The 309th Hospital of Chinese People's Liberation Army, Beijing, China.
Arch Med Res. 2012 Jan;43(1):15-20. doi: 10.1016/j.arcmed.2012.02.001. Epub 2012 Feb 26.
Hypoxia-associated changes of telomeric structure in cell cultures have been analyzed mainly in cancer cells, stem cells, or cells transduced with vectors containing the telomerase gene, but not in somatic cells. The stability of telomere structure has been reported to be associated with subtelomeric methylation status. However, there are no reports of epigenetic alterations of telomeric regions of human somatic cells under hypoxia. This study aims at detecting and analyzing the subtelomeric methylation status in human somatic cells cultured under hypoxia.
Mean telomere length and telomerase activity of human umbilical vein endothelial cells (HUVECs) cultured in hypoxic conditions were measured. Subtelomeric methylation status of these cells was assessed by genomic Southern blot with telomere DNA probe using methylation-sensitive and -insensitive isoschizomers, MspI and HpaII.
The telomerase activity in HUVECs correlated inversely with the oxygen concentration. Mild hypoxia (10 or 15% oxygen) increased the telomere lengths, whereas the telomere lengths did not appear to change when <1% O(2). The subtelomere of the shortest telomere range was methylated the most at 1% O(2).
Subtelomeric hypermethylation of short telomeres at 1% O(2) compared to milder hypoxia implied that the subtelomeric hypermethylation may yield telomere stability and favor the cell survival of short telomere-bearing cells.
在细胞培养物中，与缺氧相关的端粒结构变化主要在癌细胞、干细胞或转染含有端粒酶基因载体的细胞中进行了分析，但在体细胞中尚未进行分析。已有报道称，端粒结构的稳定性与亚端粒甲基化状态有关。然而，目前尚无关于人类体细胞在缺氧下端粒区域的表观遗传改变的报道。本研究旨在检测和分析缺氧培养的人脐静脉内皮细胞（HUVEC）中端粒的亚端粒甲基化状态。
测量在缺氧条件下培养的人脐静脉内皮细胞（HUVEC）中端粒酶的平均端粒长度和活性。使用端粒 DNA 探针通过基因组 Southern 印迹，用甲基化敏感和不敏感的同裂酶 MspI 和 HpaII 评估这些细胞的亚端粒甲基化状态。
HUVEC 中端粒酶的活性与氧浓度呈负相关。轻度缺氧（10%或 15%氧气）会增加端粒长度，而当氧浓度<1%时，端粒长度似乎没有变化。最短端粒范围内的亚端粒在 1% O2 时甲基化程度最高。
与轻度缺氧相比，1% O2 时短端粒的亚端粒过度甲基化表明，亚端粒过度甲基化可能产生端粒稳定性，并有利于短端粒携带细胞的存活。
