scholarly journals Seipin Deficiency as a Model of Severe Adipocyte Dysfunction: Lessons from Rodent Models and Teaching for Human Disease

2022 ◽  
Vol 23 (2) ◽  
pp. 740
Author(s):  
Jocelyne Magré ◽  
Xavier Prieur
Keyword(s):  
Adipose Tissue ◽  
Knockout Mice ◽  
Liver Steatosis ◽  
Large Body ◽  
Severe Form ◽  
Obesity Prevalence ◽  
Metabolic Complications ◽  
Adipose Tissue Expandability ◽  
New Strategies ◽  
Specific Deletion

Obesity prevalence is increasing worldwide, leading to cardiometabolic morbidities. Adipocyte dysfunction, impairing white adipose tissue (WAT) expandability and metabolic flexibility, is central in the development of obesity-related metabolic complications. Rare syndromes of lipodystrophy characterized by an extreme paucity of functional adipose tissue should be considered as primary adipocyte dysfunction diseases. Berardinelli-Seip congenital lipodystrophy (BSCL) is the most severe form with a near absence of WAT associated with cardiometabolic complications such as insulin resistance, liver steatosis, dyslipidemia, and cardiomyopathy. Twenty years ago, mutations in the BSCL2 gene have been identified as the cause of BSCL in human. BSCL2 encodes seipin, an endoplasmic reticulum (ER) anchored protein whose function was unknown back then. Studies of seipin knockout mice or rats demonstrated how seipin deficiency leads to severe lipodystrophy and to cardiometabolic complications. At the cellular levels, seipin is organized in multimers that are particularly enriched at ER/lipid droplet and ER/mitochondria contact sites. Seipin deficiency impairs both adipocyte differentiation and mature adipocyte maintenance. Experiments using adipose tissue transplantation in seipin knockout mice and tissue-specific deletion of seipin have provided a large body of evidence that liver steatosis, cardiomyopathy, and renal injury, classical diabetic complications, are all consequences of lipodystrophy. Rare adipocyte dysfunctions such as in BSCL are the key paradigm to unravel the pathways that control adipocyte homeostasis. The knowledge gathered through the study of these pathologies may bring new strategies to maintain and improve adipose tissue expandability.

scholarly journals Myeloid-specific deletion of thrombospondin 1 protects against inflammation and insulin resistance in long-term diet-induced obese male mice

2018 ◽  
Vol 315 (6) ◽  
pp. E1194-E1203 ◽  
Author(s):  
Hasiyet Memetimin ◽  
Dong Li ◽  
Kaiyuan Tan ◽  
Changcheng Zhou ◽  
Ying Liang ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Matricellular Protein ◽  
High Fat ◽  
Metabolic Complications ◽  
Diet Induced Obesity ◽  
Thrombospondin 1 ◽  
Specific Deletion

Thrombospondin 1 (TSP1) is a multifunctional matricellular protein. Recent studies demonstrate that TSP1 is highly expressed in adipose tissue (AT) and positively associated with AT inflammation and insulin resistance (IR). In this study, the contribution of different cellular sources of TSP1 to obesity-induced metabolic complications is determined by using mice with either adipocyte or myeloid/macrophage-specific deletion of TSP1 in a diet-induced obese model. The results demonstrated that neither adipocyte nor myeloid/macrophage-specific deletion of TSP1 affected the development of long-term high-fat diet-induced obesity. Adipocyte-specific deletion of TSP1 did not protect mice from obesity-induced inflammation and IR. On the contrary, obese mice with myeloid/macrophage loss of TSP1 had reduced macrophage accumulation in AT, which was accompanied with reduced inflammation and improved glucose tolerance and insulin sensitivity compared with obese control mice. Reduced macrophage-derived-TGF-β1 signaling and adipose tissue fibrosis were also observed in long-term high-fat-fed mice with myeloid/macrophage-specific TSP1 deletion. Moreover, in vitro experiments demonstrated an autocrine effect of TSP1-mediated TGF-β activation in macrophages in obesity. Collectively this study highlights the critical contribution of myeloid/macrophage-derived TSP1 to obesity-associated chronic inflammation and IR, which may serve as a new therapeutic target for metabolic disease.

GPAT3 deficiency alleviates insulin resistance and hepatic steatosis in a mouse model of severe congenital generalized lipodystrophy

2019 ◽  
Vol 29 (3) ◽  
pp. 432-443 ◽  
Author(s):  
Mingming Gao ◽  
Lin Liu ◽  
Xiaowei Wang ◽  
Hoi Yin Mak ◽  
George Liu ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Liver Steatosis ◽  
Subcutaneous Fat ◽  
Severe Form ◽  
Loss Of Function ◽  
Tissue Mass ◽  
Functional Link ◽  
Brown Adipose

Abstract Berardinelli-Seip congenital lipodystrophy type 2 (BSCL2) is the most severe form of human lipodystrophy and is caused by loss-of-function mutations in the BSCL2/seipin gene. Exactly how seipin may regulate adipogenesis remains unclear. A recent study in vitro suggested that seipin may function to inhibit the activity of glycerol-3-phosphate acyltransferases (GPATs), and increased GPAT activity may be responsible for the defective adipogenesis under seipin deficiency. Here we generated Seipin−/−Gpat3−/− mice, which had mild but significant recovery of white adipose tissue mass over Seipin−/− mice. The mass of brown adipose tissue (BAT) of the Seipin−/−Gpat3−/− mice was almost completely restored to normal level. Importantly, the Seipin−/−Gpat3−/− mice showed significant improvement in liver steatosis and insulin sensitivity over Seipin−/− mice, which is attributable to the increased BAT mass and to the enhanced browning of the subcutaneous fat of the Seipin−/−Gpat3−/− mice. Together, our results establish a functional link between seipin and GPAT3 in vivo and suggest that GPAT inhibitors may have beneficial effects on BSCL2 patients.

Adipose tissue expandability: the metabolic problems of obesity may arise from the inability to become more obese

2008 ◽  
Vol 36 (5) ◽  
pp. 935-940 ◽  
Author(s):  
Chong Yew Tan ◽  
Antonio Vidal-Puig
Keyword(s):  
Adipose Tissue ◽  
Metabolic Disturbances ◽  
Metabolic Complications ◽  
The Face ◽  
Prevalence Of Obesity ◽  
Caloric Excess ◽  
Adipose Tissue Expandability ◽  
Caloric Balance ◽  
Consequences Of Obesity

The prevalence of obesity is increasing and with it the prevalence of associated metabolic complications. Precisely how obesity results in metabolic disturbances remains unclear. In the face of persistent positive caloric balance, it has been postulated that the capacity of adipose tissue to safely store fat may be vital. This paper explores some of the evidence suggesting that the risk of developing metabolic disturbances is not related to how much fat an individual has, but how well their fat can expand to accommodate the caloric excess. If this is true, the metabolic consequences of obesity may arise from the inability to become more obese.

Inflammation and impaired adipogenesis in hypertrophic obesity in man

2009 ◽  
Vol 297 (5) ◽  
pp. E999-E1003 ◽  
Author(s):  
Birgit Gustafson ◽  
Silvia Gogg ◽  
Shahram Hedjazifar ◽  
Lachmi Jenndahl ◽  
Ann Hammarstedt ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Adipose Tissue ◽  
Subcutaneous Adipose Tissue ◽  
Molecular Mechanisms ◽  
Whole Body ◽  
Preadipocyte Differentiation ◽  
Metabolic Complications ◽  
Adipose Cell ◽  
Subcutaneous Adipose ◽  
Adipose Cell Size

Obesity is associated mainly with adipose cell enlargement in adult man (hypertrophic obesity), whereas the formation of new fat cells (hyperplastic obesity) predominates in the prepubertal age. Adipose cell size, independent of body mass index, is negatively correlated with whole body insulin sensitivity. Here, we review recent findings linking hypertrophic obesity with inflammation and a dysregulated adipose tissue, including local cellular insulin resistance with reduced IRS-1 and GLUT4 protein content. In addition, the number of preadipocytes in the abdominal subcutaneous adipose tissue capable of undergoing differentiation to adipose cells is reduced in hypertrophic obesity. This is likely to promote ectopic lipid accumulation, a well-known finding in these individuals and one that promotes insulin resistance and cardiometabolic risk. We also review recent results showing that TNFα, but not MCP-1, resistin, or IL-6, completely prevents normal adipogenesis in preadipocytes, activates Wnt signaling, and induces a macrophage-like phenotype in the preadipocytes. In fact, activated preadipocytes, rather than macrophages, may completely account for the increased release of chemokines and cytokines by the adipose tissue in obesity. Understanding the molecular mechanisms for the impaired preadipocyte differentiation in the subcutaneous adipose tissue in hypertrophic obesity is a priority since it may lead to new ways of treating obesity and its associated metabolic complications.

scholarly journals Puerarin Attenuates Obesity-Induced Inflammation and Dyslipidemia by Regulating Macrophages and TNF-Alpha in Obese Mice

Biomedicines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 175
Author(s):  
Ji-Won Noh ◽  
Hee-Kwon Yang ◽  
Min-Soo Jun ◽  
Byung-Cheol Lee
Keyword(s):  
Adipose Tissue ◽  
In Silico ◽  
Tolerance Test ◽  
Low Grade ◽  
Adipocyte Size ◽  
Metabolic Complications ◽  
Immunological Mechanisms ◽  
Tnf Α ◽  
Test Serum

Obesity causes low-grade inflammation that results in dyslipidemia and insulin resistance. We evaluated the effect of puerarin on obesity and metabolic complications both in silico and in vivo and investigated the underlying immunological mechanisms. Twenty C57BL/6 mice were divided into four groups: normal chow, control (HFD), HFD + puerarin (PUE) 200 mg/kg, and HFD + atorvastatin (ATO) 10 mg/kg groups. We examined bodyweight, oral glucose tolerance test, serum insulin, oral fat tolerance test, serum lipids, and adipocyte size. We also analyzed the percentage of total, M1, and M2 adipose tissue macrophages (ATMs) and the expression of F4/80, tumor necrosis factor-α (TNF-α), C-C motif chemokine ligand 2 (CCL2), CCL4, CCL5, and C-X-C motif chemokine receptor 4. In silico, we identified the treatment-targeted genes of puerarin and simulated molecular docking with puerarin and TNF, M1, and M2 macrophages based on functionally enriched pathways. Puerarin did not significantly change bodyweight but significantly improved fat pad weight, adipocyte size, fat area in the liver, free fatty acids, triglycerides, total cholesterol, and HDL-cholesterol in vivo. In addition, puerarin significantly decreased the ATM population and TNF-α expression. Therefore, puerarin is a potential anti-obesity treatment based on its anti-inflammatory effects in adipose tissue.

scholarly journals JAZF1 heterozygous knockout mice show altered adipose development and metabolism

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jain Jeong ◽  
Soyoung Jang ◽  
Song Park ◽  
Wookbong Kwon ◽  
Si-Yong Kim ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Knockout Mice ◽  
Metabolic Disorders ◽  
Adipocyte Differentiation ◽  
Zinc Finger Protein ◽  
Tissue Mass ◽  
In Vivo Models ◽  
Brown Adipose

Abstract Background Juxtaposed with another zinc finger protein 1 (JAZF1) is associated with metabolic disorders, including type 2 diabetes mellitus (T2DM). Several studies showed that JAZF1 and body fat mass are closely related. We attempted to elucidate the JAZF1 functions on adipose development and related metabolism using in vitro and in vivo models. Results The JAZF1 expression was precisely regulated during adipocyte differentiation of 3T3-L1 preadipocyte and mouse embryonic fibroblasts (MEFs). Homozygous JAZF1 deletion (JAZF1-KO) resulted in impaired adipocyte differentiation in MEF. The JAZF1 role in adipocyte differentiation was demonstrated by the regulation of PPARγ—a key regulator of adipocyte differentiation. Heterozygous JAZF1 deletion (JAZF1-Het) mice fed a normal diet (ND) or a high-fat diet (HFD) had less adipose tissue mass and impaired glucose homeostasis than the control (JAZF1-Cont) mice. However, other metabolic organs, such as brown adipose tissue and liver, were negligible effect on JAZF1 deficiency. Conclusion Our findings emphasized the JAZF1 role in adipocyte differentiation and related metabolism through the heterozygous knockout mice. This study provides new insights into the JAZF1 function in adipose development and metabolism, informing strategies for treating obesity and related metabolic disorders.

scholarly journals The depot-specific and essential roles of CBP/p300 in regulating adipose plasticity

2019 ◽  
Vol 240 (2) ◽  
pp. 257-269 ◽  
Author(s):  
Maria Namwanje ◽  
Longhua Liu ◽  
Michelle Chan ◽  
Nikki Aaron ◽  
Michael J Kraakman ◽  
...  
Keyword(s):  
Body Weight ◽  
Glucose Metabolism ◽  
Glucose Tolerance ◽  
Knockout Mice ◽  
Metabolic Disorders ◽  
Physiological Effects ◽  
Double Knockout ◽  
Adipose Tissues ◽  
Diet Induced Obesity ◽  
Specific Deletion

Fat remodeling has been extensively explored through protein deacetylation, but not yet acetylation, as a viable therapeutic approach in the management of obesity and related metabolic disorders. Here, we investigated the functions of key acetyltransferases CBP/p300 in adipose remodeling and their physiological effects by generating adipose-specific deletion of CBP (Cbp-AKO), p300 (p300-AKO) and double-knockout (Cbp/p300-AKO) models. We demonstrated that Cbp-AKO exhibited marked brown remodeling of inguinal WAT (iWAT) but not epididymal WAT (eWAT) after cold exposure and that this pattern was exaggerated in diet-induced obesity (DIO). Despite this striking browning phenotype, loss of Cbp was insufficient to impact body weight or glucose tolerance. In contrast, ablation of p300 in adipose tissues had minimal effects on fat remodeling and adiposity. Surprisingly, double-knockout mice (Cbp/p300-AKO) developed severe lipodystrophy along with marked hepatic steatosis, hyperglycemia and hyperlipidemia. Furthermore, we demonstrated that pharmacological inhibition of Cbp and p300 activity suppressed adipogenesis. Collectively, these data suggest that (i) CBP, but not p300, has distinct functions in regulating fat remodeling and that this occurs in a depot-selective manner; (ii) brown remodeling occurs independently of the improvements in glucose metabolism and obesity and (iii) the combined roles of CBP and p300 are indispensable for normal adipose development.

Abstract 17023: Adipose Tissue Specific Temporal Deletion of Ager Induces Weight Loss in Diet Induced Obese Mice and Improves Glucose Homeostasis

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Robin Wilson ◽  
Lakshmi Arivazhagan ◽  
Henry Ruiz ◽  
Jay Pendse ◽  
Laura Frye ◽  
...  
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Adipose Tissue ◽  
Glucose Homeostasis ◽  
Fasting Glucose ◽  
Obese Mice ◽  
Gene Encoding ◽  
Low Fat Diet ◽  
Insulin Tolerance ◽  
Specific Deletion

Introduction: The incidence of obesity and its comorbidities is increasing at an alarming rate in US and around the globe. Our previous studies showed that the receptor for advanced glycation end products (RAGE) and its ligands contribute to the pathogenesis of obesity and insulin resistance (IR), as global Ager (gene encoding RAGE) and adipocyte-specific Ager- deleted mice fed a high fat diet (HFD) showed protection from weight gain and IR. However, the role of Ager deletion in mice with established obesity, switched to low fat diet has not been tested. We hypothesize that temporal adipocyte-specific deletion of Ager in obese mice could enhance weight loss and improves glucose homeostasis. Methods: Mice with conditional adipocyte-specific Ager deletion were generated by breeding Ager flox/flox mice with AdipoQ ERT2 Cre recombinase mice resulting in Ager flox/flox / AdipoQ ERT2 Cre (+) and Cre (-) animals. Mice were fed HFD (60% kcal/fat) for 20 weeks starting at 8 weeks of age to establish obesity and were then treated with tamoxifen (TAM) (75 mg/kg per day x 3 alternative days) to induce deletion of Ager . After 4 weeks of TAM treatment, mice were switched to standard chow for 7 weeks and body weight was monitored regularly. Fasting glucose, insulin and glucose tolerance was measured. Results: After 7 weeks of switching to standard chow following TAM, Cre (+) lost significantly more body weight whereas Cre (-) mice showed no significant weight loss over 7 weeks. Furthermore, Cre (+) mice exhibited significantly higher food intake, lower fasting glucose, lower epididymal and inguinal white adipose tissue weights, and improved glucose and insulin tolerance compared to Cre (-) mice. Conclusions: Temporal adipocyte-specific deletion of Ager in mice with established obesity promotes weight loss and improves glucose homeostasis. RAGE may act as a novel therapeutic target in obesity.

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