Wherefore art thou, YY1

In this issue, Taguchi et al. demonstrate that the transcription factor Yin Yang-1 (YY1) regulates proliferation in three-dimensional cultures of the HaCaT human keratinocyte cell line. HaCaT keratinocytes overexpressing YY1 form artificial epidermal constructs that are thicker than those produced from vector-transfected cells. RNA interference-mediated YY1 knockdown decreases the thickness of YY1-overexpressing constructs, indicating that YY1 mediates the thickening. In primary keratinocytes, overexpressed YY1 also inhibits differentiation marker expression induced by calcium, supporting the idea that YY1 is important in regulating epidermal structure and function.