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Regulation of gene expression in the preimplantation mouse embryo: Temporal and spatial patterns of expression of the transcription factor Sp1
Author(s) -
Worrad Diane M.,
Schultz Richard M.
Publication year - 1997
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/(sici)1098-2795(199703)46:3<268::aid-mrd5>3.0.co;2-n
Subject(s) - biology , inner cell mass , blastocyst , reprogramming , embryo , transcription factor , sp1 transcription factor , gene expression , maternal to zygotic transition , oocyte , microbiology and biotechnology , embryogenesis , regulation of gene expression , genetics , gene , andrology , zygote , promoter , medicine
Activation of the embryonic genome during preimplantation mouse development entails a dramatic reprogramming of the pattern of gene expression. The complement of transcription factors that are present in the early embryo and that must intrinsically be involved in this reprogramming is essentially uncharacterized. We and others have demonstrated that transcription factor Sp1 is present in the mouse oocyte and early cleavage stage preimplantation embryo. Due to Sp1's prominent role in regulating the expression of a vast array of genes that are involved in cell proliferation and differentiation, as well as in general housekeeping functions, we characterized the temporal and spatial patterns of Sp1 expression during preimplantation development. The relative abundance of Sp1 transcripts, as well as transcripts for the TATA box‐binding protein TBP, decreases during oocyte maturation and reaches a minimum level in the two‐cell stage, after which time the abundance of these transcripts increases progressively to the blastocyst stage. Immunoblotting experiments detect Sp1 species of M r = 95,000 and 105,000 at all stages of preimplantation development. The amount of Sp1 increases about 8‐fold during preimplantation development, and an α‐amanitin‐insensitive increase is observed between G1 and G2 of the one‐cell embryo; this increase may reflect the mobilization of a maternal Sp1 transcript. Immunocytochemical experiments also reveal a similar increase in the amount of Sp1 during preimplantation; the nuclear concentration of Sp1 is greater in the trophectoderm cells than in the inner cell mass cells. Finally, gel‐shift experiments document an increase during preimplantation development of a DNA‐binding activity that is likely due to Sp1. These increases in the abundance of the Sp1 protein and an Sp1‐like DNA‐binding activity parallel increases in the rate of transcription that occur during preimplantation development. Mol. Reprod. Dev. 46:268–277, 1997. © 1997 Wiley‐Liss, Inc.