Regulation of RNA polymerase I transcription in response to F9 embryonal carcinoma stem cell differentiation

Dramatic changes in the patterns of transcription are a common feature of early development, We have used F9 embryonal carcinoma cells as a model system to study gene regulation during an early stage of murine embryogenesis, We find that transcription by RNA polymerase I decreases when F9 cells differentiate into parietal endoderm, The reduced rate of transcription is associated with a down-regulation of several components of the Glass I transcription apparatus. The most substantial change involves the essential factor SL1, which is a multisubunit complex that contains the TATA-binding protein and three TATA-binding protein-associated factors (TAFs), The abundance of two of these TAFs, TAAF(I)48 and TAF(I)95, decreases during F9 cell differentiation. Developmental regulation of a specific class of genes may therefore be achieved through changes in the availability of TAFs.