We report here the study of the human CYP11A1 promoter in driving tissue-sp
ecific, developmentally and hormonally regulated reporter gene expression.
A 4.4-kb fragment containing all known regulatory elements is more efficien
t than a short basal promoter fused to an upstream adrenal enhancer in driv
ing reporter LacZ gene expression both in cell culture and in transgenic mi
ce. The LacZ gene controlled by the 4.4- and 2.3-kb promoters was expressed
in the adrenal cortex, testicular Leydig cells, ovarian corpora lutea, and
granulosa cells. Transgene expression in the adrenals was stimulated by AC
TH, indicating the presence of ACTH-responsive sequence. beta-Galactosidase
activity was first detected in the adrenal primordia at 11.5 days postcoit
um. Its expression continued throughout all stages of adrenal development i
n a pattern similar to that of the endogenous CYP11A1, which was expressed
in all zones of the adrenal cortex, but was strongest in the X zone. The X
zone grew before puberty but regressed afterward, as did the levels of CYP1
1A1 and LacZ gene expression in the X zone. Our study of the CYP11A1 promot
er in transgenic mice led to characterization of the adrenocortical zones.