title: Activation of glucose transport during simulated ischemia in H9c2 cardiac myoblasts is mediated by protein kinase C isoforms.
abstract: Glucose transport into cells may be regulated by a variety of conditions, including ischemia. We investigated whether some enzymes frequently involved in the metabolic adaptation to ischemia are also required for glucose transport activation. Ischemia was simulated by incubating during 3 h H9c2 cardiomyoblasts in a serum- and glucose-free medium in hypoxia. Under these conditions 2-deoxy-d-[2,6-(3)H]-glucose uptake was increased (57% above control levels, p<0.0001) consistently with GLUT1 and GLUT4 translocation to sarcolemma. Tyrosine kinases inhibition via tyrphostin had no effect on glucose transport up-regulation induced by simulated ischemia. On the other hand, chelerythrine, a broad range inhibitor of protein kinase C isoforms, and rottlerin, an inhibitor of protein kinase C delta, completely prevented the stimulation of the transport rate. A lower activation of hexose uptake (19%, p<0.001) followed also treatment with Gö6976, an inhibitor of conventional protein kinases C. Finally, PD98059-mediated inhibition of the phosphorylation of ERK 1/2, a downstream mitogen-activated protein kinase (MAPK), only partially reduced the activation of glucose transport induced by simulated ischemia (31%, p<0.01), while SB203580, an inhibitor of p38 MAPK, did not exert any effect. These results indicate that stimulation of protein kinase C delta is strongly related to the up-regulation of glucose transport induced by simulated ischemia in cultured cardiomyoblasts and that conventional protein kinases C and ERK 1/2 are partially involved in the signalling pathways mediating this process.
authors.affiliation: Department of Biochemistry "G. Moruzzi", University of Bologna, Via Irnerio 48, 40126 Bologna, Italy. agnetti@biocfarm.unibo.it
authors.forename: Giulio
authors.initials: G
authors.lastname: Agnetti
authors.forename: Tullia
authors.initials: T
authors.lastname: Maraldi
authors.forename: Diana
authors.initials: D
authors.lastname: Fiorentini
authors.forename: Emanuele
authors.initials: E
authors.lastname: Giordano
authors.forename: Cecilia
authors.initials: C
authors.lastname: Prata
authors.forename: Gabriele
authors.initials: G
authors.lastname: Hakim
authors.forename: Claudio
authors.initials: C
authors.lastname: Muscari
authors.forename: Carlo
authors.initials: C
authors.lastname: Guarnieri
authors.forename: Claudio Marcello
authors.initials: CM
authors.lastname: Caldarera
mesh_terms: D000818:Animals; D001692:Biological Transport; D015687:Cell Hypoxia; D002460:Cell Line; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D008954:Models, Biological; D032386:Myoblasts, Cardiac / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D017202:Myocardial Ischemia / Q000201:enzymology / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats
chemical_list: D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D011493:Protein Kinase C; D005947:Glucose