GSE111152
Maternal mRNA degradation by TUT4 and TUT7 in the zebrafish maternal-to-zygotic transition
During the maternal-to-zygotic transition (MZT), maternal RNAs are actively degraded and replaced by newly-synthesized zygotic transcripts in a highly coordinated manner. However, it remains largely unknown how maternal mRNA decay is triggered in early vertebrate embryos. Here, through genome-wide profiling of RNA abundance and 3' modification, we show that uridylation is induced at the onset of maternal mRNA clearance. The temporal control of uridylation is conserved in vertebrates. When the homologs of terminal uridylyltransferases TUT4 and TUT7 (TUT4/7) are depleted in zebrafish and Xenopus, maternal mRNA clearance is significantly delayed, leading to developmental defects during gastrulation. Short-tailed mRNAs are selectively uridylated by TUT4/7, with the highly uridylated transcripts degraded faster during the MZT than those with unmodified poly(A) tails. Our study demonstrates that uridylation plays a crucial role in timely mRNA degradation, thereby allowing the progression of early development. Overall design: Examination of zebrafish embryos injected with control or TUT4/7 morpholinos at 1-cell stage. RNA-seq libraries were prepared at different time points across the MZT period. Three experimental sets, rs1a, rs2b, and rs2,  were conducted independently.