Dataset Information

Requirement of hepatic pyruvate carboxylase during fasting, high fat and ketogenic diet

ABSTRACT: Pyruvate has two major fates upon entry into mitochondria, the oxidative decarboxylation to acetyl-CoA or the biotin-dependent carboxylation to oxaloacetate via pyruvate carboxylase (Pcx). Here we have generated mice with a liver specific knockout of pyruvate carboxylase (PcxL-/-) to understand the role of Pcx in hepatic mitochondrial metabolism under disparate physiological states. PcxL-/- mice exhibited a deficit in hepatic gluconeogenesis as expected but were able to maintain systemic euglycemia following a 24hr fast and enhanced ketogenesis. Feeding a high fat diet to PcxL-/- mice resulted in animals that were resistant to glucose intolerance without affecting body weight. However, PcxL-/- mice fed a ketogenic diet for 1 week became severely hypoglycemic, demonstrating a requirement for hepatic Pcx for long term glycemia under carbohydrate limited diets. Loss of Pcx was associated with an induction of protein acetylation in PcxL-/- mice regardless of physiologic state. Furthermore, liver acetyl-proteomics revealed a biased induction in mitochondrial lysine acetylation. These data show that Pcx is important for maintaining the proper balance of pyruvate metabolism between oxidative and anaplerotic pathways.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Liver

SUBMITTER: Michael Wolfgang

LAB HEAD: Michael Wolfgang

PROVIDER: PXD032028 | Pride | 2022-10-31

REPOSITORIES: Pride

ACCESS DATA

Similar Datasets

Project description:Hepatic fat accumulation has been widely associated with diabetes and hepatocellular carcinoma (HCC). Here, we aim to characterize the metabolic response that high fat availability elicits in livers prior to development of these diseases. We find that, after a short term on high fat diet, otherwise healthy mice show elevated hepatic glucose metabolization, activated glucose uptake, glycolysis and glucose contribution to serine as well as elevated pyruvate carboxylase activity compared to control diet mice. To understand other changes in the liver tissue after high fat diet exposure, we conducted untargeted transcriptomics and proteomics. This glucose phenotype occurred independent from transcriptional or proteomic programming, which identified increased peroxisomal and lipid metabolism pathways. Interestingly, we observe that high fat diet fed mice exhibit an increased lactate production when challenged with glucose. This trait seems to find a parallel in a human cohort, where we observe a correlation between waist circumference and lactate secretion after an oral glucose bolus across healthy individuals. In an in vitro model of hepatoma cells, we found physiologically relevant palmitate exposure stimulated production of reactive oxygen species (ROS) and glucose uptake, a similar glycolytic phenotype to the in vivo study. This effect is inhibited upon interference with peroxisomal lipid metabolism and ROS production. Furthermore, we find that with exposure to an HCC-inducing hepatic carcinogen, continuation of high fat diet enhances the formation of HCC (100% with resectable tumors) as compared to control (50% with resectable tumors) in mice. However, regardless of the dietary background, all murine tumors showed similar alterations in glucose metabolism compared to those identified in fat exposed non-transformed mouse livers. Further, the presence of tumors in high fat diet exposed mice normalized glucose tolerance. Lipidomics analysis of tumor tissue and liver tissue from high fat diet exposed mice identified tumor tissue enrichment of diacylglycerol (DG) and phosphatidylcholine (PC) species. Some of these species were also increased in high fat diet liver tissue compared to control diet liver tissue. These findings suggest that fat can induce similar metabolic changes in non-transformed liver cells than found in HCC, and that peroxisomal metabolism of lipids may be a factor in driving a glycolytic metabolism In conclusion, we show that normal, non-transformed livers respond to fat by inducing glucose metabolism.

Dataset Information

Requirement of hepatic pyruvate carboxylase during fasting, high fat and ketogenic diet

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure