title: A small RNA derived from RNA coactivator SRA blocks steroid receptor signaling via inhibition of Pus1p-mediated pseudouridylation of SRA: evidence of a novel RNA binding domain in the N-terminus of steroid receptors.
abstract: Estrogen receptors (ERs) and androgen receptors (ARs) are important targets for cancer therapy; however, the efficacy of receptor antagonists is limited, and alternative strategies are needed. Steroid receptor RNA Activator (SRA) is a long, noncoding RNA coactivator (although some protein-encoding 5' splice variants have also been reported) that requires pseudouridylation by Pus1p to stimulate steroid receptor signaling. A uridine at position 206 (U206), which is located in small hairpin structure STR5 in the conserved SRA core sequence, is a critical target for pseudouridylation. We assessed if synthetic STR5 could serve as a novel competitive inhibitor of ERα and AR signaling by disrupting the Pus1p-SRA-steroid receptor axis. STR5 specifically inhibited Pus1p-dependent pseudouridylation of SRA with higher efficiency than STR5 mutant U206A. We show that SRA binds to the N-terminal domain (NTD) of ERα and AR with high affinity despite the absence of a recognizable RNA binding motif (RBM). Finally, we show that STR5 specifically inhibits ERα- and AR-dependent transactivation of target genes in steroid-sensitive cancer cells, consistent with disruption of the targeted Pus1p-SRA pathway. Together, our results show that the NTD of ERα and AR contains a novel RBM that directly binds SRA, and that STR5 can serve as a novel class of RNA inhibitor of ERα and AR signaling by interfering with Pus1p-mediated SRA pseudouridylation. Targeting this unexplored receptor signaling pathway may pave the way for the development of new types of cancer therapeutics.
authors.affiliation: Department of Medicine, Cancer Center, Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Sajal K
authors.initials: SK
authors.lastname: Ghosh
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Patton
authors.forename: Remco A
authors.initials: RA
authors.lastname: Spanjaard
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor; D017931:DNA Primers; D006801:Humans; D006836:Hydro-Lyases / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D011560:Pseudouridine / Q000378:metabolism*; D012313:RNA / Q000378:metabolism*; D062085:RNA, Long Noncoding / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D011987:Receptors, Steroid / Q000737:chemistry / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D017931:DNA Primers; D062085:RNA, Long Noncoding; D011987:Receptors, Steroid; C405423:steroid receptor RNA activator; D011560:Pseudouridine; D012313:RNA; D006836:Hydro-Lyases; C022479:pseudouridylate synthetase