title: PFKFB3 activation in cancer cells by the p38/MK2 pathway in response to stress stimuli.
abstract: PFK-2/FBPase-2 (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase) catalyses the synthesis and degradation of Fru-2,6-P2 (fructose 2,6-bisphosphate), a key modulator of glycolysis and gluconeogenesis. The PFKFB3 gene is involved in cell proliferation owing to its role in carbohydrate metabolism. In the present study we analysed the mechanism of regulation of PFKFB3 as an immediate early gene controlled by stress stimuli that activates the p38/MK2 [MAPK (mitogen-activated protein kinase)-activated protein kinase 2] pathway. We report that exposure of HeLa and T98G cells to different stress stimuli (NaCl, H2O2, UV radiation and anisomycin) leads to a rapid increase (15-30 min) in PFKFB3 mRNA levels. The use of specific inhibitors in combination with MK2-deficient cells implicate control by the protein kinase MK2. Transient transfection of HeLa cells with deleted gene promoter constructs allowed us to identify an SRE (serum-response element) to which SRF (serum-response factor) binds and thus transactivates PFKFB3 gene transcription. Direct binding of phospho-SRF to the SRE sequence (-918 nt) was confirmed by ChIP (chromatin immunoprecipiation) assays. Moreover, PFKFB3 isoenzyme phosphorylation at Ser461 by MK2 increases PFK-2 activity. Taken together, the results of the present study suggest a multimodal mechanism of stress stimuli affecting PFKFB3 transcriptional regulation and kinase activation by protein phosphorylation, resulting in an increase in Fru-2,6-P2 concentration and stimulation of glycolysis in cancer cells.
authors.affiliation: Departament de Ciències Fisiològiques II, IDIBELL, Campus de Ciències de la Salut, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona E-08907, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Novellasdemunt
authors.forename: Laurent
authors.initials: L
authors.lastname: Bultot
authors.forename: Anna
authors.initials: A
authors.lastname: Manzano
authors.forename: Francesc
authors.initials: F
authors.lastname: Ventura
authors.forename: Jose Luis
authors.initials: JL
authors.lastname: Rosa
authors.forename: Didier
authors.initials: D
authors.lastname: Vertommen
authors.forename: Mark H
authors.initials: MH
authors.lastname: Rider
authors.forename: Àurea
authors.initials: À
authors.lastname: Navarro-Sabate
authors.forename: Ramon
authors.initials: R
authors.lastname: Bartrons
mesh_terms: D000595:Amino Acid Sequence; D004789:Enzyme Activation / Q000502:physiology; D006019:Glycolysis / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009369:Neoplasms / Q000737:chemistry / Q000235:genetics / Q000473:pathology; D018384:Oxidative Stress / Q000235:genetics; D025481:Phosphofructokinase-2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D048051:p38 Mitogen-Activated Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*
chemical_list: C107345:PFKFB3 protein, human; D025481:Phosphofructokinase-2; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases