Acute kidney injury (AKI) is a common clinically critical syndrome in hospitalized patients with high morbidity and mortality. At present, the mechanism of AKI has not been fully elucidated, and no therapeutic drugs exist. As known, glycolytic product lactate is a key metabolite in physiological and pathological processes. The kidney is an important gluconeogenic organ, where lactate is the primary substrate of renal gluconeogenesis in physiological conditions. During AKI, altered glycolysis and gluconeogenesis in kidneys significantly disturb the lactate metabolic balance, which exert impacts on the severity and prognosis of AKI. Additionally, lactate-derived posttranslational modification, namely lactylation, is novel to AKI as it could regulate gene transcription of metabolic enzymes involved in glycolysis or Warburg effect. Protein lactylation widely exists in human tissues and may severely affect non-histone functions. Moreover, the strategies of intervening lactate metabolic pathways are expected to bring a new dawn for the treatment of AKI. This review focused on renal lactate metabolism, especially in proximal renal tubules after AKI, and updated recent advances of lactylation modification, which may help to explore potential therapeutic targets against AKI.
Humans ; Acute Kidney Injury/metabolism* ; Lactic Acid/metabolism* ; Animals ; Glycolysis/physiology* ; Gluconeogenesis/physiology* ; Kidney/metabolism*

BACKGROUND: Gluconeogenesis is a critical metabolic pathway for maintaining glucose homeostasis, and its dysregulation can lead to glycometabolic disorders. This study aimed to identify hub biomarkers of these disorders to provide a theoretical foundation for enhancing diagnosis and treatment. METHODS: Gene expression profiles from liver tissues of three well-characterized gluconeogenesis mouse models were analyzed to identify commonly differentially expressed genes (DEGs). Weighted gene co-expression network analysis (WGCNA), machine learning techniques, and diagnostic tests on transcriptome data from publicly available datasets of type 2 diabetes mellitus (T2DM) patients were employed to assess the clinical relevance of these DEGs. Subsequently, we identified hub biomarkers associated with gluconeogenesis-related glycometabolic disorders, investigated potential correlations with immune cell types, and validated expression using quantitative polymerase chain reaction in the mouse models. RESULTS: Only a few common DEGs were observed in gluconeogenesis-related glycometabolic disorders across different contributing factors. However, these DEGs were consistently associated with cytokine regulation and oxidative stress (OS). Enrichment analysis highlighted significant alterations in terms related to cytokines and OS. Importantly, osteomodulin ( OMD ), apolipoprotein A4 ( APOA4 ), and insulin like growth factor binding protein 6 ( IGFBP6 ) were identified with potential clinical significance in T2DM patients. These genes demonstrated robust diagnostic performance in T2DM cohorts and were positively correlated with resting dendritic cells. CONCLUSIONS Gluconeogenesis-related glycometabolic disorders exhibit considerable heterogeneity, yet changes in cytokine regulation and OS are universally present. OMD , APOA4 , and IGFBP6  may serve as hub biomarkers for gluconeogenesis-related glycometabolic disorders.
Machine Learning ; Humans ; Computational Biology/methods* ; Biomarkers/metabolism* ; Diabetes Mellitus, Type 2/genetics* ; Animals ; Mice ; Gluconeogenesis/physiology* ; Gene Expression Profiling ; Transcriptome/genetics* ; Gene Regulatory Networks/genetics* ; Clinical Relevance

Six transmembrane protein of prostate 2 (STAMP2) plays a key role in linking inflammatory and diet-derived signals to systemic metabolism. STAMP2 is induced by nutrients/feeding as well as by cytokines such as TNFalpha, IL-1beta, and IL-6. Here, we demonstrated that STAMP2 protein physically interacts with and decreases the stability of hepatitis B virus X protein (HBx), thereby counteracting HBx-induced hepatic lipid accumulation and insulin resistance. STAMP2 suppressed the HBx-mediated transcription of lipogenic and adipogenic genes. Furthermore, STAMP2 prevented HBx-induced degradation of IRS1 protein, which mediates hepatic insulin signaling, as well as restored insulin-mediated inhibition of gluconeogenic enzyme expression, which are gluconeogenic genes. We also demonstrated reciprocal expression of HBx and STAMP2 in HBx transgenic mice. These results suggest that hepatic STAMP2 antagonizes HBx-mediated hepatocyte dysfunction, thereby protecting hepatocytes from HBV gene expression.
Animals ; Female ; Gene Expression ; Gluconeogenesis/genetics ; Hep G2 Cells ; Humans ; Insulin/pharmacology/physiology ; Insulin Receptor Substrate Proteins/genetics/metabolism ; Insulin Resistance ; *Lipid Metabolism ; Liver/*metabolism/physiopathology ; Male ; Membrane Proteins/metabolism/*physiology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred CBA ; Mice, Transgenic ; Oxidoreductases/metabolism/*physiology ; Phosphorylation ; Protein Binding ; Protein Processing, Post-Translational ; Proteolysis ; Receptor, Insulin/metabolism ; Trans-Activators/*physiology ; Transcriptional Activation

OBJECTIVETo introduce a safe and specific approach of (13)C magnetic resonance spectrum ((13)C MRS) spectroscopy and investigate the alterations in hepatic anabolism.

METHODSRelative anaplerotic, pyruvate recycling and gluconeogenic fluxes were measured by (13)C MRS isotopomer analysis of blood glucose from rats with 40% body surface area burn injury, and from rats exposed to sham injury. A short chain fatty acid, [U (13)C] propionate which was avidly extracted by the liver, was infused intravenously to deliver (13)C into the citric acid cycle. Proton-decoupled (13)C MRS of deproteinized plasma or extracts of the freeze-clamped liver were used to determine the distribution of (13)C in blood or hepatic glucose.

RESULTSThere was no difference in the multiplets detected in the glucose carbon-2 anomer from blood or liver after 45 or 60 minutes of the infusion of the propionate, indicating that steady-state isotopic conditions were achieved. Gluconeogenesis relative to citric acid cycle flux was not altered by burn injury; in both sham and burn groups the rate of glucose production was about equal to flux through citrate synthase. In the sham group of animals, the rate of entry of carbon skeletons into the citric acid cycle was about 4 times than that in the burn group. Similarly, flux through pyruvate kinase (again relative to citrate synthase) was significantly increased after the burn injury.

CONCLUSIONSSince results from analysis of the blood glucose are the same as that of the hepatic glucose, (13)C distribution in the glucose and hepatic metabolism can be assessed based on the (13)C MRS analysis of the blood glucose.

Animals ; Blood Glucose ; analysis ; Burns ; complications ; Carbon Isotopes ; Citric Acid Cycle ; physiology ; Disease Models, Animal ; Gluconeogenesis ; physiology ; Liver Diseases ; etiology ; pathology ; Liver Function Tests ; Magnetic Resonance Spectroscopy ; methods ; Male ; Probability ; Radiographic Image Enhancement ; Rats ; Rats, Sprague-Dawley ; Reference Values ; Sensitivity and Specificity