Methylation of specific CpG sites in the <i>Oxtr</i> minimal promoter inhibits transcription.

<p><b>A</b>) A schematic depiction of the distinct <i>Oxtr</i> promoter/<i>EYFP</i> constructs used; An <i>EYFP</i> gene was coupled to a minimal promoter (positions −1417 to +46) of the mouse <i>Oxtr</i> gene (<i>Unmodified</i>). This construct was modified by a C to A mutation at CpG sites 1 (<i>Mut 1</i>) or site 7 (<i>Mut 7</i>) or by deleting the ∼400 bp amplicon region (<i>Del</i>). <b>B,C</b>) EYFP mean fluorescence intensity measured in GT1-7 cells that were transfected with either (<b>B</b>) untraeatd or (<b>C</b>) methyltransferase-treated <i>Oxtr</i> promoter/<i>EYFP</i> constructs. No significant differences were found among the untreated plasmids whereas a highly significant difference was found among the methyltransferase-treated plasmids. <b>D</b>) A comparison between the treatedand untreated versions of all plasmids. Highly significant differences were found only in the cases of the <i>Unmodified</i> and <i>Mut 1</i> plasmids. <b>Statistics</b>: <b>B</b>) one-way ANOVA F₍₃₎ = 2.32, <i>p</i>>0.1. <b>C</b>) - one-way ANOVA F₍₃₎ = 9.4, <i>p</i><0.01, * differ from <i>Unmodified</i>, <i>p</i><0.05, n = 5. <b>D</b>) t-test, *<i>p</i><0.05/4.