Global 3′‐untranslated region landscape mediated by alternative polyadenylation during meiotic maturation of pig oocytes.

Alternative polyadenylation affects the length and composition of 3′‐untranslated region (3′‐UTR) and regulates mRNA stability or translational activity to affect important biological processes. However, global 3′‐UTR landscape and its relationship with gamete maturation remain less studied. Here, we analysed our previously reported single‐cell RNA‐seq data of germinal vesicle and metaphase II stage oocytes in pigs to systematically catalogue the 3′‐UTR dynamics during oocyte maturation. Two softwares (DaPars and APAtrap) were employed and identified 110 and 228 mRNAs with significantly different 3′‐UTRs (adjusted p ≤.05), respectively. Gene enrichment analyses found signalling pathways related with biological processes of female gametophyte production, methyltransferase activity and mRNA surveillance (DaPars) and cell cycle process, regulation of ERK1 and ERK2 cascade, regulation of translation, spindle organization, kinetochore, condensed chromosome and progesterone‐mediated oocyte maturation (APAtrap), respectively. Moreover, 18 of 110 mRNAs (|△PDUI| ≥ 0.25 and |log2PDUI ratio| ≥ 0.59) and 15 of 228 mRNAs (Perc. diff. ≥ 0.5) were with greater difference of 3′‐UTR length or abundance, and integrative genomics viewer analysis further identified 4 (Alg10, Hadhb, Hsd17b4 and Sbds) of 18 mRNAs to be with 3′‐UTR length differed ≥150 bp and 6 (Gcc1, Hnrnpa2b1, Lsm6, Prpf18, Sfr1 and Ust) of 15 mRNAs to be with 3′‐UTR abundance extremely differed. Furthermore, the location, sequences and number of cis‐elements were predicted, which were shown to derange cytoplasmic polyadenylation element, poly(A) site and microRNA binding sites within 3′‐UTRs of Alg10, Hadhb, Hsd17b4 and Sbds mRNAs. Taken together, global 3′‐UTR landscape changes dynamically with oocyte meiotic maturation, potentially involved in regulating oocyte meiotic process in pigs. [ABSTRACT FROM AUTHOR]