Molecular mechanisms underlying nuclear reprogramming of somatic cells

诱导多能干细胞可以通过在体细胞中引入四种重编程因子而产生。我们发现用c-Myc产生的嵌合体小鼠具有高致瘤性。为了克服这个问题，我们可以在改良的条件下产生不含Myc的iPS细胞。但与c-Myc生成的iPS细胞相比，Myc缺失的iPS细胞表现出更少的多能性。接下来，我们探讨了可以替代c-Myc功能的因素。我们找到了L-Myc作为候选。我们可以证实，L-Myc提高了iPS的生成效率，而L-Myc的致瘤性几乎没有观察到。因此，我们可以使用L-Myc获得更安全的iPS细胞。我们利用诱导多能干细胞衍生的神经细胞建立了检测诱导多能干细胞安全性的系统。我们还建立了iPS细胞向肝细胞、血细胞和心肌细胞的体外分化方法。下一代测序仪（NGS）是分析iPS细胞遗传特性的有力工具。我们利用NGS分析了iPS细胞的基因表达、DNA甲基化和剪接模式的变化

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