Antisense RNA directed against the 3' noncoding region prevents dormant mRNA activation in mouse oocytes.

Primary mouse oocytes contain untranslated stable messenger RNA for tissue plasminogen activator (t-PA). During meiotic maturation, this maternal mRNA undergoes a 3'-polyadenylation, is translated, and is degraded. Injections of maturing oocytes with different antisense RNA's complementary to both coding and noncoding portions of t-PA mRNA all selectively blocked t-PA synthesis. RNA blot analysis of t-PA mRNA in injected, matured oocytes suggested a cleavage of the RNA.RNA hybrid region, yielding a stable 5' portion, and an unstable 3' portion. In primary oocytes, the 3' noncoding region was susceptible to cleavage, while the other portions of the mRNA were blocked from hybrid formation until maturation occurred. Injection of antisense RNA complementary to 103 nucleotides of its extreme 3' untranslated region was sufficient to prevent the polyadenylation, translational activation, and destabilization of t-PA mRNA. These results demonstrate a critical role for the 3' noncoding region of a dormant mRNA in its translational recruitment during meiotic maturation of mouse oocytes.