Sex-dependent effects of Siah2 on brown adipose tissue whitening and inflammation with a high fat diet
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE123990 | GEO | 2019/04/25
REPOSITORIES: GEO
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Project description:Sex-dependent effects of Siah2 on brown adipose tissue whitening and inflammation with a high fat diet
| PRJNA510432 | ENA
Project description:Chronic, low-grade adipose tissue inflammation associated with adipocyte hypertrophy is an important link in the relationship between obesity and insulin resistance. Although ubiquitin ligases are essential regulators of inflammatory processes, the role of these enzymes in metabolically driven adipose tissue inflammation is relatively unexplored. In this study, we found that the ubiquitin ligase Siah2 is a central factor in obesity-related adipose tissue inflammation. When challenged with chronic excess energy intake, Siah2-null mice become obese with enlarged adipocytes, but do not develop obesity-induced insulin resistance. Proinflammatory gene expression is substantially reduced in the Siah2-null epididymal adipose tissue of the obese Siah2KO mice.
2015-09-29 | GSE61839 | GEO
Project description:In mammals, white adipose tissue (WAT) stores and releases lipids, whereas brown adipose tissue (BAT) oxidizes lipids to fuel thermogenesis. In obese individuals, WAT undergoes profound changes; it expands, becomes dysfunctional, and develops a low-grade inflammatory state. Importantly, BAT content and activity decline in obese subjects, mainly as a result of the conversion of brown adipocytes to white-like unilocular cells. Here, we show that BAT "whitening" is induced by multiple factors, including high ambient temperature, leptin receptor deficiency, β-adrenergic signaling impairment, and lipase deficiency, each of which is capable of inducing macrophage infiltration, brown adipocyte death, and crown-like structure (CLS) formation. Brown-to-white conversion and increased CLS formation were most marked in BAT from adipose triglyceride lipase (Atgl)-deficient mice, where, according to transmission electron microscopy, whitened brown adipocytes contained enlarged endoplasmic reticulum, cholesterol crystals, and some degenerating mitochondria, and were surrounded by an increased number of collagen fibrils. Gene expression analysis showed that BAT whitening in Atgl-deficient mice was associated to a strong inflammatory response and NLRP3 inflammasome activation. Altogether, the present findings suggest that converted enlarged brown adipocytes are highly prone to death, which, by promoting inflammation in whitened BAT, may contribute to the typical inflammatory state seen in obesity.
| S-EPMC5928436 | biostudies-literature
Project description:BackgroundThe obesity-related risk of developing metabolic syndrome is higher in males than in females of reproductive age, likely due to estrogen-mediated reduced adipose tissue inflammation and fibrosis with hypertrophied adipocytes. Depletion of the ubiquitin ligase Siah2 reduced white adipose tissue inflammation and improved glucose metabolism in obese male mice. Siah2 is a transcriptional target of estrogen, but data is lacking about the effect of Siah2 on adipose tissue of females. We therefore evaluated the impact of Siah2 deficiency on white and brown adipose tissue in females of reproductive age.MethodsBody composition, adipose tissue morphology, brown adipose tissue gene, and protein expression and adipocyte sizing were evaluated in wild-type and Siah2KO female and male mice fed a low-fat or high-fat diet. Glucose and insulin tolerance, fasting glucose, insulin, fatty acids and triglycerides, and gene expression of inflammation markers in perigonadal fat were evaluated in wild-type and Siah2KO female mice. Microarray analysis of brown fat gene expression was carried out in both sexes. Statistical analysis was assessed by unpaired two-tailed t test and repeated measures ANOVA.ResultsSiah2 deficiency improves glucose and insulin tolerance in the presence of hypertrophied white adipocytes in high-fat-fed female mice with percent fat comparable to male mice. While previous studies showed Siah2KO reduces the white adipose tissue inflammatory response in male mice, the response in females is biased toward the upregulation of M2-like markers in white adipose tissue. In contrast, loss of Siah2 leads to increased whitening of brown fat in males, but not in females. This corresponded to increased expression of markers of inflammation (F4/80, Ccl2) and thermogenic genes (Pgc1alpha, Dio2, Ucp-1) and proteins (PGC-1α, UCP-1) in females. Contrary to expectations, increased expression of thermogenic markers in females was coupled with a downregulation of ERalpha and ERRgamma protein levels.ConclusionsThe most striking sex-related effect of Siah2 deficiency is reduced whitening of brown fat in high-fat-fed females. Protection from accumulating unilocular adipocytes in the brown fat corresponds to increased expression of thermogenic genes and proteins in female, but not in male mice. These results raise the possibility that Siah2 contributes to the estrogen-related effects on brown fat function in males and females.
| S-EPMC6466809 | biostudies-literature
Project description:Brown adipose tissue (BAT) is a highly vascularized organ with abundant mitochondria that produce heat through uncoupled respiration. Obesity is associated with a reduction of BAT function; however, it is unknown how obesity promotes dysfunctional BAT. Here, using a murine model of diet-induced obesity, we determined that obesity causes capillary rarefaction and functional hypoxia in BAT, leading to a BAT “whitening” phenotype that is characterized by mitochondrial dysfunction, lipid droplet accumulation, and decreased expression of Vegfa. Targeted deletion of Vegfa in adipose tissue of nonobese mice resulted in BAT whitening, supporting a role for decreased vascularity in obesity-associated BAT. Conversely, introduction of VEGF-A specifically into BAT of obese mice restored vascularity, ameliorated brown adipocyte dysfunction, and improved insulin sensitivity. The capillary rarefaction in BAT that was brought about by obesity or Vegfa ablation diminished β-adrenergic signaling, increased mitochondrial ROS production, and promoted mitophagy. These data indicate that overnutrition leads to the development of a hypoxic state in BAT, causing it to whiten through mitochondrial dysfunction and loss. Furthermore, these results link obesity-associated BAT whitening to impaired systemic glucose metabolism.
2024-12-18 | GSE221854 | GEO
Project description:Following publication of the original article [1], the authors reported that additional file 1 was incorrect. The corrected additional file 1 is given below.
| S-EPMC6643305 | biostudies-literature
Project description:Gene expression profiling was performed to identify Siah2-dependent changes in cells subjected to ER stress, hypoxia, and combined glucose/oxygen deprivation. To establish the magnitude of the Siah2 effect on the ER stress response, we have compared gene expression profiles of WT and Siah1a-/-::Siah2-/- mouse embryo fibroblasts (MEFs) that were subjected to glycosylation inhibitor tunicamycin (TM), thapsigargin (TG), glucose deprivation, or glucose/oxygen deprivation. Overall, this analysis confirmed changes associated with ER stress that had not previously been associated with Siah2 signaling, substantiating Siah2 as a key coordinator of ER stress through the ATF4 and sXbp1 pathways. WT and Siah1a/Siah2 KO MEF cells were treated with TM or TG for 6 h, or subjected for 12 h to oxygen deprivation, glucose deprivation or a combination of oxygen and glucose deprivation, in duplicate.
2014-04-01 | E-GEOD-39244 | biostudies-arrayexpress
Project description:Gene expression profiling was performed to identify Siah2-dependent changes in cells subjected to ER stress, hypoxia, and combined glucose/oxygen deprivation. To establish the magnitude of the Siah2 effect on the ER stress response, we have compared gene expression profiles of WT and Siah1a-/-::Siah2-/- mouse embryo fibroblasts (MEFs) that were subjected to glycosylation inhibitor tunicamycin (TM), thapsigargin (TG), glucose deprivation, or glucose/oxygen deprivation. Overall, this analysis confirmed changes associated with ER stress that had not previously been associated with Siah2 signaling, substantiating Siah2 as a key coordinator of ER stress through the ATF4 and sXbp1 pathways.
2014-04-01 | GSE39244 | GEO
Project description:Understanding mechanisms underlying anti-tumor immunity is pivotal for improving immune-based cancer therapies. Here we demonstrate that growth of inoculated BRAF mutant melanoma cells was inhibited in Siah2-/- mice, up to a complete loss. Melanoma grown in Siah2-/- mice exhibited increased proinflammatory immune components, signified by enhanced intra-tumoral activated T cells, along with decreased expression of Ccl17 and Ccl22, and decreased Foxp3 expression. A marked reduction in Treg proliferation was associated with inhibition of Treg cell cycle progression. Correspondingly, G1 cell cycle arrest in Siah2-/- Tregs coincided with elevated expression of the cyclin dependent kinase inhibitor p27, a Siah2 substrate. Growth of PD1-unresponsive melanoma was effectively inhibited up to complete tumor rejection in Siah2-/- mice subjected to PD1 blockade, highlighting synergy between PD1 inhibition and Siah2 loss. Siah2 regulation of Treg recruitment and cell cycle progression effectively controls melanoma development and confers synthetic lethality when combined with anti-PD1 therapy.
2019-07-18 | GSE134412 | GEO
Project description:Maternal high fat diet may disturb susceptibility in offspring. Brown adipose tissue from maternal high fat diet has CpG sites that exhibit differential DNA methylationregulated compared to control.
2021-07-26 | GSE173218 | GEO