title: Akt-mediated survival of oligodendrocytes induced by neuregulins.
abstract: Neuregulins have been implicated in a number of events in cells in the oligodendrocyte lineage, including enhanced survival, mitosis, migration, and differentiation. At least two signaling pathways have been shown to be involved in neuregulin signaling: the phosphatidylinositol (PI)-3 kinase and the mitogen-activated protein kinase pathways. In the present studies, we examined the signaling pathway involved in the survival function of heregulin, focusing on heregulin-induced changes in Akt activity in cultured glial cells, and the consequences of Akt activation in cells in the oligodendrocyte lineage. Heregulin binds erbB receptors, and in our studies, primary cultures of both oligodendrocyte progenitor cells and differentiating oligodendrocytes expressed erbB2, erbB3, and erbB4 receptors. In C6 glioma cells and primary cultures of oligodendrocytes, heregulin induced time- and dose-dependent Akt phosphorylation at Ser(473) in a wortmannin-sensitive manner. To investigate further the signaling pathway for heregulin in glial cells, BAD was overexpressed in C6 glioma cells. In these cells, heregulin induced phosphorylation of BAD at Ser(136). Apoptosis of oligodendrocyte progenitor cells induced by growth factor deprivation was effectively blocked by heregulin in a wortmannin-sensitive manner. Overexpression of dominant negative Akt but not of wild-type Akt by adenoviral gene transfer in primary cultures of both oligodendrocytes and their progenitors induced significant apoptosis through activation of the caspase cascade. The present data suggest that the survival function of heregulin is mediated through the PI-3 kinase/Akt pathway in cells in the oligodendrocyte lineage and that the Akt pathway may be quite important for survival of cells in this lineage.
authors.affiliation: Department of Neurosciences, The Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Flores
authors.forename: B S
authors.initials: BS
authors.lastname: Mallon
authors.forename: T
authors.initials: T
authors.lastname: Matsui
authors.forename: W
authors.initials: W
authors.lastname: Ogawa
authors.forename: A
authors.initials: A
authors.lastname: Rosenzweig
authors.forename: T
authors.initials: T
authors.lastname: Okamoto
authors.forename: W B
authors.initials: WB
authors.lastname: Macklin
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics; D020169:Caspases / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D019070:Cell Lineage / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D066246:ErbB Receptors / Q000378:metabolism; D015870:Gene Expression; D005799:Genes, Dominant; D020890:Neuregulin-1 / Q000378:metabolism / Q000494:pharmacology; D020880:Neuregulins / Q000378:metabolism* / Q000494:pharmacology; D009836:Oligodendroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D020893:Receptor, ErbB-3 / Q000378:metabolism; D066247:Receptor, ErbB-4; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014162:Transfection; D000077191:Wortmannin; D051025:bcl-Associated Death Protein
chemical_list: D000730:Androstadienes; D002352:Carrier Proteins; D020169:Caspases; D066246:ErbB Receptors; D020890:Neuregulin-1; D020880:Neuregulins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D066247:Receptor, ErbB-4; D000077191:Wortmannin; D051025:bcl-Associated Death Protein; C494821:Bad protein, rat; C087230:heregulin beta1; C587691:Erbb4 protein, rat; C494920:Akt1 protein, rat