title: Membrane-initiated estradiol signaling increases tyrosine hydroxylase promoter activity with ER alpha in PC12 cells.
abstract: Tyrosine hydroxylase (TH) promoter activity is induced by 17beta-estradiol (E(2)) in PC12 cells expressing estradiol receptor-alpha (ERalpha) requiring a cAMP/calcium response element (CRE/CaRE) at -45. To examine whether membrane-initiated estradiol signaling is underlying this induction, cells co-transfected with TH reporter construct and ERalpha expression vector were exposed to membrane-impermeant estradiol conjugate (beta-estradiol-6-(O-carboxy-methyl) oxime-bovine serum albumin, E(2)BSA). TH promoter activity was elevated by E(2)BSA in dose- and time-dependent manner. E(2)BSA also elicited rapid phosphorylation of CRE binding protein (CREB) and increased CRE-driven promoter activity. Over-expression of dominant negative forms of CREB, with mutations in DNA binding or phosphorylation site, prevented TH promoter response to E(2)BSA. Pre-treatment with protein kinase A (PKA) and MEK inhibitors reduced E(2) dependent phosphorylation of CREB and ERK, and also decreased induction of TH promoter activity by E(2) or E(2)BSA. Blocking S-palmitoylation of ERalpha with C451A mutation and/or pre-treatment with 2-Bromopalmitate did not prevent but instead enhanced E(2) or E(2)BSA-elicited induction of TH promoter activity. These findings reveal, for the first time, that estradiol induction of TH gene transcription with ERalpha in PC12 cells involves membrane-initiated estradiol signaling, rapid activation of dual PKA/MEK signaling pathways, leading to CREB phosphorylation, acting at CRE/CaRE. The data demonstrate possible mechanism whereby estradiol affects catecholaminergic systems in vivo.
authors.affiliation: Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, New York, USA.
authors.forename: Shreekrishna
authors.initials: S
authors.lastname: Maharjan
authors.forename: Lidia I
authors.initials: LI
authors.lastname: Serova
authors.forename: Esther L
authors.initials: EL
authors.lastname: Sabban
mesh_terms: D000818:Animals; D050882:CREB-Binding Protein / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D015536:Down-Regulation / Q000235:genetics; D004790:Enzyme Induction / Q000235:genetics; D004958:Estradiol / Q000502:physiology*; D047628:Estrogen Receptor alpha / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D009154:Mutation; D016716:PC12 Cells; D010766:Phosphorylation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000502:physiology*; D051381:Rats; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D015533:Transcriptional Activation / Q000235:genetics / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D015854:Up-Regulation / Q000235:genetics
chemical_list: D047628:Estrogen Receptor alpha; D008565:Membrane Proteins; D004958:Estradiol; D014446:Tyrosine 3-Monooxygenase; D050882:CREB-Binding Protein