外源基因转染导致小鼠体细胞过快衰老及p16^(INK4a)表达水平变化

Accelerated Somatic Cell Senescence and Changes in p16^(INK4a) Expression after Exogenous DNA Transfection

对小鼠胎儿成纤维细胞进行外源基因转染时发现,外源基因转染后的小鼠体细胞染色体端粒的长度以每代47 bp碱基缩短;在转染后的衰老细胞中,或细胞随着增龄,p16INK4 5’-调控区DNA甲基化程度逐渐降低;利用RT-PCR与Northern blot证明,衰老细胞与年轻细胞中的p16INK4a基因的表达水平存在显著差异,传代45代的细胞和外源基因转染后的衰老细胞p16INK4a基因的表达水平大约是原代细胞的12～16倍,而原代细胞与20代细胞间的差异很小。外源基因转染后的衰老细胞核移植后能支持克隆胚胎的体外早期发育。

During the transfection of mouse embryonic fibroblasts （MEF）, we found these cells became senescent, appearing enlarged with hollow cytoplasm and multinucleated. The telomere lengths of these senescent MEFs were significantly shorter than primary untransfected MEFs. In senescent MEF cells, DNA methylation of p16^INK4α 5＇-regulatory region showed gradual reduction as cells aged. RT-PCR and Northern blot demonstrated that the expression of p16^INK4α in transfected senescent cells was 12-16 times more than primary cells. The senescent transfected MEF cells as donors of nuclei could support the early development of cloned embryos after nuclear transfer.