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Gene expression-based comparison of PQQ and known transcriptional regulators

ABSTRACT: Pyrroloquinoline quinone (PQQ) is a naturally occurring compound and known to improve growth and reproductive performance when added to diets of PQQ-deprived rodents. To understand its mechanism action, changes in hepatic gene expression were measured in rats fed diets with or without added PQQ. Gene expression changes for PQQ supplemented (EC50 ~ 3 nmol PQQ/Kg diet) or deficient rats were assayed by expression microarray analysis and compared to those for known transcriptional regulators (epicatechin; Epi; dexamethasone, Dex; clofibrate, Clo; phenobarbital, Pb). Two principal expression clusters were observed; one for Dex and another for Pb, Epi, Clo, and PQQ. Within the latter, a PQQ subcluster containing a unique group of genes for cell signaling and transport functions. Next, short and long term PQQ depletion and repletion protocols (48 or 36 h, respectively) were performed, leading to changes in hepatic gene expression for both time periods. Of the ~10,000 genes and ESTs analyzed, 4.7% of the transcripts were sensitive to changes in PQQ dietary status. PQQ deprivation generally caused down regulation of genes associated with mitochondriogenesis, cell differentiation, and immune function. These gene expression changes provide the basis for most of the previously published functional observations associated with PQQ deficiency and PQQ administered in pharmacological amounts. To assess PQQ’s potential functions, we used gene expression profiling through microarray technology as part of a comprehensive approach to identify potential pathways and mechanisms. Given that the systemic effects of PQQ deprivation are influenced at levels of dietary intake in the micromolar range, highly purified diets were used to reduce expression from other bioactive factors and xenobiotics, such as those found in typical rodent chow diets. To establish if the changes in gene expression in response to PQQ exposure will follow a similar pattern as other xenobiotics, the responses to PQQ exposure were contrasted with those from exposure to epicatechin (Epi), dexamethasone (Dex), clofibrate (Clo), or phenobarbital (Pb). Dietary conditions were also chosen to clarify the response to short- and longer-term PQQ deprivation. A goal was to determine if specific changes in dietary protocol or patterns could be used to identify genes important to the function of PQQ. Because it has been observed that mitochondrial-related functions are influenced by PQQ, we hypothesized that changes in genes important to fatty acid and amino acid metabolism and mitochondrial function would be likewise affected by dietary levels of PQQ. The overall study was carried out using two experiments. In this specific experiment, the gene expression profiles of Sprague Dawley (SD) rats treated with different xenobiotics were compared to the gene expression profile of PQQ treated SD rats.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE16240 | GEO | 2009/08/01

SECONDARY ACCESSION(S): PRJNA115125

REPOSITORIES: GEO

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Project description:Background: This study examines the impact of dietary fatty acids on regulation of gene expression in the mammary epithelial cells before and during puberty. Methods: The diets primarily consisted of n-9 monounsaturated fatty acids (olive oil), n-6 polyunsaturated fatty acids (safflower), saturated acids (butter), and the reference AIN-93G diet (soy oil). The dietary regimen mimics the repetitive nature of fatty acid exposure in Western diets. Dietary-induced changes in gene expression were examined in the LCM (Laser Capture Microdissected) captured mammary ductal epithelial cells at day of weaning (21 days) and at the end of puberty (50 days after birth). PCNA immunohistochemistry analysis was used to compare proliferation rates between diets. Results: Genes differentially expressed between each of the test diets and the reference diet in both age groups were significantly enriched by cell cycle genes. Some of these genes were involved in the activation of the cell cycle pathway or the G2/M check point pathway. Although there were some differences in the level of differential expression, all diets showed qualitatively same pattern of differential expression compared to the reference diet. Cluster analysis identified an expanded set of cell cycle as well as immunity and sterol metabolism related clusters of differentially expressed genes. Conclusion: Fatty acid-enriched diets significantly up-regulated proliferation above the normal physiological level at day 50. The higher cellular proliferation during puberty caused by enriched fatty acid diets pose a potential increase risk of mammary cancer in later life. The human homologs of 27 of 62 cell cycle cluster of rat genes are included in a human breast cancer cluster of 45 cell cycle related genes further emphasizing the importance of our findings in the rat model. Female, virgin Spraque-Dawley rats were obtained from Taconic Farms (Germantown, NY) at approximately 7 weeks of age and placed on one of 9 pelleted purified diets for one month. After one month of diet exposure, female rats were bred with male Sprague-Dawley rats of approximately 3 months of age. Litters were weighed and monitored throughout gestational period. Pups had access to dam’s milk as well as tap water and food throughout gestation. Pups were weaned at DOL 21 and individually housed with tap water and diets ad libitum. Rats were killed by CO2 asphyxiation and decapitated at the following two ages, DOW (DOL21) and DOL 50 with no other treatments.

Project description:High-protein diets are known to reduce adiposity in the context of high carbohydrate and Western diets. However, few studies have investigated the specific high-protein effect on lipogenesis induced by a high-sucrose (HS) diet or fat deposition induced by high-fat feeding. We aimed to determine the effects of high protein intake on the development of fat deposition and partitioning in response to high-fat and/or HS feeding. A total of thirty adult male Wistar rats were assigned to one of the six dietary regimens with low and high protein, sucrose and fat contents for 5 weeks. Body weight (BW) and food intake were measured weekly. Oral glucose tolerance tests and meal tolerance tests were performed after 4th and 5th weeks of the regimen, respectively. At the end of the study, the rats were killed 2 h after ingestion of a calibrated meal. Blood, tissues and organs were collected for analysis of circulating metabolites and hormones, body composition and mRNA expression in the liver and adipose tissues. No changes were observed in cumulative energy intake and BW gain after 5 weeks of dietary treatment. However, high-protein diets reduced by 20 % the adiposity gain induced by HS and high-sucrose high-fat (HS-HF) diets. Gene expression and transcriptomic analysis suggested that high protein intake reduced liver capacity for lipogenesis by reducing mRNA expressions of fatty acid synthase (fasn), acetyl-CoA carboxylase a and b (Acaca and Acacb) and sterol regulatory element binding transcription factor 1c (Srebf-1c). Moreover, ketogenesis, as indicated by plasma β-hydroxybutyrate levels, was higher in HS-HF-fed mice that were also fed high protein levels. Taken together, these results suggest that high-protein diets may reduce adiposity by inhibiting lipogenesis and stimulating ketogenesis in the liver. Adult male Wistar rats were fed diets with varying amounts of protein, carbohydrates and fat for 5 weeks. At the end of the experiment, rats were killed and tanscriptome analysis was performed on pooled liver samples.

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Gene expression-based comparison of PQQ and known transcriptional regulators

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