G-quadruplex–forming GGA repeat region functions as a negative regulator of the Ccnb1ip1 enhancer. Issue 9 (2nd September 2019)

• Record Type: Journal Article
• Authors: Islam, Izzul; Baba, Yuji; Witarto, Arief Budi; Yoshida, Wataru
• Is Part Of: Bioscience, biotechnology, and biochemistry. Volume 83:Issue 9(2019)
• Page Start: 1697
• Page End: 1702
• Publication Date: 2019-09-02
• Subjects: G-quadruplex -- GGA repeat -- enhancer -- Ccnb1ip1; Biotechnology -- Periodicals; Biochemistry -- Periodicals; 660.6
• DOI: 10.1080/09168451.2019.1611412
• Languages: English
• ISSNs: 0916-8451

Abstract

ABSTRACT: An enhancer located upstream of the transcriptional start site of Ccnb1ip1 containing two GGA-rich regions and a 14-GGA repeat (GGA)14 region has been previously identified. Three copies of four GGA repeats in the c-myb promoter that form a tetrad:heptad:heptad:tetrad (T:H:H:T) dimerized G-quadruplex (G4) structure reportedly functions as both a transcriptional repressor and activator. Here, the secondary structures of the two GGA-rich and (GGA)14 regions were analyzed using circular dichroism spectral analysis, which indicated that the two GGA-rich DNAs formed parallel-type G4 structures, whereas (GGA)14 DNA formed the T:H:H:T dimerized G4 structure. Reporter assays demonstrated that individual regions did not show enhancer activity; however, the deletion of the (GGA)14 region resulted in 1.5-fold higher enhancer activity than that of the whole enhancer. These results indicate that the (GGA)14 region that forms the T:H:H:T dimerized G4 structure functions as a negative regulator of the Ccnb1ip1 enhancer. ABSTRACT: : The (GGA)14 region that forms a dimerized G-quadruplex structure functions as a negative regulator of the Ccnb1ip1 enhancer.