In the yeast Saccharomyces cerevisiae, fermentation is the major pathway for energy production, even under aerobic conditions. However, when glucose becomes scarce, ethanol produced during fermentation is used as a carbon source, requiring a shift to respiration. This adaptation results in massive reprogramming of gene expression. Increased expression of genes for gluconeogenesis and the glyoxylate cycle is observed upon a shift to ethanol and, conversely, expression of some fermentation genes is reduced. The zinc cluster proteins Cat8, Sip4, and Rds2, as well as Adr1, have been shown to mediate this reprogramming of gene expression. In this study, we have characterized the gene YBR239C encoding a putative zinc cluster protein and it was named ERT1 (ethanol regulated transcription factor 1). ChIP-chip analysis showed that Ert1 binds to a limited number of targets in the presence of glucose. The strongest enrichment was observed at the promoter of PCK1 encoding an important gluconeogenic enzyme. With ethanol as the carbon source, enrichment was observed with many additional genes involved in gluconeogenesis and mitochondrial function. Use of lacZ reporters and quantitative RT-PCR analyses demonstrated that Ert1 regulates expression of its target genes in a manner that is highly redundant with other regulators of gluconeogenesis. Interestingly, in the presence of ethanol, Ert1 is a repressor of PDC1 encoding an important enzyme for fermentation. We also show that Ert1 binds directly to the PCK1 and PDC1 promoters. In summary, Ert1 is a novel factor involved in the regulation of gluconeogenesis as well as a key fermentation gene. IN the yeast Saccharomyces cerevisiae, glucose is the preferred carbon source and fermentation is the major pathway for energy production, even under aerobic conditions. However, when glucose becomes scarce, ethanol produced during fermentation is used as a carbon source, a process requiring a shift to a respiration mode. Other nonfermentable carbon sources, such as lactate, acetate, or glycerol, can also be used by yeast . The shift from fermentative to nonfermentative metabolism results in massive reprogramming of gene expression for the use of ethanol (Derisi et al. 1997;Roberts and Hudson 2006). For example, increased expression of genes for gluconeogenesis and the glyoxylate cycle is observed upon a shift to ethanol and, conversely, expression of some fermentation genes is reduced under these conditions. An important player in the regulation of this process is the Snf1 kinase (Hedbacker and Carlson 2008;Zaman et al. 2008;Zhang et al. 2010;Broach 2012). Snf1 becomes activated under low glucose conditions resulting in the phosphorylation of a number of substrates that include DNA binding proteins such as Mig1, Cat8, Sip4, and Rds2 (for reviews see Schüller 2003;Turcotte et al. 2011).Mig1 and Adr1 belong to the family of zinc finger proteins of the Cys 2 His 2 type. Mig1 is a transcriptional repressor that, following phosphorylation by Snf1, undergoes nucleocytoplasmic shuffling...

Polybrominated diphenyl ether(s) (PBDE) are ubiquitous environmental contaminants that bind and cross the placenta but their effects on pregnancy outcome are unclear. It is possible that environmental contaminants increase the risk of inflammation-mediated pregnancy complications such as preterm birth by promoting a proinflammatory environment at the maternal-fetal interface. We hypothesized that PBDE would reduce IL-10 production and enhance the production of proinflammatory cytokines associated with preterm labor/birth by placental explants. Second trimester placental explants were cultured in either vehicle (control) or 2 μM PBDE mixture of congers 47, 99 and 100 for 72 h. Cultures were then stimulated with 106 CFU/ml heat-killed Escherichia coli for a final 24 h incubation and conditioned medium was harvested for quantification of cytokines and PGE2. COX-2 content and viability of the treated tissues were then quantified by tissue ELISA and MTT reduction activity, respectively. PBDE pre-treatment reduced E. coli-stimulated IL-10 production and significantly increased E. coli-stimulated IL-1β secretion. PBDE exposure also increased basal and bacteria-stimulated COX-2 expression. Basal, but not bacteria-stimulated PGE2, was also enhanced by PBDE exposure. No effect of PBDE on viability of the explants cultures was detected. In summary, pre-exposure of placental explants to congers 47, 99, and 100 enhanced the placental proinflammatory response to infection. This may increase the risk of infection-mediated preterm birth by lowering the threshold for bacteria to stimulate a proinflammatory response(s).

Preterm birth is a leading cause of perinatal morbidity and mortality that is often associated with ascending infections from the lower genital tract. Recent studies with animal models have suggested that developmental exposure to the environmental toxin 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) can increase the risk of preterm birth in the offspring. How TCDD may modify placental immunity to ascending infections is unclear. Therefore, we studied the effects of TCDD treatment on basal and Escherichia coli-stimulated cytokine production by placental explants. Cultures of second-trimester placentas were treated with up to 40 nM TCDD for 72 h and then stimulated with 107 CFU/ml E. coli for an additional 24 h. Concentrations of cytokines and PGE2 were measured in conditioned medium by immunoassay. TCDD exposure increased mRNA levels of IL-1β by unstimulated cultures, but no effects on protein levels of this cytokine were detected. TNF-α production was unaffected by TCDD for unstimulated cultures, but pre-treatment with 40 nM TCDD significantly increased E. coli-stimulated TNF-α production. Both basal and bacteria-stimulated PGE2 and COX-2 gene expression were enhanced by TCDD pretreatment. In contrast, production of the anti-inflammatory cytokine, IL-10, was reduced by TCDD pretreatment for both unstimulated and E. coli-stimulated cultures. No effect of TCDD on the viability of the cultures was detected. These results suggest that TCDD exposure may shift immunity to enhance a proinflammatory phenotype at the maternal–fetal interface that could increase the risk of infection-mediated preterm birth.

Problem Placental infection induces increased levels of pro‐inflammatory cytokines, which have been implicated in the pathogenesis of pre‐term labor. Endotoxin tolerance is a phenomenon in which exposure to a dose of endotoxin makes tissue less responsive to subsequent exposures. The objective of our study was to determine whether repeated exposure to endotoxin will induce a tolerant phenotype in normal human second‐trimester placental tissue. Methods of study Human second‐trimester placental explants from elective termination of pregnancy were cultured and exposed to endotoxin (LPS). After 24 hours, the media was collected for analysis, and the explants were re‐exposed to LPS after adding fresh media for another 24 hours. This process was repeated for a total of 4 LPS doses. The media was collected from each day and analyzed for cytokine levels. Results The first LPS treatment stimulated the secretion of the pro‐inflammatory cytokines IL‐1β and TNF‐α. However, their production was significantly diminished with repeated LPS doses. Production of the anti‐inflammatory cytokines, IL‐1ra and IL‐10, was also stimulated by the first LPS treatment, but secretion was more gradually and moderately decreased with repeated LPS doses compared to the pro‐inflammatory cytokines. The ratios of the anti‐inflammatory/pro‐inflammatory mediators (IL‐1ra/IL‐1β and IL‐10/TNF‐α) indicate a progressively more anti‐inflammatory milieu with repeated LPS doses. Conclusion Repeated LPS exposure of human second‐trimester placental tissues induced endotoxin tolerance. We speculate that endotoxin tolerance at the maternal‐fetal interface will protect the fetus from exaggerated inflammatory responses after repeated infectious exposure.