Steroid receptor coactivator 2 is required for female fertility and mammary morphogenesis: insights from the mouse, relevance to the human

Although the importance of the progesterone receptor (PR) to female reproductive and mammary gland biology is firmly established, the coregulators selectively co-opted by PR in these systems have not been clearly delineated. A selective gene-knockout approach applied to the mouse, which abrogates gene function only in cell types that express PR, recently disclosed steroid receptor coactivator 2 (SRC-2, also known as TIF-2 or GRIP-1) to be an indispensable coregulator for uterine and mammary gland responses that require progesterone. Uterine cells positive for PR (but devoid of SRC-2) were found to be incapable of facilitating embryo implantation, a necessary first step toward the establishment of the materno-fetal interface. Importantly, such an implantation defect is not exhibited by knockouts for SRC-1 or SRC-3, underscoring the unique coregulator importance of SRC-2 in peri-implantation biology. Moreover, despite normal levels of PR, SRC-1 and SRC-3, progesterone-dependent branching morphogenesis and alveologenesis fails to occur in the murine mammary gland in the absence of SRC-2, thereby establishing a critical coregulator role for SRC-2 in signaling cascades that mediate progesterone-induced mammary epithelial proliferation. Finally, the recent detection of SRC-2 in the human endometrium and breast suggests that this coregulator may represent a new clinical target for the future management of female reproductive health and/or breast cancer

Evaluation of Apoptosis and Autophagy Inducing Potential of Berberis aristata, Azadirachta indica, and Their Synergistic Combinations in Parental and Resistant Human Osteosarcoma Cells

Cancer is a multifactorial disease and hence can be effectively overcome by a multi-constituently therapeutic strategy. Medicinal plant extracts represent a perfect example of such stratagem. However, minimal studies have been done till date that portray the effect of extraction techniques on the phyto-constituent profile of plant extracts and its impact on anticancer activity. In the present study, we have evaluated the anticancer potential of methanolic extracts of Berberis aristata root and Azadirachta indica seeds prepared by various extraction techniques in human osteosarcoma (HOS) cells. Soxhlation extract of B. aristata (BAM-SX) and sonication extract of A. indica (AIM-SO) were most effective in inducing apoptosis in parental drug sensitive, as well as resistant cell type developed by repeated drug exposure. Generation of reactive oxygen species and cell cycle arrest preceded caspase-mediated apoptosis in HOS cells. Interestingly, inhibition of autophagy enhanced cell death suggesting the cytoprotective role of autophagy. Combination studies of different methanolic extracts of BAM and AIM were performed, among which, the combination of BAM-SO and AIM-SO (BAAISO) was found to show synergism (IC50 10.27 µg/ml) followed by combination of BAM-MC and AIM-MC (BAAIMC) with respect to other combinations in the ratio of 1:1. BAAISO also showed synergism when it was added to cisplatin-resistant HOS cells (HCR). Chromatographic profiling of BAM-SX and AIM-SO by high performance thin layer chromatography resulted in identification of berberine (Rf 0.55), palmitine (Rf 0.50) in BAM-SX and azadirachtin A (Rf 0.36), azadirachtin B (Rf 0.56), nimbin (Rf 0.80), and nimbolide (Rf 0.43) in AIM-SO. The cytotoxic sensitivity obtained can be attributed to the above compounds. Our results highlight the importance of extraction technique and subsequent mechanism of action of multi-constituential B. aristata and A. indica against both sensitive and drug refractory HOS cells

Steroid Receptor Coactivator 2 Is Critical for Progesterone-Dependent Uterine Function and Mammary Morphogenesis in the Mouse

Although the essential involvement of the progesterone receptor (PR) in female reproductive tissues is firmly established, the coregulators preferentially enlisted by PR to mediate its physiological effects have yet to be fully delineated. To further dissect the roles of members of the steroid receptor coactivator (SRC)/p160 family in PR-mediated reproductive processes in vivo, state-of-the-art cre-loxP engineering strategies were employed to generate a mouse model (PR(Cre/+) SRC-2(flox/flox)) in which SRC-2 function was abrogated only in cell lineages that express the PR. Fertility tests revealed that while ovarian activity was normal, PR(Cre/+) SRC-2(flox/flox) mouse uterine function was severely compromised. Absence of SRC-2 in PR-positive uterine cells was shown to contribute to an early block in embryo implantation, a phenotype not shared by SRC-1 or -3 knockout mice. In addition, histological and molecular analyses revealed an inability of the PR(Cre/+) SRC-2(flox/flox) mouse uterus to undergo the necessary cellular and molecular changes that precede complete P-induced decidual progression. Moreover, removal of SRC-1 in the PR(Cre/+) SRC-2(flox/flox) mouse uterus resulted in the absence of a decidual response, confirming that uterine SRC-2 and -1 cooperate in P-initiated transcriptional programs which lead to full decidualization. In the case of the mammary gland, whole-mount and histological analysis disclosed the absence of significant ductal side branching and alveologenesis in the hormone-treated PR(Cre/+) SRC-2(flox/flox) mammary gland, reinforcing an important role for SRC-2 in cellular proliferative changes that require PR. We conclude that SRC-2 is appropriated by PR in a subset of transcriptional cascades obligate for normal uterine and mammary morphogenesis and function

A Multi-wavelength Study of the Turbulent Central Engine of the Low-mass AGN Hosted by NGC 404

The nearby dwarf galaxy NGC 404 harbors a low-luminosity active galactic nucleus powered by the lowest-mass (<150,000 M ⊙) central massive black hole (MBH), with a dynamical mass constraint, currently known, thus providing a rare low-redshift analog to the MBH "seeds" that formed in the early universe. Here, we present new imaging of the nucleus of NGC 404 at 12–18 GHz with the Karl G. Jansky Very Large Array (VLA) and observations of the CO(2–1) line with the Atacama Large Millimeter/Submillimeter Array (ALMA). For the first time, we have successfully resolved the nuclear radio emission, revealing a centrally peaked, extended source spanning 17 pc. Combined with previous VLA observations, our new data place a tight constraint on the radio spectral index and indicate an optically thin synchrotron origin for the emission. The peak of the resolved radio source coincides with the dynamical center of NGC 404, the center of a rotating disk of molecular gas, and the position of a compact, hard X-ray source. We also present evidence for shocks in the NGC 404 nucleus from archival narrowband HST imaging, Chandra X-ray data, and Spitzer mid-infrared spectroscopy, and discuss possible origins for the shock excitation. Given the morphology, location, and steep spectral index of the resolved radio source, as well as constraints on nuclear star formation from the ALMA CO(2–1) data, we find the most likely scenario for the origin of the radio source in the center of NGC 404 to be a radio outflow associated with a confined jet driven by the active nucleus

Transcriptional Response of the Murine Mammary Gland to Acute Progesterone Exposure

Our mechanistic understanding of progesterone’s involvement in murine mammary morphogenesis and tumorigenesis is dependent on defining effector pathways responsible for transducing the progesterone signal into a morphogenetic response. Toward this goal, microarray methods were applied to the murine mammary gland to identify novel downstream gene targets of progesterone. Consistent with a tissue undergoing epithelial expansion, mining of the progesterone-responsive transcriptome revealed the up-regulation of functional gene classes involved in epithelial proliferation and survival. Reassuringly, signaling pathways previously reported to be responsive to progesterone were also identified. Mining this informational resource for rapidly induced genes, we identified “inhibitor of differentiation 4” (Id4) as a new molecular target acutely induced by progesterone exposure. Mammary Id4 is transiently induced during early pregnancy and colocalizes with progesterone receptor (PR) expression, suggesting that Id4 mediates the early events of PR-dependent mammary morphogenesis. Chromatin immunoprecipitation assay detecting direct recruitment of ligand occupied PR to the Id4 promoter supports this proposal. Given that Id4 is a member of the Id family of transcriptional regulators that have been linked to the maintenance of proliferative status and tumorigenesis, the establishment of a mechanistic link between PR signaling and Id4 promises to furnish a wider conceptual framework with which to advance our understanding of normal and abnormal mammary epithelial responses to progestins. In sum, the progesterone-responsive transcriptome described herein not only reinforces the importance of progesterone in mammary epithelial expansion but also represents an invaluable information resource with which to identify novel signaling paradigms for mammary PR action