title: Differential contribution of key metabolic substrates and cellular oxygen in HIF signalling.
abstract: Changes in availability and utilisation of O2 and metabolic substrates are common in ischemia and cancer. We examined effects of substrate deprivation on HIF signalling in PC12 cells exposed to different atmospheric O2. Upon 2-4h moderate hypoxia, HIF-α protein levels were dictated by the availability of glutamine and glucose, essential for deep cell deoxygenation and glycolytic ATP flux. Nuclear accumulation of HIF-1α dramatically decreased upon inhibition of glutaminolysis or glutamine deprivation. Elevation of HIF-2α levels was transcription-independent and associated with the activation of Akt and Erk1/2. Upon 2h anoxia, HIF-2α levels strongly correlated with cellular ATP, produced exclusively via glycolysis. Without glucose, HIF signalling was suppressed, giving way to other regulators of cell adaptation to energy crisis, e.g. AMPK. Consequently, viability of cells deprived of O2 and glucose decreased upon inhibition of AMPK with dorsomorphin. The capacity of cells to accumulate HIF-2α decreased after 24h glucose deprivation. This effect, associated with increased AMPKα phosphorylation, was sensitive to dorsomorphin. In chronically hypoxic cells, glutamine played no major role in HIF-2α accumulation, which became mainly glucose-dependent. Overall, the availability of O2 and metabolic substrates intricately regulates HIF signalling by affecting cell oxygenation, ATP levels and pathways involved in production of HIF-α.
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland. Electronic address: a.zhdanov@ucc.ie.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Zhdanov
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland.
authors.forename: Alicia H C
authors.initials: AH
authors.lastname: Waters
authors.affiliation: Alimentary Pharmabiotic Centre, University College Cork, Bioscience Institute, Western Road, Cork, Ireland.
authors.forename: Anna V
authors.initials: AV
authors.lastname: Golubeva
authors.affiliation: School of Biochemistry and Cell Biology, University College Cork, Cavanagh Pharmacy Building, College Road, Cork, Ireland.
authors.forename: Dmitri B
authors.initials: DB
authors.lastname: Papkovsky
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D015687:Cell Hypoxia; D005947:Glucose / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D016716:PC12 Cells; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D000099162:Endothelial PAS Domain-Containing Protein 1
chemical_list: D055372:AMP-Activated Protein Kinases; D000255:Adenosine Triphosphate; D051792:Basic Helix-Loop-Helix Proteins; D005947:Glucose; D005973:Glutamine; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010100:Oxygen; D051057:Proto-Oncogene Proteins c-akt; D011720:Pyrazoles; D011743:Pyrimidines; D000099162:Endothelial PAS Domain-Containing Protein 1; C516138:dorsomorphin
keywords: Cancer cell; Cellular oxygen; Glutaminolysis; Glycolysis; HIF signalling; Metabolic substrates