Yin-Yang1 is required for epithelial-to-mesenchymal transition and regulation of Nodal signaling during mammalian gastrulation.

The ubiquitously expressed Polycomb Group protein Yin-Yang1 (YY1) is believed to regulate gene expression through direct binding to DNA elements found in promoters or enhancers of target loci. Additionally, YY1 contains diverse domains that enable a plethora of protein-protein interactions, including association with the Oct4/Sox2 pluripotency complex and Polycomb Group silencing complexes. To elucidate the in vivo role of YY1 during gastrulation, we generated embryos with an epiblast specific deletion of Yy1.

Yin-yang1 is required in the mammalian oocyte for follicle expansion.

The multifaceted polycomb group gene Yin-Yang1 (Yy1) has been implicated in a variety of transcriptional regulatory roles both as an activator and silencer of gene expression. Here we examine the role of Yy1 during oocyte growth by conditional deletion of the locus in the growing oocyte. Our results indicate that YY1 is required for oocyte maturation and granulosa cell expansion.

Complexity of polycomb group function: diverse mechanisms of target specificity.

Epigenetic regulation of gene expression has become relevant to nearly all areas of biomedical research. The emergence of technologies that allow for examination of the epigenome combined with identification of key protein complexes that mediate the myriad chromatin modifications that occur have greatly enhanced the versatility and efficacy of tools with which to study normal development and disease states. The evolutionarily conserved polycomb group genes (PcG) have been identified as a predominant mechanism by which gene silencing occurs during development, differentiation, and disease.

Identification of novel oocyte and granulosa cell markers.

Here we present novel gene expression patterns in the ovary as part of an ongoing assessment of published micro-array data from mouse oocytes and embryos. We present the expression patterns of 13 genes that had been determined by micro-array to be expressed in the mature egg, but not during subsequent preimplantation development. In-situ hybridization of sectioned ovaries revealed that these genes were expressed in one of two distinct patterns: (1) oocyte-specific or (2) expressed in both the oocyte and surrounding granulosa cells.