IRF-4,8 are two specialized members of the interferon regulatory factor (IRF) family that have been implicated in regulating immunoglobulin (Ig) light-chain gene transcription during B-lymphocyte development (Pongubala et al. 1992;Eisenbeis et al. 1995;Shaffer et al. 1997;Brass et al. 1999; Muljo and Schlissel 2002). They are more highly related to one another than to other IRFs and are selectively expressed in the lymphoid and myeloid lineages of the immune system (for review, see Taniguchi et al. 2001). IRF-4,8 bind very weakly to DNA-containing IRF sites, but are recruited to their binding sites via interactions with other transcription factors. In particular, the related Ets family transcription factors PU.1 and Spi-B have been shown to recruit IRF-4 or IRF-8 to Ets-IRF composite elements (EICE) in Ig 3Ј and enhancers (Pongubala et al. 1992;Eisenbeis et al. 1995;Brass et al. 1999;Escalante et al. 2002). These heterodimeric protein complexes have been implicated in the control of Ig light-chain gene transcription. PU.1 is required for early B-cell development and Spi-B is important for B-cell activation (Scott et al. 1994;Su et al. 1997). It remains to be determined whether PU.1/Spi-B regulate Ig light-chain gene expression during the pre-B-to-B transition. IRF-4 −/− mutant mice exhibit profound defects in B-and T-cell activation that are manifested in the failure to mount antibody, cytotoxic, or antitumor responses (Mittrucker et al. 1997;Rengarajan et al. 2002). IRF-8 −/− mutant mice are impaired in macrophage development, highly susceptible to viral infections, and manifest a chronic myelogenous leukemia-like syndrome (Holtschke et al. 1996). Loss of either IRF-4 or IRF-8 does not block the generation of B lymphocytes. Given their structural relatedness and similar molecular properties, we sought to examine whether they function redundantly to regulate Ig lightchain gene expression and the pre-B-to-B transition. (Fig. 1A). Strikingly, the double mutant mice lacked sIgM + peripheral B lymphocytes (Fig. 1B). In contrast, splenic T lymphocytes, (CD4 + or CD8 + ) were present in the double mutant mice, albeit with reduced numbers (Fig. 1C). We note that loss of IRF-4 and IRF-8 does not impair T-cell development in the thymus (data not shown). We next examined B-cell generation in the bone marrow. Immature IgM + B cells were absent in the IRF-4,8 −/− bone marrow (Fig. 1D). These results establish that the combined loss of IRF-4,8 causes a lineage-specific block to B-cell development. It should be noted that as is the case for IRF-8 −/− mice, there was an increase in the numbers of myeloid cells Fig. 2A). The levels of HSA expression on the mutant B220 + , CD43 + , BP-1 + , B-lineage cells were particularly high, suggesting that they represent transitional pre-B cells, which are a subset of fraction C cells in the nomenclature of Hardy et al. (1991). The disproportionate increase in the percentage fraction C cells in the IRF-4,8 −/− bone marrow ( Fig. 2A) was also reflected in a substantial increase in their a...

Resveratrol is a natural phytoalexin compound found in grapes and other food products. In this study, the effect of resveratrol on the growth of human breast cancer cells was examined. Results show that resveratrol inhibits the growth of estrogen receptor(ER)-positive MCF-7 cells in a dose-dependent fashion. Detailed studies with MCF-7 cells demonstrate that resveratrol antagonized the growth-promoting effect of 17-beta-estradiol (E2) in a dose-dependent fashion at both the cellular (cell growth) and the molecular (gene activation) levels. At 5 x 10(-6) M, resveratrol abolished the growth-stimulatory effect mediated by concentrations of E2 up to 10(-9) M. The antiestrogenic effect of resveratrol could be observed at a concentration of 10(-6) M and above. The antiestrogenic effect of resveratrol was also demonstrated at the molecular level. Resveratrol in a dose-dependent fashion antagonized the stimulation by E2 of progesterone receptor gene expression in MCF-7 cells. Moreover, expression of transforming growth factor-alpha and insulin-like growth factor I receptor mRNA was inhibited while the expression of transforming growth factor beta2 mRNA was significantly elevated in MCF-7 cells cultivated in the presence of resveratrol (10(-5) M). In summary, our results show that resveratrol, a partial ER agonist itself, acts as an ER antagonist in the presence of estrogen leading to inhibition of human breast cancer cells.

The molecular mechanism by which virus induces expression of the early inflammatory genes has not yet been completely elucidated. Previous studies indicated that the virus-mediated transcription of type I interferon (IFN) genes required activation of two members of IFN regulatory factor (IRF) family, IRF-3 and IRF-7, where the expression of IRF-7 was found to be indispensable for the induction of IFNA genes. To determine the factors that regulate expression of IRF-7 gene, as well as its inducibility by type I IFNs, we have isolated and characterized the promoter and first intron of the human IRF-7 gene. This region shows a presence of two potential interferon-sensitive response elements (ISRE/ IRF-E). However, only the ISRE present in the first intron was functional and conferred interferon inducibility in a transient transfection assay. Using a pull-down assay with an oligodeoxynucleotide corresponding to this ISRE immobilized to magnetic beads, we have demonstrated that this ISRE binds ISGF3 complex and IRF-1 from the extract of IFN-treated cells but not from the untreated cells. We have further shown that the previously observed lack of expression of IRF-7 in 2fTGH fibrosarcoma cell line, correlated with hypermethylation of the CpG island in the human IRF-7 promoter. The repression of the promoter activity was relieved by treatment with DNA methyltransferase inhibitor 5-azadeoxycytidine. In vitro methylation of IRF-7 promoter silenced IRF-7 directed expression of luciferase gene in HeLa cells that express endogenous IRF-7 gene. Whether silencing of IRF-7 by methylation is instrumental for the process of tumorigenesis remains to be determined.Expression of eukaryotic genes is regulated at multiple levels including the accessibility of promoter DNA for binding of basic transcriptional machinery or the specific transcription factors and chromatin structure around the potential promoters. The molecular mechanism by which virus activates expression of the early inflammatory genes has not yet been completely elucidated. It was shown, however, that activation of the NFB family of transcription factors in infected cells plays a critical role in the transcriptional activation of many cytokine and chemokine genes, since large number of these genes contains NFB-binding sites in their promoters. Recently the importance of another family of transcription factors as the mediators of virus induced signaling has emerged. These factors designated interferon (IFN)

PC-cell derived growth factor (PCDGF) is an 88-kDa growth factor originally purified from the highly tumorigenic teratoma PC cell line and corresponds to the epithelin͞granulin precursor. In teratoma cells, PCDGF expression was shown to be essential for tumorigenicity. We have reported that PCDGF was expressed in estrogen receptorpositive (ER ؉ ) human mammary epithelial cells in an estrogen-dependent fashion. In this study,

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