Transcriptional Regulation of TCF/LEF and PPARγ by Daidzein and Genistein in 3T3-L1 Preadipocytes.

Adipogenesis is central to adipose tissue plasticity and lipid homeostasis. Regulation of adipogenic signaling by phytoestrogens has been implicated as a potential therapeutic strategy for obesity-related disease. However, it remains unclear how these compounds directly impact transcriptional control of adipogenesis. As such, the focus of this study was to determine how daidzein and genistein effect transcriptional activation of peroxisome proliferator-activated receptor gamma (PPARγ) and TCF/LEF in 3T3-L1 preadipocytes. We also measured the effect of estrogen receptor (ER) knockdown on expression of preadipocyte (i.e., Pref1) and adipocyte (i.e., Fabp4) markers in cells treated with varying concentrations of daidzein or genistein (i.e., 10-4, 10-7, and 10-10). Our findings showed that activation of TCF/LEF was induced by daidzein and genistein in undifferentiated and differentiated 3T3-L1 preadipocytes. Conversely, PPARγ reporter activity was inhibited by genistein, which corresponded with a reduction in cell diameter of differentiated preadipocytes. Daidzein increased cell diameter, as well as reduced Pref1 abundance in undifferentiated cells. Although small, there was a significant reduction in Pref1 and Fabp4 abundance in undifferentiated cells with ERα and ERß knockdown. However, reduced abundance of ER subtypes exhibited no significant effect on phytoestrogen treatment. Collectively, our findings show phytoestrogens distinctly regulate adipogenic transcription factors and thus, may have implications for adipose dysfunction and obesity-related disease.

The effect of lipid supplements on ruminal bacteria in continuous culture fermenters varies with the fatty acid composition.

A single flow continuous culture fermenter system was used in this study to investigate the influence of dietary lipid supplements varying in their fatty acid content on the DNA concentration of selected rumen bacteria. Four continuous culture fermenters were used in a 4 × 4 Latin square design with four periods of 10 d each. Treatment diets were fed at 45 g/d (DM basis) in three equal portions during the day. The diets were: 1) control (CON), 2) control with animal fat source (SAT), 3) control with soybean oil (SBO), and 4) control with fish oil (FO). Lipid supplements were added at 3% of diet DM. The concentrations of total volatile fatty acids and acetate were not affected (P>0.05) by lipid supplements. Concentrations of propionate, iso-butyrate, valerate and iso-valerate were highest (P<0.05) with the FO diet compared with the other treatment diets. The concentration of til C18:l (vaccenic acid, VA) in effluents increased (P<0.05) with SBO and FO diets and was highest with the SBO diet. The concentrations of C18:0 in effluents were lowest (P<0.05) for the FO diet compared with the other treatment diets. Concentrations of DNA for Anaerovibrio lipolytica, and Butyrivibrio proteoclasticus in fermenters were similar (P>0.05) for all diets. The DNA concentrations of Butyrivibrio fibrisolvens and Ruminococcus albus in fermenters were lowest (P<0.05) with the FO diet but were similar (P>0.05) among the other treatment diets. Selenomonas ruminantium DNA concentration in fermenters was highest (P<0.05) with the FO diet. In conclusion, SBO had no effect on bacterial DNA concentrations tested in this study and the VA accumulation in the rumen observed on the FO diet may be due in part to FO influence on B. fibrisolvens, R. albus, and S. ruminantium.

Natural selection and functional genetic variation in the p53 pathway.

The allele frequencies of two functional single-nucleotide polymorphisms (SNPs) in the p53 pathway, the MDM2 SNP309 and TP53 Arg72Pro, vary dramatically among populations. That the frequencies of the TP53 SNP follow a clinal distribution may suggest that selective pressure from environmental variables correlated with latitude contributed to these observed population differences. Recently, winter temperature and UV radiation were found to be significantly correlated with the TP53 and the MDM2 SNPs, respectively, in East Asians; whether these correlations are more extreme than expected based upon nonselective factors such as patterns of human migration remains unclear. Here, we genotyped these two SNPs in 971 unrelated individuals from 52 unique populations worldwide and tested for correlations with both latitude and a number of climate-related environmental variables on a global scale, controlling for these neutral processes. The TP53 SNP was associated with a significant selection signal for a few climate variables, such as short-wave radiation flux in the winter, but these signals were no longer significant after correction for multiple tests. The MDM2 SNP did not exhibit a significant signal with any climate variable. Therefore, these SNPs are unlikely to be under selective pressure driven by these variables. Thus, these data underscore the need to incorporate population history when assessing signatures of selection.

Genome-wide association study to identify novel loci associated with therapy-related myeloid leukemia susceptibility.

Therapy-related acute myeloid leukemia (t-AML) is a rare but fatal complication of cytotoxic therapy. Whereas sporadic cancer results from interactions between complex exposures and low-penetrance alleles, t-AML results from an acute exposure to a limited number of potent genotoxins. Consequently, we hypothesized that the effect sizes of variants associated with t-AML would be greater than in sporadic cancer, and, therefore, that these variants could be detected even in a modest-sized cohort. To test this, we undertook an association study in 80 cases and 150 controls using Affymetrix Mapping 10K arrays. Even at nominal significance thresholds, we found a significant excess of associations over chance; for example, although 6 associations were expected at P less than .001, we found 15 (P(enrich) = .002). To replicate our findings, we genotyped the 10 most significantly associated single nucleotide polymorphisms (SNPs) in an independent t-AML cohort (n = 70) and obtained evidence of association with t-AML for 3 SNPs in the subset of patients with loss of chromosomes 5 or 7 or both, acquired abnormalities associated with prior exposure to alkylator chemotherapy. Thus, we conclude that the effect of genetic factors contributing to cancer risk is potentiated and more readily discernable in t-AML compared with sporadic cancer.