Abstract
Ability to adapt to conditions of limited nutrient supply requires a reorganization of the metabolic pathways to balance energy generation and production of biosynthetic intermediates. Several fast-growing cells overexpress the P2X7 receptor (P2X7R) for extracellular ATP. A feature of this receptor is to allow growth in the absence of serum. We show here that transfection of P2X7R allows proliferation of P2X7R-transfected HEK293 (HEK293-P2X7) cells not only in the absence of serum but also in low (4 mM) glucose, and increases lactate output compared with mock-transfected HEK293 (HEK293-mock) cells. In HEK293-P2X7, lactate output is further stimulated upon addition of exogenous ATP or the mitochondrial uncoupler carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP). In the human neuroblastoma cell line ACN, lactate output is also dependent on P2X7R function. P2X7R-expressing cells upregulate (a) the glucose transporter Glut1, (b) the glycolytic enzymes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), (c) phosphofructokinase (PFK), (d) pyruvate kinase M2 (PKM2) and (e) pyruvate dehydrogenase kinase 1 (PDHK1); furthermore, P2X7R expression (a) inhibits pyruvate dehydrogenase (PDH) activity, (b) increases phosphorylated Akt/PKB and hypoxia-inducible factor 1α (HIF-1α) expression and (c) enhances intracellular glycogen stores. In HEK293-P2X7 cells, glucose deprivation increases lactate production, expression of glycolytic enzymes and ph-Akt/PKB level. These data show that the P2X7R has an intrinsic ability to reprogram cell metabolism to meet the needs imposed by adverse environmental conditions.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3-Phosphoinositide-Dependent Protein Kinases
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Adenosine Triphosphate / pharmacology
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Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / chemistry
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Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / pharmacology
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Cell Line, Tumor
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Glucose Transporter Type 1 / genetics
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Glucose Transporter Type 1 / metabolism
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Glyceraldehyde-3-Phosphate Dehydrogenases / genetics
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Glyceraldehyde-3-Phosphate Dehydrogenases / metabolism
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Glycolysis* / drug effects
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HEK293 Cells
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Humans
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Hypoxia-Inducible Factor 1, alpha Subunit / genetics
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Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
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Ketone Oxidoreductases / genetics
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Ketone Oxidoreductases / metabolism
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Lactic Acid / metabolism
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Phosphofructokinases / genetics
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Phosphofructokinases / metabolism
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins c-akt / genetics
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Proto-Oncogene Proteins c-akt / metabolism
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Pyruvate Dehydrogenase Acetyl-Transferring Kinase
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Pyruvate Kinase / genetics
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Pyruvate Kinase / metabolism
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Receptors, Purinergic P2X7 / metabolism*
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Transfection
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Up-Regulation
Substances
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Glucose Transporter Type 1
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Hypoxia-Inducible Factor 1, alpha Subunit
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Pyruvate Dehydrogenase Acetyl-Transferring Kinase
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Receptors, Purinergic P2X7
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Lactic Acid
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Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
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Adenosine Triphosphate
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Ketone Oxidoreductases
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Glyceraldehyde-3-Phosphate Dehydrogenases
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pyruvate dehydrogenase (NADP+)
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Phosphofructokinases
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Pyruvate Kinase
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3-Phosphoinositide-Dependent Protein Kinases
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Protein Serine-Threonine Kinases
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Proto-Oncogene Proteins c-akt