Protein & Cell | Single cell analysis reveals that oxidative phosphorylation of generates embryonic stem cells is the main energy source and couples the hexosamine synthesis pathway to regulate pluripotency
mitochondrial oxidative phosphorylation (oxidative Phosphorylation, OXPHOS) and glycolysis (glycolysis) are the two main ways for organisms to obtain ATP, and their intermediate products play important regulatory functions in many cellular life activities. Increasing evidence shows that material and energy metabolism play a critical role in cell fate determination. Compared with somatic cells, embryonic stem cells (Embryonic Stem Cell, ESC) have a short division cycle and a fast proliferation rate, suggesting that ESCs have unique metabolic characteristics to maintain their homeostasis of self-renewal and rapid proliferation. Because the structure of ESC mitochondria is spherical and has fewer ridges, it has always been considered an "immature" state. Compared with other somatic cells, ESCs have high levels of glycolysis and low levels of oxidative phosphorylation. Therefore, the traditional view in the field is that ESCs mainly rely on glycolysis for energy, and mitochondria oxidative phosphorylation has a limited energy supply [1-7] . However, the size of of different types of cells, the composition of organelles, and the content of mitochondria themselves vary widely. Just comparing the overall level between cell types cannot objectively reflect the functional differences in the mitochondria themselves within the cells. In recent years, research has gradually discovered that mitochondria play an irreplaceable role in the maintenance of pluripotency. For example, "naïve (original state) ESCs" at an earlier stage of development are better than "prime (original state) ESCs" have higher oxidative phosphorylation levels[8-10]; mitochondrial homeostasis regulated by high autophagy flow is a key factor to ensure the efficiency of somatic cell reprogramming and maintain the stemness of pluripotent stem cells[11,12].
Recently, the research group of Zhao Tongbiao of the Institute of Zoology, Chinese Academy of Sciences, the research group of Chang Zhijie of Tsinghua University School of Medicine, and the research group of Li Dong of the Institute of Biophysics, Chinese Academy of Sciences, published online in the journal Protein & Cell titled Oxidative Phosphorylation safeguards pluripotency via UDP-N-acetylglucosamine Papers on . This work found that mitochondria in embryonic stem cells have efficient ATP production capacity, and oxidative phosphorylation is the main energy production method of pluripotent stem cells; oxidative phosphorylation is coupled to the hexosamine synthesis pathway, and regulates the self-renewal and multi-directional differentiation potential of pluripotent stem cells through the aminoacetyl glycosylation modification of pluripotency factors.
researchers measured original state ESC, originating state ESC, through SIM-3D imaging technology. The cell volume of neural stem cells, embryonic fiber cells , cardiomyocytes and the total volume of mitochondria in single cells were combined with the mitochondrial protein content of various types of cells. Using unit cell number, unit cell protein mass, unit mitochondrial volume, and unit mitochondrial protein mass as rulers, compared the energy supply of oxidative phosphorylation in the above five types of cells. The research results found that the oxidative phosphorylation capacity of mitochondria of Naïve ESC was significantly higher than that of mitochondria of other types of cells under the same volume or mass conditions (original ESC, neural stem cells, embryonic fibroblasts, cardiomyocytes) . Analysis of oxidative phosphorylation and glycolysis energy supply within a single cell showed that oxidative phosphorylation provided approximately 70% of the energy in Naïve ESC cells; in Prime ESC cells, oxidative phosphorylation provided approximately 50% of the energy.
Further metabolomic research showed that inhibiting oxidative phosphorylation caused a significant decrease in the content of UDP-GlcNAc in embryonic stem cells and a decrease in the glycosylated level of the intracellular protein .Among them, the glycosylation levels of pluripotency proteins OCT4 and SOX2 were significantly reduced within 0.5 hours after oxidative phosphorylation was inhibited, and the expression of pluripotency proteins was significantly reduced after 3 hours. By studying the response of the inner cell mass of in blastocysts to oxidative phosphorylation inhibition and GlcNAc anaplerosis, we demonstrated the importance of the oxidative phosphorylation-coupled hexosamine synthesis pathway during early embryonic development in vivo.
This study proposed a new view that mitochondria in embryonic stem cells are in a "hyperactive" state, discovered that oxidative phosphorylation is the main energy production method of pluripotent stem cells, and revealed that oxidative phosphorylation, while providing the main energy for pluripotent stem cells, regulates the expression of pluripotent proteins through glycosylation modification to regulate the stemness of pluripotent stem cells. The study also suggests that cells at an earlier stage of development have higher mitochondrial activity.
This work was completed by the team of researcher Zhao Tongbiao from the Institute of Zoology, Chinese Academy of Sciences, the team of Professor Chang Zhijie from Tsinghua University, and the team of researcher Li Dong from the Institute of Biophysics, Chinese Academy of Sciences. Zhao Tongbiao is the corresponding author of this paper. Dr. Cao Jiani from the Institute of Zoology, Chinese Academy of Sciences, and Li Meng, a doctoral candidate at Tsinghua University, are the co-first authors of the paper.
Original link:
https://doi.org/10.1093/procel/pwac009
Plate maker: Eleven
