Expression analysis of TFIID in single human oocytes: new potential molecular markers of oocyte quality.

Molecular characterization of human female gametes should make it easier to understand the basis of certain infertility disorders. Biologically significant mRNAs have been analysed in single oocytes to search for molecular biomarkers of oocyte quality. Initial analysis was focused on mRNA for proteins involved in cell growth and cycle control, specifically those encoding members of the general transcription apparatus such as the subunits of the general transcription factor TFIID. This heteromultimeric protein, comprising about 15 subunits, is the most important general transcription factor of the second class. These proteins are essential for the initiation of transcription of protein-coding genes, so they must be present in mature oocytes for mRNA synthesis during the first phases of embryonic development. Semi-quantitative reverse transcriptionpolymerase chain reaction was used to identify different TFIID subunits in single oocytes and to search for differences in expression as compared with control tissues. The data show that the mRNAs for most TFIID subunits are indeed synthesized in oocytes, but their expression profiles differ markedly. TATAbox-binding protein associated factor 4B (TAF4B), TAF5 and TATAbox-binding protein-like 2 (TBPL2) are expressed at higher levels in oocytes than in control tissues. It is suggested that they could be used as biomarkers of oocyte quality.