Dosage effect of multiple genes accounts for multisystem disorder of myotonic dystrophy type 1
Qi Yin, Hongye Wang, Na Li, Yifu Ding, Zhenfei Xie, Lifang Jin, Yan Li, Qiong Wang, Xinyi Liu, Liuqing Xu, Qing Li, Yongjian Ma, Yanbo Cheng, Kai Wang, Cuiqing Zhong, Qian Yu, Wei Tang, Wanjin Chen, Wenjun Yang, Fan Zhang, Chen Ding, Lan Bao, Bin Zhou, Ping Hu & Jinsong Li
Multisystem manifestations in myotonic dystrophy type 1 (DM1) may be due to dosage reduction in multiple genes induced by aberrant expansion of CTG repeats in DMPK, including DMPK, its neighboring genes (SIX5 or DMWD) and downstream MBNL1. However, direct evidence is lacking. Here, we develop a new strategy to generate mice carrying multigene heterozygous mutations to mimic dosage reduction in one step by injection of haploid embryonic stem cells with mutant Dmpk, Six5 and Mbnl1 into oocytes. The triple heterozygous mutant mice exhibit adult-onset DM1 phenotypes. With the additional mutation in Dmwd, the quadruple heterozygous mutant mice recapitulate many major manifestations in congenital DM1. Moreover, muscle stem cells in both models display reduced stemness, providing a unique model for screening small molecules for treatment of DM1. Our results suggest that the complex symptoms of DM1 result from the reduced dosage of multiple genes.