1
|
Ramírez-Vélez R, González-Ruíz K, González-Jiménez E, Schmidt-RioValle J, Correa-Rodríguez M, García-Hermoso A, Palomino-Echeverría S, Izquierdo M. Serum leptin as a mediator of the influence of insulin resistance on hepatic steatosis in youths with excess adiposity. Nutr Metab Cardiovasc Dis 2021; 31:1308-1316. [PMID: 33618924 DOI: 10.1016/j.numecd.2020.12.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND AIMS The relationship between insulin resistance (IR) and hepatic steatosis (fatty liver) is well known; however, the extent to which the satiety hormone leptin acts as a confounder or mediator in this relationship is uncertain. We examined whether the association between IR and hepatic steatosis is mediated by leptin in Colombian adolescents with excess adiposity. METHODS AND RESULTS A total of 122 adolescents (mean age: 13.4 years; 68% girls) participated in the study. We assessed body composition, hepatic steatosis (as defined by the controlled attenuation parameter [CAP]), cardiometabolic risk factors (body mass index, waist circumference, body composition), biochemical variables (leptin, insulin, glucose, lipid profile, cardiometabolic Z-score, transaminases, etc.), and physical fitness (cardiorespiratory fitness and grip strength). Partial correlation, regression, and mediation analyses were conducted using the Barron and Kenny framework. RESULTS Ninety-two youths (75.4%) had IR. Mediation analysis revealed a positive relationship between Homeostasis Model Assessment-IR (HOMA-IR) and CAP (βdir = 3.414, 95% confidence interval [CI]: 1.012 to 5.816, p < 0.001), which was attenuated when leptin was included in the model, thus indicating that leptin mediates this relationship (βind = 1.074, 95% CI: 0.349 to 2.686, p < 0.001). The percentage of the total effect mediated by leptin was 21%. Regarding sex, the mediation effect of leptin remains significant among boys (βind = 0.962, 95% CI: 0.009 to 2.615, p < 0.001), but not in girls (βind = 0.991, 95% CI: 1.263 to 5.483, p = 0.477). CONCLUSIONS The findings are clinically relevant to consider leptin levels as a surrogate marker of insulin sensitivity when assessing youths with excess adiposity and/or suspected Nonalcoholic hepatic steatosis or nonalcoholic fatty liver disease (NAFLD).
Collapse
Affiliation(s)
- Robinson Ramírez-Vélez
- Navarrabiomed, Complejo Hospitalario de Navarra (CHN)-Universidad Pública de Navarra (UPNA), IDISNA, 31008, Pamplona, Spain; CIBER of Frailty and Healthy Aging (CIBERFES), Institute of Health Carlos III, Madrid, Spain.
| | - Katherine González-Ruíz
- Physical Exercise and Sports Research Group, Vice Chancellor for Research, Manuela Beltrán University (UMB), Bogotá, DC, 110231, Colombia.
| | - Emilio González-Jiménez
- Department of Nursing, Health Sciences Faculty, University of Granada, Avda. De la Ilustración 60, 18016, Granada, Spain.
| | - Jacqueline Schmidt-RioValle
- Department of Nursing, Health Sciences Faculty, University of Granada, Avda. De la Ilustración 60, 18016, Granada, Spain.
| | - María Correa-Rodríguez
- Department of Nursing, Health Sciences Faculty, University of Granada, Avda. De la Ilustración 60, 18016, Granada, Spain.
| | - Antonio García-Hermoso
- Navarrabiomed, Complejo Hospitalario de Navarra (CHN)-Universidad Pública de Navarra (UPNA), IDISNA, 31008, Pamplona, Spain; Physical Activity, Sport and Health Sciences Laboratory, University of Santiago de Chile (USACH), Santiago de Chile, 7500618, Chile.
| | - Sara Palomino-Echeverría
- Translational Bioinformatics Unit (TransBio), Navarrabiomed, Complejo Hospitalario de Navarra (CHN)-Universidad Pública de Navarra (UPNA), IDISNA, 31008, Pamplona, Spain.
| | - Mikel Izquierdo
- Navarrabiomed, Complejo Hospitalario de Navarra (CHN)-Universidad Pública de Navarra (UPNA), IDISNA, 31008, Pamplona, Spain; CIBER of Frailty and Healthy Aging (CIBERFES), Institute of Health Carlos III, Madrid, Spain.
| |
Collapse
|
2
|
Yang Y, Xu Y. The central melanocortin system and human obesity. J Mol Cell Biol 2020; 12:785-797. [PMID: 32976556 PMCID: PMC7816681 DOI: 10.1093/jmcb/mjaa048] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/04/2020] [Accepted: 08/14/2020] [Indexed: 12/13/2022] Open
Abstract
The prevalence of obesity and the associated comorbidities highlight the importance of understanding the regulation of energy homeostasis. The central melanocortin system plays a critical role in controlling body weight balance. Melanocortin neurons sense and integrate the neuronal and hormonal signals, and then send regulatory projections, releasing anorexigenic or orexigenic melanocortin neuropeptides, to downstream neurons to regulate the food intake and energy expenditure. This review summarizes the latest progress in our understanding of the role of the melanocortin pathway in energy homeostasis. We also review the advances in the identification of human genetic variants that cause obesity via mechanisms that affect the central melanocortin system, which have provided rational targets for treatment of genetically susceptible patients.
Collapse
Affiliation(s)
- Yongjie Yang
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Yong Xu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| |
Collapse
|
3
|
Gorgisen G, Karatas U, Ates C, Oksuz M, Gulacar IM. Association of IRS1 Gly972Arg and IRS2 Gly1057Asp polymorphisms with gastric cancer in Turkish subjects. Oncol Lett 2020; 20:2016-2020. [PMID: 32724448 DOI: 10.3892/ol.2020.11717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 05/14/2020] [Indexed: 01/14/2023] Open
Abstract
Insulin receptor substrate (IRS) proteins are cytoplasmic adaptors that transmit the signal from the IR and insulin-like growth factor-1 receptor to effector proteins. Overexpression of IRS proteins has been indicated to be linked to cancer development. In addition to their expression profiles, studies have indicated that polymorphisms of IRS1 and IRS2 are also associated with the susceptibility to numerous cancer types. IRS1 Gly972Arg and IRS2 Gly1057Asp are the common variants of these genes. The present study aimed to determine the association of IRS1 Gly972Arg and IRS2 Gly1057Asp polymorphisms with gastric cancer development. The study included 100 patients with gastric cancer and 100 controls. Single-nucleotide polymorphisms were detected by real-time PCR using Taqman assays. The results suggested that in individuals with the IRS1 Gly/Arg genotype, the odds of having gastric cancer was increased by 7.891-fold (95% CI: 3.251-19.154, P<0.001) and in individuals with the IRS1 Arg/Arg genotype, it was increased by 22.716-fold (95% CI: 6.311-81.761, P<0.001) compared with those with the IRS1 Gly/Gly genotype. Although the IRS2 Gly1057Asp genotype analysis suggested that subjects with the Asp/Asp genotype had a 2,311-fold increased odds of having gastric cancer compared to those with the Gly/Gly genotype, the result was not statistically significant (95% CI: 0.800-6.678, P=0.122). The combined effects of the IRS1 and IRS2 variants on gastric cancer were also determined. The results suggested that individuals with Gly/Arg+Gly/Asp and Gly/Arg+Asp/Asp genotypes had a higher odds of having gastric cancer compared to individuals of the Gly/Gly+Gly/Gly genotype (P=0.001 and P=0.027, respectively). In conclusion, the present results suggested that the IRS1 Gly972Arg and IRS2 Gly1057Asp variations may be associated with an increased susceptibility to develop gastric cancer. Further studies with larger sample sizes are required to support the present results and to explore the use of these variations as a biomarker for gastric cancer.
Collapse
Affiliation(s)
- Gokhan Gorgisen
- Department of Medical Biology, Faculty of Medicine, Van Yuzuncu Yil University, Van 65080, Turkey
| | - Ugur Karatas
- Department of Medical Biology, Faculty of Medicine, Van Yuzuncu Yil University, Van 65080, Turkey
| | - Can Ates
- Department of Biostatistics, Faculty of Medicine, Van Yuzuncu Yil University, Van 65080, Turkey
| | - Murat Oksuz
- Department of Gastroenterology, Private Adana Ortadogu Hospital, Adana 67055, Turkey
| | - Ismail Musab Gulacar
- Department of Medical Biology, Faculty of Medicine, Van Yuzuncu Yil University, Van 65080, Turkey
| |
Collapse
|
4
|
Seoane-Collazo P, Martínez-Sánchez N, Milbank E, Contreras C. Incendiary Leptin. Nutrients 2020; 12:nu12020472. [PMID: 32069871 PMCID: PMC7071158 DOI: 10.3390/nu12020472] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 02/06/2020] [Accepted: 02/08/2020] [Indexed: 02/08/2023] Open
Abstract
Leptin is a hormone released by adipose tissue that plays a key role in the control of energy homeostasis through its binding to leptin receptors (LepR), mainly expressed in the hypothalamus. Most scientific evidence points to leptin’s satiating effect being due to its dual capacity to promote the expression of anorexigenic neuropeptides and to reduce orexigenic expression in the hypothalamus. However, it has also been demonstrated that leptin can stimulate (i) thermogenesis in brown adipose tissue (BAT) and (ii) the browning of white adipose tissue (WAT). Since the demonstration of the importance of BAT in humans 10 years ago, its study has aroused great interest, mainly in the improvement of obesity-associated metabolic disorders through the induction of thermogenesis. Consequently, several strategies targeting BAT activation (mainly in rodent models) have demonstrated great potential to improve hyperlipidemias, hepatic steatosis, insulin resistance and weight gain, leading to an overall healthier metabolic profile. Here, we review the potential therapeutic ability of leptin to correct obesity and other metabolic disorders, not only through its satiating effect, but by also utilizing its thermogenic properties.
Collapse
Affiliation(s)
- Patricia Seoane-Collazo
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan
- CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain;
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
- Correspondence: (P.S.-C.); (N.M.-S.); (C.C.); Tel.: +81-298-533-301 (P.S.-C.); +34-913-941-650 (N.M.-S.); +44-01865285890 (C.C.)
| | - Noelia Martínez-Sánchez
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford OX1 3PT, UK
- Correspondence: (P.S.-C.); (N.M.-S.); (C.C.); Tel.: +81-298-533-301 (P.S.-C.); +34-913-941-650 (N.M.-S.); +44-01865285890 (C.C.)
| | - Edward Milbank
- CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain;
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706 Santiago de Compostela, Spain
| | - Cristina Contreras
- Department of Physiology, Pharmacy School, Complutense University of Madrid, 28040 Madrid, Spain
- Correspondence: (P.S.-C.); (N.M.-S.); (C.C.); Tel.: +81-298-533-301 (P.S.-C.); +34-913-941-650 (N.M.-S.); +44-01865285890 (C.C.)
| |
Collapse
|
5
|
Fenerich BA, Fernandes JC, Rodrigues Alves APN, Coelho-Silva JL, Scopim-Ribeiro R, Scheucher PS, Eide CA, Tognon CE, Druker BJ, Rego EM, Machado-Neto JA, Traina F. NT157 has antineoplastic effects and inhibits IRS1/2 and STAT3/5 in JAK2 V617F-positive myeloproliferative neoplasm cells. Signal Transduct Target Ther 2020; 5:5. [PMID: 32296029 PMCID: PMC6978524 DOI: 10.1038/s41392-019-0102-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 11/15/2019] [Accepted: 11/24/2019] [Indexed: 12/25/2022] Open
Abstract
Recent data indicate that IGF1R/IRS signaling is a potential therapeutic target in BCR-ABL1-negative myeloproliferative neoplasms (MPN); in this pathway, IRS2 is involved in the malignant transformation induced by JAK2V617F, and upregulation of IGF1R signaling induces the MPN phenotype. NT157, a synthetic compound designed as an IGF1R-IRS1/2 inhibitor, has been shown to induce antineoplastic effects in solid tumors. Herein, we aimed to characterize the molecular and cellular effects of NT157 in JAK2V617F-positive MPN cell lines (HEL and SET2) and primary patient hematopoietic cells. In JAK2V617F cell lines, NT157 decreased cell viability, clonogenicity, and cell proliferation, resulting in increases in apoptosis and cell cycle arrest in the G2/M phase (p < 0.05). NT157 treatment inhibited IRS1/2, JAK2/STAT, and NFκB signaling, and it activated the AP-1 complex, downregulated four oncogenes (CCND1, MYB, WT1, and NFKB1), and upregulated three apoptotic-related genes (CDKN1A, FOS, and JUN) (p < 0.05). NT157 induced genotoxic stress in a JAK2/STAT-independent manner. NT157 inhibited erythropoietin-independent colony formation in cells from polycythemia vera patients (p < 0.05). These findings further elucidate the mechanism of NT157 action in a MPN context and suggest that targeting IRS1/2 proteins may represent a promising therapeutic strategy for MPN.
Collapse
Affiliation(s)
- Bruna Alves Fenerich
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-Based Therapy, Sao Paulo Research Foundation, Ribeirão Preto, São Paulo, Brazil
| | - Jaqueline Cristina Fernandes
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-Based Therapy, Sao Paulo Research Foundation, Ribeirão Preto, São Paulo, Brazil
| | - Ana Paula Nunes Rodrigues Alves
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-Based Therapy, Sao Paulo Research Foundation, Ribeirão Preto, São Paulo, Brazil
| | - Juan Luiz Coelho-Silva
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-Based Therapy, Sao Paulo Research Foundation, Ribeirão Preto, São Paulo, Brazil
| | - Renata Scopim-Ribeiro
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-Based Therapy, Sao Paulo Research Foundation, Ribeirão Preto, São Paulo, Brazil
| | - Priscila Santos Scheucher
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
| | - Christopher A Eide
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
- Howard Hughes Medical Institute, Portland, OR, USA
| | - Cristina E Tognon
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
- Howard Hughes Medical Institute, Portland, OR, USA
| | - Brian J Druker
- Knight Cancer Institute, Oregon Health & Science University, Portland, OR, USA
- Howard Hughes Medical Institute, Portland, OR, USA
| | - Eduardo Magalhães Rego
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
- Center for Cell-Based Therapy, Sao Paulo Research Foundation, Ribeirão Preto, São Paulo, Brazil
- Department of Internal Medicine, University of São Paulo Medical School, São Paulo, Brazil
| | - João Agostinho Machado-Neto
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
- Department of Pharmacology, Institute of Biomedical Sciences of the University of São Paulo, São Paulo, Brazil
| | - Fabiola Traina
- Department of Medical Images, Hematology, and Clinical Oncology, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil.
- Center for Cell-Based Therapy, Sao Paulo Research Foundation, Ribeirão Preto, São Paulo, Brazil.
| |
Collapse
|
6
|
Zhu Y, Mordaunt CE, Yasui DH, Marathe R, Coulson RL, Dunaway KW, Jianu JM, Walker CK, Ozonoff S, Hertz-Picciotto I, Schmidt RJ, LaSalle JM. Placental DNA methylation levels at CYP2E1 and IRS2 are associated with child outcome in a prospective autism study. Hum Mol Genet 2019; 28:2659-2674. [PMID: 31009952 PMCID: PMC6687952 DOI: 10.1093/hmg/ddz084] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 03/25/2019] [Accepted: 04/15/2019] [Indexed: 12/20/2022] Open
Abstract
DNA methylation acts at the interface of genetic and environmental factors relevant for autism spectrum disorder (ASD). Placenta, normally discarded at birth, is a potentially rich source of DNA methylation patterns predictive of ASD in the child. Here, we performed whole methylome analyses of placentas from a prospective study MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) of high-risk pregnancies. A total of 400 differentially methylated regions (DMRs) discriminated placentas stored from children later diagnosed with ASD compared to typically developing controls. These ASD DMRs were significantly enriched at promoters, mapped to 596 genes functionally enriched in neuronal development, and overlapped genetic ASD risk. ASD DMRs at CYP2E1 and IRS2 reached genome-wide significance, replicated by pyrosequencing and correlated with expression differences in brain. Methylation at CYP2E1 associated with both ASD diagnosis and genotype within the DMR. In contrast, methylation at IRS2 was unaffected by within DMR genotype but modified by preconceptional maternal prenatal vitamin use. This study therefore identified two potentially useful early epigenetic markers for ASD in placenta.
Collapse
Affiliation(s)
- Yihui Zhu
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| | - Charles E Mordaunt
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| | - Dag H Yasui
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| | - Ria Marathe
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| | - Rochelle L Coulson
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| | - Keith W Dunaway
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| | - Julia M Jianu
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| | - Cheryl K Walker
- Department of Obstetrics & Gynecology, School of Medicine, MIND Institute, University of California, Davis, 95616, USA
| | - Sally Ozonoff
- MIND Institute, University of California, Davis, CA, USA
- Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California, Davis, CA, USA
| | - Irva Hertz-Picciotto
- MIND Institute, University of California, Davis, CA, USA
- Department of Public Health Sciences, University of California, Davis, CA, USA
| | - Rebecca J Schmidt
- MIND Institute, University of California, Davis, CA, USA
- Department of Public Health Sciences, University of California, Davis, CA, USA
| | - Janine M LaSalle
- Department of Medical Microbiology and Immunology, University of California, Davis, CA, USA
- Genome Center, University of California, Davis, CA, USA
- MIND Institute, University of California, Davis, CA, USA
| |
Collapse
|
7
|
Baldini G, Phelan KD. The melanocortin pathway and control of appetite-progress and therapeutic implications. J Endocrinol 2019; 241:R1-R33. [PMID: 30812013 PMCID: PMC6500576 DOI: 10.1530/joe-18-0596] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 01/22/2019] [Indexed: 12/19/2022]
Abstract
The initial discovery that ob/ob mice become obese because of a recessive mutation of the leptin gene has been crucial to discover the melanocortin pathway to control appetite. In the melanocortin pathway, the fed state is signaled by abundance of circulating hormones such as leptin and insulin, which bind to receptors expressed at the surface of pro-opiomelanocortin (POMC) neurons to promote processing of POMC to the mature hormone α-melanocyte-stimulating hormone (α-MSH). The α-MSH released by POMC neurons then signals to decrease energy intake by binding to melanocortin-4 receptor (MC4R) expressed by MC4R neurons to the paraventricular nucleus (PVN). Conversely, in the 'starved state' activity of agouti-related neuropeptide (AgRP) and of neuropeptide Y (NPY)-expressing neurons is increased by decreased levels of circulating leptin and insulin and by the orexigenic hormone ghrelin to promote food intake. This initial understanding of the melanocortin pathway has recently been implemented by the description of the complex neuronal circuit that controls the activity of POMC, AgRP/NPY and MC4R neurons and downstream signaling by these neurons. This review summarizes the progress done on the melanocortin pathway and describes how obesity alters this pathway to disrupt energy homeostasis. We also describe progress on how leptin and insulin receptors signal in POMC neurons, how MC4R signals and how altered expression and traffic of MC4R change the acute signaling and desensitization properties of the receptor. We also describe how the discovery of the melanocortin pathway has led to the use of melanocortin agonists to treat obesity derived from genetic disorders.
Collapse
Affiliation(s)
- Giulia Baldini
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kevin D. Phelan
- Department of Neurobiology & Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| |
Collapse
|
8
|
Neto JGO, Bento-Bernardes T, Pazos-Moura CC, Oliveira KJ. Maternal cinnamon intake during lactation led to visceral obesity and hepatic metabolic dysfunction in the adult male offspring. Endocrine 2019; 63:520-530. [PMID: 30276593 DOI: 10.1007/s12020-018-1775-1] [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: 07/31/2018] [Accepted: 09/24/2018] [Indexed: 10/28/2022]
Abstract
PURPOSE Studies with foods, known to promote health benefits in addition to the nutritive value, show that their consumption by pregnant and/or lactating females could induce negative outcomes to the offspring. It is well characterized that cinnamon intake promotes benefits to energy homeostasis. The present study aimed to analyze the effects of the consumption of an aqueous extract of cinnamon by lactating female rats on the endocrine-metabolic outcomes in the adult offspring. METHODS Lactating dams (Wistar rats) were supplemented with cinnamon aqueous extract (400 mg/kg body weight/day) for the entire lactating period. The male adult offspring were evaluated at 180 days old (CinLac). RESULTS The offspring presented visceral obesity (P = 0.001), hyperleptinemia (P = 0.002), and hyperinsulinemia (P = 0.016). In the liver, CinLac exhibited reduced p-IRβ (P = 0.018) suggesting insulin resistance. However, phosphorylation of IRS1 (P = 0.041) and AKT (P = 0.050) were increased. JAK2 (P = 0.030) and p-STAT3 (P = 0.015) expressions were higher, suggesting that the activation of IRS1/AKT in the CinLac group could have resulted from the increased activation of leptin signaling. Although we observed no changes in the gluconeogenic pathway, the CinLac group exhibited lower hepatic glycogen content (P = 0.005) accompanied by increased p-GSK3β (P = 0.011). In addition, the CinLac group showed increased hepatic triacylglycerol content (P = 0.049) and a mild steatosis (P = 0.001), accompanied by reduced PPARα mRNA expression (P = 0.005). CONCLUSION We conclude that maternal intake of aqueous extract of cinnamon induces long-term molecular, metabolic, and hormonal changes in the adult progeny, including visceral obesity, higher lipid accumulation, and lower glycogen content in the liver.
Collapse
Affiliation(s)
| | - Thais Bento-Bernardes
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21949-900, RJ, Brazil
| | - Carmen Cabanelas Pazos-Moura
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21949-900, RJ, Brazil
| | - Karen Jesus Oliveira
- Departamento de Fisiologia e Farmacologia, Universidade Federal Fluminense, Niterói, 24210-130, RJ, Brazil.
| |
Collapse
|
9
|
Gorgisen G, Hapil FZ, Yilmaz O, Cetin Z, Pehlivanoglu S, Ozbudak IH, Erdogan A, Ozes ON. Identification of novel mutations of Insulin Receptor Substrate 1 (IRS1) in tumor samples of non-small cell lung cancer (NSCLC): Implications for aberrant insulin signaling in development of cancer. Genet Mol Biol 2019; 42:15-25. [PMID: 30807634 PMCID: PMC6428125 DOI: 10.1590/1678-4685-gmb-2017-0307] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 06/13/2018] [Indexed: 02/08/2023] Open
Abstract
Lung cancer is the leading cause of cancer-related death, and NSCLC constitutes nearly 85%-90% of all cases. The IRS proteins function as adaptors and transmit signals from multiple receptors. Upon binding of insulin to the insulin receptor (IR), IRS1 is phosphorylated at several YXXM motifs creating docking sites for the binding of PI3Kp85, which activates AKT kinase. Therefore, we thought that gain of function mutantions of IRS1 could be related to development of lung cancer. In line with this, we wanted determine whether the IRS1 gene was mutated in the coding regions surrounding YXXM motifs. We sequenced the coding regions surrounding YXXM motifs of IRS1 using tumor samples of 42 NSCLC patients and 40 matching controls and found heterozygote p.S668T mutation in nine of 42 samples and four of nine also had the p.D674H mutation. We generated IRS1 expression vectors harboring p.S668T, p.D674H and double mutants. Expression of the mutants differentially affected insulin-induced phosphorylation of IRS1, AKT, ERK, and STAT3. Also, our mutants induced proliferation, glucose uptake, inhibited the migration of 293T cells and affected the responsiveness of the cells to cisplatin and radiation. Our results suggest that these novel mutations play a role in the phenotype of lung cancer.
Collapse
Affiliation(s)
| | | | - Ozlem Yilmaz
- Faculty of Medicine, Akdeniz University, Antalya, Turkey
| | - Zafer Cetin
- Faculty of Medicine, Sanko University, Gaziantep, Turkey
| | | | | | | | | |
Collapse
|
10
|
Jiang H, Yamashita Y, Nakamura A, Croft K, Ashida H. Quercetin and its metabolite isorhamnetin promote glucose uptake through different signalling pathways in myotubes. Sci Rep 2019; 9:2690. [PMID: 30804434 PMCID: PMC6389993 DOI: 10.1038/s41598-019-38711-7] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/23/2018] [Indexed: 12/22/2022] Open
Abstract
Quercetin and its metabolite isorhamnetin elicit various beneficial effects on human health. However, their bioavailability is low. In this study, we investigated whether low concentrations in the physiological range could promote glucose uptake in L6 myotubes, as well as the underlying molecular mechanisms. We found that 0.1 nM and 1 nM quercetin or 1 nM isorhamnetin significantly increased glucose uptake via translocation of glucose transporter type 4 (GLUT4) to the plasma membrane of L6 myotubes. Quercetin principally activated the CaMKKβ/AMPK signalling pathway at these concentrations, but also activated IRS1/PI3K/Akt signalling at 10 nM. In contrast, 1 nM and 10 nM isorhamnetin principally activated the JAK/STAT pathway. Treatment with siAMPKα and siJAK2 abolished quercetin- and isorhamnetin-induced GLUT4 translocation, respectively. However, treatment with siJAK3 did not affect isorhamnetin-induced GLUT4 translocation, indicating that isorhamnetin induced GLUT4 translocation mainly through JAK2, but not JAK3, signalling. Thus, quercetin preferably activated the AMPK pathway and, accordingly, stimulated IRS1/PI3K/Akt signalling, while isorhamnetin activated the JAK2/STAT pathway. Furthermore, after oral administration of quercetin glycoside at 10 and 100 mg/kg body weight significantly induced GLUT4 translocation to the plasma membrane of skeletal muscles in mice. In the same animals, plasma concentrations of quercetin aglycone form were 4.95 and 6.80 nM, respectively. In conclusion, at low-concentration ranges, quercetin and isorhamnetin promote glucose uptake by increasing GLUT4 translocation via different signalling pathways in skeletal muscle cells; thus, these compounds may possess beneficial functions for maintaining glucose homeostasis by preventing hyperglycaemia at physiological concentrations.
Collapse
Affiliation(s)
- Hao Jiang
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Yoko Yamashita
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Asuka Nakamura
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, 657-8501, Japan
| | - Kevin Croft
- School of Biomedical Science, The University of Western Australia, Perth, WA, 6009, Australia
| | - Hitoshi Ashida
- Department of Agrobioscience, Graduate School of Agricultural Science, Kobe University, Kobe, Hyogo, 657-8501, Japan.
| |
Collapse
|
11
|
Bifari F, Manfrini R, Dei Cas M, Berra C, Siano M, Zuin M, Paroni R, Folli F. Multiple target tissue effects of GLP-1 analogues on non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). Pharmacol Res 2018; 137:219-229. [PMID: 30359962 DOI: 10.1016/j.phrs.2018.09.025] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 09/11/2018] [Accepted: 09/24/2018] [Indexed: 12/12/2022]
Abstract
Accumulating experimental and clinical evidences over the last decade indicate that GLP-1 analogues have a series of central nervous system and peripheral target tissues actions which are able to significantly influence the liver metabolism. GLP-1 analogues pleiotropic effects proved to be efficacious in T2DM subjects not only reducing liver steatosis and ameliorating NAFLD and NASH, but also in lowering plasma glucose and liver inflammation, improving cardiac function and protecting from kidney dysfunction. While the experimental and clinical data are robust, the precise mechanisms of action potentially involved in these protective multi-target effects need further investigation. Here we present a systematic review of the most recent literature data on the multi-target effects of GLP-1 analogues on the liver, on adipose and muscular tissue and on the nervous system, all capable of influencing significant aspects of the fatty liver disease physiopathology. From this analysis, we can conclude that the multi-target beneficial action of the GLP-1 analogues could explain the positive effects observed in animal and human models on progression of NAFLD to NASH.
Collapse
Affiliation(s)
- Francesco Bifari
- Laboratory of Cell Metabolism and Regenerative Medicine, Department of Medical Biotechnology and Translational Medicine, University of Milan, Milan, Italy
| | - Roberto Manfrini
- Department of Internal Medicine ASST Santi Paolo e Carlo, Milan, Italy
| | - Michele Dei Cas
- Laboratory of Clinical Biochemistry and Mass Spectrometry, Department of Health Science, University of Milan, Milan, Italy
| | - Cesare Berra
- Metabolic Disease and Diabetes, Humanitas Research Hospital, Rozzano, Milan, Italy
| | - Matteo Siano
- Department of Internal Medicine ASST Santi Paolo e Carlo, Milan, Italy
| | - Massimo Zuin
- Unit of Medicine, Gastroenterology and Hepatology, Milan, Italy
| | - Rita Paroni
- Laboratory of Clinical Biochemistry and Mass Spectrometry, Department of Health Science, University of Milan, Milan, Italy
| | - Franco Folli
- Unit of Endocrinology and Metabolism ASST Santi Paolo e Carlo, Department of Health Science, University of Milan, Milan, Italy.
| |
Collapse
|
12
|
Machado-Neto JA, Fenerich BA, Rodrigues Alves APN, Fernandes JC, Scopim-Ribeiro R, Coelho-Silva JL, Traina F. Insulin Substrate Receptor (IRS) proteins in normal and malignant hematopoiesis. Clinics (Sao Paulo) 2018; 73:e566s. [PMID: 30328953 PMCID: PMC6169455 DOI: 10.6061/clinics/2018/e566s] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Accepted: 07/30/2018] [Indexed: 12/31/2022] Open
Abstract
The insulin receptor substrate (IRS) proteins are a family of cytoplasmic proteins that integrate and coordinate the transmission of signals from the extracellular to the intracellular environment via transmembrane receptors, thus regulating cell growth, metabolism, survival and proliferation. The PI3K/AKT/mTOR and MAPK signaling pathways are the best-characterized downstream signaling pathways activated by IRS signaling (canonical pathways). However, novel signaling axes involving IRS proteins (noncanonical pathways) have recently been identified in solid tumor and hematologic neoplasm models. Insulin receptor substrate-1 (IRS1) and insulin receptor substrate-2 (IRS2) are the best-characterized IRS proteins in hematologic-related processes. IRS2 binds to important cellular receptors involved in normal hematopoiesis (EPOR, MPL and IGF1R). Moreover, the identification of IRS1/ABL1 and IRS2/JAK2V617F interactions and their functional consequences has opened a new frontier for investigating the roles of the IRS protein family in malignant hematopoiesis. Insulin receptor substrate-4 (IRS4) is absent in normal hematopoietic tissues but may be expressed under abnormal conditions. Moreover, insulin receptor substrate-5 (DOK4) and insulin receptor substrate-6 (DOK5) are linked to lymphocyte regulation. An improved understanding of the signaling pathways mediated by IRS proteins in hematopoiesis-related processes, along with the increased development of agonists and antagonists of these signaling axes, may generate new therapeutic approaches for hematological diseases. The scope of this review is to recapitulate and review the evidence for the functions of IRS proteins in normal and malignant hematopoiesis.
Collapse
Affiliation(s)
- João Agostinho Machado-Neto
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
- Departamento de Farmacologia do Instituto de Ciencias Biomedicas da Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Bruna Alves Fenerich
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Ana Paula Nunes Rodrigues Alves
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Jaqueline Cristina Fernandes
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Renata Scopim-Ribeiro
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Juan Luiz Coelho-Silva
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
| | - Fabiola Traina
- Departamento de Medicina Interna, Faculdade de Medicina de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo, SP, BR
- *Corresponding author. E-mail:
| |
Collapse
|
13
|
de Melo Campos P, Machado-Neto JA, Eide CA, Savage SL, Scopim-Ribeiro R, da Silva Souza Duarte A, Favaro P, Lorand-Metze I, Costa FF, Tognon CE, Druker BJ, Olalla Saad ST, Traina F. IRS2 silencing increases apoptosis and potentiates the effects of ruxolitinib in JAK2V617F-positive myeloproliferative neoplasms. Oncotarget 2016; 7:6948-59. [PMID: 26755644 PMCID: PMC4872760 DOI: 10.18632/oncotarget.6851] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Accepted: 01/01/2016] [Indexed: 01/07/2023] Open
Abstract
The recurrent V617F mutation in JAK2 (JAK2V617F) has emerged as the primary contributor to the pathogenesis of myeloproliferative neoplasms (MPN). However, the lack of complete response in most patients treated with the JAK1/2 inhibitor, ruxolitinib, indicates the need for identifying pathways that cooperate with JAK2. Activated JAK2 was found to be associated with the insulin receptor substrate 2 (IRS2) in non-hematological cells. We identified JAK2/IRS2 binding in JAK2V617F HEL cells, but not in the JAK2WT U937 cell line. In HEL cells, IRS2 silencing decreased STAT5 phosphorylation, reduced cell viability and increased apoptosis; these effects were enhanced when IRS2 silencing was combined with ruxolitinib. In U937 cells, IRS2 silencing neither reduced cell viability nor induced apoptosis. IRS1/2 pharmacological inhibition in primary MPN samples reduced cell viability in JAK2V617F-positive but not JAK2WT specimens; combination with ruxolitinib had additive effects. IRS2 expression was significantly higher in CD34+ cells from essential thrombocythemia patients compared to healthy donors, and in JAK2V617F MPN patients when compared to JAK2WT. Our data indicate that IRS2 is a binding partner of JAK2V617F in MPN. IRS2 contributes to increased cell viability and reduced apoptosis in JAK2-mutated cells. Combined pharmacological inhibition of IRS2 and JAK2 may have a potential clinical application in MPN.
Collapse
Affiliation(s)
- Paula de Melo Campos
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - João A Machado-Neto
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - Christopher A Eide
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA.,Howard Hughes Medical Institute, Portland, Oregon, USA
| | - Samantha L Savage
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA
| | - Renata Scopim-Ribeiro
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil.,Current address: Department of Internal Medicine, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
| | - Adriana da Silva Souza Duarte
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - Patricia Favaro
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil.,Current address: Department of Biological Sciences, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Irene Lorand-Metze
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - Fernando F Costa
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - Cristina E Tognon
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA.,Howard Hughes Medical Institute, Portland, Oregon, USA
| | - Brian J Druker
- Knight Cancer Institute, Oregon Health & Science University, Portland, Oregon, USA.,Howard Hughes Medical Institute, Portland, Oregon, USA
| | - Sara T Olalla Saad
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil
| | - Fabiola Traina
- Hematology and Hemotherapy Center - University of Campinas/Hemocentro - Unicamp, Instituto Nacional de Ciência e Tecnologia do Sangue, Campinas, São Paulo, Brazil.,Current address: Department of Internal Medicine, University of São Paulo at Ribeirão Preto Medical School, Ribeirão Preto, São Paulo, Brazil
| |
Collapse
|
14
|
Leptin-Induced JAK/STAT Signaling and Cancer Growth. Vaccines (Basel) 2016; 4:vaccines4030026. [PMID: 27472371 PMCID: PMC5041020 DOI: 10.3390/vaccines4030026] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 07/11/2016] [Accepted: 07/12/2016] [Indexed: 02/08/2023] Open
Abstract
Growth factor and cytokine signaling can influence the development of several cancer types. One of the key players in the development of cancer is the Janus kinas (JAK) signal transducer of activators of transcription (STAT) signaling pathway. The majority of growth factors and cytokine interactions with their membrane-bound receptors trigger JAK-STAT activation. The influential relationship between obesity and cancer is a fact. However, there is a complex sequence of events contributing to the regulation of this mechanism to promote tumor growth, yet to be fully elucidated. The JAK-STAT pathway is influenced by obesity-associated changes that have been shown to impact cancer growth and progression. This intricate process is highly regulated by a vast array of adipokines and cytokines that exert their pleiotropic effects on cancer cells to enhance metastasis to distant target sites. Leptin is a cytokine, or more precise, an adipokine secreted mainly by adipose tissue that requires JAK-STAT activation to exert its biological functions. Leptin is the central regulator of energy balance and appetite. Leptin binding to its receptor OB-R in turn activates JAK-STAT, which induces proliferation, angiogenesis, and anti-apoptotic events in normal cells and malignant cells expressing the receptor. Leptin also induces crosstalk with Notch and IL-1 (NILCO), which involves other angiogenic factors promoting tumor growth. Therefore, the existence of multiple novel classes of therapeutics that target the JAK/STAT pathway has significant clinical implications. Then, the identification of the signaling networks and factors that regulate the obesity-cancer link to which potential pharmacologic interventions can be implemented to inhibit tumor growth and metastasis. In this review, we will discuss the specific relationship between leptin-JAK-STAT signaling and cancer.
Collapse
|
15
|
Chemical and Hormonal Effects on STAT5b-Dependent Sexual Dimorphism of the Liver Transcriptome. PLoS One 2016; 11:e0150284. [PMID: 26959237 PMCID: PMC4784907 DOI: 10.1371/journal.pone.0150284] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 02/11/2016] [Indexed: 12/21/2022] Open
Abstract
The growth hormone (GH)-activated transcription factor signal transducer and activator of transcription 5b (STAT5b) is a key regulator of sexually dimorphic gene expression in the liver. Suppression of hepatic STAT5b signaling is associated with lipid metabolic dysfunction leading to steatosis and liver cancer. In the companion publication, a STAT5b biomarker gene set was identified and used in a rank-based test to predict both increases and decreases in liver STAT5b activation status/function with high (≥ 97%) accuracy. Here, this computational approach was used to identify chemicals and hormones that activate (masculinize) or suppress (feminize) STAT5b function in a large, annotated mouse liver and primary hepatocyte gene expression compendium. Exposure to dihydrotestosterone and thyroid hormone caused liver masculinization, whereas glucocorticoids, fibroblast growth factor 15, and angiotensin II caused liver feminization. In mouse models of diabetes and obesity, liver feminization was consistently observed and was at least partially reversed by leptin or resveratrol exposure. Chemical-induced feminization of male mouse liver gene expression profiles was a relatively frequent phenomenon: of 156 gene expression biosets from chemically-treated male mice, 29% showed feminization of liver STAT5b function, while <1% showed masculinization. Most (93%) of the biosets that exhibited feminization of male liver were also associated with activation of one or more xenobiotic-responsive receptors, most commonly constitutive activated receptor (CAR) or peroxisome proliferator-activated receptor alpha (PPARα). Feminization was consistently associated with increased expression of peroxisome proliferator-activated receptor gamma (Pparg) but not other lipogenic transcription factors linked to steatosis. GH-activated STAT5b signaling in mouse liver is thus commonly altered by diverse chemicals, and provides a linkage between chemical exposure and dysregulated gene expression associated with adverse effects on the liver.
Collapse
|
16
|
Xin XM, Zhong MX, Yang GL, Peng Y, Zhang YL, Zhu W. GW4064, a farnesoid X receptor agonist, upregulates adipokine expression in preadipocytes and HepG2 cells. World J Gastroenterol 2014; 20:15727-15735. [PMID: 25400456 PMCID: PMC4229537 DOI: 10.3748/wjg.v20.i42.15727] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/13/2014] [Accepted: 07/11/2014] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of GW4064 on the expression of adipokines and their receptors during differentiation of 3T3-L1 preadipocytes and in HepG2 cells.
METHODS: The mRNA expression of farnesoid X receptor (FXR), peroxisome proliferator-activated receptor-gamma 2 (PPAR-γ2), adiponectin, leptin, resistin, adiponectin receptor 1 (AdipoR1), adiponectin receptor 2 (AdipoR2), and the long isoform of leptin receptor (OB-Rb) and protein levels of adiponectin, leptin, and resistin were determined using fluorescent real-time PCR and enzyme linked immunosorbent assay, respectively, on days 0, 2, 4, 6, and 8 during the differentiation of 3T3-L1 preadipocytes exposed to GW4064. Moreover, mRNA expression of AdipoR2 and OB-Rb was also examined using fluorescent real-time PCR at 0, 12, 24, and 48 h in HepG2 cells treated with GW4064.
RESULTS: The mRNA expression of FXR, PPAR-γ2, adiponectin, leptin, resistin, AdipoR1, AdipoR2, and OB-Rb and protein levels of adiponectin, leptin, and resistin increased along with differentiation of 3T3-L1 preadipocytes (P < 0.05 for all). The mRNA expression of FXR, PPAR-γ2, adiponectin, leptin, and AdipoR2 in 3T3-L1 preadipocytes, and AdipoR2 and OB-Rb in HepG2 cells was significantly increased after treatment with GW4064, when compared with the control group (P < 0.05 for all). A similar trend was observed for protein levels of adipokines (including adiponectin, leptin and resistin). However, the expression of resistin, AdipoR1, and OB-Rb in 3T3-L1 cells did not change after treatment with GW4064.
CONCLUSION: The FXR agonist through regulating, at least partially, the expression of adipokines and their receptors could offer an innovative way for counteracting the progress of metabolic diseases such as nonalcoholic fatty liver disease.
Collapse
MESH Headings
- 3T3-L1 Cells
- Adipocytes/drug effects
- Adipocytes/metabolism
- Adipokines/genetics
- Adipokines/metabolism
- Animals
- Hep G2 Cells
- Hepatocytes/drug effects
- Hepatocytes/metabolism
- Humans
- Isoxazoles/pharmacology
- Mice
- PPAR gamma/drug effects
- PPAR gamma/genetics
- PPAR gamma/metabolism
- RNA, Messenger/metabolism
- Receptors, Adiponectin/drug effects
- Receptors, Adiponectin/genetics
- Receptors, Adiponectin/metabolism
- Receptors, Cytoplasmic and Nuclear/agonists
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Leptin/drug effects
- Receptors, Leptin/genetics
- Receptors, Leptin/metabolism
- Signal Transduction/drug effects
- Time Factors
- Up-Regulation
Collapse
|
17
|
Abstract
Osteopenia and osteoporosis are common manifestations in inflammatory bowel diseases (IBD) but the pathogenetic mechanism of bone loss in IBD is only partially understood. There is evidence that fat mass is an important determinant of the bone mineral density and adipose-derived factors seem to play an important role for the association between fat mass and bone mass. The association between adiposity and low bone density is rather poorly studied in IBD, but emerging data on adipokines in IBD in relation to osteoporosis provide a novel pathophysiological concept that may shed light on the etiology of bone loss in IBD. It could be suggested that adipokines interfere in bone metabolism by altering the sensitive balance between osteoblasts and osteoclasts although further studies in this setting are needed.
Collapse
|
18
|
Suppressor of cytokine signalling (SOCS) proteins as guardians of inflammatory responses critical for regulating insulin sensitivity. Biochem J 2014; 461:177-88. [PMID: 24966052 DOI: 10.1042/bj20140143] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Overactivation of immune pathways in obesity is an important cause of insulin resistance and thus new approaches aimed to limit inflammation or its consequences may be effective for treating Type 2 diabetes. The SOCS (suppressors of cytokine signalling) are a family of proteins that play an essential role in mediating inflammatory responses in both immune cells and metabolic organs such as the liver, adipose tissue and skeletal muscle. In the present review we discuss the role of SOCS1 and SOCS3 in controlling immune cells such as macrophages and T-cells and the impact this can have on systemic inflammation and insulin resistance. We also dissect the mechanisms by which SOCS (1-7) regulate insulin signalling in different tissues including their impact on the insulin receptor and insulin receptor substrates. Lastly, we discuss the important findings from SOCS whole-body and tissue-specific null mice, which implicate an important role for these proteins in controlling insulin action and glucose homoeostasis in obesity.
Collapse
|
19
|
Nazarians-Armavil A, Menchella JA, Belsham DD. Cellular insulin resistance disrupts leptin-mediated control of neuronal signaling and transcription. Mol Endocrinol 2013; 27:990-1003. [PMID: 23579487 DOI: 10.1210/me.2012-1338] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Central resistance to the actions of insulin and leptin is associated with the onset of obesity and type 2 diabetes mellitus, whereas leptin and insulin signaling is essential for both glucose and energy homeostasis. Although it is known that leptin resistance can lead to attenuated insulin signaling, whether insulin resistance can lead to or exacerbate leptin resistance is unknown. To investigate the molecular events underlying crosstalk between these signaling pathways, immortalized hypothalamic neuronal models, rHypoE-19 and mHypoA-2/10, were used. Prolonged insulin exposure was used to induce cellular insulin resistance, and thereafter leptin-mediated regulation of signal transduction and gene expression was assessed. Leptin directly repressed agouti-related peptide mRNA levels but induced urocortin-2, insulin receptor substrate (IRS)-1, IRS2, and IR transcription, through leptin-mediated phosphatidylinositol 3-kinase/Akt activation. Neuronal insulin resistance, as assessed by attenuated Akt phosphorylation, blocked leptin-mediated signal transduction and agouti-related peptide, urocortin-2, IRS1, IRS2, and insulin receptor synthesis. Insulin resistance caused a substantial decrease in insulin receptor protein levels, forkhead box protein 1 phosphorylation, and an increase in suppressor of cytokine signaling 3 protein levels. Cellular insulin resistance may cause or exacerbate neuronal leptin resistance and, by extension, obesity. It is essential to unravel the effects of neuronal insulin resistance given that both peripheral, as well as the less widely studied central insulin resistance, may contribute to the development of metabolic, reproductive, and cardiovascular disorders. This study provides improved understanding of the complex cellular crosstalk between insulin-leptin signal transduction that is disrupted during neuronal insulin resistance.
Collapse
Affiliation(s)
- Anaies Nazarians-Armavil
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 Kings College Circle, Toronto, Ontario, Canada M5S 1A8
| | | | | |
Collapse
|
20
|
Lack of kinin B1 receptor potentiates leptin action in the liver. J Mol Med (Berl) 2013; 91:851-60. [DOI: 10.1007/s00109-013-1004-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 01/08/2013] [Accepted: 01/21/2013] [Indexed: 12/18/2022]
|
21
|
Leptin attenuates lipopolysaccharide-induced apoptosis of thymocytes partially via down-regulation of cPLA2 and p38 MAPK activation. Int Immunopharmacol 2013; 15:620-7. [PMID: 23376443 DOI: 10.1016/j.intimp.2013.01.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Revised: 01/14/2013] [Accepted: 01/17/2013] [Indexed: 01/11/2023]
Abstract
Leptin, a 16-kDa protein that is mainly secreted by adipocytes, plays a protective role in many cell types. It has been shown that leptin acts in the central and peripheral immune system to protect thymocytes. Cytosolic phospholipase A(2) (cPLA(2)) is an enzyme that can specifically initiate the release of arachidonic acid (AA) to produce eicosanoids, which regulate inflammation and immune responses. Our previous work has shown that leptin is important to prevent apoptosis of thymocytes. However, the role of cPLA(2) is still unclear, and the precise mechanism also remains to be elucidated. In this work, we demonstrated that leptin inhibited the LPS-induced toxicity and apoptosis of thymocytes. Western blot and RT-PCR showed that leptin led to a reduction of cPLA(2) activity and mRNA level, as well as caspase-3 cleavage. Moreover, we found that leptin could decrease the activation of p38 MAPK. Accordingly, we pre-treated apoptotic thymocytes with the p38 MAPK inhibitor, SB203580 and observed an effect similar to the leptin alone treated group. SB203580 also suppressed expression of cPLA(2) and cleavage of caspase-3. Based on these results, we suggest that leptin could attenuate LPS-induced apoptotic injury in mouse thymocyte cells, mainly through the p38/cPLA(2) signalling pathway. The study of the regulatory role of leptin in LPS-induced thymocyte apoptosis can help to explain the role of leptin in the immune system and may provide a novel treatment option in cases of severe trauma, infection, shock, organ failure and autoimmune disease caused by thymic atrophy.
Collapse
|
22
|
Pimentel GD, Dornellas APS, Rosa JC, Lira FS, Cunha CA, Boldarine VT, de Souza GIH, Hirata AE, Nascimento CMO, Oyama LM, Watanabe RLH, Ribeiro EB. High-fat diets rich in soy or fish oil distinctly alter hypothalamic insulin signaling in rats. J Nutr Biochem 2012; 23:822-8. [PMID: 21852082 DOI: 10.1016/j.jnutbio.2011.04.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Revised: 02/24/2011] [Accepted: 04/08/2011] [Indexed: 11/30/2022]
Abstract
Hypothalamic insulin inhibits food intake, preventing obesity. High-fat feeding with polyunsaturated fats may be obesogenic, but their effect on insulin action has not been elucidated. The present study evaluated insulin hypophagia and hypothalamic signaling after central injection in rats fed either control diet (15% energy from fat) or high-fat diets (50% energy from fat) enriched with either soy or fish oil. Soy rats had increased fat pad weight and serum leptin with normal body weight, serum lipid profile and peripheral insulin sensitivity. Fish rats had decreased body and fat pad weight, low leptin and corticosterone levels, and improved serum lipid profile. A 20-mU dose of intracerebroventricular (ICV) insulin inhibited food intake in control and fish groups, but failed to do so in the soy group. Hypothalamic protein levels of IR, IRS-1, IRS-2, Akt, mTOR, p70S6K and AMPK were similar among groups. ICV insulin stimulated IR tyrosine phosphorylation in control (68%), soy (36%) and fish (34%) groups. Tyrosine phosphorylation of the pp185 band was significantly stimulated in control (78%) and soy (53%) rats, but not in fish rats. IRS-1 phosphorylation was stimulated only in control rats (94%). Akt serine phosphorylation was significantly stimulated only in control (90%) and fish (78%) rats. The results showed that, rather than the energy density, the fat type was a relevant aspect of high-fat feeding, since blockade of hypothalamic insulin signal transmission and insulin hypophagia was promoted only by the high-fat soy diet, while they were preserved in the rats fed with the high-fat fish diet.
Collapse
Affiliation(s)
- Gustavo D Pimentel
- Disciplina de Fisiologia da Nutrição, Departamento de Fisiologia, Universidade Federal de São Paulo-UNIFESP, CEP 04023-062 São Paulo/SP, Brazil
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Siddle K. Molecular basis of signaling specificity of insulin and IGF receptors: neglected corners and recent advances. Front Endocrinol (Lausanne) 2012; 3:34. [PMID: 22649417 PMCID: PMC3355962 DOI: 10.3389/fendo.2012.00034] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 02/13/2012] [Indexed: 12/15/2022] Open
Abstract
Insulin and insulin-like growth factor (IGF) receptors utilize common phosphoinositide 3-kinase/Akt and Ras/extracellular signal-regulated kinase signaling pathways to mediate a broad spectrum of "metabolic" and "mitogenic" responses. Specificity of insulin and IGF action in vivo must in part reflect expression of receptors and responsive pathways in different tissues but it is widely assumed that it is also determined by the ligand binding and signaling mechanisms of the receptors. This review focuses on receptor-proximal events in insulin/IGF signaling and examines their contribution to specificity of downstream responses. Insulin and IGF receptors may differ subtly in the efficiency with which they recruit their major substrates (IRS-1 and IRS-2 and Shc) and this could influence effectiveness of signaling to "metabolic" and "mitogenic" responses. Other substrates (Grb2-associated binder, downstream of kinases, SH2Bs, Crk), scaffolds (RACK1, β-arrestins, cytohesins), and pathways (non-receptor tyrosine kinases, phosphoinositide kinases, reactive oxygen species) have been less widely studied. Some of these components appear to be specifically involved in "metabolic" or "mitogenic" signaling but it has not been shown that this reflects receptor-preferential interaction. Very few receptor-specific interactions have been characterized, and their roles in signaling are unclear. Signaling specificity might also be imparted by differences in intracellular trafficking or feedback regulation of receptors, but few studies have directly addressed this possibility. Although published data are not wholly conclusive, no evidence has yet emerged for signaling mechanisms that are specifically engaged by insulin receptors but not IGF receptors or vice versa, and there is only limited evidence for differential activation of signaling mechanisms that are common to both receptors. Cellular context, rather than intrinsic receptor activity, therefore appears to be the major determinant of whether responses to insulin and IGFs are perceived as "metabolic" or "mitogenic."
Collapse
Affiliation(s)
- Kenneth Siddle
- University of Cambridge Metabolic Research Laboratories and Department of Clinical Biochemistry, Institute of Metabolic Science, Addenbrooke's Hospital Cambridge, UK.
| |
Collapse
|
24
|
Penas-Steinhardt A, Tellechea¹ ML, Gomez-Rosso L, Brites F, Frechtel GD, Poskus E. Association of common variants in JAK2 gene with reduced risk of metabolic syndrome and related disorders. BMC MEDICAL GENETICS 2011; 12:166. [PMID: 22185674 PMCID: PMC3259043 DOI: 10.1186/1471-2350-12-166] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Accepted: 12/20/2011] [Indexed: 12/13/2022]
Abstract
BACKGROUND Disturbances in leptin and insulin signaling pathways are related to obesity and metabolic syndrome (MS) with increased risk of diabetes and cardiovascular disease. Janus kinase 2 (JAK2) is a tyrosine kinase involved in the activation of mechanisms that mediate leptin and insulin actions. We conducted a population cross-sectional study to explore the association between two common variants in JAK2 gene and MS related traits in 724 Argentinean healthy male subjects. METHODS A total of 724 unrelated men aged 37.11 ± 10.91 yr were included in a cross-sectional study. Physical examination, anthropometric measurements and biochemical analysis were determined by a standardized protocol. rs7849191 and rs3780378 were genotyped. Analyses were done separately for each SNP and followed up by haplotype analysis. RESULTS rs7849191 and rs3780378 were both associated with reduced risk of MS [p = 0.005; OR (95%CI) = 0.52 (0.33-0.80) and p = 0.006; OR (95% CI) = 0.59 (0.40-0.86) respectively, assuming a dominant model]. rs3780378 T allele was associated with triglyceridemia values under 150 mg/dl [p = 0.007; OR (95%CI) = 0.610 (0.429-0.868)] and TT carriers showed lower triglycerides (p = 0.017), triglycerides/HDL-C ratio (p = 0.022) and lipid accumulation product (p = 0.007) compared to allele C carriers. The two-SNPs-haplotype analysis was consistent with single locus analysis. CONCLUSIONS It was found for the first time, significant associations of JAK2 common variants and related haplotypes with reduced risk of MS. These findings could be explained by the role of JAK2 in insulin and/or leptin signaling.
Collapse
Affiliation(s)
- Alberto Penas-Steinhardt
- Humoral Immunity Institute "Prof. Ricardo A. Margni" (IDEHU), National Research Council (CONICET) & Chair of Immunology, School of Pharmacy and Biochemistry, University of Buenos Aires (UBA) - Argentina
| | - Mariana L Tellechea¹
- Humoral Immunity Institute "Prof. Ricardo A. Margni" (IDEHU), National Research Council (CONICET) & Chair of Immunology, School of Pharmacy and Biochemistry, University of Buenos Aires (UBA) - Argentina
- Chair of Genetic, Department of Microbiology, Inmunology and Biotecnology, School of Pharmacy and Biochemistry, University of Buenos Aires (UBA) - Argentina
| | - Leonardo Gomez-Rosso
- Laboratory of Lipids and lipoproteins, Department of Clinical Biochemistry, School of Pharmacy and Biochemistry. National Research Council (CONICET) & University of Buenos Aires (UBA) - Argentina
| | - Fernando Brites
- Laboratory of Lipids and lipoproteins, Department of Clinical Biochemistry, School of Pharmacy and Biochemistry. National Research Council (CONICET) & University of Buenos Aires (UBA) - Argentina
| | - Gustavo D Frechtel
- Chair of Genetic, Department of Microbiology, Inmunology and Biotecnology, School of Pharmacy and Biochemistry, University of Buenos Aires (UBA) - Argentina
- Genetics Division, Clinical Hospital "José de San Martín", University of Buenos Aires (UBA) - Argentina
| | - Edgardo Poskus
- Chair of Genetic, Department of Microbiology, Inmunology and Biotecnology, School of Pharmacy and Biochemistry, University of Buenos Aires (UBA) - Argentina
| |
Collapse
|
25
|
Marwarha G, Prasanthi JR, Schommer J, Dasari B, Ghribi O. Molecular interplay between leptin, insulin-like growth factor-1, and β-amyloid in organotypic slices from rabbit hippocampus. Mol Neurodegener 2011; 6:41. [PMID: 21651786 PMCID: PMC3121598 DOI: 10.1186/1750-1326-6-41] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 06/08/2011] [Indexed: 01/22/2023] Open
Abstract
Background Evidence shows that the insulin-like growth factor-1 (IGF-1) and leptin reduce β-amyloid (Aβ) production and tau phosphorylation, two major hallmarks of Alzheimer's disease (AD). IGF-1 expression involves the JAK/STAT pathway and the expression of leptin is regulated by the mammalian target of rapamycin complex 1 (mTORC1). We have previously shown that Aβ reduces leptin by inhibiting the mTORC1 pathway and Aβ was also suggested to inhibit the JAK/STAT pathway, potentially attenuating IGF-1 expression. As IGF-1 can activate mTORC1 and leptin can modulate JAK/STAT pathway, we determined the extent to which IGF-1 and leptin can upregulate the expression of one another and protect against Aβ-induced downregulation. Results We demonstrate that incubation of organotypic slices from adult rabbit hippocampus with Aβ42 downregulates IGF-1 expression by inhibiting JAK2/STAT5 pathway. Leptin treatment reverses these Aβ42 effects on IGF-1 and treatment with the STAT5 inhibitor completely abrogated the leptin-induced increase in IGF-1. Furthermore, EMSA and ChIP analyses revealed that leptin increases the STAT5 binding to the IGF-1 promoter. We also show that IGF-1 increases the expression of leptin and reverses the Aβ42-induced attenuation in leptin expression via the activation of mTORC1 signaling as the mTORC1 inhibitor rapamycin completely precluded the IGF-1-induced increase in leptin expression. Conclusion Our results demonstrate for the first time that Aβ42 downregulates IGF-1 expression and that leptin and IGF-1 rescue one another from downregulation by Aβ42. Our study provides a valuable insight into the leptin/IGF-1/Aβ interplay that may be relevant to the pathophysiology of AD.
Collapse
Affiliation(s)
- Gurdeep Marwarha
- Department of Pharmacology, Physiology and Therapeutics, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, 58202, USA.
| | | | | | | | | |
Collapse
|
26
|
Berthou F, Rouch C, Gertler A, Gerozissis K, Taouis M. Chronic central leptin infusion differently modulates brain and liver insulin signaling. Mol Cell Endocrinol 2011; 337:89-95. [PMID: 21320568 DOI: 10.1016/j.mce.2011.02.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 02/04/2011] [Accepted: 02/04/2011] [Indexed: 01/08/2023]
Abstract
Recent studies reported the impact of leptin on peripheral insulin sensitivity and glucose utilization. However, little is known concerning the effect of central leptin on hypothalamic and hepatic insulin efficiency. This study aimed to determine the consequence of chronic intra-cerebroventricular (ICV) leptin or murine leptin antagonist (MLA) infusion on hypothalamic and hepatic insulin signaling pathways, in rats. A 2-week central leptin infusion enhanced insulin-dependent Akt phosphorylation in the liver without changing PTP-1B protein expression, associated to insulin receptor (IR) upregulation and reduced IRS-1 phosphorylation on Ser302 residue. In the hypothalamus, a chronic ICV leptin infusion induced PTP-1B associated with a specific decrease in insulin-dependent Akt phosphorylation. In contrast, a chronic MLA infusion did not alter IR and PTP-1B expressions in hypothalamus and liver. Our results underline a brain leptin-dependent increase in hepatic insulin efficiency as mirrored by IR up-regulation, increased insulin-dependent Akt phosphorylation and reduced IRS-1 phosphorylation on Ser302 residue.
Collapse
Affiliation(s)
- Flavien Berthou
- Neuroendocrinologie Moléculaire de la Prise Alimentaire, University of Paris-Sud, France
| | | | | | | | | |
Collapse
|
27
|
Endocrine factors in the hypothalamic regulation of food intake in females: a review of the physiological roles and interactions of ghrelin, leptin, thyroid hormones, oestrogen and insulin. Nutr Res Rev 2011; 24:132-54. [DOI: 10.1017/s0954422411000035] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Controlling energy homeostasis involves modulating the desire to eat and regulating energy expenditure. The controlling machinery includes a complex interplay of hormones secreted at various peripheral endocrine endpoints, such as the gastrointestinal tract, the adipose tissue, thyroid gland and thyroid hormone-exporting organs, the ovary and the pancreas, and, last but not least, the brain itself. The peripheral hormones that are the focus of the present review (ghrelin, leptin, thyroid hormones, oestrogen and insulin) play integrated regulatory roles in and provide feedback information on the nutritional and energetic status of the body. As peripheral signals, these hormones modulate central pathways in the brain, including the hypothalamus, to influence food intake, energy expenditure and to maintain energy homeostasis. Since the growth of the literature on the role of various hormones in the regulation of energy homeostasis shows a remarkable and dynamic expansion, it is now becoming increasingly difficult to understand the individual and interactive roles of hormonal mechanisms in their true complexity. Therefore, our goal is to review, in the context of general physiology, the roles of the five best-known peripheral trophic hormones (ghrelin, leptin, thyroid hormones, oestrogen and insulin, respectively) and discuss their interactions in the hypothalamic regulation of food intake.
Collapse
|
28
|
Huynh FK, Levi J, Denroche HC, Gray SL, Voshol PJ, Neumann UH, Speck M, Chua SC, Covey SD, Kieffer TJ. Disruption of hepatic leptin signaling protects mice from age- and diet-related glucose intolerance. Diabetes 2010; 59:3032-40. [PMID: 20876720 PMCID: PMC2992763 DOI: 10.2337/db10-0074] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE The liver plays a critical role in integrating and controlling glucose metabolism. Thus, it is important that the liver receive and react to signals from other tissues regarding the nutrient status of the body. Leptin, which is produced and secreted from adipose tissue, is a hormone that relays information regarding the status of adipose depots to other parts of the body. Leptin has a profound influence on glucose metabolism, so we sought to determine if leptin may exert this effect in part through the liver. RESEARCH DESIGN AND METHODS To explore this possibility, we created mice that have disrupted hepatic leptin signaling using a Cre-lox approach and then investigated aspects of glucose metabolism in these animals. RESULTS The loss of hepatic leptin signaling did not alter body weight, body composition, or blood glucose levels in the mild fasting or random-fed state. However, mice with ablated hepatic leptin signaling had increased lipid accumulation in the liver. Further, as male mice aged or were fed a high-fat diet, the loss of hepatic leptin signaling protected the mice from glucose intolerance. Moreover, the mice displayed increased liver insulin sensitivity and a trend toward enhanced glucose-stimulated plasma insulin levels. Consistent with increased insulin sensitivity, mice with ablated hepatic leptin signaling had increased insulin-stimulated phosphorylation of Akt in the liver. CONCLUSIONS These data reveal that unlike a complete deficiency of leptin action, which results in impaired glucose homeostasis, disruption of leptin action in the liver alone increases hepatic insulin sensitivity and protects against age- and diet-related glucose intolerance. Thus, leptin appears to act as a negative regulator of insulin action in the liver.
Collapse
Affiliation(s)
- Frank K. Huynh
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jasna Levi
- 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
| | - Sarah L. Gray
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Peter J. Voshol
- Metabolic Research Laboratories, Institute of Metabolic Science, University of Cambridge, Cambridge, U.K
| | - Ursula H. Neumann
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Madeleine Speck
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Streamson C. Chua
- Departments of Medicine and Neuroscience, Albert Einstein College of Medicine, New York, New York
| | - Scott D. Covey
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Corresponding authors: Scott D. Covey, , and Timothy J. Kieffer,
| | - 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
- Corresponding authors: Scott D. Covey, , and Timothy J. Kieffer,
| |
Collapse
|
29
|
Pimentel GD, Zemdegs JCS, Theodoro JA, Mota JF. Does long-term coffee intake reduce type 2 diabetes mellitus risk? Diabetol Metab Syndr 2009; 1:6. [PMID: 19825198 PMCID: PMC2761298 DOI: 10.1186/1758-5996-1-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 09/16/2009] [Indexed: 01/28/2023] Open
Abstract
This review reports the evidence for a relation between long-term coffee intake and risk of type 2 diabetes mellitus. Numerous epidemiological studies have evaluated this association and, at this moment, at least fourteen out of eighteen cohort studies revealed a substantially lower risk of type 2 diabetes mellitus with frequent coffee intake. Moderate coffee intake (>/=4 cups of coffee/d of 150 mL or >/=400 mg of caffeine/d) has generally been associated with a decrease in the risk of type 2 diabetes mellitus. Besides, results of most studies suggest a dose-response relation, with greater reductions in type 2 diabetes mellitus risk with higher levels of coffee consumption. Several mechanisms underlying this protective effect, as well as the coffee components responsible for this association are suggested. Despite positive findings, it is still premature to recommend an increase in coffee consumption as a public health strategy to prevent type 2 diabetes mellitus. More population-based surveys are necessary to clarify the long-term effects of decaffeinated and caffeinated coffee intake on the risk of type 2 diabetes mellitus.
Collapse
Affiliation(s)
- Gustavo D Pimentel
- Department of Physiology, Division of Nutrition Physiology, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Juliane CS Zemdegs
- Department of Physiology, Division of Nutrition Physiology, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - Joyce A Theodoro
- Department of Nutrition, Nutrition and Health Sciences Institute, Campinas, Brazil
| | - João F Mota
- Department of Physiology, Division of Nutrition Physiology, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| |
Collapse
|
30
|
Investigation of the acute effect of leptin on the inhibition of glycogen catabolism by insulin in rat liver perfused in situ. Pharmacol Rep 2009; 61:319-24. [PMID: 19443945 DOI: 10.1016/s1734-1140(09)70038-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 02/23/2009] [Indexed: 11/22/2022]
Abstract
Leptin, a cytokine secreted by adipose tissue, has been implicated in the insulin resistance associated with obesity. Here we examined the acute influence of leptin at physiological (10 ng/ml) and supraphysiological (50 ng/ml and 100 ng/ml) concentrations on the inhibition of glycogen catabolism promoted by insulin in rat liver perfusion experiments. Perfusion of the liver with insulin (20 microU/ml) decreased the activation of glucose production (p < 0.05) and glycogenolysis by cAMP (3 microM). However, the infusion of leptin, at concentrations similar to those found in non-obese (10 ng/ml), obese (50 ng/ml), and morbidly obese (100 ng/ml) individuals did not influence the acute inhibitory effect of insulin (20 microU/ml) on glucose production and glycogenolysis stimulated by cAMP (p > 0.05).We conclude that neither physiological nor supraphysiological concentrations of leptin directly influence the inhibition of glycogen catabolism promoted by insulin in rat liver perfused in situ.
Collapse
|
31
|
Leptin inhibits glycogen catabolism but does not modify acutely the suppressive effect of insulin on glucose production and glycogenolysis stimulated by 8-Br-cAMP in rat liver perfused in situ. Pharmacol Res 2008; 59:176-82. [PMID: 19121393 DOI: 10.1016/j.phrs.2008.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 12/05/2008] [Accepted: 12/07/2008] [Indexed: 11/23/2022]
Abstract
Leptin, a hormone secreted by the adipocytes, plays a central role in glucose metabolism and the action of insulin. Here we assessed, by means of rat-liver perfusion, the direct influence of physiological (10 ng/ml) and supraphysiological (50 or 100 ng/ml) concentrations of leptin on the suppressive effect of insulin on the glucose production and glycogenolysis stimulated by 8-bromoadenosine-3':5'-monophosphate (8-Br-cAMP). Portal infusion of insulin (20 microU/ml) or leptin (10 ng/ml) reduced (p<0.05) the glucose production and glycogenolysis induced by 8-Br-cAMP (0.3 microM). However, portal infusion of physiological (10 ng/ml) and supraphysiological (50 or 100 ng/ml) concentrations of leptin together with the insulin did not modify the suppressive effect of the latter on the glucose production and glycogenolysis stimulated by 8-Br-cAMP. Moreover, prolonging the period of leptin infusion from 20 to 40 min also failed to influence the liver response to insulin. Thus, we conclude that: (a) leptin, at physiological levels, has a direct and acute effect, inhibiting the glucose production and glycogenolysis stimulated by 8-Br-cAMP; (b) leptin, at either physiological or supraphysiological concentrations, has no short-term influence on the suppressive effect of insulin on glycogen catabolism stimulated by 8-Br-cAMP.
Collapse
|
32
|
Hindmarch C, Fry M, Yao ST, Smith PM, Murphy D, Ferguson AV. Microarray analysis of the transcriptome of the subfornical organ in the rat: regulation by fluid and food deprivation. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1914-20. [DOI: 10.1152/ajpregu.90560.2008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have employed microarray technology using Affymetrix 230 2.0 genome chips to initially catalog the transcriptome of the subfornical organ (SFO) under control conditions and to also evaluate the changes (common and differential) in gene expression induced by the challenges of fluid and food deprivation. We have identified a total of 17,293 genes tagged as present in one of our three experimental conditions, transcripts, which were then used as the basis for further filtering and statistical analysis. In total, the expression of 46 genes was changed in the SFO following dehydration compared with control animals (22 upregulated and 24 downregulated), with the largest change being the greater than fivefold increase in brain-derived neurotrophic factor (BDNF) expression, while significant changes in the expression of the calcium-sensing (upregulated) and apelin (downregulated) receptors were also reported. In contrast, food deprivation caused greater than twofold changes in a total of 687 transcripts (222 upregulated and 465 downregulated), including significant reductions in vasopressin, oxytocin, promelanin concentrating hormone, cocaine amphetamine-related transcript (CART), and the endothelin type B receptor, as well as increases in the expression of the GABAB receptor. Of these regulated transcripts, we identified 37 that are commonly regulated by fasting and dehydration, nine that were uniquely regulated by dehydration, and 650 that are uniquely regulated by fasting. We also found five transcripts that were differentially regulated by fasting and dehydration including BDNF and CART. In these studies we have for the first time described the transcriptome of the rat SFO and have in addition identified genes, the expression of which is significantly modified by either water or food deprivation.
Collapse
|
33
|
Fernández-Riejos P, Goberna R, Sánchez-Margalet V. Leptin promotes cell survival and activates Jurkat T lymphocytes by stimulation of mitogen-activated protein kinase. Clin Exp Immunol 2008; 151:505-18. [PMID: 18234059 DOI: 10.1111/j.1365-2249.2007.03563.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Leptin (Ob) is a non-glycosylated peptide hormone that regulates energy homeostasis centrally, but also has systemic effects including the regulation of the immune function. We have reported previously that leptin activates human peripheral blood lymphocytes co-stimulated with phytohaemagglutinin (PHA) (4 microg/ml), which prevented the employment of pharmacological inhibitors of signalling pathways. In the present study, we used Jurkat T cells that responded to leptin with minimal PHA co-stimulation (0.25 microg/ml). The long isoform of leptin receptor is expressed on Jurkat T cells and upon leptin stimulation, the expression of early activation marker CD69 increases in a dose-dependent manner (0.1-10 nM). We have also found that leptin activates receptor-associated kinases of the Janus family-signal transucers and activators of transcription (JAK-STAT), mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase (PI3K) signalling pathways. Moreover, we sought to study the possible effect of leptin on cell survival and apoptosis of Jurkat T cells by culture in serum-free conditions. We have assayed the early phases of apoptosis by flow cytometric detection of fluorescein isothiocyanate (FITC)-labelled annexin V simultaneously with dye exclusion of propidium iodide (PI). As well, we have assayed the activation level of caspase-3 by inmunoblot with a specific antibody that recognizes active caspase-3. We have found that leptin inhibits the apoptotic process dose-dependently. By using pharmacological inhibitors, we have found that the stimulatory and anti-apoptotic effects of leptin in Jurkat T cells are dependent on MAPK activation, rather than the PI3K pathway, providing new data regarding the mechanism of action of leptin in T cells, which may be useful to understand more clearly the association between nutritional status and the immune function.
Collapse
Affiliation(s)
- P Fernández-Riejos
- Department of Clinical Biochemistry, Virgen Macarena University Hospital, Medical School University of Seville, Seville, Spain
| | | | | |
Collapse
|
34
|
Ge D, Gooljar SB, Kyriakou T, Collins LJ, Swaminathan R, Snieder H, Spector TD, O'Dell SD. Association of common JAK2 variants with body fat, insulin sensitivity and lipid profile. Obesity (Silver Spring) 2008; 16:492-6. [PMID: 18239666 PMCID: PMC2289869 DOI: 10.1038/oby.2007.79] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The leptin signal is transduced via the JAK2-STAT3 (Janus kinase 2-signal transducer and activator of transcription-3) pathway at the leptin receptor. JAK2 also phosphorylates insulin receptor substrate, integral to insulin and leptin action and is required for optimum adenosine triphosphate-binding cassette transporter A1 (ABCA1)-dependent transport of lipids from cells to apolipoprotein A-1 (apoA-I). We hypothesized that common variation in the JAK2 gene may be associated with body fat, insulin sensitivity, and modulation of the serum lipid profile in the general population. Ten tagging single-nucleotide polymorphisms (SNPs) spanning the gene were genotyped in 2,760 white female twin subjects (mean age 47.3 +/- 12.6 years) from the St Thomas' UK Adult Twin Registry. Minor allele frequencies were between 0.170 and 0.464. The major allele of rs7849191 was associated with higher central fat (P = 0.030), percentage of central fat (P = 0.014) and waist circumference (P = 0.027) the major allele of rs3780378 with higher serum apoA (P = 0.026), total cholesterol (P = 0.014), low-density lipoprotein (LDL) cholesterol (P = 0.012) and lower triglyceride (P = 0.023). However, no associations were significant at a level which took account of multiple testing. Although JAK2 is a critical element in leptin and insulin signaling and has a role in cellular cholesterol transport, we failed to establish associations of common SNPs with relevant phenotypes in this human study.
Collapse
Affiliation(s)
- Dongliang Ge
- Center for Population Genomics and Pharmacogenetics, Duke University, Durham, NC, USA
| | - Sakina B Gooljar
- Nutrition Food and Health Research Centre, King's College London, London, UK
| | - Theodosios Kyriakou
- Nutrition Food and Health Research Centre, King's College London, London, UK
| | - Laura J Collins
- Nutrition Food and Health Research Centre, King's College London, London, UK
| | | | - Harold Snieder
- Unit of Genetic Epidemiology and Bioinformatics, Department of Epidemiology, University Medical Center Groningen, University of Groningen, The Netherlands
- Twin Research and Genetic Epidemiology Unit, King's College London, St Thomas' Campus, London, UK
- Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, Georgia, USA
| | - Tim D Spector
- Twin Research and Genetic Epidemiology Unit, King's College London, St Thomas' Campus, London, UK
| | - Sandra D O'Dell
- Nutrition Food and Health Research Centre, King's College London, London, UK
- Address correspondence to Dr Sandra O'Dell, Nutrition Food and Health Research Centre, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK. sandra.o'
| |
Collapse
|
35
|
Li Z, Zhou Y, Carter-Su C, Myers MG, Rui L. SH2B1 enhances leptin signaling by both Janus kinase 2 Tyr813 phosphorylation-dependent and -independent mechanisms. Mol Endocrinol 2007; 21:2270-81. [PMID: 17565041 DOI: 10.1210/me.2007-0111] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Leptin controls body weight by activating its long form receptor (LEPRb). LEPRb binds to Janus kinase 2 (JAK2), a cytoplasmic tyrosine kinase that mediates leptin signaling. We previously reported that genetic deletion of SH2B1 (previously known as SH2-B), a JAK2-binding protein, results in severe leptin-resistant and obese phenotypes, indicating that SH2B1 is a key endogenous positive regulator of leptin sensitivity. Here we show that SH2B1 regulates leptin signaling by multiple mechanisms. In the absence of leptin, SH2B1 constitutively bound, via its non-SH2 domain region(s), to non-tyrosyl-phosphorylated JAK2, and inhibited JAK2. Leptin stimulated JAK2 phosphorylation on Tyr(813), which subsequently bound to the SH2 domain of SH2B1. Binding of the SH2 domain of SH2B1 to phospho-Tyr(813) in JAK2 enhanced leptin induction of JAK2 activity. JAK2 was required for leptin-stimulated phosphorylation of insulin receptor substrate 1 (IRS1), an upstream activator of the phosphatidylinositol 3-kinase pathway. Overexpression of SH2B1 enhanced both JAK2- and JAK2(Y813F)-mediated tyrosine phosphorylation of IRS1 in response to leptin, even though SH2B1 did not enhance JAK2(Y813F) activation. Leptin promoted the interaction of SH2B1 with IRS1. These data suggest that constitutive SH2B1-JAK2 interaction, mediated by the non-SH2 domain region(s) of SH2B1 and the non-Tyr(813) region(s) in JAK2, increases the local concentration of SH2B1 close to JAK2 and inhibits JAK2 activity. Leptin-stimulated SH2B1-JAK2 interaction, mediated by the SH2 domain of SH2B1 and phospho-Tyr(813) in JAK2, promotes JAK2 activation, thus globally enhancing leptin signaling. SH2B1-IRS1 interaction facilitates IRS1 phosphorylation by recruiting IRS1 to JAK2 and/or by protecting IRS1 from dephosphorylation, thus specifically enhancing leptin stimulation of the phosphatidylinositol 3-kinase pathway.
Collapse
Affiliation(s)
- Zhiqin Li
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0622, USA
| | | | | | | | | |
Collapse
|
36
|
Park S, Hong SM, Lee JE, Sung SR. Chlorpromazine exacerbates hepatic insulin sensitivity via attenuating insulin and leptin signaling pathway, while exercise partially reverses the adverse effects. Life Sci 2007; 80:2428-35. [PMID: 17512020 DOI: 10.1016/j.lfs.2007.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2006] [Revised: 02/20/2007] [Accepted: 04/09/2007] [Indexed: 12/23/2022]
Abstract
Investigated in this study are the effects and mechanisms of exercise and chlorpromazine (CPZ), a widely used conventional antipsychotic drug, on the hepatic insulin sensitivity of 90% pancreatectomized (Px) male Sprague-Dawley rats. The Px diabetic rats were provided with 0, 5, or 50 mg CPZ per kg of body weight (No-CPZ, LCPZ, or HCPZ) for 8 weeks, and half of each group had regular exercise. LCPZ did not exacerbate hepatic insulin sensitivity through insulin and leptin signaling in diabetic rats. However, HCPZ decreased whole-body glucose infusion rates in hyperinsulinemic clamped states, but not whole-body glucose uptake. This was due to the elevated hepatic glucose output in hyperinsulinemic states. The decreased hepatic insulin sensitivity was associated with insulin receptor substrate-2 (IRS2) protein levels in the liver. Decreased IRS2 levels attenuated hepatic insulin and leptin signaling pathways in hyperinsulinemic states, which elevated glucose production by inducing phosphoenolpyruvate carboxykinase expression. Long-term exercise recovered hepatic insulin sensitivity attenuated by HCPZ to reduce the hepatic glucose output in hyperinsulinemic clamped states. This recovery was related to enhanced insulin and leptin signaling via increased IRS2 gene and protein levels by activating the cAMP responding element-binding protein, but exercise improved only insulin signaling. In conclusion, HCPZ exacerbates hepatic insulin action by attenuating insulin and leptin signaling in type 2 diabetic rats, while regular exercise partially reverses the attenuation of hepatic insulin sensitivity by improving insulin signaling. Enhancement of insulin and leptin signaling through an induction of IRS2 may play an important role in improving hepatic glucose homeostasis.
Collapse
Affiliation(s)
- Sunmin Park
- Department of Food and Nutrition, College of Natural Science, Hoseo University, Asan-Si, Chungnam-Do, Republic of Korea.
| | | | | | | |
Collapse
|
37
|
Figueiredo D, Gertler A, Cabello G, Decuypere E, Buyse J, Dridi S. Leptin downregulates heat shock protein-70 (HSP-70) gene expression in chicken liver and hypothalamus. Cell Tissue Res 2007; 329:91-101. [PMID: 17406896 DOI: 10.1007/s00441-007-0414-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 03/07/2007] [Indexed: 11/30/2022]
Abstract
Heat shock protein (HSP)-70 is expressed in normal and stressed cells but is highly stress-inducible. Although leptin has long been suggested to be involved in the regulation of stress response, its interaction with the HSP-70 gene is still unknown, under both unstressed and stressed conditions. The present study has aimed to investigate the effect of leptin on HSP-70 gene expression in normal chicken liver, hypothalamus, and muscle. Continuous infusion of recombinant chicken leptin (8 mug/kg per hour) at a constant rate of 3 ml/h for 6 h in 3-week-old broiler chickens significantly (P < 0.05) decreased food intake and HSP-70 mRNA levels in liver and hypothalamus, but not in muscle. In an attempt to discriminate between the effect of leptin and of leptin-reduced food intake on HSP-70 gene expression, we also evaluated the effect of food deprivation on the same cellular responses in two broiler chicken lines genetically selected for low (LL) or high (FL) abdominal fat pad size. Food deprivation for 16 h did not affect HSP-70 gene expression in any of the studied tissues indicating that the effect of leptin was independent of the inhibition of food intake. Regardless of the nutritional status, HSP-70 mRNA levels were significantly (P < 0.05) higher in the hypothalamus of FL compared with LL chickens consistent with higher mRNA levels for hypothalamic corticotropin-releasing factor. To assess, whether the effects of leptin were direct or indirect, we carried out in vitro studies. Leptin treatments did not affect HSP-70 mRNA levels in a leghorn male hepatoma cell line or quail myoblast cell line suggesting that the effect of leptin on HSP-70 gene expression is mediated through the central nervous system. Furthermore, HSP-70 gene expression was gender-dependent with significantly (P < 0.05) higher levels in male than in female chickens.
Collapse
Affiliation(s)
- Denise Figueiredo
- Laboratory of Physiology, Immunology and Genetics of Domestic Animals, Catholic University of Leuven, 3001 Heverlee, Belgium
| | | | | | | | | | | |
Collapse
|
38
|
Mütze J, Roth J, Gerstberger R, Hübschle T. Nuclear translocation of the transcription factor STAT5 in the rat brain after systemic leptin administration. Neurosci Lett 2007; 417:286-91. [PMID: 17353091 DOI: 10.1016/j.neulet.2007.02.074] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Revised: 01/26/2007] [Accepted: 02/20/2007] [Indexed: 10/23/2022]
Abstract
Leptin binding to its functional receptor stimulates JAK-STAT-signaling pathway, which finally results in activation and nuclear translocation of transcription factors of the signal transducer and activator of transcription (STAT) family, namely of STAT3. Here we report for the first time that systemic treatment with leptin (5 mg/kg; intraperitoneal injection) also increased the number of nuclear STAT5 signals in the hypothalamus. In particular, the entire arcuate nucleus (ARC), the ventral premammilary nucleus (PMV), and the supraoptic nucleus (SO) showed an enhanced nuclear STAT5 translocation in response to leptin when compared to saline, 120 min after the respective injection. Co-localization studies revealed that a high percentage of those STAT5-responsive cells proved to be neurons. In addition, some astrocytes within the ARC showed nuclear STAT5 signals. The functional relevance of leptin-induced nuclear STAT5 activation in hypothalamic cells still has to be determined.
Collapse
Affiliation(s)
- Jörg Mütze
- Department of Veterinary-Physiology, Justus-Liebig-University Giessen, Frankfurter Strasse 100, D-35392 Giessen, Germany
| | | | | | | |
Collapse
|
39
|
Bełtowski J, Wójcicka G, Jamroz-Wiśniewska A, Borkowska E. Role of PI3K and PKB/Akt in acute natriuretic and NO-mimetic effects of leptin. ACTA ACUST UNITED AC 2007; 140:168-77. [PMID: 17229473 DOI: 10.1016/j.regpep.2006.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Revised: 11/27/2006] [Accepted: 12/01/2006] [Indexed: 10/23/2022]
Abstract
Apart from controlling energy balance, leptin, a peptide hormone secreted by white adipose tissue, is also involved in the regulation of cardiovascular function. Previous studies have documented that leptin stimulates natriuresis and nitric oxide (NO) production, but the mechanism of these effects is incompletely elucidated. We examined whether phosphoinositide 3-kinase (PI3K) and its downstream effector, protein kinase B/Akt are involved in acute natriuretic and NO-mimetic effects of leptin in anaesthetized rats. Leptin (1 mg/kg i.v.) induced a marked increase in natriuresis and this effect was abolished by pretreatment with either wortmannin (15 microg/kg) or LY294002 (0.6 mg/kg), two structurally different PI3K inhibitors. Moreover, leptin increased plasma concentration and urinary excretion of NO metabolites, nitrites+nitrates (NO(x)), and of NO second messenger, cyclic GMP. In addition, leptin increased NO(x) and cGMP in aortic tissue. The stimulatory effect of leptin on NO(x) and cGMP was prevented by PKB/Akt inhibitor, triciribine, but not by either wortmannin or LY294002. Triciribine had no effect on leptin-induced natriuresis. Leptin stimulated Akt phosphorylation at Ser(473) in aortic tissue but not in the kidney. These results suggest that leptin-induced natriuresis is mediated by PI3K but not Akt, whereas NO-mimetic effect of leptin results from PI3K-independent stimulation of Akt.
Collapse
Affiliation(s)
- Jerzy Bełtowski
- Department of Pathophysiology, Medical University, ul. Jaczewskiego 8, 20-090 Lublin, Poland.
| | | | | | | |
Collapse
|
40
|
Maures TJ, Kurzer JH, Carter-Su C. SH2B1 (SH2-B) and JAK2: a multifunctional adaptor protein and kinase made for each other. Trends Endocrinol Metab 2007; 18:38-45. [PMID: 17140804 DOI: 10.1016/j.tem.2006.11.007] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Revised: 11/13/2006] [Accepted: 11/20/2006] [Indexed: 12/28/2022]
Abstract
Src homology 2 (SH2) B adaptor protein 1 (SH2B1; originally named SH2-B) is a member of a family of adaptor proteins that influences a variety of signaling pathways mediated by Janus kinase (JAK) and receptor tyrosine kinases. Although SH2B1 performs classical adaptor functions, such as recruitment of specific proteins to activated receptors, it also demonstrates a unique ability to enhance the kinase activity of the cytokine receptor-associated tyrosine kinase JAK2, as well as that of several receptor tyrosine kinases. SH2B1 is also among a small number of adaptor proteins shown to undergo nucleocytoplasmic shuttling, although its exact role within the nucleus is not yet clear. Deletion of the SH2B1 gene results in severe obesity and both leptin and insulin resistance, as well as infertility, which might be a consequence of resistance to insulin-like growth factor I. Thus, knockout mice support a role for SH2B1 as a positive regulator of JAK2 signaling pathways initiated by leptin, as well as of pathways initiated by insulin and, potentially, by insulin-like growth factor I.
Collapse
Affiliation(s)
- Travis J Maures
- Graduate Program in Cellular and Molecular Biology, University of Michigan Medical School, Ann Arbor, MI 48109-0662, USA
| | | | | |
Collapse
|
41
|
Huypens PR. Leptin and adiponectin regulate compensatory beta cell growth in accordance to overweight. Med Hypotheses 2006; 68:1134-7. [PMID: 17098372 DOI: 10.1016/j.mehy.2006.09.046] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2006] [Accepted: 09/12/2006] [Indexed: 12/31/2022]
Abstract
Compensatory beta cell growth occurs in accordance to overweight and increasing insulin demands. The proliferative actions of insulin and insulin-like growth factors are mediated via the IRS-2-PI(3)K-Akt pathway of pleiotropic insulin signaling. However, sustained activation leads to negative feedback via the mTOR-induced proteasomal degradation of IRS-2. The proliferative actions of incretins and adipokines are mediated via other pathways that ultimately converge with the IRS-2-PI(3)K-Akt axis. The incretins GIP and GLP-1 increase IRS-2 levels in beta cells by acting via the cAMP-PKA pathway, whereas leptin inhibits PTEN activity via CK2-dependent pathways. By increasing PIP(3) availability the adipokine amplifies the magnitude as well as duration of factors acting via the IRS-2-PI(3)K-Akt pathway. Considering that AMPK prevents mTOR-induced degradation of IRS-2, we propose that adiponectin and leptin cooperatively achieve compensatory beta cell growth in accordance to adiposity. In conditions of overt obesity, when adiponectin levels are too low to provide sufficient IRS-2 levels, loss of compensatory beta cell growth may occur.
Collapse
|
42
|
Jamshidi Y, Snieder H, Wang X, Pavitt MJ, Spector TD, Carter ND, O’Dell SD. Phosphatidylinositol 3-kinase p85alpha regulatory subunit gene PIK3R1 haplotype is associated with body fat and serum leptin in a female twin population. Diabetologia 2006; 49:2659-67. [PMID: 17016694 PMCID: PMC1626353 DOI: 10.1007/s00125-006-0388-z] [Citation(s) in RCA: 18] [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: 04/06/2006] [Accepted: 06/18/2006] [Indexed: 11/28/2022]
Abstract
AIMS/HYPOTHESIS Phosphatidylinositol 3-kinase (PI3K) couples the leptin and insulin signalling pathways via the insulin receptor substrates IRS1 and IRS2. Hence, defective activation of PI3K could be a novel mechanism of peripheral leptin or insulin resistance. We investigated associations of tagging single-nucleotide polymorphisms (tSNPs) in the PI3K p85alpha regulatory subunit gene PIK3R1 with anthropometry, leptin, body fat and insulin sensitivity in a female twin population of European extraction. MATERIALS AND METHODS Eight tSNPs were genotyped in 2,778 women (mean age 47.4+/-12.5 years) from the St Thomas' UK Adult Twin Registry (Twins UK). RESULTS SNP rs1550805 was associated with serum leptin (p=0.028), BMI (p=0.025), weight (p=0.019), total fat (p=0.004), total fat percentage (p=0.002), waist circumference (p=0.025), central fat (p=0.005) and central fat percentage (p=0.005). SNPs rs7713645 and rs7709243 were associated with BMI (p=0.020 and p=0.029, respectively), rs7709243 with weight, total and central fat (p=0.026, p=0.031 and p=0.023, respectively) and both SNPs with fasting glucose (p=0.003 and p=0.001, respectively) and glucose 2-h post OGTT (p=0.023 and p=0.007, respectively). Subjects with haplotype 222 (frequency 7.2%) showed higher serum leptin concentration (p=0.007) and body fat measures (p< or =0.001 for all), and those with haplotype 221 (frequency 38.7%) showed higher fasting and 2-h glucose (p=0.035 and p=0.021, respectively) compared with subjects with the most common haplotype, 111 (frequency 45.5%). CONCLUSIONS/INTERPRETATION Association of the PIK3R1 SNP rs1550805 with serum leptin and body fat may reflect a diminished ability of PI3K to signal via IRS1 or IRS2 in response to leptin.
Collapse
Affiliation(s)
- Y. Jamshidi
- Department of Clinical Developmental Sciences, St George’s University of London, UK
| | - H. Snieder
- Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, GA, USA
- Twin Research and Genetic Epidemiology Unit, St Thomas’ Hospital, London, UK
| | - X. Wang
- Georgia Prevention Institute, Department of Pediatrics, Medical College of Georgia, Augusta, GA, USA
| | - M. J. Pavitt
- Department of Clinical Developmental Sciences, St George’s University of London, UK
| | - T. D. Spector
- Twin Research and Genetic Epidemiology Unit, St Thomas’ Hospital, London, UK
| | - N. D. Carter
- Department of Clinical Developmental Sciences, St George’s University of London, UK
| | - S. D. O’Dell
- Nutrition Food and Health Research Centre, King’s College London, UK
- Address correspondence to Dr Sandra O’Dell, Nutrition Food and Health Research Centre, King’s College London, Franklin-Wilkins Building, 150 Stamford Street, London SE1 9NH, UK. Tel: +44 (0)20 7848 3177, Fax: +44 (0)20 7848 4185, sandra.o’
| |
Collapse
|
43
|
Flores MBS, Fernandes MFA, Ropelle ER, Faria MC, Ueno M, Velloso LA, Saad MJA, Carvalheira JBC. Exercise improves insulin and leptin sensitivity in hypothalamus of Wistar rats. Diabetes 2006; 55:2554-61. [PMID: 16936204 DOI: 10.2337/db05-1622] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Prolonged exercise of medium to high intensity is known to promote a substantial effect on the energy balance of rats. In male rats, moderately to severely intense programs lead to a reduction in food intake. However, the exact causes for the appetite-suppressive effects of exercise are not known. Here, we show that intracerebroventricular insulin or leptin infusion reduced food intake in exercised rats to a greater extent than that observed in control animals. Exercise was associated with a markedly increased phosphorylation/activity of several proteins involved in leptin and insulin signal transduction in the hypothalamus. The regulatory role of interleukin (IL)-6 in mediating the increase in leptin and insulin sensitivity in hypothalamus was also investigated. Treatment with insulin or leptin markedly reduced food intake in exercised rats that were pretreated with vehicle, although no increase in sensitivity to leptin- and insulin-induced anorexia after pretreatment with anti-IL-6 antibody was detected. The current study provides direct measurements of leptin and insulin signaling in the hypothalamus and documents increased sensitivity to these hormones in the hypothalamus of exercised rats in an IL-6-dependent manner. These findings provide support for the hypothesis that the appetite-suppressive actions of exercise may be mediated by the hypothalamus.
Collapse
Affiliation(s)
- Marcelo B S Flores
- Department of Internal Medicine, State University of Campinas (UNICAMP), 13081-970-Campinas, SP, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
44
|
Tups A, Helwig M, Stöhr S, Barrett P, Mercer JG, Klingenspor M. Photoperiodic regulation of insulin receptor mRNA and intracellular insulin signaling in the arcuate nucleus of the Siberian hamster,Phodopus sungorus. Am J Physiol Regul Integr Comp Physiol 2006; 291:R643-50. [PMID: 16601260 DOI: 10.1152/ajpregu.00807.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During the last 5 years it has been well established that photoperiod-induced changes in body weight in the seasonal hamster, Phodopus sungorus, are accompanied by a marked seasonal cycle in leptin sensitivity. In the present study, we investigated the possible involvement of insulin signaling in seasonal body weight regulation. We analyzed the expression pattern and relative intensity of insulin receptor (IR), phosphatidylinositol 3-kinase (PI3-kinase), and protein tyrosine phosphatase 1B (PTP1B) mRNAs by in situ hybridization in the brains of juvenile female hamsters acclimated to either long- (LD) or short-day length (SD) for 8 wk, with or without superimposed food deprivation for 48 h. Furthermore, the hypothalamic concentration and distribution of phospho-AKT, a marker of PI3-kinase activity was determined by immunoblotting and immunohistochemistry. Eight weeks of acclimation to SD led to a substantial downregulation of IR, PTP1B gene expression, and phospho-AKT concentration in this brain region, whereas PI3-kinase mRNA was unchanged. Food deprivation induced a decrease in PTP1B and a trend toward lowered IR gene expression in LD but not in SD. Additionally, a striking increase in PTP1B gene expression in the thalamus was observed after food deprivation in both photoperiods. The direction of change in neuronal insulin signaling contrasts to the central catabolic nature of this pathway described in other species. SD-induced reduction in insulin signaling may be due to decline in body fat stores mediated by enhanced central leptin sensitivity. Increased anorexigenic tone of leptin may overwrite central insulin signaling to prevent catabolic overdrive.
Collapse
Affiliation(s)
- Alexander Tups
- Division of Obesity and Metabolic Health, Rowett Research Institute, Aberdeen Centre for Energy Regulation and Obesity, Scotland.
| | | | | | | | | | | |
Collapse
|
45
|
Wei Y, Wang D, Topczewski F, Pagliassotti MJ. Fructose-mediated stress signaling in the liver: implications for hepatic insulin resistance. J Nutr Biochem 2006; 18:1-9. [PMID: 16854579 DOI: 10.1016/j.jnutbio.2006.03.013] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2006] [Revised: 03/14/2006] [Accepted: 03/30/2006] [Indexed: 02/08/2023]
Abstract
Organisms reprogram metabolic pathways to adapt to changes in nutrient availability. This requires that nutrient-based stimuli are sensed, signals are transmitted, and highly specific responses are engaged. We propose that in the liver, the mitogen-activated protein kinase, c-jun N-terminal kinase (JNK), links excessive nutrient metabolism with impaired insulin regulation of glucose production. The liver, by virtue of its anatomic position and selective regulatory features, buffers and is highly responsive to changes in nutrient delivery. In particular, sugars such as sucrose and fructose uniquely regulate and are selectively metabolized by the liver. We propose that when hepatic fructose uptake exceeds requirements for glycogen and energy (hepatic sugar excess), the JNK-signaling pathway is engaged as part of the adaptive response.
Collapse
Affiliation(s)
- Yuren Wei
- Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, CO 80523, USA
| | | | | | | |
Collapse
|
46
|
Velloso LA. [The hypothalamic control of feeding and thermogenesis: implications on the development of obesity]. ACTA ACUST UNITED AC 2006; 50:165-76. [PMID: 16767283 DOI: 10.1590/s0004-27302006000200003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The worldwide increase in the prevalence of obesity is becoming one of the most important clinical-epidemiological phenomena of the present days. Environmental factors such as changes in life-style and feeding behavior associated with poorly characterized genetic determinants are though to play the most important roles in the pathogenesis of this disease. During the last ten years, since the discovery of leptin, great advances were obtained in the characterization of the hypothalamic mechanisms involved in the control of food intake and thermogenesis. Such advances are unveiling a complex and integrated system and are opening a wide perspective for the finding of novel therapeutic targets for the treatment of this harming condition. This review will present some of the most recent findings in this field. It will be focused on the actions of leptin and insulin in the hypothalamus and will explore the hypothesis that hypothalamic resistance to the action of these hormones may play a role in the development of obesity and may act as a molecular link between obesity, type 2 diabetes mellitus and other clinical conditions on which insulin resistance plays an important pathogenetic role.
Collapse
|
47
|
Carvalheira JBC, Saad MJA. [Insulin resistance/hyperinsulinemia associated diseases not included in the metabolic syndrome]. ARQUIVOS BRASILEIROS DE ENDOCRINOLOGIA E METABOLOGIA 2006; 50:360-7. [PMID: 16767302 DOI: 10.1590/s0004-27302006000200022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In the past years, in Brazil and in developed countries, obesity has become a major public health problem. It was identified that besides DM2 and metabolic syndrome other clinical entities were associated with insulin resistance. In this review we describe some of these alterations emphasizing nonalcoholic fatty liver disease, but also including polycistic ovary disease, hyperuricemia, chronic renal failure, heart failure, cognitive decline and cancer.
Collapse
|
48
|
Benomar Y, Roy AF, Aubourg A, Djiane J, Taouis M. Cross down-regulation of leptin and insulin receptor expression and signalling in a human neuronal cell line. Biochem J 2005; 388:929-39. [PMID: 15715521 PMCID: PMC1183474 DOI: 10.1042/bj20041621] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Leptin and insulin are major signals to the hypothalamus to regulate energy homoeostasis and body adiposity. IR (insulin receptors) and leptin receptors (long isoform, ObRb) share a number of signalling cascades, such as JAK2/STAT-3 (Janus kinase 2/signal transduction and activator of transcription 3) and PI3K (phosphoinositide 3-kinase); the cross-talk between IR and ObRb have been described previously in non-neuronal cells. Differentiated human neuroblastoma (SH-SY5Y) cells express endogenous ObR and IR, and respond to leptin and insulin with stimulation of STAT-3 and MAPK (mitogen-activated protein kinase) phosphorylation, and PI3K activity. Insulin or leptin pre-treatment of SH-SY5Y cells increased basal STAT-3 phosphorylation, but abolished the acute effect of these hormones, and, interestingly, leptin pre-treatment abolished insulin effect and vice versa. Similar results were obtained for MAPK phosphorylation, but leptin or insulin pre-treatment did not completely abolish the acute effect of insulin or leptin. We have also showed that insulin and leptin are able to activate PI3K through IRS-1 (insulin receptor substrate 1) and IRS-2 respectively. Furthermore, leptin or insulin pre-treatment increased basal PI3K activity and IRS-1 or IRS-2 association with p85 and abolished acute insulin or leptin effect, in addition to the down-regulation of IRS-1 and IRS-2. Finally, insulin pre-treatment reduced leptin binding by approx. 60%, and leptin pre-treatment reduced the expression of insulin receptor by 40% in SH-SY5Y cells, which most likely accounts for the cross down-regulation of leptin and insulin receptors. These results provide evidence to suggest cross down-regulation of leptin and insulin receptors at both receptor and downstream signalling levels. This finding may contribute to the understanding of the complex relationship between leptin resistance and insulin resistance at the neuronal level.
Collapse
Affiliation(s)
- Yacir Benomar
- Neuroendocrinologie Moléculaire de la Prise Alimentaire, Laboratoire d'Endocrinologie de la Nutrition, INRA, Université Paris XI, IBAIC Bat. 447, Orsay 91405, France
| | - Anne-France Roy
- Neuroendocrinologie Moléculaire de la Prise Alimentaire, Laboratoire d'Endocrinologie de la Nutrition, INRA, Université Paris XI, IBAIC Bat. 447, Orsay 91405, France
| | - Alain Aubourg
- Neuroendocrinologie Moléculaire de la Prise Alimentaire, Laboratoire d'Endocrinologie de la Nutrition, INRA, Université Paris XI, IBAIC Bat. 447, Orsay 91405, France
| | - Jean Djiane
- Neuroendocrinologie Moléculaire de la Prise Alimentaire, Laboratoire d'Endocrinologie de la Nutrition, INRA, Université Paris XI, IBAIC Bat. 447, Orsay 91405, France
| | - Mohammed Taouis
- Neuroendocrinologie Moléculaire de la Prise Alimentaire, Laboratoire d'Endocrinologie de la Nutrition, INRA, Université Paris XI, IBAIC Bat. 447, Orsay 91405, France
- To whom correspondence should be addressed (email )
| |
Collapse
|
49
|
Ren D, Li M, Duan C, Rui L. Identification of SH2-B as a key regulator of leptin sensitivity, energy balance, and body weight in mice. Cell Metab 2005; 2:95-104. [PMID: 16098827 DOI: 10.1016/j.cmet.2005.07.004] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2005] [Revised: 05/17/2005] [Accepted: 07/20/2005] [Indexed: 12/12/2022]
Abstract
Leptin regulates energy balance and body weight by activating its receptor LEPRb and multiple downstream signaling pathways, including the STAT3 and the IRS2/PI 3-kinase pathways, in the hypothalamus. Leptin stimulates activation of LEPRb-associated JAK2, which initiates cell signaling. Here we identified SH2-B, a JAK2-interacting protein, as a key regulator of leptin sensitivity, energy balance, and body weight. SH2-B homozygous null mice were severely hyperphagic and obese and developed a metabolic syndrome characterized by hyperleptinemia, hyperinsulinemia, hyperlipidemia, hepatic steatosis, and hyperglycemia. The expression of hypothalamic orexigenic NPY and AgRP was increased in SH2-B(-/-) mice. Leptin-stimulated activation of hypothalamic JAK2 and phosphorylation of hypothalamic STAT3 and IRS2 were significantly impaired in SH2-B(-/-) mice. Moreover, overexpression of SH2-B counteracted PTP1B-mediated inhibition of leptin signaling in cultured cells. Our data suggest that SH2-B is an endogenous enhancer of leptin sensitivity and required for maintaining normal energy metabolism and body weight in mice.
Collapse
Affiliation(s)
- Decheng Ren
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | | | | | | |
Collapse
|
50
|
Ferraroni NR, Geloneze B, Mansour E, Perroud AP, Muscelli EO, Tambascia M, de Lima Zollner R, Velloso LA. Severe hypoleptinaemia associated with insulin resistance in patients with common variable immunodeficiency. Clin Endocrinol (Oxf) 2005; 63:63-5. [PMID: 15963063 DOI: 10.1111/j.1365-2265.2005.02300.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Common variable immunodeficiency (CVI) is a primary immunodeficiency syndrome characterized by impaired production of antibodies and recurrent infections. Delay in diagnosis leads to metabolic wastage and low body weight. Leptin, a hormone produced by white adipose tissue, modulates insulin action by signal transduction cross-talk and by direct action on pancreatic beta-cells. We hypothesized that patients with CVI might present a defective regulation of leptin production and insulin resistance. PATIENTS Thirteen CVI patients (39 +/- 11 years) under gammaglobulin replacement were evaluated in parallel with 13 gender-, age-, body weight- and body mass index (BMI)-matched healthy voluntaries, and with data from two large population series, the Bruneck and the Hoorn Studies. MEASUREMENTS Serum leptin and insulin levels, homeostasis model assessment - insulin resistance (HOMA-IR), body composition, haematological, biochemical and immunoglobulin measurements were obtained. Data were analysed by a one-way analysis of variance (anova) and by Pearson's rank analysis. The institutional ethics committee approved the study, and informed consent was obtained from patients and controls. RESULTS No differences were found between CVI and the control group when comparing gender distribution, age, body weight, BMI, waist/hip ratio, relative body fat and fasting glucose levels. Leptin levels were lower (P < 0.05) in CVI patients than in controls and lower than fasting leptin levels detected in a large population study. CVI patients' serum leptin levels did not correlate with BMI (r = 0.074, P = 0.8) and their high HOMA-IR indicated insulin resistance. CONCLUSIONS CVI patients are relatively hypoleptinaemic and insulin resistant, and their serum leptin levels are not correlated to their BMI.
Collapse
|