Tripartite Motif Containing Protein 40 (TRIM40)

The mouse Rnf35 gene is bi-exonic in structure and is transcribed in the preimplantation embryo until it is permanently silenced at the blastocyst stage of development. Rnf35 transcription is positively regulated by the nuclear factor Y. Rnf35 promoter was negatively modulated by a cis-cognate repressor element, designated as the downstream exon 1 repressor, or DER, residing between +72 and +95 in the untranslated exon 1 of the Rnf35 gene. Transcription of the Cdp gene was shown to first occur between the eight-cell and the blastocyst stages, correlating and possibly explaining the onset of Rnf35 silencing at the blastocyst stage. The evolutionarily acquired exon 1 of Rnf35, and possibly exon 1 of other similarly structured bi-exonic early embryonic genes, contributes to transcriptional modulation and silencing in the developing mouse embryo.