The Role of Branched-chain Amino Acids and Their Metabolism in Cardiovascular Diseases

Aspartate restrains thermogenesis by inhibiting the AMPK pathway in adipose tissues

Increasing evidence suggests that brown adipose tissue (BAT) plays an important role in obesity and related diseases. Great progress has been made in identifying positive regulators that activate adipocyte thermogenesis, but negative regulatory signaling of thermogenesis remains poorly understood. Here, we evaluated the potential effects of aspartate on the BAT function. We found that the circulating aspartate level is positively associated with metabolic syndrome and obesity in adults. Acute cold exposure significantly increases BAT aspartate as well as other amino acid levels in mice. In this regard, we speculate that aspartate may play a role in regulating the BAT function and systemic energy homeostasis. To verify the hypothesis, we altered aspartate availability to explore the effects on adipose tissue metabolism. Supplementation of aspartate exogenously inhibits the thermogenic gene expression and cold tolerance in mice. Intriguingly, aspartate bioavailability inhibits mitochondrial biosynthesis essentially through the suppression of mechanistic targeting of the AMPK cascade. Therefore, an evaluation of whether a diet deficient in aspartate will increase oxidative phosphorylation in the mitochondria to reestablish aspartate levels and therefore increase the energy expenditure will be interesting because these effects can prevent or ameliorate the development of obesity.

The toxicity of cisplatin derives from effects on renal organic ion transporters expression and serum endogenous substance levels

Acute kidney injury (AKI) is a worldwide public health problem with high morbidity and mortality. Cisplatin is a widely used chemotherapeutic agent for treating solid tumors, but the induction of AKI restricts its clinical application. In this study, the effect of cisplatin on the expression of organic ion transporters was investigated through in vivo and in vitro experiments. Targeted metabolomics techniques were used to measure the levels of selected endogenous substances in serum. Transmission electron microscopy was used to observe the microstructure of renal tubular epithelial cells. Our results show that the toxicity of cisplatin on HK-2 cells or HEK-293 cells was time- and dose-dependent. Administration of cisplatin decreased the expression of OAT1/3 and OCT2 and increased the expression of MRP2/4. Mitochondrial damage induced by cisplatin lead to renal tubular epithelial cell injury. In addition, administration of cisplatin resulted in significant changes in endogenous substance levels in serum, including amino acids, carnitine, and fatty acids. These serum amino acids and metabolites (α-aminobutyric acid, proline, and alanine), carnitines (tradecanoylcarnitine, hexanylcarnitine, octanoylcarnitine, 2-methylbutyroylcarnitine, palmitoylcarnitine, and linoleylcarnitine) and fatty acids (9E-tetradecenoic acid) represent endogenous substances with diagnostic potential for cisplatin-induced AKI.