Price James D, Park Ki-Youb, Chen Jiadong, Salinas Ryan D, Cho Mathew J, Kriegstein Arnold R, Lim Daniel A
Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Developmental and Stem Cell Biology Graduate Program, Department of Neurological Surgery.
Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Neurological Surgery.
J Neurosci. 2014 Sep 10;34(37):12560-7. doi: 10.1523/JNEUROSCI.3159-13.2014.
Non-neurogenic cell types, such as cortical astroglia and fibroblasts, can be directly converted into neurons by the overexpression of defined transcription factors. Normally, the cellular phenotype of such differentiated cells is remarkably stable and resists direct cell transdifferentiation. Here we show that the Ink4a/Arf (also known as Cdkn2a) locus is a developmental barrier to direct neuronal transdifferentiation induced by transcription factor overexpression. With serial passage in vitro, wild-type postnatal cortical astroglia become progressively resistant to Dlx2-induced neuronal transdifferentiation. In contrast, the neurogenic competence of Ink4a/Arf-deficient astroglia is both greatly increased and does not diminish through serial cell culture passage. Electrophysiological analysis further demonstrates the neuronal identity of cells induced from Ink4a/Arf-null astroglia, and short hairpin RNA-mediated acute knockdown of p16Ink4a and p19Arf p16(Ink4a) and p19(Arf) indicates that these gene products function postnatally as a barrier to cellular transdifferentiation. Finally, we found that mouse fibroblasts deficient for Ink4a/Arf also exhibit greatly enhanced transcription factor-induced neuronal induction. These data indicate that Ink4a/Arf is a potent barrier to direct neuronal transdifferentiation and further suggest that this locus functions normally in the progressive developmental restriction of postnatal astrocytes.
非神经源性细胞类型，如皮质星形胶质细胞和成纤维细胞，可通过过表达特定转录因子直接转化为神经元。通常情况下，这类分化细胞的细胞表型非常稳定，能够抵抗直接的细胞转分化。在此我们表明，Ink4a/Arf（也称为Cdkn2a）基因座是转录因子过表达诱导的直接神经元转分化的发育障碍。随着体外连续传代，野生型出生后皮质星形胶质细胞对Dlx2诱导的神经元转分化的抗性逐渐增强。相比之下，Ink4a/Arf缺陷型星形胶质细胞的神经源性能力显著增强，并且在连续细胞培养传代过程中不会减弱。电生理分析进一步证明了从Ink4a/Arf缺失的星形胶质细胞诱导而来的细胞具有神经元特性，并且短发夹RNA介导的p16Ink4a和p19Arf的急性敲低表明，这些基因产物在出生后作为细胞转分化的障碍发挥作用。最后，我们发现Ink4a/Arf缺陷的小鼠成纤维细胞也表现出转录因子诱导的神经元诱导能力大大增强。这些数据表明，Ink4a/Arf是直接神经元转分化的强大障碍，并进一步表明该基因座在出生后星形胶质细胞的渐进性发育限制中正常发挥作用。
