Diet-induced obesity (DIO) is rapidly becoming a global health problem, particularly as Westernization of emerging nations continues. Currently, one third of adult Americans are considered obese and, if current trends continue, >90% of US citizens are predicted to be affected by 2050. However, efforts to fight this epidemic have not yet produced sound solutions for prevention or treatment. Our studies reveal a balanced and chronobiological relationship between food consumption, daily variation in gut microbial evenness and function, basomedial hypothalamic circadian clock (CC) gene expression, and key hepatic metabolic regulatory networks , including CC and nuclear receptors (NR), that is are essential for metabolic homeostasis. Western diets high in saturated fats dramatically alter diurnal variation in microbial composition and function, which in turn lead to uncoupling of the hepatic CC and NR networks from central CC control in ways that offset the timing and types of regulatory factors directing metabolic function. These signals include microbial metabolites such as short chain fatty acids (SCFAs) and hydrogen sulfide (H2S) that can directly regulate or disrupt metabolic networks of the hepatocyte. Our study therefore provides insights into the complex and dynamic relationships between diet, gut microbes, and the host that are critical for maintenance of health. Perturbations of this constellation of processes, in this case by diet-induced dysbiosis and its metabolomic signaling, can potentially promote metabolic imbalances and disease. This knowledge opens up many possibilities for novel therapeutic and interventional strategies to treat and prevent DIO, ranging from the manipulation of gut microbial function to pharmacological targeting of host pathways to restore metabolic balance.
Effects of diurnal variation of gut microbes and high-fat feeding on host circadian clock function and metabolism.
Specimen part
View SamplesOsteosarcoma (OS) is the malignant bone tumor with a high tendency to metastasize to the lung, where the molecular mechanisms are unclear. The mouse OS cell line LM8 has been isolated originally from the Dunn OS cell line by in vivo selection as a subline with a high metastatic potential to the lung.
Stable knockdown of S100A4 suppresses cell migration and metastasis of osteosarcoma.
Cell line
View SamplesDietary polyunsaturated fatty acids (PUFA) act as potent natural hypolipidemics and are linked to many health benefits in humans and in animal models. Mice fed long-term a high fat diet, in which medium-chain alpha linoleic acid (ALA) was partially replaced by long-chain docosahexaenoic (DHA) and eicosapentaenoic (EPA) fatty acids, showed reduced accumulation of body fat and prevention of insulin resistance, besides increased mitochondrial beta-oxidation in white adipose tissue and decreased plasma lipids. ALA, EPA and DHA all belong to PUFA of n-3 series. The intestine is a gatekeeper organ for ingested lipids. To examine the potential contribution of the intestine in the beneficial effects of EPA and DHA, this study assessed gene expression changes using whole genome microarray analysis on small intestinal scrapings. The main biological process affected was lipid metabolism. Fatty acid uptake, peroxisomal and mitochondrial beta-oxidation, and omega-oxidation of fatty acids were all increased. Quantitative real time PCR and intestinal fatty acid oxidation measurements ([14C(U)]-palmitate) confirmed significant gene expression differences in a dose-dependent manner. Furthermore, no major changes in the expression of lipid metabolism genes were observed in colonic scrapings. In conclusion, we show that marine n-3 fatty acids regulate small intestinal gene expression patterns. Since this organ contributes significantly to whole organism energy use, this adaptation of the small intestine may contribute to the complex and observed beneficial physiological effects of these natural compounds under conditions that will normally lead to development of obesity and diabetes.
Induction of lipid oxidation by polyunsaturated fatty acids of marine origin in small intestine of mice fed a high-fat diet.
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View SamplesHomozygous disruption of c-Maf led to embryonic lethality and impaired erythroblastic island formation. c-Maf is expressed in the fetal liver macrophages. It suggests that macrophages are responsible for the lethality of c-Maf knock-out embryos. To search downstream genes of c-Maf, we surveyed genes associated with macrophage function by microarray analysis.
c-Maf plays a crucial role for the definitive erythropoiesis that accompanies erythroblastic island formation in the fetal liver.
Specimen part
View SamplesThe onset of the liver inflamentation in the Sox17+/- embryos.
Sox17 haploinsufficiency results in perinatal biliary atresia and hepatitis in C57BL/6 background mice.
Specimen part
View SamplesBox C/D-type small nucleolar RNAs (snoRNAs) are functional RNAs responsible for mediating 2-O-ribose methylation of ribosomal RNAs (rRNAs) within the nucleolus. Previously, in relation to a novel chromosomal translocation in a human B-cell lymphoma, we identified U50HG, a non-protein-coding gene that hosted a box C/D-type U50 snoRNA within its intron. To investigate the physiological importance of the U50 snoRNA and its involvement in tumorigenesis, we generated a mouse model deficient in mouse U50 (mU50) snoRNA expression without altering the expression of mouse mU50 host-gene, mU50HG-b. The established mU50 snoRNA-deficient mice showed a significant reduction of mU50 snoRNA expression and the corresponding target rRNA methylation in various organs. Lifelong phenotypic monitoring showed that the mU50-deficient mice looked almost normal without accelerated tumorigenicity; however, a notable difference was the propensity for anomalies in the lymphoid organs.
Generation of a mouse model with down-regulated U50 snoRNA (SNORD50) expression and its organ-specific phenotypic modulation.
Specimen part
View SamplesEpigenetic gene regulation in various oncogenic pathways is currently an important focus of cancer research. The PI3K pathway plays a pivotal role in hepatocellular carcinoma, but the significance of histone modification in the PI3K pathway-dependent hepatotumorigenesis remains unknown.
Impact of histone demethylase KDM3A-dependent AP-1 transactivity on hepatotumorigenesis induced by PI3K activation.
Specimen part
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