Xie Nina, Gong He, Suhl Joshua A, Chopra Pankaj, Wang Tao, Warren Stephen T
Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America.
Departments of Biochemistry and Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America.
PLoS One. 2016 Oct 21;11(10):e0165499. doi: 10.1371/journal.pone.0165499. eCollection 2016.
Fragile X syndrome (FXS) is a common cause of intellectual disability that is most often due to a CGG-repeat expansion mutation in the FMR1 gene that triggers epigenetic gene silencing. Epigenetic modifying drugs can only transiently and modestly induce FMR1 reactivation in the presence of the elongated CGG repeat. As a proof-of-principle, we excised the expanded CGG-repeat in both somatic cell hybrids containing the human fragile X chromosome and human FXS iPS cells using the CRISPR/Cas9 genome editing. We observed transcriptional reactivation in approximately 67% of the CRISPR cut hybrid colonies and in 20% of isolated human FXS iPSC colonies. The reactivated cells produced FMRP and exhibited a decline in DNA methylation at the FMR1 locus. These data demonstrate the excision of the expanded CGG-repeat from the fragile X chromosome can result in FMR1 reactivation.
脆性X综合征（FXS）是智力残疾的常见病因，通常是由于FMR1基因中的CGG重复扩增突变引发表观遗传基因沉默所致。在存在延长的CGG重复序列的情况下，表观遗传修饰药物只能短暂且适度地诱导FMR1重新激活。作为原理验证，我们使用CRISPR/Cas9基因组编辑技术，在含有人类脆性X染色体的体细胞杂种以及人类FXS诱导多能干细胞中切除了扩增的CGG重复序列。我们在大约67%的CRISPR切割杂种菌落以及20%的分离出的人类FXS诱导多能干细胞菌落中观察到转录重新激活。重新激活的细胞产生了脆性X智力低下蛋白（FMRP），并且在FMR1基因座处的DNA甲基化水平有所下降。这些数据表明，从脆性X染色体上切除扩增的CGG重复序列可导致FMR1重新激活。
