Effect of estrogen and inhibition of phosphatidylinositol-3 kinase on Akt and FOXO1 in rat uterus.
ABSTRACT The importance of FOXO transcription factors in regulating different aspects of cellular homeostasis and apoptosis has become apparent. Akt/protein kinase B has been shown to phosphorylate and inactivate members of FOXO family of transcription factors. Akt and its upstream regulator, phosphatidylinositol-3 kinase (PI3K) are involved in rapid action of estrogen (E2) in different cells and tissues. The aim of the present study was to analyze the E2/PI3K/Akt/FOXO pathway in rat uterus. In response to E2, phosphorylation of Akt/PKB on Ser473 and FOXO1 on Ser256 and Thr24 residues increased but with distinct kinetics, regulating the activation and inactivation of Akt and FOXO1 proteins, respectively. The antiestrogen ICI 182,780 prevented E2 induced Akt activation suggesting that estrogen receptors mediate this effect of E2. Intrauterine injection of Wortmannin caused a decrease in the phosphorylation of Ser473 of Akt, and attenuated phosphorylation of its downstream target FOXO1 at Ser256 and at Thr24. However, the effect of E2 on phosphorylation of Thr24 showed a kinetic pattern distinct from that of Ser256. Our results suggest that the E2/PI3K/Akt/FOXO1 pathway in rat uterus is functioning even at the lack of ovarian hormones and responses to E2 treatment. Estradiol increases Akt phosphorylation through a Wortmannin sensitive way, presumably involving PI3K. The present work shows that PI3K plays a crucial role in the phosphorylation and inactivation of FOXO1 in vivo, indicating that the regulation of this transcription factor is a more complex event in uterine cells requiring further investigations.
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ABSTRACT: Administration of N-carbamylglutamate (NCG), an analogue of endogenous N-acetyl-glutamate (an activator of arginine synthesis) has been shown to enhance neonatal growth by increasing circulating arginine levels. However, the effect of NCG on pregnancy remains unknown. This study examined the effects of NCG on pregnancy outcome and evaluated potential mechanisms involved. Reproductive performance, embryo implantation, and concentration of amino acids in serum and uterine flushing, were determined in rats fed control or NCG supplemented diets. Ishikawa cells and JAR cells were used to examine the mechanism by which NCG affects embryo implantation. Dietary NCG supplementation increased serum levels of arginine, onithine, and proline, as well as uterine levels of arginine, glutamine, glutamate, and proline. Additionally, it stimulated LIF expression, and enhanced the activation of signal transduction and activator of transcription 3 (Stat3), protein kinase B (PKB), and 70-kDa ribosomal protein S6 kinase (S6K1) during the periimplantation period, resulting in an increase in litter size but not birth weight. In uterine Ishikawa cells, LIF expression was also enhanced by treatment with arginine and its metabolites. In trophoblast JAR cells, treatment with arginine and its metabolites enhanced Stat3, PKB, and S6K1 activation and facilitated cellular adhesion activity. These effects were abolished by pretreatment with inhibitors of phosphatidylinositol 3-kinase (wortmannin) and mammalian target of rapamycin (rapamycin). The results demonstrate that NCG supplementation enhances pregnancy outcome and have important implications for the pregnancy outcome of mammalian species.PLoS ONE 01/2012; 7(7):e41192. · 3.73 Impact Factor
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ABSTRACT: Sirtuins, which are class III NAD-dependent histone deacetylases that regulate a number of physiological processes, play important roles in the regulation of metabolism, aging, oncogenesis, and cancer progression. Recently, a role for the sirtuins in the regulation of steroid hormone receptor signaling is emerging. In this mini-review, we will summarize current research into the regulation of estrogen, androgen, progesterone, mineralocorticoid, and glucocorticoid signaling by sirtuins in cancer. Sirtuins can regulate steroid hormone signaling through a variety of molecular mechanisms, including acting as co-regulatory transcription factors, deacetylating histones in the promoters of genes with nuclear receptor-binding sites, directly deacetylating steroid hormone nuclear receptors, and regulating pathways that modify steroid hormone receptors through phosphorylation. Furthermore, disruption of sirtuin activity may be an important step in the development of steroid hormone-refractory cancers.Journal of Endocrinology 12/2011; 213(1):37-48. · 4.06 Impact Factor
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ABSTRACT: The purpose of this study was to detect the serum microRNAs (miRNAs) that are differentially expressed in cervical squamous cell carcinoma (SCC) patients and negative controls, with a focus on the miRNA profiles of the patients before and after surgery. The aim of the study is to evaluate the potential of these miRNAs as novel markers for the post-therapeutic monitoring of cervical SCC patients. A total of 765 serum miRNAs from 10 cervical SCC patients before surgery, 10 SCC patients after surgery, and 10 negative controls were profiled using a TaqMan MicroRNA Array. A set of selected differentially expressed miRNAs were further analyzed in the patients at different perioperative periods, including preoperative, 1 week postoperative, and one month postoperative. The results showed that several serum miRNAs were differentially expressed in the cervical SCC patients compared with the negative controls, including miR-646, miR-141* and miR-542-3p. More importantly, we found that levels of specific serum miRNAs were deregulated in the pre- and postoperative stages, and these miRNAs could be useful for post-therapeutic monitoring of disease progression. Finally, we depicted a regulatory network of differentially expressed serum miRNAs, and many possible target genes were predicted in the estrogen-mediated signal pathways, supporting the hypothesis that cervical SCC is a hormone-associated gynecological disease. Our study demonstrated that the circulating miRNAs miR-646, miR-141* and miR-542-3p could potentially serve as non-invasive biomarkers for cervical SCC. The levels of these specific miRNAs might be useful for the post-therapeutic monitoring of disease progression. This is the first report showing that circulating miRNAs could serve as biomarkers for the therapeutic intervention of cervical SCC.Journal of Hematology & Oncology 01/2014; 7(1):6. · 4.46 Impact Factor