Broad tissue expression of membrane progesterone receptor Alpha in normal mice

Atlanta VA Medical Center, Decatur, GA 30033, USA.
Journal of molecular histology (Impact Factor: 1.82). 04/2010; 41(2-3):101-10. DOI: 10.1007/s10735-010-9265-7
Source: PubMed


The broad tissue distribution of membrane progesterone receptor alpha (mPRalpha) in vertebrates suggests multiple physiological functions of the receptor. Current knowledge regarding the receptor distribution, however, is largely obtained via non-histological assays. In this study, the tissue distribution of mPRalpha in mice of both sexes was described using both histological and non-histological methods. Immunohistochemical analysis revealed that abundant expression of mPRalpha was consistently detected in the cytoplasm and membrane of smooth muscles in vasculatures, gastro-intestines, and uterus. It was also observed in myoepithelial cells of mammary gland and intra-ovarian myofibroblasts. These findings suggest that mPRalpha may function as a mediator of P4 in regulating function of smooth muscles or smooth muscle-like cells in numerous physiological processes such as vasodilation, transportation of contents within luminary organs, relaxation of the uterine myometrium during pregnancy, release of oocytes, and milk secretion. In addition, strong mPRalpha expression was identified in the parietal cells of gastric glands, indicating the potential roles of P4/mPRalpha signaling in the modulation of gastric acid secretion. Surprisingly, in the testis of male mice mPRalpha was mainly seen in the nuclei, rather than cytoplasm and/or membrane, of the primary and secondary spermatocytes, suggesting a direct role of the receptor in gene regulation. Our results indicate that mPRalpha may function as a key modulator of P4 in the modulation of multiple physiological functions in normal mice.

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    • "The color was developed with the ImmPACT DAB kit (VECTOR Lab, Burlingame, CA, USA). Between the incubations, the slides were washed twice with 1× PBS buffer (5 minutes each) [19,22]. Two negative controls were included: (1) control slides were stained without the primary antibody; (2) control slides were incubated with a specific blocking peptide (cat# sc-50111p, Santa Cruz, CA, USA) prior to the primary antibody incubations. "
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    ABSTRACT: Basal phenotype breast cancers (BPBC) are often associated with apparent epithelial to mesenchymal transition (EMT). The role of progesterone (P4) in regulating EMT of BPBC has not been reported. The EMT relevant biology was investigated in vitro using human BPBC cell models (MDA-MB468 and MDA-MB231) with P4, PR agonist (RU486), and PR antagonist (R5020) treatments. The essential role of membrane progesterone receptor alpha (mPRalpha) in the P4-regulated EMT was demonstrated by knocking down the endogenous gene and/or stably transfecting exogenous mPRalpha gene in the BPBC cell models. The expression of snail and down-stream EMT proteins such as occludin, fibronectin, and E-cadherin was significantly regulated by P4 incubation, which was accompanied by cell morphological reversion from mesenchymal to epithelial phenotypes. In searching for the cell mediator of P4' action in the MDA-MB468 (MB468) cells, it was found that mPRalpha but not the nuclear PR has an essential role in the P4 mediated EMT inhibition. Knocking down the expression of mPRalpha with specific siRNA blocked the P4's effects on expression of the EMT proteins. In another BPBC cell line--MDA-MB231 (MB231), which is mPRalpha negative by Western blotting--P4 treatment did not alter cell proliferation and EMT protein expressions. Introduction of the exogenous mPRalpha cDNA into these cells caused cell proliferation, but not EMT, to become responsive to P4 treatment. In further studies, it was found that activation of the PI3K/Akt pathway is necessary for the P4-induced EMT reversion. To define the potential inter-mediate steps between mPRalpha and PI3K, we demonstrated that mPRalpha, caveolin-1 (Cav-1), and epidermal growth factor receptor (EGFR) are colocalized in the membrane of caveolar vesicle and the P4-repressed EMT in MB468 cells can be blocked by EGFR inhibitor (AG1478) and PI3K inhibitor (wortmannin). Our data suggest that the signaling cascade of P4 induced mesenchymal repression is mediated through mPRalpha and other caveolae bound signaling molecules namely Cav-1, EGFR, and PI3K. This novel finding may have great impact on fully understanding the pathogenesis of BPBC and provide an essential clue for developing a targeted therapeutic strategy for treatment of BPBC.
    Full-text · Article · Jun 2010 · Breast cancer research: BCR
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    ABSTRACT: Classically, the actions of progesterone (P4) are attributed to the binding of nuclear progesterone receptor (PR) and subsequent activation of its downstream target genes. These mechanisms, however, are not applicable to PR- or basal phenotype breast cancer (BPBC) due to lack of PR in these cancers. Recently, the function of membrane progesterone receptor alpha (mPRα) in human BPBC cell lines was studied in our lab. We proposed that the signaling cascades of P4→mPRα pathway may play an essential role in controlling cell proliferation and epithelial mesenchymal transition (EMT) of breast cancer. Using human breast cancer tissue microarrays, we found in this study that the average intensity of mPRα expression, but not percentage of breast cancer with high level of mPRα expression (mPRα-HiEx), was significantly lower in the TNM stage 4 patients compared to those with TNM 1-3 patients; and both average intensities of mPRα expression and mPRα-HiEx rates were significantly higher in cancers negative for ER, as compared with those cancers with ER+. However, after adjusting for age at diagnosis and/or TNM stage, only average intensities of mPRα expression were associated with ER status. In addition, we found that the rates of mPRα-HiEx were significantly higher in cancers with epithelial growth factor receptor-1 (EGFR+) and high level of Ki67 expression, indicating positive correlation between mPRα over expression and EGFR or Ki67. Further analysis indicated that both mPRα-HiEx rate and average intensity of mPRα expression were significantly higher in HER2+ subtype cancers (i.e. HER2+ER-PR-) as compared to ER+ subtype cancers. These data support our hypothesis that P4 modulates the activities of the PI3K and cell proliferation pathways through the caveolar membrane bound growth factor receptors such as mPRα and growth factor receptors. Future large longitudinal studies with larger sample size and survival outcomes are necessary to confirm our findings.
    Full-text · Article · Apr 2012 · PLoS ONE
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    ABSTRACT: OBJECTIVE:: To examine the influence of age and gender on the development of proximal gastric pouch distension (PPD) after laparoscopic adjustable gastric banding (LAGB) surgery. BACKGROUND:: PPD is the most common reason for revision with adjustable gastric banding surgery. Maintaining the anatomical integrity of bariatric surgery is a key to long-term success. It is therefore important to understand risk factors for complications. METHODS:: We extracted details of 3000 consecutive individuals who underwent primary LAGB procedures at a single center between February 2005 and May 2011. Contemporaneous details of all complications were recorded in a database. The characteristics of those that subsequently required revision surgery for PPD were assessed and compared with those that did not. RESULTS:: There were 132 cases for PPD requiring surgical intervention before September 2011. Incident PPD occurred in 5.1% and 1.3% of women and men, respectively. The mean age of those with PPD was 39.9 ± 9.25 compared with 43.9 ± 11.0 for those without it. The age and gender effects were independent, and the age effect was restricted to women. The adjusted odds ratios were 0.971 (95% CI [confidence interval], 0.954-0.986, P < 0.001) for age and 0.26 (95% CI, 0.12-0.56, P = 0.001) for male gender and younger women were more likely to have asymmetrical distension. CONCLUSIONS:: Younger women are at higher risk of PPD after LAGB surgery than men and women older than 50 years. Sex hormones may play a role in predisposing to gastric stretch after surgery. These findings may apply more broadly to the gastric "restrictive" component of other bariatric procedures.
    No preview · Article · Apr 2012 · Annals of surgery
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