National Key Laboratory for Agrobiotechnology, College of biological sciences, China Agricultural University, Yuanmingyuan Xi lu, Haidian District, Beijing 100193, People's Republic of China.
Cell Biol Int. 2010 Apr 14;34(6):579-86. doi: 10.1042/CBI20100006.
Immortal bovine mammary epithelial cell lines are useful for providing an efficient indicator for transgene expression and for the technological improvement of genetic modification. The preparation of hTERT (human telomerase reverse transcriptase)-mediated immortalized MECs (mammary epithelial cells) requires a down-regulation of p16(INK4a). Here, we report the establishment of two immortal bovine MEC lines by expression of hTERT gene alone under serum-containing culture conditions. This two cell lines maintain the general characteristics of MECs and have been stably passed more than 200 generations accompanying telomere extension, and were identified as non-malignant transformation. Investigation on transcriptional profile showed a similar down-regulation in both p16(INK4a) and p53. By comparing with non-immortal hTERT-positive MECs, we speculated that there are some spontaneous p16(INK4a)-reduced cells under normal culture conditions and the immortalization required for a co-ordinate repression of p53 and p16(INK4a) signalling pathways. Interestingly, two immortal cell lines showed a significant distinction in proliferation rate, implying that other mechanisms might be involved in proliferation control.
永生牛乳腺上皮细胞系可用于提供高效的转基因表达指标，并改进遗传修饰技术。hTERT（人端粒酶逆转录酶）介导的永生化 MEC（乳腺上皮细胞）的制备需要下调 p16INK4a。在这里，我们报告了在含血清培养条件下单独表达 hTERT 基因建立的两个永生牛 MEC 系。这两个细胞系保持了 MEC 的一般特征，并伴随着端粒的延长，已稳定传代超过 200 代，且被鉴定为非恶性转化。对转录谱的研究表明，p16INK4a 和 p53 均呈相似的下调。通过与非永生 hTERT 阳性 MECs 比较，我们推测在正常培养条件下存在一些自发的 p16INK4a 减少细胞，而永生需要协调抑制 p53 和 p16INK4a 信号通路。有趣的是，两个永生细胞系在增殖率上表现出显著差异，这表明其他机制可能参与了增殖控制。
