title: Protein kinase C signaling transduces endorphin-primed cardiogenesis in GTR1 embryonic stem cells.
abstract: The prodynorphin gene and its product, dynorphin B, have been found to promote cardiogenesis in embryonic cells by inducing the expression of GATA-4 and Nkx-2.5, two transcription factor-encoding genes essential for cardiogenesis. The molecular mechanism(s) underlying endorphin-induced cardiogenesis remain unknown. In the present study, we found that GTR1 embryonic stem (ES) cells expressed cell surface kappa opioid receptors, as well as protein kinase C (PKC)-alpha, -beta1, -beta2, -delta, -epsilon, and -zeta. Cardiac differentiation was associated with a marked increase in the Bmax value for a selective opioid receptor ligand and complex subcellular redistribution of selected PKC isozymes. PKC-alpha, -beta1, -beta2, -delta, and -epsilon all increased in the nucleus of ES-derived cardiac myocytes, compared with nuclei from undifferentiated cells. In both groups of cells, PKC-delta and -epsilon were mainly expressed at the nuclear level. The nuclear increase of PKC-alpha, -beta1, and -beta2 was due to a translocation from the cytosolic compartment. In contrast, the increase of both PKC-delta and PKC-epsilon in the nucleus of ES-derived cardiomyocytes occurred independently of enzyme translocation, suggesting changes in isozyme turnover and/or gene expression during cardiogenesis. No change in PKC-zeta expression was observed during cardiac differentiation. Opioid receptor antagonists prevented the nuclear increase of PKC-alpha, PKC-beta1, and PKC-beta2 and reduced cardiomyocyte yield but failed to affect the nuclear increase in PKC-delta and -epsilon. PKC inhibitors prevented the expression of cardiogenic genes and dynorphin B in ES cells and abolished their development into beating cardiomyocytes.
authors.affiliation: Department of Biomedical Sciences, Center for Biotechnology Development and Biodiversity Research, University of Sassari, Viale San Pietro 43/B, 07100 Sassari, Italy. cvent@libero.it
authors.forename: Carlo
authors.initials: C
authors.lastname: Ventura
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Zinellu
authors.forename: Emiliana
authors.initials: E
authors.lastname: Maninchedda
authors.forename: Marina
authors.initials: M
authors.lastname: Fadda
authors.forename: Margherita
authors.initials: M
authors.lastname: Maioli
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000201:enzymology; D004399:Dynorphins / Q000096:biosynthesis / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology*; D004625:Embryo, Nonmammalian; D004723:Endorphins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D004745:Enkephalins / Q000096:biosynthesis / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000196:embryology*; D007527:Isoenzymes / Q000032:analysis; D032383:Myocytes, Cardiac / Q000201:enzymology* / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000032:analysis; D009292:Narcotic Antagonists; D011493:Protein Kinase C / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D017473:Receptors, Opioid, kappa / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000502:physiology*
chemical_list: D004723:Endorphins; D004745:Enkephalins; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D009292:Narcotic Antagonists; D011498:Protein Precursors; D012333:RNA, Messenger; D017473:Receptors, Opioid, kappa; D004399:Dynorphins; C036200:rimorphin; C033660:preproenkephalin; D011493:Protein Kinase C; D018995:Myosin Heavy Chains