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:As early as one month of age, nonobese diabetic (NOD) mice feature pancreatic infiltration of autoreactive T lymphocytes, which destruct insulin-producing beta cells, producing autoimmune diabetes mellitus (T1D) within eightmonths. Thus, we hypothesized that during the development of T1D, the transcriptional modulation of immune reactivity genes may occur as thymocytes mature into peripheral T lymphocytes. The transcriptome of thymocytes and peripheral CD3+ T lymphocytes from prediabetic or diabetic mice analyzed through microarray hybridizations identified the differentially expressed genes.
Project description:As early as one month of age, nonobese diabetic (NOD) mice feature pancreatic infiltration of autoreactive T lymphocytes, which destruct insulin-producing beta cells, producing autoimmune diabetesmellitus (T1D) within eight months. Thus, we hypothesized that during the development of T1D, the transcriptional modulation of immune reactivity genes may occur as thymocytes mature into peripheral T lymphocytes. The transcriptome of thymocytes and peripheral CD3+ T lymphocytes from prediabetic or diabetic mice analyzed through microarray hybridizations identified the differentially expressed genes.
Project description:Little is known about how pro-obesity diets regulate tissue stem and progenitor cell function. Here we find that high fat diet (HFD)-induced obesity augments the numbers and function of Lgr5+ intestinal stem cells (ISCs) of the mammalian intestine. Like HFD, ex vivo treatment of intestinal organoid cultures with palmitic acid (PA), a constituent of the HFD, enhances the self-renewal potential of these organoid bodies. Mechanistically, HFD induces a robust peroxisome proliferator-activated receptor delta (PPAR-delta signature in intestinal stem and progenitor cells and pharmacologic activation of PPAR-delta recapitulates the effects that HFD has on these cells. Interestingly, HFD- and agonist-activated PPAR-delta signaling endows organoid-initiating capacity to non-stem cells and enforced PPAR-delta signaling permits these non-stem cells to form in vivo tumors upon loss of the tumor suppressor Apc. These findings highlight how diet-modulated PPAR-delta activation alters not only the function of intestinal stem and progenitor cells but also their capacity to initiate tumors. mRNA profiles of intestinal stem cells (GFP-Hi) and progenitors (GFP-Low) from WT or HFD fed mice were generated by deep sequencing using HiSeq 2000.
Project description:We employed high-fat diet (HFD)-induced prediabetes and HFD/streptozotocin (STZ)-induced type 2 diabetes mouse models that develop PN, which we compared to control mice maintained on standard diet (SD) and to HFD and HFD/STZ mice that were subject to SD dietary reversal (DR) half-way through the study. We performed gene expression profiling on sciatic nerves from SD, HFD, HFD-STZ, HFD-DR, and HFD-STZ-DR animal cohorts. Nerve transcriptomic profiles were integrated using complex correlation analyses, and biological meaning was inferred from known lipid-gene interactions in the literature
Project description:Neuroinflammation is associated with neurodegenerative diseases, including Alzheimer’s and Parkinson’s. The cytokine interleukin-12 activates signal transducer and activator of transcription 4 (Stat4), consumption of a high-fat, high-cholesterol diet (HFD-C) and Stat4 activity are associated with inflammation, atherosclerosis, and a diabetic metabolic phenotype. In studies of in vitro hippocampal slices from control Stat4fl/flLdlr-/- mice fed a HFD-C diabetogenic diet, we found that Schaffer collateral-CA1 synapses exhibited larger reductions in activity-dependent, long-term potentiation (LTP) of synaptic transmission, compared to mice fed a standard diet. Glucose tolerance and insulin sensitivity shifts produced by HFD-C diet were reduced in Stat4ΔLysMLdlr-/- mice compared to Stat4fl/flLdlr-/- controls. Stat4ΔLysMLdlr-/- mice, which lack Stat4 under control of the LysMCre promoter, were resistant to HFD-C induced impairments in LTP. In contrast, Schaffer collateral-CA1 synapses in Stat4ΔLysMLdlr-/- mice fed the HFD-C diet showed larger LTP than control Stat4fl/flLdlr-/- mice. Expression of a number of neuroinflammatory and synaptic plasticity genes was reduced by HFD-C diet in control mice, and less affected by HFD-C diet in Stat4ΔLysMLdlr-/- mice. Suppression of Stat4 activation has potential for protecting against effects of western diet on cognition, type 2 diabetes, and reduce risk of Alzheimer’s disease and other neurodegenerative disorders associated with neuroinflammation.
Project description:High dietary fat intake is a major risk factor for the development of obesity, which is frequently associated with diabetes. To identify genes involved in diabetic nephropathy, GeneChip Expression Analysis was employed to survey the glomerular gene expression profile in diabetic KK/Ta mice fed with a high-fat diet (HFD). Isolated glomeruli from three 20-week-old KK/Ta mice fed with HFD (HFD group) or a normal fat diet (Chow group) were dissected. Total RNA was extracted and labeled for hybridization using the Affymetrix GeneChip Mouse Genome 430 2.0 Array. The gene expression profile was compared between the HFD and Chow groups using GeneSpring 7.3.1 software.
Project description:Background: Epigenetic alteration of the genome has been shown to provide palliative effects in mouse models of certain human autoimmune disorders. We have investigated whether chromatin remodeling could provide protection against autoimmune diabetes in nonobese diabetic (NOD) mice. Treatment of female mice during the transition from prediabetic to diabetic stage (18-24 weeks of age) with the well-characterized histone deacetylase inhibitor, Trichostatin A (TSA) effectively reduced the incidence of diabetes and abrogated the ability of splenocytes to adoptively transfer the disease into immunodeficient NOD.scid mice. Protection against diabetes was accompanied by histone hyperacetylation in pancreas and spleen, increased frequency of CD4+ CD62L+ cells in the spleen, reduction in cellular infiltration of islets, restoration of normoglycemia and glucose-induced insulin release by beta cells. In vitro activation of splenic T lymphocytes derived from protected mice resulted in enhanced expression of IFN-gamma mRNA and protein without altering the expression of Il4, Il17, Il18, Inos, and Tnfa genes nor the secretion of IL-2, IL-4, IL-17 and TNF-alpha proteins. Consistently, expression of the transcription factor involved in Ifng transcription, Tbet/Tbx21 but not Gata3 and Rorgt, respectively required for the transcription of Il4 and Il17, was upregulated in activated splenocytes of protected mice. These data indicate that abrogation of autoimmune diabetes is associated with the selective upregulation of certain inducible genes in T lymphocytes. Microarray analysis was performed to determine the changes in global gene expression underlying abrogation of autoimmune diabetes by TSA-mediated epigenetic modulation and identified a distinct group of genes down-regulated during this process. Female NOD mice were treated subcutaneously with TSA (500 µg/Kg body weight) during the transition from prediabetic to diabetic stage (18-24 weeks of age), at weekly intervals. Since we sought to determine the modulation of global gene expression associated with long-term protection against diabetes, TSA treated mice were killed between 32 and 36 weeks of age and total RNA was extracted from uninduced splenocytes. RNA was also extracted from splenocytes of untreated mice that became diabetic and those that did not develop diabetes till 36 weeks of age. Blood glucose levels were determined weekly to monitor the glycemic condition in untreated and TSA-treated mice. To minimize the variability in gene expression among individual mice, RNA was extracted from splenocytes of 3 to 5 mice per group and pooled. Each sample was hybridized to microchips in duplicate. Female NOD mice were treated with Trichostatin A (500 µg/Kg body weight) between 18-24 weeks of age or left untreated.