Contributions of steroidogenic factor 1 to the transcription landscape of Y1 mouse adrenocortical tumor cells.

The contribution of steroidogenic factor 1 (SF-1) to the gene expression profile of Y1 mouse adrenocortical cells was evaluated using short hairpin RNAs to knockdown SF-1. The reduced level of SF-1 RNA was associated with global changes that affected the accumulation of more than 2000 transcripts. Among the down-regulated transcripts were several with functions in steroidogenesis that were affected to different degrees--i.e.， Mc2r>Scarb1>Star≥Hsd3b1>Cyp11b1. For Star and Cyp11b1， the different levels of expression correlated with the amount of residual SF-1 bound to the proximal promoter regions. The knockdown of SF-1 did not affect the accumulation of Cyp11a1 transcripts even though the amount of SF-1 bound to the proximal promoter of the gene was reduced to background levels. Our results indicate that transcripts with functions in steroidogenesis vary in their dependence on SF-1 for constitutive expression. On a more global scale， SF-1 knockdown affects the accumulation of a large number of transcripts， most of which are not recognizably involved in steroid hormone biosynthesis.