N. Kagawa et al., A CAMP-REGULATORY SEQUENCE (CRS1) OF CYP17 IS A CELLULAR TARGET FOR THE HOMEODOMAIN PROTEIN PBX1, The Journal of biological chemistry, 269(29), 1994, pp. 18716-18719
Cytochrome P450c17 encoded by CYP17, whose expression is regulated by
peptide hormones via cAMP, is required for cortisol and sex hormone bi
osynthesis thereby playing a key role in biological processes includin
g sexual differentiation. Utilizing the cAMP-regulatory sequence CRS1
of the bovine CYP17 gene as an affinity ligand, four CRS1-binding prot
eins have been purified from nuclear extracts of mouse adrenocortical
Y1 cells and shown to enhance the in vitro transcription of a reporter
gene promoted by CRS1. Microsequencing of these four proteins establi
shed two of them to be the homeodomain proteins Pbx1a and Pbx1b, origi
nally discovered by their involvement in the t(1;19) chromosomal trans
location in pre-B-cell acute lymphoblastic leukemias. Overexpression o
f Pbx1 in Y1 cells enhances cAMP-dependent transcription of the CRS1-d
ependent reporter gene. These results identify the CRS1 of bovine CYP1
7 as a cellular target for Pbx1 and suggest that one role of this home
odomain protein is in the regulation of steroidogenesis and subsequent
ly sexual development.