The formation and stabilization of a novel G-quadruplex in the 5'-flanking region of the relaxin gene.

Sen Lin, Huiping Gu, Ming Xu, Xiaojie Cui, Youyi Zhang, Wei Gao, Gu Yuan

PloS one 2012

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It has been reported that binding of STAT3 protein to the 5'-flanking region of the relaxin gene may result in downregulation of the relaxin expression. There is a Guanine(G)-rich segment located in about 3.8 Kb upstream of the relaxin gene and very close to the STAT3's binding site. In our study, NMR spectroscopy revealed the formation of G-quadruplex by this G-rich strand, and the result was confirmed by ESI mass spectrometry and CD spectroscopy. The theoretical structure of RLX G-quadruplex was constructed and refined by molecular modeling. When this relaxin G-quadruplex was stabilized by berberine(ΔTm = 10°C), a natural alkaloid from a Chinese herb, the gene expression could be up-regulated in a dose-dependent manner which was proved by luciferase assay. This result is different from the general G-quadruplex function that inhibiting the telomere replication or down-regulating many oncogenes expression. Therefore, our study reported a novel G-quadruplex in the relaxin gene and complemented the regulation mechanism about gene expression by G-quadruplexes.

Citation

Sen Lin, Huiping Gu, Ming Xu, Xiaojie Cui, Youyi Zhang, Wei Gao, Gu Yuan. The formation and stabilization of a novel G-quadruplex in the 5'-flanking region of the relaxin gene. PloS one. 2012;7(2):e31201