assessed hepatic fat compared with placebo at week 12 in patients who had both a baseline and week 12 MRI-PDFF. This trial is registered with ClinicalTrials.gov, number NCT02912260. 348 patients were screened and 84 were randomly assigned to resmetirom and 41 to placebo at 18 sites in the USA. Resmetirom-treated patients (n=78) showed a relative reduction of hepatic fat compared with placebo (n=38) at week 12 (−32·9% resmetirom vs −10·4% placebo; least squares mean difference −22·5%, 95% CI −32·9 to −12·2; p<0·0001) and week 36 (−37·3% resmetirom [n=74] vs −8·5 placebo [n=34]; −28·8%, −42·0 to −15·7; p<0·0001). Adverse events were mostly mild or moderate and were balanced between groups, except for a higher incidence of transient mild diarrhoea and nausea with resmetirom. Resmetirom treatment resulted in significant reduction in hepatic fat after 12 weeks and 36 weeks of treatment in patients with NASH. Further studies of resmetirom will allow assessment of safety and effectiveness of resmetirom in a larger number of patients with NASH with the possibility of documenting associations between histological effects and changes in non-invasive markers and imaging. Madrigal Pharmaceuticals.

In the ongoing phase 3 CheckMate 214 trial, nivolumab plus ipilimumab showed superior efficacy over sunitinib in patients with previously untreated intermediate-risk or poor-risk advanced renal cell carcinoma, with a manageable safety profile. In this study, we aimed to assess efficacy and safety after extended follow-up to inform the long-term clinical benefit of nivolumab plus ipilimumab versus sunitinib in this setting. In the phase 3, randomised, controlled CheckMate 214 trial, patients aged 18 years and older with previously untreated, advanced, or metastatic histologically confirmed renal cell carcinoma with a clear-cell component were recruited from 175 hospitals and cancer centres in 28 countries. Patients were categorised by International Metastatic Renal Cell Carcinoma Database Consortium risk status into favourable-risk, intermediate-risk, and poor-risk subgroups and randomly assigned (1:1) to open-label nivolumab (3 mg/kg intravenously) plus ipilimumab (1 mg/kg intravenously) every 3 weeks for four doses, followed by nivolumab (3 mg/kg intravenously) every 2 weeks; or sunitinib (50 mg orally) once daily for 4 weeks (6-week cycle). Randomisation was done through an interactive voice response system, with a block size of four and stratified by risk status and geographical region. The co-primary endpoints for the trial were overall survival, progression-free survival per independent radiology review committee (IRRC), and objective responses per IRRC in intermediate-risk or poor-risk patients. Secondary endpoints were overall survival, progression-free survival per IRRC, and objective responses per IRRC in the intention-to-treat population, and adverse events in all treated patients. In this Article, we report overall survival, investigator-assessed progression-free survival, investigator-assessed objective response, characterisation of response, and safety after extended follow-up. Efficacy outcomes were assessed in all randomly assigned patients; safety was assessed in all treated patients. This study is registered with ClinicalTrials.gov, number NCT02231749, and is ongoing but now closed to recruitment. Between Oct 16, 2014, and Feb 23, 2016, of 1390 patients screened, 1096 (79%) eligible patients were randomly assigned to nivolumab plus ipilimumab or sunitinib (550 vs 546 in the intention-to-treat population; 425 vs 422 intermediate-risk or poor-risk patients, and 125 vs 124 favourable-risk patients). With extended follow-up (median follow-up 32·4 months [IQR 13·4–36·3]), in intermediate-risk or poor-risk patients, results for the three co-primary efficacy endpoints showed that nivolumab plus ipilimumab continued to be superior to sunitinib in terms of overall survival (median not reached [95% CI 35·6–not estimable] vs 26·6 months [22·1–33·4]; hazard ratio [HR] 0·66 [95% CI 0·54–0·80], p<0·0001), progression-free survival (median 8·2 months [95% CI 6·9–10·0] vs 8·3 months [7·0–8·8]; HR 0·77 [95% CI 0·65–0·90], p=0·0014), and the proportion of patients achieving an objective response (178 [42%] of 425 vs 124 [29%] of 422; p=0·0001). Similarly, in intention-to-treat patients, nivolumab and ipilimumab showed improved efficacy compared with sunitinib in terms of overall survival (median not reached [95% CI not estimable] vs 37·9 months [32·2–not estimable]; HR 0·71 [95% CI 0·59–0·86], p=0·0003), progression-free survival (median 9·7 months [95% CI 8·1–11·1] vs 9·7 months [8·3–11·1]; HR 0·85 [95% CI 0·73–0·98], p=0·027), and the proportion of patients achieving an objective response (227 [41%] of 550 vs 186 [34%] of 546 p=0·015). In all treated patients, the most common grade 3–4 treatment-related adverse events in the nivolumab and ipilimumab group were increased lipase (57 [10%] of 547), increased amylase (31 [6%]), and increased alanine aminotransferase (28 [5%]), whereas in the sunitinib group they were hypertension (90 [17%] of 535), fatigue (51 [10%]), and palmar-plantar erythrodysaesthesia (49 [9%]). Eight deaths in the nivolumab plus ipilimumab group and four deaths in the sunitinib group were reported as treatment-related. The results suggest that the superior efficacy of nivolumab plus ipilimumab over sunitinib was maintained in intermediate-risk or poor-risk and intention-to-treat patients with extended follow-up, and show the long-term benefits of nivolumab plus ipilimumab in patients with previously untreated advanced renal cell carcinoma across all risk categories. Bristol-Myers Squibb and ONO Pharmaceutical.

In order to maintain proper cellular function, the metabolism of the bacterial microbiota presents several mechanisms oriented to keep a correctly balanced amino acid pool. Central components of these mechanisms are enzymes with alanine transaminase activity, pyridoxal 5'-phosphate-dependent enzymes that interconvert alanine and pyruvate, thereby allowing the precise control of alanine and glutamate concentrations, two of the most abundant amino acids in the cellular amino acid pool. Here we report the 2.11-Å crystal structure of full-length AlaA from the model organism Escherichia coli, a major bacterial alanine aminotransferase, and compare its overall structure and active site composition with detailed atomic models of two other bacterial enzymes capable of catalyzing this reaction in vivo, AlaC and valine-pyruvate aminotransferase (AvtA). Apart from a narrow entry channel to the active site, a feature of this new crystal structure is the role of an active site loop that closes in upon binding of substrate-mimicking molecules, and which has only been previously reported in a plant enzyme. Comparison of the available structures indicates that beyond superficial differences, alanine aminotransferases of diverse phylogenetic origins share a universal reaction mechanism that depends on an array of highly conserved amino acid residues and is similarly regulated by various unrelated motifs. Despite this unifying mechanism and regulation, growth competition experiments demonstrate that AlaA, AlaC and AvtA are not freely exchangeable in vivo, suggesting that their functional repertoire is not completely redundant thus providing an explanation for their independent evolutionary conservation.