Danish-Chinese Centre for Proteases and Cancer, Department of Molecular Biology, University of Aarhus, 8000 Aarhus C, Denmark.
Chin J Cancer Res. 2011 Jun;23(2):92-8. doi: 10.1007/s11670-011-0092-5.
To investigated whether epigenetic mechanisms contribute to the variable expression of variable protease nexin1(PN-1) encoded by the SERPINE2 gene in different cell types.
Working with 5 human cell lines, we determined the CpG methylation status within two CpG islands in the SERPINE2 gene by bisulphate sequencing and the PN-1 mRNA level by Q-RT PCR.
A CpG island spanning the transcription initiation site showed little methylation in 3 of the cell lines and substantial methylation in 2 of the cell lines. A CpG island covering the translation starting site showed full methylation in all investigated cell lines. Methylation within the CpG island was not randomly distributed, but showed accumulation at specific sites. However, we were not able to distinguish any patterns which related the methylation frequency to the gene expression level. Inhibition of CpG methylation with 5-aza-2'-deoxycytidine led to a several fold increase in PN-1 mRNA levels, but based on the results on CpG methylation in the CpG island spanning the transcript, the effect is most likely indirect.
We have carefully mapped the CpG methylation pattern in two CpG islands in the 5' part of the SERPINE2 gene without finding any obvious inverse correlation between methylation frequency and expression level.
研究表观遗传机制是否导致丝氨酸蛋白酶抑制剂 2 基因（SERPINE2）编码的可变蛋白酶神经素 1（PN-1）在不同细胞类型中的表达具有可变性。
通过亚硫酸氢盐测序，我们在 5 个人类细胞系中确定了 SERPINE2 基因内两个 CpG 岛的 CpG 甲基化状态，并通过 Q-RT-PCR 确定了 PN-1 mRNA 水平。
跨越转录起始位点的 CpG 岛在 3 个细胞系中显示出很少的甲基化，而在 2 个细胞系中显示出大量的甲基化。覆盖翻译起始位点的 CpG 岛在所有研究的细胞系中均完全甲基化。CpG 岛内的甲基化不是随机分布的，而是在特定位置聚集。然而，我们无法区分任何与基因表达水平相关的甲基化频率模式。用 5-氮杂-2'-脱氧胞苷抑制 CpG 甲基化可使 PN-1 mRNA 水平增加数倍，但基于跨越转录的 CpG 岛的 CpG 甲基化结果，这种影响很可能是间接的。
我们仔细绘制了 SERPINE2 基因 5'端两个 CpG 岛的 CpG 甲基化模式，没有发现甲基化频率和表达水平之间存在明显的反比关系。
