ERα and ERK1/2 MAP kinase expression in microdissected stromal and epithelial endometrial cells

Abstract

Our previous published data detected higher expression of total and active mitogen activated protein kinase (MAPK) in the epithelial vs. stromal cells of the endometrium. In the present work we compared the expression of ERK1/2 MAPK and estrogen receptor α (ERα) in epithelial versus stromal cells in benign human endometrial tissues. Laser capture microdissection was used to separate glandular epithelium and stromal cells from six frozen, proliferative phase endometrial specimens. Total and phosphorylated levels for ERK1/2 and ERα were measured by quantitation of signals from Western blots using specific antibodies against the active and total forms of ERK1/2 and against ERα. When the level of the proteins was quantitated and normalized to β actin from microdissected stroma and epithelium, no significant difference was detected in the levels of these proteins between the two tissue compartments. There was a trend toward higher expression in the stroma vs. epithelium, respectively (active ERK1/2 0.45 ± 0.17 vs. 0.2 ± 0.65; total ERK1/2 0.54 ± 0.35 vs. 0.28 ± 0.23; ERα 0.82 ± 0.28 vs. 0.54 ± 0.18; n=6). These data demonstrate that there are comparable levels of ERα (P=0.41), total ERK1/2 (P=0.18) and active ERK1/2 (P=0.13) in the stroma and epithelium of proliferative phase endometrium with a trend toward higher expression of these proteins in the stromal compartment.

Placental development during early pregnancy in sheep: nuclear estrogen and progesterone receptor mRNA expression in the utero-placental compartments

“…Furthermore, microarray analysis of compartments collected using LCM has demonstrated that expression of genes was greater in LE than EG, and that LE and EG exhibit distinct genetic signatures in mouse uteri [20]. Similar to our results, level of ESR1 mRNA expression did not differ in human EG and ES dissected using LCM at proliferative phase of the estrous cycle [24]. Observed differences in the level of expression among uterine compartments are likely due to methods applied and species studied.…”

“…Differential expression of mRNA for selected genes in uterine or placental compartments has been demonstrated by others for sheep [13,23], humans [18,24], rhesus monkeys [15], and mouse [16,19,20,25]. In situ hybridization studies have shown that mRNA expression for ESR and PGR differed in LE, EG, ES and MYO depending on reproductive status (e.g., non-pregnant, pregnant or ovariectomized) in sheep [13,26].…”

Inside the Endometrial Cell Signaling Subway: Mind the Gap(s)

“…Moreover, E2-nER transcription induces insulin-like growth factor 1 (IGF-1) and mitogen-activated protein kinase (MAPK) pathway related genes [ 24 , 25 , 26 ]. In a positive feedback, IGF-1 and MAPK cascades are involved in the nongenomic ER-dependent and -independent regulation of E2-driven proliferation [ 27 , 28 ]. In this context, the most well characterized nongenomic model of ER action is mediated through the activation of IGF-1 receptor (IGF-1R).…”

“…The pathway can also induce phosphorylation of nER, which upon dimerization and translocation to the nucleus will initiate transcription of MAPK related genes, notably in an E2-independent manner [ 32 ]. ER, total and activated ERK1/2 kinase levels are seemingly comparable in stroma and epithelium of the proliferative endometrium, suggesting pathway activity in both compartments [ 28 ]. The PI3K/Akt pathway, on the other hand, results from phosphorylation of the endocytic regulator insulin receptor substrate 1 (IRS-1).…”