title: Growth factors stimulate the activity of key glycolytic enzymes in isolated digestive gland cells from mussels (Mytilus galloprovincialis Lam.) through tyrosine kinase mediated signal transduction.
abstract: Digestive gland cells isolated from mussels (Mytilus) have previously been demonstrated to respond to mammalian EGF with a cytosolic Ca(2+) transient and stimulated DNA synthesis; both responses were mediated by activation of tyrosine kinase receptors. The present study examines the mechanisms involved in further signal progression and possible targets of phosphorylation/dephosphorylation processes. The effects of EGF, IGF-I, and insulin on the activity of two key glycolytic enzymes PFK (phosphofructokinase) and PK (pyruvate kinase) were evaluated. All the peptides tested induced a transient and dose-dependent stimulation of the activity of both PFK and PK, which involved activation of MAPKs. Quantitative immunoelectron microscopy, utilizing monoclonal anti-phosphotyrosine antibodies, revealed that EGF induced a transient increase in tyrosine phosphorylation. The results demonstrate that, in marine invertebrate cells, activation of tyrosine kinase membrane receptors by growth factors triggers signal transduction pathways involving a phosphorylative cascade similar to that of mammalian cells. Moreover, these data suggest that, in mussel cells, growth factors may play a physiological role in the in vivo regulation of glucose metabolism by modulating, through reversible phosphorylation, the activity of key glycolytic enzymes.
authors.affiliation: Istituto di Scienze Fisiologiche, Universit¿a di Urbino, Loc. Crocicchia.
authors.forename: L
authors.initials: L
authors.lastname: Canesi
authors.forename: C
authors.initials: C
authors.lastname: Ciacci
authors.forename: M
authors.initials: M
authors.lastname: Betti
authors.forename: M
authors.initials: M
authors.lastname: Malatesta
authors.forename: G
authors.initials: G
authors.lastname: Gazzanelli
authors.forename: G
authors.initials: G
authors.lastname: Gallo
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D049872:Bivalvia / Q000201:enzymology*; D004064:Digestive System / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D006019:Glycolysis / Q000187:drug effects*; D006133:Growth Substances / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D016253:Microscopy, Immunoelectron; D010732:Phosphofructokinase-1 / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000276:immunology; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000911:Antibodies, Monoclonal; D006133:Growth Substances; D007328:Insulin; D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D007334:Insulin-Like Growth Factor I; D010732:Phosphofructokinase-1; D011770:Pyruvate Kinase; D011505:Protein-Tyrosine Kinases