Single cell RNA-seq Analysis of Wild Type(WT), Dcaf11 knockout(KO) and Dcaf11 knockdown(KD) embryos

Telomeres play vital roles in ensuring chromosome stability and are thus closely linked with the onset of aging and human disease. Telomeres undergo extensive lengthening during early embryogenesis through the so-called alternative lengthening of telomere (ALT) mechanism. However, the detailed molecular mechanism of telomere resetting in early embryos remains unknown. Here, we showed that Dcaf11 participates in telomere elongation in early embryos and 2-cell-like embryonic stem cells (ESCs) in a telomerase-independent manner. The deletion of Dcaf11 in embryos and ESCs leads to reduced telomere sister-chromatid exchange (T-SCE) and impairs telomere lengthening. Importantly, Dcaf11-deficient mice exhibit gradual telomere erosion with successive generations, and hematopoietic stem cell (HSC) activity is greatly compromised. Mechanistically, DCAF11 reactivates Zscan4 and facilitates the removal of heterochromatic H3K9me3 at telomere/subtelomere regions through targeting TRIM28 for ubiquitination-mediated degradation. Our study therefore demonstrates that the ALT factor Dcaf11 plays important roles in telomere elongation in early embryos and ESCs. We tested the transcriptome of ESC of WT and Dcaf11 KD ESC , and late 2-cell (hCG 36hr) embryos from WT and Dcaf11 KO mice using the Covaris DNA shearing protocol for Smart-seq sequence library generation. We found that the activation of Dux is important but not essential for ZGA, but the silencing and elimination of Dux is strictly necessary for early embryonic development. Embryos mRNA profiles of WT, Dcaf11 KO and Dcaf11 KD were generated by deep sequencing.