title: Two ubiquitin ligases, APC/C-Cdh1 and SKP1-CUL1-F (SCF)-beta-TrCP, sequentially regulate glycolysis during the cell cycle.
abstract: During cell proliferation, the abundance of the glycolysis-promoting enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, isoform 3 (PFKFB3), is controlled by the ubiquitin ligase APC/C-Cdh1 via a KEN box. We now demonstrate in synchronized HeLa cells that PFKFB3, which appears in mid-to-late G1, is essential for cell division because its silencing prevents progression into S phase. In cells arrested by glucose deprivation, progression into S phase after replacement of glucose occurs only when PFKFB3 is present or is substituted by the downstream glycolytic enzyme 6-phosphofructo-1-kinase. PFKFB3 ceases to be detectable during late G1/S despite the absence of Cdh1; this disappearance is prevented by proteasomal inhibition. PFKFB3 contains a DSG box and is therefore a potential substrate for SCF-β-TrCP, a ubiquitin ligase active during S phase. In synchronized HeLa cells transfected with PFKFB3 mutated in the KEN box, the DSG box, or both, we established the breakdown routes of the enzyme at different stages of the cell cycle and the point at which glycolysis is enhanced. Thus, the presence of PFKFB3 is tightly controlled to ensure the up-regulation of glycolysis at a specific point in G1. We suggest that this up-regulation of glycolysis and its associated events represent the nutrient-sensitive restriction point in mammalian cells.
authors.affiliation: Wolfson Institute for Biomedical Research and Research Department of Pathology, University College London, London WC1E 6BT, United Kingdom.
authors.forename: Slavica
authors.initials: S
authors.lastname: Tudzarova
authors.forename: Sergio L
authors.initials: SL
authors.lastname: Colombo
authors.forename: Kai
authors.initials: K
authors.lastname: Stoeber
authors.forename: Saul
authors.initials: S
authors.lastname: Carcamo
authors.forename: Gareth H
authors.initials: GH
authors.lastname: Williams
authors.forename: Salvador
authors.initials: S
authors.lastname: Moncada
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D002453:Cell Cycle / Q000502:physiology*; D049109:Cell Proliferation; D004795:Enzyme Stability; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008969:Molecular Sequence Data; D025481:Phosphofructokinase-2 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*
chemical_list: D019344:Lactic Acid; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044843:SKP Cullin F-Box Protein Ligases; C107345:PFKFB3 protein, human; D025481:Phosphofructokinase-2; D005947:Glucose