Translation of maternal messenger ribonucleic acids encoding transcription factors during genome activation in early mouse embryos.
Embryonic genome activation (EGA) in mice is sensitive to treatment with cycloheximide, indicating that protein synthesis plays an important role in mediating EGA. We hypothesized that regulated maternal mRNA recruitment may control the time of EGA by controlling the time of appearance of certain transcription factors (TFs). We also hypothesized that synthesis of other TFs may contribute to EGA independently of controlling the timing of EGA. To test these hypotheses, we used sucrose density gradient fractionation coupled to a quantitative reverse transcription-polymerase chain reaction method to compare polysomal mRNA abundances of specific TF mRNAs between metaphase II oocytes, 1-cell-stage embryos, and 2-cell-stage embryos. We observed a 2-cell-stage-specific increase in polysomal abundance of mouse TEA DNA binding domain 2 (mTEAD-2) mRNA, coincident with the first appearance of mTEAD activity in the early embryo. The mRNAs encoding Sp1, TATA binding protein, and cyclic AMP response element binding protein did not undergo translational recruitment, but exhibited differences in polysomal abundance. We also observed a continuous, high proportion in the polysomal fraction for the mRNA encoding ribosomal protein L23 mRNA, which contrasted with the patterns observed for other maternal transcripts. These observations are consistent with the hypothesis that regulated recruitment of maternal TF mRNAs may control the time of activation of some genes during EGA, and that continuous synthesis of other TFs, like Sp1, may facilitate EGA.
Wang
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The Fels Institute for Cancer Research and Molecular Biology and Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
Latham
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KE
D000818:Animals; D017362:Cyclic AMP Response Element-Binding Protein / Q000096:biosynthesis / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D004622:Embryo, Mammalian / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D015894:Genome, Human; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D009865:Oocytes; D011132:Polyribosomes / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000096:biosynthesis / Q000235:genetics; D016385:TATA Box / Q000235:genetics; D035181:TATA-Box Binding Protein; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D035181:TATA-Box Binding Protein; D000091262:TEA Domain Transcription Factors; C101205:TEAD2 protein, human; C486310:Tead2 protein, mouse; D014157:Transcription Factors