Molecular mechanisms underlying nuclear reprogramming of somatic cells

iPS细胞可以通过向体细胞中引入四种重编程因子来产生。我们发现用c-Myc产生的嵌合体小鼠显示出高致瘤性。为了克服这个问题，我们可以在改进的条件下产生不含Myc的iPS细胞。但是与用c-Myc产生的iPS细胞相比，Myc减去iPS细胞显示出较少的多能性。接下来，我们探索了可以替代c-Myc功能的因素。我们发现L-Myc是候选人。我们可以确认L-Myc增强了iPS产生的效率，并且几乎没有观察到L-Myc的致瘤性。因此，我们可以利用L-Myc获得更安全的iPS细胞。我们使用iPS细胞衍生的神经元细胞建立了检查iPS细胞安全性的系统。我们还建立了iPS细胞体外分化为肝细胞、血细胞和心肌细胞的方法。新一代测序仪（NGS）是分析iPS细胞遗传特性的有力工具。我们利用NGS技术分析了iPS细胞基因表达、DNA甲基化、剪接模式的变化

iPS cells can be generated by introduction of four reprogramming factors into somatic cells. We have found that chimera mice produced with c-Myc show high tumorigenicity. To overcome this issue, we could generate iPS cells without Myc under the modified conditions. But Myc minus iPS cells showed less pluripotency compared to iPS cells generated with c-Myc. Next, we explored the factors which could replace the c-Myc function. We found L-Myc as a candidate. We could confirm that L-Myc enhances the efficiency of iPS generation and that the tumorigenicity of L-Myc is hardly observed. So, we can obtain the safer iPS cells using L-Myc. We established the system to examine the safety of iPS cells using the iPS cells-derived neuronal cells. We also established the differentiation methods of iPS cells into hepatocytes, blood cells, and cardiomyocytes in vitro. Next generation sequencer(NGS) is very powerful tool for analysis of genetic properties of iPS cells. We have analyzed the gene expression, DNA methylation, changes of splicing pattern in iPS cells using NGS