Conclusion
Overall, O-GlcNAcylation regulated glucose metabolism in endometrial cells, and AQP3-mediated compensation provides new insights into the communication between glycolysis and O-GlcNAcylation.
Methods
Different endometrial tissues were detected using immunohistochemistry. Pregnant mouse models were established to verify molecular expression. O-GlcNAc transferase and aquaporin 3 (AQP3) knockdown were used to detect embryo implantation efficiency in vitro and in vivo. Western blotting and immunofluorescence were used to detect protein expression and stability. Dual luciferase reporter assay and chromatin immunoprecipitation (ChIP) were used to verify the binding transcription factor. Glycolysis was detected using bioenergy analyzer, and metabolites were analyzed using isotope 13C-labeled LC-MS. Metabolic-related genes were determined using RNA sequencing.
Results
Activation of endometrial hexosamine biosynthetic pathway (HBP) caused elevated O-GlcNAcylation during the window of implantation, affecting endometrial cell function and embryo implantation. Specifically, elevated O-GlcNAcylation increased glucose uptake via glucose transporter 1 (GLUT1) leading to glucose metabolic flow into the pentose phosphate pathways and HBP, which regulate the metabolic reprogramming of endometrial cells. Furthermore, O-GlcNAcylation mediated the intracellular transport of glycerol to support and compensate for glycolysis through regulation of AQP3. Unexpectedly, elevated AQP3 also increased glucose uptake via GLUT1. These processes maintained higher metabolic requirements for endometrial physiology. Furthermore, the transcription factor SP1 specifically bound to the AQP3 promoter region, and O-GlcNAcylation of SP1 increased its stability and transcriptional regulation of AQP3 which is associated with O-GlcNAcylation of SP1.