Estrogen is a growth factor that stimulates cell proliferation. The effects of estrogen are mediated through the estrogen receptors, ER␣ and ER␤, which function as ligand-induced transcription factors and belong to the nuclear receptor superfamily. On the other hand, TGF-␤ acts as a cell growth inhibitor, and its signaling is transduced by Smads. Although a number of studies have been made on the cross-talk between estrogen/ER␣ and TGF-␤/Smad signaling, whose molecular mechanisms remain to be determined. Here, we show that ER␣ inhibits TGF-␤ signaling by decreasing Smad protein levels. ER␣-mediated reductions in Smad levels did not require the DNA binding ability of ER␣, implying that ER␣ opposes the effects of TGF-␤ via a novel non-genomic mechanism. Our analysis revealed that ER␣ formed a protein complex with Smad and the ubiquitin ligase Smurf, and enhanced Smad ubiquitination and subsequent degradation in an estrogen-dependent manner. Our observations provide new insight into the molecular mechanisms governing the non-genomic functions of ER␣.

Resistance rates for both clarithromycin and metronidazole appear to reflect the annual consumption of these agents. The high rate of clarithromycin resistance in Japan suggests that the effectiveness of clarithromycin-based therapies may be compromised in the near future.

In order to develop a new method for determination of the G+C content of a DNA, preparations from 26 bacterial strains and salmon sperm were digested to form 5'-deoxyribonucleotide-monophosphates (dNMP) with nuclease PI and subjected to high performance liquid chromatography (HPLC). Chromatograms indicated excellent separation of the components, and the data analysis suggested sufficient reproducibility and reasonable A/T and G/C ratios over a wide range (39 to 72mol%) of G+C values.

BackgroundLiver fibrosis is caused by chemicals or viral infection. The progression of liver fibrosis results in hepatocellular carcinogenesis in later stages. Recent studies have revealed the importance of DNA hypermethylation in the progression of liver fibrosis to hepatocellular carcinoma (HCC). However, the importance of DNA methylation in the early-stage liver fibrosis remains unclear.MethodsTo address this issue, we used a pathological mouse model of early-stage liver fibrosis that was induced by treatment with carbon tetrachloride (CCl4) for 2 weeks and performed a genome-wide analysis of DNA methylation status. This global analysis of DNA methylation was performed using a combination of methyl-binding protein (MBP)-based high throughput sequencing (MBP-seq) and bioinformatic tools, IPA and Oncomine. To confirm functional aspect of MBP-seq data, we complementary used biochemical methods, such as bisulfite modification and in-vitro-methylation assays.ResultsThe genome-wide analysis revealed that DNA methylation status was reduced throughout the genome because of CCl4 treatment in the early-stage liver fibrosis. Bioinformatic and biochemical analyses revealed that a gene associated with fibrosis, secreted phosphoprotein 1 (Spp1), which induces inflammation, was hypomethylated and its expression was up-regulated. These results suggest that DNA hypomethylation of the genes responsible for fibrosis may precede the onset of liver fibrosis. Moreover, Spp1 is also known to enhance tumor development. Using the web-based database, we revealed that Spp1 expression is increased in HCC.ConclusionsOur study suggests that hypomethylation is crucial for the onset of and in the progression of liver fibrosis to HCC. The elucidation of this change in methylation status from the onset of fibrosis and subsequent progression to HCC may lead to a new clinical diagnosis.

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