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Xiang X, Ji R, Han S, Xu X, Zhu S, Li Y, Du J, Mai K, Ai Q. Differences in diacylglycerol acyltransferases expression patterns and regulation cause distinct hepatic triglyceride deposition in fish. Commun Biol 2024; 7:480. [PMID: 38641731 PMCID: PMC11031565 DOI: 10.1038/s42003-024-06022-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 03/07/2024] [Indexed: 04/21/2024] Open
Abstract
Triglyceride (TAG) deposition in the liver is associated with metabolic disorders. In lower vertebrate, the propensity to accumulate hepatic TAG varies widely among fish species. Diacylglycerol acyltransferases (DGAT1 and DGAT2) are major enzymes for TAG synthesis. Here we show that large yellow croaker (Larimichthys crocea) has significantly higher hepatic TAG level than that in rainbow trout (Oncorhynchus mykiss) fed with same diet. Hepatic expression of DGATs genes in croaker is markedly higher compared with trout under physiological condition. Meanwhile, DGAT1 and DGAT2 in both croaker and trout are required for TAG synthesis and lipid droplet formation in vitro. Furthermore, oleic acid treatment increases DGAT1 expression in croaker hepatocytes rather than in trout and has no significant difference in DGAT2 expression in two fish species. Finally, effects of various transcription factors on croaker and trout DGAT1 promoter are studied. We find that DGAT1 is a target gene of the transcription factor CREBH in croaker rather than in trout. Overall, hepatic expression and transcriptional regulation of DGATs display significant species differences between croaker and trout with distinct hepatic triglyceride deposition, which bring new perspectives on the use of fish models for studying hepatic TAG deposition.
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Affiliation(s)
- Xiaojun Xiang
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Renlei Ji
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Shangzhe Han
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Xiang Xu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Si Zhu
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Yongnan Li
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Jianlong Du
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
| | - Kangsen Mai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Qingdao, Shandong, 266237, People's Republic of China
| | - Qinghui Ai
- Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture and Rural Affairs) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong, 266003, P.R. China.
- Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, 1 Wenhai Road, Qingdao, Shandong, 266237, People's Republic of China.
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Wang Y, Zhou Y, Zhou X, Su X, Xu X, Li H, Ma J. Effect of Chiglitazar and Sitagliptin on Bone Mineral Density and Body Composition in Untreated Patients with Type 2 Diabetes. Diabetes Metab Syndr Obes 2023; 16:4205-4214. [PMID: 38162801 PMCID: PMC10757783 DOI: 10.2147/dmso.s439479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Accepted: 12/14/2023] [Indexed: 01/03/2024] Open
Abstract
Aim To evaluate the changes in bone mineral density (BMD) and body composition in untreated patients with type 2 diabetes mellitus (T2DM) before and after chiglitazar or sitagliptin treatment. Methods A total of 81 patients with T2DM were randomly divided to receive chiglitazar or sitagliptin treatment for 24 weeks (54 in the chiglitazar group and 27 in the sitagliptin group). We measured the spine lumbar BMD, hip BMD, fat mass (FM), fat-free mass (FFM), percent body fat (%BF), android FM, gynoid FM and skeleton muscle mass (SMM) using dual-energy X-ray absorptiometry (DEXA) and examined serum adiponectin (ADP) levels at baseline and the end of the study. Results There were no significant changes in the BMD of the L2-4, femoral neck, trochanter or total hip as well as in the BMC after 24 weeks of treatment with chiglitazar or sitagliptin. After chiglitazar administration, the FM, gynoid FM and gynoid to total FM ratio were higher, while the android to total FM ratio and the android to gynoid FM ratio (AOI) were significantly lower. Sitagliptin intervention did not result in statistically significant differences in total fat loss, but it did cause significant decreases in %BF and AOI as well as increases in the FFM, gynoid to total FM ratio and SMM. The ADP levels had significantly negative associations with AOI in all eligible patients. Conclusion The chiglitazar had no deleterious effects on BMD and resulted in body fat redistribution in untreated patients with T2DM. Trial Registration The trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT02173457).
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Affiliation(s)
- Yuming Wang
- Department of Geriatrics, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, People’s Republic of China
- Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210012, People’s Republic of China
| | - Yunting Zhou
- Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210012, People’s Republic of China
| | - Xiao Zhou
- Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210012, People’s Republic of China
| | - Xiaofei Su
- Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210012, People’s Republic of China
| | - Xiaohua Xu
- Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210012, People’s Republic of China
| | - Huiqin Li
- Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210012, People’s Republic of China
| | - Jianhua Ma
- Department of Endocrinology, Nanjing First Hospital, Nanjing Medical University, Nanjing, 210012, People’s Republic of China
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Naomi R, Yazid MD, Bahari H, Keong YY, Rajandram R, Embong H, Teoh SH, Halim S, Othman F. Bisphenol A (BPA) Leading to Obesity and Cardiovascular Complications: A Compilation of Current In Vivo Study. Int J Mol Sci 2022; 23:2969. [PMID: 35328389 PMCID: PMC8949383 DOI: 10.3390/ijms23062969] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/24/2022] [Accepted: 03/01/2022] [Indexed: 02/06/2023] Open
Abstract
BPA is one of the most common endocrine disruptors that is widely being manufactured daily nationwide. Although scientific evidence supports claims of negative effects of BPA on humans, there is also evidence suggesting that a low level of BPA is safe. However, numerous in vivo trials contraindicate with this claim and there is a high possibility of BPA exposure could lead to obesity. It has been speculated that this does not stop with the exposed subjects only, but may also cause transgenerational effects. Direct disruption of endocrine regulation, neuroimmune and signaling pathways, as well as gut microbiata, has been identified to be interrupted by BPA exposure, leading to overweight or obesity. In these instances, cardiovascular complications are one of the primary notable clinical signs. In regard to this claim, this review paper discusses the role of BPA on obesity in the perspective of endocrine disruptions and possible cardiovascular complications that may arise due to BPA. Thus, the aim of this review is to outline the changes in gut microbiota and neuroimmune or signaling mechanisms involved in obesity in relation to BPA. To identify potentially relevant articles, a depth search was done on the databases Nature, PubMed, Wiley Online Library, and Medline & Ovid from the past 5 years. According to Boolean operator guideline, selected keywords such as (1) BPA OR environmental chemical AND fat OR LDL OR obese AND transgenerational effects or phenocopy (2) Endocrine disruptors OR chemical AND lipodystrophy AND phenocopy (3) Lipid profile OR weight changes AND cardiovascular effect (4) BPA AND neuroimmune OR gene signaling, were used as search terms. Upon screening, 11 articles were finalized to be further reviewed and data extraction tables containing information on (1) the type of animal model (2) duration and dosage of BPA exposure (3) changes in the lipid profile or weight (4) genes, signaling mechanism, or any neuroimmune signal involved, and (5) transgenerational effects were created. In toto, the study indicates there are high chances of BPA exposure affecting lipid profile and gene associated with lipolysis, leading to obesity. Therefore, this scoping review recapitulates the possible effects of BPA that may lead to obesity with the evidence of current in vivo trials. The biomarkers, safety concerns, recommended dosage, and the impact of COVID-19 on BPA are also briefly described.
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Affiliation(s)
- Ruth Naomi
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
| | - Muhammad Dain Yazid
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Kuala Lumpur 56000, Malaysia
| | - Hasnah Bahari
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
| | - Yong Yoke Keong
- Department of Human Anatomy, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia
| | - Retnagowri Rajandram
- Department of Surgery, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Hashim Embong
- Department of Emergency Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia
| | - Soo Huat Teoh
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, Penang 13200, Malaysia
| | - Shariff Halim
- Neuroscience Research Group, International Medical School, Management & Science University, University Drive, Off Persiaran Olahraga, Shah Alam 40100, Malaysia
| | - Fezah Othman
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang 43400, Malaysia
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Adipocyte Phenotype Flexibility and Lipid Dysregulation. Cells 2022; 11:cells11050882. [PMID: 35269504 PMCID: PMC8909878 DOI: 10.3390/cells11050882] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/22/2022] [Accepted: 03/01/2022] [Indexed: 12/04/2022] Open
Abstract
The prevalence of obesity and associated cardiometabolic diseases continues to rise, despite efforts to improve global health. The adipose tissue is now regarded as an endocrine organ since its multitude of secretions, lipids chief among them, regulate systemic functions. The loss of normal adipose tissue phenotypic flexibility, especially related to lipid homeostasis, appears to trigger cardiometabolic pathogenesis. The goal of this manuscript is to review lipid balance maintenance by the lean adipose tissue’s propensity for phenotype switching, obese adipose tissue’s narrower range of phenotype flexibility, and what initial factors account for the waning lipid regulatory capacity. Metabolic, hypoxic, and inflammatory factors contribute to the adipose tissue phenotype being made rigid. A better grasp of normal adipose tissue function provides the necessary context for recognizing the extent of obese adipose tissue dysfunction and gaining insight into how pathogenesis evolves.
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Ye RZ, Richard G, Gévry N, Tchernof A, Carpentier AC. Fat Cell Size: Measurement Methods, Pathophysiological Origins, and Relationships With Metabolic Dysregulations. Endocr Rev 2022; 43:35-60. [PMID: 34100954 PMCID: PMC8755996 DOI: 10.1210/endrev/bnab018] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Indexed: 11/19/2022]
Abstract
The obesity pandemic increasingly causes morbidity and mortality from type 2 diabetes, cardiovascular diseases and many other chronic diseases. Fat cell size (FCS) predicts numerous obesity-related complications such as lipid dysmetabolism, ectopic fat accumulation, insulin resistance, and cardiovascular disorders. Nevertheless, the scarcity of systematic literature reviews on this subject is compounded by the use of different methods by which FCS measurements are determined and reported. In this paper, we provide a systematic review of the current literature on the relationship between adipocyte hypertrophy and obesity-related glucose and lipid dysmetabolism, ectopic fat accumulation, and cardiovascular disorders. We also review the numerous mechanistic origins of adipocyte hypertrophy and its relationship with metabolic dysregulation, including changes in adipogenesis, cell senescence, collagen deposition, systemic inflammation, adipokine secretion, and energy balance. To quantify the effect of different FCS measurement methods, we performed statistical analyses across published data while controlling for body mass index, age, and sex.
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Affiliation(s)
- Run Zhou Ye
- Division of Endocrinology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Gabriel Richard
- Division of Endocrinology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Nicolas Gévry
- Department of Biology, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - André Tchernof
- Québec Heart and Lung Research Institute, Laval University, Québec, Québec, Canada
| | - André C Carpentier
- Division of Endocrinology, Department of Medicine, Centre de recherche du Centre hospitalier universitaire de Sherbrooke, Université de Sherbrooke, Sherbrooke, Québec, Canada
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Jia Q, Carranza Leon BG, Jensen MD. Influence of Free Fatty Acid Concentrations and Weight Loss on Adipose Tissue Direct Free Fatty Acid Storage Rates. J Clin Endocrinol Metab 2021; 106:e5165-e5179. [PMID: 34251018 PMCID: PMC8864754 DOI: 10.1210/clinem/dgab501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Indexed: 02/08/2023]
Abstract
CONTEXT The factors that determine the recycling of free fatty acids (FFA) back into different adipose tissue depots via the direct storage pathway are not completely understood. OBJECTIVE To assess the interactions between adipocyte factors and plasma FFA concentrations that determine regional FFA storage rates. DESIGN We measured direct adipose tissue FFA storage rates before and after weight loss under high FFA (intravenous somatostatin and epinephrine) and low (intravenous insulin and glucose) FFA concentrations. SETTING Mayo Clinic Clinical Research Unit. PATIENTS Sixteen premenopausal women, body mass index 30 to 37 kg/m2. INTERVENTION Comprehensive lifestyle weight loss program. MAIN OUTCOME MEASURE Direct FFA storage rates in upper and lower body subcutaneous fat. RESULTS Over the entire range of FFA and under isolated conditions of elevated FFA concentrations, the storage rates of FFA into upper and lower body subcutaneous fat per unit lipid were associated with concentrations, not adipocyte fatty acid storage factors. Under low FFA conditions, direct FFA storage rates were related to adipocyte CD36 content, not tissue level content of fatty acid storage factors. Weight loss did not change these relationships. CONCLUSIONS The regulation of direct FFA storage under low FFA concentration conditions appears to be at the level of the cell/adipocyte content of CD36, whereas under high FFA concentration conditions, direct FFA storage at the tissue level is predicted by plasma FFA concentrations, independent of adipocyte size or fatty acid storage factors. These observations offer novel insights into how adipose tissue regulates direct FFA storage in humans.
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Affiliation(s)
- Qingyi Jia
- Department of Endocrinology and Metabolism, West China Hospital, Sichuan University, Chengdu, China
- Endocrine Research Unit, Mayo Clinic, Rochester, MN, USA
| | - B Gisella Carranza Leon
- Division of Diabetes, Endocrinology and Metabolism, Vanderbilt University Medical Center, Nashville, TN, USA
- Endocrine Research Unit, Mayo Clinic, Rochester, MN, USA
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7
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Lytle KA, Bush NC, Triay JM, Kellogg TA, Kendrick ML, Swain JM, Gathaiya NW, Hames KC, Jensen MD. Adipocyte Proteins and Storage of Endogenous Fatty Acids in Visceral and Subcutaneous Adipose Tissue in Severe Obesity. Obesity (Silver Spring) 2021; 29:1014-1021. [PMID: 33893721 PMCID: PMC8154683 DOI: 10.1002/oby.23149] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/25/2021] [Accepted: 02/11/2021] [Indexed: 11/11/2022]
Abstract
OBJECTIVE This study tested whether substrate concentrations or fatty acid storage proteins predict storage of endogenous lipids in visceral adipose tissue (VAT) and upper body subcutaneous adipose tissue (UBSQ) fat. METHODS The day prior to surgery, 25 patients undergoing bariatric procedures received an infusion of autologous [1-14 C]triolein-labeled very low-density lipoprotein (VLDL) particles, and during surgery, they received a continuous [U-13 C]palmitate infusion/bolus [9,10-3 H]palmitate tracer. VAT and UBSQ fat were collected to measure VLDL-triglyceride (TG) storage, direct free fatty acid (FFA) storage rates, CD36 content, lipoprotein lipase (LPL), acyl-CoA synthetase, diacylglycerol acetyl-transferase, and glycerol-3-phosphate acyltransferase activities. RESULTS Storage of VLDL-TG and FFA-palmitate in UBSQ and VAT was not different. Plasma palmitate concentrations correlated with palmitate storage rates in UBSQ and VAT (r = 0.46, P = 0.02 and r = 0.46, P = 0.02, respectively). In VAT, VLDL-TG storage was correlated with VLDL concentrations (r = 0.53, P < 0.009) and LPL (r = 0.42, P < 0.05). In UBSQ, VLDL-TG storage was correlated with LPL (r = 0.42, P < 0.05). CD36, acyl-CoA synthetase, glycerol-3-phosphate acyltransferase, and diacylglycerol acetyl-transferase were not correlated with VLDL-TG or palmitate storage. CONCLUSIONS Adipose storage of VLDL-TG is predicted by VLDL-TG concentrations and LPL; FFA concentrations predict direct adipose tissue FFA storage rates.
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Affiliation(s)
- Kelli A. Lytle
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota, USA
| | - Nikki C. Bush
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota, USA
| | | | - Todd A. Kellogg
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, USA
| | | | - James M. Swain
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, USA
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Zhang L, Hames KC, Jensen MD. Regulation of direct adipose tissue free fatty acid storage during mixed meal ingestion and high free fatty acid concentration conditions. Am J Physiol Endocrinol Metab 2021; 320:E208-E218. [PMID: 33196297 PMCID: PMC8260364 DOI: 10.1152/ajpendo.00408.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We found that direct free fatty acid (FFA) storage (fatty acid cycling back into adipose tissue) in leg vs. abdominal subcutaneous fat is related to regional differences in adipose tissue diacylglycerol acyltransferase (DGAT) activity under high-FFA conditions and to differences in adipose tissue acyl-CoA synthetase (ACS)activity under meal ingestion conditions. We also found that direct FFA storage rates in leg fat were significantly less in physically active than sedentary adults. Direct FFA storage into adipocytes relates to body fat distribution. Adipose tissue CD36, ACS, and DGAT may account for some of the between-depot and interindividual variability in FFA storage. These studies were to test whether CD36, ACS, or DGAT might be important for direct palmitate storage under meal ingestion or high-FFA conditions. We measured upper (UBSQ) and lower body subcutaneous (LBSQ) adipose tissue FFA storage rates by infusing palmitate tracers intravenously and performing adipose biopsies under hypoinsulinemic (high-FFA) and mixed-meal conditions. We recruited five postmenopausal women, physically active males (5) and females (5), and sedentary males (5) and females (5). We found that 1) the ratio of UBSQ to LBSQ DGAT activity predicted the ratio of palmitate storage [adjusted R = 0.25, F = 8.0, P = 0.01, 95% CI (0.07, 0.48)] under high-FFA conditions; 2) the ratio of UBSQ to LBSQ ACS activity predicted the ratio of palmitate storage under meal conditions [adjusted R = 0.18, F = 6.3, P = 0.02, 95% CI (0.12, 1.28)]; 3) LBSQ direct palmitate storage rates were significantly less in physically active than sedentary and 4) adipose tissue CD36 protein content, ACS, or DGAT activities did not independently predict palmitate storage rates. We conclude that physically active adults have lesser fatty acid cycling back into adipose tissue and that adipose ACS and DGAT may affect competition between UBSQ and LBSQ adipose for direct palmitate storage.
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Affiliation(s)
- Lili Zhang
- Department of Endocrinology, the Second Affiliated Hospital, Chongqing Medical University, Chongqing, China
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Kazanna C Hames
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
- Dexcom, San Diego, California
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Czech MP. Mechanisms of insulin resistance related to white, beige, and brown adipocytes. Mol Metab 2020; 34:27-42. [PMID: 32180558 PMCID: PMC6997501 DOI: 10.1016/j.molmet.2019.12.014] [Citation(s) in RCA: 109] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/21/2019] [Accepted: 12/23/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The diminished glucose lowering effect of insulin in obesity, called "insulin resistance," is associated with glucose intolerance, type 2 diabetes, and other serious maladies. Many publications on this topic have suggested numerous hypotheses on the molecular and cellular disruptions that contribute to the syndrome. However, significant uncertainty remains on the mechanisms of its initiation and long-term maintenance. SCOPE OF REVIEW To simplify insulin resistance analysis, this review focuses on the unifying concept that adipose tissue is a central regulator of systemic glucose homeostasis by controlling liver and skeletal muscle metabolism. Key aspects of adipose function related to insulin resistance reviewed are: 1) the modes by which specific adipose tissues control hepatic glucose output and systemic glucose disposal, 2) recently acquired understanding of the underlying mechanisms of these modes of regulation, and 3) the steps in these pathways adversely affected by obesity that cause insulin resistance. MAJOR CONCLUSIONS Adipocyte heterogeneity is required to mediate the multiple pathways that control systemic glucose tolerance. White adipocytes specialize in sequestering triglycerides away from the liver, muscle, and other tissues to limit toxicity. In contrast, brown/beige adipocytes are very active in directly taking up glucose in response to β adrenergic signaling and insulin and enhancing energy expenditure. Nonetheless, white, beige, and brown adipocytes all share the common feature of secreting factors and possibly exosomes that act on distant tissues to control glucose homeostasis. Obesity exerts deleterious effects on each of these adipocyte functions to cause insulin resistance.
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Affiliation(s)
- Michael P Czech
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
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10
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Haczeyni F, Bell-Anderson KS, Farrell GC. Causes and mechanisms of adipocyte enlargement and adipose expansion. Obes Rev 2018; 19:406-420. [PMID: 29243339 DOI: 10.1111/obr.12646] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 09/28/2017] [Accepted: 10/23/2017] [Indexed: 02/06/2023]
Abstract
Adipose tissue plays a significant role in whole body energy homeostasis. Obesity-associated diabetes, fatty liver and metabolic syndrome are closely linked to adipose stress and dysfunction. Genetic predisposition, overeating and physical inactivity influence the expansion of adipose tissues. Under conditions of constant energy surplus, adipocytes become hypertrophic and adipose tissues undergo hyperplasia so as to increase their lipid storage capacity, thereby keeping circulating blood glucose and fatty acids below toxic levels. Nonetheless, adipocytes have a saturation point where they lose capacity to store more lipids. At this stage, when adipocytes are fully lipid-engorged, they express stress signals. Adipose depots (particularly visceral compartments) from obese individuals with a severe metabolic phenotype are characterized by the high proportion of hypertrophic adipocytes. This review focuses on the mechanisms of adipocyte enlargement in relation to adipose fatty acid and cholesterol metabolism, and considers how this may be related to adipose dysfunction.
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Affiliation(s)
- F Haczeyni
- Liver Research Group, Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia
| | - K S Bell-Anderson
- Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
| | - G C Farrell
- Liver Research Group, Australian National University Medical School at The Canberra Hospital, Canberra, ACT, Australia
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11
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Søndergaard E, Johansen RF, Jensen MD, Nielsen S. Postprandial VLDL-TG metabolism in type 2 diabetes. Metabolism 2017; 75:25-35. [PMID: 28964326 DOI: 10.1016/j.metabol.2017.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 06/26/2017] [Accepted: 07/05/2017] [Indexed: 01/22/2023]
Abstract
BACKGROUND Type 2 diabetes is associated with excess postprandial lipemia due to accumulation of chylomicrons and VLDL particles. This is a risk factor for development of cardiovascular disease. However, whether the excess lipemia is associated with an impaired suppression of VLDL-TG secretion and/or reduced clearance into adipose tissue is unknown. OBJECTIVE We measured the postprandial VLDL-TG secretion, clearance and adipose tissue storage to test the hypothesis that impaired postprandial suppression of VLDL-TG secretion, combined with impaired VLDL-TG storage in adipose tissue, is associated with excess postprandial lipemia. DESIGN We studied 11 men with type 2 diabetes and 10 weight-matched non-diabetic men using ex-vivo labeled VLDL-TG tracers during an oral high-fat mixed-meal tolerance test to measure postprandial VLDL-TG secretion, clearance and storage. In addition, adipose tissue biopsies were analyzed for LPL activity and cellular storage factors. RESULTS Men with type 2 diabetes had greater postprandial VLDL-TG concentration compared to non-diabetic men. However, postprandial VLDL-TG secretion rate was similar in the two groups with equal suppression of VLDL-TG secretion rate (≈50%) and clearance rate. In addition, postprandial VLDL-TG storage was similar in the two groups in both upper body and lower body subcutaneous adipose tissue. CONCLUSIONS Despite greater postprandial VLDL-TG concentration, men with type 2 diabetes have similar postprandial suppression of VLDL-TG secretion and a similar ability to store VLDL-TG in adipose tissue compared to non-diabetic men. This may indicate that abnormalities in postprandial VLDL-TG metabolism are a consequence of obesity/insulin resistance more than a result of type 2 diabetes per se.
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Affiliation(s)
- Esben Søndergaard
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark; Danish Diabetes Academy, Odense University Hospital, Kløvervænget 10, Entrance 112, 3rd floor, 5000 Odense C, Denmark; Endocrine Research Unit, Mayo Clinic, 1216 2nd St SW, Rochester, MN 55902, USA.
| | - Rakel Fuglsang Johansen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark
| | - Michael D Jensen
- Endocrine Research Unit, Mayo Clinic, 1216 2nd St SW, Rochester, MN 55902, USA
| | - Søren Nielsen
- Department of Endocrinology and Internal Medicine, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark
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Abstract
CONTEXT Although the long-term effects of testosterone on adipose tissue lipid metabolism in men have been defined, the short-term regulation of these effects is not well understood. OBJECTIVE We examined the effects of acute testosterone withdrawal on subcutaneous abdominal and femoral adipose tissue fatty acid (FA) storage and cellular mechanisms. DESIGN This was a prospective, randomized trial. SETTING Mayo Clinic Clinical Research Unit. PATIENTS OR PARTICIPANTS Thirty-two male volunteers ages 18 to 50 participated in these studies. INTERVENTIONS Volunteers were randomized to receive (1) no treatment (control), (2) injections (7.5 mg) of Lupron®, or (3) Lupron and testosterone (L+T) replacement for 49 days, resulting in 4 weeks of sex steroid suppression in the Lupron group. MAIN OUTCOME MEASURES We measured body composition, fat cell size, adipose tissue meal FA and direct free FA storage, lipoprotein lipase (LPL), acyl coenzyme A synthetase (ACS), diacylglycerol acyltransferase activities, and CD36 content. RESULTS Compared with control and L+T groups, acute testosterone deficiency resulted in greater femoral adipose tissue meal FA storage rates, fasting and fed LPL activity, and ACS activity. CONCLUSIONS These results suggest that in men, testosterone plays a tonic role in restraining FA storage in femoral adipose tissue via suppression of LPL and ACS activities. FA storage mechanisms in men appear sensitive to short-term changes in testosterone concentrations.
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Affiliation(s)
- Sylvia Santosa
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905
- Department of Exercise Science, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Nikki C. Bush
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905
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Andersen IR, Søndergaard E, Sørensen LP, Nellemann B, Gormsen LC, Jensen MD, Nielsen S. Increased VLDL-TG Fatty Acid Storage in Skeletal Muscle in Men With Type 2 Diabetes. J Clin Endocrinol Metab 2017; 102:831-839. [PMID: 27898284 DOI: 10.1210/jc.2016-2979] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 11/28/2016] [Indexed: 12/19/2022]
Abstract
CONTEXT Lipoprotein lipase (LPL) activity is considered the rate-limiting step of very-low-density-lipoprotein triglycerides (VLDL-TG) tissue storage, and has been suggested to relate to the development of obesity as well as insulin resistance and type 2 diabetes. OBJECTIVE The objective of the study was to assess the relationship between the quantitative storage of VLDL-TG fatty acids and LPL activity and other storage factors in muscle and adipose tissue. In addition, we examine whether such relations were influenced by type 2 diabetes. DESIGN We recruited 23 men (12 with type 2 diabetes, 11 nondiabetic) matched for age and body mass index. Postabsorptive VLDL-TG muscle and subcutaneous adipose tissue (abdominal and leg) quantitative storage was measured using tissue biopsies in combination with a primed-constant infusion of ex vivo triolein labeled [1-14C]VLDL-TG and a bolus infusion of ex vivo triolein labeled [9,10-3H]VLDL-TG. Biopsies were analyzed for LPL activity and cellular storage factors. RESULTS VLDL-TG storage rate was significantly greater in men with type 2 diabetes compared with nondiabetic men in muscle tissue (P = 0.02). We found no significant relationship between VLDL-TG storage rate and LPL activity or other storage factors in muscle or adipose tissue. However, LPL activity correlated with fractional VLDL-TG storage in abdominal fat (P = 0.04). CONCLUSIONS Men with type 2 diabetes have increased VLDL-TG storage in muscle tissue, potentially contributing to increased intramyocellular triglyceride and ectopic lipid deposition. Neither muscle nor adipose tissue storage rates were related to LPL activity. This argues against LPL as a rate-limiting step in the postabsorptive quantitative storage of VLDL-TG.
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Affiliation(s)
| | - Esben Søndergaard
- Departments of Endocrinology and Internal Medicine and
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905; and
- Danish Diabetes Academy, 5000 Odense, Denmark
| | | | | | - Lars C Gormsen
- Department of Nuclear Medicine and PET Center, Aarhus University Hospital, 8000 Aarhus, Denmark
| | - Michael D Jensen
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905; and
| | - Søren Nielsen
- Departments of Endocrinology and Internal Medicine and
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Santosa S, Bonnes SL, Jensen MD. Acute Female Hypogonadism Alters Adipose Tissue Fatty Acid Storage Factors and Chylomicronemia. J Clin Endocrinol Metab 2016; 101:2089-98. [PMID: 27003301 PMCID: PMC4870847 DOI: 10.1210/jc.2015-4065] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
CONTEXT Chronic sex steroid deficiency has effects on adipose fatty acid (FA) storage mechanisms and fat oxidation, but the chronology of events are not well understood. OBJECTIVE The objective of the study was to examine the acute effects of female sex steroid suppression on cellular mechanisms affecting abdominal and femoral subcutaneous adipose tissue FA storage. DESIGN This study had a randomized, longitudinal, parallel study design. SETTING The study was conducted at the Mayo Clinic Clinical Research Unit. PARTICIPANTS Thirty-eight nonsmoking premenopausal women aged 18-50 years participated in the study. INTERVENTION The intervention included randomization to receive one of the following: 1) no treatment (control), 2) 3.75 mg of Lupron, or 3) 3.75 mg of Lupron and estrogen, but not progesterone, replacement for 49 days, resulting in at least 4 weeks of sex steroid suppression. MAIN OUTCOME MEASURES Body composition, fat cell size, postprandial chylomicron and nonchylomicron triglyceride concentrations, adipose tissue meal FA storage, direct free fatty acid storage, lipoprotein lipase, acyl CoA synthetase, and diacylglycerol acyltransferase activities, and CD36 content were measured. RESULTS Compared with the control group, the fed state femoral lipoprotein lipase activity was reduced in women taking Lupron and those taking Lupron and estrogen replacement. In addition, we observed significantly greater postprandial chylomicronemia in the Lupron group than in the other two groups. There were no differences in overall fat storage and oxidation. Depending on the mode of data expression (per unit lipid vs per 1000 adipocytes), there were modest changes in acyl CoA synthetase, diacylglycerol acyltransferase, and CD36 in response to acute sex hormone suppression. CONCLUSIONS Our results suggest estrogen and progesterone may have different effects on the regulation of FA metabolism and that acute sex steroid deficiency in women does not alter fat storage and oxidation.
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Affiliation(s)
- Sylvia Santosa
- Endocrine Research Unit (S.S., M.D.J.), and Department of General Internal Medicine (S.L.B.), Mayo Clinic, Rochester, Minnesota 55905; and Department of Exercise Science (S.S.), and PERFORM Centre (S.S.) Concordia University, Montréal, Québec, Canada H4B 1R6
| | - Sara L Bonnes
- Endocrine Research Unit (S.S., M.D.J.), and Department of General Internal Medicine (S.L.B.), Mayo Clinic, Rochester, Minnesota 55905; and Department of Exercise Science (S.S.), and PERFORM Centre (S.S.) Concordia University, Montréal, Québec, Canada H4B 1R6
| | - Michael D Jensen
- Endocrine Research Unit (S.S., M.D.J.), and Department of General Internal Medicine (S.L.B.), Mayo Clinic, Rochester, Minnesota 55905; and Department of Exercise Science (S.S.), and PERFORM Centre (S.S.) Concordia University, Montréal, Québec, Canada H4B 1R6
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Morgan-Bathke M, Chen L, Oberschneider E, Harteneck D, Jensen MD. More insights into a human adipose tissue GPAT activity assay. Adipocyte 2016; 5:93-6. [PMID: 27144101 DOI: 10.1080/21623945.2015.1068977] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 06/24/2015] [Accepted: 06/25/2015] [Indexed: 10/23/2022] Open
Abstract
Adipose tissue fatty acid storage varies according to sex, adipose tissue depot and degree of fat gain. However, the mechanism(s) for these variations is not completely understood. We recently published findings based on the glycerol 3-phosphate acyltransferase (GPAT) enzyme activity assay we optimized for use with human adipose tissue. These findings include a decrease in total GPAT and GPAT1 as a function of adipocyte size in both omental and subcutaneous adipose tissue and a strong, positive correlations between ACS, GPAT, and DGAT activities for both sexes and depots and between these storage factors and palmitate storage rates into TAG. The aim of this commentary is to expand upon the data from our recent publication. We describe here additional details on the optimization of the GPAT enzyme activity assay, a correlation between DGAT and percentage palmitate in the diacylglycerol fraction, and sex differences in fatty acid storage factors and storage rates into TAG at high palmitate concentrations.
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The expression of genes involved in jejunal lipogenesis and lipoprotein synthesis is altered in morbidly obese subjects with insulin resistance. J Transl Med 2015; 95:1409-17. [PMID: 26367490 DOI: 10.1038/labinvest.2015.115] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 07/03/2015] [Accepted: 07/28/2015] [Indexed: 12/28/2022] Open
Abstract
The dyslipidemia associated with type 2 diabetes mellitus (T2DM) is an important risk factor for atherosclerotic cardiovascular disease. However, until now little attention has been paid to the role that the intestine might have. The aim of this research was to determine the relation between insulin resistance and intestinal de novo lipogenesis/lipoprotein synthesis in morbidly obese subjects and to study the effect of insulin on these processes. Jejunal mRNA expression of the different genes involved in the intestinal de novo lipogenesis/lipoprotein synthesis was analyzed in three groups of morbidly obese subjects: Group 1 with low insulin resistance (MO-low-IR), group 2 with high insulin resistance (MO-high-IR), and group 3 with T2DM and treatment with metformin (MO-metf-T2DM). In addition, intestinal epithelial cells (IECs) from MO-low-IR were incubated with different doses of insulin/glucose. In Group 2 (MO-high-IR), the jejunal mRNA expression levels of apo A-IV, ATP-citrate lyase (ACLY), pyruvate dehydrogenase (lipoamide) beta (PDHB), and sterol regulatory element-binding protein-1c (SREBP-1c) were significantly higher and acetyl-CoA carboxylase alpha (ACC1) and fatty-acid synthase lower than in Group 1 (MO-low-IR). In Group 3 (MO-metf-T2DM), only the ACLY and PDHB mRNA expressions were significantly higher than in Group 1 (MO-low-IR). The mRNA expression of most of the genes studied was significantly linked to insulin and glucose levels. The incubation of IEC with different doses of insulin and glucose produced a higher expression of diacylglycerol acyltransferase 2, microsomal triglyceride transfer protein, apo A-IV, SREBP-1c, and ACC1 when both, glucose and insulin, were at a high concentration. However, with only high insulin levels, there were higher apo A-IV, PDHB and SREBP-1c expressions, and a lower ACLY expression. In conclusion, the jejunum of MO-high-IR has a decreased mRNA expression of genes involved in de novo fatty-acid synthesis and an increase of genes involved in acetyl-CoA and lipoprotein synthesis. This effect is attenuated by metformin. In addition, the expression of most of the genes studied was found to be regulated by insulin.
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Ali AH, Mundi M, Koutsari C, Bernlohr DA, Jensen MD. Adipose Tissue Free Fatty Acid Storage In Vivo: Effects of Insulin Versus Niacin as a Control for Suppression of Lipolysis. Diabetes 2015; 64:2828-35. [PMID: 25883112 PMCID: PMC4512218 DOI: 10.2337/db14-1409] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 04/10/2015] [Indexed: 11/13/2022]
Abstract
Insulin stimulates the translocation fatty acid transport protein 1 (FATP1) to plasma membrane, and thus greater free fatty acid (FFA) uptake, in adipocyte cell models. Whether insulin stimulates greater FFA clearance into adipose tissue in vivo is unknown. We tested this hypothesis by comparing direct FFA storage in subcutaneous adipose tissue during insulin versus niacin-medicated suppression of lipolysis. We measured direct FFA storage in abdominal and femoral subcutaneous fat in 10 and 11 adults, respectively, during euglycemic hyperinsulinemia or after oral niacin to suppress FFA compared with 11 saline control experiments. Direct palmitate storage was assessed using a [U-(13)C]palmitate infusion to measure palmitate kinetics and an intravenous palmitate radiotracer bolus/timed biopsy. Plasma palmitate concentrations and flux were suppressed to 23 ± 3 and 26 ± 5 µmol ⋅ L(-1) (P = 0.91) and 44 ± 4 and 39 ± 5 µmol ⋅ min(-1) (P = 0.41) in the insulin and niacin groups, respectively, much less (P < 0.001) than the saline control group (102 ± 8 and 104 ± 12 µmol ⋅ min(-1), respectively). In the insulin, niacin, and saline groups, abdominal palmitate storage rates were 0.25 ± 0.05 vs. 0.25 ± 0.07 vs. 0.32 ± 0.05 µmol ⋅ kg adipose lipid(-1) ⋅ min(-1), respectively (P = NS), and femoral adipose storage rates were 0.19 ± 0.06 vs. 0.20 ± 0.05 vs. 0.31 ± 0.05 µmol ⋅ kg adipose lipid(-1) ⋅ min(-1), respectively (P = NS). In conclusion, insulin does not increase FFA storage in adipose tissue compared with niacin, which suppresses lipolysis via a different pathway.
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Affiliation(s)
- Asem H Ali
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN King Abdullah International Medical Research Center, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
| | - Manpreet Mundi
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN
| | - Christina Koutsari
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN
| | - David A Bernlohr
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN
| | - Michael D Jensen
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, MN
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18
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Santosa S, Jensen MD. Sex and sex steroids: impact on the kinetics of fatty acids underlying body shape. Horm Mol Biol Clin Investig 2015; 20:15-23. [PMID: 25460291 DOI: 10.1515/hmbci-2014-0029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 10/28/2014] [Indexed: 11/15/2022]
Abstract
Adult humans have a remarkable sexual dimorphism in body shape. Men tend to store relatively more fat in the upper body whereas women store more fat in the lower body. We do not have a complete understanding of the mechanisms underlying these differences, but we know that people who preferentially store abdominal fat are at greater risk of metabolic disease. It is also known that the changes in sex steroid concentrations during puberty and again with advancing age are accompanied by changes in body fat distribution. The objective of this review is to describe what has been learned regarding the mechanisms underlying changes in regional body fat distribution that occur as a result of changes in sex hormones and to delineate effects of sex steroids in modulating body composition.
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Morgan-Bathke M, Chen L, Oberschneider E, Harteneck D, Jensen MD. Sex and depot differences in ex vivo adipose tissue fatty acid storage and glycerol-3-phosphate acyltransferase activity. Am J Physiol Endocrinol Metab 2015; 308:E830-46. [PMID: 25738782 PMCID: PMC4420896 DOI: 10.1152/ajpendo.00424.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 02/26/2015] [Indexed: 12/20/2022]
Abstract
Adipose tissue fatty acid storage varies according to sex, adipose tissue depot, and degree of fat gain. However, the mechanism(s) for these variations is not completely understood. We examined whether differences in adipose tissue glycerol-3-phosphate acyltransferase (GPAT) might play a role in these variations. We optimized an enzyme activity assay for total GPAT and GPAT1 activity in human adipose tissue and measured GPAT activity. Omental and subcutaneous adipose tissue was collected from obese and nonobese adults for measures of GPAT and GPAT1 activities, ex vivo palmitate storage, acyl-CoA synthetase (ACS) and diacylglycerol-acyltransferase (DGAT) activities, and CD36 protein. Total GPAT and GPAT1 activities decreased as a function of adipocyte size in both omental (r = -0.71, P = 0.003) and subcutaneous (r = -0.58, P = 0.04) fat. The relative contribution of GPAT1 to total GPAT activity increased as a function of adipocyte size, accounting for up to 60% of GPAT activity in those with the largest adipocytes. We found strong, positive correlations between ACS, GPAT, and DGAT activities for both sexes and depots (r values 0.58-0.91) and between these storage factors and palmitate storage rates into TAG (r values 0.55-0.90). We conclude that: 1) total GPAT activity decreases as a function of adipocyte size; 2) GPAT1 can account for over half of adipose GPAT activity in hypertrophic obesity; and 3) ACS, GPAT, and DGAT are coordinately regulated.
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Affiliation(s)
| | - Liang Chen
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota; Guang'anmen Hospital, Beijing, China
| | - Elisabeth Oberschneider
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota; Department for Internal Medicine, Triemli Hospital, Zürich, Switzerland
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20
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Adipose tissue fatty acid storage factors: effects of depot, sex and fat cell size. Int J Obes (Lond) 2015; 39:884-7. [PMID: 25640767 PMCID: PMC4464947 DOI: 10.1038/ijo.2015.10] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Revised: 01/02/2015] [Accepted: 01/18/2015] [Indexed: 02/01/2023]
Abstract
Background/Objectives Patterns of postabsorptive adipose tissue fatty acid storage correlate with sex-specific body fat distribution. Some proteins and enzymes participating in this pathway include CD36 (facilitated transport), acyl-CoA synthetases (ACS; the first step in fat metabolism), and diacylglycerol acetyl-transferase (DGAT; the final step of triglyceride synthesis). Our goal was to better define CD36, ACS and DGAT in relation to sex, subcutaneous fat depots, and adipocyte size. Subjects/Methods Data was collected from studies conducted at Mayo Clinic between 2004 and 2012. Abdominal and femoral subcutaneous fat biopsy samples must have been collected in the postabsorptive state from healthy males and premenopausal females. Body composition was measured with DXA and abdominal CT scans. Adipocyte size (microscopy), CD36 protein content (ELISA), and ACS and DGAT enzyme activities were measured. Data are presented as medians; 25th:75th quartiles. Results Males (n=60) and females (n=78) did not differ by age (37;28:46 yr), BMI (28.4;24.6:32.1 kg/m2), or abdominal (0.60;0.45:0.83 μg/cell) and femoral adipocyte size (0.76;0.60:0.94 μg/cell). Femoral ACS and DGAT were greater in females than males when expressed per mg lipid (ACS: 73 vs. 55 pmol/mg lipid/min; DGAT: 5.5 vs. 4.0 pmol/ mg lipid/min; p<0.0001 for both) and per 1000 adipocytes (ACS: 59 vs. 39 pmol/1000adipocytes/min; DGAT: 4.3 vs. 3.1 pmol/1000adipocytes/min; p≤0.0003 for both). There were no differences in abdominal fat storage factors between sexes. ACS and DGAT decreased as a function of adipocyte size (p<0.0001 for both). The decrease in ACS was greater in males and abdominal subcutaneous fat. There were no sex differences in CD36 in either fat depot, nor did it vary across adipocyte size. Conclusions Facilitated transport of fatty acids by CD36 under postabsorptive conditions would not be different in those with large vs. small adipocytes in either depot of both sexes. However, intracellular trafficking of fatty acids to triglyceride storage by ACS and DGAT may be less efficient in larger adipocytes.
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21
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Fernández-Galilea M, Pérez-Matute P, Prieto-Hontoria PL, Sáinz N, López-Yoldi M, Houssier M, Martínez JA, Langin D, Moreno-Aliaga MJ. α-lipoic acid reduces fatty acid esterification and lipogenesis in adipocytes from overweight/obese subjects. Obesity (Silver Spring) 2014; 22:2210-5. [PMID: 25045030 DOI: 10.1002/oby.20846] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 06/25/2014] [Accepted: 07/01/2014] [Indexed: 01/09/2023]
Abstract
OBJECTIVE α-Lipoic acid (α-LA) is a natural occurring antioxidant with beneficial effects on obesity. The aim of this study was to investigate the putative effects of α-LA on triglyceride accumulation and lipogenesis in subcutaneous adipocytes from overweight/obese subjects and to determine the potential mechanisms involved. METHODS Fully differentiated human subcutaneous adipocytes were treated with α-LA (100 and 250 µM) during 24 h for studying triglyceride content, de novo lipogenesis, and levels of key lipogenic enzymes. The involvement of AMP-activated protein kinase (AMPK) activation was also evaluated. RESULTS α-LA down-regulated triglyceride content by inhibiting fatty acid esterification and de novo lipogenesis. These effects were mediated by reduction in fatty acid synthase (FAS), stearoyl-coenzyme A desaturase 1, and diacylglycerol O-acyltransferase 1 protein levels. Interestingly, α-LA increased AMPK and acetyl CoA carboxylase phosphorylation, while the presence of the AMPK inhibitor Compound C reversed the inhibition observed on FAS protein levels. CONCLUSIONS α-LA down-regulates key lipogenic enzymes, inhibiting lipogenesis and reducing triglyceride accumulation through the activation of AMPK signaling pathway in human subcutaneous adipocytes from overweight/obese subjects.
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Affiliation(s)
- Marta Fernández-Galilea
- Department of Nutrition, Food Science and Physiology, University of Navarra, Pamplona, Spain
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22
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Sahini N, Borlak J. Recent insights into the molecular pathophysiology of lipid droplet formation in hepatocytes. Prog Lipid Res 2014; 54:86-112. [PMID: 24607340 DOI: 10.1016/j.plipres.2014.02.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 02/17/2014] [Accepted: 02/21/2014] [Indexed: 12/11/2022]
Abstract
Triacyglycerols are a major energy reserve of the body and are normally stored in adipose tissue as lipid droplets (LDs). The liver, however, stores energy as glycogen and digested triglycerides in the form of fatty acids. In stressed condition such as obesity, imbalanced nutrition and drug induced liver injury hepatocytes accumulate excess lipids in the form of LDs whose prolonged storage leads to disease conditions most notably non-alcoholic fatty liver disease (NAFLD). Fatty liver disease has become a major health burden with more than 90% of obese, nearly 70% of overweight and about 25% of normal weight patients being affected. Notably, research in recent years has shown LD as highly dynamic organelles for maintaining lipid homeostasis through fat storage, protein sorting and other molecular events studied in adipocytes and other cells of living organisms. This review focuses on the molecular events of LD formation in hepatocytes and the importance of cross talk between different cell types and their signalling in NAFLD as to provide a perspective on molecular mechanisms as well as possibilities for different therapeutic intervention strategies.
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Affiliation(s)
- Nishika Sahini
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany
| | - Jürgen Borlak
- Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany.
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23
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Côté JA, Nadeau M, Leboeuf M, Blackburn L, Tchernof A. Adipose tissue diacylglycerol acyltransferase activity and blood lipoprotein triglyceride enrichment in women with abdominal obesity. Atherosclerosis 2014; 233:172-7. [PMID: 24529140 DOI: 10.1016/j.atherosclerosis.2013.12.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 11/26/2013] [Accepted: 12/11/2013] [Indexed: 01/31/2023]
Abstract
UNLABELLED Previous studies have suggested altered triglyceride (TG) storage in patients with abdominal obesity and blood lipid disorders. OBJECTIVE We hypothesized that women with abdominal obesity and a dysmetabolic profile have low DGAT activity in their abdominal fat compartments. METHODS Paired omental (OM) and subcutaneous (SC) adipose tissue samples were obtained surgically from 39 women undergoing abdominal hysterectomies. Body composition and fat distribution were measured by dual energy x-ray absorptiometry and computed tomography. DGAT activity was measured by acylation of sn-l,2-diacylglycerol with [(14)C] oleoyl-CoA in microsomal fractions isolated from whole adipose tissue homogenates. DGAT activity was calculated on the basis of picomoles (pmol) TG synthesized in the assay per min per mg lipid, per μg protein or per 1000 cells. RESULTS No depot differences were found when DGAT activity was reported per μg microsomal protein or per 1000 cells. DGAT activity in either depot was not associated with adipocyte diameters and blood lipid profile variables. DGAT activity per mg lipid was higher in OM than in abdominal SC adipose tissue (0.43 ± 0.20 vs. 0.34 ± 0.18 pmol/min/mg lipid, p < 0.05). OM DGAT activity was negatively correlated with OM adipocyte diameter and visceral adipose tissue area (r = -0.43, p < 0.01 and r = -0.38, p < 0.05 respectively). Plasma total, LDL and HDL TG levels were negatively associated with OM DGAT activity independent of total body fat mass (r = -0.39, p < 0.05, r = -0.46, p < 0.001 and r = -0.40, p < 0.05 respectively). CONCLUSION A defect in adipose tissue DGAT activity is predictive of adiposity and blood lipoprotein TG enrichment only when considering activity per tissue lipid mass.
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Affiliation(s)
- Julie Anne Côté
- Endocrinology and Nephrology, Laval University Medical Research Center, Quebec, Canada; Department of Nutrition, Laval University, Quebec, Canada
| | - Mélanie Nadeau
- Endocrinology and Nephrology, Laval University Medical Research Center, Quebec, Canada; Department of Nutrition, Laval University, Quebec, Canada
| | - Mathieu Leboeuf
- Gynecology Unit, Laval University Medical Research Center, Quebec, Canada
| | - Line Blackburn
- Gynecology Unit, Laval University Medical Research Center, Quebec, Canada
| | - André Tchernof
- Endocrinology and Nephrology, Laval University Medical Research Center, Quebec, Canada; Department of Nutrition, Laval University, Quebec, Canada.
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Chatterjee TK, Aronow BJ, Tong WS, Manka D, Tang Y, Bogdanov VY, Unruh D, Blomkalns AL, Piegore MG, Weintraub DS, Rudich SM, Kuhel DG, Hui DY, Weintraub NL. Human coronary artery perivascular adipocytes overexpress genes responsible for regulating vascular morphology, inflammation, and hemostasis. Physiol Genomics 2013; 45:697-709. [PMID: 23737535 DOI: 10.1152/physiolgenomics.00042.2013] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inflammatory cross talk between perivascular adipose tissue and the blood vessel wall has been proposed to contribute to the pathogenesis of atherosclerosis. We previously reported that human perivascular (PV) adipocytes exhibit a proinflammatory phenotype and less adipogenic differentiation than do subcutaneous (SQ) adipocytes. To gain a global view of the genomic basis of biologic differences between PV and SQ adipocytes, we performed genome-wide expression analyses to identify differentially expressed genes between adipocytes derived from human SQ vs. PV adipose tissues. Although >90% of well-expressed genes were similarly regulated, we identified a signature of 307 differentially expressed genes that were highly enriched for functions associated with the regulation of angiogenesis, vascular morphology, inflammation, and blood clotting. Of the 156 PV upregulated genes, 59 associate with angiogenesis, vascular biology, or inflammation, noteworthy of which include TNFRSF11B (osteoprotegerin), PLAT, TGFB1, THBS2, HIF1A, GATA6, and SERPINE1. Of 166 PV downregulated genes, 21 associated with vascular biology and inflammation, including ANGPT1, ANGPTL1, and VEGFC. Consistent with the emergent hypothesis that PV adipocytes differentially regulate angiogenesis and inflammation, cell culture-derived adipocyte-conditioned media from PV adipocytes strongly enhanced endothelial cell tubulogenesis and monocyte migration compared with media from SQ adipocytes. These findings demonstrate that PV adipocytes have the potential to significantly modulate vascular inflammatory crosstalk in the setting of atherosclerosis by their ability to signal to both endothelial and inflammatory cells.
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Affiliation(s)
- Tapan K Chatterjee
- Department of Internal Medicine, University of Cincinnati, Ohio 45267, USA.
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Abstract
Increases in weight have been associated with corresponding increases in insulin resistance in postmenopausal women. Although estrogen has significant impact on body fat and body fat distribution, the cellular mechanisms that influence this process are not yet known. We measured adipose tissue fatty acid (FA) storage and FA storage factors in 12 premenopausal and 11 postmenopausal women matched for age and body composition. Postmenopausal women had lower postprandial FA oxidation (indirect calorimetry), greater meal FA, and direct free FA (FFA) storage than premenopausal women, including two-fold greater meal FA storage in the femoral depot. The fed/fasted activities of adipose tissue lipoprotein lipase were not significantly different between premenopausal and postmenopausal women. In contrast, adipocyte acyl-CoA synthetase and diacylglycerol acyltransferase activities in postmenopausal women were significantly upregulated and were positively correlated with direct FFA storage rates. These findings suggest that the propensity for subcutaneous adipose tissue FA storage is increased in postmenopausal women, more so from changes in adipocyte FA storage factors than from adipose tissue lipoprotein lipase activity. Our results suggest that female sex steroids, most likely estrogen, have important effects on adipose tissue FA storage and FA oxidation that could promote fat gain in postmenopausal women.
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Affiliation(s)
- Sylvia Santosa
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
- Department of Exercise Science, Concordia University, Montreal, Quebec, Canada
| | - Michael D. Jensen
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
- Corresponding author: Michael D. Jensen,
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Wronska A, Kmiec Z. Structural and biochemical characteristics of various white adipose tissue depots. Acta Physiol (Oxf) 2012; 205:194-208. [PMID: 22226221 DOI: 10.1111/j.1748-1716.2012.02409.x] [Citation(s) in RCA: 240] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 09/29/2011] [Accepted: 01/02/2012] [Indexed: 12/11/2022]
Abstract
It is now widely accepted that white adipose tissue (WAT) is not merely a fuel storage organ, but also a key component of metabolic homoeostatic mechanisms. Apart from its major role in lipid and glucose metabolism, adipose tissue is also involved in a wide array of other biological processes. The hormones and adipokines, as well as other biologically active agents released from fat cells, affect many physiological and pathological processes. WAT is neither uniform nor inflexible because it undergoes constant remodelling, adapting the size and number of adipocytes to changes in nutrients' availability and hormonal milieu. Fat depots from different areas of the body display distinct structural and functional properties and have disparate roles in pathology. The two major types of WAT are visceral fat, localized within the abdominal cavity and mediastinum, and subcutaneous fat in the hypodermis. Visceral obesity correlates with increased risk of insulin resistance and cardiovascular diseases, while increase of subcutaneous fat is associated with favourable plasma lipid profiles. Visceral adipocytes show higher lipogenic and lipolytic activities and produce more pro-inflammatory cytokines, while subcutaneous adipocytes are the main source of leptin and adiponectin. Moreover, adipose tissue associated with skeletal muscles (intramyocellular and intermuscular fat) and with the epicardium is believed to provide fuels for skeletal and cardiac muscle contraction. However, increased mass of either epicardial or intermuscular adipose tissue correlates with cardiovascular risk, while the presence of the intramyocellular fat is a risk factor for the development of insulin resistance. This review summarizes results of mainly human studies related to the differential characteristics of various WAT depots.
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Affiliation(s)
- A. Wronska
- Department of Histology; Medical Faculty; Medical University of Gdansk; Gdansk; Poland
| | - Z. Kmiec
- Department of Histology; Medical Faculty; Medical University of Gdansk; Gdansk; Poland
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27
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Suagee JK, Corl BA. An explant based-method for differentiating adipocytes from equine adipose tissue. Equine Vet J 2012; 45:114-6. [PMID: 22607277 DOI: 10.1111/j.2042-3306.2012.00581.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Culturing adipocytes enables fine control of experimental conditions and helps minimise animal use. This report describes an explant-based method for isolating stromal-vascular cells from equine adipose tissue that enables use of small amounts of tissue. Subcutaneous and mesenteric adipose tissues were harvested post mortem and stromal-vascular cells grown from explants, prior to testing the capacity of several differentiation media to induce lipid droplet formation and increase transcript abundance of adipocyte markers. Inclusion of rosiglitazone at 1 and 5 µmol/l concentrations, along with other media components, induced differentiation of cultured equine stromal-vascular cells derived from subcutaneous and mesenteric adipose tissues.
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Affiliation(s)
- J K Suagee
- Department of Dairy Science, Virginia Tech, Blacksburg, Virginia, USA
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28
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Fox CS, Liu Y, White CC, Feitosa M, Smith AV, Heard-Costa N, Lohman K, Johnson AD, Foster MC, Greenawalt DM, Griffin P, Ding J, Newman AB, Tylavsky F, Miljkovic I, Kritchevsky SB, Launer L, Garcia M, Eiriksdottir G, Carr JJ, Gudnason V, Harris TB, Cupples LA, Borecki IB. Genome-wide association for abdominal subcutaneous and visceral adipose reveals a novel locus for visceral fat in women. PLoS Genet 2012; 8:e1002695. [PMID: 22589738 PMCID: PMC3349734 DOI: 10.1371/journal.pgen.1002695] [Citation(s) in RCA: 205] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Accepted: 03/20/2012] [Indexed: 01/08/2023] Open
Abstract
Body fat distribution, particularly centralized obesity, is associated with metabolic risk above and beyond total adiposity. We performed genome-wide association of abdominal adipose depots quantified using computed tomography (CT) to uncover novel loci for body fat distribution among participants of European ancestry. Subcutaneous and visceral fat were quantified in 5,560 women and 4,997 men from 4 population-based studies. Genome-wide genotyping was performed using standard arrays and imputed to ~2.5 million Hapmap SNPs. Each study performed a genome-wide association analysis of subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), VAT adjusted for body mass index, and VAT/SAT ratio (a metric of the propensity to store fat viscerally as compared to subcutaneously) in the overall sample and in women and men separately. A weighted z-score meta-analysis was conducted. For the VAT/SAT ratio, our most significant p-value was rs11118316 at LYPLAL1 gene (p = 3.1 × 10E-09), previously identified in association with waist-hip ratio. For SAT, the most significant SNP was in the FTO gene (p = 5.9 × 10E-08). Given the known gender differences in body fat distribution, we performed sex-specific analyses. Our most significant finding was for VAT in women, rs1659258 near THNSL2 (p = 1.6 × 10-08), but not men (p = 0.75). Validation of this SNP in the GIANT consortium data demonstrated a similar sex-specific pattern, with observed significance in women (p = 0.006) but not men (p = 0.24) for BMI and waist circumference (p = 0.04 [women], p = 0.49 [men]). Finally, we interrogated our data for the 14 recently published loci for body fat distribution (measured by waist-hip ratio adjusted for BMI); associations were observed at 7 of these loci. In contrast, we observed associations at only 7/32 loci previously identified in association with BMI; the majority of overlap was observed with SAT. Genome-wide association for visceral and subcutaneous fat revealed a SNP for VAT in women. More refined phenotypes for body composition and fat distribution can detect new loci not previously uncovered in large-scale GWAS of anthropometric traits.
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Affiliation(s)
- Caroline S. Fox
- Framingham Heart Study, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Center for Population Studies, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Division of Endocrinology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yongmei Liu
- Department of Epidemiology and Prevention, Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Charles C. White
- Framingham Heart Study, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, United States of America
| | - Mary Feitosa
- Division of Statistical Genomics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Albert V. Smith
- Icelandic Heart Association, Research Institute, Kopavogur, Iceland
- University of Iceland, Reykjavik, Iceland
| | - Nancy Heard-Costa
- Framingham Heart Study, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, United States of America
| | - Kurt Lohman
- Department of Epidemiology and Prevention, Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | | | | | | | - Andrew D. Johnson
- Framingham Heart Study, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Center for Population Studies, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
| | - Meredith C. Foster
- Framingham Heart Study, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Center for Population Studies, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
| | | | - Paula Griffin
- Framingham Heart Study, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, United States of America
| | - Jinghong Ding
- Department of Internal Medicine/Geriatrics, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Anne B. Newman
- Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Fran Tylavsky
- Department of Preventive Medicine, University of Tennessee, Memphis, Tennessee, United States of America
| | - Iva Miljkovic
- Center for Aging and Population Health, Department of Epidemiology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Stephen B. Kritchevsky
- Department of Internal Medicine/Geriatrics, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Lenore Launer
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Melissa Garcia
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | | | - J. Jeffrey Carr
- Departments of Radiologic Sciences, Internal Medicine-Cardiology, and Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States of America
| | - Vilmunder Gudnason
- Icelandic Heart Association, Research Institute, Kopavogur, Iceland
- University of Iceland, Reykjavik, Iceland
| | - Tamara B. Harris
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, United States of America
| | - L. Adrienne Cupples
- Framingham Heart Study, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Framingham, Massachusetts, United States of America
- Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts, United States of America
| | - Ingrid B. Borecki
- Division of Statistical Genomics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
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Rogers C, Moukdar F, McGee MA, Davis B, Buehrer BM, Daniel KW, Collins S, Barakat H, Robidoux J. EGF receptor (ERBB1) abundance in adipose tissue is reduced in insulin-resistant and type 2 diabetic women. J Clin Endocrinol Metab 2012; 97:E329-40. [PMID: 22238402 DOI: 10.1210/jc.2011-1033] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
CONTEXT Indications of adipose tissue dysfunction correlate with systemic insulin resistance and type 2 diabetes. It has been suggested that a defect in adipose tissue turnover may be involved in the development of these disorders. Whether this dysfunction causes or exacerbates systemic insulin resistance is not fully understood. OBJECTIVES, PARTICIPANTS, AND MEASURES: We tested whether the expression of members of the mitogenic ErbB family was reduced in adipose tissue of insulin-resistant individuals and whether ErbB1 and ErbB2 were involved in adipogenesis. Thirty-two women covering a wide range of body mass index values and insulin sensitivity participated in the cross-sectional portion of this study. We also studied preadipocytes isolated from 12 insulin-sensitive individuals to evaluate the impact of ErbB1 or ErbB2 inhibition on adipogenesis in vitro. For this purpose, we measured phospho-ErbB1 and phospho-ErbB2 levels using ELISA and the expression of peroxisome proliferator-activated receptor γ (PPARγ) and PPARγ-regulated genes by real-time PCR. RESULTS Among the ErbB family members, only ErbB1 expression was correlated with insulin sensitivity. Additionally, ErbB1 levels correlated positively with PPARγ and several PPARγ-regulated genes including acyl-coenzyme A synthetase long-chain family member 1 (ACSL1), adiponectin, adipose tissue triacylglycerol lipase (ATGL), diacylglycerol acyl transferase 1 (DGAT1), glycerol-3-phosphate dehydrogenase 1 (GPD1), and lipoprotein lipase (LPL), but negatively with CD36 and fatty acid-binding protein 4 (FABP4). In preadipocyte culture, ErbB1, but not ErbB2, inhibition was associated with a reduction in the expression of all the above-mentioned genes. CONCLUSIONS These findings demonstrate a key role for ErbB1 in adipogenesis and suggest that lower ErbB1 protein abundance may lead to adipose tissue dysfunction.
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Affiliation(s)
- Carlyle Rogers
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, North Carolina 27834, USA
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Santosa S, Jensen MD. Effects of male hypogonadism on regional adipose tissue fatty acid storage and lipogenic proteins. PLoS One 2012; 7:e31473. [PMID: 22363653 PMCID: PMC3282778 DOI: 10.1371/journal.pone.0031473] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 01/11/2012] [Indexed: 11/18/2022] Open
Abstract
Testosterone has long been known to affect body fat distribution, although the underlying mechanisms remain elusive. We investigated the effects of chronic hypogonadism in men on adipose tissue fatty acid (FA) storage and FA storage factors. Twelve men with chronic hypogonadism and 13 control men matched for age and body composition: 1) underwent measures of body composition with dual energy x-ray absorptiometry and an abdominal CT scan; 2) consumed an experimental meal containing [(3)H]triolein to determine the fate of meal FA (biopsy-measured adipose storage vs. oxidation); 3) received infusions of [U-(13)C]palmitate and [1-(14)C]palmitate to measure rates of direct free (F)FA storage (adipose biopsies). Adipose tissue lipoprotein lipase, acyl-CoA synthetase (ACS), and diacylglycerol acetyl-transferase (DGAT) activities, as well as, CD36 content were measured to understand the mechanism by which alterations in fat storage occur in response to testosterone deficiency. Results of the study showed that hypogonadal men stored a greater proportion of both dietary FA and FFA in lower body subcutaneous fat than did eugonadal men (both p<0.05). Femoral adipose tissue ACS activity was significantly greater in hypogonadal than eugonadal men, whereas CD36 and DGAT were not different between the two groups. The relationships between these proteins and FA storage varied somewhat between the two groups. We conclude that chronic effects of testosterone deficiency has effects on leg adipose tissue ACS activity which may relate to greater lower body FA storage. These results provide further insight into the role of androgens in body fat distribution and adipose tissue metabolism in humans.
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Affiliation(s)
- Sylvia Santosa
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Exercise Science, Concordia University, Montreal, Canada
| | - Michael D. Jensen
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota, United States of America
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31
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Koutsari C, Mundi MS, Ali AH, Jensen MD. Storage rates of circulating free fatty acid into adipose tissue during eating or walking in humans. Diabetes 2012; 61:329-38. [PMID: 22228715 PMCID: PMC3266422 DOI: 10.2337/db11-0748] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We measured subcutaneous adipose tissue free fatty acid (FFA) storage rates in postprandial and walking conditions to better understand the contributions of this pathway to body fat distribution. Palmitate tracers were infused intravenously and fat biopsies collected to measure palmitate storage in upper- (UBSQ) and lower-body subcutaneous (LBSQ) fat in 41 (17 men) and 40 (16 men) volunteers under postprandial and under postabsorptive walking conditions, respectively. Postprandial palmitate storage was greater in women than men in UBSQ (0.50±0.25 vs. 0.33±0.37 μmol⋅kg fat(-1)⋅min(-1); P=0.007) and LBSQ fat (0.37±0.25 vs. 0.22±0.20 μmol⋅kg fat(-1)⋅min(-1); P=0.005); storage rates were significantly greater in UBSQ than LBSQ fat in both sexes. During walking, UBSQ palmitate storage did not differ between sexes, whereas LBSQ storage was greater in women than men (0.40±0.22 vs. 0.25±0.15 μmol⋅kg fat(-1)⋅min(-1); P=0.01). In women only, walking palmitate storage was significantly greater in LBSQ than UBSQ fat. Adipocyte CD36 and diacylglycerol acyltransferase (DGAT) correlated with LBSQ palmitate storage in the postprandial and walking condition, respectively. We conclude that UBSQ fat is the preferred postprandial FFA storage depot for both sexes, whereas walking favors storage in LBSQ fat in women. Transmembrane transport (CD36) and esterification into triglycerides (DGAT) may be rate-limiting steps for LBSQ FFA storage during feeding and exercise.
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32
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Auguet T, Quintero Y, Terra X, Martínez S, Lucas A, Pellitero S, Aguilar C, Hernández M, del Castillo D, Richart C. Upregulation of lipocalin 2 in adipose tissues of severely obese women: positive relationship with proinflammatory cytokines. Obesity (Silver Spring) 2011; 19:2295-300. [PMID: 21455126 DOI: 10.1038/oby.2011.61] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Because the role of lipocalin 2 (LCN2) in morbid obesity is still not well defined, the aim of this study was to evaluate the circulating levels and the expression of LCN2 in visceral (VAT) and subcutaneous adipose tissue (SAT) in severely obese (SO) women. We also analyzed its relationship with inflammatory cytokines in the same subjects. The study comprised 90 white women, 39 of whom were lean controls (BMI ≤25 kg/m(2)) and 51 SO (BMI ≥40 kg/m(2)). Both circulating and adipose tissue levels of LCN2 were quantified by enzyme-linked immunosorbent assays. LCN2 mRNA levels from VAT and SAT were assessed by real-time reverse transcriptase-PCR (n = 60). LCN2 serum levels were significantly higher in the SO women than in the lean controls (P = 0.042), and were found to be strongly correlated with tumor necrosis factor receptor I (TNFR1) circulating levels. In the SO cohort, LCN2 serum levels were also associated with higher BMI values, but not with the homeostasis model assessments of insulin resistance (HOMA2-IR). LCN2 mRNA expression was markedly higher in SO women than in lean women in both VAT (P = 0.043) and SAT (P = 0.031). In SAT, LCN2 was negatively correlated with adiponectin and adiponectin receptor-2 expression, and positively with interleukin-6 (IL-6) expression. A strong positive correlation was also found between LCN2 expression and the mean diameter of adipocytes in VAT. Our results revealed that the circulating level of LCN2 is associated with obesity and BMI. LCN2 mRNA is over-expressed in adipose tissue from SO subjects. Finally, the expression of LCN2 is strongly related to an expression profile of proinflammatory cytokines but not to insulin resistance in nondiabetic SO women.
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Affiliation(s)
- Teresa Auguet
- Servei Medicina Interna, Hospital Universitari Joan XXIII Tarragona, Tarragona, Spain
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Ali AH, Koutsari C, Mundi M, Stegall MD, Heimbach JK, Taler SJ, Nygren J, Thorell A, Bogachus LD, Turcotte LP, Bernlohr D, Jensen MD. Free fatty acid storage in human visceral and subcutaneous adipose tissue: role of adipocyte proteins. Diabetes 2011; 60:2300-7. [PMID: 21810594 PMCID: PMC3161316 DOI: 10.2337/db11-0219] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE Because direct adipose tissue free fatty acid (FFA) storage may contribute to body fat distribution, we measured FFA (palmitate) storage rates and fatty acid (FA) storage enzymes/proteins in omental and abdominal subcutaneous fat. RESEARCH DESIGN AND METHODS Elective surgery patients received a bolus of [1-(14)C]palmitate followed by omental and abdominal subcutaneous fat biopsies to measure direct FFA storage. Long chain acyl-CoA synthetase (ACS) and diacylglycerol acyltransferase activities, CD36, fatty acid-binding protein, and fatty acid transport protein 1 were measured. RESULTS Palmitate tracer storage (dpm/g adipose lipid) and calculated palmitate storage rates were greater in omental than abdominal subcutaneous fat in women (1.2 ± 0.8 vs. 0.7 ± 0.4 μmol · kg adipose lipid(-1) · min(-1), P = 0.005) and men (0.7 ± 0.2 vs. 0.2 ± 0.1, P < 0.001), and both were greater in women than men (P < 0.0001). Abdominal subcutaneous adipose tissue palmitate storage rates correlated with ACS activity (women: r = 0.66, P = 0.001; men: r = 0.70, P = 0.007); in men, CD36 was also independently related to palmitate storage rates. The content/activity of FA storage enzymes/proteins in omental fat was dramatically lower in those with more visceral fat. In women, only omental palmitate storage rates were correlated (r = 0.54, P = 0.03) with ACS activity. CONCLUSIONS Some adipocyte FA storage factors correlate with direct FFA storage, but sex differences in this process in visceral fat do not account for sex differences in visceral fatness. The reduced storage proteins in those with greater visceral fat suggest that the storage factors we measured are not a predominant cause of visceral adipose tissue accumulation.
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Affiliation(s)
- Asem H. Ali
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
- National Institute of Diabetes and Digestive and Kidney Diseases & National Institute of Child Health and Human Development, Bethesda, Maryland
| | | | - Manpreet Mundi
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Mark D. Stegall
- Department of Surgery, Division of Transplantation Surgery and the William J. von Liebig Transplant Center, Mayo Clinic, Rochester, Minnesota
| | - Julie K. Heimbach
- Department of Surgery, Division of Transplantation Surgery and the William J. von Liebig Transplant Center, Mayo Clinic, Rochester, Minnesota
| | - Sandra J. Taler
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota
| | - Jonas Nygren
- Department of Surgery, Ersta Hospital and Karolinska Institutet, Department of Clinical Sciences, Danderyds Hospital, Stockholm, Sweden
| | - Anders Thorell
- Department of Surgery, Ersta Hospital and Karolinska Institutet, Department of Clinical Sciences, Danderyds Hospital, Stockholm, Sweden
| | - Lindsey D. Bogachus
- Department of Biological Sciences, College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Lorraine P. Turcotte
- Department of Biological Sciences, College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - David Bernlohr
- Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Michael D. Jensen
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
- Corresponding author: Michael D. Jensen,
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Koutsari C, Ali AH, Mundi MS, Jensen MD. Storage of circulating free fatty acid in adipose tissue of postabsorptive humans: quantitative measures and implications for body fat distribution. Diabetes 2011; 60:2032-40. [PMID: 21659500 PMCID: PMC3142075 DOI: 10.2337/db11-0154] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Preferential upper-body fat gain, a typical male pattern, is associated with a greater cardiometabolic risk. Regional differences in lipolysis and meal fat storage cannot explain sex differences in body fat distribution. We examined the potential role of the novel free fatty acid (FFA) storage pathway in determining body fat distribution in postabsorptive humans and whether adipocyte lipogenic proteins (CD36, acyl-CoA synthetases, and diacylglycerol acyltransferase) predict differences in FFA storage. RESEARCH DESIGN AND METHODS Rates of postabsorptive FFA (palmitate) storage into upper-body subcutaneous (UBSQ) and lower-body subcutaneous (LBSQ) fat were measured in 28 men and 53 premenopausal women. Stable and radiolabeled palmitate tracers were intravenously infused followed by subcutaneous fat biopsies. Body composition was assessed with a combination of dual-energy X-ray absorptiometry and computed tomography. RESULTS Women had greater FFA (palmitate) storage than men in both UBSQ (0.37 ± 0.15 vs. 0.27 ± 0.18 μmol · kg(-1) · min(-1), P = 0.0001) and LBSQ (0.42 ± 0.19 vs. 0.22 ± 0.11 μmol · kg(-1) · min(-1), P < 0.0001) fat. Palmitate storage rates were significantly greater in LBSQ than UBSQ fat in women, whereas the opposite was true in men. Plasma palmitate concentration positively predicted palmitate storage in both depots and sexes. Adipocyte CD36 content predicted UBSQ palmitate storage and sex-predicted storage in LBSQ fat. Palmitate storage rates per kilogram fat did not decrease as a function of fat mass, whereas lipolysis did. CONCLUSIONS The FFA storage pathway, which had remained undetected in postabsorptive humans until recently, can have considerable, long-term, and sex-specific effects on body fat distribution. It can also offer a way of protecting the body from excessive circulating FFA in obesity.
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Sex differences during the course of diet-induced obesity in mice: adipose tissue expandability and glycemic control. Int J Obes (Lond) 2011; 36:262-72. [PMID: 21540832 DOI: 10.1038/ijo.2011.87] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
OBJECTIVE Adverse effects of obesity on glucose homeostasis are linked to low-grade adipose tissue inflammation and accumulation of lipids in non-adipose tissues. The goal of this study was to evaluate the role of adipose tissue plasticity in a less severe deterioration of glucose homeostasis in females compared with males during the course of high-fat (HF) feeding in mice. DESIGN Mice of the C57BL/6N strain were fed either a chow or obesogenic HF diet for up to 35 weeks after weaning. Metabolic markers and hormones in plasma, glucose homeostasis, adipocyte size and inflammatory status of gonadal (gWAT) and subcutaneous (scWAT) adipose depots and liver steatosis were evaluated at 15 and 35 weeks of HF feeding. RESULTS HF-fed males were heavier than females until week ∼20, after which the body weights stabilized at a similar level (55-58 g) in both sexes. Greater weight gain and fat accumulation in females were associated with larger adipocytes in gWAT and scWAT at week 35. Although adipose tissue macrophage infiltration was in general less frequent in scWAT, it was reduced in both fat depots of female as compared with male mice; however, the expression of inflammatory markers in gWAT was similar in both sexes at week 35. In females, later onset of the impairment of glucose homeostasis and better insulin sensitivity were associated with higher plasma levels of adiponectin (weeks 0, 15 and 35) and reduced hepatosteatosis (weeks 15 and 35). CONCLUSIONS Compared with males, female mice demonstrate increased capacity for adipocyte enlargement in response to a long-term HF feeding, which is associated with reduced adipose tissue macrophage infiltration and lower fat deposition in the liver, and with better insulin sensitivity. Our data suggest that adipose tissue expandability linked to adiponectin secretion might have a role in the sex differences observed in obesity-associated metabolic disorders.
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