Cell Research (2017) 27:483–504. doi:10.1038/cr.2017.18; published online 31 January 2017
Visualization of aging-associated chromatin alterations with an engineered TALE system
Ruotong Ren1,2,*, Liping Deng1,2,3,*, Yanhong Xue1,2,*, Keiichiro Suzuki4,*, Weiqi Zhang1,2, Yang Yu5, Jun Wu4, Liang Sun6, Xiaojun Gong7, Huiqin Luan1, Fan Yang8, Zhenyu Ju9, Xiaoqing Ren1, Si Wang1, Hong Tang7, Lingling Geng1, Weizhou Zhang10, Jian Li6, Jie Qiao5, Tao Xu1,2, Jing Qu2,3 and Guang-Hui Liu1,2,8,11
Visualization of specific genomic loci in live cells is a prerequisite for the investigation of dynamic changes in chromatin architecture during diverse biological processes, such as cellular aging. However, current precision genomic imaging methods are hampered by the lack of fluorescent probes with high specificity and signal-to-noise contrast. We find that conventional transcription activator-like effectors (TALEs) tend to form protein aggregates, thereby compromising their performance in imaging applications. Through screening, we found that fusing thioredoxin with TALEs prevented aggregate formation, unlocking the full power of TALE-based genomic imaging. Using thioredoxin-fused TALEs (TTALEs), we achieved high-quality imaging at various genomic loci and observed aging-associated (epi) genomic alterations at telomeres and centromeres in human and mouse premature aging models. Importantly, we identified attrition of ribosomal DNA repeats as a molecular marker for human aging. Our study establishes a simple and robust imaging method for precisely monitoring chromatin dynamics in vitro and in vivo.