title: A new level of regulation in gluconeogenesis: metabolic state modulates the intracellular localization of aldolase B and its interaction with liver fructose-1,6-bisphosphatase.
abstract: Understanding how glucose metabolism is finely regulated at molecular and cellular levels in the liver is critical for knowing its relationship to related pathologies, such as diabetes. In order to gain insight into the regulation of glucose metabolism, we studied the liver-expressed isoforms aldolase B and fructose-1,6-bisphosphatase-1 (FBPase-1), key enzymes in gluconeogenesis, analysing their cellular localization in hepatocytes under different metabolic conditions and their protein-protein interaction in vitro and in vivo. We observed that glucose, insulin, glucagon and adrenaline differentially modulate the intracellular distribution of aldolase B and FBPase-1. Interestingly, the in vitro protein-protein interaction analysis between aldolase B and FBPase-1 showed a specific and regulable interaction between them, whereas aldolase A (muscle isozyme) and FBPase-1 showed no interaction. The affinity of the aldolase B and FBPase-1 complex was modulated by intermediate metabolites, but only in the presence of K(+). We observed a decreased association constant in the presence of adenosine monophosphate, fructose-2,6-bisphosphate, fructose-6-phosphate and inhibitory concentrations of fructose-1,6-bisphosphate. Conversely, the association constant of the complex increased in the presence of dihydroxyacetone phosphate (DHAP) and non-inhibitory concentrations of fructose-1,6-bisphosphate. Notably, in vivo FRET studies confirmed the interaction between aldolase B and FBPase-1. Also, the co-expression of aldolase B and FBPase-1 in cultured cells suggested that FBPase-1 guides the cellular localization of aldolase B. Our results provide further evidence that metabolic conditions modulate aldolase B and FBPase-1 activity at the cellular level through the regulation of their interaction, suggesting that their association confers a catalytic advantage for both enzymes.
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Sciences, Universidad Austral de Chile, Independencia 641,5110566, Valdivia, Chile.
authors.forename: Cristian A
authors.initials: CA
authors.lastname: Droppelmann
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Sciences, Universidad Austral de Chile, Independencia 641,5110566, Valdivia, Chile.
authors.forename: Doris E
authors.initials: DE
authors.lastname: Sáez
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Sciences, Universidad Austral de Chile, Independencia 641,5110566, Valdivia, Chile.
authors.forename: Joel L
authors.initials: JL
authors.lastname: Asenjo
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Sciences, Universidad Austral de Chile, Independencia 641,5110566, Valdivia, Chile.
authors.forename: Alejandro J
authors.initials: AJ
authors.lastname: Yáñez
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain Department of Biochemistry and Molecular Biology, University of Barcelona, Diagonal 643, 08028, Barcelona, Spain CIBER of Diabetes and Metabolic Diseases (CIBERDEM), Instituto de Salud Carlos III, Monforte de Lemos 3-5, 28029 Madrid, Spain.
authors.forename: Mar
authors.initials: M
authors.lastname: García-Rocha
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Sciences, Universidad Austral de Chile, Independencia 641,5110566, Valdivia, Chile.
authors.forename: Ilona I
authors.initials: II
authors.lastname: Concha
authors.affiliation: Institute for Tumor Biology and Experimental Therapy, Georg-Speyer Haus, Paul-Ehrlich-Straβe 42-44, D-60596, Frankfurt, Germany.
authors.forename: Manuel
authors.initials: M
authors.lastname: Grez
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Spain Department of Biochemistry and Molecular Biology, University of Barcelona, Diagonal 643, 08028, Barcelona, Spain CIBER of Diabetes and Metabolic Diseases (CIBERDEM), Instituto de Salud Carlos III, Monforte de Lemos 3-5, 28029 Madrid, Spain.
authors.forename: Joan J
authors.initials: JJ
authors.lastname: Guinovart
authors.affiliation: Department of Biochemistry and Microbiology, Faculty of Sciences, Universidad Austral de Chile, Independencia 641,5110566, Valdivia, Chile jslebe@uach.cl.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Slebe
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004734:Energy Metabolism; D031541:Fluorescence Resonance Energy Transfer; D005455:Fluorescent Antibody Technique; D006597:Fructose-Bisphosphatase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005943:Gluconeogenesis; D006019:Glycolysis; D006367:HeLa Cells; D022781:Hepatocytes / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008297:Male; D018613:Microscopy, Confocal; D008954:Models, Biological; D021381:Protein Transport; D017208:Rats, Wistar; D011993:Recombinant Fusion Proteins / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D006597:Fructose-Bisphosphatase; D005634:Fructose-Bisphosphate Aldolase
keywords: 6-bisphosphatase (FBPase); aldolase B; cell metabolism; cellular localization; enzymes; fructose-1; gluconeogenesis; protein–protein interaction