DPP4 deletion in adipose tissue improves hepatic insulin sensitivity in diet-induced obesity

Besides a therapeutic target for type 2 diabetes, dipeptidyl peptidase 4 (DPP4) is an adipokine potentially upregulated in human obesity. We aimed to explore the role of adipocyte-derived DPP4 in diet-induced obesity and insulin resistance with an adipose tissue-specific knockout (AT-DPP4-KO) mouse. Wild-type and AT-DPP4-KO mice were fed for 24 wk with a high fat diet (HFD) and characterized for body weight, glucose tolerance, insulin sensitivity by hyperinsulinemic-euglycemic clamp, and body composition and hepatic fat content. Image and molecular biology analysis of inflammation, as well as adipokine secretion, was performed in AT by immunohistochemistry, Western blot, real-time-PCR, and ELISA. Incretin levels were determined by Luminex kits. Under HFD, AT-DPP4-KO displayed markedly reduced circulating DPP4 concentrations, proving AT as a relevant source. Independently of glucose-stimulated incretin hormones, AT-DPP4-KO had improved glucose tolerance and hepatic insulin sensitivity. AT-DPP4-KO displayed smaller adipocytes and increased anti-inflammatory markers. IGF binding protein 3 (IGFBP3) levels were lower in AT and serum, whereas free IGF1 was increased. The absence of adipose DPP4 triggers beneficial AT remodeling with decreased production of IGFBP3 during HFD, likely contributing to the observed, improved hepatic insulin sensitivity.

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SMRT Regulates Metabolic Homeostasis and Adipose Tissue Macrophage Phenotypes in Tandem

Endocrinology ◽

10.1210/endocr/bqaa132 ◽

2020 ◽

Vol 161 (10) ◽

Author(s):

Jonathan H Kahn ◽

Anna Goddi ◽

Aishwarya Sharma ◽

Joshua Heiman ◽

Alanis Carmona ◽

...

Keyword(s):

Adipose Tissue ◽

Insulin Sensitivity ◽

Glucose Tolerance ◽

High Fat Diet ◽

Hormone Receptors ◽

Tissue Macrophage ◽

Secreted Factors ◽

Physiological Homeostasis

Abstract The Silencing Mediator of Retinoid and Thyroid Hormone Receptors (SMRT) is a nuclear corepressor, regulating the transcriptional activity of many transcription factors critical for metabolic processes. While the importance of the role of SMRT in the adipocyte has been well-established, our comprehensive understanding of its in vivo function in the context of homeostatic maintenance is limited due to contradictory phenotypes yielded by prior generalized knockout mouse models. Multiple such models agree that SMRT deficiency leads to increased adiposity, although the effects of SMRT loss on glucose tolerance and insulin sensitivity have been variable. We therefore generated an adipocyte-specific SMRT knockout (adSMRT-/-) mouse to more clearly define the metabolic contributions of SMRT. In doing so, we found that SMRT deletion in the adipocyte does not cause obesity—even when mice are challenged with a high-fat diet. This suggests that adiposity phenotypes of previously described models were due to effects of SMRT loss beyond the adipocyte. However, an adipocyte-specific SMRT deficiency still led to dramatic effects on systemic glucose tolerance and adipocyte insulin sensitivity, impairing both. This metabolically deleterious outcome was coupled with a surprising immune phenotype, wherein most genes differentially expressed in the adipose tissue of adSMRT-/- mice were upregulated in pro-inflammatory pathways. Flow cytometry and conditioned media experiments demonstrated that secreted factors from knockout adipose tissue strongly informed resident macrophages to develop a pro-inflammatory, MMe (metabolically activated) phenotype. Together, these studies suggest a novel role for SMRT as an integrator of metabolic and inflammatory signals to maintain physiological homeostasis.

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Adipose tissue inflammation contributes to short-term high-fat diet-induced hepatic insulin resistance

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00179.2013 ◽

2013 ◽

Vol 305 (3) ◽

pp. E388-E395 ◽

Cited By ~ 41

Author(s):

Michael S. F. Wiedemann ◽

Stephan Wueest ◽

Flurin Item ◽

Eugen J. Schoenle ◽

Daniel Konrad

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

Insulin Sensitivity ◽

Glucose Tolerance ◽

High Fat Diet ◽

Hepatic Insulin Resistance ◽

Adipose Tissue Inflammation ◽

High Fat ◽

Hepatic Insulin Sensitivity ◽

Tissue Inflammation

High-fat feeding for 3–4 days impairs glucose tolerance and hepatic insulin sensitivity. However, it remains unclear whether the evolving hepatic insulin resistance is due to acute lipid overload or the result of induced adipose tissue inflammation and consequent dysfunctional adipose tissue-liver cross-talk. In the present study, feeding C57Bl6/J mice a fat-enriched diet [high-fat diet (HFD)] for 4 days induced glucose intolerance, hepatic insulin resistance (as assessed by hyperinsulinemic euglycemic clamp studies), and hepatic steatosis as well as adipose tissue inflammation (i.e., TNFα expression) compared with standard chow-fed mice. Adipocyte-specific depletion of the antiapoptotic/anti-inflammatory factor Fas (CD95) attenuated adipose tissue inflammation and improved glucose tolerance as well as hepatic insulin sensitivity without altering the level of hepatic steatosis induced by HFD. In summary, our results identify adipose tissue inflammation and resulting dysfunctional adipose tissue-liver cross-talk as an early event in the development of HFD-induced hepatic insulin resistance.

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The Roles of Insulin Sensitivity, Insulin-Like Growth Factor I (IGF-I), and IGF-Binding Protein-1 and -3 in the Hyperandrogenism of African-American and Caribbean Hispanic Girls with Premature Adrenarche1

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.84.6.5722 ◽

1999 ◽

Vol 84 (6) ◽

pp. 2037-2042 ◽

Cited By ~ 1

Author(s):

Patricia Vuguin ◽

Barbara Linder ◽

Ron G. Rosenfeld ◽

Paul Saenger ◽

Joan DiMartino-Nardi

Keyword(s):

African American ◽

Insulin Sensitivity ◽

Growth Factor ◽

Binding Protein ◽

Insulin Like Growth Factor ◽

Factor I ◽

Igf I ◽

Igf Binding ◽

Growth Factor I ◽

Igf Binding Protein

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Improvement of obesity-associated disorders by a small-molecule drug targeting mitochondria of adipose tissue macrophages

Nature Communications ◽

10.1038/s41467-020-20315-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yawei Wang ◽

Binlin Tang ◽

Lei Long ◽

Peng Luo ◽

Wei Xiang ◽

...

Keyword(s):

Adipose Tissue ◽

Oxidative Phosphorylation ◽

Near Infrared ◽

Mitochondrial Metabolism ◽

Diet Induced Obesity ◽

Adipose Tissue Macrophages ◽

Inflammatory Activation ◽

Treatment Of Obesity ◽

Pharmaceutical Agents

AbstractPro-inflammatory activation of adipose tissue macrophages (ATMs) is causally linked to obesity and obesity-associated disorders. A number of studies have demonstrated the crucial role of mitochondrial metabolism in macrophage activation. However, there is a lack of pharmaceutical agents to target the mitochondrial metabolism of ATMs for the treatment of obesity-related diseases. Here, we characterize a near-infrared fluorophore (IR-61) that preferentially accumulates in the mitochondria of ATMs and has a therapeutic effect on diet-induced obesity as well as obesity-associated insulin resistance and fatty liver. IR-61 inhibits the classical activation of ATMs by increasing mitochondrial complex levels and oxidative phosphorylation via the ROS/Akt/Acly pathway. Taken together, our findings indicate that specific enhancement of ATMs oxidative phosphorylation improves chronic inflammation and obesity-related disorders. IR-61 might be an anti-inflammatory agent useful for the treatment of obesity-related diseases by targeting the mitochondria of ATMs.

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Partial Deficiency of Zfp217 Resists High-Fat Diet-Induced Obesity by Increasing Energy Metabolism in Mice

International Journal of Molecular Sciences ◽

10.3390/ijms22105390 ◽

2021 ◽

Vol 22 (10) ◽

pp. 5390

Author(s):

Qianhui Zeng ◽

Nannan Wang ◽

Yaru Zhang ◽

Yuxuan Yang ◽

Shuangshuang Li ◽

...

Keyword(s):

Adipose Tissue ◽

Weight Gain ◽

Insulin Sensitivity ◽

Energy Metabolism ◽

Glucose Tolerance ◽

High Fat Diet ◽

Chow Diet ◽

High Fat ◽

Glycolipid Metabolism ◽

Partial Deficiency

Obesity-induced adipose tissue dysfunction and disorders of glycolipid metabolism have become a worldwide research priority. Zfp217 plays a crucial role in adipogenesis of 3T3-L1 preadipocytes, but about its functions in animal models are not yet clear. To explore the role of Zfp217 in high-fat diet (HFD)-induced obese mice, global Zfp217 heterozygous knockout (Zfp217+/−) mice were constructed. Zfp217+/− mice and Zfp217+/+ mice fed a normal chow diet (NC) did not differ significantly in weight gain, percent body fat mass, glucose tolerance, or insulin sensitivity. When challenged with HFD, Zfp217+/− mice had less weight gain than Zfp217+/+ mice. Histological observations revealed that Zfp217+/− mice fed a high-fat diet had much smaller white adipocytes in inguinal white adipose tissue (iWAT). Zfp217+/− mice had improved metabolic profiles, including improved glucose tolerance, enhanced insulin sensitivity, and increased energy expenditure compared to the Zfp217+/+ mice under HFD. We found that adipogenesis-related genes were increased and metabolic thermogenesis-related genes were decreased in the iWAT of HFD-fed Zfp217+/+ mice compared to Zfp217+/− mice. In addition, adipogenesis was markedly reduced in mouse embryonic fibroblasts (MEFs) from Zfp217-deleted mice. Together, these data indicate that Zfp217 is a regulator of energy metabolism and it is likely to provide novel insight into treatment for obesity.

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The role of visceral adipose tissue on improvement in insulin sensitivity following Roux-en-Y gastric bypass: a study in Chinese diabetic patients with mild and central obesity

Gastroenterology Report ◽

10.1093/gastro/goy024 ◽

2018 ◽

Vol 6 (4) ◽

pp. 298-303 ◽

Cited By ~ 4

Author(s):

Lei Zhao ◽

Liyong Zhu ◽

Zhihong Su ◽

Weizheng Li ◽

Pengzhou Li ◽

...

Keyword(s):

Gastric Bypass ◽

Adipose Tissue ◽

Insulin Sensitivity ◽

Visceral Adipose Tissue ◽

Central Obesity ◽

Diabetic Patients ◽

Visceral Adipose

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Carbonyl Reductase 1 Overexpression in Adipose Amplifies Local Glucocorticoid Action and Impairs Glucose Tolerance in Lean Mice

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.1639 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A806-A806

Author(s):

Rachel Bell ◽

Elisa Villalobos ◽

Mark Nixon ◽

Allende Miguelez-Crespo ◽

Matthew Sharp ◽

...

Keyword(s):

Adipose Tissue ◽

Glucose Tolerance ◽

Fat Mass ◽

High Fat Diet ◽

Fasting Glucose ◽

High Fat ◽

Male And Female ◽

Over Expression ◽

Female Mice ◽

Diet Induced Obesity

Abstract Glucocorticoids play a critical role in metabolic homeostasis. Chronic or excessive activation of the glucocorticoid receptor (GR) in adipose tissue contributes to metabolic disorders such as glucose intolerance and insulin resistance. Steroid-metabolising enzymes in adipose, such as 11β-HSD1 or 5α-reductase, modulate the activation of GR by converting primary glucocorticoids into more or less potent ligands. Carbonyl reductase 1 (CBR1) is a novel regulator of glucocorticoid metabolism, converting corticosterone/cortisol to 20β-dihydrocorticosterone/cortisol (20β-DHB/F); a metabolite which retains GR activity. CBR1 is abundant in adipose tissue and increased in obese adipose of mice and humans1 and increased Cbr1 expression is associated with increased fasting glucose1. We hypothesised that increased Cbr1/20β-DHB in obese adipose contributes to excessive GR activation and worsens glucose tolerance. We generated a novel murine model of adipose-specific Cbr1 over-expression (R26-Cbr1Adpq) by crossing conditional knock-in mice with Adiponectin-Cre mice. CBR1 protein and activity were doubled in subcutaneous adipose tissue of male and female R26-Cbr1Adpq mice compared with floxed controls; corresponding to a two-fold increase 20β-DHB (1.6 vs. 4.2ng/g adipose; P=0.0003; n=5-7/group). There were no differences in plasma 20β-DHB or corticosterone. Bodyweight, lean or fat mass, did not differ between male or female R26-Cbr1Adpq mice and floxed controls. Lean male R26-Cbr1Adpq mice had higher fasting glucose (9.5±0.3 vs. 8.4±0.3mmol/L; P=0.04) and worsened glucose tolerance (AUC 1819±66 vs. 1392±14; P=0.03). Female R26-Cbr1Adpq mice also had a worsened glucose tolerance but fasting glucose was not altered with genotype. There were no differences in fasting insulin or non-esterified fatty acid between genotypes in either sex. Expression of GR-induced genes Pnpla2, Gilz and Per1, were increased in adipose of R26-Cbr1Adpq mice. Following high-fat diet induced obesity, no differences in bodyweight, lean or fat mass, with genotype were observed in male and female mice, and genotype differences in fasting glucose and glucose tolerance were abolished. In conclusion, adipose-specific over-expression of Cbr1 in lean male and female mice led to increased levels of 20β-DHB in adipose but not plasma, and both sexes having worsened glucose tolerance. The influence of adipose CBR1/20β-DHB on glucose tolerance was not associated with altered fat mass or bodyweight and was attenuated by high-fat diet-induced obesity. These metabolic consequences of Cbr1 manipulation require careful consideration given the wide variation in CBR1 expression in the human population, the presence of inhibitors and enhancers in many foodstuffs and the proposed use of inhibitors as an adjunct for cancer treatment regimens. Reference: Morgan et al., Scientific Reports. 2017; 7.

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Short-term strength training reduces gluconeogenesis and NAFLD in obese mice

Journal of Endocrinology ◽

10.1530/joe-18-0567 ◽

2019 ◽

Vol 241 (1) ◽

pp. 59-70 ◽

Cited By ~ 8

Author(s):

Rodrigo Martins Pereira ◽

Kellen Cristina da Cruz Rodrigues ◽

Chadi Pellegrini Anaruma ◽

Marcella Ramos Sant’Ana ◽

Thaís Dantis Pereira de Campos ◽

...

Keyword(s):

Weight Loss ◽

Insulin Sensitivity ◽

Strength Training ◽

Term Strength ◽

Obese Mice ◽

Short Term ◽

Fat Accumulation ◽

Hepatic Insulin Sensitivity ◽

Short Term Strength ◽

Hepatic Fat

Non-alcoholic fatty liver disease (NAFLD) has a positive correlation with obesity, insulin resistance and type 2 diabetes mellitus (T2D). The aerobic training is an important tool in combating NAFLD. However, no studies have demonstrated the molecular effects of short-term strength training on the accumulation of hepatic fat in obese mice. This study aimed to investigate the effects of short-term strength training on the mechanisms of oxidation and lipid synthesis in the liver of obese mice. The short duration protocol was used to avoid changing the amount of adipose tissue. Swiss mice were separated into three groups: lean control (CTL), sedentary obese (OB) and strength training obese (STO). The obese groups were fed a high-fat diet (HFD) and the STO group performed the strength training protocol 1 session/day for 15 days. The short-term strength training reduced hepatic fat accumulation, increasing hepatic insulin sensitivity and controlling hepatic glucose production. The obese animals increased the mRNA of lipogenic genes Fasn and Scd1 and reduced the oxidative genes Cpt1a and Ppara. On the other hand, the STO group presented the opposite results. Finally, the obese animals presented higher levels of lipogenic proteins (ACC and FAS) and proinflammatory cytokines (TNF-α and IL-1β), but the short-term strength training was efficient in reducing this condition, regardless of body weight loss. In conclusion, there was a reduction of obesity-related hepatic lipogenesis and inflammation after short-term strength training, independent of weight loss, leading to improvements in hepatic insulin sensitivity and glycemic homeostasis in obese mice. Key points: (1) Short-term strength training (STST) reduced fat accumulation and inflammation in the liver; (2) Hepatic insulin sensitivity and HPG control were increased with STST; (3) The content and activity of ACC and content of FAS were reduced with STST; (4) STST improved hepatic fat accumulation and glycemic homeostasis; (5) STST effects were observed independently of body weight change.

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