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Li Z, Liu Q, Cai Y, Ye N, He Z, Yao Y, Ding Y, Wang P, Qi C, Zheng L, Wang L, Zhou J, Zhang QQ. EPAC inhibitor suppresses angiogenesis and tumor growth of triple-negative breast cancer. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167114. [PMID: 38447883 DOI: 10.1016/j.bbadis.2024.167114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 02/29/2024] [Accepted: 03/01/2024] [Indexed: 03/08/2024]
Abstract
AIMS Exchange protein directly activated by cAMP 1 (EPAC1), a major isoform of guanine nucleotide exchange factors, is highly expressed in vascular endothelia cells and regulates angiogenesis in the retina. High intratumor microvascular densities (MVD) resulting from angiogenesis is responsible for breast cancer development. Downregulation of EPAC1 in tumor cell reduces triple-negative breast cancer (TNBC)-induced angiogenesis. However, whether Epac1 expressed in vascular endothelial cells contributes to angiogenesis and tumor development of TNBC remains elusive. MAIN METHODS We employed NY0123, a previously identified potent EPAC inhibitor, to explore the anti-angiogenic biological role of EPAC1 in vitro and in vivo through vascular endothelial cells, rat aortic ring, Matrigel plug, and chick embryo chorioallantoic membrane (CAM) and yolk sac membrane (YSM) assays, as well as the in vivo xenograft tumor models of TNBC in both chick embryo and mice. KEY FINDINGS Inhibiting EPAC1 in vascular endothelial cells by NY0123 significantly suppresses angiogenesis and tumor growth of TNBC. In addition, NY0123 possesses a better inhibitory efficacy than ESI-09, a reported specific EPAC inhibitor tool compound. Importantly, inhibiting EPAC1 in vascular endothelia cells regulates the typical angiogenic signaling network, which is associated with not only vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor-2 (VEGFR2) signaling, but also PI3K/AKT, MEK/ERK and Notch pathway. CONCLUSIONS Our findings support that EPAC1 may serve as an effective anti-angiogenic therapeutic target of TNBC, and EPAC inhibitor NY0123 has the therapeutic potential to be developed for the treatment of TNBC.
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Affiliation(s)
- Zishuo Li
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Qiao Liu
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yuhao Cai
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Na Ye
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Zinan He
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yuying Yao
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Yi Ding
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Pingyuan Wang
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Cuiling Qi
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Lingyun Zheng
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Lijing Wang
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China
| | - Jia Zhou
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States.
| | - Qian-Qian Zhang
- School of Basic Medical Sciences, Guangdong Pharmaceutical University, Guangzhou 510006, China.
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2
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Rosen ED. EPAC1 boosts thermogenic adipocyte formation. Nat Cell Biol 2024; 26:39-40. [PMID: 38195706 DOI: 10.1038/s41556-023-01304-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2024]
Affiliation(s)
- Evan D Rosen
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA, USA.
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3
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Genchi VA, Palma G, Sorice GP, D'Oria R, Caccioppoli C, Marrano N, Biondi G, Caruso I, Cignarelli A, Natalicchio A, Laviola L, Giorgino F, Perrini S. Pharmacological modulation of adaptive thermogenesis: new clues for obesity management? J Endocrinol Invest 2023; 46:2213-2236. [PMID: 37378828 PMCID: PMC10558388 DOI: 10.1007/s40618-023-02125-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023]
Abstract
BACKGROUND Adaptive thermogenesis represents the main mechanism through which the body generates heat in response to external stimuli, a phenomenon that includes shivering and non-shivering thermogenesis. The non-shivering thermogenesis is mainly exploited by adipose tissue characterized by a brown aspect, which specializes in energy dissipation. A decreased amount of brown adipose tissue has been observed in ageing and chronic illnesses such as obesity, a worldwide health problem characterized by dysfunctional adipose tissue expansion and associated cardiometabolic complications. In the last decades, the discovery of a trans-differentiation mechanism ("browning") within white adipose tissue depots, leading to the generation of brown-like cells, allowed to explore new natural and synthetic compounds able to favour this process and thus enhance thermogenesis with the aim of counteracting obesity. Based on recent findings, brown adipose tissue-activating agents could represent another option in addition to appetite inhibitors and inhibitors of nutrient absorption for obesity treatment. PURPOSE This review investigates the main molecules involved in the physiological (e.g. incretin hormones) and pharmacological (e.g. β3-adrenergic receptors agonists, thyroid receptor agonists, farnesoid X receptor agonists, glucagon-like peptide-1, and glucagon receptor agonists) modulation of adaptive thermogenesis and the signalling mechanisms involved.
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Affiliation(s)
- V A Genchi
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - G Palma
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - G P Sorice
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - R D'Oria
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - C Caccioppoli
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - N Marrano
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - G Biondi
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - I Caruso
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - A Cignarelli
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - A Natalicchio
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - L Laviola
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
| | - F Giorgino
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy.
| | - S Perrini
- Section of Internal Medicine, Endocrinology, Andrology and Metabolic Diseases, Department of Precision and Regenerative Medicine and Ionian Area, University of Bari Aldo Moro, Piazza Giulio Cesare, 11, 70124, Bari, Italy
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4
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Ma Z, Wang W, Zhang D, Zhang Y, Zhao Y, Li X, Zhao L, Lin C, Wang J, Zhou B, Cheng J, Xu D, Li W, Yang X, Huang Y, Cui P, Liu J, Zeng X, Zhai R, Zhang X. Ovine RAP1GAP and rBAT gene polymorphisms and their association with tail fat deposition in Hu sheep. Front Vet Sci 2022; 9:974513. [PMID: 36090178 PMCID: PMC9453205 DOI: 10.3389/fvets.2022.974513] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
Excessive fat deposition in the tail of sheep will affect its feed efficiency, which will increase the feeding cost. The purpose of this study was to identify the single nucleotide polymorphisms (SNPs) of RAP1GAP and rBAT genes by PCR amplification and Sanger sequencing, the SNPs were genotyped by KASP genotyping assays to evaluate their association with tail fat deposition traits. The results showed that two intronic mutations of g.13561 G > A and g.1460 T > C were found in RAP1GAP and rBAT, respectively. There were three genotypes of GG, AG, AA and CC, CT and TT at these two loci, respectively. Association analysis showed that g.13561 G > A of RAP1GAP was associated with tail width, tail fat weight and relative tail fat weight (P < 0.05). The g.1460 T > C of rBAT was associated with tail width and tail fat weight (P < 0.05). Different combinations of genotypes also differed significantly with tail fat deposition traits. In the tail fat tissue, the expression levels of RAP1GAP gene was significantly higher in small-tailed sheep than in big-tailed sheep, and the expression levels of rBAT gene was significantly higher in big-tailed sheep than in small-tailed sheep. In the liver, the expression levels of RAP1GAP and rBAT gene was significantly higher at 6 months than at 0 and 3 months. In conclusion, RAP1GAP and rBAT polymorphisms can be used as a candidate molecular marker to reduce tail fat deposition in sheep.
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Affiliation(s)
- Zongwu Ma
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Weimin Wang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
- The State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
| | - Deyin Zhang
- The State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
| | - Yukun Zhang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Yuan Zhao
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Xiaolong Li
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Liming Zhao
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Changchun Lin
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Jianghui Wang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Bubo Zhou
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Jiangbo Cheng
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Dan Xu
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Wenxin Li
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Xiaobin Yang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Yongliang Huang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Panpan Cui
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Jia Liu
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Xiwen Zeng
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Rui Zhai
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
| | - Xiaoxue Zhang
- College of Animal Science and Technology, Gansu Agricultural University, Lanzhou, China
- *Correspondence: Xiaoxue Zhang
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5
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Liu J, Lai F, Hou Y, Zheng R. Leptin signaling and leptin resistance. MEDICAL REVIEW (BERLIN, GERMANY) 2022; 2:363-384. [PMID: 37724323 PMCID: PMC10388810 DOI: 10.1515/mr-2022-0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 07/12/2022] [Indexed: 09/20/2023]
Abstract
With the prevalence of obesity and associated comorbidities, studies aimed at revealing mechanisms that regulate energy homeostasis have gained increasing interest. In 1994, the cloning of leptin was a milestone in metabolic research. As an adipocytokine, leptin governs food intake and energy homeostasis through leptin receptors (LepR) in the brain. The failure of increased leptin levels to suppress feeding and elevate energy expenditure is referred to as leptin resistance, which encompasses complex pathophysiological processes. Within the brain, LepR-expressing neurons are distributed in hypothalamus and other brain areas, and each population of the LepR-expressing neurons may mediate particular aspects of leptin effects. In LepR-expressing neurons, the binding of leptin to LepR initiates multiple signaling cascades including janus kinase (JAK)-signal transducers and activators of transcription (STAT) phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT), extracellular regulated protein kinase (ERK), and AMP-activated protein kinase (AMPK) signaling, etc., mediating leptin actions. These findings place leptin at the intersection of metabolic and neuroendocrine regulations, and render leptin a key target for treating obesity and associated comorbidities. This review highlights the main discoveries that shaped the field of leptin for better understanding of the mechanism governing metabolic homeostasis, and guides the development of safe and effective interventions to treat obesity and associated diseases.
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Affiliation(s)
- Jiarui Liu
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Futing Lai
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Yujia Hou
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
| | - Ruimao Zheng
- Department of Anatomy, Histology and Embryology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China
- Neuroscience Research Institute, Peking University, Beijing, China
- Key Laboratory for Neuroscience of Ministry of Education, Peking University, Beijing, China
- Key Laboratory for Neuroscience of National Health Commission, Peking University, Beijing 100191, China
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6
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Kaneko K, Takekuma Y, Goto T, Ohinata K. An orally active plant Rubisco-derived peptide increases neuronal leptin responsiveness. Sci Rep 2022; 12:8599. [PMID: 35597815 PMCID: PMC9124197 DOI: 10.1038/s41598-022-12595-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/13/2022] [Indexed: 11/25/2022] Open
Abstract
Nutrient excess, such as the intake of a high-fat diet, reduces hypothalamic responses to exogenously administered leptin and induces dietary obesity; however, orally active components that attenuate neural leptin dysregulation have yet to be identified. We herein demonstrated that YHIEPV, derived from the pepsin-pancreatin digestion of the green leaf protein Rubisco, increased the leptin-induced phosphorylation of STAT3 in ex vivo hypothalamic slice cultures. We also showed that YHIEPV mitigated palmitic acid-induced decreases in leptin responsiveness. Furthermore, orally administered YHIEPV promoted leptin-induced reductions in body weight and food intake in obese mice. In addition, dietary-induced body weight gain was significantly less in mice orally or centrally administered YHIEPV daily than in saline-control mice. Cellular leptin sensitivity and the levels of proinflammatory-related factors, such as IL1β and Socs-3, in the hypothalamus of obese mice were also restored by YHIEPV. YHIEPV blocked cellular leptin resistance induced by forskolin, which activates Epac-Rap1 signaling, and reduced the level of the GTP-bound active form of Rap1 in the brains of obese mice. Collectively, the present results demonstrated that the orally active peptide YHIEPV derived from a major green leaf protein increased neural leptin responsiveness and reduced body weight gain in mice with dietary obesity.
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Affiliation(s)
- Kentaro Kaneko
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan. .,Department of Agricultural Chemistry, School of Agriculture, Meiji University, 1-1-1, Higashimita, Tama-ku, Kawasaki-shi, Kanagawa, 214-8571, Japan.
| | - Yukihiro Takekuma
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
| | - Tsuyoshi Goto
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
| | - Kousaku Ohinata
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
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PDE4D targeting enhances anti-tumor effects of sorafenib in clear cell renal cell carcinoma and attenuates MAPK/ERK signaling in a CRAF-dependent manner. Transl Oncol 2022; 19:101377. [PMID: 35196602 PMCID: PMC8866901 DOI: 10.1016/j.tranon.2022.101377] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/15/2022] [Indexed: 01/16/2023] Open
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8
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Valentine JM, Ahmadian M, Keinan O, Abu-Odeh M, Zhao P, Zhou X, Keller MP, Gao H, Yu RT, Liddle C, Downes M, Zhang J, Lusis AJ, Attie AD, Evans RM, Rydén M, Saltiel AR. β3-Adrenergic receptor downregulation leads to adipocyte catecholamine resistance in obesity. J Clin Invest 2022; 132:e153357. [PMID: 34847077 PMCID: PMC8759781 DOI: 10.1172/jci153357] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 11/17/2021] [Indexed: 11/17/2022] Open
Abstract
The dysregulation of energy homeostasis in obesity involves multihormone resistance. Although leptin and insulin resistance have been well characterized, catecholamine resistance remains largely unexplored. Murine β3-adrenergic receptor expression in adipocytes is orders of magnitude higher compared with that of other isoforms. While resistant to classical desensitization pathways, its mRNA (Adrb3) and protein expression are dramatically downregulated after ligand exposure (homologous desensitization). β3-Adrenergic receptor downregulation also occurs after high-fat diet feeding, concurrent with catecholamine resistance and elevated inflammation. This downregulation is recapitulated in vitro by TNF-α treatment (heterologous desensitization). Both homologous and heterologous desensitization of Adrb3 were triggered by induction of the pseudokinase TRIB1 downstream of the EPAC/RAP2A/PI-PLC pathway. TRIB1 in turn degraded the primary transcriptional activator of Adrb3, CEBPα. EPAC/RAP inhibition enhanced catecholamine-stimulated lipolysis and energy expenditure in obese mice. Moreover, adipose tissue expression of genes in this pathway correlated with body weight extremes in a cohort of genetically diverse mice and with BMI in 2 independent cohorts of humans. These data implicate a signaling axis that may explain reduced hormone-stimulated lipolysis in obesity and resistance to therapeutic interventions with β3-adrenergic receptor agonists.
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Affiliation(s)
| | | | | | | | | | - Xin Zhou
- Department of Pharmacology, Bioengineering, Chemistry, and Biochemistry, UCSD, San Diego, California, USA
| | - Mark P. Keller
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Hui Gao
- Department of Medicine (H7), Karolinska Institutet, Karolinska University Hospital, Huddinge, Stockholm, Sweden
| | - Ruth T. Yu
- Gene Expression Laboratory, Salk Institute for Biological Sciences, La Jolla, California, USA
| | - Christopher Liddle
- Storr Liver Centre, Westmead Institute for Medical Research and Sydney School of Medicine, University of Sydney, Westmead, New South Wales, Australia
| | - Michael Downes
- Gene Expression Laboratory, Salk Institute for Biological Sciences, La Jolla, California, USA
| | - Jin Zhang
- Department of Pharmacology, Bioengineering, Chemistry, and Biochemistry, UCSD, San Diego, California, USA
| | - Aldons J. Lusis
- Department of Microbiology, Immunology, and Molecular Genetics, Department of Medicine, UCLA, Los Angeles, California, USA
| | - Alan D. Attie
- Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ronald M. Evans
- Gene Expression Laboratory, Salk Institute for Biological Sciences, La Jolla, California, USA
| | - Mikael Rydén
- Department of Medicine (H7), Karolinska Institutet, Karolinska University Hospital, Huddinge, Stockholm, Sweden
| | - Alan R. Saltiel
- Department of Medicine and
- Department of Pharmacology, Bioengineering, Chemistry, and Biochemistry, UCSD, San Diego, California, USA
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9
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Ni Z, Cheng X. Origin and Isoform Specific Functions of Exchange Proteins Directly Activated by cAMP: A Phylogenetic Analysis. Cells 2021; 10:cells10102750. [PMID: 34685730 PMCID: PMC8534922 DOI: 10.3390/cells10102750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 10/09/2021] [Accepted: 10/09/2021] [Indexed: 12/21/2022] Open
Abstract
Exchange proteins directly activated by cAMP (EPAC1 and EPAC2) are one of the several families of cellular effectors of the prototypical second messenger cAMP. To understand the origin and molecular evolution of EPAC proteins, we performed a comprehensive phylogenetic analysis of EPAC1 and EPAC2. Our study demonstrates that unlike its cousin PKA, EPAC proteins are only present in multicellular Metazoa. Within the EPAC family, EPAC1 is only associated with chordates, while EPAC2 spans the entire animal kingdom. Despite a much more contemporary origin, EPAC1 proteins show much more sequence diversity among species, suggesting that EPAC1 has undergone more selection and evolved faster than EPAC2. Phylogenetic analyses of the individual cAMP binding domain (CBD) and guanine nucleotide exchange (GEF) domain of EPACs, two most conserved regions between the two isoforms, further reveal that EPAC1 and EPAC2 are closely clustered together within both the larger cyclic nucleotide receptor and RAPGEF families. These results support the notion that EPAC1 and EPAC2 share a common ancestor resulting from a fusion between the CBD of PKA and the GEF from RAPGEF1. On the other hand, the two terminal extremities and the RAS-association (RA) domains show the most sequence diversity between the two isoforms. Sequence diversities within these regions contribute significantly to the isoform-specific functions of EPACs. Importantly, unique isoform-specific sequence motifs within the RA domain have been identified.
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Affiliation(s)
- Zhuofu Ni
- Department of Integrative Biology & Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
| | - Xiaodong Cheng
- Department of Integrative Biology & Pharmacology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA;
- Texas Therapeutics Institute, Institute of Molecular Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
- Correspondence: ; Tel.: +1-713-500-7487
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Abstract
Glucose-dependent insulinotropic polypeptide (GIP) (also known as gastric inhibitory polypeptide) is a hormone produced in the upper gut and secreted to the circulation in response to the ingestion of foods, especially fatty foods. Growing evidence supports the physiological and pharmacological relevance of GIP in obesity. In an obesity setting, inhibition of endogenous GIP or its receptor leads to decreased energy intake, increased energy expenditure, or both, eventually causing weight loss. Further, supraphysiological dosing of exogenous long-lasting GIP agonists alters energy balance and has a marked antiobesity effect. This remarkable yet paradoxical antiobesity effect is suggested to occur primarily via the brain. The brain is capable of regulating both energy intake and expenditure and plays a critical role in human obesity. In addition, the GIP receptor is widely distributed throughout the brain, including areas responsible for energy homeostasis. Recent studies have uncovered previously underappreciated roles of the GIP receptor in the brain in the context of obesity. This article highlights how the GIP receptor expressed by the brain impacts obesity-related pathogenesis.
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Affiliation(s)
- Makoto Fukuda
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX
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11
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Yadav T, Magotra A, Bangar YC, Kumar R, Yadav AS, Garg AR, Bahurupi P, Kumar P. Effect of BsaA I genotyped intronic SNP of leptin gene on production and reproduction traits in Indian dairy cattle. Anim Biotechnol 2021; 34:261-267. [PMID: 34370619 DOI: 10.1080/10495398.2021.1955701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In the present study, candidate single nucleotide polymorphism (SNP) g.92450765 G > A of leptin gene was explored for Bos indicus cattle with an aim to explore its possible effect on production and reproduction traits. The genotypic and allelic frequencies of BsaA 1 genotyped SNP g.92450765 G > A indicated the predominance of AG (0.65) genotyped Sahiwal cows in our studied population. The least-squares analysis showed a significant association (p < 0.05) of identified genetic variants with total milk yield (TMY) and 305 days milk yield (MY) (p < 0.05). The GG genotyped cows were found to be associated with higher milk yields. However, for reproduction traits under study AA genotype was found to be more favorable with respect to service period and calving interval (p < 0.05). Computational analysis was also performed to predict changes if any in the transcription factor binding sites (TFBS) caused due to the identified SNP in the intronic region of the leptin gene. TFBS analysis predicted that the targeted SNP at g.92450765G > A may lead to the disappearance of TFBS such as Hypermethylated in cancer 2 protein (HIC2), Max-binding protein MNT (MNT), Cyclic AMP-dependent transcription factor -3 (ATF3), Myc-associated factor X (MAX) and Microphthalmia-associated transcription factor (MITF). It may lead to changes in transcriptional regulation.
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Affiliation(s)
- Tejwanti Yadav
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
| | - Ankit Magotra
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
| | - Yogesh C Bangar
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
| | - Ramesh Kumar
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
| | - A S Yadav
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
| | - Asha Rani Garg
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
| | - Pooja Bahurupi
- Department of Animal Genetics and Breeding, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
| | - Pankaj Kumar
- Disease Investigation Lab Rohtak, Lala Lajpat Rai University of Veterinary and Animal Sciences (LUVAS), Hisar, India
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12
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Butiaeva LI, Slutzki T, Swick HE, Bourguignon C, Robins SC, Liu X, Storch KF, Kokoeva MV. Leptin receptor-expressing pericytes mediate access of hypothalamic feeding centers to circulating leptin. Cell Metab 2021; 33:1433-1448.e5. [PMID: 34129812 DOI: 10.1016/j.cmet.2021.05.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 02/19/2021] [Accepted: 05/21/2021] [Indexed: 12/18/2022]
Abstract
Knowledge of how leptin receptor (LepR) neurons of the mediobasal hypothalamus (MBH) access circulating leptin is still rudimentary. Employing intravital microscopy, we found that almost half of the blood-vessel-enwrapping pericytes in the MBH express LepR. Selective disruption of pericytic LepR led to increased food intake, increased fat mass, and loss of leptin-dependent signaling in nearby LepR neurons. When delivered intravenously, fluorescently tagged leptin accumulated at hypothalamic LepR pericytes, which was attenuated upon pericyte-specific LepR loss. Because a paracellular tracer was also preferentially retained at LepR pericytes, we pharmacologically targeted regulators of inter-endothelial junction tightness and found that they affect LepR neuronal signaling and food intake. Optical imaging in MBH slices revealed a long-lasting, tonic calcium increase in LepR pericytes in response to leptin, suggesting pericytic contraction and vessel constriction. Together, our data indicate that LepR pericytes facilitate localized, paracellular blood-brain barrier leaks, enabling MBH LepR neurons to access circulating leptin.
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Affiliation(s)
- Liliia I Butiaeva
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Tal Slutzki
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Hannah E Swick
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Clément Bourguignon
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal QC H4H 1R3, Canada; Integrated Program in Neuroscience, McGill University, Montreal QC H3A 2B4, Canada
| | - Sarah C Robins
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada
| | - Xiaohong Liu
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada
| | - Kai-Florian Storch
- Department of Psychiatry, Douglas Mental Health University Institute, McGill University, Montreal QC H4H 1R3, Canada
| | - Maia V Kokoeva
- Division of Endocrinology, Department of Medicine, McGill University Health Center Research Institute, McGill University, Montreal QC H4A 3J1, Canada.
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13
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Kaneko K, Lin HY, Fu Y, Saha PK, De la Puente-Gomez AB, Xu Y, Ohinata K, Chen P, Morozov A, Fukuda M. Rap1 in the VMH regulates glucose homeostasis. JCI Insight 2021; 6:142545. [PMID: 33974562 PMCID: PMC8262364 DOI: 10.1172/jci.insight.142545] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 05/05/2021] [Indexed: 12/14/2022] Open
Abstract
The hypothalamus is a critical regulator of glucose metabolism and is capable of correcting diabetes conditions independently of an effect on energy balance. The small GTPase Rap1 in the forebrain is implicated in high-fat diet–induced (HFD-induced) obesity and glucose imbalance. Here, we report that increasing Rap1 activity selectively in the medial hypothalamus elevated blood glucose without increasing the body weight of HFD-fed mice. In contrast, decreasing hypothalamic Rap1 activity protected mice from diet-induced hyperglycemia but did not prevent weight gain. The remarkable glycemic effect of Rap1 was reproduced when Rap1 was specifically deleted in steroidogenic factor-1–positive (SF-1–positive) neurons in the ventromedial hypothalamic nucleus (VMH) known to regulate glucose metabolism. While having no effect on body weight regardless of sex, diet, and age, Rap1 deficiency in the VMH SF1 neurons markedly lowered blood glucose and insulin levels, improved glucose and insulin tolerance, and protected mice against HFD-induced neural leptin resistance and peripheral insulin resistance at the cellular and whole-body levels. Last, acute pharmacological inhibition of brain exchange protein directly activated by cAMP 2, a direct activator of Rap1, corrected glucose imbalance in obese mouse models. Our findings uncover the primary role of VMH Rap1 in glycemic control and implicate Rap1 signaling as a potential target for therapeutic intervention in diabetes.
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Affiliation(s)
- Kentaro Kaneko
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto, Japan
| | - Hsiao-Yun Lin
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Yukiko Fu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Department of Molecular Medicine and Metabolism, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Japan
| | | | - Ana B De la Puente-Gomez
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Kousaku Ohinata
- Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Uji, Kyoto, Japan
| | - Peter Chen
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Women's Guild Lung Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Alexei Morozov
- Unit on Behavioral Genetics, Laboratory of Molecular Pathophysiology, National Institute of Mental Health, NIH, Maryland, USA.,Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia, USA
| | - Makoto Fukuda
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
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14
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Massimi M, Ragusa F, Cardarelli S, Giorgi M. Targeting Cyclic AMP Signalling in Hepatocellular Carcinoma. Cells 2019; 8:cells8121511. [PMID: 31775395 PMCID: PMC6952960 DOI: 10.3390/cells8121511] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 11/21/2019] [Accepted: 11/22/2019] [Indexed: 02/06/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is a major healthcare problem worldwide, representing one of the leading causes of cancer mortality. Since there are currently no predictive biomarkers for early stage diagnosis, HCC is detected only in advanced stages and most patients die within one year, as radical tumour resection is generally performed late during the disease. The development of alternative therapeutic approaches to HCC remains one of the most challenging areas of cancer. This review focuses on the relevance of cAMP signalling in the development of hepatocellular carcinoma and identifies the modulation of this second messenger as a new strategy for the control of tumour growth. In addition, because the cAMP pathway is controlled by phosphodiesterases (PDEs), targeting these enzymes using PDE inhibitors is becoming an attractive and promising tool for the control of HCC. Among them, based on current preclinical and clinical findings, PDE4-specific inhibitors remarkably demonstrate therapeutic potential in the management of cancer outcomes, especially as adjuvants to standard therapies. However, more preclinical studies are warranted to ascertain their efficacy during the different stages of hepatocyte transformation and in the treatment of established HCC.
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Affiliation(s)
- Mara Massimi
- Department of Life, Health and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy;
- Correspondence: (M.M.); (M.G.); Tel.: +39-0862-433219 (M.M.); +39-06-49912308 (M.G.)
| | - Federica Ragusa
- Department of Life, Health and Environmental Sciences, University of L’Aquila, 67100 L’Aquila, Italy;
| | - Silvia Cardarelli
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, 00185 Rome, Italy;
| | - Mauro Giorgi
- Department of Biology and Biotechnology “Charles Darwin”, Sapienza University of Rome, 00185 Rome, Italy;
- Correspondence: (M.M.); (M.G.); Tel.: +39-0862-433219 (M.M.); +39-06-49912308 (M.G.)
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15
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Zhao S, Zhu Y, Schultz RD, Li N, He Z, Zhang Z, Caron A, Zhu Q, Sun K, Xiong W, Deng H, Sun J, Deng Y, Kim M, Lee CE, Gordillo R, Liu T, Odle AK, Childs GV, Zhang N, Kusminski CM, Elmquist JK, Williams KW, An Z, Scherer PE. Partial Leptin Reduction as an Insulin Sensitization and Weight Loss Strategy. Cell Metab 2019; 30:706-719.e6. [PMID: 31495688 PMCID: PMC6774814 DOI: 10.1016/j.cmet.2019.08.005] [Citation(s) in RCA: 160] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Revised: 07/17/2019] [Accepted: 08/07/2019] [Indexed: 12/12/2022]
Abstract
The physiological role of leptin is thought to be a driving force to reduce food intake and increase energy expenditure. However, leptin therapies in the clinic have failed to effectively treat obesity, predominantly due to a phenomenon referred to as leptin resistance. The mechanisms linking obesity and the associated leptin resistance remain largely unclear. With various mouse models and a leptin neutralizing antibody, we demonstrated that hyperleptinemia is a driving force for metabolic disorders. A partial reduction of plasma leptin levels in the context of obesity restores hypothalamic leptin sensitivity and effectively reduces weight gain and enhances insulin sensitivity. These results highlight that a partial reduction in plasma leptin levels leads to improved leptin sensitivity, while pointing to a new avenue for therapeutic interventions in the treatment of obesity and its associated comorbidities.
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Affiliation(s)
- Shangang Zhao
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yi Zhu
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Robbie D Schultz
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Na Li
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Zhenyan He
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Neurosurgery and Endocrinology, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Zhuzhen Zhang
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Alexandre Caron
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Qingzhang Zhu
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kai Sun
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Center for Metabolic and Degenerative Diseases, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Wei Xiong
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Hui Deng
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Jia Sun
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Neurosurgery and Endocrinology, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China
| | - Yingfeng Deng
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Min Kim
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biological Sciences, School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, South Korea
| | - Charlotte E Lee
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ruth Gordillo
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Tiemin Liu
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Angela K Odle
- Neurobiology & Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences
| | - Gwen V Childs
- Neurobiology & Developmental Sciences, College of Medicine, University of Arkansas for Medical Sciences
| | - Ningyan Zhang
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Christine M Kusminski
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Joel K Elmquist
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kevin W Williams
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Zhiqiang An
- Texas Therapeutics Institute, Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX, USA.
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16
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Abstract
Developing effective treatments for obesity and related metabolic disease remains a challenge. One logical strategy targets the appetite-regulating actions of gut hormones such as incretins. One of these incretins, glucose-dependent insulinotropic polypeptide (GIP), has garnered much attention as a potential target: however, whether it is beneficial to boost or block the action of GIP to promote weight loss remains an unresolved question. In this issue of the JCI, Kaneko and colleagues show that antagonizing GIP signaling in the CNS enhances the weight-reducing effects of leptin in rodents with diet-induced obesity. The authors posit that an increase in circulating intestinally derived GIP, as a consequence of overnutrition, acts in the brain to impair hypothalamic leptin action, resulting in increased food intake and body weight gain. This research advances the idea that multiple GIP signaling pathways and mechanisms exist in the obese state and offers intriguing new insights into the antiobesogenic consequences of antagonizing brain GIP action.
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Affiliation(s)
- Jessica T Y Yue
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada
| | - Tony K T Lam
- Toronto General Hospital Research Institute, University Health Network (UHN), Toronto, Ontario, Canada.,Department of Physiology.,Department of Medicine, and.,Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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17
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Kaneko K, Fu Y, Lin HY, Cordonier EL, Mo Q, Gao Y, Yao T, Naylor J, Howard V, Saito K, Xu P, Chen SS, Chen MH, Xu Y, Williams KW, Ravn P, Fukuda M. Gut-derived GIP activates central Rap1 to impair neural leptin sensitivity during overnutrition. J Clin Invest 2019; 129:3786-3791. [PMID: 31403469 PMCID: PMC6715359 DOI: 10.1172/jci126107] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 06/11/2019] [Indexed: 01/16/2023] Open
Abstract
Nutrient excess, a major driver of obesity, diminishes hypothalamic responses to exogenously administered leptin, a critical hormone of energy balance. Here, we aimed to identify a physiological signal that arises from excess caloric intake and negatively controls hypothalamic leptin action. We found that deficiency of the gastric inhibitory polypeptide receptor (Gipr) for the gut-derived incretin hormone GIP protected against diet-induced neural leptin resistance. Furthermore, a centrally administered antibody that neutralizes GIPR had remarkable antiobesity effects in diet-induced obese mice, including reduced body weight and adiposity, and a decreased hypothalamic level of SOCS3, an inhibitor of leptin actions. In contrast, centrally administered GIP diminished hypothalamic sensitivity to leptin and increased hypothalamic levels of Socs3. Finally, we show that GIP increased the active form of the small GTPase Rap1 in the brain and that its activation was required for the central actions of GIP. Altogether, our results identify GIPR/Rap1 signaling in the brain as a molecular pathway linking overnutrition to the control of neural leptin actions.
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Affiliation(s)
- Kentaro Kaneko
- Children’s Nutrition Research Center, Department of Pediatrics and
| | - Yukiko Fu
- Children’s Nutrition Research Center, Department of Pediatrics and
| | - Hsiao-Yun Lin
- Children’s Nutrition Research Center, Department of Pediatrics and
| | | | - Qianxing Mo
- Dan L. Duncan Cancer Center and Center for Cell Gene and Therapy, Baylor College of Medicine, Houston, Texas, USA
| | - Yong Gao
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ting Yao
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
- Department of Physiology and Pathophysiology, Xi’an Jiaotong University School of Medicine, Xi’an, Shaanxi, China
| | - Jacqueline Naylor
- AstraZeneca, R&D BioPharmaceuticals Unit, Cardiovascular, Renal and Metabolism, Cambridge, United Kingdom
| | - Victor Howard
- AstraZeneca, R&D BioPharmaceuticals Unit, Cardiovascular, Renal and Metabolism, Gaithersburg, Maryland, USA
| | - Kenji Saito
- Children’s Nutrition Research Center, Department of Pediatrics and
| | - Pingwen Xu
- Children’s Nutrition Research Center, Department of Pediatrics and
| | - Siyu S. Chen
- Children’s Nutrition Research Center, Department of Pediatrics and
| | - Miao-Hsueh Chen
- Children’s Nutrition Research Center, Department of Pediatrics and
| | - Yong Xu
- Children’s Nutrition Research Center, Department of Pediatrics and
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Kevin W. Williams
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | - Peter Ravn
- AstraZeneca, R&D BioPharmaceuticals Unit, Department of Antibody Discovery and Protein Engineering, Cambridge, United Kingdom
| | - Makoto Fukuda
- Children’s Nutrition Research Center, Department of Pediatrics and
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18
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Reverte-Salisa L, Sanyal A, Pfeifer A. Role of cAMP and cGMP Signaling in Brown Fat. Handb Exp Pharmacol 2019; 251:161-182. [PMID: 29633180 DOI: 10.1007/164_2018_117] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Cold-induced activation of brown adipose tissue (BAT) is mediated by norepinephrine and adenosine that are released during sympathetic nerve activation. Both signaling molecules induce an increase in intracellular levels of 3',5'-cyclic adenosine monophosphate (cAMP) in murine and human BAT. In brown adipocytes, cAMP plays a central role, because it activates lipolysis, glucose uptake, and thermogenesis. Another well-studied intracellular second messenger is 3',5'-cyclic guanosine monophosphate (cGMP), which closely resembles cAMP. Several studies have shown that intact cGMP signaling is essential for normal adipogenic differentiation and BAT-mediated thermogenesis in mice. This chapter highlights recent observations, demonstrating the physiological significance of cyclic nucleotide signaling in BAT as well as their potential to induce browning of white adipose tissue (WAT) in mice and humans.
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Affiliation(s)
- Laia Reverte-Salisa
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Abhishek Sanyal
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University Hospital Bonn, University of Bonn, Bonn, Germany.
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19
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Cordonier EL, Liu T, Saito K, Chen SS, Xu Y, Fukuda M. Luciferase Reporter Mice for In Vivo Monitoring and Ex Vivo Assessment of Hypothalamic Signaling of Socs3 Expression. J Endocr Soc 2019; 3:1246-1260. [PMID: 31214662 PMCID: PMC6570635 DOI: 10.1210/js.2019-00077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/17/2019] [Indexed: 11/19/2022] Open
Abstract
Suppressor of cytokine signaling-3 (SOCS3) is a negative regulator of actions of cytokines and the metabolic hormone leptin. In the hypothalamus, SOCS3 is induced in response to several conditions such as inflammation and high-fat diet feeding, modulates cellular signaling of cytokines and leptin, and mediates the effects of these biological conditions. However, signaling mechanisms controlling hypothalamic Socs3 expression remains to be fully established. To facilitate the identification of molecular pathways of Socs3 induction, we generated a real-time gene expression reporter mouse of Socs3 (Socs3-Luc mice). We successfully detected a remarkable increase in luciferase activity in various tissues of Socs3-Luc mice in response to a peripheral injection of lipopolysaccharide, a potent inducer of inflammation, reflecting expression levels of endogenous Socs3 mRNA. Using ex vivo hypothalamic explants of Socs3-Luc mice, we demonstrate that hypothalamic luciferase activity was significantly elevated in slices stimulated with known inducers of Socs3 such as proinflammatory cytokines IL-6, IL-1β, and TNF-α, lipopolysaccharide, and cAMP-inducing agent forskolin. Using the ex vivo model, we found glycogen synthase kinase-3 (GSK3)β-specific inhibitors to be potent inducers of Socs3. Furthermore, pharmacological inhibitors of β-catenin, a downstream mediator of GSK3β signaling, reduced Socs3 luciferase activity ex vivo. Finally, hypothalamic inhibition of GSK3β hindered leptin-induced phosphorylation of signal transducers and activators of transcription 3 in hypothalamic explants. These results suggest that the Socs3-luciferase mouse is useful for in vivo monitoring of Socs3 gene expression and for ex vivo slice-based screening to identify signaling pathways that control Socs3 in the hypothalamus.
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Affiliation(s)
- Elizabeth L Cordonier
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Tiemin Liu
- Division of Hypothalamic Research, Department of Internal Medicine, The University of Texas Southwestern Medical Center at Dallas, Dallas, Texas
| | - Kenji Saito
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Siyu S Chen
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas
| | - Makoto Fukuda
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas
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20
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Tazawa R, Uchida K, Fujimaki H, Miyagi M, Inoue G, Sekiguchi H, Murata K, Takata K, Kawakubo A, Takaso M. Elevated leptin levels induce inflammation through IL-6 in skeletal muscle of aged female rats. BMC Musculoskelet Disord 2019; 20:199. [PMID: 31077169 PMCID: PMC6511122 DOI: 10.1186/s12891-019-2581-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 04/22/2019] [Indexed: 01/06/2023] Open
Abstract
Background Chronic inflammation with aging contributes to sarcopenia. Previous studies have suggested that the accumulation of adipose tissue in skeletal muscle, referred to as intermuscular adipose tissue (IMAT), increases with age and is associated with inflammation. However, the mechanism governing ectopic inflammation in skeletal muscle due to aging is not fully understood. Leptin, an adipocytokine derived from adipose tissue, is an important mediator of inflammatory processes. We examined changes in leptin levels with age and whether leptin contributes to ectopic inflammation. Methods To evaluate ectopic inflammation in skeletal muscle, we measured alterations to the expression of inflammatory cytokine genes (Il1b, Il6, and Tnfa) and muscle break down-related gene (MuRF1 and Atrogin1) in the quadricep muscles of young (10 weeks) and aged (48 weeks) female rats using quantitative reverse-transcription polymerase chain reaction (Q-RT-PCR). Histological examination was performed to identify the extent of IMAT. Leptin mRNA and leptin protein expression were examined using Q-RT-PCR and enzyme-linked immunosorbent assay, respectively. The effect of leptin on the mRNA expression of Il1b, Il6, and Tnfa in quadricep muscle-derived cells was also examined by stimulating the cells with 0 (control), 1, or 10 μg/mL rat recombinant leptin using Q-RT-PCR. Results Aged rats had significantly higher Il6, MuRF1, and Atrogin1 but not Il1b and Tnfa, expression and greater levels of IMAT in their quadricep muscles than young rats. Aged rats also had significantly higher leptin expression and leptin protein concentration in their quadricep muscles than young rats. The addition of exogenous leptin to quadricep muscle-derived cells significantly increased the gene expression of Il1b and Il6 but not Tnfa. Conclusions Our results suggest that elevated leptin levels due to aging cause ectopic inflammation through IL-6 in the skeletal muscle of aged rats. Electronic supplementary material The online version of this article (10.1186/s12891-019-2581-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ryo Tazawa
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
| | - Kentaro Uchida
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan.
| | - Hisako Fujimaki
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
| | - Masayuki Miyagi
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
| | - Gen Inoue
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
| | - Hiroyuki Sekiguchi
- Shonan University of Medical Sciences Research Institute, Nishikubo 500, Chigasaki City, Kanagawa, 253-0083, Japan
| | - Kosuke Murata
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
| | - Ken Takata
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
| | - Ayumu Kawakubo
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
| | - Masashi Takaso
- Department of Orthopedic Surgery, Kitasato University School of Medicine, 1-15-1 Minami-ku, Kitasato, Sagamihara City, Kanagawa, 252-0374, Japan
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21
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Robichaux WG, Cheng X. Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development. Physiol Rev 2018; 98:919-1053. [PMID: 29537337 PMCID: PMC6050347 DOI: 10.1152/physrev.00025.2017] [Citation(s) in RCA: 138] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 12/13/2022] Open
Abstract
This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.
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Affiliation(s)
- William G Robichaux
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, The Brown Foundation Institute of Molecular Medicine, The University of Texas Health Science Center , Houston, Texas
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22
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Li K, Liang J, Lin Y, Zhang H, Xiao X, Tan Y, Cai J, Zhu W, Xing F, Hu J, Yan G. A classical PKA inhibitor increases the oncolytic effect of M1 virus via activation of exchange protein directly activated by cAMP 1. Oncotarget 2018; 7:48443-48455. [PMID: 27374176 PMCID: PMC5217030 DOI: 10.18632/oncotarget.10305] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 06/09/2016] [Indexed: 11/25/2022] Open
Abstract
Oncolytic virotherapy is an emerging and promising treatment modality that uses replicating viruses as selective antitumor agents. Here, we report that a classical protein kinase A (PKA) inhibitor, H89, synergizes with oncolytic virus M1 in various cancer cells through activation of Epac1 (exchange protein directly activated by cAMP 1). H89 substantially increases viral replication in refractory cancer cells, leading to unresolvable Endoplasmic Reticulum stress, and cell apoptosis. Microarray analysis indicates that H89 blunts antiviral response in refractory cancer cells through retarding the nuclear translocation of NF-κB. Importantly, in vivo studies show significant antitumor effects during M1/H89 combination treatment. Overall, this study reveals a previously unappreciated role for H89 and demonstrates that activation of the Epac1 activity can improve the responsiveness of biotherapeutic agents for cancer.
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Affiliation(s)
- Kai Li
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Jiankai Liang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Yuan Lin
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Haipeng Zhang
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Xiao Xiao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China.,Department of Pharmacy, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China
| | - Yaqian Tan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Jing Cai
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Wenbo Zhu
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Fan Xing
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Jun Hu
- Department of Microbiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China
| | - Guangmei Yan
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China.,Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University, Guangzhou 510080, China
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23
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Abstract
Leptin is an adipocyte-derived hormone, which contributes to the homeostatic regulation of energy balance and metabolism through humoral and neural pathways. Leptin acts on the neurons in certain brain areas such as the hypothalamus, hippocampus, and brain stem to regulate food intake, thermogenesis, energy expenditure, and homeostasis of glucose/lipid metabolism. The pathologically increased circulating leptin is a biomarker of leptin resistance, which is common in obese individuals. Leptin resistance is defined by a reduced sensitivity or a failure in response of the brain to leptin, showing a decrease in the ability of leptin to suppress appetite or enhance energy expenditure, which causes an increased food intake and finally leads to overweight, obesity, cardiovascular diseases, and other metabolic disorders. Leptin resistance is a challenge for clinical treatment or drug discovery of obesity. Until recently, emerging evidence has been showing novel mechanisms of the leptin resistance. Here, we summarized the advances and controversy of leptin resistance and associated diseases, for better understanding the physiology and pathophysiology of leptin as well as the new strategies for treating obesity and metabolic disorders.
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24
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Mechanick JI, Zhao S, Garvey WT. Leptin, An Adipokine With Central Importance in the Global Obesity Problem. Glob Heart 2017; 13:113-127. [PMID: 29248361 DOI: 10.1016/j.gheart.2017.10.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 10/25/2017] [Indexed: 02/08/2023] Open
Abstract
Leptin has central importance in the global obesity and cardiovascular disease problem. Leptin is principally secreted by adipocytes and acts in the hypothalamus to suppress appetite and food intake, increase energy expenditure, and regulate body weight. Based on clinical translation of specific and networked actions, leptin affects the cardiovascular system and may be a marker and driver of cardiometabolic risk factors with interventions that are actionable by cardiologists. Leptin subnetwork analysis demonstrates a statistically significant role for ethnoculturally and socioeconomically appropriate lifestyle intervention in cardiovascular disease. Emergent mechanistic components and potential diagnostic or therapeutic targets include hexokinase 3, urocortins, clusterin, sialic acid-binding immunoglobulin-like lectin 6, C-reactive protein, platelet glycoprotein VI, albumin, pentraxin 3, ghrelin, obestatin prepropeptide, leptin receptor, neuropeptide Y, and corticotropin-releasing factor receptor 1. Emergent associated symptoms include weight change, eating disorders, vascular necrosis, chronic fatigue, and chest pain. Leptin-targeted therapies are reported for lipodystrophy and leptin deficiency, but they are investigational for leptin resistance, obesity, and other chronic diseases.
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Affiliation(s)
- Jeffrey I Mechanick
- Division of Cardiology, Icahn School of Medicine at Mount Sinai, New York, NY, USA; Division of Endocrinology, Diabetes, and Bone Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
| | - Shan Zhao
- Basepaws Inc., Redondo Beach, CA, USA
| | - W Timothy Garvey
- Department of Nutritional Sciences and Diabetes Research Center, University of Alabama at Birmingham, Birmingham, AL, USA; Geriatric Research Education and Clinical Center, Birmingham Veterans Affairs Medical Center, Birmingham, AL, USA
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25
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Kaneko K, Xu P, Cordonier EL, Chen SS, Ng A, Xu Y, Morozov A, Fukuda M. Neuronal Rap1 Regulates Energy Balance, Glucose Homeostasis, and Leptin Actions. Cell Rep 2017; 16:3003-3015. [PMID: 27626668 DOI: 10.1016/j.celrep.2016.08.039] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 06/30/2016] [Accepted: 08/11/2016] [Indexed: 10/21/2022] Open
Abstract
The CNS contributes to obesity and metabolic disease; however, the underlying neurobiological pathways remain to be fully established. Here, we show that the small GTPase Rap1 is expressed in multiple hypothalamic nuclei that control whole-body metabolism and is activated in high-fat diet (HFD)-induced obesity. Genetic ablation of CNS Rap1 protects mice from dietary obesity, glucose imbalance, and insulin resistance in the periphery and from HFD-induced neuropathological changes in the hypothalamus, including diminished cellular leptin sensitivity and increased endoplasmic reticulum (ER) stress and inflammation. Furthermore, pharmacological inhibition of CNS Rap1 signaling normalizes hypothalamic ER stress and inflammation, improves cellular leptin sensitivity, and reduces body weight in mice with dietary obesity. We also demonstrate that Rap1 mediates leptin resistance via interplay with ER stress. Thus, neuronal Rap1 critically regulates leptin sensitivity and mediates HFD-induced obesity and hypothalamic pathology and may represent a potential therapeutic target for obesity treatment.
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Affiliation(s)
- Kentaro Kaneko
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Pingwen Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Elizabeth L Cordonier
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Siyu S Chen
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Amy Ng
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, TX 77030, USA
| | - Alexei Morozov
- Unit on Behavioral Genetics, Laboratory of Molecular Pathophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA; Virginia Tech Carilion Research Institute, Roanoke, VA 24016, USA
| | - Makoto Fukuda
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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26
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Yu YH. Making sense of metabolic obesity and hedonic obesity. J Diabetes 2017; 9:656-666. [PMID: 28093902 DOI: 10.1111/1753-0407.12529] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/10/2017] [Accepted: 01/10/2017] [Indexed: 01/01/2023] Open
Abstract
Body weight is neither stationary nor does it change unidirectionally. Rather, body weight usually oscillates up and down around a set point. Two types of forces determine the direction of weight changes. Forces that push body weight away from the set point are defined as non-homeostatic and are governed by multiple mechanisms, including, but not limited to, hedonic regulation of food intake. Forces that restore the set point weight are defined as homeostatic, and they operate through mechanisms that regulate short-term energy balance driven by hunger and satiation and long-term energy balance driven by changes in adiposity. In the normal physiological state, the deviation of body weight from the set point is usually small and temporary, and is constantly corrected by homeostatic forces. Metabolic obesity develops when body weight set point is shifted to an abnormally high level and the obese body weight becomes metabolically defended. In hedonic obesity, the obese body weight is maintained by consistent overeating due to impairments in the reward system, although the set point is not elevated. Adaptive increases in energy expenditure are elicited in hedonic obesity because body weight is elevated above the set point. Neither subtype of obesity undergoes spontaneous resolution unless the underlying disorders are corrected. In this review, the need for both appropriate patient stratification and tailored treatments is discussed in the context of the new framework of metabolic and hedonic obesity.
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Affiliation(s)
- Yi-Hao Yu
- Department of Endocrinology, Greenwich Hospital and Northeast Medical Group, Yale-New Haven Health System, Greenwich, Connecticut, USA
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27
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Abstract
Obesity, a major risk factor for the development of diabetes mellitus, cardiovascular diseases and certain types of cancer, arises from a chronic positive energy balance that is often due to unlimited access to food and an increasingly sedentary lifestyle on the background of a genetic and epigenetic vulnerability. Our understanding of the humoral and neuronal systems that mediate the control of energy homeostasis has improved dramatically in the past few decades. However, our ability to develop effective strategies to slow the current epidemic of obesity has been hampered, largely owing to the limited knowledge of the mechanisms underlying resistance to the action of metabolic hormones such as leptin and ghrelin. The development of resistance to leptin and ghrelin, hormones that are crucial for the neuroendocrine control of energy homeostasis, is a hallmark of obesity. Intensive research over the past several years has yielded tremendous progress in our understanding of the cellular pathways that disrupt the action of leptin and ghrelin. In this Review, we discuss the molecular mechanisms underpinning resistance to leptin and ghrelin and how they can be exploited as targets for pharmacological management of obesity.
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Affiliation(s)
- Huxing Cui
- Department of Pharmacology, University of Iowa, Iowa City, Iowa 52246, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa 52242, USA
| | - Miguel López
- Department of Physiology, Center for Research in Molecular Medicine and Chronic Diseases (CiMUS), University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain
- Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela 15706, Spain
| | - Kamal Rahmouni
- Department of Pharmacology, University of Iowa, Iowa City, Iowa 52246, USA
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, Iowa 52242, USA
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28
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Wang P, Liu Z, Chen H, Ye N, Cheng X, Zhou J. Exchange proteins directly activated by cAMP (EPACs): Emerging therapeutic targets. Bioorg Med Chem Lett 2017; 27:1633-1639. [PMID: 28283242 PMCID: PMC5397994 DOI: 10.1016/j.bmcl.2017.02.065] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 02/07/2017] [Accepted: 02/26/2017] [Indexed: 11/22/2022]
Abstract
Exchange proteins directly activated by cAMP (EPACs) are critical cAMP-dependent signaling pathway mediators. The discovery of EPAC proteins has significantly facilitated understanding on cAMP-dependent signaling pathway and efforts along this line open new avenues for developing novel therapeutics for cancer, diabetes, heart failure, inflammation, infections, neurological disorders and other human diseases. Over the past decade, important progress has been made in the identification of EPAC agonists, antagonists and their biological and pharmacological applications. In this review, we briefly summarize recently reported novel functions of EPACs and the discovery of their small molecule modulators. The challenges and future perspectives are also discussed.
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Affiliation(s)
- Pingyuan Wang
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Zhiqing Liu
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Haiying Chen
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Na Ye
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States
| | - Xiaodong Cheng
- Department of Integrative Biology and Pharmacology, Texas Therapeutics Institute, University of Texas Health Science Center, Houston, TX 77030, United States
| | - Jia Zhou
- Chemical Biology Program, Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX 77555, United States.
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29
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Parnell E, McElroy SP, Wiejak J, Baillie GL, Porter A, Adams DR, Rehmann H, Smith BO, Yarwood SJ. Identification of a Novel, Small Molecule Partial Agonist for the Cyclic AMP Sensor, EPAC1. Sci Rep 2017; 7:294. [PMID: 28331191 PMCID: PMC5428521 DOI: 10.1038/s41598-017-00455-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 02/27/2017] [Indexed: 11/26/2022] Open
Abstract
Screening of a carefully selected library of 5,195 small molecules identified 34 hit compounds that interact with the regulatory cyclic nucleotide-binding domain (CNB) of the cAMP sensor, EPAC1. Two of these hits (I942 and I178) were selected for their robust and reproducible inhibitory effects within the primary screening assay. Follow-up characterisation by ligand observed nuclear magnetic resonance (NMR) revealed direct interaction of I942 and I178 with EPAC1 and EPAC2-CNBs in vitro. Moreover, in vitro guanine nucleotide exchange factor (GEF) assays revealed that I942 and, to a lesser extent, I178 had partial agonist properties towards EPAC1, leading to activation of EPAC1, in the absence of cAMP, and inhibition of GEF activity in the presence of cAMP. In contrast, there was very little agonist action of I942 towards EPAC2 or protein kinase A (PKA). To our knowledge, this is the first observation of non-cyclic-nucleotide small molecules with agonist properties towards EPAC1. Furthermore, the isoform selective agonist nature of these compounds highlights the potential for the development of small molecule tools that selectively up-regulate EPAC1 activity.
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Affiliation(s)
- Euan Parnell
- Institute of Molecular, Cellular and Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Stuart P McElroy
- European Screening Centre, University of Dundee, Biocity Scotland, Newhouse, ML1 5UH, UK
| | - Jolanta Wiejak
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh Campus, Edinburgh, EH14 4AS, UK
| | - Gemma L Baillie
- European Screening Centre, University of Dundee, Biocity Scotland, Newhouse, ML1 5UH, UK
| | - Alison Porter
- European Screening Centre, University of Dundee, Biocity Scotland, Newhouse, ML1 5UH, UK
| | - David R Adams
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh Campus, Edinburgh, EH14 4AS, UK
| | - Holger Rehmann
- Department of Molecular Cancer Research, Centre of Biomedical Genetics and Cancer Genomics Centre, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Brian O Smith
- Institute of Molecular, Cellular and Systems Biology, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Stephen J Yarwood
- Institute of Biological Chemistry, Biophysics and Bioengineering, Heriot-Watt University, Edinburgh Campus, Edinburgh, EH14 4AS, UK.
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30
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Hwang M, Go Y, Park JH, Shin SK, Song SE, Oh BC, Im SS, Hwang I, Jeon YH, Lee IK, Seino S, Song DK. Epac2a-null mice exhibit obesity-prone nature more susceptible to leptin resistance. Int J Obes (Lond) 2016; 41:279-288. [PMID: 27867203 PMCID: PMC5309344 DOI: 10.1038/ijo.2016.208] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 10/07/2016] [Accepted: 10/30/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND The exchange protein directly activated by cAMP (Epac), which is primarily involved in cAMP signaling, has been known to be essential for controlling body energy metabolism. Epac has two isoforms: Epac1 and Epac2. The function of Epac1 on obesity was unveiled using Epac1 knockout (KO) mice. However, the role of Epac2 in obesity remains unclear. METHODS To evaluate the role of Epac2 in obesity, we used Epac2a KO mice, which is dominantly expressed in neurons and endocrine tissues. Physiological factors related to obesity were analyzed: body weight, fat mass, food intake, plasma leptin and adiponectin levels, energy expenditure, glucose tolerance, and insulin and leptin resistance. To determine the mechanism of Epac2a, mice received exogenous leptin and then hypothalamic leptin signaling was analyzed. RESULTS Epac2a KO mice appeared to have normal glucose tolerance and insulin sensitivity until 12 weeks of age, but an early onset increase of plasma leptin levels and decrease of plasma adiponectin levels compared with wild-type mice. Acute leptin injection revealed impaired hypothalamic leptin signaling in KO mice. Consistently, KO mice fed a high-fat diet (HFD) were significantly obese, presenting greater food intake and lower energy expenditure. HFD-fed KO mice were also characterized by greater impairment of hypothalamic leptin signaling and by weaker leptin-induced decrease in food consumption compared with HFD-fed wild-type mice. In wild-type mice, acute exogenous leptin injection or chronic HFD feeding tended to induce hypothalamic Epac2a expression. CONCLUSIONS Considering that HFD is an inducer of hypothalamic leptin resistance and that Epac2a functions in pancreatic beta cells during demands of greater work load, hypothalamic Epac2a may have a role in facilitating leptin signaling, at least in response to higher metabolic demands. Thus, our data indicate that Epac2a is critical for preventing obesity and thus Epac2a activators may be used to manage obesity and obesity-mediated metabolic disorders.
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Affiliation(s)
- M Hwang
- Department of Physiology and Obesity-mediated Disease Research Center, Keimyung University School of Medicine, Daegu, Korea
| | - Y Go
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - J-H Park
- Department of Physiology and Obesity-mediated Disease Research Center, Keimyung University School of Medicine, Daegu, Korea
| | - S-K Shin
- Department of Physiology and Obesity-mediated Disease Research Center, Keimyung University School of Medicine, Daegu, Korea
| | - S E Song
- Department of Physiology and Obesity-mediated Disease Research Center, Keimyung University School of Medicine, Daegu, Korea
| | - B-C Oh
- Laboratory of Molecular and Cellular Biochemistry, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon, Korea
| | - S-S Im
- Department of Physiology and Obesity-mediated Disease Research Center, Keimyung University School of Medicine, Daegu, Korea
| | - I Hwang
- Department of Physiology and Obesity-mediated Disease Research Center, Keimyung University School of Medicine, Daegu, Korea
| | - Y H Jeon
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - I-K Lee
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Korea
| | - S Seino
- Division of Molecular and Metabolic Medicine, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe, Japan
| | - D-K Song
- Department of Physiology and Obesity-mediated Disease Research Center, Keimyung University School of Medicine, Daegu, Korea
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31
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Role of Exchange Protein Directly Activated by Cyclic AMP Isoform 1 in Energy Homeostasis: Regulation of Leptin Expression and Secretion in White Adipose Tissue. Mol Cell Biol 2016; 36:2440-50. [PMID: 27381457 DOI: 10.1128/mcb.01034-15] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 06/17/2016] [Indexed: 12/18/2022] Open
Abstract
Epacs (exchange proteins directly activated by cyclic AMP [cAMP]) act as downstream effectors of cAMP and play important roles in energy balance and glucose homeostasis. While global deletion of Epac1 in mice leads to heightened leptin sensitivity in the hypothalamus and partial protection against high-fat diet (HFD)-induced obesity, the physiological functions of Epac1 in white adipose tissue (WAT) has not been explored. Here, we report that adipose tissue-specific Epac1 knockout (AEKO) mice are more prone to HFD-induced obesity, with increased food intake, reduced energy expenditure, and impaired glucose tolerance. Despite the fact that AEKO mice on HFD display increased body weight, these mice have decreased circulating leptin levels compared to their wild-type littermates. In vivo and in vitro analyses further reveal that suppression of Epac1 in WAT decreases leptin mRNA expression and secretion by inhibiting cAMP response element binding (CREB) protein and AKT phosphorylation, respectively. Taken together, our results demonstrate that Epac1 plays an important role in regulating energy balance and glucose homeostasis by promoting leptin expression and secretion in WAT.
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32
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Exchange factors directly activated by cAMP mediate melanocortin 4 receptor-induced gene expression. Sci Rep 2016; 6:32776. [PMID: 27612207 PMCID: PMC5017209 DOI: 10.1038/srep32776] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 08/15/2016] [Indexed: 01/16/2023] Open
Abstract
Gs protein-coupled receptors regulate many vital body functions by activation of cAMP response elements (CRE) via cAMP-dependent kinase A (PKA)-mediated phosphorylation of the CRE binding protein (CREB). Melanocortin 4 receptors (MC4R) are prototypical Gs-coupled receptors that orchestrate the hypothalamic control of food-intake and metabolism. Remarkably, the significance of PKA for MC4R-induced CRE-dependent transcription in hypothalamic cells has not been rigorously interrogated yet. In two hypothalamic cell lines, we observed that blocking PKA activity had only weak or no effects on reporter gene expression. In contrast, inhibitors of exchange factors directly activated by cAMP-1/2 (EPAC-1/2) mitigated MC4R-induced CRE reporter activation and mRNA induction of the CREB-dependent genes c-fos and thyrotropin-releasing hormone. Furthermore, we provide first evidence that extracellular-regulated kinases-1/2 (ERK-1/2) activated by EPACs and not PKA are the elusive CREB kinases responsible for MC4R-induced CREB/CRE activation in hypothalamic cells. Overall, these data emphasize the pivotal role of EPACs rather than PKA in hypothalamic gene expression elicited by a prototypical Gs-coupled receptor.
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33
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Kwon O, Kim KW, Kim MS. Leptin signalling pathways in hypothalamic neurons. Cell Mol Life Sci 2016; 73:1457-77. [PMID: 26786898 PMCID: PMC11108307 DOI: 10.1007/s00018-016-2133-1] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/20/2015] [Accepted: 01/07/2016] [Indexed: 12/25/2022]
Abstract
Leptin is the most critical hormone in the homeostatic regulation of energy balance among those so far discovered. Leptin primarily acts on the neurons of the mediobasal part of hypothalamus to regulate food intake, thermogenesis, and the blood glucose level. In the hypothalamic neurons, leptin binding to the long form leptin receptors on the plasma membrane initiates multiple signaling cascades. The signaling pathways known to mediate the actions of leptin include JAK-STAT signaling, PI3K-Akt-FoxO1 signaling, SHP2-ERK signaling, AMPK signaling, and mTOR-S6K signaling. Recent evidence suggests that leptin signaling in hypothalamic neurons is also linked to primary cilia function. On the other hand, signaling molecules/pathways mitigating leptin actions in hypothalamic neurons have been extensively investigated in an effort to treat leptin resistance observed in obesity. These include SOCS3, tyrosine phosphatase PTP1B, and inflammatory signaling pathways such as IKK-NFκB and JNK signaling, and ER stress-mitochondrial signaling. In this review, we discuss leptin signaling pathways in the hypothalamus, with a particular focus on the most recently discovered pathways.
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Affiliation(s)
- Obin Kwon
- Division of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, 05505, Korea
| | - Ki Woo Kim
- Department of Pharmacology, Yonsei University Wonju College of Medicine, Wonju, 26426, Korea
- Department of Global Medical Science, Yonsei University Wonju College of Medicine, Wonju, 26426, Korea
| | - Min-Seon Kim
- Division of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, Korea.
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, 05505, Korea.
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34
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Berger A, Kablan A, Yao C, Ho T, Podyma B, Weinstein LS, Chen M. Gsα Deficiency in the Ventromedial Hypothalamus Enhances Leptin Sensitivity and Improves Glucose Homeostasis in Mice on a High-Fat Diet. Endocrinology 2016; 157:600-10. [PMID: 26671183 PMCID: PMC4733121 DOI: 10.1210/en.2015-1700] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In both mice and patients with Albright hereditary osteodystrophy, heterozygous inactivating mutations of Gsα, a ubiquitously expressed G protein that mediates receptor-stimulated intracellular cAMP production, lead to obesity and insulin resistance but only when the mutation is present on the maternal allele. This parent-of-origin effect in mice was shown to be due to Gsα imprinting in one or more brain regions. The ventromedial hypothalamus (VMH) is involved in the regulation of energy and glucose homeostasis, but the role of Gsα in VMH on metabolic regulation is unknown. To examine this, we created VMH-specific Gsα-deficient mice by mating Gsα-floxed mice with SF1-cre mice. Heterozygotes with Gsα mutation on either the maternal or paternal allele had a normal metabolic phenotype, and there was no molecular evidence of Gsα imprinting, indicating that the parent-of-origin metabolic effects associated with Gsα mutations is not due to Gsα deficiency in VMH SF1 neurons. Homozygous VMH Gsα knockout mice (VMHGsKO) showed no changes in body weight on either a regular or high-fat diet. However, glucose metabolism (fasting glucose, glucose tolerance, insulin sensitivity) was significantly improved in male VMHGsKO mice, with the difference more dramatic on the high-fat diet. In addition, male VMHGsKO mice on the high-fat diet showed a greater anorexigenic effect and increased VMH signal transducer and activator of transcription-3 phosphorylation in response to leptin. These results indicate that VMH Gsα/cyclic AMP signaling regulates glucose homeostasis and alters leptin sensitivity in mice, particularly in the setting of excess caloric intake.
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Affiliation(s)
- Alta Berger
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Ahmed Kablan
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Catherine Yao
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Thuy Ho
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Brandon Podyma
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Lee S Weinstein
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | - Min Chen
- Metabolic Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
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Lee J, Yang DJ, Lee S, Hammer GD, Kim KW, Elmquist JK. Nutritional conditions regulate transcriptional activity of SF-1 by controlling sumoylation and ubiquitination. Sci Rep 2016; 6:19143. [PMID: 26750456 PMCID: PMC4707483 DOI: 10.1038/srep19143] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 11/20/2015] [Indexed: 12/23/2022] Open
Abstract
Steroidogenic factor 1 (SF-1) is a transcription factor expressed in the ventral medial nucleus of the hypothalamus that regulates energy homeostasis. However, the molecular mechanisms of SF-1 in the control of energy balance are largely unknown. Here, we show that nutritional conditions, such as the presence or absence of serum, affect SF-1 action. Serum starvation significantly decreased hypothalamic SF-1 levels by promoting ubiquitin-dependent degradation, and sumoylation was required for this process. SF-1 transcriptional activity was also differentially regulated by nutritional status. Under normal conditions, the transcriptional activity of hypothalamic SF-1 was activated by SUMO, but this was attenuated during starvation. Taken together, these results indicate that sumoylation and ubiquitination play crucial roles in the regulation of SF-1 function and that these effects are dependent on nutritional conditions, further supporting the importance of SF-1 in the control of energy homeostasis.
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Affiliation(s)
- Jiwon Lee
- Departments of Pharmacology and Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Dong Joo Yang
- Departments of Pharmacology and Global Medical Science, Institute of Lifestyle Medicine and Nuclear Receptor Research Consortium, Wonju College of Medicine, Yonsei University, Wonju, 26426, South Korea
| | - Syann Lee
- Departments of Pharmacology and Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Gary D Hammer
- Endocrine Oncology Program, Center for Organogenesis, University of Michigan Health System, Ann Arbor, Michigan 48109, USA
| | - Ki Woo Kim
- Departments of Pharmacology and Global Medical Science, Institute of Lifestyle Medicine and Nuclear Receptor Research Consortium, Wonju College of Medicine, Yonsei University, Wonju, 26426, South Korea
| | - Joel K Elmquist
- Departments of Pharmacology and Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Lewis AE, Aesoy R, Bakke M. Role of EPAC in cAMP-Mediated Actions in Adrenocortical Cells. Front Endocrinol (Lausanne) 2016; 7:63. [PMID: 27379015 PMCID: PMC4904129 DOI: 10.3389/fendo.2016.00063] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022] Open
Abstract
Adrenocorticotropic hormone regulates adrenal steroidogenesis mainly via the intracellular signaling molecule cAMP. The effects of cAMP are principally relayed by activating protein kinase A (PKA) and the more recently discovered exchange proteins directly activated by cAMP 1 and 2 (EPAC1 and EPAC2). While the intracellular roles of PKA have been extensively studied in steroidogenic tissues, those of EPACs are only emerging. EPAC1 and EPAC2 are encoded by the genes RAPGEF3 and RAPGEF4, respectively. Whereas EPAC1 is ubiquitously expressed, the expression of EPAC2 is more restricted, and typically found in endocrine tissues. Alternative promoter usage of RAPGEF4 gives rise to three different isoforms of EPAC2 that vary in their N-termini (EPAC2A, EPAC2B, and EPAC2C) and that exhibit distinct expression patterns. EPAC2A is expressed in the brain and pancreas, EPAC2B in steroidogenic cells of the adrenal gland and testis, and EPAC2C has until now only been found in the liver. In this review, we discuss current knowledge on EPAC expression and function with focus on the known roles of EPAC in adrenal gland physiology.
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Affiliation(s)
- Aurélia E. Lewis
- Department of Molecular Biology, University of Bergen, Bergen, Norway
- *Correspondence: Aurélia E. Lewis,
| | - Reidun Aesoy
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Marit Bakke
- Department of Biomedicine, University of Bergen, Bergen, Norway
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Smith PM, Brzezinska P, Hubert F, Mimee A, Maurice DH, Ferguson AV. Leptin influences the excitability of area postrema neurons. Am J Physiol Regul Integr Comp Physiol 2015; 310:R440-8. [PMID: 26719304 DOI: 10.1152/ajpregu.00326.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 12/23/2015] [Indexed: 11/22/2022]
Abstract
The area postrema (AP) is a circumventricular organ with important roles in central autonomic regulation. This medullary structure has been shown to express the leptin receptor and has been suggested to have a role in modulating peripheral signals, indicating energy status. Using RT-PCR, we have confirmed the presence of mRNA for the leptin receptor, ObRb, in AP, and whole cell current-clamp recordings from dissociated AP neurons demonstrated that leptin influenced the excitability of 51% (42/82) of AP neurons. The majority of responsive neurons (62%) exhibited a depolarization (5.3 ± 0.7 mV), while the remaining affected cells (16/42) demonstrated hyperpolarizing effects (-5.96 ± 0.95 mV). Amylin was found to influence the same population of AP neurons. To elucidate the mechanism(s) of leptin and amylin actions in the AP, we used fluorescence resonance energy transfer (FRET) to determine the effect of these peptides on cAMP levels in single AP neurons. Leptin and amylin were found to elevate cAMP levels in the same dissociated AP neurons (leptin: % total FRET response 25.3 ± 4.9, n = 14; amylin: % total FRET response 21.7 ± 3.1, n = 13). When leptin and amylin were coapplied, % total FRET response rose to 53.0 ± 8.3 (n = 6). The demonstration that leptin and amylin influence a subpopulation of AP neurons and that these two signaling molecules have additive effects on single AP neurons to increase cAMP, supports a role for the AP as a central nervous system location at which these circulating signals may act through common intracellular signaling pathways to influence central control of energy balance.
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Affiliation(s)
- Pauline M Smith
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Paulina Brzezinska
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Fabien Hubert
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Andrea Mimee
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Donald H Maurice
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Alastair V Ferguson
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Zhu L, Xu P, Cao X, Yang Y, Hinton AO, Xia Y, Saito K, Yan X, Zou F, Ding H, Wang C, Yan C, Saha P, Khan SA, Zhao J, Fukuda M, Tong Q, Clegg DJ, Chan L, Xu Y. The ERα-PI3K Cascade in Proopiomelanocortin Progenitor Neurons Regulates Feeding and Glucose Balance in Female Mice. Endocrinology 2015; 156:4474-91. [PMID: 26375425 PMCID: PMC4655219 DOI: 10.1210/en.2015-1660] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Estrogens act upon estrogen receptor (ER)α to inhibit feeding and improve glucose homeostasis in female animals. However, the intracellular signals that mediate these estrogenic actions remain unknown. Here, we report that anorexigenic effects of estrogens are blunted in female mice that lack ERα specifically in proopiomelanocortin (POMC) progenitor neurons. These mutant mice also develop insulin resistance and are insensitive to the glucose-regulatory effects of estrogens. Moreover, we showed that propyl pyrazole triol (an ERα agonist) stimulates the phosphatidyl inositol 3-kinase (PI3K) pathway specifically in POMC progenitor neurons, and that blockade of PI3K attenuates propyl pyrazole triol-induced activation of POMC neurons. Finally, we show that effects of estrogens to inhibit food intake and to improve insulin sensitivity are significantly attenuated in female mice with PI3K genetically inhibited in POMC progenitor neurons. Together, our results indicate that an ERα-PI3K cascade in POMC progenitor neurons mediates estrogenic actions to suppress food intake and improve insulin sensitivity.
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Andersen MK, Sandholt CH. Recent Progress in the Understanding of Obesity: Contributions of Genome-Wide Association Studies. Curr Obes Rep 2015; 4:401-10. [PMID: 26374640 DOI: 10.1007/s13679-015-0173-8] [Citation(s) in RCA: 15] [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] [Indexed: 12/14/2022]
Abstract
Since 2007, discovery of genetic variants associated with general obesity and fat distribution has advanced tremendously through genome-wide association studies (GWAS). Currently, the number of robustly associated loci is 190. Even though these loci explain <3 % of the variance, they have provided us a still emerging picture of genomic localization, frequency and effect size spectra, and hints of functional implications. The translation into biological knowledge has turned out to be an immense task. However, in silico enrichment analyses of genes involved in specific pathways or expressed in specific tissues have the power to suggest biological mechanisms underlying obesity. Inspired by this, we highlight genes in five loci potentially mechanistically linked to leptin-receptor trafficking and signaling in primary cilia. The clinical application of genetic knowledge as prediction, prevention, or treatment strategies is unfortunately still far from reality. Thus, despite major advances, further research is warranted to solve one of the greatest health problems in modern society.
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Affiliation(s)
- Mette Korre Andersen
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 1, 2.sal, 2100, Copenhagen, Denmark.
| | - Camilla Helene Sandholt
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 1, 2.sal, 2100, Copenhagen, Denmark.
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40
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Yang L, McKnight GS. Hypothalamic PKA regulates leptin sensitivity and adiposity. Nat Commun 2015; 6:8237. [PMID: 26381935 PMCID: PMC4576457 DOI: 10.1038/ncomms9237] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 07/30/2015] [Indexed: 12/17/2022] Open
Abstract
Mice lacking the RIIβ regulatory subunit of cyclic AMP-dependent protein kinase A (PKA) display reduced adiposity and resistance to diet-induced obesity. Here we show that RIIβ knockout (KO) mice have enhanced sensitivity to leptin's effects on both feeding and energy metabolism. After administration of a low dose of leptin, the duration of hypothalamic JAK/STAT3 signalling is increased, resulting in enhanced POMC mRNA induction. Consistent with the extended JAK/STAT3 activation, we find that the negative feedback regulator of leptin receptor signalling, Socs3, is inhibited in the hypothalamus of RIIβ KO mice. During fasting, RIIβ–PKA is activated and this correlates with an increase in CREB phosphorylation. The increase in CREB phosphorylation is absent in the fasted RIIβ KO hypothalamus. Selective inhibition of PKA activity in AgRP neurons partially recapitulates the leanness and resistance to diet-induced obesity of RIIβ KO mice. Our findings suggest that RIIβ–PKA modulates the duration of leptin receptor signalling and therefore the magnitude of the catabolic response to leptin. Mice lacking RIIβ, a regulatory subunit of protein kinase A, are lean and resistant to diet-induced obesity. Here, the authors show that RIIβ regulates leptin sensitivity, acting as a physiological brake on leptin responsiveness and the duration of leptin signalling in the hypothalamus.
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Affiliation(s)
- Linghai Yang
- Department of Pharmacology, University of Washington School of Medicine, 1959 North East Pacific Street, Box 357280, Seattle, Washington 98195, USA
| | - G Stanley McKnight
- Department of Pharmacology, University of Washington School of Medicine, 1959 North East Pacific Street, Box 357280, Seattle, Washington 98195, USA
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41
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Kettner NM, Mayo SA, Hua J, Lee C, Moore DD, Fu L. Circadian Dysfunction Induces Leptin Resistance in Mice. Cell Metab 2015; 22:448-59. [PMID: 26166747 PMCID: PMC4558341 DOI: 10.1016/j.cmet.2015.06.005] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 04/04/2015] [Accepted: 06/09/2015] [Indexed: 02/06/2023]
Abstract
Circadian disruption is associated with obesity, implicating the central clock in body weight control. Our comprehensive screen of wild-type and three circadian mutant mouse models, with or without chronic jet lag, shows that distinct genetic and physiologic interventions differentially disrupt overall energy homeostasis and Leptin signaling. We found that BMAL1/CLOCK generates circadian rhythm of C/EBPα-mediated leptin transcription in adipose. Per and Cry mutant mice show similar disruption of peripheral clock and deregulation of leptin in fat, but opposite body weight and composition phenotypes that correlate with their distinct patterns of POMC neuron deregulation in the arcuate nucleus. Chronic jet lag is sufficient to disrupt the endogenous adipose clock and also induce central Leptin resistance in wild-type mice. Thus, coupling of the central and peripheral clocks controls Leptin endocrine feedback homeostasis. We propose that Leptin resistance, a hallmark of obesity in humans, plays a key role in circadian dysfunction-induced obesity and metabolic syndromes.
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Affiliation(s)
- Nicole M Kettner
- Department of Pediatrics/U.S. Department of Agriculture/Agricultural Research Service/Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sara A Mayo
- Department of Pediatrics/U.S. Department of Agriculture/Agricultural Research Service/Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jack Hua
- Department of Pediatrics/U.S. Department of Agriculture/Agricultural Research Service/Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Choogon Lee
- Program in Neuroscience, Florida State University, College of Medicine, Tallahassee, FL 32306, USA
| | - David D Moore
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Loning Fu
- Department of Pediatrics/U.S. Department of Agriculture/Agricultural Research Service/Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
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Sahu M, Anamthathmakula P, Sahu A. Phosphodiesterase-3B-cAMP pathway of leptin signalling in the hypothalamus is impaired during the development of diet-induced obesity in FVB/N mice. J Neuroendocrinol 2015; 27:293-302. [PMID: 25702569 DOI: 10.1111/jne.12266] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Revised: 01/16/2015] [Accepted: 02/12/2015] [Indexed: 01/05/2023]
Abstract
The phosphodiesterase-3B (PDE3B)-cAMP pathway plays an important role in transducing the action of leptin in the hypothalamus. Obesity is usually associated with hyperleptinaemia and resistance to anorectic and body weight-reducing effects of leptin. To determine whether the hypothalamic PDE3B-cAMP pathway of leptin signalling is impaired during the development of diet-induced obesity (DIO), we fed male FVB/N mice a high-fat diet (HFD: 58% kcal as fat) or low-fat diet (LFD: 6% kcal as fat) for 4 weeks. HFD fed mice developed DIO in association with hyperphagia, hyperleptinaemia and hyperinsulinaemia. Leptin (i.p.) significantly increased hypothalamic PDE3B activity and phosphorylated (p)-Akt levels in LFD-fed but not in HFD-fed mice. However, basal p-Akt levels in hypothalamus were increased in DIO mice. Additionally, amongst six-microdissected brain nuclei examined, leptin selectively decreased cAMP levels in the arcuate nucleus (ARC) of LFD-fed mice but failed to do so in HFD-fed mice. We next tested whether both the PBE3B and Akt pathways of leptin signalling remained impaired in DIO mice on the HFD for 12 weeks (long-term). DIO mice were hyperinsulinaemic and hyperleptinaemic in association with impaired glucose and insulin tolerance. Although, in LFD-fed mice, leptin significantly increased PDE3B activity and p-Akt levels in the hypothalamus, it failed to do so in HFD-fed mice. Also, basal p-Akt levels in the hypothalamus were increased in DIO mice and leptin had no further effect. Similarly, immunocytochemistry showed that leptin increased the number of p-Akt-positive cells in the ARC of LFD-fed but not in HFD-fed mice, and there was an increased basal number of p-Akt positive cells in the ARC of DIO mice. These results suggest that the PDE3B-cAMP- and Akt-pathways of leptin signalling in the hypothalamus are impaired during the development of DIO. Thus, a defect in the regulation by leptin of the hypothalamic PDE3B-cAMP pathway and Akt signalling may be one of the mechanisms of central leptin resistance and the development of DIO.
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Affiliation(s)
- M Sahu
- Department of Obstetrics, Gynecology and Reproductive Sciences, Magee-Womens Research Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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43
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Anderson G, Rodriguez M. Multiple sclerosis: the role of melatonin and N-acetylserotonin. Mult Scler Relat Disord 2014; 4:112-23. [PMID: 25787187 DOI: 10.1016/j.msard.2014.12.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 11/06/2014] [Accepted: 12/09/2014] [Indexed: 12/31/2022]
Abstract
Multiple sclerosis (MS) is an immune mediated disorder that is under intensive investigation in an attempt to improve on available treatments. Many of the changes occurring in MS, including increased mitochondrial dysfunction, pain reporting and depression may be partly mediated by increased indoleamine 2,3-dioxygenase, which drives tryptophan to the production of neuroregulatory tryptophan catabolites and away from serotonin, N-acetylserotonin and melatonin production. The consequences of decreased melatonin have classically been attributed to circadian changes following its release from the pineal gland. However, recent data shows that melatonin may be produced by all mitochondria containing cells to some degree, including astrocytes and immune cells, thereby providing another important MS treatment target. As well as being a powerful antioxidant, anti-inflammatory and antinociceptive, melatonin improves mitochondrial functioning, partly via increased oxidative phosphorylation. Melatonin also inhibits demyelination and increases remyelination, suggesting that its local regulation in white matter astrocytes by serotonin availability and apolipoprotein E4, among other potential factors, will be important in the etiology, course and treatment of MS. Here we review the role of local melatonin and its precursors, N-acetylserotonin and serotonin, in MS.
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44
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Heldsinger A, Grabauskas G, Wu X, Zhou S, Lu Y, Song I, Owyang C. Ghrelin induces leptin resistance by activation of suppressor of cytokine signaling 3 expression in male rats: implications in satiety regulation. Endocrinology 2014; 155:3956-69. [PMID: 25060362 PMCID: PMC4164930 DOI: 10.1210/en.2013-2095] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The anorexigenic adipocyte-derived hormone leptin and the orexigenic hormone ghrelin act in opposition to regulate feeding behavior via the vagal afferent pathways. The mechanisms by which ghrelin exerts its inhibitory effects on leptin are unknown. We hypothesized that ghrelin activates the exchange protein activated by cAMP (Epac), inducing increased SOCS3 expression, which negatively affects leptin signal transduction and neuronal firing in nodose ganglia (NG) neurons. We showed that 91 ± 3% of leptin receptor (LRb) -bearing neurons contained ghrelin receptors (GHS-R1a) and that ghrelin significantly inhibited leptin-stimulated STAT3 phosphorylation in rat NG neurons. Studies of the signaling cascades used by ghrelin showed that ghrelin caused a significant increase in Epac and suppressor of cytokine signaling 3 (SOCS3) expression in cultured rat NG neurons. Transient transfection of cultured NG neurons to silence SOCS3 and Epac genes reversed the inhibitory effects of ghrelin on leptin-stimulated STAT3 phosphorylation. Patch-clamp studies and recordings of single neuronal discharges of vagal primary afferent neurons showed that ghrelin markedly inhibited leptin-stimulated neuronal firing, an action abolished by silencing SOCS3 expression in NG. Plasma ghrelin levels increased significantly during fasting. This was accompanied by enhanced SOCS3 expression in the NG and prevented by treatment with a ghrelin antagonist. Feeding studies showed that silencing SOCS3 expression in the NG reduced food intake evoked by endogenous leptin. We conclude that ghrelin exerts its inhibitory effects on leptin-stimulated neuronal firing by increasing SOCS3 expression. The SOCS3 signaling pathway plays a pivotal role in ghrelin's inhibitory effect on STAT3 phosphorylation, neuronal firing, and feeding behavior.
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Affiliation(s)
- Andrea Heldsinger
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48019
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45
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Xbp1s in Pomc neurons connects ER stress with energy balance and glucose homeostasis. Cell Metab 2014; 20:471-82. [PMID: 25017942 PMCID: PMC4186248 DOI: 10.1016/j.cmet.2014.06.002] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 05/20/2014] [Accepted: 05/29/2014] [Indexed: 01/14/2023]
Abstract
The molecular mechanisms underlying neuronal leptin and insulin resistance in obesity and diabetes remain unclear. Here we show that induction of the unfolded protein response transcription factor spliced X-box binding protein 1 (Xbp1s) in pro-opiomelanocortin (Pomc) neurons alone is sufficient to protect against diet-induced obesity as well as improve leptin and insulin sensitivity, even in the presence of strong activators of ER stress. We also demonstrate that constitutive expression of Xbp1s in Pomc neurons contributes to improved hepatic insulin sensitivity and suppression of endogenous glucose production. Notably, elevated Xbp1s levels in Pomc neurons also resulted in activation of the Xbp1s axis in the liver via a cell-nonautonomous mechanism. Together our results identify critical molecular mechanisms linking ER stress in arcuate Pomc neurons to acute leptin and insulin resistance as well as liver metabolism in diet-induced obesity and diabetes.
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46
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Stratigopoulos G, Martin Carli JF, O'Day DR, Wang L, Leduc CA, Lanzano P, Chung WK, Rosenbaum M, Egli D, Doherty DA, Leibel RL. Hypomorphism for RPGRIP1L, a ciliary gene vicinal to the FTO locus, causes increased adiposity in mice. Cell Metab 2014; 19:767-79. [PMID: 24807221 PMCID: PMC4131684 DOI: 10.1016/j.cmet.2014.04.009] [Citation(s) in RCA: 129] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 11/11/2013] [Accepted: 04/18/2014] [Indexed: 12/31/2022]
Abstract
Common polymorphisms in the first intron of FTO are associated with increased body weight in adults. Previous studies have suggested that a CUX1-regulatory element within the implicated FTO region controls expression of FTO and the nearby ciliary gene, RPGRIP1L. Given the role of ciliary genes in energy homeostasis, we hypothesized that mice hypomorphic for Rpgrip1l would display increased adiposity. We find that Rpgrip1l⁺/⁻ mice are hyperphagic and fatter, and display diminished suppression of food intake in response to leptin administration. In the hypothalamus of Rpgrip1l⁺/⁻ mice, and in human fibroblasts with hypomorphic mutations in RPGRIP1L, the number of AcIII-positive cilia is diminished, accompanied by impaired convening of the leptin receptor to the vicinity of the cilium, and diminished pStat3 in response to leptin. These findings suggest that RPGRIP1L may be partly or exclusively responsible for the obesity susceptibility signal at the FTO locus.
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Affiliation(s)
- George Stratigopoulos
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA.
| | - Jayne F Martin Carli
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | - Diana R O'Day
- Divisions of Developmental Medicine and Genetic Medicine, Department of Pediatrics, Seattle Children's Research Institute and University of Washington 1959 NE Pacific St, Seattle, WA 98195, USA
| | - Liheng Wang
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | - Charles A Leduc
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | - Patricia Lanzano
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | - Wendy K Chung
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | - Michael Rosenbaum
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | - Dieter Egli
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA
| | - Daniel A Doherty
- Divisions of Developmental Medicine and Genetic Medicine, Department of Pediatrics, Seattle Children's Research Institute and University of Washington 1959 NE Pacific St, Seattle, WA 98195, USA
| | - Rudolph L Leibel
- Naomi Berrie Diabetes Center and Division of Molecular Genetics, Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032, USA.
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47
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Almahariq M, Mei FC, Cheng X. Cyclic AMP sensor EPAC proteins and energy homeostasis. Trends Endocrinol Metab 2014; 25:60-71. [PMID: 24231725 PMCID: PMC3946731 DOI: 10.1016/j.tem.2013.10.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 09/30/2013] [Accepted: 10/11/2013] [Indexed: 12/16/2022]
Abstract
The pleiotropic second-messenger cAMP plays a crucial role in mediating the effects of various hormones on metabolism. The major intracellular functions of cAMP are transduced by protein kinase A (PKA) and by exchange proteins directly activated by cAMP (EPACs). The latter act as guanine-nucleotide exchange factors for the RAS-like small G proteins Rap1 and Rap2. Although the role of PKA in regulating energy balance has been extensively studied, the impact of EPACs remains relatively enigmatic. This review summarizes recent genetic and pharmacological studies concerning EPAC involvement in glucose homeostasis and energy balance via the regulation of leptin and insulin signaling pathways. In addition, the development of small-molecule EPAC-specific modulators and their therapeutic potential for the treatment of diabetes and obesity are discussed.
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Affiliation(s)
- Muayad Almahariq
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, Texas 77555-0615, USA
| | - Fang C Mei
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, Texas 77555-0615, USA; Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas 77030, USA
| | - Xiaodong Cheng
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, Texas 77555-0615, USA; Department of Integrative Biology and Pharmacology, The University of Texas Health Science Center, Houston, Texas 77030, USA.
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48
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Nadkarni P, Chepurny OG, Holz GG. Regulation of glucose homeostasis by GLP-1. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014. [PMID: 24373234 DOI: 10.1016/b978-0-12-800101-1.00002-8.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/01/2022]
Abstract
Glucagon-like peptide-1(7-36)amide (GLP-1) is a secreted peptide that acts as a key determinant of blood glucose homeostasis by virtue of its abilities to slow gastric emptying, to enhance pancreatic insulin secretion, and to suppress pancreatic glucagon secretion. GLP-1 is secreted from L cells of the gastrointestinal mucosa in response to a meal, and the blood glucose-lowering action of GLP-1 is terminated due to its enzymatic degradation by dipeptidyl-peptidase-IV (DPP-IV). Released GLP-1 activates enteric and autonomic reflexes while also circulating as an incretin hormone to control endocrine pancreas function. The GLP-1 receptor (GLP-1R) is a G protein-coupled receptor that is activated directly or indirectly by blood glucose-lowering agents currently in use for the treatment of type 2 diabetes mellitus (T2DM). These therapeutic agents include GLP-1R agonists (exenatide, liraglutide, lixisenatide, albiglutide, dulaglutide, and langlenatide) and DPP-IV inhibitors (sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin). Investigational agents for use in the treatment of T2DM include GPR119 and GPR40 receptor agonists that stimulate the release of GLP-1 from L cells. Summarized here is the role of GLP-1 to control blood glucose homeostasis, with special emphasis on the advantages and limitations of GLP-1-based therapeutics.
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Affiliation(s)
- Prashant Nadkarni
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA; Joslin Diabetes Center, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA
| | - Oleg G Chepurny
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA
| | - George G Holz
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA; Department of Pharmacology, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA.
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49
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Nadkarni P, Chepurny OG, Holz GG. Regulation of glucose homeostasis by GLP-1. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 121:23-65. [PMID: 24373234 DOI: 10.1016/b978-0-12-800101-1.00002-8] [Citation(s) in RCA: 156] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Glucagon-like peptide-1(7-36)amide (GLP-1) is a secreted peptide that acts as a key determinant of blood glucose homeostasis by virtue of its abilities to slow gastric emptying, to enhance pancreatic insulin secretion, and to suppress pancreatic glucagon secretion. GLP-1 is secreted from L cells of the gastrointestinal mucosa in response to a meal, and the blood glucose-lowering action of GLP-1 is terminated due to its enzymatic degradation by dipeptidyl-peptidase-IV (DPP-IV). Released GLP-1 activates enteric and autonomic reflexes while also circulating as an incretin hormone to control endocrine pancreas function. The GLP-1 receptor (GLP-1R) is a G protein-coupled receptor that is activated directly or indirectly by blood glucose-lowering agents currently in use for the treatment of type 2 diabetes mellitus (T2DM). These therapeutic agents include GLP-1R agonists (exenatide, liraglutide, lixisenatide, albiglutide, dulaglutide, and langlenatide) and DPP-IV inhibitors (sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin). Investigational agents for use in the treatment of T2DM include GPR119 and GPR40 receptor agonists that stimulate the release of GLP-1 from L cells. Summarized here is the role of GLP-1 to control blood glucose homeostasis, with special emphasis on the advantages and limitations of GLP-1-based therapeutics.
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Affiliation(s)
- Prashant Nadkarni
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA; Joslin Diabetes Center, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA
| | - Oleg G Chepurny
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA
| | - George G Holz
- Department of Medicine, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA; Department of Pharmacology, State University of New York (SUNY), Upstate Medical University, Syracuse, New York, USA.
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50
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Zhang Q, Liu B, Cheng Y, Meng Q, Xia T, Jiang L, Chen S, Liu Y, Guo F. Leptin signaling is required for leucine deprivation-enhanced energy expenditure. J Biol Chem 2013; 289:1779-87. [PMID: 24302741 DOI: 10.1074/jbc.m113.528943] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Leptin signaling in the hypothalamus is crucial in energy homeostasis. We have previously shown that dietary deprivation of the essential amino acid leucine in mice stimulates fat loss by increasing energy expenditure. The involvement of leptin signaling in this regulation, however, has not been reported. Here, we show that leucine deprivation promotes leptin signaling in mice maintained on an otherwise normal diet and restores leptin responses in mice maintained on a high fat diet, a regimen known to induce leptin resistance. In addition, we found that leucine deprivation stimulated energy expenditure, and fat loss was largely blocked in db/db mice homozygous for a mutation in leptin receptor and a knock-in mouse line Y3F with abrogation of leptin receptor Tyr(1138)-mediated signal transducer and activator transcript 3 signaling. Overall, our studies describe a novel link between hypothalamic leptin signaling and stimulation of energy expenditure under leucine deprivation.
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Affiliation(s)
- Qian Zhang
- From the Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China
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