2102Ep embryonal carcinoma cells have compromised respiration and shifted bioenergetic profile distinct from H9 human embryonic stem cells

Recent studies have shown that cellular bioenergetics may be involved in stem cell differentiation. Considering that during cancerogenesis cells acquire numerous properties of stem cells, it is possible to assume that the energy metabolism in tumorigenic cells might be differently regulated. The aim of this study was to compare the mitochondrial bioenergetic profile of normal pluripotent human embryonic stem cells (hESC) and relatively nullipotent embryonal carcinoma cells (2102Ep cell line). We examined three parameters related to cellular bioenergetics: phosphotransfer system, aerobic glycolysis, and oxygen consumption. Activities and expression levels of main enzymes that facilitate energy transfer were measured. The oxygen consumption rate studies were performed to investigate the respiratory capacity of cells. 2102Ep cells showed a shift in energy distribution towards adenylate kinase network. The total AK activity was almost 3 times higher in 2102Ep cells compared to hESCs (179.85 ± 5.73 vs 64.39 ± 2.55 mU/mg of protein) and the expression of AK2 was significantly higher in these cells, while CK was downregulated. 2102Ep cells displayed reduced levels of oxygen consumption and increased levels of aerobic glycolysis compared to hESCs. The compromised respiration of 2102Ep cells is not the result of increased mitochondrial mass, increased proton leak, and reduced respiratory reserve capacity of the cells or impairment of respiratory chain complexes. Our data showed that the bioenergetic profile of 2102Ep cells clearly distinguishes them from normal hESCs. This should be considered when this cell line is used as a reference, and highlight the importance of further research concerning energy metabolism of stem cells

2102Ep embryonal carcinoma cells have compromised respiration and shifted bioenergetic profile distinct from H9 human embryonic stem cells

Recent studies have shown that cellular bioenergetics may be involved in stem cell differentiation. Considering that during cancerogenesis cells acquire numerous properties of stem cells, it is possible to assume that the energy metabolism in tumorigenic cells might be differently regulated. The aim of this study was to compare the mitochondrial bioenergetic profile of normal pluripotent human embryonic stem cells (hESC) and relatively nullipotent embryonal carcinoma cells (2102Ep cell line). We examined three parameters related to cellular bioenergetics: phosphotransfer system, aerobic glycolysis, and oxygen consumption. Activities and expression levels of main enzymes that facilitate energy transfer were measured. The oxygen consumption rate studies were performed to investigate the respiratory capacity of cells. 2102Ep cells showed a shift in energy distribution towards adenylate kinase network. The total AK activity was almost 3 times higher in 2102Ep cells compared to hESCs (179.85±5.73 vs 64.39±2.55mU/mg of protein) and the expression of AK2 was significantly higher in these cells, while CK was downregulated. 2102Ep cells displayed reduced levels of oxygen consumption and increased levels of aerobic glycolysis compared to hESCs. The compromised respiration of 2102Ep cells is not the result of increased mitochondrial mass, increased proton leak, and reduced respiratory reserve capacity of the cells or impairment of respiratory chain complexes. Our data showed that the bioenergetic profile of 2102Ep cells clearly distinguishes them from normal hESCs. This should be considered when this cell line is used as a reference, and highlight the importance of further research concerning energy metabolism of stem cells

Studies of the role of tubulin beta II isotype in regulation of mitochondrial respiration in intracellular energetic units in cardiac cells.

International audienceThe aim of this study was to investigate the possible role of tubulin βII, a cytoskeletal protein, in regulation of mitochondrial oxidative phosphorylation and energy fluxes in heart cells. This isotype of tubulin is closely associated with mitochondria and co-expressed with mitochondrial creatine kinase (MtCK). It can be rapidly removed by mild proteolytic treatment of permeabilized cardiomyocytes in the absence of stimulatory effect of cytochrome c, that demonstrating the intactness of the outer mitochondrial membrane. Contrary to isolated mitochondria, in permeabilized cardiomyocytes (in situ mitochondria) the addition of pyruvate kinase (PK) and phosphoenolpyruvate (PEP) in the presence of creatine had no effect on the rate of respiration controlled by activated MtCK, showing limited permeability of voltage-dependent anion channel (VDAC) in mitochondrial outer membrane (MOM) for ADP regenerated by MtCK. Under normal conditions, this effect can be considered as one of the most sensitive tests of the intactness of cardiomyocytes and controlled permeability of MOM for adenine nucleotides. However, proteolytic treatment of permeabilized cardiomyocytes with trypsin, by removing mitochondrial βII tubulin, induces high sensitivity of MtCK-regulated respiration to PK-PEP, significantly changes its kinetics and the affinity to exogenous ADP. MtCK coupled to ATP synthasome and to VDAC controlled by tubulin βII provides functional compartmentation of ATP in mitochondria and energy channeling into cytoplasm via phosphotransfer network. Therefore, direct transfer of mitochondrially produced ATP to sites of its utilization is largely avoided under physiological conditions, but may occur in pathology when mitochondria are damaged. This article is part of a Special Issue entitled ''Local Signaling in Myocytes''