OR04-06 Estrogen Receptor Beta (ERβ) and Gelsolin induced changes in the neuronal transcriptome & proteome

Abstract Disclosure: Y. Yildiz: None. S. Flury: None. T.R. Pak: None. Estrogen receptor beta (ERβ) is one of the main mediators of the biological effects of estrogens. ERβ translocates to the nucleus upon ligand binding to activate or repress gene transcription. ERβ binds directly to specific DNA motifs (e.g. estrogen response elements - EREs) on gene promoters, or tethers to DNA as part of a multi-protein complex with other transcription factors. Compared to ERα, ERβ is a weak transcriptional activator at EREs and genomic studies have revealed that it is preferentially tethered to AP-1 (activator protein-1) sites as part of a greater network of transcriptional regulators. Our previous study showed that ERβ protein:protein interactions are altered in the brain dependent on age and 17β-estradiol (E2) treatment in a rat model of menopause. Specifically, E2 treatment increased ERβ association with the actin-binding protein gelsolin (GSN), but this association was lost in aged animals. Further investigation revealed that GSN is essential in ERβ translocation into the nucleus, and both independently regulate promoter activity of the amyloid precursor protein (APP) and inositol-trisphosphate 3-kinase B (ITPKB) genes, both of which are heavily implicated in Alzheimer’s Disease. Our current study aimed to 1) investigate whether the regulation of human APP and ITPKB promoters was dependent on direct ERβ:DNA interactions and 2) discover the greater genomic regulatory capabilities of ERβ and GSN in neuronal cells. First, we used a naturally occurring ERβ splice variant, ERβ1Δ3, which is unable to directly bind DNA, to determine if ERβ-mediated repression of APP and ITPKB was a result of direct ERβ:DNA interactions. Our results show continued ERβ1Δ3 repression of both promoters, indicating that a majority of ERβ repression was the result of indirect ERβ:promoter interactions. We next performed RNA-Seq and mass spectrometry on neuronal cells transfected with ERβ ± siRNA-meditated GSN knockdown. Together, these results revealed a wide range of transcripts and proteins that are regulated by ERβ/GSN and could be impacted due to age-related changes in ERβ:GSN interactions. Presentation: Saturday, July 12, 2025