Repression of Translation of Human Estrogen Receptor α by G-Quadruplex Formation

Abstract

Tissue-specific expression of the human estrogen receptor alpha gene (ESR1) is achieved through multiple promoter sequences resulting in various mRNA transcripts encoding a common protein but differing in their 5'-untranslated region (5'-UTR). Many cancers are estrogen-sensitive with neoplastic growth stimulated through the estrogen receptor, a transcription factor that regulates developmental genes. We demonstrate that the human ESR1 gene is rich in potential quadruplex-forming sequences with 3 of 20 identified within exonic regions. In particular, we show using CD, UV, and NMR spectroscopy that a stable DNA G-quadruplex motif is formed within the exon C gene sequence. This motif, which PCR shows is transcribed in normal and neoplastic endometrium and in MCF-7 cells, forms a stable RNA quadruplex demonstrable by CD and UV analysis. Cloning the exon C G-quadruplex sequence upstream of a luciferase reporter gene caused a 6-fold reduction of enzymatic activity compared to a mutant sequence. We conclude that the exon C G-quadruplex motif is present in the 5'-UTR of the mRNA transcript, where it modulates the efficiency of translation.

Translational Repression of the Disintegrin and Metalloprotease ADAM10 by a Stable G-quadruplex Secondary Structure in Its 5′-Untranslated Region

“…Mutation of the ADAM10 G-quadruplex signature motif resulted in a 3-fold increase of luciferase activity for both mutants compared with the wild-type 5Ј-UTR. These findings are again in agreement with recently described results for the 5Ј-UTR mRNAs of N-ras (35), ESR-1 (38), Bcl-2 (42), and TRF2 (41).…”

“…On the other hand, G-quadruplex signature motifs occur predominantly at the 5Ј end of the 5Ј-UTR, which suggests that G-quadruplex secondary structures are involved in translational regulation either by inhibiting the formation of the initiation complex or by inhibition of the scanning ribosome (30). In agreement with this hypothesis, a series of recent reports demonstrate that the 5Ј-UTRs of N-ras, Zic-1, membrane-type matrix metalloproteinase 3, ESR-1, Bcl-2, and others contain a G-quadruplex motif that inhibits the translation of their downstream genes (35)(36)(37)(38)(39)(40)(41)(42).…”

“…The ADAM10 G-quadruplex Motif Inhibits Translation of a Luciferase Reporter in Vivo-Recently, it was shown that G-quadruplex motifs within 5Ј-UTRs inhibit translation of their downstream gene in vitro and in vivo (35)(36)(37)(38)(39)(40)(41)(42). Moreover, artificially introduced RNA-G-quadruplex motifs near the ribosomal binding site suppress bacterial gene expression (58).…”

“…The basic structural core motif of G-quadruplexes consists of a series of G-quartet planes, each of which consists of four guanines connected by Hoogsteen-hydrogen bonds and stabilized by monovalent ions, particularly potassium ions (31-34). There is growing evidence that the formation of G-quadruplex secondary structures within 5Ј-UTRs results in translational repression of a number of different mRNAs, including N-ras, Zic-1, membrane-type matrix metalloproteinase 3, ESR-1, and Bcl-2 (35)(36)(37)(38)(39)(40)(41)(42). Similar to the IRE stem loop, the stability of G-quadruplex structures could be modulated by RNA binding proteins such as FMRP or members of the hnRNP A family (43,44).…”

An RNA G-quadruplex in the 3' UTR of the proto-oncogene PIM1 represses translation

“…[1][2][3][4][5][6][7][8][9][10][11] In addition, RNA G-quadruplex structures can also stimulate mitochondrial transcription termination 12 and regulate alternative splicing in TP53 intron 3. 13 In addition, a G-quadruplex close to a cleavage sites in the 3' UTR of insulinlike growth factor II mRNA has been proposed and its structure formation has been demonstrated in vitro.…”