17β-Estradiol Stimulates Mouse Neuropeptide Y-Y₁ Receptor Gene Transcription by Binding to Estrogen Receptor Alpha in Neuroblastoma Cells

Abstract

Several studies have shown that neuropeptide Y (NPY) is involved in the stimulation of gonadotropin hormone releasing hormone (GnRH) and luteinizing hormone (LH) secretion and that these effects are modulated by gonadal steroid feedback. The NPY regulation of GnRH release is probably mediated by the activation of the Y₁ receptor subtype. In this study we examined the regulation of the Y₁ receptor gene transcription by estrogens in transiently transfected NG108-15 neuroblastoma glioma cells. A chimeric plasmid containing the murine Y₁ receptor promoter fused to the firefly luciferase reporter gene was induced by approximately 2-fold in response to 17β-estradiol treatment. The estrogen-mediated enhancement of luciferase activity was dose-dependent, blocked by the estrogen receptor (ER) antagonist ICI 182,780, and was strictly dependent on the presence of ERα, since it occurred only in NG108-15 cells cotransfected with an expression vector for the human ER. Mutational analysis was performed to investigate whether the hemipalindromic estrogen-responsive elements (EREs) flanking the Y₁ receptor gene are responsible for conferring estradiol inducibility to the Y₁ receptor gene promoter. Mutation of the ERE1 half site at position –932, or mutation of the ERE2 half site at position –809, relative to the ATG, failed to affect the 17β-estradiol-mediated enhancement of luciferase activity. Conversely, mutation of both ERE1 and ERE2 half sites completely abolished activation of luciferase activity induced by estrogen. We also examined whether 17β-estradiol stimulates the transcriptional activity of the Y₁ receptor gene by binding to ERβ. Results demonstrated that luciferase activity was not modulated by estrogens when cells were transfected with the expression plasmid bearing the human ERβ. Moreover coexpression of both ERα and ERβ completely abolished the estrogen-induced activation of luciferase activity observed in the presence of ERα. Our data suggest that estrogens activate Y₁ receptor gene transcription possibly via a direct interaction of ERα with the hemipalindromic EREs flanking the Y₁ receptor gene.

Estrogen Up-regulates Neuropeptide Y Y1 Receptor Expression in a Human Breast Cancer Cell Line

“…3B). Studies in NG-108-15 cells transfected with ERa and/or ERh showed that the presence of ERh attenuates basal as well as ERa-induced Y1R gene promoter activity (32). These findings are consistent with earlier reports that activation of ERh can inhibit ERa-mediated activity in certain cell lines (33).…”

“…Human genomic cloning studies revealed that three different promoters regulate the Y1R gene in a tissue-specific manner (35). A chimeric plasmid containing mouse Y1R promoter linked to luciferase reporter gene activity was increased 2-fold by estrogen (32) in transfected NG-108-15 cells. In the same study, introducing mutations in both ERE sites abolished the estrogen-induced gene activity (32).…”

“…A chimeric plasmid containing mouse Y1R promoter linked to luciferase reporter gene activity was increased 2-fold by estrogen (32) in transfected NG-108-15 cells. In the same study, introducing mutations in both ERE sites abolished the estrogen-induced gene activity (32). These findings support the hypothesis that estrogeninduced up-regulation of Y1R in MCF-7 cells likely involves the activation of ERa and its binding to ERE sites present in the promoter region.…”

Estrogen and Thyroid Hormone Receptor Interactions: Physiological Flexibility by Molecular Specificity

“…When the predominant ER isoform present in brain areas is the noninducing ER␤ isoform, this is precisely the case. The inability of ER␤ to induce transcription in response to 17␤-estradiol has also been reported in transiently transfected NG108 -15 neuroblastoma glioma cells using a neuropeptide Y-Y1 receptor gene promoter (117). This receptor promoter has two half-site ERE, and estrogen-mediated transcription is strictly dependent on the presence of transfected ER␣.…”

Suppressive Action of Orexin A on Pulsatile Luteinizing Hormone Secretion Is Potentiated by a Low Dose of Estrogen in Ovariectomized Rats

“…NPY has been suggested to be involved in the feeding stimulation action of orexins through mediation of Y1 and Y5 receptors [3, 10, 39]. Further, similar to orexin A, icv injection of NPY was either stimulatory [40, 41]or inhibitory [40, 42]to LH secretion depending on the endocrine status of the animals, mediated by either Y1, Y4 and/or Y5 receptors [43, 44, 45, 46], and the NPY/Y1 receptor system has been shown to be activated by estrogen [47]. It is possible then that estrogen potentiates the action of orexin A by activating the NPY/Y1 system.…”