RESUMO
We studied the developmentally regulated expression of mouse TFII-I, a founding member of a family of transcription factors characterized by the presence of multiple helix-loop-helix repeat domains. TFII-I and BEN, a second member of this family, are involved in histone modification and SUMOylation. The genes, GTF2I and GTF2IRD1, encoding these proteins in human are located at chromosomal band 7q11.23, within the Williams syndrome critical region. Our immunohistochemical analysis revealed extensive expression of TFII-I at early stages of embryogenesis. Like BEN, TFII-I is detected in the cytoplasm and nuclei of postfertilization through first cleavage stage embryos. However, in E4.5 blastocysts, at the time of implantation, TFII-I is localized in the nucleus and cytoplasm of the inner cell mass (ICM) and trophectoderm. BEN, at this stage, is expressed only in the cytoplasm of trophoblast cells, but not in the ICM [Gene Expr. Patterns, 2003; 3, 577-587]. Using RT-PCR, we detected Gtf2i and Gtf2ird1 mRNA transcripts in unfertilized oocytes, which indicates the maternal expression of these genes. Thus, the early embryonic expression of TFII-I implicates this family of transcription factors in preimplantation development.
Assuntos
Blastocisto/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Fatores de Transcrição TFII/genética , Animais , Imuno-Histoquímica , Camundongos , Microscopia de Fluorescência , Proteínas Musculares/genética , Proteínas Nucleares/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transativadores/genética , Fatores de Transcrição TFII/biossínteseRESUMO
BEN is a member of the TFII-I family of transcription factors, characterized by the presence of multiple helix-loop-helix repeat domains. Our immunohistochemical analysis demonstrated broad and extensive expression of BEN during mouse pre- and postimplantation development, with highest levels occurring during early to midgestation. Maternally expressed BEN is present in both the cytoplasm and nuclei of the zygote; however, it retains a predominantly nuclear localization between the two-cell stage of development and early blastocyst stages. This nuclear expression is observed in most tissues throughout development. Although, it is interesting to note that at E4.5-6.5, during early gastrulation stage, BEN is localized in the cytoplasm. At later stages, BEN retains an extensive expression pattern in a variety of developing systems implicating its involvement in tissue development and organogenesis.
