Submitted March 9, 2004
Returned for revision April 9, 2004
Accepted June 1, 2004
Mechanisms of Hormone Action
Independent Downstream Gene Expression Profiles in the
Presence of Estrogen Receptor 
or 
A. G.B. Hurst ,
D. W. Goad ,
M. Mohan ,
and
J. R. Malayer *
* To whom correspondence should be addressed. E-mail: malayer{at}okstate.edu.
Abstract
The two known forms of estrogen receptor (ER), 
and 
, exhibit differences in structure, affinity
for certain ligands, and tissue distribution, suggesting
differential roles. It is of interest from several
perspectives to determine whether the two receptors elicit
similar or differing responses within the same cell type
in the presence of the same ligand. To evaluate roles of
ER we have examined responses to estrogen in a rat
embryonic fibroblast cell line model, normally naive to
ER, engineered to stably express ER or ER.
Rat1+ER, Rat1+ER, and precursor Rat1 cell
lines were treated with estradiol-17
(E2; [1 nM]) or an ethanol vehicle for 24
hours. Total RNA was extracted, and cDNA generated and
subjected to suppression subtractive hybridization (SSH),
followed by differential screening using dot blot
hybridization. In the presence of ER products
were identified that represent classic responses to
E2, including markers for cell proliferation.
In the presence of ER an alternate transcription
profile was observed, including upregulation of
pro-alpha-2(I) collagen. These data support a model in
which ER and ER regulate unique subsets of
downstream genes within a given cell type.
Key words:
Mechanisms of Hormone Action •
Estradiol receptor •
Steroid hormone receptors
