BACKGROUNDInflammation plays a pivotal role in cardiac remodeling, especially in myocardial fibrosis. Abnormal growth of cardiac fibroblasts is critically involved in the pathophysiology of cardiac hypertrophy/remodeling. Previous study has demonstrated that many inflammation stimulating factors trigger transforming growth factor-β (TGF-β) induction and reactive myocardial fibrosis. Activin A (ACT A) is a member of TGF-β superfamily, and follistatin (FS) is an activin-binding protein, i.e. an antagonist of ACT A. Our previous studies have shown that ACT A-FS imbalance occurs in rats with heart failure (HF), and overexpression of ACT A can lead to ventricular remodeling, and resultant HF. Low expression of FS after myocardial infarction further exacerbated HF. The pathogenic change resulting from overexpression of ACT A is consistent with that of overexpression of angiotensin II (AngII). Ventricular remodeling includes cardiocyte remodeling and myocardial interstitial collagen deposition and fibrosis. Therefore, the present study was designed to investigate the effects of inflammatory factors on the ACT A-FS and the secretions of cardiac fibroblasts in order to explore in depth the mechanism of myocardial fibrosis.

METHODSA rat model with HF was established, and the results showed that there was a greater degree of cardiac fibrosis in HF rats. In addition, we found that there was an imbalance of the ACT A/FS system in HF rats, which was characterized by increased levels of ACT A. Further, primary rat cardiac fibroblasts were cultured and the MTT assay was performed to determine the effect of the inflammatory factor-bacterial endotoxin lipopolysaccharide (LPS) on cardiac fibroblast proliferation.

RESULTSThe results showed that LPS can stimulate the cardiac fibroblasts to proliferate in a dose-dependent manner. Cellular immunohistochemical staining showed that the rat cardiac fibroblasts themselves could express ACT A and FS proteins, and stimulation by LPS could apparently promote the cultured primary rat cardiac fibroblasts to secrete ACT A, but inhibit the secretion of FS. The results also showed that ACT A promoted, in a dose-dependent manner, the proliferation of the cultured primary rat cardiac fibroblasts, and the expression of collagen types I and III. Moreover, ACT A promoted, in a dose dependent manner, the cardiac fibroblasts to secrete nitric oxide (NO), and unregulated the expression of inducible nitric oxide synthase (iNOS) mRNA.

CONCLUSIONSThese results suggest that the inflammatory mediator LPS can promote ACT A-FS imbalance in cardiac fibroblasts, mainly overexpression of ACT A. Overexpression of ACT A promotes the proliferation and the secretion of collagens in cardiac fibroblasts through autocrine/paracrine stimulation of NO, and is involved in the pathological process of myocardial fibrosis.

Activins ; genetics ; metabolism ; Animals ; Cell Proliferation ; Cells, Cultured ; Enzyme-Linked Immunosorbent Assay ; Female ; Fibroblasts ; cytology ; drug effects ; Follistatin ; genetics ; metabolism ; Immunohistochemistry ; Lipopolysaccharides ; pharmacology ; Myocardium ; cytology ; Nitric Oxide ; metabolism ; Rats ; Rats, Wistar ; Real-Time Polymerase Chain Reaction ; Ventricular Remodeling ; drug effects

Previously, we found that high doses of genistein show an inhibitory effect on uterine leiomyoma (UtLM) cell proliferation. In this study, using microarray analysis and Ingenuity Pathways Analysis(TM), we identified genes (up- or down-regulated, > or = 1.5 fold, P < or = 0.001), functions and signaling pathways that were altered following treatment with an inhibitory concentration of genistein (50 microg/ml) in UtLM cells. Downregulation of TGF-beta signaling pathway genes, activin A, activin B, Smad3, TGF-beta2 and genes related to cell cycle regulation, with the exception of the upregulation of the CDK inhibitor P15, were identified and validated by real-time RT-PCR studies. Western blot analysis further demonstrated decreased protein expression of activin A and Smad3 in genistein-treated UtLM cells. Moreover, we found that activin A stimulated the growth of UtLM cells, and the inhibitory effect of genistein was partially abrogated in the presence of activin A. Overexpression of activin A and Smad3 were found in tissue samples of leiomyoma compared to matched myometrium, supporting the contribution of activin A and Smad3 in promoting the growth of UtLM cells. Taken together, these results suggest that down-regulation of activin A and Smad3, both members of the TGF-beta pathway, may offer a mechanistic explanation for the inhibitory effect of a high-dose of genistein on UtLM cells, and might be potential therapeutic targets for treatment of clinical cases of uterine leiomyomas.
Activins/*genetics/metabolism/pharmacology ; Anticarcinogenic Agents/*pharmacology ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Cyclin-Dependent Kinase Inhibitor p15/genetics/metabolism ; Down-Regulation ; Female ; Genistein/*pharmacology ; Humans ; Leiomyoma/*metabolism ; Oligonucleotide Array Sequence Analysis ; Signal Transduction/drug effects ; Smad3 Protein/*genetics/metabolism ; Transforming Growth Factor beta/*genetics/metabolism ; Up-Regulation ; Uterine Neoplasms/*metabolism

OBJECTIVETo investigate the roles of mouse erythroid differentiation and denucleation factor (MEDDF), a novel factor cloned in our laboratory recently, in erythroid terminal differentiation.

METHODSMouse erythroleukemia (MEL) cells were transfected with eukaryotic expression plasmid pcDNA-MEDDF. Then we investigated the changes on characteristics of cell growth by analyzing cells growth rate, mitotic index and colony-forming rate in semi-solid medium. The expressions of c-myc and beta-globin genes were analysed by semi-quantitative RT-PCR.

RESULTSMEL cells transfected with pcDNA-MEDDF showed significant lower growth rate, mitotic index, and colony-forming rate in semi-solid medium (P<0.01). The percentage of benzidine-positive cells was 32.8% after transfection. The expression of beta-globin in cells transfected with pcDNA-MEDDF was 3.43 times higher than that of control (MEL transfected with blank vector, pcDNA3.1), and the expression of c-myc decreased by 66.3%.

CONCLUSIONSMEDDF can induce differentiation of MEL cell and suppress its malignancy.

Activins ; genetics ; pharmacology ; Animals ; Cell Differentiation ; drug effects ; Cell Division ; drug effects ; Friend murine leukemia virus ; Globins ; biosynthesis ; genetics ; Inhibin-beta Subunits ; genetics ; pharmacology ; Leukemia, Erythroblastic, Acute ; metabolism ; pathology ; Mice ; Proto-Oncogene Proteins c-myc ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; Transfection ; Tumor Cells, Cultured

The heterodimeric c-Jun/c-Fos, an activator protein-1 (AP-1) has been implicated in mesoderm induction (Dong et al., 1996; Kim et al., 1998) whereas the homodimer of c-Jun was reported to be involved in neural inhibition during the early development of Xenopus embryos. During the early vertebrate development AP-1 involvement in the neural induction is still not clearly understood. We report here that AP-1 has a role in Zic3 expression, a critical proneural gene and a primary regulator of neural and neural crest development (Nakata et al., 1997; Nakata et al., 1998). AP-1 was able to induce the Zic3 gene in a dose dependent manner but other homo- or hetero-dimeric proteins, such as c-Jun/c-Jun, JunD/FosB or JunD/Fra-1 were not. The inhibition of AP-1 activity using morpholino antisenses of c-jun mRNAs blocked the Zic3 expression induced by activin. In addition, co-injection of c-jun mRNA rescued the down-regulated Zic3 expression. The promoter region of isolated Zic3 genomic DNA was found to possess several consensus-binding site of AP-1. Thus, in the functional assays, AP-1 could increase promoter activity of Zic3 gene. These findings suggest that proneural gene, Zic3 may be regulated by heterodimeric AP-1(c-Jun/c-Fos) and it may have a role in activin signaling for the regulation of neural specific gene, Zic3.
Activins/pharmacology/physiology ; Animals ; Base Sequence ; Binding Sites/genetics ; Consensus Sequence/genetics ; Dimerization ; Embryo, Nonmammalian/metabolism ; *Gene Expression Regulation, Developmental ; Homeodomain Proteins/*genetics ; Molecular Sequence Data ; Promoter Regions (Genetics)/genetics ; Proto-Oncogene Proteins c-fos/genetics/physiology ; Proto-Oncogene Proteins c-jun/genetics/physiology ; RNA, Antisense/genetics ; Research Support, Non-U.S. Gov't ; Transcription Factor AP-1/genetics/*physiology ; Transcription Factors/*genetics ; *Transcription, Genetic ; Up-Regulation ; Xenopus Proteins/*genetics ; Xenopus laevis/*embryology/*genetics