Adiposity In Female Mice Research Articles

NLRC5 affects diet-induced adiposity in female mice and co-regulates peroxisome proliferator-activated receptor PPARγ target genes

Nucleotide-binding and oligomerization domain containing 5 (NLRC5) is the key transcriptional regulator of major histocompatibility (MHC) class I genes. Recent observations suggest a role for NLRC5 in metabolic traits and in transcriptional regulation beyond MHC class I genes. To understand the function of NLRC5 in metabolic disease, we subjected Nlrc5 -/- mice to high-fat diet (HFD) feeding. Female Nlrc5 -/- mice presented with higher weight gain and more adipose tissue (AT) compared to wild-type (WT) animals. Mechanistically, we demonstrate that NLRC5 enhanced the expression of peroxisome proliferator-activated receptor (PPAR) γ target genes in human cells. We identify Sin3A and negative elongation factor (NELF) B as two novel NLRC5 interaction partners and show that Sin3A partly modulates the synergistic transcriptional effect of NLRC5 on PPARγ. Collectively, we show that NLRC5 contributes to weight gain in mice, which involves transcriptional enhancement of PPARγ targets by NLRC5 that is co-regulated by Sin3A.

LBODP005 Gper Modulates Multiple Functions In Adipose Tissue To Promote An Anti-obese Phenotype

Abstract Obesity and metabolic syndrome are major health issues of modern society and their incidence is increasing at alarming rates worldwide. Obesity and associated chronic diseases exhibit sexual disparity with pre-menopausal females displaying better protection compared to age-matched males. These beneficial effects on metabolism in females are predominantly attributed to the female hormone estrogen, specifically 17β-estradiol (E2). E2 exerts its actions via multiple receptors, nuclear and extra-nuclear estrogen receptor (ER) α and ERβ, and the G protein-coupled estrogen receptor (GPER). GPER is present in diverse cells types and tissues and has been implicated in numerous physiological processes via multiple cellular signaling pathways. We have combined in vivo studies in an ovariectomized (OVX) mouse model along with in vitro assays in 3T3-L1 cells to investigate the role of GPER in modulating adipocyte function. Our studies reveal that loss of GPER increased adiposity in female mice on high fat diet and activation of GPER by its selective agonist G-1 attenuates adiposity in OVX mice. G-1 activated AMPK, increased cellular respiration and expression of mitochondrial and antioxidant genes and reduced lipid deposition in adipocytes. Furthermore, G-1 treatment promoted an anti-inflammatory phenotype in mice. Thus, our findings establish a role of GPER agonist G-1 in exerting anti-lipogenic and anti-inflammatory effects in adipocytes, which may have potential therapeutic implications in treatment of obesity. Presentation: No date and time listed

Leptin and environmental temperature as determinants of bone marrow adiposity in female mice.

Bone marrow adipose tissue (BMAT) levels are higher in distal femur metaphysis of female mice housed at thermoneutral (32°C) than in mice housed at 22°C, as are abdominal white adipose tissue (WAT) mass, and serum leptin levels. We performed two experiments to explore the role of increased leptin in temperature-enhanced accrual of BMAT. First, we supplemented 6-week-old female C57BL/6J (B6) mice with leptin for 2 weeks at 10 µg/d using a subcutaneously implanted osmotic pump. Controls consisted of ad libitum (ad lib) fed mice and mice pair fed to match food intake of leptin-supplemented mice. The mice were maintained at 32°C for the duration of treatment. At necropsy, serum leptin in leptin-supplemented mice did not differ from ad lib mice, suggesting suppression of endogenous leptin production. In support, Ucp1 expression in BAT, percent body fat, and abdominal WAT mass were lower in leptin-supplemented mice. Leptin-supplemented mice also had lower BMAT and higher bone formation in distal femur metaphysis compared to the ad lib group, changes not replicated by pair-feeding. In the second experiment, BMAT response was evaluated in 6-week-old female B6 wild type (WT), leptin-deficient ob/ob and leptin-treated (0.3 μg/d) ob/ob mice housed at 32°C for the 2-week duration of the treatment. Compared to mice sacrificed at baseline (22°C), BMAT increased in ob/ob mice as well as WT mice, indicating a leptin independent response to increased temperature. However, infusion of ob/ob mice with leptin, at a dose rate having negligible effects on either energy metabolism or serum leptin levels, attenuated the increase in BMAT. In summary, increased housing temperature and increased leptin have independent but opposing effects on BMAT in mice.

Deletion of GPR30 Drives the Activation of Mitochondrial Uncoupling Respiration to Induce Adipose Thermogenesis in Female Mice.

Thermogenic adipocytes possess a promising approach to combat obesity with its capability promoting energy metabolism. We previously discovered that deletion of GPR30 (GPRKO), a presumably membrane-associated estrogen receptor, protected female mice from developing obesity, glucose intolerance, and insulin resistance when challenged with a high-fat diet (HFD). In vivo, the metabolic phenotype of wild type (WT) and GPRKO female mice were measured weekly. Acute cold tolerance test was performed. Ex vivo, mitochondrial respiration of brown adipose tissue (BAT) was analyzed from diet-induced obese female mice of both genotypes. In vitro, stromal vascular fractions (SVF) were isolated for beige adipocyte differentiation to investigate the role of GPR30 in thermogenic adipocyte. Deletion of GPR30 protects female mice from hypothermia and the mitochondria in BAT are highly energetic in GPRKO animals while the WT mitochondria remain in a relatively quiescent stage. Consistently, GPR30 deficiency enhances beige adipocyte differentiation in white adipose tissue (WAT) and activates the thermogenic browning of subcutaneous WAT due to up-regulation of UCP-1, which thereby protects female mice from HFD-induced obesity. GPR30 is a negative regulator of thermogenesis, which at least partially contributes to the reduced adiposity in the GPRKO female mice. Our findings provide insight into the mechanism by which GPR30 regulates fat metabolism and adiposity in female mice exposed to excess calories, which may be instrumental in the development of new therapeutic strategies for obesity.

Brown Fat Dnmt3b Deficiency Ameliorates Obesity in Female Mice.

Obesity results from a chronic energy imbalance due to energy intake exceeding energy expenditure. Activation of brown fat thermogenesis has been shown to combat obesity. Epigenetic regulation, including DNA methylation, has emerged as a key regulator of brown fat thermogenic function. Here we aimed to study the role of Dnmt3b, a DNA methyltransferase involved in de novo DNA methylation, in the regulation of brown fat thermogenesis and obesity. We found that the specific deletion of Dnmt3b in brown fat promotes the thermogenic and mitochondrial program in brown fat, enhances energy expenditure, and decreases adiposity in female mice fed a regular chow diet. With a lean phenotype, the female knockout mice also exhibit increased insulin sensitivity. In addition, Dnmt3b deficiency in brown fat also prevents diet-induced obesity and insulin resistance in female mice. Interestingly, our RNA-seq analysis revealed an upregulation of the PI3K-Akt pathway in the brown fat of female Dnmt3b knockout mice. However, male Dnmt3b knockout mice have no change in their body weight, suggesting the existence of sexual dimorphism in the brown fat Dnmt3b knockout model. Our data demonstrate that Dnmt3b plays an important role in the regulation of brown fat function, energy metabolism and obesity in female mice.

STAT5 ablation in AgRP neurons increases female adiposity and blunts food restriction adaptations

AgRP neurons are important players in the control of energy homeostasis and are responsive to several hormones. In addition, STAT5 signalling in the brain, which is activated by metabolic hormones and growth factors, modulates food intake, body fat and glucose homeostasis. Given that, and the absence of studies that describe STAT5 function in AgRP cells, the present study investigated the metabolic effects of Stat5a/b gene ablation in these neurons. We observed that STAT5 signalling in AgRP neurons regulates body fat in female mice. However, male and female STAT5-knockout mice did not exhibit altered food intake, energy expenditure or glucose homeostasis compared to control mice. The counter-regulatory response or glucoprivic hyperphagia induced by 2-deoxy-d-glucose treatment were also not affected by AgRP-specific STAT5 ablation. However, under 60% food restriction, AgRP STAT5-knockout mice had a blunted upregulation of hypothalamic Agrp mRNA expression and corticosterone serum levels compared to control mice, suggesting a possible role for STAT5 in AgRP neurons for neuroendocrine adaptations to food restriction. Interestingly, ad libitum fed knockout male mice had reduced Pomc and Ucp-1 mRNA expression compared to control group. Taken together, these results suggest that STAT5 signalling in AgRP neurons regulates body adiposity in female mice, as well as some neuroendocrine adaptations to food restriction.

STAT5 ablation in AgRP neurons increases female adiposity and blunts food restriction adaptations.

AgRP neurons are important players in the control of energy homeostasis and are responsive to several hormones. In addition, STAT5 signalling in the brain, which is activated by metabolic hormones and growth factors, modulates food intake, body fat and glucose homeostasis. Given that, and the absence of studies that describe STAT5 function in AgRP cells, the present study investigated the metabolic effects of Stat5a/b gene ablation in these neurons. We observed that STAT5 signalling in AgRP neurons regulates body fat in female mice. However, male and female STAT5-knockout mice did not exhibit altered food intake, energy expenditure or glucose homeostasis compared to control mice. The counter-regulatory response or glucoprivic hyperphagia induced by 2-deoxy-d-glucose treatment were also not affected by AgRP-specific STAT5 ablation. However, under 60% food restriction, AgRP STAT5-knockout mice had a blunted upregulation of hypothalamic Agrp mRNA expression and corticosterone serum levels compared to control mice, suggesting a possible role for STAT5 in AgRP neurons for neuroendocrine adaptations to food restriction. Interestingly, ad libitum fed knockout male mice had reduced Pomc and Ucp-1 mRNA expression compared to control group. Taken together, these results suggest that STAT5 signalling in AgRP neurons regulates body adiposity in female mice, as well as some neuroendocrine adaptations to food restriction.

Deletion of leptin receptors in vagal afferent neurons disrupts estrogen signaling, body weight, food intake and hormonal controls of feeding in female mice.

Deletion of the leptin receptor from vagal afferent neurons (VAN) using a conditional deletion (Nav1.8/LepRfl/fl) results in an obese phenotype with increased food intake and lack of exogenous cholecystokinin (CCK)-induced satiation in male mice. Female mice are partially protected from weight gain and increased food intake in response to ingestion of high-fat (HF) diets. However, whether the lack of leptin signaling in VAN leads to an obese phenotype or disruption of hypothalamic-pituitary-gonadal axis function in female mice is unclear. Here, we tested the hypothesis that leptin signaling in VAN is essential to maintain estrogen signaling and control of food intake, energy expenditure, and adiposity in female mice. Female Nav1.8/LepRfl/fl mice gained more weight, had increased gonadal fat mass, increased meal number in the dark phase, and increased total food intake compared with wild-type controls. Resting energy expenditure was unaffected. The decrease in food intake produced by intraperitoneal injection of CCK (3 μg/kg body wt) was attenuated in female Nav1.8/LepRfl/fl mice compared with wild-type controls. Intraperitoneal injection of ghrelin (100 μg/kg body wt) increased food intake in Nav1.8/LepRfl/fl mice but not in wild-type controls. Ovarian steroidogenesis was suppressed, resulting in decreased plasma estradiol, which was accompanied by decreased expression of estrogen receptor-1 (Esr1) in VAN but not in the hypothalamic arcuate nucleus. These data suggest that the absence of leptin signaling in VAN is accompanied by disruption of estrogen signaling in female mice, leading to an obese phenotype possibly via altered control of feeding behavior.

NPY Deficiency Prevents Postmenopausal Adiposity by Augmenting Estradiol-Mediated Browning.

The orexigenic hormone neuropeptide Y (NPY) plays a pivotal role in the peripheral regulation of fat metabolism. However, the mechanisms underlying the effects of sex on NPY function have not been extensively analyzed. In this study, we examined the effects of NPY deficiency on fat metabolism in male and female mice. Body weight was slightly decreased, whereas white adipose tissue (WAT) mass was significantly decreased as the thermogenic program was upregulated in NPY-/- female mice compared with that in wild-type mice; these factors were not altered in response to NPY deficiency in male mice. Moreover, lack of NPY resulted in an increase in luteinizing hormone (LH) expression in the pituitary gland, with concomitant activation of the estradiol-mediated thermogenic program in inguinal WAT, and alleviated age-related modification of adiposity in female mice. Taken together, these data revealed a novel intracellular mechanism of NPY in the regulation of fat metabolism and highlighted the sexual dimorphism of NPY as a promising target for drug development to reduce postmenopausal adiposity.

GPR30 regulates diet-induced adiposity in female mice and adipogenesis in vitro.

Recent studies showed that GPR30, a seven-transmembrane G-protein-coupled receptor, is a novel estrogen receptor (ER) that mediates some biological events elicited by estrogen in several types of cancer cells. However, its physiological or pathological role in vivo is unclear. Here, we show that GPR30 knockout (GPRKO) female mice were protected from high-fat diet (HFD)-induced obesity, blood glucose intolerance, and insulin resistance. The decreased body weight gain in GPRKO female mice is due to the reduction in body fat mass. These effects occurred in the absence of significant changes in food intake, intestinal fat absorption, triglyceride metabolism, or energy expenditure. However, GPR30 had no significant metabolic effects in male mice fed the HFD and both sexes of mice fed a chow diet. Further, GPR30 expression levels in fat tissues of WT obese female mice were greatly increased, whereas ERα and β expression was not altered. Deletion of GPR30 reduced adipogenic differentiation of adipose tissue-derived stromal cells. Conversely, activation of GPR30 enhanced adipogenic differentiation of 3T3-L1 preadipocytes. These findings provide evidence for the first time that GPR30 promotes adipogenesis and therefore the development of obesity in female mice exposed to excess fat energy.

Interleukin-6 deletion in mice driven by aP2-Cre-ERT2 prevents against high-fat diet-induced gain weight and adiposity in female mice.

Interleukin-6 (IL-6) is a major cytokine controlling body weight and metabolism, but because many types of cells can synthesize and respond to IL-6 considerable uncertainty still exists about the mechanisms underlying IL-6 effects. Therefore, the aim of this study was to analyse the effects of tissue-specific deletion of IL-6 using a fatty acid binding protein (aP2) promoter-Cre inducible system (aP2-Cre-ERT2). Tissue-specific IL-6 KO mice (aP2-IL-6 KO mice) were produced upon tamoxifen administration and were fed a high-fat diet (HFD, 58.4% kcal from fat) or a control diet (18%) for 14 weeks. aP2-IL-6 KO female mice on a HFD gained less weight and adiposity than littermate wild-type mice, but these effects were not observed in males. Hypothalamic factors such as NPY and AgRP showed a pattern of expression consistent with this sex-specific phenotype. PGC-1α expression was increased in several tissues in aP2-IL-6 KO female mice, which is compatible with increased energy expenditure. Serum leptin, insulin, glucose, cholesterol and triglycerides levels were increased by HFD, and in females IL-6 deficiency reversed this effect in the case of insulin and cholesterol. HFD induced impaired responses to insulin and glucose tolerance tests, but no significant differences between genotypes were observed. The present results demonstrate that deletion of IL-6 driven by aP2-Cre regulates body weight, body fat and metabolism in a sex-specific fashion.

Selective Disruption of Dopamine D2 Receptors in Pituitary Lactotropes Increases Body Weight and Adiposity in Female Mice

Prolactin, a pleiotropic hormone secreted by lactotropes, has reproductive and metabolic functions. Chronically elevated prolactin levels increase food intake, but in some hyperprolactinemic states such as in the global dopamine D2 receptor (D2R) knockout mouse, food intake is not increased. Here, we conduct a cell-specific genetic dissection study using conditional mutant mice that selectively lack D2Rs from pituitary lactotropes (lacDrd2KO) to evaluate the role of elevated prolactin levels without any confounding effect of central D2Rs on motor and reward mechanisms related to food intake. LacDrd2KO female mice exhibited chronic hyperprolactinemia, pituitary hyperplasia, and a preserved GH axis. In addition, lacDrd2KO female but not male mice showed increased food intake by 3 months of age, and from 5 months onward their body weights were heavier. Marked increments in fat depots, adipocyte size, serum triglycerides, and nonesterified fatty acid levels and a decrease in lipolytic enzymes in adipose tissue were seen. Furthermore, lacDrd2KO female mice had glucose intolerance but a preserved response to insulin. In the hypothalamus, Npy mRNA expression was increased, and Pomc and Ppo mRNA levels were unaltered (in contrast to results in global D2R knockout mice). Thus, the orexigenic effect of prolactin and its action on hypothalamic Npy expression were fully evidenced, leading to increased food intake and adiposity. Our results highlight the metabolic role of prolactin and illustrate the value of studying cell-specific mutant mice to disentangle the pathophysiological mechanisms otherwise masked in null allele mutants or in animals treated with pervasive pharmacological agents.

The ZEB1 Transcription Factor Is a Novel Repressor of Adiposity in Female Mice

BackgroundFour genome-wide association studies mapped an “obesity” gene to human chromosome 10p11–12. As the zinc finger E-box binding homeobox 1 (ZEB1) transcription factor is encoded by the TCF8 gene located in that region, and as it influences the differentiation of various mesodermal lineages, we hypothesized that ZEB1 might also modulate adiposity. The goal of these studies was to test that hypothesis in mice.Methodology/Principal FindingsTo ascertain whether fat accumulation affects ZEB1 expression, female C57BL/6 mice were fed a regular chow diet (RCD) ad libitum or a 25% calorie-restricted diet from 2.5 to 18.3 months of age. ZEB1 mRNA levels in parametrial fat were six to ten times higher in the obese mice. To determine directly whether ZEB1 affects adiposity, wild type (WT) mice and mice heterozygous for TCF8 (TCF8+/−) were fed an RCD or a high-fat diet (HFD) (60% calories from fat). By two months of age on an HFD and three months on an RCD, TCF8+/− mice were heavier than WT controls, which was attributed by Echo MRI to increased fat mass (at three months on an HFD: 0.517±0.081 total fat/lean mass versus 0.313±0.036; at three months on an RCD: 0.175±0.013 versus 0.124±0.012). No differences were observed in food uptake or physical activity, suggesting that the genotypes differ in some aspect of their metabolic activity. ZEB1 expression also increases during adipogenesis in cell culture.Conclusion/SignificanceThese results show for the first time that the ZEB1 transcription factor regulates the accumulation of adipose tissue. Furthermore, they corroborate the genome-wide association studies that mapped an “obesity” gene at chromosome 10p11–12.