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Pena-Leon V, Perez-Lois R, Villalon M, Prida E, Muñoz-Moreno D, Fernø J, Quiñones M, Al-Massadi O, Seoane LM. Novel mechanisms involved in leptin sensitization in obesity. Biochem Pharmacol 2024; 223:116129. [PMID: 38490517 DOI: 10.1016/j.bcp.2024.116129] [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: 11/16/2023] [Revised: 01/21/2024] [Accepted: 03/12/2024] [Indexed: 03/17/2024]
Abstract
Leptin is a hormone that is secreted by adipocytes in proportion to adipose tissue size, and that informs the brain about the energy status of the body. Leptin acts through its receptor LepRb, expressed mainly in the hypothalamus, and induces a negative energy balance by potent inhibition of feeding and activation of energy expenditure. These actions have led to huge expectations for the development of therapeutic targets for metabolic complications based on leptin-derived compounds. However, the majority of patients with obesity presents elevated leptin production, suggesting that in this setting leptin is ineffective in the regulation of energy balance. This resistance to the action of leptin in obesity has led to the development of "leptin sensitizers," which have been tested in preclinical studies. Much research has focused on generating combined treatments that act on multiple levels of the gastrointestinal-brain axis. The gastrointestinal-brain axis secretes a variety of different anorexigenic signals, such as uroguanylin, glucagon-like peptide-1, amylin, or cholecystokinin, which can alleviate the resistance to leptin action. Moreover, alternative mechanism such as pharmacokinetics, proteostasis, the role of specific kinases, chaperones, ER stress and neonatal feeding modifications are also implicated in leptin resistance. This review will cover the current knowledge regarding the interaction of leptin with different endocrine factors from the gastrointestinal-brain axis and other novel mechanisms that improve leptin sensitivity in obesity.
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Affiliation(s)
- Veronica Pena-Leon
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Raquel Perez-Lois
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Maria Villalon
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Eva Prida
- Translational Endocrinology group, Endocrinology Section, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (IDIS/CHUS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Diego Muñoz-Moreno
- Translational Endocrinology group, Endocrinology Section, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (IDIS/CHUS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain
| | - Johan Fernø
- Hormone Laboratory, Department of Biochemistry and Pharmacology, Haukeland University Hospital, 5201 Bergen, Norway
| | - Mar Quiñones
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; CIBER de Fisiopatología de la Obesidad y la Nutrición, Instituto de Salud Carlos III, Madrid, Spain
| | - Omar Al-Massadi
- Translational Endocrinology group, Endocrinology Section, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (IDIS/CHUS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; CIBER de Fisiopatología de la Obesidad y la Nutrición, Instituto de Salud Carlos III, Madrid, Spain.
| | - Luisa M Seoane
- Grupo Fisiopatología Endocrina, Departamento de Endocrinología, Instituto de Investigación Sanitaria de Santiago de Compostela, Complexo Hospitalario Universitario de Santiago (CHUS/SERGAS), Santiago de Compostela, Travesía da Choupana s/n, 15706 Santiago de Compostela, Spain; CIBER de Fisiopatología de la Obesidad y la Nutrición, Instituto de Salud Carlos III, Madrid, Spain.
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2
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Godieva V, Sammoura F, Verrier Paz S, Han Y, Di Guida V, Rishel MJ, Richardson JR, Chambers JW. Physiological JNK3 Concentrations Are Higher in Motor-related and Disease-implicated Brain Regions of C57BL6/J Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.17.575386. [PMID: 38293240 PMCID: PMC10827194 DOI: 10.1101/2024.01.17.575386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
The c-Jun N-terminal kinase 3 (JNK3) is a stress-responsive protein kinase primarily expressed in the central nervous system (CNS). JNK3 exhibits nuanced neurological activities, such as roles in behavior, circadian rhythms, and neurotransmission, but JNK3 is also implicated in cell death and neurodegeneration. Despite the critical role of JNK3 in neurophysiology and pathology, its localization in the brain is not fully understood due to a paucity of tools to distinguish JNK3 from other isoforms. While previous functional and histological studies suggest locales for JNK3 in the CNS, a comprehensive and higher resolution of JNK3 distribution and abundance remained elusive. Here, we sought to define the anatomical and cellular distribution of JNK3 in adult mouse brains. Data reveal the highest levels of JNK3 and pJNK3 were found in the cortex and the hippocampus. JNK3 possessed neuron-type selectivity as JNK3 was present in GABAergic, cholinergic, and dopaminergic neurons, but was not detectable in VGLUT-1-positive glutamatergic neurons and astrocytes in vivo . Intriguingly, higher JNK3 signals were found in motor neurons and relevant nuclei in the cortex, basal ganglia, brainstem, and spinal cord. While JNK3 was primarily observed in the cytosol of neurons in the cortex and the hippocampus, JNK3 appeared commonly within the nucleus in the brainstem. These distinctions suggest the potential for significant differences between JNK3 actions in distinct brain regions and cell types. Our results provide a significant improvement over previous reports of JNK3 spatial organization in the adult CNS and support continued investigation of JNK3's role in neurophysiology and pathophysiology.
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Szalanczy AM, Key CCC, Woods LCS. Genetic variation in satiety signaling and hypothalamic inflammation: merging fields for the study of obesity. J Nutr Biochem 2022; 101:108928. [PMID: 34936921 PMCID: PMC8959400 DOI: 10.1016/j.jnutbio.2021.108928] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/08/2021] [Accepted: 12/01/2021] [Indexed: 02/07/2023]
Abstract
Although obesity has been a longstanding health crisis, the genetic architecture of the disease remains poorly understood. Genome-wide association studies have identified many genomic loci associated with obesity, with genes being enriched in the brain, particularly in the hypothalamus. This points to the role of the central nervous system (CNS) in predisposition to obesity, and we emphasize here several key genes along the satiety signaling pathway involved in genetic susceptibility. Interest has also risen regarding the chronic, low-grade obesity-associated inflammation, with a growing concern toward inflammation in the hypothalamus as a precursor to obesity. Recent studies have found that genetic variation in inflammatory genes play a role in obesity susceptibility, and we highlight here several key genes. Despite the interest in the genetic variants of these pathways individually, there is a lack of research that investigates the relationship between the two. Understanding the interplay between genetic variation in obesity genes enriched in the CNS and inflammation genes will advance our understanding of obesity etiology and heterogeneity, improve genetic risk prediction analyses, and highlight new drug targets for the treatment of obesity. Additionally, this increased knowledge will assist in physician's ability to develop personalized nutrition and medication strategies for combating the obesity epidemic. Though it often seems to present universally, obesity is a highly individual disease, and there remains a need in the field to develop methods to treat at the individual level.
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Rehfeldt SCH, Laufer S, Goettert MI. A Highly Selective In Vitro JNK3 Inhibitor, FMU200, Restores Mitochondrial Membrane Potential and Reduces Oxidative Stress and Apoptosis in SH-SY5Y Cells. Int J Mol Sci 2021; 22:ijms22073701. [PMID: 33918172 PMCID: PMC8037381 DOI: 10.3390/ijms22073701] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 03/29/2021] [Accepted: 03/30/2021] [Indexed: 12/31/2022] Open
Abstract
Current treatments for neurodegenerative diseases (ND) are symptomatic and do not affect disease progression. Slowing this progression remains a crucial unmet need for patients and their families. c-Jun N-terminal kinase 3 (JNK3) are related to several ND hallmarks including apoptosis, oxidative stress, excitotoxicity, mitochondrial dysfunction, and neuroinflammation. JNK inhibitors can play an important role in addressing neuroprotection. This research aims to evaluate the neuroprotective, anti-inflammatory, and antioxidant effects of a synthetic compound (FMU200) with known JNK3 inhibitory activity in SH-SY5Y and RAW264.7 cell lines. SH-SY5Y cells were pretreated with FMU200 and cell damage was induced by 6-hydroxydopamine (6-OHDA) or hydrogen peroxide (H2O2). Cell viability and neuroprotective effect were assessed with an MTT assay. Flow cytometric analysis was performed to evaluate cell apoptosis. The H2O2-induced reactive oxygen species (ROS) generation and mitochondrial membrane potential (ΔΨm) were evaluated by DCFDA and JC-1 assays, respectively. The anti-inflammatory effect was determined in LPS-induced RAW264.7 cells by ELISA assay. In undifferentiated SH-SY5Y cells, FMU200 decreased neurotoxicity induced by 6-OHDA in approximately 20%. In RA-differentiated cells, FMU200 diminished cell death in approximately 40% and 90% after 24 and 48 h treatment, respectively. FMU200 reduced both early and late apoptotic cells, decreased ROS levels, restored mitochondrial membrane potential, and downregulated JNK phosphorylation after H2O2 exposure. In LPS-stimulated RAW264.7 cells, FMU200 reduced TNF-α levels after a 3 h treatment. FMU200 protects neuroblastoma SH-SY5Y cells against 6-OHDA- and H2O2-induced apoptosis, which may result from suppressing the JNK pathways. Our findings show that FMU200 can be a useful candidate for the treatment of neurodegenerative disorders.
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Affiliation(s)
| | - Stefan Laufer
- Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmacy, Eberhard Karls Universität Tübingen, D-72076 Tübingen, Germany
- Tübingen Center for Academic Drug Discovery (TüCAD2), D-72076 Tübingen, Germany
- Correspondence: (S.L.); (M.I.G.); Tel.: +55-(51)3714-7000 (ext. 5445) (M.I.G.)
| | - Márcia Inês Goettert
- Graduate Program in Biotechnology, University of Vale do Taquari (Univates), Lajeado, RS 95914-014, Brazil;
- Correspondence: (S.L.); (M.I.G.); Tel.: +55-(51)3714-7000 (ext. 5445) (M.I.G.)
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Abstract
Obesity, which has long since reached epidemic proportions worldwide, is associated with long-term stress to a variety of organs and results in diseases including type 2 diabetes. In the brain, overnutrition induces hypothalamic stress associated with the activation of several signalling pathways, together with central insulin and leptin resistance. This central action of nutrient overload appears very rapidly, suggesting that nutrition-induced hypothalamic stress is a major upstream initiator of obesity and associated diseases. The cellular response to nutrient overload includes the activation of the stress-activated c-Jun N-terminal kinases (JNKs) JNK1, JNK2 and JNK3, which are widely expressed in the brain. Here, we review recent findings on the regulation and effects of these kinases, with particular focus on the hypothalamus, a key brain region in the control of energy and glucose homeostasis. JNK1 blocks the hypothalamic-pituitary-thyroid axis, reducing energy expenditure and promoting obesity. Recently, opposing roles have been identified for JNK1 and JNK3 in hypothalamic agouti gene-related protein (AgRP) neurons: while JNK1 activation in AgRP neurons induces feeding and weight gain and impairs insulin and leptin signalling, JNK3 (also known as MAPK10) deletion in the same neuronal population produces very similar effects. The opposing roles of these kinases, and the unknown role of hypothalamic JNK2, reflect the complexity of JNK biology. Future studies should address the specific function of each kinase, not only in different neuronal subsets, but also in non-neuronal cells in the central nervous system. Decoding the puzzle of brain stress kinases will help to define the central stimuli and mechanisms implicated in the control of energy balance. Graphical abstract.
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Affiliation(s)
- Rubén Nogueiras
- 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, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Santiago de Compostela, Spain
- Galician Agency of Innovation (GAIN), Xunta de Galicia, Santiago de Compostela, Spain
| | - Guadalupe Sabio
- Department of Myocardial Pathophysiology, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain.
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Contreras-Chavez GG, Estrada JA, Contreras I. Changes in Appetite Regulation-Related Signaling Pathways in the Brain of Mice Supplemented with Non-nutritive Sweeteners. J Mol Neurosci 2020; 71:1144-1155. [PMID: 33128194 DOI: 10.1007/s12031-020-01737-y] [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] [Received: 08/19/2020] [Accepted: 10/19/2020] [Indexed: 10/23/2022]
Abstract
Non-nutritive sweeteners (NNSs) are commonly used to prevent weight gain and development of metabolic diseases associated with consumption of high-energy diets. Recent studies have demonstrated that these compounds may have unwanted detrimental effects under specific circumstances in vivo. In particular, an association between NNS consumption and changes in signaling pathways involved in the hunger-satiety system in the brain has been reported. Nonetheless, the extent of alterations in brain signaling pathways associated with consumption of these compounds has not been determined. The objective of this study was to determine the effect of frequent consumption of NNSs on the expression of proteins involved in signaling pathways related to appetite control in the brain in vivo. Eight-week-old BALB/c mice were supplemented with sucrose, sucralose, or steviol glycosides in their daily drinking water for 6 weeks. Subsequently, total brain protein extracts were used to analyze the expression of total and phosphorylated JAK2, STAT5, ERK 1/2, JNK, as well as SHP-2 and POMC, by western blot. Serum concentrations of leptin and α-MSH were quantified by ELISA. Results show that consumption of NNSs promotes significant changes in these signaling pathways, reducing the expression of pSTAT5/STAT5, pERK 1/2, SHP-2, and pJNK/JNK in male mice supplemented with steviol glycosides. Furthermore, consumption of steviol glycosides induced a decrease of α-MSH in male mice. In contrast, steviol glycosides induced overexpression of pSTAT5, pERK, and SHP-2 in females. These data suggest that chronic consumption of NNSs promotes sex-specific changes in signaling pathways related to the central hunger-satiety system in vivo.
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Affiliation(s)
- Gerson G Contreras-Chavez
- Laboratorio de Neuroquímica, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan S/N Esq. Jesús Carranza, Colonia Moderna de La Cruz, Estado de México, 50180, Toluca, Mexico
| | - José A Estrada
- Laboratorio de Neuroquímica, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan S/N Esq. Jesús Carranza, Colonia Moderna de La Cruz, Estado de México, 50180, Toluca, Mexico
| | - Irazú Contreras
- Laboratorio de Neuroquímica, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan S/N Esq. Jesús Carranza, Colonia Moderna de La Cruz, Estado de México, 50180, Toluca, Mexico.
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Role of c-Jun N-Terminal Kinases (JNKs) in Epilepsy and Metabolic Cognitive Impairment. Int J Mol Sci 2019; 21:ijms21010255. [PMID: 31905931 PMCID: PMC6981493 DOI: 10.3390/ijms21010255] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 12/17/2019] [Accepted: 12/20/2019] [Indexed: 01/08/2023] Open
Abstract
Previous studies have reported that the regulatory function of the different c-Jun N-terminal kinases isoforms (JNK1, JNK2, and JNK3) play an essential role in neurological disorders, such as epilepsy and metabolic-cognitive alterations. Accordingly, JNKs have emerged as suitable therapeutic strategies. In fact, it has been demonstrated that some unspecific JNK inhibitors exert antidiabetic and neuroprotective effects, albeit they usually show high toxicity or lack therapeutic value. In this sense, natural specific JNK inhibitors, such as Licochalcone A, are promising candidates. Nonetheless, research on the understanding of the role of each of the JNKs remains mandatory in order to progress on the identification of new selective JNK isoform inhibitors. In the present review, a summary on the current gathered data on the role of JNKs in pathology is presented, as well as a discussion on their potential role in pathologies like epilepsy and metabolic-cognitive injury. Moreover, data on the effects of synthetic small molecule inhibitors that modulate JNK-dependent pathways in the brain and peripheral tissues is reviewed.
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Sugar Promotes Feeding in Flies via the Serine Protease Homolog scarface. Cell Rep 2019; 24:3194-3206.e4. [PMID: 30232002 PMCID: PMC6167639 DOI: 10.1016/j.celrep.2018.08.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 05/08/2018] [Accepted: 08/21/2018] [Indexed: 11/24/2022] Open
Abstract
A balanced diet of macronutrients is critical for animal health. A lack of specific elements can have profound effects on behavior, reproduction, and lifespan. Here, we used Drosophila to understand how the brain responds to carbohydrate deprivation. We found that serine protease homologs (SPHs) are enriched among genes that are transcriptionally regulated in flies deprived of carbohydrates. Stimulation of neurons expressing one of these SPHs, Scarface (Scaf), or overexpression of scaf positively regulates feeding on nutritious sugars, whereas inhibition of these neurons or knockdown of scaf reduces feeding. This modulation of food intake occurs only in sated flies while hunger-induced feeding is unaffected. Furthermore, scaf expression correlates with the presence of sugar in the food. As Scaf and Scaf neurons promote feeding independent of the hunger state, and the levels of scaf are positively regulated by the presence of sugar, we conclude that scaf mediates the hedonic control of feeding. The fly brain responds to specific macronutrients via distinct signaling pathways Serine protease homologs act as neuromodulators under sugar deprivation Sugar is both necessary and sufficient to maintain expression levels of scarface Scarface and Scarface neurons mediate hedonic control of feeding in flies
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Folch J, Olloquequi J, Ettcheto M, Busquets O, Sánchez-López E, Cano A, Espinosa-Jiménez T, García ML, Beas-Zarate C, Casadesús G, Bulló M, Auladell C, Camins A. The Involvement of Peripheral and Brain Insulin Resistance in Late Onset Alzheimer's Dementia. Front Aging Neurosci 2019; 11:236. [PMID: 31551756 PMCID: PMC6743006 DOI: 10.3389/fnagi.2019.00236] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 08/15/2019] [Indexed: 12/15/2022] Open
Abstract
Nowadays, Alzheimer's disease (AD) is a severe sociological and clinical problem. Since it was first described, there has been a constant increase in its incidence and, for now, there are no effective treatments since current approved medications have only shown short-term symptomatic benefits. Therefore, it is imperative to increase efforts in the search for molecules and non-pharmacological strategies that are capable of slowing or stopping the progress of the disease and, ideally, to reverse it. The amyloid cascade hypothesis based on the fundamental role of amyloid has been the central hypothesis in the last 30 years. However, since amyloid-directed treatments have shown no relevant beneficial results other theories have been postulated to explain the origin of the pathology. The brain is a highly metabolically active energy-consuming tissue in the human body. It has an almost complete dependence on the metabolism of glucose and uses most of its energy for synaptic transmission. Thus, alterations on the utilization or availability of glucose may be cause for the appearance of neurodegenerative pathologies like AD. In this review article, the hypothesis known as Type 3 Diabetes (T3D) will be evaluated by summarizing some of the data that has been reported in recent years. According to published research, the adherence over time to low saturated fatty acids diets in the context of the Mediterranean diet would reduce the inflammatory levels in brain, with a decrease in the pro-inflammatory glial activation and mitochondrial oxidative stress. In this situation, the insulin receptor pathway would be able to fine tune the mitochondrial biogenesis in neuronal cells, regulation the adenosine triphosphate/adenosine diphosphate intracellular balance, and becoming a key factor involved in the preservation of the synaptic connexions and neuronal plasticity. In addition, new targets and strategies for the treatment of AD will be considered in this review for their potential as new pharmacological or non-pharmacological approaches.
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Affiliation(s)
- Jaume Folch
- Department of Biochemistry and Biotechnology, Faculty of Medicine and Health Sciences, University Rovira i Virgili (URV), Reus, Spain.,Berlin Institute of Health (BIH), Zoologisches Institut, Technische Universität Braunschweig, Braunschweig, Germany.,Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain
| | - Jordi Olloquequi
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Miren Ettcheto
- Department of Biochemistry and Biotechnology, Faculty of Medicine and Health Sciences, University Rovira i Virgili (URV), Reus, Spain.,Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Oriol Busquets
- Department of Biochemistry and Biotechnology, Faculty of Medicine and Health Sciences, University Rovira i Virgili (URV), Reus, Spain.,Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Elena Sánchez-López
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Unitat de Farmàcia, Tecnologia Farmacèutica i Fisico-Química, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), University of Barcelona, Barcelona, Spain
| | - Amanda Cano
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Unitat de Farmàcia, Tecnologia Farmacèutica i Fisico-Química, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), University of Barcelona, Barcelona, Spain
| | - Triana Espinosa-Jiménez
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
| | - Maria Luisa García
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Unitat de Farmàcia, Tecnologia Farmacèutica i Fisico-Química, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.,Institute of Nanoscience and Nanotechnology (IN2UB), University of Barcelona, Barcelona, Spain
| | - Carlos Beas-Zarate
- Laboratorio de Regeneración y Desarrollo Neural, Departamento de Biología Celular y Molecular, Instituto de Neurobiología, CUCBA, Guadalajar, México
| | - Gemma Casadesús
- Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Mónica Bulló
- Department of Biochemistry and Biotechnology, Faculty of Medicine and Health Sciences, University Rovira i Virgili (URV), Reus, Spain.,Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Carme Auladell
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y la Nutrición (CIBEROBN), Institute of Health Carlos III, Madrid, Spain
| | - Antoni Camins
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Institute of Health Carlos III, Madrid, Spain.,Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
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10
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Ettcheto M, Cano A, Busquets O, Manzine PR, Sánchez-López E, Castro-Torres RD, Beas-Zarate C, Verdaguer E, García ML, Olloquequi J, Auladell C, Folch J, Camins A. A metabolic perspective of late onset Alzheimer's disease. Pharmacol Res 2019; 145:104255. [PMID: 31075308 DOI: 10.1016/j.phrs.2019.104255] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 03/11/2019] [Accepted: 04/30/2019] [Indexed: 12/13/2022]
Abstract
After decades of research, the molecular neuropathology of Alzheimer's disease (AD) is still one of the hot topics in biomedical sciences. Some studies suggest that soluble amyloid β (Aβ) oligomers act as causative agents in the development of AD and could be initiators of its complex neurodegenerative cascade. On the other hand, there is also evidence pointing to Aβ oligomers as mere aggravators, with an arguable role in the origin of the disease. In this line of research, the relative contribution of soluble Aβ oligomers to neuronal damage associated with metabolic disorders such as Type 2 Diabetes Mellitus (T2DM) and obesity is being actively investigated. Some authors have proposed the endoplasmic reticulum (ER) stress and the induction of the unfolded protein response (UPR) as important mechanisms leading to an increase in Aβ production and the activation of neuroinflammatory processes. Following this line of thought, these mechanisms could also cause cognitive impairment. The present review summarizes the current understanding on the neuropathological role of Aβ associated with metabolic alterations induced by an obesogenic high fat diet (HFD) intake. It is believed that the combination of these two elements has a synergic effect, leading to the impairement of ER and mitochondrial functions, glial reactivity status alteration and inhibition of insulin receptor (IR) signalling. All these metabolic alterations would favour neuronal malfunction and, eventually, neuronal death by apoptosis, hence causing cognitive impairment and laying the foundations for late-onset AD (LOAD). Moreover, since drugs enhancing the activation of cerebral insulin pathway can constitute a suitable strategy for the prevention of AD, we also discuss the scope of therapeutic approaches such as intranasal administration of insulin in clinical trials with AD patients.
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Affiliation(s)
- Miren Ettcheto
- Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Departament de Bioquímica i Biotecnologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Amanda Cano
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain; Unitat de Farmàcia, Tecnologia Farmacèutica i Fisico-química, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | - Oriol Busquets
- Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Departament de Bioquímica i Biotecnologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Patricia Regina Manzine
- Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain; Department of Gerontology, Federal University of São Carlos (UFSCar), São Carlos, SP, Brazil
| | - Elena Sánchez-López
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain; Unitat de Farmàcia, Tecnologia Farmacèutica i Fisico-química, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | - Rubén D Castro-Torres
- Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain; Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Laboratorio de Regeneración y Desarrollo Neural, Instituto de Neurobiología, Departamento de Biología Celular y Molecular, CUCBA, Mexico
| | - Carlos Beas-Zarate
- Laboratorio de Regeneración y Desarrollo Neural, Instituto de Neurobiología, Departamento de Biología Celular y Molecular, CUCBA, Mexico
| | - Ester Verdaguer
- Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain; Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - María Luisa García
- Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain; Unitat de Farmàcia, Tecnologia Farmacèutica i Fisico-química, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Institute of Nanoscience and Nanotechnology (IN2UB), Universitat de Barcelona, Spain
| | - Jordi Olloquequi
- Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Talca, Chile
| | - Carme Auladell
- Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain; Departament de Biologia Cel·lular, Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Jaume Folch
- Departament de Bioquímica i Biotecnologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Antoni Camins
- Departament de Farmacologia, Toxicologia i Química Terapèutica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona, Barcelona, Spain; Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain; Biomedical Research Networking Centre in Neurodegenerative Diseases (CIBERNED), Madrid, Spain.
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11
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Cakir I, Nillni EA. Endoplasmic Reticulum Stress, the Hypothalamus, and Energy Balance. Trends Endocrinol Metab 2019; 30:163-176. [PMID: 30691778 DOI: 10.1016/j.tem.2019.01.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 12/17/2018] [Accepted: 01/03/2019] [Indexed: 01/09/2023]
Abstract
Overweight and obesity pose significant health problems globally, and are causatively linked to metabolic dysregulation. The hypothalamus integrates neural, nutritional, and hormonal cues to regulate homeostasis, including circadian rhythm, body temperature, thirst, food intake, energy expenditure, and glucose metabolism. Hypothalamic neuropeptides play a fundamental role in these processes. Studies during the past two decades suggest a role of central endoplasmic reticulum (ER) stress in the pathophysiology of obesity. This review covers recent findings on the role of ER stress and neuropeptide processing in the central regulation of energy homeostasis, with special emphasis on proopiomelanocortin (POMC)-encoding neurons. In addition, the role of neuroinflammation in the context of obesity is briefly discussed.
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Affiliation(s)
- Isin Cakir
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Eduardo A Nillni
- Department of Medicine, Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI 02912, USA.
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12
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Sima N, Sun W, Gorshkov K, Shen M, Huang W, Zhu W, Xie X, Zheng W, Cheng X. Small Molecules Identified from a Quantitative Drug Combinational Screen Resensitize Cisplatin's Response in Drug-Resistant Ovarian Cancer Cells. Transl Oncol 2018; 11:1053-1064. [PMID: 29982103 PMCID: PMC6034569 DOI: 10.1016/j.tranon.2018.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Revised: 06/10/2018] [Accepted: 06/11/2018] [Indexed: 12/29/2022] Open
Abstract
Drug resistance to chemotherapy occurs in many ovarian cancer patients resulting in failure of treatment. Exploration of drug resistance mechanisms and identification of new therapeutics that overcome the drug resistance can improve patient prognosis. Following a quantitative combination screen of 6060 approved drugs and bioactive compounds in a cisplatin-resistant A2780-cis ovarian cancer cell line, 38 active compounds with IC50s under 1 μM suppressed the growth of cisplatin-resistant ovarian cancer cells. Among these confirmed compounds, CUDC-101, OSU-03012, oligomycin A, VE-821, or Torin2 in a combination with cisplatin restored cisplatin's apoptotic response in the A2780-cis cells, while SR-3306, GSK-923295, SNX-5422, AT-13387, and PF-05212384 directly suppressed the growth of A2780-cis cells. One of the mechanisms for overcoming cisplatin resistance in these cells is mediated by the inhibition of epidermal growth factor receptor (EGFR), though not all the EGFR inhibitors are equally active. The increased levels of total EGFR and phosphorylated-EGFR (p-EGFR) in the A2780-cis cells were reduced after the combined treatment of cisplatin with EGFR inhibitors. In addition, a knockdown of EGFR mRNA reduced cisplatin resistance in the A2780-cis cells. Therefore, the top active compounds identified in this work can be studied further as potential treatments for cisplatin-resistant ovarian cancer. The quantitative combinational screening approach is a useful method for identifying effective compounds and drug combinations against drug-resistant cancer cells.
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Affiliation(s)
- Ni Sima
- Department of Gynecologic Oncology, Women's Reproductive Health Laboratory of Zhejiang Province, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China; National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Wei Sun
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Kirill Gorshkov
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Min Shen
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Wei Huang
- Department of Gynecologic Oncology, Women's Reproductive Health Laboratory of Zhejiang Province, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China; National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA
| | - Wenge Zhu
- Department of Biochemistry and Molecular Biology, The George Washington University Medical School, Washington, DC
| | - Xing Xie
- Department of Gynecologic Oncology, Women's Reproductive Health Laboratory of Zhejiang Province, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China
| | - Wei Zheng
- National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, MD, USA.
| | - Xiaodong Cheng
- Department of Gynecologic Oncology, Women's Reproductive Health Laboratory of Zhejiang Province, Women's Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, PR China.
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13
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Holubová M, Hrubá L, Neprašová B, Majerčíková Z, Lacinová Z, Kuneš J, Maletínská L, Železná B. Prolactin-releasing peptide improved leptin hypothalamic signaling in obese mice. J Mol Endocrinol 2018; 60:85-94. [PMID: 29233862 DOI: 10.1530/jme-17-0171] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 12/11/2017] [Indexed: 11/08/2022]
Abstract
The situation following anti-obesity drug termination is rarely investigated, eventhough a decrease in body weight needs to be sustained. Therefore, this study examined the impact of twice-daily peripheral administration of 5 mg/kg [N-palm-γGlu-Lys11] prolactin-releasing peptide 31 (palm11-PrRP31) in mice with diet-induced obesity (DIO from consuming a high-fat diet) after 28 days of treatment (palm11-PrRP31 group) and after 14 days of peptide treatment followed by 14 days of discontinuation (palm11-PrRP31 + saline group). At the end of the treatment, cumulative food intake, body weight and subcutaneous fat weight/body weight ratio and leptin plasma level were reduced significantly in both the palm11-PrRP31 group and the palm11-PrRP31 + saline group compared to the saline control group. This reduction correlated with significantly increased FOSB, a marker of long-term neuronal potentiation, in the nucleus arcuatus and nucleus tractus solitarii, areas known to be affected by the anorexigenic effect of palm11-PrRP31. Moreover, activation of leptin-related hypothalamic signaling was registered through an increase in phosphoinositide-3-kinase, increased phosphorylation of protein kinase B (PKB, AKT) and enhanced extracellular signal-regulated kinase 1/2 phosphorylation. Besides, lowered apoptotic markers c-JUN N-terminal kinase and c-JUN phosphorylation were registered in the hypothalami of both palm11-PrRP31-treated groups. This study demonstrates that palm11-PrRP31 positively affects feeding and leptin-related hypothalamic signaling, not only after 28 days of treatment but even 14 days after the termination of a 14-day long treatment without the yo-yo effect.
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Affiliation(s)
- Martina Holubová
- Institute of Organic Chemistry and BiochemistryThe Czech Academy of Sciences, Czech Republic
| | - Lucie Hrubá
- Institute of Organic Chemistry and BiochemistryThe Czech Academy of Sciences, Czech Republic
| | - Barbora Neprašová
- Institute of Organic Chemistry and BiochemistryThe Czech Academy of Sciences, Czech Republic
- Institute of PhysiologyThe Czech Academy of Sciences, Prague, Czech Republic
| | - Zuzana Majerčíková
- Institute of Organic Chemistry and BiochemistryThe Czech Academy of Sciences, Czech Republic
| | - Zdeňka Lacinová
- Institute for Clinical and Experimental MedicinePrague, Czech Republic
- First Faculty of MedicineCharles University in Prague and General University Hospital, Prague, Czech Republic
| | - Jaroslav Kuneš
- Institute of Organic Chemistry and BiochemistryThe Czech Academy of Sciences, Czech Republic
- Institute of PhysiologyThe Czech Academy of Sciences, Prague, Czech Republic
| | - Lenka Maletínská
- Institute of Organic Chemistry and BiochemistryThe Czech Academy of Sciences, Czech Republic
| | - Blanka Železná
- Institute of Organic Chemistry and BiochemistryThe Czech Academy of Sciences, Czech Republic
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14
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Goetzman ES, Gong Z, Schiff M, Wang Y, Muzumdar RH. Metabolic pathways at the crossroads of diabetes and inborn errors. J Inherit Metab Dis 2018; 41:5-17. [PMID: 28952033 PMCID: PMC6757345 DOI: 10.1007/s10545-017-0091-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/30/2017] [Accepted: 09/08/2017] [Indexed: 12/18/2022]
Abstract
Research over the past two decades has led to advances in our understanding of the genetic and metabolic factors that underlie the pathogenesis of type 2 diabetes mellitus (T2DM). While T2DM is defined by its hallmark metabolic symptoms, the genetic risk factors for T2DM are more immune-related than metabolism-related, and the observed metabolic disease may be secondary to chronic inflammation. Regardless, these metabolic changes are not benign, as the accumulation of some metabolic intermediates serves to further drive the inflammation and cell stress, eventually leading to insulin resistance and ultimately to T2DM. Because many of the biochemical changes observed in the pre-diabetic state (i.e., ectopic lipid storage, increased acylcarnitines, increased branched-chain amino acids) are also observed in patients with rare inborn errors of fatty acid and amino acid metabolism, an interesting question is raised regarding whether isolated metabolic gene defects can confer an increased risk for T2DM. In this review, we attempt to address this question by summarizing the literature regarding the metabolic pathways at the crossroads of diabetes and inborn errors of metabolism. Studies using cell culture and animal models have revealed that, within a given pathway, disrupting some genes can lead to insulin resistance while for others there may be no effect or even improved insulin sensitivity. This differential response to ablating a single metabolic gene appears to be dependent upon the specific metabolic intermediates that accumulate and whether these intermediates subsequently activate inflammatory pathways. This highlights the need for future studies to determine whether certain inborn errors may confer increased risk for diabetes as the patients age.
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Affiliation(s)
- Eric S Goetzman
- Department of Pediatrics, School of Medicine, University of Pittsburgh, 4401 Penn Ave, Pittsburgh, PA, 15224, USA.
- Children's Hospital of Pittsburgh, Rangos 5117, 4401 Penn Avenue, Pittsburgh, PA, 15224, USA.
| | - Zhenwei Gong
- Department of Pediatrics, School of Medicine, University of Pittsburgh, 4401 Penn Ave, Pittsburgh, PA, 15224, USA
| | - Manuel Schiff
- UMR1141, PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
- Reference Center for Inborn Errors of Metabolism, Robert Debré University Hospital, APHP, Paris, France
| | - Yan Wang
- Department of Pediatrics, School of Medicine, University of Pittsburgh, 4401 Penn Ave, Pittsburgh, PA, 15224, USA
| | - Radhika H Muzumdar
- Department of Pediatrics, School of Medicine, University of Pittsburgh, 4401 Penn Ave, Pittsburgh, PA, 15224, USA
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15
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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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LPS-Induced Low-Grade Inflammation Increases Hypothalamic JNK Expression and Causes Central Insulin Resistance Irrespective of Body Weight Changes. Int J Mol Sci 2017; 18:ijms18071431. [PMID: 28677618 PMCID: PMC5535922 DOI: 10.3390/ijms18071431] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 06/22/2017] [Accepted: 06/27/2017] [Indexed: 01/26/2023] Open
Abstract
Metabolic endotoxemia contributes to low-grade inflammation in obesity, which causes insulin resistance due to the activation of intracellular proinflammatory pathways, such as the c-Jun N-terminal Kinase (JNK) cascade in the hypothalamus and other tissues. However, it remains unclear whether the proinflammatory process precedes insulin resistance or it appears because of the development of obesity. Hypothalamic low-grade inflammation was induced by prolonged lipopolysaccharide (LPS) exposure to investigate if central insulin resistance is induced by an inflammatory stimulus regardless of obesity. Male Wistar rats were treated with single (1 LPS) or repeated injections (6 LPS) of LPS (100 μg/kg, IP) to evaluate the phosphorylation of the insulin receptor substrate-1 (IRS1), Protein kinase B (AKT), and JNK in the hypothalamus. Single LPS increased the expression of pIRS1, pAKT, and pJNK, whereas the repeated LPS treatment failed to recruit pIRS1 and pAKT. The 6 LPS treated rats showed increased total JNK and pJNK. The 6 LPS rats became unresponsive to the hypophagic effect induced by central insulin administration (12 μM/5 μL, ICV). Prolonged exposure to LPS (24 h) impaired the insulin-induced AKT phosphorylation and the translocation of the transcription factor forkhead box protein O1 (FoxO1) from the nucleus to the cytoplasm of the cultured hypothalamic GT1-7 cells. Central administration of the JNK inhibitor (20 μM/5 μL, ICV) restored the ability of insulin to phosphorylate IRS1 and AKT in 6 LPS rats. The present data suggest that an increased JNK activity in the hypothalamus underlies the development of insulin resistance during prolonged exposure to endotoxins. Our study reveals that weight gain is not mandatory for the development of hypothalamic insulin resistance and the blockade of proinflammatory pathways could be useful for restoring the insulin signaling during prolonged low-grade inflammation as seen in obesity.
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Adiponectin deficiency rescues high-fat diet-induced hepatic injury, apoptosis and autophagy loss despite persistent steatosis. Int J Obes (Lond) 2017; 41:1403-1412. [PMID: 28559541 DOI: 10.1038/ijo.2017.128] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 05/01/2017] [Accepted: 05/16/2017] [Indexed: 02/06/2023]
Abstract
Background &aims:Low levels of adiponectin (APN), an adipose-derived adipokine, are associated with obesity and non-alcoholic steatohepatitis although its role in high-fat diet-induced hepatic injury and steatosis remains unclear. Here we hypothesized that APN deficiency alters fat diet-induced hepatic function. To this end, we examined the effect of APN deficiency on high-fat diet-induced hepatic injury, apoptosis and steatosis. METHODS Adult wild type and APN knockout mice were fed a low- or high-fat diet for 20 weeks. Serum levels of liver enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), cholesterol, hepatic triglycerides, steatosis, pro-inflammatory cytokines, apoptosis and autophagy were examined. RESULTS High-fat feeding led to elevated body (48.2%) and liver weights (18.8%), increased levels of ALT (87.8%), serum cholesterol (104.4%), hepatic triglycerides (305.6%) and hepatic fat deposition as evidenced by Oil Red O staining, along with a reduced AST/ALT ratio and unchanged AST. Although APN knockout itself did not affect hepatic function and morphology, it reconciled fat diet-induced hepatic injury (P<0.05 vs WT-HF group) without reversing changes in body and liver weights, serum cholesterol and hepatic steatosis. In addition, fat diet intake promoted AMPK phosphorylation, p62 accumulation and apoptosis, including elevated Bax and cleaved Caspase-3 and downregulated Bcl-2, along with suppressed phosphorylation of Akt, STAT3 and JNK, and the autophagy makers Atg7, Beclin-1 and LC3B (P<0.05 vs WT-LF group) without affecting hepatic interlelukin-6 and tumor necrosis factor-α levels, the effects were reversed or significantly attenuated by APN knockout (P<0.05 vs WT-HF group). In vitro study using HepG2 cells revealed that STAT3 activation rescued palmitic acid-induced cell injury whereas STAT3 inhibition nullified APN knockdown-offered beneficial effects. CONCLUSIONS Our results revealed that high-fat diet intake promotes hepatic steatosis, apoptosis and interrupted autophagy. APN knockout elicits protective effect against hepatic injury possibly associated with autophagy regulation despite persistent hepatic steatosis.
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