Polyadenylation of mRNAs encoding secreted proteins by TENT5 family of enzymes is essential for gametogenesis in mice.

Cytoplasmic polyadenylation plays a vital role in gametogenesis, however, the participating enzymes and substrates in mammals remain unclear. Using knockout and knock-in mouse models, we describe the essential role of 4 TENT5 poly(A) polymerases in mice fertility and gametogenesis. TENT5B and TENT5C play crucial, but redundant roles in oogenesis, with double knockout of both genes leading to oocyte degeneration. Additionally, TENT5B-GFP knock-in females display gain-offunction infertility effect with multiple chromosomal aberrations in ovulated oocytes. TENT5C and TENT5D both regulate different stages of spermatogenesis, shown by sterility of males with either gene's knockout mutation. Finally, Tent5a knockout significantly lowers fertility, although the underlying mechanism is not directly related to gametogenesis. Through Direct RNA sequencing we discovered that TENT5s polyadenylate mRNAs encoding endoplasmic reticulum-targeted proteins essential for gametogenesis. Sequence motives analysis and reporter mRNA assay revealed that the presence of endoplasmic reticulum-leader represents the primary determinant of TENT5-mediated regulation.