Project description:Objective Recent evidence indicates that the adult hematopoietic system is susceptible to diet-induced lineage skewing. It is not known whether the developing hematopoietic system is subject to metabolic programming via in utero high fat diet (HFD) exposure, an established mechanism of adult disease in several organ systems. We previously reported substantial losses in offspring liver size with prenatal HFD. As the liver is the main hematopoietic organ in the fetus, we asked whether the developmental expansion of the hematopoietic stem and progenitor cell (HSPC) pool is compromised by prenatal HFD and/or maternal obesity. Methods We used quantitative assays, progenitor colony formation, flow cytometry, transplantation, and gene expression assays with a series of dietary manipulations to test the effects of gestational high fat diet and maternal obesity on the day 14.5 fetal liver hematopoietic system. Results Maternal obesity, particularly when paired with gestational HFD, restricts physiological expansion of fetal HSPCs while promoting the opposing cell fate of differentiation. Importantly, these effects are only partially ameliorated by gestational dietary adjustments for obese dams. Competitive transplantation reveals compromised repopulation and myeloid-biased differentiation of HFD-programmed HSPCs to be a niche-dependent defect, apparent in HFD-conditioned male recipients. Fetal HSPC deficiencies coincide with perturbations in genes regulating metabolism, immune and inflammatory processes, and stress response, along with downregulation of genes critical for hematopoietic stem cell self-renewal and activation of pathways regulating cell migration. Conclusions Our data reveal a previously unrecognized susceptibility to nutritional and metabolic developmental programming in the fetal HSPC compartment, which is a partially reversible and microenvironment-dependent defect perturbing stem and progenitor cell expansion and hematopoietic lineage commitment. Examination of differentially expressed genes between gestational day 15 (+/- 0.5 days) C57BL/6 mouse fetal livers from diet-induced (60% fat diet) obese or control female mice.
Project description:Obesity is associated with an increased incidence of high grade prostate cancer (PC) and worse prognosis for PC patients. Recently, we showed in men that obesity-related periprostatic white adipose tissue (WAT) inflammation, characterized by macrophages surrounding dead or dying adipocytes forming crown-like structures, was associated with high grade PC. Possibly, interventions that suppress periprostatic WAT inflammation will improve outcomes for men with PC. Prior to testing interventions we conducted this study to identify transcriptomic differences in periprostatic fat from lean and obese mice. We hypothesized that periprostatic fat from obese mice would have a proinflammatory signature in gene expression pattern. To test our hypothesis that obese mice would develop molecular signatures of inflammation in periprostatic fat, we fed mice low fat diet or high fat diet for 12 weeks and then harvested periprostatic fat at sacrifice. RNA was isolated and analyzed from 5 lean and 5 obese mice and analyzed by microarray.
Project description:Rodents respond to chronic high fat diet in at least two ways: some of them may readily gain body weight and become obese (termed obesity-prone), and others may not (termed obesity-resistant). An integrated approach of transcript and metabolic profiling of obesity-prone and obesity-resistant rats has been conducted, showing significantly different transcript and metabolic profiles in the two phenotypes. The major transcriptional differences involved hepatic fatty acid metabolism and ketogenesis in response to 16 weeks of high fat diet. At the same time, the different metabolic profiles (in liver tissue extracts, serum, and urine) between the two phenotypes could be ascribed to the corresponding pathways identified with multivariate statistical analysis, including fatty acid metabolism, Krebs cycle, and amino acid metabolism. The integration of results from both transcript and metabolic profiling revealed the different responses to dietary intervention of the two phenotypes and the physiological basis of susceptibility to metabolic disease in obesity-prone rats from a systematic view.
Project description:Background: Post-menopausal obesity is an established risk factor for breast cancer. Consumption of diets high in fat is known to be highly correlated with obesity. In this, we sought to evaluate the interaction(s) between high fat diet, weight gain and mammary carcinogenesis using an obese-resistant and obese-prone rat model with direct correlates to human disease. Methods: Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly. Results: The DMBA-treated OR rats on the 39% safflower diet had significantly greater incidence of ductal carcinoma-in-situ (DCIS) lesions and significantly greater DCIS multiplicity than DMBA-treated OR rats on the 10% safflower diet. These differences were not seen in the OP strain. Gene expression analysis of mammary ductal epithelium from OR rats on the high fat diet showed significant upregulation of proliferation-related genes compared to those consuming the low fat safflower diet. Again, these differences were not seen in the OP strain. Conclusion: Our findings indicate that consumption of high fat safflower diet enhances mammary carcinogenesis in an OR rat strain through increased proliferation of mammary epithelium at the time of exposure, but not in the OP rat strain. Thus, the diet-induced increase in sensitivity was strain-specific and independent of weight gain or obesity level. Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly.
Project description:Analysis of GPR120 which play roles for the fatty acid sensor in adipose tissue. Results provide insight into the transcriptional effects caused by the loss of the GPR120 proteins and provide further insight into their functions. GPR120 KO mice and the corresponding wild-type with normal diet(ND) or high fat diet(HFD), were subjected to Affymetrix Mus musculus microarrays. Epididymal adipose tissue and liver were analyzed in triplicates.
Project description:High-fat diet (HFD) decreases insulin sensitivity. How high-fat diet causes insulin resistance is largely unknown. Here, we show that lean mice become insulin resistant after being administered exosomes isolated from the feces of obese mice fed a high-fat diet (HFD) or from human type II diabetic patients with diabetes. HFD altered the lipid composition of exosomes from predominantly PE in exosomes from lean animals (L-Exo) to PC in exosomes from obese animals (H-Exo). Mechanistically, we show that intestinal H-Exo is taken up by macrophages and hepatocytes, leading to inhibition of the insulin signaling pathway. Moreover, exosome-derived PC binds to and activates AhR, leading to inhibition of the expression of genes essential for activation of the insulin signaling pathway, including IRS-2, and its downstream genes PI3K and Akt. Together, our results reveal HFD-induced exosomes as potential contributors to the development of insulin resistance. Intestinal exosomes thus have potential as broad therapeutic targets.
Project description:Obesity is a highly heritable complex disease that results from the interaction of multiple genetic and environmental factors. Formerly obese individuals are susceptible to metabolic disorders later in life, even after lifestyle changes are made to mitigate the obese state. This is reminiscent of the metabolic memory phenomenon originally observed for persistent complications in diabetic patients, despite subsequent glycemic control. Epigenetic modifications represent a potential mediator of this observed memory. We previously demonstrated that a high fat (HF) diet leads to changes in chromatin accessibility in the mouse liver. The regions of greatest chromatin changes in accessibility are largely strain dependent, indicating a genetic component in diet-induced chromatin alterations. We have now examined the persistence of diet-induced chromatin accessibility changes upon diet reversal in two strains of mice. We find that a substantial fraction of loci that undergo chromatin accessibility changes with HF diet remain in the remodeled state after diet reversal in C57BL/6J mice. In contrast, the vast majority of diet-induced chromatin accessibility changes in A/J mice are transient. Our data also indicate that the persistent chromatin accessibility changes observed in C57BL/6J are associated with specific transcription factors and histone posttranslational modifications. The persistent loci identified here are likely to be contributing to the overall phenotype and are attractive targets for therapeutic intervention. Examination of chromatin remodeling with FAIRE-seq in livers of C57BL/6J and A/J mice on three diet regimen: 1) control diet for 16 weeks, 2) high fat diet for 16 weeks, or 3) high fat diet for 8 weeks with control diet for 8 weeks. These chromatin profiles were complemented with gene expression data (RNA-seq)
Project description:The popularity of high fat foods in modern society has been associated with epidemic of various metabolic diseases characterized by insulin resistance, the pathology of which involves complex interactions between multiple tissues such as liver, skeletal muscle and white adipose tissue (WAT). To uncover the mechanism by which excessive fat impairs insulin sensitivity, we conducted a multi- tissue study by using TMT-based quantitative proteomics. 3-week-old ICR mice were fed with high fat diet (HFD) for 19 weeks to induce insulin resistance. Liver, skeletal muscle and epididymal fat were collected for proteomics screening. Additionally, PRM was used for validating adipose differential proteins. By comparing tissue-specific protein profiles of HFD mice, multi-tissue regulation of glucose and lipid homeostasis and corresponding underlying mechanisms was systematically investigated and characterized. NC: normal birth weight + chow diet; NH: normal birth weight + high fat diet; LC: low birth weight + chow diet; LH: low birth weight + high fat diet.
Project description:Background: Post-menopausal obesity is an established risk factor for breast cancer. Consumption of diets high in fat is known to be highly correlated with obesity. In this, we sought to evaluate the interaction(s) between high fat diet, weight gain and mammary carcinogenesis using an obese-resistant and obese-prone rat model with direct correlates to human disease. Methods: Female obese-prone (OP) and obese-resistant (OR) weanling rats were placed on either a low fat (10% kcal) or a high fat (39% kcal) n-6 polyunsaturated (PUFA) safflower diet for 30 days. At post natal day (PND) 50, global gene expression profiling was performed on microdissected mammary epithlelium from one cohort of rats and another cohort of rats were given a single oral gavage of either 7,12-dimethylbenz[a]anthracene (DMBA at 14 mg/kg) or vehicle. Rats were then maintained on the diets and body weights, food consumption and development of mammary lesions were monitored weekly. Results: The DMBA-treated OR rats on the 39% safflower diet had significantly greater incidence of ductal carcinoma-in-situ (DCIS) lesions and significantly greater DCIS multiplicity than DMBA-treated OR rats on the 10% safflower diet. These differences were not seen in the OP strain. Gene expression analysis of mammary ductal epithelium from OR rats on the high fat diet showed significant upregulation of proliferation-related genes compared to those consuming the low fat safflower diet. Again, these differences were not seen in the OP strain. Conclusion: Our findings indicate that consumption of high fat safflower diet enhances mammary carcinogenesis in an OR rat strain through increased proliferation of mammary epithelium at the time of exposure, but not in the OP rat strain. Thus, the diet-induced increase in sensitivity was strain-specific and independent of weight gain or obesity level.