Regulation of Glucose Insulinotropic Peptide and Intestinal Glucose Transporters in the Diet-Induced Obese Mouse.

Our recent studies have shown that glucose-dependent insulinotropic polypeptide (GIP), but not glucagon-like peptide 1 (GLP-1), augments Na-glucose transporter 1- (SGLT1-) mediated glucose absorption in mouse jejunum. Na-dependent glucose absorption sharply rose and peaked in 3 months of high-fat (i.e., obese) compared to normal (i.e., normal weight) diet fed animals. Previous studies have shown that GIP-augmented SGLT1 and PEPT1 (peptide transporter 1) are regulated by protein kinase A (PKA) signaling in mouse jejunum. Additional studies have indicated that cAMP and PI3 kinase signaling augment PEPT1 through EPAC and AKT activation pathways, respectively, through increased apical PEPT1 trafficking in intestinal epithelial cells. However, little is known about how the signaling glucose transport paradigm is altered over a long period. Early on, increased glucose absorption occurs through SGLT1, but as the obesity and diabetes progress, there is a dramatic shift towards a Na-independent mechanism. Surprisingly, at the peak of glucose absorption during the fifth month of the progression of obesity, the SGLT1 activity was severely depressed, while a Na-independent glucose absorptive process begins to appear. Since glucose transporter 2 (GLUT2) is expressed on the apical membrane of the small intestine in obese patients and animal models of obesity, it was hypothesized to be the new more efficient route. Western blot analyses and biotinylation of the apical membrane revealed that the GIP expression increases in the obese animals and its trafficking to the apical membrane increases with the GIP treatment.

A propolis-derived small molecule ameliorates metabolic syndrome in obese mice by targeting the CREB/CRTC2 transcriptional complex.

The molecular targets and mechanisms of propolis ameliorating metabolic syndrome are not fully understood. Here, we report that Brazilian green propolis reduces fasting blood glucose levels in obese mice by disrupting the formation of CREB/CRTC2 transcriptional complex, a key regulator of hepatic gluconeogenesis. Using a mammalian two-hybrid system based on CREB-CRTC2, we identify artepillin C (APC) from propolis as an inhibitor of CREB-CRTC2 interaction. Without apparent toxicity, APC protects mice from high fat diet-induced obesity, decreases fasting glucose levels, enhances insulin sensitivity and reduces lipid levels in the serum and liver by suppressing CREB/CRTC2-mediated both gluconeogenic and SREBP transcriptions. To develop more potential drugs from APC, we designed and found a novel compound, A57 that exhibits higher inhibitory activity on CREB-CRTC2 association and better capability of improving insulin sensitivity in obese animals, as compared with APC. In this work, our results indicate that CREB/CRTC2 is a suitable target for developing anti-metabolic syndrome drugs.

Probiotics Stimulate Bone Formation in Obese Mice via Histone Methylations.

Rationale: Manipulation of the gut microbiome can prevent pathologic bone loss. However, the effects of probiotics on mitochondrial epigenetic remodeling and skeletal homeostasis in the high-fat diet (HFD)-linked obesity remains to be explored. Here, we examined the impact of probiotics supplementation on mitochondrial biogenesis and bone homeostasis through the histone methylation mechanism in HFD fed obese mice. Methods: 16S rRNA gene sequencing was performed to study the microbiota composition in the gut and microbial dysbiosis in obese mouse model. High resolution (microPET/CT) imaging was performed to demonstrate the obese associated colonic inflammation. Obese-associated upregulation of target miRNA in osteoblast was investigated using a microRNA qPCR array. Osteoblastic mitochondrial mass was evaluated using confocal imaging. Overexpression of mitochondrial transcription factor (Tfam) was used to investigate the glycolysis and mitochondrial bioenergetic metabolism using Tfam-transgenic (Tg) mice fed on HFD. The bone formation and mechanical strength was evaluated by microCT analysis and three-point bending analysis. Results: High-resolution imaging (µ-CT) and mechanical testing revealed that probiotics induced a significant increase of trabecular bone volume and bone mechanical strength respectively in obese mice. Probiotics or Indole-3-propionic acid (IPA) treatment directly to obese mice, prevents gut inflammation, and improved osteoblast mineralization. Mechanistically, probiotics treatment increases mitochondrial transcription factor A (Tfam) expression in osteoblasts by promoting Kdm6b/Jmjd3 histone demethylase, which inhibits H3K27me3 epigenetic methylation at the Tfam promoter. Furthermore, Tfam-transgenic (Tg) mice, fed with HFD, did not experience obesity-linked reduction of glucose uptake, mitochondrial biogenesis and mineralization in osteoblasts. Conclusions: These results suggest that the probiotics mediated changes in the gut microbiome and its derived metabolite, IPA are potentially be a novel agent for regulating bone anabolism via the gut-bone axis.

Hypothalamic long noncoding RNA AK044061 is involved in the development of dietary obesity in mice.

BACKGROUND: Long noncoding RNAs (lncRNAs) have been implicated in various important biological processes, however, its role in energy balance and obesity remains largely unknown. METHODS: Differentially expressed lncRNAs in the hypothalamus of diet-induced obesity (DIO) mice versus chow-fed mice were identified by RNA sequencing. Lentivirus-mediated overexpression and knockdown of a novel lncRNA, AK044061, were used to assess its role in energy balance and the development of DIO. RNA immunoprecipitation (RIP) and pull down assays were carried out to analyze the interaction between lncRNA AK044061 and RelA, an NF-κB subunit. RESULTS: LncRNA AK044061 was upregulated in the hypothalamus of DIO mice. Acute intracerebroventricular (i.c.v.) infusion of glucose reduced the expression of lncRNA AK044061, whereas an overnight of fasting enhanced its expression. RNA in situ hybridization data showed that AK044061 was expressed in the neurons of the arcuate nucleus (ARC). Lentivirus-mediated overexpression of AK044061 in ARC cells, or in the neurons of the ARC nucleus led to an obesity-like phenotype and related metabolic disorders. Furthermore, knockdown of lncRNA AK044061 in Agouti-related peptide (AgRP)-expressing neurons mitigated DIO and its related metabolic dysregulations. In mechanism, we showed that lncRNA AK044061 was associated with RelA and could enhance the NF-κB reporter activity. The effect of lncRNA AK044061 on energy balance is mediated by NF-κB. CONCLUSIONS: Our findings suggest that excessive lncRNA AK044061 in the ARC nucleus leads to energy imbalance and obesity. LncRNA AK044061 expressed in the AgRP neurons is important in the development of dietary obesity in mice.

Exercise Counterbalances Rho/ROCK2 Signaling Impairment in the Skeletal Muscle and Ameliorates Insulin Sensitivity in Obese Mice.

Physical exercise is considered a fundamental strategy in improving insulin sensitivity and glucose uptake in skeletal muscle. However, the molecular mechanisms underlying this regulation, primarily on skeletal muscle glucose uptake, are not fully understood. Recent evidence has shown that Rho-kinase (ROCK) isoforms play a pivotal role in regulating skeletal muscle glucose uptake and systemic glucose homeostasis. The current study evaluated the effect of physical exercise on ROCK2 signaling in skeletal muscle of insulin-resistant obese animals. Physiological (ITT) and molecular analysis (immunoblotting, and RT-qPCR) were performed. The contents of RhoA and ROCK2 protein were decreased in skeletal muscle of obese mice compared to control mice but were restored to normal levels in response to physical exercise. The exercised animals also showed higher phosphorylation of insulin receptor substrate 1 (IRS1 Serine 632/635) and protein kinase B (Akt) in the skeletal muscle. However, phosphatase and tensin homolog (PTEN) and protein-tyrosine phosphatase-1B (PTP-1B), both inhibitory regulators for insulin action, were increased in obesity but decreased after exercise. The impact of ROCK2 action on muscle insulin signaling is further underscored by the fact that impaired IRS1 and Akt phosphorylation caused by palmitate in C2C12 myotubes was entirely restored by ROCK2 overexpression. These results suggest that the exercise-induced upregulation of RhoA-ROCK2 signaling in skeletal muscle is associated with increased systemic insulin sensitivity in obese mice and further implicate that muscle ROCK2 could be a potential target for treating obesity-linked metabolic disorders.

Deficient Leptin Cellular Signaling Plays a Key Role in Brain Ultrastructural Remodeling in Obesity and Type 2 Diabetes Mellitus.

The triad of obesity, metabolic syndrome (MetS), Type 2 diabetes mellitus (T2DM) and advancing age are currently global societal problems that are expected to grow over the coming decades. This triad is associated with multiple end-organ complications of diabetic vasculopathy (maco-microvessel disease), neuropathy, retinopathy, nephropathy, cardiomyopathy, cognopathy encephalopathy and/or late-onset Alzheimer's disease. Further, obesity, MetS, T2DM and their complications are associated with economical and individual family burdens. This review with original data focuses on the white adipose tissue-derived adipokine/hormone leptin and how its deficient signaling is associated with brain remodeling in hyperphagic, obese, or hyperglycemic female mice. Specifically, the ultrastructural remodeling of the capillary neurovascular unit, brain endothelial cells (BECs) and their endothelial glycocalyx (ecGCx), the blood-brain barrier (BBB), the ventricular ependymal cells, choroid plexus, blood-cerebrospinal fluid barrier (BCSFB), and tanycytes are examined in female mice with impaired leptin signaling from either dysfunction of the leptin receptor (DIO and db/db models) or the novel leptin deficiency (BTBR ob/ob model).

Holdemanella biformis improves glucose tolerance and regulates GLP-1 signaling in obese mice.

Impaired glucose homeostasis in obesity is mitigated by enhancing the glucoregulatory actions of glucagon-like peptide 1 (GLP-1), and thus, strategies that improve GLP-1 sensitivity and secretion have therapeutic potential for the treatment of type 2 diabetes. This study shows that Holdemanella biformis, isolated from the feces of a metabolically healthy volunteer, ameliorates hyperglycemia, improves oral glucose tolerance and restores gluconeogenesis and insulin signaling in the liver of obese mice. These effects were associated with the ability of H. biformis to restore GLP-1 levels, enhancing GLP-1 neural signaling in the proximal and distal small intestine and GLP-1 sensitivity of vagal sensory neurons, and to modify the cecal abundance of unsaturated fatty acids and the bacterial species associated with metabolic health. Our findings overall suggest the potential use of H biformis in the management of type 2 diabetes in obesity to optimize the sensitivity and function of the GLP-1 system, through direct and indirect mechanisms.

Feeding-induced hepatokine, Manf, ameliorates diet-induced obesity by promoting adipose browning via p38 MAPK pathway.

Activating beige adipocytes in white adipose tissue (WAT) to increase energy expenditure is a promising strategy to combat obesity. We identified that mesencephalic astrocyte-derived neurotrophic factor (Manf) is a feeding-induced hepatokine. Liver-specific Manf overexpression protected mice against high-fat diet-induced obesity and promoted browning of inguinal subcutaneous WAT (iWAT). Manf overexpression in liver was also associated with decreased adipose inflammation and improved insulin sensitivity and hepatic steatosis. Mechanistically, Manf could directly promote browning of white adipocytes via the p38 MAPK pathway. Blockade of p38 MAPK abolished Manf-induced browning. Consistently, liver-specific Manf knockout mice showed impaired iWAT browning and exacerbated diet-induced obesity, insulin resistance, and hepatic steatosis. Recombinant Manf reduced obesity and improved insulin resistance in both diet-induced and genetic obese mouse models. Finally, we showed that circulating Manf level was positively correlated with BMI in humans. This study reveals the crucial role of Manf in regulating thermogenesis in adipose tissue, representing a potential therapeutic target for obesity and related metabolic disorders.

Plasma metabolomics analysis of the effects of drinking soda water on hyperglycemia mice using ultrahigh-pressure liquid chromatography-quadrupole-time of flight-mass spectrometry.

The aim of this study was to evaluate the effects of a natural soda water [Shi Han Quan (SHQ)] on hyperglycemia and plasma metabolic profiling and explore the mechanism using metabolomics techniques. Kun-Ming mice weighing 26 ± 2 g were used for the hyperglycemia animal model with alloxan and divided into control, hyperglycemia (HG), and HG + SHQ soda water (SHQ) groups. The experiment lasted for 30 days. The plasma metabolomic profiling of mice was determined using ultrahigh-pressure liquid chromatography-quadrupole-time of flight-mass spectrometry. After the mice drank SHQ soda water, the levels of insulin and blood glucose were significantly lower in the SHQ group compared with the control group, and the level of insulin sensitivity [insulin sensitivity index (ISI)] was significantly higher in the SHQ group compared with the HG group. The mice in the different groups after SHQ intervention could be separated into distinct clusters, and nine major plasma metabolites with significant differences between groups were found closely associated with blood glucose and ISI. The metabolic pathway analysis of these metabolites involved abnormal fatty acid oxidation and phospholipid, acylcarnitine, and corticoid metabolism. The results suggested the metabolic changes and possible mechanism of SHQ improving the alloxan-induced HG, and the findings provided insights into the prevention and control of HG and diabetes.

BMPER is upregulated in obesity and seems to have a role in pericardial adipose stem cells.

Pericardial adipose tissue (PAT), a visceral fat depot enveloping the heart, is an active endocrine organ and a source of free fatty acids and inflammatory cytokines. As in other fat adult tissues, PAT contains a population of adipose stem cells; however, whether these cells and/or their environment play a role in physiopathology is unknown. We analyzed several stem cell-related properties of pericardial adipose stem cells (PSCs) isolated from obese and ex-obese mice. We also performed RNA-sequencing to profile the transcriptional landscape of PSCs isolated from the different diet regimens. Finally, we tested whether these alterations impacted on the properties of cardiac mesoangioblasts isolated from the same mice. We found functional differences between PSCs depending on their source: specifically, PSCs from obese PSC (oPSC) and ex-obese PSC (dPSC) mice showed alterations in apoptosis and migratory capacity when compared with lean, control PSCs, with increased apoptosis in oPSCs and blunted migratory capacity in oPSCs and dPSCs. This was accompanied by different gene expression profiles across the cell types, where we identified some genes altered in obese conditions, such as BMP endothelial cell precursor-derived regulator (BMPER), an important regulator of BMP-related signaling pathways for endothelial cell function. The importance of BMPER in PSCs was confirmed by loss- and gain-of-function studies. Finally, we found an altered production of BMPER and some important chemokines in cardiac mesoangioblasts in obese conditions. Our findings point to BMPER as a potential new regulator of PSC function and suggest that its dysregulation could be associated with obesity and may impact on cardiac cells.

Endothelial ADAM17 Expression in the Progression of Kidney Injury in an Obese Mouse Model of Pre-Diabetes.

Disintegrin and metalloproteinase domain 17 (ADAM17) activates inflammatory and fibrotic processes through the shedding of various molecules such as Tumor Necrosis Factor-α (TNF-α) or Transforming Growht Factor-α (TGF-α). There is a well-recognised link between TNF-α, obesity, inflammation, and diabetes. In physiological situations, ADAM17 is expressed mainly in the distal tubular cell while, in renal damage, its expression increases throughout the kidney including the endothelium. The aim of this study was to characterize, for the first time, an experimental mouse model fed a high-fat diet (HFD) with a specific deletion of Adam17 in endothelial cells and to analyse the effects on different renal structures. Endothelial Adam17 knockout male mice and their controls were fed a high-fat diet, to induce obesity, or standard rodent chow, for 22 weeks. Glucose tolerance, urinary albumin-to-creatinine ratio, renal histology, macrophage infiltration, and galectin-3 levels were evaluated. Results showed that obese mice presented higher blood glucose levels, dysregulated glucose homeostasis, and higher body weight compared to control mice. In addition, obese wild-type mice presented an increased albumin-to-creatinine ratio; greater glomerular size and mesangial matrix expansion; and tubular fibrosis with increased galectin-3 expression. Adam17 deletion decreased the albumin-to-creatinine ratio, glomerular mesangial index, and tubular galectin-3 expression. Moreover, macrophage infiltration in the glomeruli of obese Adam17 knockout mice was reduced as compared to obese wild-type mice. In conclusion, the expression of ADAM17 in endothelial cells impacted renal inflammation, modulating the renal function and histology in an obese pre-diabetic mouse model.

Resistin is co-secreted with adiponectin in white mouse adipocytes.

In the current work we have investigated the cellular and molecular regulation of resistin secretion in cultured and primary mouse adipocytes. Resistin is an adipose tissue hormone proposed to contribute to metabolic disease. In rodents, resistin is secreted from white adipocytes whereas it is in humans synthesised and released from other cell types within white adipose tissue. The metabolic importance of resistin has been studied in both mouse and man, but the regulation of its release remains poorly investigated. Here we define that, in mouse adipocytes, resistin secretion is triggered by an intracellular elevation of cAMP and/or Ca2+. Resistin release is stimulated via activation of beta 3 adrenergic receptors (ß3ARs) and the downstream signalling protein exchange protein activated by cAMP (Epac). The secretion of resistin is markedly abrogated in adipocytes isolated from obese and diabetic mice. Immunocytochemical staining demonstrates a significant overlap between signals for resistin and the adipocyte hormone adiponectin. Our data propose that resistin and adiponectin are contained within the same vesicles in mouse adipocytes and that the two hormones are co-secreted in response to the same exocytosis-triggering signals.

An Ethanolic Extract of Artemisia dracunculus L. Enhances the Metabolic Benefits of Exercise in Diet-induced Obese Mice.

PURPOSE: The purpose of this study was to determine the effect of an ethanolic extract of Artemisia dracunculus L. (5011) combined with exercise on in vivo glucose and fat metabolism in diet-induced obese male mice. METHODS: After 8 wk of high-fat diet (HFD) feeding, 52 mice were randomly allocated to a voluntary wheel running group (HFD Ex), a 5011 + HFD sedentary group (5011 Sed), a 5011 + HFD Ex (5011 Ex), or an HFD sedentary group (HFD Sed) for 4 wk. Real-time energy expenditure and substrate utilization were measured by indirect calorimetry. A stable isotope glucose tolerance test was performed before and after the 4-wk wheel running period to determine changes in endogenous glucose production and glucose disposal. We also performed an analysis of genes and proteins associated with the early response to exercise and exercise adaptations in skeletal muscle and liver. RESULTS: When compared with HFD Ex mice, 5011 Ex mice had increased fat oxidation during speed- and distance-matched wheel running bouts. Both HFD Ex and 5011 Ex mice had reduced endogenous glucose during the glucose tolerance test, whereas only the 5011 Sed and the 5011 Ex mice had improved glucose disposal after the 4-wk experimental period when compared with HFD Sed and HFD Ex mice. 5011 Ex mice had increased Pgc1-α and Tfam expression in skeletal muscle when compared with HFD Ex mice, whereas Pdk4 expression was reduced in the liver of HFD Ex and 5011 Ex mice. CONCLUSIONS: Our study demonstrates that 5011, an ethanolic extract of A. dracunculus L., with a history of medicinal use, enhances the metabolic benefits of exercise to improve in vivo fat and glucose metabolism.

Oxygenated Water Inhibits Adipogenesis and Attenuates Hepatic Steatosis in High-Fat Diet-Induced Obese Mice.

The expansion of adipose tissue mass is the primary characteristic of the process of becoming obesity, which causes chronic adipose inflammation and is closely associated with type 2 diabetes mellitus (T2DM). Adipocyte hypertrophy restricts oxygen availability, leading to microenvironmental hypoxia and adipose dysfunction. This study aimed at investigating the effects of oxygenated water (OW) on adipocyte differentiation (adipogenesis) and the metabolic function of mature adipocytes. The effects of OW on adipogenesis and the metabolic function of mature adipocytes were examined. Meanwhile, the in vivo metabolic effects of long-term OW consumption on diet-induced obesity (DIO) mice were investigated. OW inhibited adipogenesis and lipid accumulation through down-regulating critical adipogenic transcription factors and lipogenic enzymes. While body weight, blood and adipose parameters were not significantly improved by long-term OW consumption, transient circulatory triglyceride-lowering and glucose tolerance-improving effects were identified. Notably, hepatic lipid contents were significantly reduced, indicating that the DIO-induced hepatic steatosis was attenuated, despite no improvements in fibrosis and lipid contents in adipose tissue being observed in the OW-drinking DIO mice. The study provides evidence regarding OW's effects on adipogenesis and mature adipocytes, and the corresponding molecular mechanisms. OW exhibits transient triglyceride-lowering and glucose tolerance-improving activity as well as hepatic steatosis-attenuating functions.

Lipocalin-2 counteracts metabolic dysregulation in obesity and diabetes.

Regulation of food intake is a recently identified endocrine function of bone that is mediated by Lipocalin-2 (LCN2). Osteoblast-secreted LCN2 suppresses appetite and decreases fat mass while improving glucose metabolism. We now show that serum LCN2 levels correlate with insulin levels and ß-cell function, indices of healthy glucose metabolism, in obese mice and obese, prediabetic women. However, LCN2 serum levels also correlate with body mass index and insulin resistance in the same individuals and are increased in obese mice. To dissect this apparent discrepancy, we modulated LCN2 levels in mice. Silencing Lcn2 expression worsens metabolic dysfunction in genetic and diet-induced obese mice. Conversely, increasing circulating LCN2 levels improves metabolic parameters and promotes ß-cell function in mouse models of ß-cell failure acting as a growth factor necessary for ß-cell adaptation to higher metabolic load. These results indicate that LCN2 up-regulation is a protective mechanism to counteract obesity-induced glucose intolerance by decreasing food intake and promoting adaptive ß-cell proliferation.

Intermittent Fasting and High-Intensity Exercise Elicit Sexual-Dimorphic and Tissue-Specific Adaptations in Diet-Induced Obese Mice.

: The molecular adaptations that underpin body composition changes and health benefits of intermittent fasting (IF) and high-intensity interval training (HIIT) are unclear. The present study investigated these adaptations within the hypothalamus, white adipose and skeletal muscle tissue following 12 weeks of IF and/or HIIT in diet-induced obese mice. Mice (C57BL/6, 8-week-old, males/females) were fed high-fat (59%) and sugar (30%) water (HF/S) for 12 weeks followed by an additional 12 weeks of HF/S plus either IF, HIIT, combination (IF+HIIT) or HF/S only control (CON). Tissues were harvested at 12 and 24 weeks and analysed for various molecular markers. Hypothalamic NPY expression was significantly lower following IF+HIIT compared to CON in females. In adipose tissue, leptin expression was significantly lower following IF and IF+HIIT compared to CON in males and females. Males demonstrated increased markers of fat oxidation (HADH, FABP4) following IF+HIIT, whereas females demonstrated reduced markers of adipocyte differentiation/storage (CIDEC and FOXO1) following IF and/or IF+HIIT. In muscle, SIRT1, UCP3, PGC1α, and AS160 expression was significantly lower following IF compared to CON in males and/or females. This investigation suggests that males and females undertaking IF and HIIT may prevent weight gain via different mechanisms within the same tissue.

Obesity reduces mammary epithelial cell TGFß1 activity through macrophage-mediated extracellular matrix remodeling.

Obesity is a risk factor for breast cancer in postmenopausal and high-risk premenopausal women. Changes within the obese breast microenvironment may increase breast cancer risk. Transforming growth factor beta-1 (TGFß1) is a major regulator of mammary epithelial stem/progenitor cells, and its activity is dysregulated under conditions of obesity. Using a high-fat diet model of obesity in mice and breast tissue from women, we observed that TGFß1 activity is reduced in breast epithelial cells in obesity. Breast ducts and lobules demonstrated increased decorin in the extracellular matrix (ECM) surrounding epithelial cells, and we observed that decorin and latent TGFß1 complexed together. Under conditions of obesity, macrophages expressed higher levels of decorin and were significantly increased in number surrounding breast epithelial cells. To investigate the relationship between macrophages and decorin expression, we treated obese mice with either IgG control or anti-F4/80 antibodies to deplete macrophages. Mice treated with anti-F4/80 antibodies demonstrated reduced decorin surrounding mammary ducts and enhanced TGFß1 activity within mammary epithelial cells. Given the role of TGFß1 as a tumor suppressor, reduced epithelial TGFß1 activity and enhanced TGFß1 within the ECM of obese mammary tissue may enhance breast cancer risk.

Inhibition of PU.1 ameliorates metabolic dysfunction and non-alcoholic steatohepatitis.

BACKGROUND & AIMS: Obesity is a well-established risk factor for type 2 diabetes (T2D) and non-alcoholic steatohepatitis (NASH), but the underlying mechanisms remain incompletely understood. Herein, we aimed to identify novel pathogenic factors (and possible therapeutic targets) underlying metabolic dysfunction in the liver. METHODS: We applied a tandem quantitative proteomics strategy to enrich and identify transcription factors (TFs) induced in the obese liver. We used flow cytometry of liver cells to analyze the source of the induced TFs. We employed conditional knockout mice, shRNA, and small-molecule inhibitors to test the metabolic consequences of the induction of identified TFs. Finally, we validated mouse data in patient liver biopsies. RESULTS: We identified PU.1/SPI1, the master hematopoietic regulator, as one of the most upregulated TFs in livers from diet-induced obese (DIO) and genetically obese (db/db) mice. Targeting PU.1 in the whole liver, but not hepatocytes alone, significantly improved glucose homeostasis and suppressed liver inflammation. Consistently, treatment with the PU.1 inhibitor DB1976 markedly reduced inflammation and improved glucose homeostasis and dyslipidemia in DIO mice, and strongly suppressed glucose intolerance, liver steatosis, inflammation, and fibrosis in a dietary NASH mouse model. Furthermore, hepatic PU.1 expression was positively correlated with insulin resistance and inflammation in liver biopsies from patients. CONCLUSIONS: These data suggest that the elevated hematopoietic factor PU.1 promotes liver metabolic dysfunction, and may be a useful therapeutic target for obesity, insulin resistance/T2D, and NASH. LAY SUMMARY: Expression of the immune regulator PU.1 is increased in livers of obese mice and people. Blocking PU.1 improved glucose homeostasis, and reduced liver steatosis, inflammation and fibrosis in mouse models of non-alcoholic steatohepatitis. Inhibition of PU.1 is thus a potential therapeutic strategy for treating obesity-associated liver dysfunction and metabolic diseases.

Exercise prevents the adverse effects of maternal obesity on placental vascularization and fetal growth.

KEY POINTS: Maternal exercise improves the metabolic health of maternal mice challenged with a high-fat diet. Exercise intervention of obese mothers prevents fetal overgrowth. Exercise intervention reverses impaired placental vascularization in obese mice. Maternal exercise activates placental AMP-activated protein kinase, which was inhibited as a result of maternal obesity. ABSTRACT: More than one-third of pregnant women in the USA are obese and maternal obesity (MO) negatively affects fetal development, which predisposes offspring to metabolic diseases. The placenta mediates nutrient delivery to fetuses and its function is impaired as a result of MO. Exercise ameliorates metabolic dysfunction resulting from obesity, although its effect on placental function of obese mothers has not been explored. In the present study, C57BL/6J female mice were randomly assigned into two groups fed either a control or a high-fat diet (HFD) and then the mice on each diet were further divided into two subgroups with/without exercise. In HFD-induced obese mice, daily treadmill exercise during pregnancy reduced body weight gain, lowered serum glucose and lipid concentration, and improved insulin sensitivity of maternal mice. Importantly, maternal exercise prevented fetal overgrowth (macrosomia) induced by MO. To further examine the preventive effects of exercise on fetal overgrowth, placental vascularization and nutrient transporters were analysed. Vascular density and the expression of vasculogenic factors were reduced as a result of MO but were recovered by maternal exercise. On the other hand, the contents of nutrient transporters were not substantially altered by MO or exercise, suggesting that the protective effects of exercise in MO-induced fetal overgrowth were primarily a result of the alteration of placental vascularization and improved maternal metabolism. Furthermore, exercise enhanced downstream insulin signalling and activated AMP-activated protein kinase in HFD placenta. In sum, maternal exercise prevented fetal overgrowth induced by MO, which was associated with improved maternal metabolism and placental vascularization in obese mothers with exercise.

Fluorescent blood-brain barrier tracing shows intact leptin transport in obese mice.

BACKGROUND/OBJECTIVES: Individuals carrying loss-of-function gene mutations for the adipocyte hormone leptin are morbidly obese, but respond favorably to replacement therapy. Recombinant leptin is however largely ineffective for the vast majority of obese individuals due to leptin resistance. One theory underlying leptin resistance is impaired leptin transport across the blood-brain-barrier (BBB). Here, we aim to gain new insights into the mechanisms of leptin BBB transport, and its role in leptin resistance. METHODS: We developed a novel tool for visualizing leptin transport using infrared fluorescently labeled leptin, combined with tissue clearing and light-sheet fluorescence microscopy. We corroborated these data using western blotting. RESULTS: Using 3D whole brain imaging, we display comparable leptin accumulation in circumventricular organs of lean and obese mice, predominantly in the choroid plexus (CP). Protein quantification revealed comparable leptin levels in microdissected mediobasal hypothalami (MBH) of lean and obese mice (p = 0.99). We further found increased leptin receptor expression in the CP (p = 0.025, p = 0.0002) and a trend toward elevated leptin protein levels in the MBH (p = 0.17, p = 0.078) of obese mice undergoing weight loss interventions by calorie restriction or exendin-4 treatment. CONCLUSIONS: Overall, our findings suggest a crucial role for the CP in controlling the transport of leptin into the cerebrospinal fluid and from there to target areas such as the MBH, potentially mediated via the leptin receptor. Similar leptin levels in circumventricular organs and the MBH of lean and obese mice further suggest intact leptin BBB transport in leptin resistant mice.