Repeated stress suppresses interferon-gamma production by murine intestinal intraepithelial lymphocytes.

Intestinal intraepithelial lymphocytes (IEL), one of the major effector components in the mucosal immune system, are phenotypically and functionally distinct from thymic and peripheral T cells. To investigate the effect of repeated stress on the number and function of IEL, we exposed male C3H/HeN mice to mild electric foot shock for 30 min/day for 5 consecutive days. Immediately after the final foot shock stress, the blood, spleen, thymus and small intestine of each of the mice were obtained.

Membrane estrogen receptor-alpha levels in MCF-7 breast cancer cells predict cAMP and proliferation responses.

Introduction: 17beta-estradiol (E2) can rapidly induce cAMP production, but the conditions under which these cAMP levels are best measured and the signaling pathways responsible for the consequent proliferative effects on breast cancer cells are not fully understood. To help resolve these issues, we compared cAMP mechanistic responses in MCF-7 cell lines selected for low (mERlow) and high (mERhigh) expression of the membrane form of estrogen receptor (mER)-alpha, and thus addressed the receptor subform involved in cAMP signaling.

Methods: MCF-7 cells were immunopanned and subsequently separated by fluorescence activated cell sorting into mERhigh (mER-alpha-enriched) and mERlow (mER-alpha-depleted) populations.

Quantitative measurement of estrogen-induced ERK 1 and 2 activation via multiple membrane-initiated signaling pathways.

Estradiol (E2) and other steroids have recently been shown to initiate various intracellular signaling cascades from the plasma membrane, including those stimulating mitogen-activated protein kinases (MAPKs), and particularly extracellular-regulated kinases (ERKs). In this study we demonstrated the ability of E2 to activate ERKs in the GH3/B6/F10 pituitary tumor cell line, originally selected for its enhanced expression of membrane estrogen receptor-alpha (mERalpha). We compared E2 to its cell-impermeable analog (E2 conjugated to peroxidase, E2-P), and to the synthetic estrogen diethylstilbestrol (DES).

Proteins of multiple classes may participate in nongenomic steroid actions.

Responses to steroids initiated from non-nuclear receptors impinge on a wide variety of cellular responses and utilize nearly all known signal transduction webs. While the mechanisms by which steroid receptors localize in the membrane are still unclear, it is apparent that this alternative localization allows steroid receptors to participate in a wide range of complex functions influencing cell proliferation, death, and differentiation. The central debate still remains the identity of the protein class or classes that mediate membrane-initiated (nongenomic) responses.

Regulation of the membrane estrogen receptor-alpha: role of cell density, serum, cell passage number, and estradiol.

We used modified immunocytochemical conditions to quantify a membrane form of estrogen receptor-alpha (mERalpha) in a rat pituitary tumor cell line, GH3/B6/F10. We studied the regulation of mERalpha vs. levels of intracellular ERalpha (iERalpha) using our 96-well plate immunoassay.

Correlation of membrane glucocorticoid receptor levels with glucocorticoid-induced apoptotic competence using mutant leukemic and lymphoma cells lines.

We have studied the presence and functional implications of membrane glucocorticoid receptor (mGR) in several wild type (WT) and mutant mouse lymphoid cell lines (nuclear transfer decrease, NT(-); nuclear transfer increase, NT(i); and receptorless, R(-)). Direct fluorescent antibody staining revealed large aggregates of mGR-specific fluorescing antigens in the plasma membrane of the WT and mGR-enriched (mGR(++)) S-49 cells. While R(-) cells totally lacked mGR, this receptor level was low in NT(-) and NT(i) groups.

The dynamic and elusive membrane estrogen receptor-alpha.

Many studies have demonstrated the nuclear forms of steroid receptors and their activities, while fewer investigators have identified and described the membrane forms of these receptors. Our immuno-identification approaches for the qualitative and quantitative comparison of the membrane form of the estrogen receptor-alpha (mER alpha) to its nuclear counterpart now allow us to address questions about the comparative levels and regulation of these receptor forms. ER alpha-specific antisense oligonucleotides eliminate mER alpha expression, while only mildly reducing the nuclear ER alpha.