Selective binding of retrotransposons by ZFP352 facilitates the timely dissolution of totipotency network

Acquisition of new stem cell fates relies on the dissolution of the prior regulatory network sustaining the existing cell fates. Currently, extensive insights have been revealed for the totipotency regulatory network around the zygotic genome activation (ZGA) period. However, how the dissolution of the totipotency network is triggered to ensure the timely embryonic development following ZGA is largely unknown. In this study, we identified the unexpected role of a highly expressed 2C embryo specific transcription factor, ZFP352, in facilitating the dissolution of the totipotency network. We found that ZFP352 has bifurcated binding and regulation towards two different retrotransposon sub-families. ZFP352 coordinates with DUX to bind and regulate the 2C specific MT2_Mm sub-family. On the other hand, without DUX, ZFP352 switched affinity to bind extensively onto SINE_B1/Alu sub-family. This leads to the activation of later developmental programs like ubiquitination pathways, to facilitate the dissolution of the 2C state. Correspondingly, depleting ZFP352 in mouse embryos impaired the 2C to morula transition process. Thus, through differential regulation of MT2_Mm and SINE_B1/Alu, ZFP352 can trigger spontaneous dissolution of the totipotency network. Our study highlights the importance of different retrotransposons sub-families in facilitating the timely and programmed cell fates transition during early embryogenesis. (1) Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for ZFP352 protein of input and Zfp352 over expression samples (2) We then performed gene expression clustering analysis using data obtained from RNA-seq of 0h,12h,24h,36h,48h,72h samples after Dux over expression (3) Chromatin immunoprecipitation DNA-sequencing (ChIP-seq) for ZFP352 protein of Zfp352 over expression sample and Zfp352+Dux over expression sample (4) Chromatin immunoprecipitation DNA-sequencing (ATAC-seq) for ZFP352 protein of Zfp352 over expression sample and Zfp352+Dux over expression sample (5) RNAseq analysis using siRNA targeting Zfp352 in embryo at D2,D3,D4