Compensation Response to Hepatic Gluconeogenesis via β-Hydroxybutyrylation of FBP1 and PCK1 in Dairy Cows

Abstract

Perinatal cows are often in a state of negative energy balance (NEB), and hepatic gluconeogenesis is an important energy source in ruminants. NEB can lead to metabolic disorders such as ketosis. β-Hydroxybutyrate (BHB) is a major ketone body that acts as an energy substrate; however, its role and mechanism in hepatic gluconeogenesis in perinatal cows are unclear. The aim of this study was to investigate the compensatory effects of BHB in hepatic gluconeogenesis in dairy cows, particularly its effect on fructose 1,6-bisphosphatase 1 (FBP1) and phosphoenolpyruvate carboxykinase 1 (PCK1), which are key rate-limiting enzymes in gluconeogenesis. We performed Kbhb proteomic analysis of liver tissue samples from perinatal cows and found a significant enrichment of the gluconeogenic pathway. When bovine hepatocytes were treated with different concentrations of BHB, there was a significant increase in cellular glucose production and FBP1/PCK1 activity. With regard to the underlying mechanisms, the findings implied that Kbhb of FBP1/PCK1 may occur in a BHB concentration- and time-dependent manner. Furthermore, Kbhb of FBP1/PCK1 was found to be regulated by histone acetyltransferase p300 (p300) and histone deacetylase (HDACs). Mass spectrometry analysis revealed that Kbhb occurred at lysine (K) 43 of FBP1 and K191 of PCK1. In conclusion, our results demonstrate that the compensatory effects of BHB induced an increase in the enzymatic activity of FBP1 and PCK1 through Kbhb modification at the K43 site of FBP1 and the K191 site of PCK1; in turn, it enhances the hepatic gluconeogenesis of cows to certain BHB concentrations.