ß-Aminoisobutyric acid supplementation attenuated salt-sensitive hypertension in Dahl salt-sensitive rats through prevention of insufficient fumarase.

The human Dietary Approaches to Stop Hypertension-Sodium Trial has shown that ß-aminoisobutyric acid (BAIBA) may prevent the development of salt-sensitive hypertension (SSHT). However, the specific antihypertensive mechanism remains unclear in the renal tissues of salt-sensitive (SS) rats. In this study, BAIBA (100 mg/kg/day) significantly attenuated SSHT via increased nitric oxide (NO) content in the renal medulla, and it induced a significant increase in NO synthesis substrates (L-arginine and malic acid) in the renal medulla. BAIBA enhanced the activity levels of total NO synthase (NOS), inducible NOS, and constitutive NOS. BAIBA resulted in increased fumarase activity and decreased fumaric acid content in the renal medulla. The high-salt diet (HSD) decreased fumarase expression in the renal cortex, and BAIBA increased fumarase expression in the renal medulla and renal cortex. Furthermore, in the renal medulla, BAIBA increased the levels of ATP, ADP, AMP, and ADP/ATP ratio, thus further activating AMPK phosphorylation. BAIBA prevented the decrease in renal medullary antioxidative defenses induced by the HSD. In conclusion, BAIBA's antihypertensive effect was underlined by the phosphorylation of AMPK, the prevention of fumarase's activity reduction caused by the HSD, and the enhancement of NO content, which in concert attenuated SSHT in SS rats.

Metabolomics of Escherichia coli Treated with the Antimicrobial Carbon Monoxide-Releasing Molecule CORM-3 Reveals Tricarboxylic Acid Cycle as Major Target.

In the last decade, carbon monoxide-releasing molecules (CORMs) have been shown to act against several pathogens and to be promising antimicrobials. However, the understanding of the mode of action and reactivity of these compounds on bacterial cells is still deficient. In this work, we used a metabolomics approach to probe the toxicity of the ruthenium(II) complex Ru(CO)3Cl(glycinate) (CORM-3) on Escherichia coli By resorting to 1H nuclear magnetic resonance, mass spectrometry, and enzymatic activities, we show that CORM-3-treated E. coli accumulates larger amounts of glycolytic intermediates, independently of the oxygen growth conditions. The work provides several evidences that CORM-3 inhibits glutamate synthesis and the iron-sulfur enzymes of the tricarboxylic acid (TCA) cycle and that the glycolysis pathway is triggered in order to establish an energy and redox homeostasis balance. Accordingly, supplementation of the growth medium with fumarate, α-ketoglutarate, glutamate, and amino acids cancels the toxicity of CORM-3. Importantly, inhibition of the iron-sulfur enzymes glutamate synthase, aconitase, and fumarase is only observed for compounds that liberate carbon monoxide. Altogether, this work reveals that the antimicrobial action of CORM-3 results from intracellular glutamate deficiency and inhibition of nitrogen and TCA cycles.

Comparative bioenergetic assessment of transformed cells using a cell energy budget platform.

The aberrant expression and functional activity of proteins involved in ATP production pathways may cause a crisis in energy generation for cells and compromise their survival under stressful conditions such as excitation, starvation, pharmacological treatment or disease states. Under resting conditions such defects are often compensated for, and therefore masked by, alternative pathways which have significant spare capacity. Here we present a multiplexed 'cell energy budget' platform which facilitates metabolic assessment and cross-comparison of different cells and the identification of genes directly or indirectly involved in ATP production. Long-decay emitting O(2) and pH sensitive probes and time-resolved fluorometry are used to measure changes in cellular O(2) consumption, glycolytic and total extracellular acidification (ECA), along with the measurement of total ATP and protein content in multiple samples. To assess the extent of spare capacity in the main energy pathways, the cells are also analysed following double-treatment with carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone and oligomycin. The four-parametric platform operating in a high throughput format has been validated with two panels of transformed cells: mouse embryonic fibroblasts (MEFs) lacking the Krebs cycle enzyme fumarate hydratase (Fh1) and HeLa cells with reduced expression of pyrimidine nucleotide carrier 1. In both cases, a marked reduction in both respiration and spare respiratory capacity was observed, accompanied by a compensatory activation of glycolysis and consequent maintenance of total ATP levels. At the same time, in Fh1-deficient MEFs the contribution of non-glycolytic pathways to the ECA did not change.

UOK 262 cell line, fumarate hydratase deficient (FH-/FH-) hereditary leiomyomatosis renal cell carcinoma: in vitro and in vivo model of an aberrant energy metabolic pathway in human cancer.

Energy deregulation and abnormalities of tumor cell metabolism are critical issues in understanding cancer. Hereditary leiomyomatosis renal cell carcinoma (HLRCC) is an aggressive form of RCC characterized by germline mutation of the Krebs cycle enzyme fumarate hydratase (FH), and one known to be highly metastatic and unusually lethal. There is considerable utility in establishing preclinical cell and xenograft models for study of disorders of energy metabolism, as well as in development of new therapeutic approaches targeting of tricarboxylic acid (TCA) cycle enzyme-deficient human cancers. Here we describe a new immortalized cell line, UOK 262, derived from a patient having aggressive HLRCC-associated recurring kidney cancer. We investigated gene expression, chromosome profiles, efflux bioenergetic analysis, mitochondrial ultrastructure, FH catabolic activity, invasiveness, and optimal glucose requirements for in vitro growth. UOK 262 cells have an isochromosome 1q recurring chromosome abnormality, i(1)(q10), and exhibit compromised oxidative phosphorylation and in vitro dependence on anaerobic glycolysis consistent with the clinical manifestation of HLRCC. The cells also display glucose-dependent growth, an elevated rate of lactate efflux, and overexpression of the glucose transporter GLUT1 and of lactate dehydrogenase A (LDHA). Mutant FH protein was present primarily in edematous mitochondria, but with catalytic activity nearly undetectable. UOK 262 xenografts retain the characteristics of HLRCC histopathology. Our findings indicate that the severe compromise of oxidative phosphorylation and rapid glycolytic flux in UOK 262 are an essential feature of this TCA cycle enzyme-deficient form of kidney cancer. This tumor model is the embodiment of the Warburg effect. UOK 262 provides a unique in vitro and in vivo preclinical model for studying the bioenergetics of the Warburg effect in human cancer.

Fumarase deficiency presenting with periventricular cysts.

A fumarase-deficient patient expressed a novel phenotype of congenital cerebral ventricular dilatation and periventricular cysts. The patient was a compound heterozygote for two mutations that are the only ones among the 12 published mutations that have been found in multiple, unrelated, fumarase-deficient patients.