Tc. Pappas et al., MEMBRANE ESTROGEN RECEPTOR-ENRICHED GH(3) B6 CELLS HAVE AN ENHANCED NON-GENOMIC RESPONSE TO ESTROGEN/, Endocrine, 3(10), 1995, pp. 743-749
We immunoselected CH3/B6 cells for a membrane estrogen receptor (mER)
using antibodies generated against the rat intracellular ER (iER). Imm
unocytochemistry with anti-ER antibodies revealed bright fluorescence
distributed in patches over the surface of mER-enriched cells, while c
ells immune-depleted for mER showed only low-level membrane immunofluo
rescence. Quantitation via digital image analysis confirmed that immun
o-enriched populations show increases in both stained cell numbers and
intensity of staining. Short-term culturing with serum reversibly dec
reased the intensity of immunostaining in mER-enriched cells to immune
-depleted cell levels. The mER-enriched populations initially containe
d similar to 85% immunopositive cells in defined medium, but when cult
ured continuously with serum gradually decline to similar to 22% immun
opositive cells by 10 weeks. Cells enriched for mER showed a significa
nt increase in rapid (after 2 or 5 min) prolactin release when treated
with 17 beta-estradiol, while mER-depleted cells lacked this response
. Immunoprecipitable membrane proteins isolated from mER-enriched cell
s were 60,000, 74,000 and similar to 200,000 MW, compared to an iER si
ze of 67,000. Therefore, the presence and level of an mER that is anti
genically related to iER is correlated with the ability of GH(3)/B6 ce
lls to mediate a rapid action of estrogen.