Meric F, Searfoss A M, Wormington M, Wolffe A P
Laboratory of Molecular Embryology, NICHD, National Institutes of Health, Bethesda, Maryland 20892-5431, USA.
J Biol Chem. 1996 Nov 29;271(48):30804-10. doi: 10.1074/jbc.271.48.30804.
We establish that masked mRNAs synthesized from exogenous plasmid templates microinjected into the nuclei of Xenopus oocytes are translationally activated (unmasked) on oocyte maturation concomitant with polyadenylation. Synthetic mRNA injected into the cytoplasm of the oocyte is translated over an order of magnitude more efficiently than is the cognate mRNA synthesized in vivo. Both mRNA synthesized in vivo and mRNA microinjected into the oocyte cytoplasm require a cytoplasmic polyadenylation element in the 3'-untranslated region to activate translation on maturation. Although polyadenylation upon oocyte maturation can relieve the translational repression of mRNA synthesized in vivo, the excision of an intron within the nucleus does not relieve repression. We suggest that the translational repression coupled to the transcription process will more effectively repress inappropriate gene expression in the oocyte and offer the potential to achieve a wider range of gene regulation.
我们证实，将外源性质粒模板微注射到非洲爪蟾卵母细胞核中合成的掩蔽mRNA，在卵母细胞成熟并伴随多聚腺苷酸化时会被翻译激活（去掩蔽）。注射到卵母细胞细胞质中的合成mRNA的翻译效率比体内合成的同源mRNA高一个数量级以上。体内合成的mRNA和微注射到卵母细胞细胞质中的mRNA都需要3'非翻译区中的细胞质多聚腺苷酸化元件来激活成熟时的翻译。虽然卵母细胞成熟时的多聚腺苷酸化可以解除体内合成的mRNA的翻译抑制，但细胞核内内含子的切除并不能解除抑制。我们认为，与转录过程相关的翻译抑制将更有效地抑制卵母细胞中不适当的基因表达，并提供实现更广泛基因调控的潜力。
