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Risi R, Vidal-Puig A, Bidault G. An adipocentric perspective of pancreatic lipotoxicity in diabetes pathogenesis. J Endocrinol 2024; 262:e230313. [PMID: 38642584 PMCID: PMC11227041 DOI: 10.1530/joe-23-0313] [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: 09/30/2023] [Accepted: 04/16/2024] [Indexed: 04/22/2024]
Abstract
Obesity and diabetes represent two increasing and invalidating public health issues that often coexist. It is acknowledged that fat mass excess predisposes to insulin resistance and type 2 diabetes mellitus (T2D), with the increasing incidence of the two diseases significantly associated. Moreover, emerging evidence suggests that obesity might also accelerate the appearance of type 1 diabetes (T1D), which is now a relatively frequent comorbidity in patients with obesity. It is a common clinical finding that not all patients with obesity will develop diabetes at the same level of adiposity, with gender, genetic, and ethnic factors playing an important role in defining the timing of diabetes appearance. The adipose tissue (AT) expandability hypothesis explains this paradigm, indicating that the individual capacity to appropriately store energy surplus in the form of fat within the AT determines and prevents the toxic deposition of lipids in other organs, such as the pancreas. Thus, we posit that when the maximal storing capacity of AT is exceeded, individuals will develop T2D. In this review, we provide insight into mechanisms by which the AT controls pancreas lipid content and homeostasis in case of obesity to offer an adipocentric perspective of pancreatic lipotoxicity in the pathogenesis of diabetes. Moreover, we suggest that improving AT function is a valid therapeutic approach to fighting obesity-associated complications including diabetes.
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Affiliation(s)
- Renata Risi
- Department of Experimental Medicine, Sapienza University of Rome, Sapienza University of Rome, Rome, Italy
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Antonio Vidal-Puig
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- Cambridge University Nanjing Centre of Technology and Innovation, Nanjing, P. R. China
- Centro de Investigacion Principe Felipe, Valencia, Spain
| | - Guillaume Bidault
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
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2
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Liu H, Niu T, Qiu G, Cui S, Zhang D. Taurine promotes insulin synthesis by enhancing Isl-1 expression through miR-7a/RAF1/ERK1/2 pathway. In Vitro Cell Dev Biol Anim 2024; 60:23-35. [PMID: 38117455 DOI: 10.1007/s11626-023-00835-6] [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: 07/13/2023] [Accepted: 11/04/2023] [Indexed: 12/21/2023]
Abstract
It has been well established that the circulating taurine affects the insulin synthesis in pancreatic islet β-cells, whereas miR-7a and LIM-homeodomain transcription factor Isl-1 are important intracellular factors regulating insulin transcription and synthesis. However, it still remains unknown whether taurine regulates insulin synthesis by affecting miR-7a and/or Isl-1 expressions in mouse pancreatic islet β-cells. The present study was thus proposed to identify the effects of taurine on the expressions of miR-7a and/or Isl-1 and their relations to insulin synthesis in mouse pancreatic islet β-cells by using miR-7a2 knockout (KO) and taurine transporter (TauT) KO mouse models and the related in vitro experiments. The results demonstrated that taurine supplement significantly decreased the pancreas miR-7a expression, but sharply upregulated the pancreas Isl-1 and insulin expressions, and serum insulin levels. However, the enhanced effects of taurine on Isl-1 expression and insulin synthesis were mitigated in the TauT KO and miR-7a2 KO mice. In addition, our results confirmed that taurine markedly increased pancreas RAF1 and ERK1/2 expressions. Collectively, the present study firstly demonstrates that taurine regulates insulin synthesis through TauT/miR-7a/RAF1/ERK1/2/Isl-1 signaling pathway, which are crucial for our understanding the mechanisms of taurine affecting insulin synthesis, and also potential for establishing the therapeutic strategies for diabetes and the diseases related to metabolism.
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Affiliation(s)
- Hui Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Tongjuan Niu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Guobin Qiu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Sheng Cui
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, Jiangsu, People's Republic of China
| | - Di Zhang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.
- Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou, 225009, Jiangsu, People's Republic of China.
- Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, 225009, Jiangsu, People's Republic of China.
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Ohnewein B, Shomanova Z, Paar V, Topf A, Jirak P, Fiedler L, Granitz C, Van Almsick V, Semo D, Zagidullin N, Dieplinger AM, Sindermann J, Reinecke H, Hoppe UC, Pistulli R, Motloch LJ. Effects of Angiotensin Receptor-Neprilysin Inhibitors (ARNIs) on the Glucose and Fat Metabolism Biomarkers Leptin and Fructosamine. J Clin Med 2023; 12:3083. [PMID: 37176525 PMCID: PMC10179018 DOI: 10.3390/jcm12093083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/17/2023] [Accepted: 04/19/2023] [Indexed: 05/15/2023] Open
Abstract
(1) Background: Heart failure with reduced ejection fraction (HFrEF) remains a major health burden. Angiotensin-Receptor-Neprilysin-Inhibitors (ARNIs) are an established HFrEF therapy which increases natriuretic peptide levels by inhibiting neprilysin. Leptin is a lipid metabolism parameter, which is also involved in glucose metabolism and is suggested to correlate with HF burden. While the hormone also seems to interact with neprilysin, potential associations with ARNI therapy have not been investigated yet. (2) Methods: To study this issue, we measured levels of leptin and fructosamine in consecutive 72 HFrEF patients before initiation of ARNI therapy and 3-6 months after initiation of therapy in two European centers. Biomarker levels were correlated with clinical parameters including ejection fraction, LVEF, and NYHA class. (3) Results: During a follow-up of up to 6 months, clinical parameters improved significantly (LVEF: 30.2 ± 7.8% to 37.6 ± 10.0%, (p < 0.001) and a significant improvement of the mean NYHA class with initial 32 patients in NYHA III or IV and 8 patients in NYHA class III/IV during the follow up (p < 0.001). The initial NT-proBNP levels of 2251.5 ± 2566.8 pg/mL significantly improved to 1416.7 ± 2145 pg/mL, p = 0.008) during follow up. ARNI therapy was also associated with an increase in leptin levels (17.5 ± 23.4 µg/L to 22.9 ± 29.3, p < 0.001) and furthermore, affected glucose metabolism indicated by elevation of fructosamine values (333.9 ± 156.8 µmol/L to 454.8 ± 197.8 µmol/L, p = 0.013). (4) Conclusion: while in the early phase of therapy, ARNI promotes clinical improvement of HFrEF, and it also seems to affect fat and glucose parameters, indicating significant metabolic implications of this therapy regime.
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Affiliation(s)
- Bernhard Ohnewein
- Department for Internal Medicine II, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Zornitsa Shomanova
- Department of Cardiology I, Coronary and Peripheral Vascular Disease, Heart Failure, University Hospital Muenster, 48149 Muenster, Germany (R.P.)
| | - Vera Paar
- Department for Internal Medicine II, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Albert Topf
- Department for Internal Medicine II, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Peter Jirak
- Department for Internal Medicine II, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Lukas Fiedler
- Department of Internal Medicine, Cardiology, Nephrology and Intensive Care Medicine, Hospital Wiener Neustadt, 2700 Wiener Neustadt, Austria
| | - Christina Granitz
- Department for Internal Medicine II, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Vincent Van Almsick
- Department of Cardiology I, Coronary and Peripheral Vascular Disease, Heart Failure, University Hospital Muenster, 48149 Muenster, Germany (R.P.)
| | - Dilvin Semo
- Department of Cardiology I, Coronary and Peripheral Vascular Disease, Heart Failure, University Hospital Muenster, 48149 Muenster, Germany (R.P.)
| | - Naufal Zagidullin
- Department of Internal Diseases, Bashkir State Medical University, Lenin str., 3, 450008 Ufa, Russia
| | - Anna-Maria Dieplinger
- Institute for Nursing Science and Practice, Paracelsus Medical University, 5020 Salzburg, Austria
- Medical Faculty, Johannes Kepler University Linz, 4040 Linz, Austria
| | - Juergen Sindermann
- Department of Cardiology I, Coronary and Peripheral Vascular Disease, Heart Failure, University Hospital Muenster, 48149 Muenster, Germany (R.P.)
| | - Holger Reinecke
- Department of Cardiology I, Coronary and Peripheral Vascular Disease, Heart Failure, University Hospital Muenster, 48149 Muenster, Germany (R.P.)
| | - Uta C. Hoppe
- Department for Internal Medicine II, Paracelsus Medical University, 5020 Salzburg, Austria
| | - Rudin Pistulli
- Department of Cardiology I, Coronary and Peripheral Vascular Disease, Heart Failure, University Hospital Muenster, 48149 Muenster, Germany (R.P.)
| | - Lukas J. Motloch
- Department for Internal Medicine II, Paracelsus Medical University, 5020 Salzburg, Austria
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Peters A, Sprengell M, Kubera B. The principle of 'brain energy on demand' and its predictive power for stress, sleep, stroke, obesity and diabetes. Neurosci Biobehav Rev 2022; 141:104847. [PMID: 36067964 DOI: 10.1016/j.neubiorev.2022.104847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 08/10/2022] [Accepted: 08/26/2022] [Indexed: 12/01/2022]
Abstract
Does the brain actively draw energy from the body when needed? There are different schools of thought regarding energy metabolism. In this study, the various theoretical models are classified into one of two categories: (1) conceptualizations of the brain as being purely passively supplied, which we call 'P-models,' and (2) models understanding the brain as not only passively receiving energy but also actively procuring energy for itself on demand, which we call 'A-models.' One prominent example of such theories making use of an A-model is the selfish-brain theory. The ability to make predictions was compared between the A- and P-models. A-models were able to predict and coherently explain all data examined, which included stress, sleep, caloric restriction, stroke, type-1-diabetes mellitus, obesity, and type-2-diabetes, whereas the predictions of P-models failed in most cases. The strength of the evidence supporting A-models is based on the coherence of accurate predictions across a spectrum of metabolic states. The theory test conducted here speaks to a brain that pulls its energy from the body on-demand.
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Affiliation(s)
- Achim Peters
- Medical Clinic 1, Center of Brain, Behavior and Metabolism, University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
| | - Marie Sprengell
- Medical Clinic 1, Center of Brain, Behavior and Metabolism, University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany
| | - Britta Kubera
- Medical Clinic 1, Center of Brain, Behavior and Metabolism, University of Lübeck, Ratzeburger Allee 160, D-23538 Lübeck, Germany
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5
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Xu S, Ye B, Li J, Dou Y, Yu Y, Feng Y, Wang L, Wan DCC, Rong X. Astragalus mongholicus powder, a traditional Chinese medicine formula ameliorate type 2 diabetes by regulating adipoinsular axis in diabetic mice. Front Pharmacol 2022; 13:973927. [PMID: 36046814 PMCID: PMC9420938 DOI: 10.3389/fphar.2022.973927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/20/2022] [Indexed: 11/13/2022] Open
Abstract
The global morbidity of obesity and type 2 diabetes mellitus (T2DM) has dramatically increased. Insulin resistance is the most important pathogenesis and therapeutic target of T2DM. The traditional Chinese medicine formula Astragalus mongholicus powder (APF), consists of Astragalus mongholicus Bunge [Fabaceae], Pueraria montana (Lour.) Merr. [Fabaceae], and Morus alba L. [Moraceae] has a long history to be used to treat diabetes in ancient China. This work aims to investigate the effects of APF on diabetic mice and its underlying mechanism. Diabetic mice were induced by High-fat-diet (HFD) and streptozotocin (STZ). The body weight of mice and their plasma levels of glucose, insulin, leptin and lipids were examined. Reverse transcription-polymerase chain reaction, histology, and Western blot analysis were performed to validate the effects of APF on diabetic mice and investigate the underlying mechanism. APF reduced hyperglycemia, hyperinsulinemia, and hyerleptinemia and attenuate the progression of obesity and non-alcoholic fatty liver disease (NAFLD). However, these effects disappeared in leptin deficient ob/ob diabetic mice and STZ-induced insulin deficient type 1 diabetic mice. Destruction of either these hormones would abolish the therapeutic effects of APF. In addition, APF inhibited the protein expression of PTP1B suppressing insulin–leptin sensitivity, the gluconeogenic gene PEPCK, and the adipogenic gene FAS. Therefore, insulin–leptin sensitivity was normalized, and the gluconeogenic and adipogenic genes were suppressed. In conclusion, APF attenuated obesity, NAFLD, and T2DM by regulating the balance of adipoinsular axis in STZ + HFD induced T2DM mice.
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Affiliation(s)
- Siyuan Xu
- Key Laboratory of Glucolipid Metabolic Disorder, Guangdong TCM Key Laboratory for Metabolic Diseases, Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Ministry of Education of China, Institute of Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China
| | - Bixian Ye
- Department of Nursing, Medical College of Jiaying University, Meizhou, China
| | - Jinlei Li
- School of Chinese Meteria Medica, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yonghui Dou
- School of Chinese Meteria Medica, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Yuying Yu
- Key Laboratory of Glucolipid Metabolic Disorder, Guangdong TCM Key Laboratory for Metabolic Diseases, Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Ministry of Education of China, Institute of Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China
| | - Yifan Feng
- Key Laboratory of Glucolipid Metabolic Disorder, Guangdong TCM Key Laboratory for Metabolic Diseases, Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Ministry of Education of China, Institute of Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China
| | - Lexun Wang
- Key Laboratory of Glucolipid Metabolic Disorder, Guangdong TCM Key Laboratory for Metabolic Diseases, Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Ministry of Education of China, Institute of Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China
| | - David Chi-Cheong Wan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Xianglu Rong
- Key Laboratory of Glucolipid Metabolic Disorder, Guangdong TCM Key Laboratory for Metabolic Diseases, Guangdong Metabolic Diseases Research Center of Integrated Chinese and Western Medicine, Ministry of Education of China, Institute of Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China
- *Correspondence: Xianglu Rong,
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Reiterer M, Gilani A, Lo JC. Pancreatic Islets as a Target of Adipokines. Compr Physiol 2022; 12:4039-4065. [PMID: 35950650 DOI: 10.1002/cphy.c210044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Rising rates of obesity are intricately tied to the type 2 diabetes epidemic. The adipose tissues can play a central role in protection against or triggering metabolic diseases through the secretion of adipokines. Many adipokines may improve peripheral insulin sensitivity through a variety of mechanisms, thereby indirectly reducing the strain on beta cells and thus improving their viability and functionality. Such effects will not be the focus of this article. Rather, we will focus on adipocyte-secreted molecules that have a direct effect on pancreatic islets. By their nature, adipokines represent potential druggable targets that can reach the islets and improve beta-cell function or preserve beta cells in the face of metabolic stress. © 2022 American Physiological Society. Compr Physiol 12:1-27, 2022.
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Affiliation(s)
- Moritz Reiterer
- Division of Cardiology, Department of Medicine, Weill Center for Metabolic Health, Cardiovascular Research Institute, Weill Cornell Medicine, New York, New York, USA
| | - Ankit Gilani
- Division of Cardiology, Department of Medicine, Weill Center for Metabolic Health, Cardiovascular Research Institute, Weill Cornell Medicine, New York, New York, USA
| | - James C Lo
- Division of Cardiology, Department of Medicine, Weill Center for Metabolic Health, Cardiovascular Research Institute, Weill Cornell Medicine, New York, New York, USA
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7
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The Effect of Leptin on the Blood Hormonal Profile (Cortisol, Insulin, Thyroid Hormones) of the Ewe in Acute Inflammation in Two Different Photoperiodical Conditions. Int J Mol Sci 2022; 23:ijms23158109. [PMID: 35897684 PMCID: PMC9331064 DOI: 10.3390/ijms23158109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 01/25/2023] Open
Abstract
As a day animal with sensitivity to inflammation similar to that of humans, the sheep may highly outperform the rodent model in inflammation studies. Additionally, seasonality makes sheep an interesting model in endocrinology research. Although there are studies concerning inflammation’s influence on leptin secretion and vice versa, a ewe model, with its possible ‘long-day leptin resistance’, is still not examined enough. The present study aimed to examine whether leptin may modulate an acute inflammation influence on plasma hormones in two photoperiodical conditions. The experiment was conducted on 48 ewes divided into four groups (control, lipopolysaccharide (LPS), leptin, LPS + leptin) during short and long days. Blood sampling started 1 hour before and continued 3 h after LPS/saline administration for further hormonal analysis. The results showed that the photoperiod is one of the main factors influencing the basal concentrations of several hormones with higher values of leptin, insulin and thyroid hormones during long days. Additionally, the acute inflammation effect on cortisol, insulin and thyroid hormones was photoperiod-dependent. The endotoxemia may also exert an influence on leptin concentration regardless of season. The effects of leptin alone on hormone blood concentrations are rather limited; however, leptin can modulate the LPS influence on insulin or thyroxine in a photoperiod-dependent way.
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8
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Biondi G, Marrano N, Borrelli A, Rella M, Palma G, Calderoni I, Siciliano E, Lops P, Giorgino F, Natalicchio A. Adipose Tissue Secretion Pattern Influences β-Cell Wellness in the Transition from Obesity to Type 2 Diabetes. Int J Mol Sci 2022; 23:ijms23105522. [PMID: 35628332 PMCID: PMC9143684 DOI: 10.3390/ijms23105522] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 05/11/2022] [Accepted: 05/13/2022] [Indexed: 12/10/2022] Open
Abstract
The dysregulation of the β-cell functional mass, which is a reduction in the number of β-cells and their ability to secure adequate insulin secretion, represents a key mechanistic factor leading to the onset of type 2 diabetes (T2D). Obesity is recognised as a leading cause of β-cell loss and dysfunction and a risk factor for T2D. The natural history of β-cell failure in obesity-induced T2D can be divided into three steps: (1) β-cell compensatory hyperplasia and insulin hypersecretion, (2) insulin secretory dysfunction, and (3) loss of β-cell mass. Adipose tissue (AT) secretes many hormones/cytokines (adipokines) and fatty acids that can directly influence β-cell function and viability. As this secretory pattern is altered in obese and diabetic patients, it is expected that the cross-talk between AT and pancreatic β-cells could drive the maintenance of the β-cell integrity under physiological conditions and contribute to the reduction in the β-cell functional mass in a dysmetabolic state. In the current review, we summarise the evidence of the ability of the AT secretome to influence each step of β-cell failure, and attempt to draw a timeline of the alterations in the adipokine secretion pattern in the transition from obesity to T2D that reflects the progressive deterioration of the β-cell functional mass.
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9
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Grasso P. Harnessing the Power of Leptin: The Biochemical Link Connecting Obesity, Diabetes, and Cognitive Decline. Front Aging Neurosci 2022; 14:861350. [PMID: 35527735 PMCID: PMC9072663 DOI: 10.3389/fnagi.2022.861350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/21/2022] [Indexed: 12/02/2022] Open
Abstract
In this review, the current understanding of leptin’s role in energy balance, glycemic regulation, and cognitive function is examined, and its involvement in maintaining the homeostatic “harmony” of these physiologies is explored. The effects of exercise on circulating leptin levels are summarized, and the results of clinical application of leptin to metabolic disease and neurologic dysfunction are reviewed. Finally, pre-clinical evidence is presented which suggests that synthetic peptide leptin mimetics may be useful in resolving not only the leptin resistance associated with common obesity and other elements of metabolic syndrome, but also the peripheral insulin resistance characterizing type 2 diabetes mellitus, and the central insulin resistance associated with certain neurologic deficits in humans.
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Affiliation(s)
- Patricia Grasso
- Department of Medicine, Albany Medical College, Albany, NY, United States
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
- *Correspondence: Patricia Grasso,
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10
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Koethe JR, Moser C, Brown TT, Stein JH, Kelesidis T, Dube M, Currier J, McComsey GA. Adipokines, Weight Gain and Metabolic and Inflammatory Markers After Antiretroviral Therapy Initiation: AIDS Clinical Trials Group (ACTG) A5260s. Clin Infect Dis 2022; 74:857-864. [PMID: 34117756 PMCID: PMC8906713 DOI: 10.1093/cid/ciab542] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND The adipokines leptin and adiponectin, produced primarily by adipose tissue, have diverse endocrine and immunologic effects, and circulating levels reflect adipocyte lipid content, local inflammation, and tissue composition. We assessed relationships between changes in regional fat depots, leptin and adiponectin levels, and metabolic and inflammatory markers over 96 weeks in the AIDS Clinical Trials Group (ACTG) A5260s metabolic substudy of the A5257 randomized trial of tenofovir disoproxil fumarate/emtricitabine plus atazanavir/ritonavir, darunavir/ritonavir, or raltegravir among treatment-naive persons with human immunodeficiency virus (PWH). METHODS Fat depots were measured using dual-energy absorptiometry and abdominal computed tomographic imaging at treatment initiation and 96 weeks later. Serum leptin and adiponectin, homeostatic model assessment of insulin resistance (HOMA-IR), and high-sensitivity C-reactive protein (hsCRP) were measured at the same timepoints. Multivariable regression models assessed relationships between fat depots, adipokines, HOMA-IR, and hsCRP at week 96. RESULTS Two hundred thirty-four participants maintained viral suppression through 96 weeks (90% male, 29% black, median age 36 years). Serum leptin increased over 96 weeks (mean change 22%) while adiponectin did not (mean change 1%), which did not differ by study arm. Greater trunk, limb, and abdominal subcutaneous and visceral fat were associated with higher HOMA-IR and hsCRP at 96 weeks, but serum leptin level was a stronger determinant of these endpoints using a mediation model approach. A similar mediating effect was not observed for adiponectin. CONCLUSIONS Higher circulating leptin is associated with greater HOMA-IR and hsCRP independent of fat depot size, suggesting that greater adipocyte lipid content may contribute to impaired glucose tolerance and systemic inflammation among PWH starting antiretroviral therapy.
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Affiliation(s)
- John R Koethe
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Carlee Moser
- Harvard School of Public Health, Boston, Massachusetts, USA
| | - Todd T Brown
- Johns Hopkins University, Baltimore, Maryland, USA
| | - James H Stein
- University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | | | - Michael Dube
- University of Southern California Keck School of Medicine, Los Angeles, California, USA
| | - Judith Currier
- University of California, Los Angeles, Los Angeles, California, USA
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Abstract
Lipodystrophy syndromes (LS) constitute a group of rare diseases of the adipose tissue, characterized by a complete or selective deficiency of the fat mass. These disorders are associated with important insulin resistance, cardiovascular and metabolic comorbidities that impact patient's survival and quality of life. Management is challenging and includes diet, physical activity, and specific pharmacological treatment of LS-associated comorbidities. Because of a common pathophysiology involving decreased concentration of the adipokine leptin, efforts have been made to develop therapeutic strategies with leptin replacement therapy. Metreleptin, a recombinant human leptin analogue, has been proposed in hypoleptinemic patients since the beginning of 2000's. The treatment leads to an improvement in metabolic parameters, more important in generalized than in partial LS forms. In this review, the current knowledge about the development of the drug, its outcomes in the treatment of lipodystrophic patients as well as the peculiarities of its use will be presented.
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12
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Phoswa WN. The Role of HIV Infection in the Pathophysiology of Gestational Diabetes Mellitus and Hypertensive Disorders of Pregnancy. Front Cardiovasc Med 2021; 8:613930. [PMID: 34055923 PMCID: PMC8149620 DOI: 10.3389/fcvm.2021.613930] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 04/19/2021] [Indexed: 12/21/2022] Open
Abstract
Purpose of the Review: The main objective of this study is to investigate mechanisms associated with gestational diabetes mellitus (GDM) and hypertensive disorders of pregnancy (HDP) in HIV infected pregnant women by looking how placental hormones such as (progesterone and prolactin) and basic haemostatic parameters are regulated in HIV infected pregnancies. Recent Findings: HIV/AIDS are a major global obstetric health burden that lead to increased rate of morbidity and mortality. HIV/AIDS has been associated with the pathophysiology of GDM and HDP. Increased risk of GDM due to highly active antiretroviral therapy (HAART) usage has been reported in HIV infected pregnancies, which causes insulin resistance in both pregnant and non-pregnant individuals. HAART is a medication used for lowering maternal antepartum viral load and pre-exposure and post-exposure prophylaxis of the infant. In pregnant women, HAART induces diabetogenic effect by causing dysregulation of placental hormones such as (progesterone and prolactin) and predispose HIV infected women to GDM. In addition to HIV/AIDS and GDM, Studies have indicated that HIV infection causes haemostatic abnormalities such as hematological disorder, deregulated haematopoiesis process and the coagulation process which results in HDP. Summary: This study will help on improving therapeutic management and understanding of the pathophysiology of GDM and HDP in the absence as well as in the presence of HIV infection by reviewing studies reporting on these mechanism.
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Affiliation(s)
- Wendy N Phoswa
- Department of Life and Consumer Sciences, University of South Africa (UNISA), Science Campus, Florida, South Africa
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13
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Abstract
Leptin is a pluripotent peptide hormone produced mainly by adipocytes, as well as by other tissues such as the stomach. Leptin primarily acts on the central nervous system, particularly the hypothalamus, where this hormone regulates energy homeostasis and neuroendocrine function. Owing to this, disruption of leptin signaling has been linked with numerous pathological conditions. Recent studies have also highlighted the diverse roles of leptin in the digestive system including immune regulation, cell proliferation, tissue healing, and glucose metabolism. Of note, leptin acts differently under physiological and pathological conditions. Here, we review the current knowledge on the functions of leptin and its downstream signaling in the gastrointestinal tract and accessory digestive organs, with an emphasis on its physiological and pathological implications. We also discuss the current therapeutic uses of recombinant leptin, as well as its limitations.
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Affiliation(s)
- Min-Hyun Kim
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Hyeyoung Kim
- Department of Food and Nutrition, College of Human Ecology, Yonsei University, Seoul, Korea
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14
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Billert M, Sassek M, Wojciechowicz T, Jasaszwili M, Strowski MZ, Nowak KW, Skrzypski M. Neuropeptide B stimulates insulin secretion and expression but not proliferation in rat insulin‑producing INS‑1E cells. Mol Med Rep 2019; 20:2030-2038. [PMID: 31257494 DOI: 10.3892/mmr.2019.10415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/24/2019] [Indexed: 11/06/2022] Open
Abstract
Neuropeptide B (NPB) regulates food intake, body weight and energy homeostasis by interacting with NPBW1/NPBW2 in humans and NPBW1 in rodents. NPB and NPBW1 are widely expressed in the central nervous system and peripheral tissues including pancreatic islets. Although previous studies have demonstrated a prominent role for NPB and NPBW1 in controlling glucose and energy homeostasis, it remains unknown as to whether NPB modulates pancreatic β‑cell functions. Therefore, the aim of the present study was to investigate the effects of NPB on insulin expression and secretion in vitro. Furthermore, the role of NPB in the modulation of INS‑1E cell growth, viability and death was examined. Gene expression was assessed by reverse transcription‑quantitative PCR. Cell proliferation and viability were determined by BrdU or MTT tests, respectively. Apoptotic cell death was evaluated by relative quantification histone‑complexed DNA fragments (mono‑and oligonucleosomes). Insulin secretion was studied using an ELISA test. Protein phosphorylation was assessed by western blot analysis. NPB and NPBW1 mRNA was expressed in INS‑1E cells and rat pancreatic islets. In INS‑1E cells, NPB enhanced insulin 1 mRNA expression via an ERK1/2‑dependent mechanism. Furthermore, NPB stimulated insulin secretion from INS‑1E cells and rat pancreatic islets. By contrast, NPB failed to affect INS‑1E cell growth or death. We conclude that NPB may regulate insulin secretion and expression in INS‑1E cells and insulin secretion in rat pancreatic islets.
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Affiliation(s)
- Maria Billert
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Maciej Sassek
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Tatiana Wojciechowicz
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Mariami Jasaszwili
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Mathias Z Strowski
- Department of Hepatology and Gastroenterology, Charité‑University Medicine Berlin, D‑13353 Berlin, Germany
| | - Krzysztof W Nowak
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
| | - Marek Skrzypski
- Department of Animal Physiology and Biochemistry, Poznań University of Life Sciences, 60‑637 Poznań, Poland
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15
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Azhar S, Bittner S, Hu J, Shen WJ, Cortez Y, Hao X, Han L, Lagerstedt JO, Kraemer FB, Johansson JO. Novel ABCA1 peptide agonists with antidiabetic action. Mol Cell Endocrinol 2019; 480:1-11. [PMID: 30290217 PMCID: PMC6626528 DOI: 10.1016/j.mce.2018.09.011] [Citation(s) in RCA: 5] [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] [Received: 07/03/2018] [Revised: 09/19/2018] [Accepted: 09/30/2018] [Indexed: 12/26/2022]
Abstract
Previously, apoE-derived ABCA1 agonist peptides have been shown to possess anti-atherosclerotic and possibly antidiabetic properties. Here we assessed the in vitro and in vivo actions of a second generation of ABCA1 peptide agonists, CS6253 and T6991-2, on glucose homeostasis. The results show that these two peptides improve glucose tolerance in a prediabetic diet-induced obesity mouse model by enhancing insulin secretion. It was further demonstrated that T6991-2 also improved glucose tolerance in leptin-deficient (ob/ob) mice. CS6253 increased insulin secretion both under basal conditions and in response to high glucose stimulation in pancreatic INS-1 β-cells rendered leptin receptor deficient with specific siRNA. Additional in vitro cell studies suggest that the CS6253 agonist attenuates hepatic gluconeogenesis and glucose transport. It also potentiates insulin-stimulated glucose uptake and utilization. These observed anti-diabetic actions suggest additional benefits of the CS6253 and T6991-2 ABCA1 peptide agonists for cardiovascular disease beyond their direct anti-atherosclerosis properties previously described.
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Affiliation(s)
- Salman Azhar
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA; Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Stefanie Bittner
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA
| | - Jie Hu
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA; PCET Division, Aragen Bioscience, 260, Chocrane Circle, Morgan Hill, CA, 94307, USA
| | - Wen-Jun Shen
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA; Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA, 94305, USA.
| | - Yuan Cortez
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA
| | - Xiao Hao
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA; Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA, 94305, USA; Department of Endocrinology, The First Affiliated Hospital of the Medical College of Zhengzhou University, Zhengzhou, China
| | - Lu Han
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA
| | - Jens O Lagerstedt
- Department of Experimental Medical Research, Biomedical Center Floor C13, Tornavagen 10, Lund University, S-221 84, Lund, Sweden
| | - Fredric B Kraemer
- Geriatric Research, Education, and Clinical Center (GRECC), VA Palo Alto Health Care System, Palo Alto, CA, 94304, USA; Division of Endocrinology, Gerontology and Metabolism, Stanford University School of Medicine, Stanford, CA, 94305, USA
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16
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Ferguson D, Blenden M, Hutson I, Du Y, Harris CA. Mouse Embryonic Fibroblasts Protect ob/ob Mice From Obesity and Metabolic Complications. Endocrinology 2018; 159:3275-3286. [PMID: 30085057 PMCID: PMC6109302 DOI: 10.1210/en.2018-00561] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 07/25/2018] [Indexed: 12/22/2022]
Abstract
The global obesity epidemic is fueling alarming rates of diabetes, associated with increased risk of cardiovascular disease and cancer. Leptin is a hormone secreted by adipose tissue that is a key regulator of body weight (BW) and energy expenditure. Leptin-deficient humans and mice are obese, diabetic, and infertile and have hepatic steatosis. Although leptin replacement therapy can alleviate the pathologies seen in leptin-deficient patients and mouse models, treatment is costly and requires daily injections. Because adipocytes are the source of leptin secretion, we investigated whether mouse embryonic fibroblasts (MEFs), capable of forming adipocytes, could be injected into ob/ob mice and prevent the metabolic phenotype seen in these leptin-deficient mice. We performed a single subcutaneous injection of MEFs into leptin-deficient ob/ob mice. The MEF injection formed a single fat pad that is histologically similar to white adipose tissue. The ob/ob mice receiving MEFs (obRs) had significantly lower BW compared with nontreated ob/ob mice, primarily because of decreased adipose tissue mass. Additionally, obR mice had significantly less liver steatosis and greater glucose tolerance and insulin sensitivity. obR mice also manifested lower food intake and greater energy expenditure than ob/ob mice, providing a mechanism underlying their metabolic improvement. Furthermore, obRs have sustained metabolic protection and restoration of fertility. Collectively, our studies show the importance of functional adipocytes in preventing metabolic abnormalities seen in leptin deficiency and point to the possibility of cell-based therapies for the treatment of leptin-deficient states.
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Affiliation(s)
- Daniel Ferguson
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
| | - Mitchell Blenden
- Department of Medical Education, College of Medicine, University of Central Florida, Orlando, Florida
| | - Irina Hutson
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
| | - Yingqiu Du
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
| | - Charles A Harris
- Department of Medicine, Division of Endocrinology, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri
- Department of Medicine, Veterans Affairs St. Louis Healthcare System, John Cochran Division, St. Louis, Missouri
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17
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Rehman K, Akash MSH, Alina Z. Leptin: A new therapeutic target for treatment of diabetes mellitus. J Cell Biochem 2018; 119:5016-5027. [PMID: 29236298 DOI: 10.1002/jcb.26580] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 12/04/2017] [Indexed: 12/15/2022]
Abstract
Leptin is an endogenous protein having 167 amino acids and is derived from adipocytes. It has tertiary structure that resembles with that of the pro-inflammatory cytokines family. The fundamental role of leptin is to maintain the energy homeostasis with the aid of its counter hormone called ghrelin, known as the "hunger hormone." Small quantities of leptin are also present in various tissues like ovary, placenta, pituitary gland, mammary gland, skeletal muscle, stomach, and lymphoid tissue. Expression of leptin is strongly associated with various inflammatory responses and immune system, and plays crucial role in the pathophysiology of obesity and development of diabetes mellitus (DM) and insulin resistance. The metabolic action of leptin is equally important as that of insulin in the pathophysiology of obesity and DM. Thereby, this review article tends to discuss the diverse and complicated role of leptin in the pathogenesis of DM. Furthermore, this article will highlight the signifying role of leptin as a therapeutic target by indicating the targeted treatment of DM through the appropriate understanding of advanced therapeutic approaches using leptin as a treatment strategy for DM.
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Affiliation(s)
- Kanwal Rehman
- Institute of Pharmacy, Physiology and Pharmacology, University of Agriculture, Faisalabad, Pakistan
| | | | - Zunaira Alina
- Institute of Pharmacy, Physiology and Pharmacology, University of Agriculture, Faisalabad, Pakistan
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18
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Dabelea D, Sauder KA. Intrauterine Exposure to Maternal Diabetes and Childhood Obesity. CONTEMPORARY ENDOCRINOLOGY 2018. [DOI: 10.1007/978-3-319-68192-4_13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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19
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Petry SF, Sun LM, Knapp A, Reinl S, Linn T. Distinct Shift in Beta-Cell Glutaredoxin 5 Expression Is Mediated by Hypoxia and Lipotoxicity Both In Vivo and In Vitro. Front Endocrinol (Lausanne) 2018; 9:84. [PMID: 29593651 PMCID: PMC5857561 DOI: 10.3389/fendo.2018.00084] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 02/22/2018] [Indexed: 01/04/2023] Open
Abstract
Histomorphological and functional alterations in pancreatic islet composition directly correlate with hyperglycemia severity. Progressive deterioration of metabolic control in subjects suffering from type 2 diabetes is predominantly caused by impaired beta-cell functionality. The glutaredoxin system is supposed to wield protective properties for beta-cells. Therefore, we sought to identify a correlation between the structural changes observed in diabetic pancreatic islets with altered glutaredoxin 5 expression, in order to determine an underlying mechanism of beta-cell impairment. Islets of db/db mice presenting with uncontrolled diabetes were assessed in terms of morphological structure and insulin, glucagon, and glutaredoxin 5 expression. MIN6 cell function and glutaredoxin 5 expression were analyzed after exposure to oleic acid and hypoxia. Islets of diabese mice were marked by typical remodeling and distinct reduction of, and shifts, in localization of glutaredoxin 5-positive cells. These islets featured decreased glutaredoxin 5 as well as insulin and glucagon content. In beta-cell culture, glutaredoxin 5 protein and mRNA expression were decreased by hypoxia and oleic acid but not by leptin treatment. Our study demonstrates that glutaredoxin 5 expression patterns are distinctively altered in islets of rodents presenting with uncontrolled diabesity. In vitro, reduction of islet-cell glutaredoxin 5 expression was mediated by hypoxia and oleic acid. Thus, glutaredoxin 5-deficiency in islets during diabetes may be caused by lipotoxicity and hypoxia.
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Affiliation(s)
- Sebastian Friedrich Petry
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
- *Correspondence: Sebastian Friedrich Petry,
| | - Lia Mingzhe Sun
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
| | - Anna Knapp
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
| | - Sabrina Reinl
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
| | - Thomas Linn
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University, Giessen, Germany
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20
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 456] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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21
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Skowronski AA, Ravussin Y, Leibel RL, LeDuc CA. Energy homeostasis in leptin deficient Lepob/ob mice. PLoS One 2017; 12:e0189784. [PMID: 29261744 PMCID: PMC5738099 DOI: 10.1371/journal.pone.0189784] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 12/03/2017] [Indexed: 01/28/2023] Open
Abstract
Maintenance of reduced body weight is associated both with reduced energy expenditure per unit metabolic mass and increased hunger in mice and humans. Lowered circulating leptin concentration, due to decreased fat mass, provides a primary signal for this response. However, leptin deficient (Lepob/ob) mice (and leptin receptor deficient Zucker rats) reduce energy expenditure following weight reduction by a necessarily non-leptin dependent mechanisms. To identify these mechanisms, Lepob/ob mice were fed ad libitum (AL group; n = 21) or restricted to 3 kilocalories of chow per day (CR group, n = 21). After losing 20% of initial weight (in approximately 2 weeks), the CR mice were stabilized at 80% of initial body weight for two weeks by titrated refeeding, and then released from food restriction. CR mice conserved energy (-17% below predicted based on body mass and composition during the day; -52% at night); and, when released to ad libitum feeding, CR mice regained fat and lean mass (to AL levels) within 5 weeks. CR mice did so while their ad libitum caloric intake was equal to that of the AL animals. While calorically restricted, the CR mice had a significantly lower respiratory exchange ratio (RER = 0.89) compared to AL (0.94); after release to ad libitum feeding, RER was significantly higher (1.03) than in the AL group (0.93), consistent with their anabolic state. These results confirm that, in congenitally leptin deficient animals, leptin is not required for compensatory reduction in energy expenditure accompanying weight loss, but suggest that the hyperphagia of the weight-reduced state is leptin-dependent.
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Affiliation(s)
- Alicja A. Skowronski
- Institute of Human Nutrition, Columbia University, New York City, New York, United States of America
- Department of Medicine, Columbia University, New York City, New York, United States of America
| | - Yann Ravussin
- Department of Medicine, Columbia University, New York City, New York, United States of America
| | - Rudolph L. Leibel
- Institute of Human Nutrition, Columbia University, New York City, New York, United States of America
- Department of Pediatrics, Columbia University, New York City, New York, United States of America
- Obesity Research Core, Columbia University, New York City, New York, United States of America
| | - Charles A. LeDuc
- Department of Pediatrics, Columbia University, New York City, New York, United States of America
- Obesity Research Core, Columbia University, New York City, New York, United States of America
- * E-mail:
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22
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Molecular regulation of insulin granule biogenesis and exocytosis. Biochem J 2017; 473:2737-56. [PMID: 27621482 DOI: 10.1042/bcj20160291] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 04/19/2016] [Indexed: 12/15/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is a metabolic disorder characterized by hyperglycemia, insulin resistance and hyperinsulinemia in early disease stages but a relative insulin insufficiency in later stages. Insulin, a peptide hormone, is produced in and secreted from pancreatic β-cells following elevated blood glucose levels. Upon its release, insulin induces the removal of excessive exogenous glucose from the bloodstream primarily by stimulating glucose uptake into insulin-dependent tissues as well as promoting hepatic glycogenesis. Given the increasing prevalence of T2DM worldwide, elucidating the underlying mechanisms and identifying the various players involved in the synthesis and exocytosis of insulin from β-cells is of utmost importance. This review summarizes our current understanding of the route insulin takes through the cell after its synthesis in the endoplasmic reticulum as well as our knowledge of the highly elaborate network that controls insulin release from the β-cell. This network harbors potential targets for anti-diabetic drugs and is regulated by signaling cascades from several endocrine systems.
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23
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D'souza AM, Neumann UH, Glavas MM, Kieffer TJ. The glucoregulatory actions of leptin. Mol Metab 2017; 6:1052-1065. [PMID: 28951828 PMCID: PMC5605734 DOI: 10.1016/j.molmet.2017.04.011] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/18/2017] [Accepted: 04/24/2017] [Indexed: 12/28/2022] Open
Abstract
Background The hormone leptin is an important regulator of metabolic homeostasis, able to inhibit food intake and increase energy expenditure. Leptin can also independently lower blood glucose levels, particularly in hyperglycemic models of leptin or insulin deficiency. Despite significant efforts and relevance to diabetes, the mechanisms by which leptin acts to regulate blood glucose levels are not fully understood. Scope of review Here we assess literature relevant to the glucose lowering effects of leptin. Leptin receptors are widely expressed in multiple cell types, and we describe both peripheral and central effects of leptin that may be involved in lowering blood glucose. In addition, we summarize the potential clinical application of leptin in regulating glucose homeostasis. Major conclusions Leptin exerts a plethora of metabolic effects on various tissues including suppressing production of glucagon and corticosterone, increasing glucose uptake, and inhibiting hepatic glucose output. A more in-depth understanding of the mechanisms of the glucose-lowering actions of leptin may reveal new strategies to treat metabolic disorders.
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Affiliation(s)
- Anna M D'souza
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Ursula H Neumann
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Maria M Glavas
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.,Department of Surgery, University of British Columbia, 2350 Health Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada
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24
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Restoration of Lepr in β cells of Lepr null mice does not prevent hyperinsulinemia and hyperglycemia. Mol Metab 2017; 6:585-593. [PMID: 28580288 PMCID: PMC5444109 DOI: 10.1016/j.molmet.2017.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 04/02/2017] [Accepted: 04/04/2017] [Indexed: 11/22/2022] Open
Abstract
Objective The adipose-derived hormone leptin plays an important role in regulating body weight and glucose homeostasis. Leptin receptors are expressed in the central nervous system as well as peripheral tissues involved in regulating glucose homeostasis, including insulin-producing β cells of the pancreas. Previous studies assessing the role of leptin receptors in β cells used Cre-loxP to disrupt the leptin receptor gene (Lepr) in β cells, but variable results were obtained. Furthermore, recombination of Lepr was observed in the hypothalamus or exocrine pancreas, in addition to the β cells, and Lepr in non-β cells may have compensated for the loss of Lepr in β cells, thus making it difficult to assess the direct effects of Lepr in β cells. To determine the significance of Lepr exclusively in β cells, we chose to selectively restore Lepr in β cells of Lepr null mice (LeprloxTB/loxTB). Materials and methods We used a mouse model in which endogenous expression of Lepr was disrupted by a loxP-flanked transcription blocker (LeprloxTB/loxTB), but was restored by Cre recombinase knocked into the Ins1 gene, which is specifically expressed in β cells (Ins1Cre). We bred LeprloxTB/loxTB and Ins1Cre mice to generate LeprloxTB/loxTB and LeprloxTB/loxTBIns1Cre mice, as well as Leprwt/wt and Leprwt/wtIns1Cre littermate mice. Male and female mice were weighed weekly between 6 and 11 weeks of age and fasting blood glucose was measured during this time. Oral glucose was administered to mice aged 7–12 weeks to assess glucose tolerance and insulin secretion. Relative β and α cell area and islet size were also assessed by immunostaining and analysis of pancreas sections of 12–14 week old mice. Results Male and female LeprloxTB/loxTB mice, lacking whole-body expression of Lepr, had a phenotype similar to db/db mice characterized by obesity, hyperinsulinemia, glucose intolerance, and impaired glucose stimulated insulin secretion. Despite restoring Lepr in β cells of LeprloxTB/loxTB mice, fasting insulin levels, blood glucose levels and body weight were comparable between LeprloxTB/loxTBIns1Cre mice and LeprloxTB/loxTB littermates. Furthermore, glucose tolerance and insulin secretion in male and female LeprloxTB/loxTBIns1Cre mice were similar to that observed in LeprloxTB/loxTB mice. Analysis of pancreatic insulin positive area revealed that restoration of Lepr in β cells of LeprloxTB/loxTB mice did not prevent hyperplasia of insulin positive cells nor did it rescue Glut-2 expression. Conclusion Collectively, these data suggest that direct action of leptin on β cells is insufficient to restore normal insulin secretion and glucose tolerance in mice without leptin receptor signaling elsewhere. Restoration of Lepr in β cells of Lepr null mice does not prevent hyperinsulinemia. Leptin receptors in β cells do not inhibit islet hyperplasia. Hyperglycemia and glucose intolerance persist despite restoration of Lepr in β cells of Lepr null mice.
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25
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Hussain MA, Akalestou E, Song WJ. Inter-organ communication and regulation of beta cell function. Diabetologia 2016; 59:659-67. [PMID: 26791990 PMCID: PMC4801104 DOI: 10.1007/s00125-015-3862-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 12/07/2015] [Indexed: 01/18/2023]
Abstract
The physiologically predominant signal for pancreatic beta cells to secrete insulin is glucose. While circulating glucose levels and beta cell glucose metabolism regulate the amount of released insulin, additional signals emanating from other tissues and from neighbouring islet endocrine cells modulate beta cell function. To this end, each individual beta cell can be viewed as a sensor of a multitude of stimuli that are integrated to determine the extent of glucose-dependent insulin release. This review discusses recent advances in our understanding of inter-organ communications that regulate beta cell insulin release in response to elevated glucose levels.
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Affiliation(s)
- Mehboob A Hussain
- Department of Medicine, Johns Hopkins University, 600 N. Wolfe Street, CMSC 10-113, Baltimore, MD, 21287, USA.
- Department of Pediatrics, Johns Hopkins University, 600 N. Wolfe Street, CMSC 10-113, Baltimore, MD, 21287, USA.
- Department of Biological Chemistry, Johns Hopkins University, Baltimore, MD, USA.
| | - Elina Akalestou
- Department of Pediatrics, Johns Hopkins University, 600 N. Wolfe Street, CMSC 10-113, Baltimore, MD, 21287, USA
| | - Woo-Jin Song
- Department of Pediatrics, Johns Hopkins University, 600 N. Wolfe Street, CMSC 10-113, Baltimore, MD, 21287, USA
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26
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Röder PV, Wu B, Liu Y, Han W. Pancreatic regulation of glucose homeostasis. Exp Mol Med 2016; 48:e219. [PMID: 26964835 PMCID: PMC4892884 DOI: 10.1038/emm.2016.6] [Citation(s) in RCA: 467] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 12/03/2015] [Accepted: 12/06/2015] [Indexed: 12/11/2022] Open
Abstract
In order to ensure normal body function, the human body is dependent on a tight control of its blood glucose levels. This is accomplished by a highly sophisticated network of various hormones and neuropeptides released mainly from the brain, pancreas, liver, intestine as well as adipose and muscle tissue. Within this network, the pancreas represents a key player by secreting the blood sugar-lowering hormone insulin and its opponent glucagon. However, disturbances in the interplay of the hormones and peptides involved may lead to metabolic disorders such as type 2 diabetes mellitus (T2DM) whose prevalence, comorbidities and medical costs take on a dramatic scale. Therefore, it is of utmost importance to uncover and understand the mechanisms underlying the various interactions to improve existing anti-diabetic therapies and drugs on the one hand and to develop new therapeutic approaches on the other. This review summarizes the interplay of the pancreas with various other organs and tissues that maintain glucose homeostasis. Furthermore, anti-diabetic drugs and their impact on signaling pathways underlying the network will be discussed.
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Affiliation(s)
- Pia V Röder
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore. E-mail: or
| | - Bingbing Wu
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
| | - Yixian Liu
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
| | - Weiping Han
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Laboratory of Metabolic Medicine, Singapore Bioimaging Consortium, A*STAR, Singapore, Singapore
- Metabolism in Human Diseases Unit, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore 138673, Singapore. E-mail: or
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Wjidan K, Ibrahim E, Caszo B, Gnanou J, Singh H. Dysregulation of Glucose Homeostasis Following Chronic Exogenous Administration of Leptin in Healthy Sprague-Dawley Rats. J Clin Diagn Res 2015; 9:OF06-9. [PMID: 26816939 DOI: 10.7860/jcdr/2015/15594.7003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/14/2015] [Indexed: 12/18/2022]
Abstract
INTRODUCTION Impaired glucose utilization is seen in chronic hyperleptinaemia associated conditions such as obesity and type 2 diabetes mellitus. It is unclear if this impaired glucose utilization is due to the effect of persistent hyperleptinaemia on insulin secretion from the beta cells of pancreas. AIM To examine the effects of chronic leptin administration on plasma glucose regulation in rats. MATERIALS AND METHODS Glucose challenge curves were plotted for male Sprague-Dawley rats treated with either normal saline (Control; n=8) or subcutaneous leptin injection for 42 days (60 μg/kg body weight/day; n=8). Plasma glucose and plasma insulin levels were measured at 0, 5, 10, 15, 20 and 25 minutes after glucose challenege. Skeletal muscle tissue was collected at the end of a glucose challenge for glucose transporter-4 protein content, insulin receptor and glucose transporter-4 mRNA expression. Data were analysed using repeated measures and one-way ANOVA with post-hoc analysis. RESULTS Chronic leptin treatment caused significantly higher fasting insulin level. Post glucose challenge, there was a significant increase in blood glucose levels and insulin level in the leptin treated rats. There was no significant difference in the skeletal muscle glucose transporter-4 content. However, leptin treated rats showed decreased mRNA expression of Insulin Receptor and glucose transporter-4 in the skeletal muscle. CONCLUSION Leptin administration for 42 days caused hyperinsulinaemia and decreased the expression of insulin receptors in insulin sensitive tissues leading to the development of an insulin resistance-like state in the rats.
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Affiliation(s)
- Khalil Wjidan
- Master's Student, Faculty of Medicine, Universiti Teknologi MARA , Sungai Buloh, Malaysia
| | - Effendi Ibrahim
- Lecturer, Faculty of Medicine, Universiti Teknologi MARA , Sungai Buloh, Malaysia
| | - Brinnell Caszo
- Associate Professor, Faculty of Medicine and Defence Health, National Defence University of Malaysia , Kem Sungai Besi, Kuala Lumpur, Malaysia
| | - Justin Gnanou
- Associate Professor, Faculty of Medicine and Defence Health, National Defence University of Malaysia , Kem Sungai Besi, Kuala Lumpur, Malaysia
| | - Harbindarjeet Singh
- Professor, Faculty of Medicine, Universiti Teknologi MARA, Sungai Buloh, Malaysia; I-PerFFORM, Universiti Teknologi MARA , Selayang Campus, Selayang, Kuala Lumpur, Malaysia
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28
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Quiskamp N, Bruin JE, Kieffer TJ. Differentiation of human pluripotent stem cells into β-cells: Potential and challenges. Best Pract Res Clin Endocrinol Metab 2015; 29:833-47. [PMID: 26696513 DOI: 10.1016/j.beem.2015.10.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) hold great potential as the basis for cell-based therapies of degenerative diseases, including diabetes. Current insulin-based therapies for diabetes do not prevent hyperglycaemia or the associated long-term organ damage. While transplantation of pancreatic islets can achieve insulin independence and improved glycemic control, it is limited by donor tissue scarcity, challenges of purifying islets from the pancreas, and the need for immunosuppression to prevent rejection of transplants. Large-scale production of β-cells from stem cells is a promising alternative. Recent years have seen considerable progress in the optimization of in vitro differentiation protocols to direct hESCs/iPSCs into mature insulin-secreting β-cells and clinical trials are now under way to test the safety and efficiency of hESC-derived pancreatic progenitor cells in patients with type 1 diabetes. Here, we discuss key milestones leading up to these trials in addition to recent developments and challenges for hESC/iPSC-based diabetes therapies and disease modeling.
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Affiliation(s)
- Nina Quiskamp
- Laboratory of Molecular and Cellular Medicine, Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.
| | - Jennifer E Bruin
- Laboratory of Molecular and Cellular Medicine, Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada.
| | - Timothy J Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada; Department of Surgery, University of British Columbia, Vancouver, BC, Canada.
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29
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Chimal-Vega B, Paniagua-Castro N, Carrillo Vazquez J, Rosas-Trigueros JL, Zamorano-Carrillo A, Benítez-Cardoza CG. Exploring the structure and conformational landscape of human leptin. A molecular dynamics approach. J Theor Biol 2015; 385:90-101. [PMID: 26342543 DOI: 10.1016/j.jtbi.2015.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 07/21/2015] [Accepted: 08/17/2015] [Indexed: 11/29/2022]
Abstract
Leptin is a hormone that regulates energy homeostasis, inflammation, hematopoiesis and immune response, among other functions (Houseknecht et al., 1998; Zhang et al., 1995; Paz-Filho et al., 2010). To obtain its crystallographic structure, it was necessary to substitute a tryptophan for a glutamic acid at position 100, thus creating a mutant leptin that has been reported to have biological activity comparable to the activity of the wild type but that crystallizes more readily. Here, we report a comparative study of the conformational space of WT and W100E leptin using molecular dynamics simulations performed at 300, 400, and 500 K. We detected differences between the interactions of the two proteins with local and distal effects, resulting in changes in the conformation, accessible surface area, compactness, electrostatic potential and dynamic behavior. Additionally, the series of unfolding events that occur when leptin is subjected to high temperature differs for the two constructs. We observed that both proteins are mostly unstructured after 20 ns of MD simulation at 500 K. However, WT leptin maintains a significant amount of secondary structure in helix α2, while the most stable region of W100E leptin is helix α3. Furthermore, we found that the region between residues 25 and 42 might adopt interconverting secondary structures ranging from α-helices and random coils to β-strand structures. Thus, this region can be considered an intrinsically disordered region. This atomistic description supports our understanding of leptin signaling and consequently might facilitate the use of leptin in treatments for the pathophysiologies in which it is implicated.
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Affiliation(s)
- Brenda Chimal-Vega
- Laboratorio de Investigación Bioquímica y Biofísica Computacional, Doctorado en Ciencias en Biotecnología, ENMH, Instituto Politécnico Nacional, Guillermo Massieu Helguera, México, D.F. 07320, México
| | - Norma Paniagua-Castro
- Departamento de Fisiología, Doctorado en Ciencias en Biotecnología, ENCB, Instituto Politécnico Nacional. Avenida Wilfrido Massieu s/n, Esq. Manuel L. Stampa, Col. Unidad Profesional Adolfo López Mateos, Delegación Gustavo A. Madero, 07738 México, D.F., México
| | - Jonathan Carrillo Vazquez
- Laboratorio de Investigación Bioquímica y Biofísica Computacional, Doctorado en Ciencias en Biotecnología, ENMH, Instituto Politécnico Nacional, Guillermo Massieu Helguera, México, D.F. 07320, México
| | - Jorge L Rosas-Trigueros
- Laboratorio Transdisciplinario de Investigación en Sistemas Evolutivos, SEPI de la ESCOM del Instituto Politécnico Nacional, Juan de Dios Bátiz y Miguel Othón de Mendizábal s/n, México, D.F. 07738, México
| | - Absalom Zamorano-Carrillo
- Laboratorio de Investigación Bioquímica y Biofísica Computacional, Doctorado en Ciencias en Biotecnología, ENMH, Instituto Politécnico Nacional, Guillermo Massieu Helguera, México, D.F. 07320, México
| | - Claudia G Benítez-Cardoza
- Laboratorio de Investigación Bioquímica y Biofísica Computacional, Doctorado en Ciencias en Biotecnología, ENMH, Instituto Politécnico Nacional, Guillermo Massieu Helguera, México, D.F. 07320, México.
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30
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Grosbellet E, Dumont S, Schuster-Klein C, Guardiola-Lemaitre B, Pevet P, Criscuolo F, Challet E. Leptin modulates the daily rhythmicity of blood glucose. Chronobiol Int 2015; 32:637-49. [DOI: 10.3109/07420528.2015.1035440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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31
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Tahergorabi Z, Khazaei M. Leptin and its cardiovascular effects: Focus on angiogenesis. Adv Biomed Res 2015; 4:79. [PMID: 26015905 PMCID: PMC4434486 DOI: 10.4103/2277-9175.156526] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 07/20/2014] [Indexed: 12/24/2022] Open
Abstract
Leptin is an endocrine hormone synthesized by adipocytes. It plays a key role in the energy homeostasis in central and peripheral tissues and has additional roles are attributed to it, such as the regulation of reproduction, immune function, bone homeostasis, and angiogenesis. The plasma concentration of leptin significantly increases in obese individuals. In the present review, we give an introduction concerning leptin, its receptors, signaling pathways, and its effect on cardiovascular system, especially on angiogenesis.
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Affiliation(s)
- Zoya Tahergorabi
- Department of Physiology and Pharmacology, Birjand University of Medical Sciences, Birjand, Iran
| | - Majid Khazaei
- Department of Physiology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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Zhou L, Jang KY, Moon YJ, Wagle S, Kim KM, Lee KB, Park BH, Kim JR. Leptin ameliorates ischemic necrosis of the femoral head in rats with obesity induced by a high-fat diet. Sci Rep 2015; 5:9397. [PMID: 25797953 PMCID: PMC4369691 DOI: 10.1038/srep09397] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 03/03/2015] [Indexed: 02/06/2023] Open
Abstract
Obesity is a risk factor for ischemic necrosis of the femoral head (INFH). The purpose of this study was to determine if leptin treatment of INFH stimulates new bone formation to preserve femoral head shape in rats with diet-induced obesity. Rats were fed a high-fat diet (HFD) or normal chow diet (NCD) for 16 weeks to induce progressive development of obesity. Avascular necrosis of the femoral head (AVN) was surgically induced. Adenovirus-mediated introduction of the leptin gene was by intravenous injection 2 days before surgery-induced AVN. At 6 weeks post-surgery, radiologic and histomorphometric assessments were performed. Leptin signaling in tissues was examined by Western blot. Osteogenic markers were analyzed by real-time RT-PCR. Radiographs showed better preservation of femoral head architecture in the HFD-AVN-Leptin group than the HFD-AVN and HFD-AVN-LacZ groups. Histology and immunohistochemistry revealed the HFD-AVN-Leptin group had significantly increased osteoblastic proliferation and vascularity in infarcted femoral heads compared with the HFD-AVN and HFD-AVN-LacZ groups. Intravenous injection of leptin enhanced serum VEGF levels and activated HIF-1α pathways. Runx 2 and its target genes were significantly upregulated in the HFD-AVN-Leptin group. These results indicate that leptin resistance is important in INFH pathogenesis. Leptin therapy could be a new strategy for INFH.
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Affiliation(s)
- Lu Zhou
- 1] Department of Orthopaedic Surgery, Chonbuk National University Medical School, Research Institute for Endocrine Sciences and Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea [2] Department of Sports Medicine, Taishan Medical University, Shandong, China
| | - Kyu Yun Jang
- Department of Pathology, Chonbuk National University Medical School, Research Institute for Endocrine Sciences and Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea
| | - Young Jae Moon
- Department of Biochemistry, Chonbuk National University Medical School, Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Sajeev Wagle
- Department of Orthopaedic Surgery, Chonbuk National University Medical School, Research Institute for Endocrine Sciences and Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea
| | - Kyoung Min Kim
- Department of Pathology, Chonbuk National University Medical School, Research Institute for Endocrine Sciences and Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea
| | - Kwang Bok Lee
- Department of Orthopaedic Surgery, Chonbuk National University Medical School, Research Institute for Endocrine Sciences and Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea
| | - Byung-Hyun Park
- Department of Biochemistry, Chonbuk National University Medical School, Research Institute for Endocrine Sciences, Jeonju, Republic of Korea
| | - Jung Ryul Kim
- Department of Orthopaedic Surgery, Chonbuk National University Medical School, Research Institute for Endocrine Sciences and Research Institute of Clinical Medicine of Chonbuk National University-Biomedical Research Institute of Chonbuk National University Hospital, Jeonju, Republic of Korea
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Park HK, Ahima RS. Physiology of leptin: energy homeostasis, neuroendocrine function and metabolism. Metabolism 2015; 64:24-34. [PMID: 25199978 PMCID: PMC4267898 DOI: 10.1016/j.metabol.2014.08.004] [Citation(s) in RCA: 390] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/01/2014] [Accepted: 08/08/2014] [Indexed: 12/24/2022]
Abstract
Leptin is secreted by adipose tissue and regulates energy homeostasis, neuroendocrine function, metabolism, immune function and other systems through its effects on the central nervous system and peripheral tissues. Leptin administration has been shown to restore metabolic and neuroendocrine abnormalities in individuals with leptin-deficient states, including hypothalamic amenorrhea and lipoatrophy. In contrast, obese individuals are resistant to leptin. Recombinant leptin is beneficial in patients with congenital leptin deficiency or generalized lipodystrophy. However, further research on molecular mediators of leptin resistance is needed for the development of targeted leptin sensitizing therapies for obesity and related metabolic diseases.
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Affiliation(s)
- Hyeong-Kyu Park
- Department of Internal Medicine, Soonchunhyang University College of Medicine, Seoul, Republic of Korea
| | - Rexford S Ahima
- Division of Endocrinology, Diabetes and Metabolism, and the Institute for Diabetes, Obesity and Metabolism, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
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34
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Kebede MA, Oler AT, Gregg T, Balloon AJ, Johnson A, Mitok K, Rabaglia M, Schueler K, Stapleton D, Thorstenson C, Wrighton L, Floyd BJ, Richards O, Raines S, Eliceiri K, Seidah NG, Rhodes C, Keller MP, Coon JL, Audhya A, Attie AD. SORCS1 is necessary for normal insulin secretory granule biogenesis in metabolically stressed β cells. J Clin Invest 2014; 124:4240-56. [PMID: 25157818 DOI: 10.1172/jci74072] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 07/14/2014] [Indexed: 01/21/2023] Open
Abstract
We previously positionally cloned Sorcs1 as a diabetes quantitative trait locus. Sorcs1 belongs to the Vacuolar protein sorting-10 (Vps10) gene family. In yeast, Vps10 transports enzymes from the trans-Golgi network (TGN) to the vacuole. Whole-body Sorcs1 KO mice, when made obese with the leptin(ob) mutation (ob/ob), developed diabetes. β Cells from these mice had a severe deficiency of secretory granules (SGs) and insulin. Interestingly, a single secretagogue challenge failed to consistently elicit an insulin secretory dysfunction. However, multiple challenges of the Sorcs1 KO ob/ob islets consistently revealed an insulin secretion defect. The luminal domain of SORCS1 (Lum-Sorcs1), when expressed in a β cell line, acted as a dominant-negative, leading to SG and insulin deficiency. Using syncollin-dsRed5TIMER adenovirus, we found that the loss of Sorcs1 function greatly impairs the rapid replenishment of SGs following secretagogue challenge. Chronic exposure of islets from lean Sorcs1 KO mice to high glucose and palmitate depleted insulin content and evoked an insulin secretion defect. Thus, in metabolically stressed mice, Sorcs1 is important for SG replenishment, and under chronic challenge by insulin secretagogues, loss of Sorcs1 leads to diabetes. Overexpression of full-length SORCS1 led to a 2-fold increase in SG content, suggesting that SORCS1 is sufficient to promote SG biogenesis.
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Abstract
The fat‐derived hormone, leptin, is well known to regulate body weight. However, there is now substantial evidence that leptin also plays a primary role in the regulation of glucose homeostasis, independent of actions on food intake, energy expenditure or body weight. As such, leptin might have clinical utility in treating hyperglycemia, particularly in conditions of leptin deficiency, such as lipodystrophy and diabetes mellitus. The mechanisms through which leptin modulates glucose metabolism have not been fully elucidated. Leptin receptors are widely expressed in peripheral tissues, including the endocrine pancreas, liver, skeletal muscle and adipose, and both direct and indirect leptin action on these tissues contributes to the control of glucose homeostasis. Here we review the role of leptin in glucose homeostasis, along with our present understanding of the mechanisms involved. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00203.x, 2012)
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Affiliation(s)
- Heather C Denroche
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Frank K Huynh
- Department of Cellular and Physiological Sciences, The Life Sciences Institute
| | - Timothy J Kieffer
- Department of Cellular and Physiological Sciences, The Life Sciences Institute ; Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
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36
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Alzheimer's disease and type 2 diabetes via chronic inflammatory mechanisms. Saudi J Biol Sci 2014; 22:4-13. [PMID: 25561876 DOI: 10.1016/j.sjbs.2014.05.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 05/13/2014] [Accepted: 05/14/2014] [Indexed: 01/11/2023] Open
Abstract
Recent evidence has indicated that type 2 diabetes mellitus (T2DM) increases the risk of developing Alzheimer's disease (AD). Therefore, it is crucial to investigate the potential common processes that could explain this relation between AD and T2DM. In the recent decades, an abundance of evidence has emerged demonstrating that chronic inflammatory processes may be the major factors contributing to the development and progression of T2DM and AD. In this article, we have discussed the molecular underpinnings of inflammatory process that contribute to the pathogenesis of T2DM and AD and how they are linked to these two diseases. In depth understanding of the inflammatory mechanisms through which AD and T2DM are associated to each other may help the researchers to develop novel and more effective strategies to treat together AD and T2DM. Several treatment options have been identified which spurn the inflammatory processes and discourage the production of inflammatory mediators, thereby preventing or slowing down the onset of T2DM and AD.
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37
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Tudurí E, Denroche HC, Kara JA, Asadi A, Fox JK, Kieffer TJ. Partial ablation of leptin signaling in mouse pancreatic α-cells does not alter either glucose or lipid homeostasis. Am J Physiol Endocrinol Metab 2014; 306:E748-55. [PMID: 24473435 DOI: 10.1152/ajpendo.00681.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The role of glucagon in the pathological condition of diabetes is gaining interest, and it has been recently reported that its action is essential for hyperglycemia to occur. Glucagon levels, which are elevated in some diabetic models, are reduced following leptin therapy. Likewise, hyperglycemia is corrected in type 1 diabetic mice treated with leptin, although the mechanisms have not been fully determined. A direct inhibitory effect of leptin on mouse and human α-cells has been demonstrated at the levels of electrical activity, calcium signaling, and glucagon secretion. In the present study we employed the Cre-loxP strategy to generate Lepr(flox/flox) Gcg-cre mice, which specifically lack leptin receptors in glucagon-secreting α-cells, to determine whether leptin resistance in α-cells contributes to hyperglucagonemia, and also whether leptin action in α-cells is required to improve glycemia in type 1 diabetes with leptin therapy. Immunohistochemical analysis of pancreas sections revealed Cre-mediated recombination in ∼ 43% of the α-cells. We observed that in vivo Lepr(flox/flox) Gcg-cre mice display normal glucose and lipid homeostasis. In addition, leptin administration in streptozotocin-induced diabetic Lepr(flox/flox) Gcg-cre mice restored euglycemia similarly to control mice. These findings suggest that loss of leptin receptor signaling in close to one-half of α-cells does not alter glucose metabolism in vivo, nor is it sufficient to prevent the therapeutic action of leptin in type 1 diabetes.
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MESH Headings
- Animals
- Cells, Cultured
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 1/drug therapy
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Female
- Gene Deletion
- Glucagon-Secreting Cells/metabolism
- Glucose/metabolism
- Homeostasis/genetics
- Leptin/metabolism
- Leptin/therapeutic use
- Lipid Metabolism/genetics
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Signal Transduction/genetics
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Affiliation(s)
- Eva Tudurí
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada; and
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Saeed S, Bech PR, Hafeez T, Alam R, Falchi M, Ghatei MA, Bloom SR, Arslan M, Froguel P. Changes in levels of peripheral hormones controlling appetite are inconsistent with hyperphagia in leptin-deficient subjects. Endocrine 2014; 45:401-8. [PMID: 23824601 DOI: 10.1007/s12020-013-0009-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 06/22/2013] [Indexed: 01/05/2023]
Abstract
Congenital leptin deficiency, a rare genetic disorder due to a homozygous mutation in the leptin gene (LEP), is accompanied by extreme obesity and hyperphagia. A number of gastrointestinal hormones have been shown to critically regulate food intake but their physiological role in hyperphagic response in congenital leptin deficiency has not been elucidated. This study is the first to evaluate the fasting and postprandial profiles of gut-derived hormones in homozygous and heterozygous carriers of LEP mutation. The study subjects from two consanguineous families consisted of five homozygous and eight heterozygous carriers of LEP mutation, c.398delG. Ten wild-type normal-weight subjects served as controls. Fasting and 1-h postprandial plasma ghrelin, glucagon-like peptide (GLP) 1, peptide YY (PYY), leptin and insulin levels were measured by immunoassays. Fasting plasma ghrelin levels in homozygotes remained remarkably unchanged following food consumption (P = 0.33) in contrast to a significant decline in heterozygous (P < 0.03) and normal (P < 0.02) subjects. A significant postprandial increase in PYY was observed in heterozygous (P < 0.02) and control subjects (P < 0.01), but not in the homozygous group (P = 0.22). A postprandial rise in GLP-1 levels was significant (P < 0.02) in all groups. Interestingly, fasting leptin levels in heterozygotes were not significantly different from controls and did not change significantly following meal. Our results demonstrate that gut hormones play little or no physiological role in driving the hyperphagic response of leptin-deficient subjects. In contrast, fasting and postprandial levels of gut hormones in heterozygous mutation carriers were comparable to those of normal-weight controls.
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Affiliation(s)
- Sadia Saeed
- Department of Genomics of Common Disease, Hammersmith Hospital, Imperial College London, Burlington-Danes Building, Du Cane Road, London, W12 0NN, UK
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Muniyappa R, Brown RJ, Mari A, Joseph J, Warren MA, Cochran EK, Skarulis MC, Gorden P. Effects of leptin replacement therapy on pancreatic β-cell function in patients with lipodystrophy. Diabetes Care 2014; 37:1101-7. [PMID: 24496806 PMCID: PMC3964492 DOI: 10.2337/dc13-2040] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Leptin administration is known to directly modulate pancreatic β-cell function in leptin-deficient rodent models. However, human studies examining the effects of leptin administration on β-cell function are lacking. In this study, we examined the effects (16-20 weeks) of leptin replacement on β-cell function in patients with lipodystrophy. RESEARCH DESIGN AND METHODS In a prospective, open-label, currently ongoing study, we studied the effects of leptin replacement on β-cell function in 13 patients with congenital or acquired lipodystrophy. Insulin secretory rate (ISR) was calculated by C-peptide deconvolution from plasma glucose and C-peptide levels measured during oral glucose tolerance tests (OGTTs) performed at baseline and after 16-20 weeks of leptin replacement. β-Cell glucose sensitivity and rate sensitivity were assessed by mathematical modeling of OGTT. RESULTS There was a significant decrease in triglycerides, free fatty acids, and glycosylated hemoglobin levels (A1C) after leptin therapy. Patients with lipodystrophy have high fasting and glucose-stimulated ISR. However, leptin therapy had no significant effect on fasting ISR, total insulin secretion during OGTT, β-cell glucose sensitivity, rate sensitivity, or insulin clearance. CONCLUSIONS In contrast to the suppressive effects of leptin on β-cell function in rodents, 16-20-week treatment with leptin in lipodystrophy patients did not significantly affect insulin secretion or β-cell function in leptin-deficient individuals with lipodystrophy.
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40
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Chen GC, Qin LQ, Ye JK. Leptin levels and risk of type 2 diabetes: gender-specific meta-analysis. Obes Rev 2014; 15:134-42. [PMID: 24102863 DOI: 10.1111/obr.12088] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 08/10/2013] [Accepted: 08/11/2013] [Indexed: 01/08/2023]
Abstract
This meta-analysis aimed to assess the gender-specific differences in the relationship between circulating leptin levels and risk of type 2 diabetes. Published prospective studies that reported the association of leptin levels with risk of type 2 diabetes for a certain gender or those that reported gender-specific associations were considered. Dose-response relationships were assessed by the generalized least squares trend estimation and summary relative risks (RRs) with 95% confidence interval (CI) were computed with the random-effects model. Stratified and sensitivity analyses were also performed to investigate potential sources of heterogeneity. Overall, 11 prospective studies were identified. The summary RR for an increment in leptin levels of 1-log ng mL(-1) was 1.37 (95% CI, 1.13-1.66) for men and 0.96 (95% CI, 0.90-1.03) for women. The differences between genders were statistically significant (P for interaction = 0.006). Subgroup and sensitivity analyses generally confirmed the robustness of these findings. Furthermore, the increased risk in men appeared non-linear, with a tendency to plateau at high levels (P for non-linearity = 0.03). Little evidence of publication bias was found. Collectively, higher leptin levels were found to be associated with elevated risk of type 2 diabetes in men but not in women.
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Affiliation(s)
- G-C Chen
- Ningbo Municipal Center for Disease Control and Prevention, Ningbo, China
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Reporter islets in the eye reveal the plasticity of the endocrine pancreas. Proc Natl Acad Sci U S A 2013; 110:20581-6. [PMID: 24248353 DOI: 10.1073/pnas.1313696110] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The islets of Langerhans constitute the endocrine part of the pancreas and are responsible for maintenance of blood glucose homeostasis. They are deeply embedded in the exocrine pancreas, limiting their accessibility for functional studies. Understanding regulation of function and survival and assessing the clinical outcomes of individual treatment strategies for diabetes requires a monitoring system that continuously reports on the endocrine pancreas. We describe the application of a natural body window that successfully reports on the properties of in situ pancreatic islets. As proof of principle, we transplanted "reporter islets" into the anterior chamber of the eye of leptin-deficient mice. These islets displayed obesity-induced growth and vascularization patterns that were reversed by leptin treatment. Hence, reporter islets serve as optically accessible indicators of islet function in the pancreas, and also reflect the efficacy of specific treatment regimens aimed at regulating islet plasticity in vivo.
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Insulin downregulates the expression of the Ca2+-activated nonselective cation channel TRPM5 in pancreatic islets from leptin-deficient mouse models. Pflugers Arch 2013; 466:611-21. [PMID: 24221356 PMCID: PMC3928505 DOI: 10.1007/s00424-013-1389-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 10/04/2013] [Accepted: 10/17/2013] [Indexed: 11/07/2022]
Abstract
We recently proposed that the transient receptor potential melastatin 5 (TRPM5) cation channel contributes to glucose-induced electrical activity of the β cell and positively influences glucose-induced insulin release and glucose homeostasis. In this study, we investigated Trpm5 expression and function in pancreatic islets from mouse models of type II diabetes. Gene expression analysis revealed a strong reduction of Trpm5 mRNA levels in pancreatic islets of db/db and ob/ob mice. The glucose-induced Ca2+ oscillation pattern in db/db and ob/ob islets mimicked those of Trpm5−/− islets. Leptin treatment of ob/ob mice not only reversed the diabetic phenotype seen in these mice but also upregulated Trpm5 expression. Leptin treatment had no additional effect on Trpm5 expression levels when plasma insulin levels were comparable to those of the vehicle-injected control group. In murine β cell line, MIN6, insulin downregulated TRPM5 expression in a dose-dependent manner, unlike glucose or leptin. In conclusion, our data show that increased plasma insulin levels downregulate TRPM5 expression in pancreatic islets from leptin-deficient mouse models of type 2 diabetes.
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Ye Q, Danzer CF, Fuchs A, Vats D, Wolfrum C, Rudin M. Longitudinal evaluation of hepatic lipid deposition and composition in ob/ob and ob/+ control mice. NMR IN BIOMEDICINE 2013; 26:1079-1088. [PMID: 23355481 DOI: 10.1002/nbm.2921] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2012] [Revised: 11/05/2012] [Accepted: 12/17/2012] [Indexed: 06/01/2023]
Abstract
Obesity is associated with insulin resistance (IR) and hepatosteatosis. Understanding the link between IR and hepatosteatosis could be relevant to chronic clinical outcomes. The objective of this study was to quantitatively assess lipid deposition (fractional lipid mass, fLM) and composition (fraction of polyunsaturated lipids, fPUL and mean chain length, MCL) in livers of ob/ob mice, a genetic model of obesity and mild diabetes, and ob/+ heterozygous control animals in a noninvasive manner using (1) H-MRS at 9.4T. For accurate quantification, intensity values were corrected for differences in T2 values while T1 effects were considered minimal due to the long TR values used. Values of fLM, fPUL and MCL were derived from T2 -corrected signal intensities of lipids and water resonance. Hepatic lipid signals were compared with fasted plasma insulin, glucose and lipid levels. Statistically significant correlations between fPUL and fasting plasma insulin/glucose levels were found in adolescent ob/ob mice. A similar correlation was found between fLM and fasting plasma insulin levels; however, the correlation between fLM and fasting plasma glucose levels was less obvious in adolescent ob/ob mice. These correlations were lost in adult ob/ob mice. The study showed that in adolescent ob/ob mice, there was an obvious link between lipid deposition/composition in the liver and plasma insulin/glucose levels. This correlation was lost in adult animals, probably due to the limited lipid storage capacity of the liver.
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Affiliation(s)
- Qiong Ye
- Institute for Biomedical Engineering, ETH Zürich and University of Zürich, Switzerland
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44
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Tudurí E, Bruin JE, Denroche HC, Fox JK, Johnson JD, Kieffer TJ. Impaired Ca(2+) signaling in β-cells lacking leptin receptors by Cre-loxP recombination. PLoS One 2013; 8:e71075. [PMID: 23936486 PMCID: PMC3731269 DOI: 10.1371/journal.pone.0071075] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 06/30/2013] [Indexed: 11/21/2022] Open
Abstract
Obesity is a major risk factor for diabetes and is typically associated with hyperleptinemia and a state of leptin resistance. The impact of chronically elevated leptin levels on the function of insulin-secreting β-cells has not been elucidated. We previously generated mice lacking leptin signaling in β-cells by using the Cre-loxP strategy and showed that these animals develop increased body weight and adiposity, hyperinsulinemia, impaired glucose-stimulated insulin secretion and insulin resistance. Here, we performed several in vitro studies and observed that β-cells lacking leptin signaling in this model are capable of properly metabolizing glucose, but show impaired intracellular Ca2+ oscillations and lack of synchrony within the islets in response to glucose, display reduced response to tolbutamide and exhibit morphological abnormalities including increased autophagy. Defects in intracellular Ca2+ signaling were observed even in neonatal islets, ruling out the possible contribution of obesity to the β-cell irregularities observed in adults. In parallel, we also detected a disrupted intracellular Ca2+ pattern in response to glucose and tolbutamide in control islets from adult transgenic mice expressing Cre recombinase under the rat insulin promoter, despite these animals being glucose tolerant and secreting normal levels of insulin in response to glucose. This unexpected observation impeded us from discerning the consequences of impaired leptin signaling as opposed to long-term Cre expression in the function of insulin-secreting cells. These findings highlight the need to generate improved Cre-driver mouse models or new tools to induce Cre recombination in β-cells.
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Affiliation(s)
- Eva Tudurí
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jennifer E. Bruin
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Heather C. Denroche
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessica K. Fox
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - James D. Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J. Kieffer
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail:
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45
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Denroche HC, Quong WL, Bruin JE, Tudurí E, Asadi A, Glavas MM, Fox JK, Kieffer TJ. Leptin administration enhances islet transplant performance in diabetic mice. Diabetes 2013; 62:2738-46. [PMID: 23656888 PMCID: PMC3717838 DOI: 10.2337/db12-1684] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Islet transplantation is an effective method to obtain long-term glycemic control for patients with type 1 diabetes, yet its widespread use is limited by an inadequate supply of donor islets. The hormone leptin has profound glucose-lowering and insulin-sensitizing action in type 1 diabetic rodent models. We hypothesized that leptin administration could reduce the dose of transplanted islets required to achieve metabolic control in a mouse model of type 1 diabetes. We first performed a leptin dose-response study in C57Bl/6 mice with streptozotocin (STZ)-induced diabetes to determine a leptin dose insufficient to reverse hyperglycemia. Subsequently, we compared the ability of suboptimal islet transplants of 50 or 125 syngeneic islets to achieve glycemic control in STZ-induced diabetic C57Bl/6 mice treated with or without this dose of leptin. The dose-response study revealed that leptin reverses STZ-induced diabetes in a dose-dependent manner. Supraphysiological leptin levels were necessary to restore euglycemia but simultaneously increased risk of hypoglycemia, and also lost efficacy after 12 days of administration. In contrast, 1 µg/day leptin only modestly reduced blood glucose but maintained efficacy throughout the study duration. We then administered 1 µg/day leptin to diabetic mice that underwent transplantation of 50 or 125 islets. Although these islet doses were insufficient to ameliorate hyperglycemia alone, coadministration of leptin with islet transplantation robustly improved control of glucose and lipid metabolism, without increasing circulating insulin levels. This study reveals that low-dose leptin administration can reduce the number of transplanted islets required to achieve metabolic control in STZ-induced diabetic mice.
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Affiliation(s)
- Heather C. Denroche
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Whitney L. Quong
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jennifer E. Bruin
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eva Tudurí
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Ali Asadi
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Maria M. Glavas
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jessica K. Fox
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Timothy J. Kieffer
- Laboratory of Molecular and Cellular Medicine, Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding author: Timothy J. Kieffer,
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46
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Su Y, Carey LC, Rose JC, Pulgar VM. Antenatal glucocorticoid exposure enhances the inhibition of adrenal steroidogenesis by leptin in a sex-specific fashion. Am J Physiol Endocrinol Metab 2013; 304:E1404-11. [PMID: 23632631 PMCID: PMC3680693 DOI: 10.1152/ajpendo.00013.2013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Antenatal treatment with glucocorticoids (GC) poses long-lasting effects on endocrine and cardiovascular function. Given that leptin attenuates adrenal function and the reported sex differences in plasma leptin concentration, we hypothesized that antenatal GC will affect leptin levels and leptin modulation of adrenal function in a sex-specific manner. Pregnant sheep were randomly given betamethasone or vehicle at 80 days of gestational age, and offspring were allowed to deliver at term. Adrenocortical cells (ADC) were studied from male and female animals at 1.5 yr of age. Plasma leptin was increased 66% in male and 41% in female GC-treated animals (P < 0.05), but adrenal leptin mRNA was increased only in GC-treated males (P < 0.05). Whereas mRNA expression of adrenal leptin receptor isoforms showed sex (Ob-Ra and Ob-Rb) and treatment-dependent (Ob-Rb) differences, protein expression remained unchanged. GC-treated females showed greater plasma cortisol and greater ACTH-stimulated cortisol production (P < 0.05) in ADC. Leptin exerted a greater inhibitory effect on basal and stimulated cortisol by ADC from GC-treated males (P < 0.05), with no differences in females. Similarly, greater inhibitory effects on basal and ACTH-stimulated StAR and ACTH-R mRNA expression by leptin were observed in cells from GC males (P < 0.05), with no changes in females. Persistent effects of antenatal GC on leptin levels and leptin modulation of adrenal function are expressed in a sex-specific manner; males are more sensitive than females to the inhibitory influences of leptin on adrenal function, and this effect appears to be mediated by a greater inhibition of StAR and ACTH-R expression in adrenals of adult GC-treated males.
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Affiliation(s)
- Yixin Su
- Department of Obstetrics and Gynecology
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Kraemer RR, Francois M, Webb ND, Worley JR, Rogers SN, Norman RL, Shah U, Castracane VD. No effect of menstrual cycle phase on glucose and glucoregulatory endocrine responses to prolonged exercise. Eur J Appl Physiol 2013; 113:2401-8. [PMID: 23765198 DOI: 10.1007/s00421-013-2677-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2013] [Accepted: 06/01/2013] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Prolonged exercise requires increased utilization of blood glucose and adjustment of glucoregulatory hormones. Estrogen can reduce hepatic gluconeogenesis which could affect insulin concentrations. Amylin is co-secreted with insulin and controls influx of glucose into the blood. PURPOSE To determine the effect of menstrual cycle stage on glucose, leptin, and pancreatic hormone responses to prolonged (90 min) exercise. METHODS Five healthy, eumenorrheic women (24.6 ± 5.1 years; 67.4 ± 1 kg) were monitored for 3 months to determine menstrual cycle length. Subjects completed a preliminary session to determine exercise workloads and, in a fasted condition, completed two randomized 90-min treadmill exercise trials at 60 % VO2max during the early follicular (EFX) and mid-luteal phase (MLX) of their menstrual cycle. Blood samples were analyzed for glucose, insulin, C-peptide, amylin, glucagon, leptin, and cortisol concentrations at rest (-30 and 0 min), during exercise (18, 36, 54, 72, and 90 min) and after 20 min of recovery. RESULTS No changes in amylin, leptin, or cortisol occurred for EFX and MLX trials. A significant (p < 0.05) time effect occurred for glucose, insulin, and glucagon with reduced insulin across the exercise trial and increases in glucose and glucagon later in the trial, but there were no differences between the EFX and MLX trials. CONCLUSIONS Menstrual cycle stage does not affect glucose, insulin, C-peptide, amylin, glucagon, cortisol, and leptin responses to prolonged exercise; however, the exercise reduces insulin and increases glucose and glucagon concentrations. This is the first study to determine acute effects of exercise on amylin and other glucoregulatory hormone responses in women.
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Affiliation(s)
- Robert R Kraemer
- Department of Kinesiology and Health Studies, Southeastern Louisiana University, SLU10845, Hammond, LA 70402, USA.
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48
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Harris RBS. Direct and indirect effects of leptin on adipocyte metabolism. Biochim Biophys Acta Mol Basis Dis 2013; 1842:414-23. [PMID: 23685313 DOI: 10.1016/j.bbadis.2013.05.009] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/18/2013] [Accepted: 05/06/2013] [Indexed: 12/22/2022]
Abstract
Leptin is hypothesized to function as a negative feedback signal in the regulation of energy balance. It is produced primarily by adipose tissue and circulating concentrations correlate with the size of body fat stores. Administration of exogenous leptin to normal weight, leptin responsive animals inhibits food intake and reduces the size of body fat stores whereas mice that are deficient in either leptin or functional leptin receptors are hyperphagic and obese, consistent with a role for leptin in the control of body weight. This review discusses the effect of leptin on adipocyte metabolism. Because adipocytes express leptin receptors there is the potential for leptin to influence adipocyte metabolism directly. Adipocytes also are insulin responsive and receive sympathetic innervation, therefore leptin can also modify adipocyte metabolism indirectly. Studies published to date suggest that direct activation of adipocyte leptin receptors has little effect on cell metabolism in vivo, but that leptin modifies adipocyte sensitivity to insulin to inhibit lipid accumulation. In vivo administration of leptin leads to a suppression of lipogenesis, an increase in triglyceride hydrolysis and an increase in fatty acid and glucose oxidation. Activation of central leptin receptors also contributes to the development of a catabolic state in adipocytes, but this may vary between different fat depots. Leptin reduces the size of white fat depots by inhibiting cell proliferation both through induction of inhibitory circulating factors and by contributing to sympathetic tone which suppresses adipocyte proliferation. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
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Affiliation(s)
- Ruth B S Harris
- Department of Physiology, Medical College of Georgia, Georgia Regents University, USA.
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Amitani M, Asakawa A, Amitani H, Inui A. The role of leptin in the control of insulin-glucose axis. Front Neurosci 2013; 7:51. [PMID: 23579596 PMCID: PMC3619125 DOI: 10.3389/fnins.2013.00051] [Citation(s) in RCA: 126] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 03/18/2013] [Indexed: 12/21/2022] Open
Abstract
Obesity and diabetes mellitus are great public health concerns throughout the world because of their increasing incidence and prevalence. Leptin, the adipocyte hormone, is well known for its role in the regulation of food intake and energy expenditure. In addition to the regulation of appetite and satiety that recently has attracted much attentions, insight has also been gained into the critical role of leptin in the control of the insulin-glucose axis, peripheral glucose and insulin responsiveness. Since the discovery of leptin, leptin has been taken for its therapeutic potential to obesity and diabetes. Recently, the therapeutic effects of central leptin gene therapy have been reported in insulin-deficient diabetes in obesity animal models such as ob/ob mise, diet-induced obese mice, and insulin-deficient type 1 diabetes mice, and also in patients with inactivating mutations in the leptin gene. Herein, we review the role of leptin in regulating feeding behavior and glucose metabolism and also the therapeutic potential of leptin in obesity and diabetes mellitus.
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Affiliation(s)
- Marie Amitani
- Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences Kagoshima, Japan
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50
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Quercetin Preserves β -Cell Mass and Function in Fructose-Induced Hyperinsulinemia through Modulating Pancreatic Akt/FoxO1 Activation. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:303902. [PMID: 23533474 PMCID: PMC3600179 DOI: 10.1155/2013/303902] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2012] [Revised: 01/26/2013] [Accepted: 01/26/2013] [Indexed: 12/20/2022]
Abstract
Fructose-induced hyperinsulinemia is associated with insulin compensative secretion and predicts the onset of type 2 diabetes. In this study, we investigated the preservation of dietary flavonoid quercetin on pancreatic β-cell mass and function in fructose-treated rats and INS-1 β-cells. Quercetin was confirmed to reduce serum insulin and leptin levels and blockade islet hyperplasia in fructose-fed rats. It also prevented fructose-induced β-cell proliferation and insulin hypersecretion in INS-1 β-cells. High fructose increased forkhead box protein O1 (FoxO1) expressions in vivo and in vitro, which were reversed by quercetin. Quercetin downregulated Akt and FoxO1 phosphorylation in fructose-fed rat islets and increased the nuclear FoxO1 levels in fructose-treated INS-1 β-cells. The elevated Akt phosphorylation in fructose-treated INS-1 β-cells was also restored by quercetin. Additionally, quercetin suppressed the expression of pancreatic and duodenal homeobox 1 (Pdx1) and insulin gene (Ins1 and Ins2) in vivo and in vitro. In fructose-treated INS-1 β-cells, quercetin elevated the reduced janus kinase 2/signal transducers and activators of transcription 3 (Jak2/Stat3) phosphorylation and suppressed the increased suppressor of cytokine signaling 3 (Socs3) expression. These results demonstrate that quercetin protects β-cell mass and function under high-fructose induction through improving leptin signaling and preserving pancreatic Akt/FoxO1 activation.
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