Stabilization of VEGF i-motif structure by CpG methylation
Stabilization of VEGF i-motif structure by CpG methylation
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DOI：
10.1016/j.bbrc.2022.01.054
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发表时间：
2022-01-22
影响因子：
3.1
通讯作者：
Yoshida, Wataru
中科院分区：
文献类型：
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作者：
Kimura, Kosuke;Oshikawa, Daiki;Yoshida, Wataru
插入基序（intercalated motif，i-motif）是在酸性条件下由插入的半质子化胞嘧啶碱基对（C-C+）形成的非规范核酸结构。i-motif结构的形成涉及生物过程，如转录调控。因此，鉴定控制i-基序形成的因子对于阐明其控制的细胞功能是重要的。我们先前报道了VEGF G-四链体结构通过CpG甲基化而稳定。在这项研究中，CpG甲基化对VEGF i基序结构稳定性的影响进行了研究。VEGF i基序形成寡核苷酸在CpG位点上含有四个胞嘧啶，并且四个胞嘧啶中的三个（C4、C15和C20）参与i基序结构中的C-C+形成。圆二色性（CD）光谱分析表明，在pH 5.0的25 mM二甲胂酸钠缓冲液中，完全CpG甲基化使i基序结构的中间转变（pHT）的pH增加0.1，并且使解链温度（Tm）增加5.1 ℃。此外，C4、C15和C20处的单一甲基化使缓冲液中的Tm分别增加0.5、1.7和2.0 ° C。这些结果表明，CpG甲基化稳定了VEGF i基序结构。(c)2022爱思唯尔公司All rights reserved.
The intercalated motif (i-motif) is a non-canonical nucleic acid structure formed by intercalated hemiprotonated cytosine base pairs (C-C+) under acidic conditions. The i-motif structure formation is involved in biological processes such as transcription regulation. Therefore, the identification of factors controlling i-motif formation is important in elucidating the cellular functions it controls. We previously reported that the VEGF G-quadruplex structure is stabilized by CpG methylation. In this study, the effect of CpG methylation on the stability of the VEGF i-motif structure was investigated. The VEGF i-motifforming oligonucleotide contains four cytosines on CpG sites, and three of the four cytosines (C4, C15, and C20) are involved in C-C+ formation in the i-motif structure. Circular dichroism (CD) spectra analysis demonstrated that full CpG methylation increased the pH of mid transition (pHT) of the i-motif structure by 0.1, and the melting temperature (Tm) by 5.1 degrees C in 25 mM sodium cacodylate buffer at pH 5.0. Moreover, single methylation at C4, C15, and C20 increased Tm by 0.5, 1.7, and 2.0 degrees C in the buffer, respectively. These results demonstrated that CpG methylation stabilized the VEGF i-motif structure. (c) 2022 Elsevier Inc. All rights reserved.