scholarly journals SMRT Regulates Metabolic Homeostasis and Adipose Tissue Macrophage Phenotypes in Tandem

Endocrinology ◽  
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.

CX3CL1–CX3CR1 signalling deficiency exacerbates obesity-induced inflammation and insulin resistance in male mice

Endocrinology ◽  
2021 ◽  
Author(s):  
Mayumi Nagashimada ◽  
Kazuki Sawamoto ◽  
Yinhua Ni ◽  
Hironori Kitade ◽  
Naoto Nagata ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Glucose Tolerance ◽  
High Fat Diet ◽  
Adipose Tissue Inflammation ◽  
Tissue Inflammation ◽  
Tissue Macrophage ◽  
Epididymal White Adipose Tissue

Abstract The CX3CL1–CX3CR1 system plays an important role in disease progression by regulating inflammation both positively and negatively. We reported previously that C-C chemokine receptor 5, as well as CCR2, promotes obesity-associated adipose tissue inflammation and insulin resistance. Here, we demonstrate that CX3CL1–CX3CR1 signalling is involved in adipose tissue inflammation and insulin resistance in obese mice, via adipose tissue macrophage recruitment and M1/M2 polarization. CX3CL1 expression was persistently decreased in the epididymal white adipose tissue (eWAT) of high-fat diet-induced obese (DIO) mice, despite increased expression of other chemokines. Interestingly, in Cx3cr1  −/− mice, glucose tolerance, insulin resistance, and hepatic steatosis induced by DIO or leptin deficiency were exacerbated. CX3CL1–CX3CR1 signalling deficiency resulted in reduced M2-polarized macrophage migration and an M1-dominant shift of macrophages within eWAT. Furthermore, transplantation of Cx3cr1  −/− bone marrow was sufficient to impair glucose tolerance, insulin sensitivity, and regulation of M1/M2 status. Moreover, CX3CL1 administration in vivo led to the attenuation of glucose intolerance and insulin resistance. Thus, therapy targeting the CX3CL1–CX3CR1 system may be beneficial in the treatment of type 2 diabetes by regulating M1/M2 macrophages.

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

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.

scholarly journals Adipocyte PU.1 knockout promotes insulin sensitivity in HFD-fed obese mice

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Denise E. Lackey ◽  
Felipe C. G. Reis ◽  
Roi Isaac ◽  
Rizaldy C. Zapata ◽  
Dalila El Ouarrat ◽  
...  
Keyword(s):  
Gene Expression ◽  
Insulin Resistance ◽  
Type 2 Diabetes ◽  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Target Genes ◽  
Obese Mice ◽  
Tissue Macrophage

Abstract Insulin resistance is a key feature of obesity and type 2 diabetes. PU.1 is a master transcription factor predominantly expressed in macrophages but after HFD feeding PU.1 expression is also significantly increased in adipocytes. We generated adipocyte specific PU.1 knockout mice using adiponectin cre to investigate the role of PU.1 in adipocyte biology, insulin and glucose homeostasis. In HFD-fed obese mice systemic glucose tolerance and insulin sensitivity were improved in PU.1 AKO mice and clamp studies indicated improvements in both adipose and liver insulin sensitivity. At the level of adipose tissue, macrophage infiltration and inflammation was decreased and glucose uptake was increased in PU.1 AKO mice compared with controls. While PU.1 deletion in adipocytes did not affect the gene expression of PPARg itself, we observed increased expression of PPARg target genes in eWAT from HFD fed PU.1 AKO mice compared with controls. Furthermore, we observed decreased phosphorylation at serine 273 in PU.1 AKO mice compared with fl/fl controls, indicating that PPARg is more active when PU.1 expression is reduced in adipocytes. Therefore, in obesity the increased expression of PU.1 in adipocytes modifies the adipocyte PPARg cistrome resulting in impaired glucose tolerance and insulin sensitivity.

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

2020 ◽  
Vol 318 (5) ◽  
pp. E590-E599 ◽  
Author(s):  
Tania Romacho ◽  
Henrike Sell ◽  
Ira Indrakusuma ◽  
Diana Roehrborn ◽  
Tamara R. Castañeda ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
Hepatic Insulin Sensitivity ◽  
Dipeptidyl Peptidase 4 ◽  
Diet Induced Obesity ◽  
Hepatic Fat ◽  
Igf Binding ◽  
Igf Binding Protein

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.

scholarly journals Oleacein Prevents High Fat Diet-Induced A Diposity and Ameliorates Some Biochemical Parameters of Insulin Sensitivity in Mice

Nutrients ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1829 ◽  
Author(s):  
Lepore ◽  
Maggisano ◽  
Bulotta ◽  
Mignogna ◽  
Arcidiacono ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Insulin Sensitivity ◽  
High Fat Diet ◽  
Fatty Acid Synthase ◽  
Glucose Transporter ◽  
Regulatory Element ◽  
Regulatory Elements ◽  
High Fat

Oleacein is one of the most abundant polyphenolic compounds of olive oil, which has been shown to play a protective role against several metabolic abnormalities, including dyslipidemia, insulin resistance, and glucose intolerance. Herein, we investigated the effects of oleacein on certain markers of adipogenesis and insulin-resistance in vitro, in 3T3-L1 adipocytes, and in vivo in high-fat diet (HFD)-fed mice. During the differentiation process of 3T3-L1 preadipocytes into adipocytes, oleacein strongly inhibited lipid accumulation, and decreased protein levels of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid synthase (FAS), while increasing Adiponectin levels. In vivo, treatment with oleacein of C57BL/6JOlaHsd mice fed with HFD for 5 and 13 weeks prevented the increase in adipocyte size and reduced the inflammatory infiltration of macrophages and lymphocytes in adipose tissue. These effects were accompanied by changes in the expression of adipose tissue-specific regulatory elements such as PPARγ, FAS, sterol regulatory element-binding transcription factor-1 (SREBP-1), and Adiponectin, while the expression of insulin-sensitive muscle/fat glucose transporter Glut-4 was restored in HFD-fed mice treated with oleacein. Collectively, our findings indicate that protection against HFD-induced adiposity by oleacein in mice is mediated by the modulation of regulators of adipogenesis. Protection against HFD-induced obesity is effective in improving peripheral insulin sensitivity.

scholarly journals Endothelial TFEB (Transcription Factor EB) Improves Glucose Tolerance via Upregulation of IRS (Insulin Receptor Substrate) 1 and IRS2

2020 ◽  
Author(s):  
Jinjian Sun ◽  
Haocheng Lu ◽  
Wenying Liang ◽  
Guizhen Zhao ◽  
Lu Ren ◽  
...  
Keyword(s):  
Glucose Tolerance ◽  
Transgenic Mice ◽  
High Fat Diet ◽  
Metabolic Diseases ◽  
Critical Role ◽  
Insulin Receptor Substrate ◽  
High Fat ◽  
Transcription Factor Eb

Objective: Vascular endothelial cells (ECs) play a critical role in maintaining vascular homeostasis. Aberrant EC metabolism leads to vascular dysfunction and metabolic diseases. TFEB (transcription factor EB), a master regulator of lysosome biogenesis and autophagy, has protective effects on vascular inflammation and atherosclerosis. However, the role of endothelial TFEB in metabolism remains to be explored. In this study, we sought to investigate the role of endothelial TFEB in glucose metabolism and underlying molecular mechanisms. Approach and Results: To determine whether endothelial TFEB is critical for glucose metabolism in vivo, we utilized EC-selective TFEB knockout and EC-selective TFEB transgenic mice fed a high-fat diet. EC-selective TFEB knockout mice exhibited significantly impaired glucose tolerance compared with control mice. Consistently, EC-selective TFEB transgenic mice showed improved glucose tolerance. In primary human ECs, small interfering RNA-mediated TFEB knockdown blunts Akt (AKT serine/threonine kinase) signaling. Adenovirus-mediated overexpression of TFEB consistently activates Akt and significantly increases glucose uptake in ECs. Mechanistically, TFEB upregulates IRS1 and IRS2 (insulin receptor substrate 1 and 2). TFEB increases IRS2 transcription measured by reporter gene and chromatin immunoprecipitation assays. Furthermore, we found that TFEB increases IRS1 protein via downregulation of microRNAs (miR-335, miR-495, and miR-548o). In vivo, Akt signaling in the skeletal muscle and adipose tissue was significantly impaired in EC-selective TFEB knockout mice and consistently improved in EC-selective TFEB transgenic mice on high-fat diet. Conclusions: Our data revealed a critical role of TFEB in endothelial metabolism and suggest that TFEB constitutes a potential molecular target for the treatment of vascular and metabolic diseases.

scholarly journals Inactivation of SPAK kinase reduces body weight gain in mice fed a high-fat diet by improving energy expenditure and insulin sensitivity

2018 ◽  
Vol 314 (1) ◽  
pp. E53-E65 ◽  
Author(s):  
Ivan Torre-Villalvazo ◽  
Luz Graciela Cervantes-Pérez ◽  
Lilia G. Noriega ◽  
Jose V. Jiménez ◽  
Norma Uribe ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Weight Gain ◽  
Insulin Sensitivity ◽  
Energy Expenditure ◽  
Glucose Tolerance ◽  
High Fat Diet ◽  
Whole Body ◽  
High Fat ◽  
The Metabolic Syndrome ◽  
Brown Adipose

The STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) controls the activity of the electroneutral cation-chloride cotransporters (SLC12 family) and thus physiological processes such as modulation of cell volume, intracellular chloride concentration [Cl−]i, and transepithelial salt transport. Modulation of SPAK kinase activity may have an impact on hypertension and obesity, as STK39, the gene encoding SPAK, has been suggested as a hypertension and obesity susceptibility gene. In fact, the absence of SPAK activity in mice in which the activating threonine in the T loop was substituted by alanine (SPAK-KI mice) is associated with decreased blood pressure; however its consequences in metabolism have not been explored. Here, we fed wild-type and homozygous SPAK-KI mice a high-fat diet for 17 wk to evaluate weight gain, circulating substrates and hormones, energy expenditure, glucose tolerance, and insulin sensitivity. SPAK-KI mice exhibit resistance to HFD-induced obesity and hepatic steatosis associated with increased energy expenditure, higher thermogenic activity in brown adipose tissue, increased mitochondrial activity in skeletal muscle, and reduced white adipose tissue hypertrophy mediated by augmented whole body insulin sensitivity and glucose tolerance. Our data reveal a previously unrecognized role for the SPAK kinase in the regulation of energy balance, thermogenesis, and insulin sensitivity, suggesting that this kinase could be a new drug target for the treatment of obesity and the metabolic syndrome.

Egg white hydrolysate enhances insulin sensitivity in high-fat diet-induced insulin-resistant rats via Akt activation

2019 ◽  
Vol 122 (1) ◽  
pp. 14-24 ◽  
Author(s):  
F. Jahandideh ◽  
S. C. de Campos Zani ◽  
M. Son ◽  
S. D. Proctor ◽  
S. T. Davidge ◽  
...  
Keyword(s):  
Insulin Sensitivity ◽  
Glucose Tolerance ◽  
High Fat Diet ◽  
Egg White ◽  
Oral Glucose ◽  
Protein Abundance ◽  
Oral Glucose Tolerance ◽  
High Fat ◽  
Insulin Resistant

AbstractAgents that block the renin–angiotensin system (RAS) improve glucoregulation in the metabolic syndrome disorder. We evaluated the effects of egg white hydrolysate (EWH), previously shown to modulate the protein abundance of RAS component in vivo, on glucose homeostasis in diet-induced insulin-resistant rats. Sprague–Dawley rats were fed a high-fat diet (HFD) for 6 weeks to induce insulin resistance. They were then randomly divided into four groups receiving HFD or HFD supplemented with different concentrations of EWH (1, 2 and 4 %) for another 6 weeks in the first trial. In the second trial, insulin-resistant rats were divided into two groups receiving only HFD or HFD+4 % EWH for 6 weeks. Glucose homeostasis was assessed by oral glucose tolerance and insulin tolerance tests. Insulin signalling and protein abundance of RAS components, gluconeogenesis enzymes and PPARγ were evaluated in muscle, fat and liver. Adipocyte morphology and inflammatory markers were evaluated. In vivo administration of EWH increased insulin sensitivity, improved oral glucose tolerance (P < 0·0001) and reduced systemic inflammation (P < 0·05). EWH potentiated insulin-induced Akt phosphorylation in muscle (P = 0·0341) and adipose tissue (P = 0·0276), but minimal differences in the protein abundance of tissue RAS components between the EWH and control groups were observed. EWH treatment also reduced adipocyte size (P = 0·0383) and increased PPARγ2 protein abundance (P = 0·0237). EWH treatment yielded positive effects on the inflammatory profile, glucose tolerance, insulin sensitivity and adipocyte differentiation in HFD-induced insulin resistance rats. The involvement of local RAS activity requires further investigation.

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