also revealed sequences at -249 and -148 that re- 
semble the sequence motifs at -210 and -65 in the 
21-OHase promoter region. However, mutagenesis 
of these elements showed that they do not play sig- 
nificant roles in lip-OHase expression. These stud- 
ies have thus identified three regulatory elements 
that play important roles in llp-OHase expression. 
Efforts are now under way to isolate and character- 
ize the proteins that interact with the two upstream 
elements. 
III. Side-Chain Cleavage Enzyme Gene Regulation. 
In a new direction, the laboratory recently 
cloned the mouse SCC gene and began to study its 
regulation. This gene is expressed by all steroido- 
genic tissues in a cAMP-responsive fashion. The pro- 
moter region of the SCC gene directed high levels 
of expression of a linked reporter gene after trans- 
fection into Yl adrenal cells; this expression was in- 
creased fourfold by treatment with 8-Br-cAMP. Sev- 
eral regions that are important for expression were 
localized by 5 '-deletion experiments, including the 
regions from -420 to -318 and from -200 to -75. 
DNase I footprinting experiments revealed several 
protein-DNA interactions. The sequence protected 
in one footprint, at -70, shares the AGGTCA motif 
found in the 21-OHase elements at -210 and -65. 
PUBLICATIONS 
A second element, at -42, is an inverted repeat of 
the central region of a 21-OHase regulatory ele- 
ment at -140. Roles of these elements in SCC ex- 
pression have not yet been demonstrated, and 
functional studies are in progress to address this 
issue. However, the importance of these motifs in 
21-OHase expression predicts that they may also 
play major roles in SCC expression. This would 
provide the first evidence for the model that shared 
regulatory elements are involved in coordinate reg- 
ulation of the steroidogenic enzymes. 
Collectively these studies have defined important 
regulatory elements that control the expression of 
the adrenal steroidogenic enzymes. Support for the 
model that shared elements mediate the coordinate 
expression of these genes is provided by the identi- 
fication of two elements that are present in the pro- 
moter regions of both 21-OHase and SCC. The suc- 
cessful isolation of the regulatory proteins that 
interact with these elements and the analysis of 
their regulation will provide insights into the mech- 
anisms that determine the complex regulation of 
this essential group of genes. 
Dr. Parker is also Assistant Professor of Medicine 
and of Biochemistry at Duke University Medical 
Center. 
Articles 
Parker, K.L., and Gwynne, J.L. 1988. Control of steroid hormone synthesis. In Textbook of Medicine (Kelley, 
WN., Ed.). Philadelphia, PA: Lippincott, pp 2120-2124. 
Articles 
Handler, J.D., Schimmer, B.P, Flynn, T.R., Szyf, M., Rice, D.A. , and Parker, K.L. 1989. Regulation of 21- 
hydroxylase gene expression. Endocr Res 15:31-47. 
Mouw, A.R. , Rice, D.A. , Meade, J.C. , Chua, S C., White, PC, Schimmer, B.R, and Parker, K.L. 1989. Structural 
and functional analysis of the promoter region of the gene encoding mouse steroid lip-hydroxylase. / 
Biol Chem 264:1305-1309. 
Rice, D.A., Aitken, L.D., Vandenbark, G.R., Mouw, A.R., Franklin, A., Schimmer, B.P, and Parker, K.L. 1989- A 
cAMP-responsive element regulates expression of the mouse steroid lip-hydroxylase gene. J Biol Chem 
264:14011-14015. 
Wong, M., Rice, D.A. , Parker, K.L. , and Schimmer, B.P 1989. The roles of cAMP and cAMP-dependent protein 
kinase in the expression of cholesterol side chain cleavage and steroid lip- hydroxylase genes in mouse 
adrenocortical tumor cells. J Biol Chem 264:12867-12871. 
98 
