title: Neurosteroid dehydroepiandrosterone exerts anti-apoptotic effects by membrane-mediated, integrated genomic and non-genomic pro-survival signaling pathways.
abstract: Dehydroepiandrosterone (DHEA) protects neural crest-derived PC12 cells from serum deprivation-induced apoptosis via G protein-associated specific plasma membrane-binding sites (mDBS). Here, we studied the signaling pathways involved in the pro-survival effects of DHEA-mediated activation of the mDBS binding sites. Membrane impermeable DHEA-bovine serum albumin (BSA) conjugate induced an acute phosphorylation of the prosurvival kinases Src, protein kinase A (PKA), MEK1/2/ERK1/2, and PI3K/Akt in serum deprived PC12 cells in parallel to an elevation of intracellular cAMP. The physiological significance of these findings was further assessed in a series of experiments using several selective pro-survival kinase inhibitors. Our combined findings suggest that the following sequence of events may take place following activation of mDBS binding sites: DHEA-BSA induces an acute but transient sequential phosphorylation of the pro-survival kinases Src/PKC(a/b)/MEK1/2/ERK1/2 which, in their turn, activate transcription factors cAMP responsive element binding protein and nuclear factor kappa B which induce the expression of the anti-apoptotic Bcl-2 genes. In parallel, DHEA-BSA increases intracellular cAMP, and the subsequent phosphorylation of PKA kinase and of cAMP responsive element binding protein. Finally, DHEA-BSA induces phosphorylation of PI3K/Akt kinases which, subsequently, lead to phosphorylation/deactivation of the pro-apoptotic Bad. Our findings suggest that the neurosteroid DHEA affects neural crest-derived cell survival by multiple pro-survival signaling pathways comprising an integrated system of non-genomic and genomic mechanisms.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Crete, Heraklion, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Charalampopoulos
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Margioris
authors.forename: Achille
authors.initials: A
authors.lastname: Gravanis
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D023281:Genomics; D006624:Hippocampus / Q000166:cytology; D008954:Models, Biological; D016328:NF-kappa B / Q000378:metabolism; D016716:PC12 Cells; D037342:Pertussis Toxin / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D000276:Adjuvants, Immunologic; D016895:Culture Media, Serum-Free; D004791:Enzyme Inhibitors; D016328:NF-kappa B; D003687:Dehydroepiandrosterone; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D019061:src-Family Kinases; D017868:Cyclic AMP-Dependent Protein Kinases