Glucagon Promotes Gluconeogenesis through the GCGR/PKA/CREB/PGC-1α Pathway in Hepatocytes of the Japanese Flounder Paralichthys olivaceus

The Neurometabolic Function of the Dopamine-Aminotransferase System

BACKGROUND/OBJECTIVES

The neurometabolic function is controlled by a complex multi-level physiological system that includes neurochemical, hormonal, immunological, sensory, and metabolic components. Functional disorders of monoamine systems are often detected in clinical practice together with metabolic dysfunctions. An important part of the mentioned pathological conditions are associated with disturbances in protein metabolism, some of the most important biomarkers which are aminotransferases and transcription factors that regulate and direct the most important metabolic reactions. Another important part of energy metabolism is the dopamine-mediated regulation of protein metabolism.

METHODS

The review describes research results into the dopamine-mediated mechanism of metabolic regulation in humans and animals. Particular attention is paid to the neurometabolic mechanisms of protein metabolism.

RESULTS

The dopamine-aminotransferase system of the energy metabolism regulation is a separate, independent, regulatory and diagnostically significant biochemical pathway controlled by the hormonal system, the key hormone is cortisol, the key neurotransmitter is dopamine, the key transcription factor is CREB, and the key regulatory enzymes are alanine aminotransferase, aspartate aminotransferase, and tyrosine aminotransferase.

CONCLUSIONS

This review presents an original study describing the discovery of a new regulatory mechanism for neurometabolic physiological function in humans and animals. A key part of this mechanism is the dopamine-aminotransferase system.

Small molecules targeting selective PCK1 and PGC-1α lysine acetylation cause anti-diabetic action through increased lactate oxidation

Small molecules selectively inducing peroxisome proliferator-activated receptor-gamma coactivator (PGC)-1α acetylation and inhibiting glucagon-dependent gluconeogenesis causing anti-diabetic effects have been identified. However, how these small molecules selectively suppress the conversion of gluconeogenic metabolites into glucose without interfering with lipogenesis is unknown. Here, we show that a small molecule SR18292 inhibits hepatic glucose production by increasing lactate and glucose oxidation. SR18292 increases phosphoenolpyruvate carboxykinase 1 (PCK1) acetylation, which reverses its gluconeogenic reaction and favors oxaloacetate (OAA) synthesis from phosphoenolpyruvate. PCK1 reverse catalytic reaction induced by SR18292 supplies OAA to tricarboxylic acid (TCA) cycle and is required for increasing glucose and lactate oxidation and suppressing gluconeogenesis. Acetylation mimetic mutant PCK1 K91Q favors anaplerotic reaction and mimics the metabolic effects of SR18292 in hepatocytes. Liver-specific expression of PCK1 K91Q mutant ameliorates hyperglycemia in obese mice. Thus, SR18292 blocks gluconeogenesis by enhancing gluconeogenic substrate oxidation through PCK1 lysine acetylation, supporting the anti-diabetic effects of these small molecules.

Preliminary analysis of pathways and their implications during salinity stress in abalone

Transcriptome sequencing has offered immense opportunities to study non-model organisms. Abalone is an important marine mollusk that encounters harsh environmental conditions in its natural habitat and under aquaculture conditions; hence, research that increases molecular information to understand abalone physiology and stress response is noteworthy. Accordingly, the study used transcriptome sequencing of the gill tissues of abalone exposed to low salinity stress. The aim is to explore some enriched pathways during salinity stress and the crosstalk and functions of the genes involved in the candidate biological processes for future further analysis of their expression patterns. The data suggest that abalone genes such as YAP/TAZ, Myc, Nkd, and Axin (involved in the Hippo signaling pathway) and PI3K/Akt, SHC, and RTK (involved in the Ras signaling pathways) might mediate growth and development. Thus, deregulation of the Hippo and Ras pathways by salinity stress could be a possible mechanism by which unfavorable salinities influence growth in abalone. Furthermore, PEPCK, GYS, and PLC genes (mediating the Glucagon signaling pathway) might be necessary for glucose homeostasis, reproduction, and abalone meat sensory qualities; hence, a need to investigate how they might be influenced by environmental stress. Genes such as MYD88, IRAK1/4, JNK, AP-1, and TRAF6 (mediating the MAPK signaling pathway) could be useful in understanding abalone's innate immune response to environmental stresses. Finally, the aminoacyl-tRNA biosynthesis pathway hints at the mechanism by which new raw materials for protein biosynthesis are mobilized for physiological processes and how abalone might respond to this process during salinity stress. Low salinity clearly regulated genes in these pathways in a time-dependent manner, as hinted by the heat maps. In the future, qRT-PCR verification and in-depth study of the various genes and proteins discussed would provide enormous molecular information resources for the abalone biology.