leptin has been researched along with Neuroblastoma* in 15 studies
15 other study(ies) available for leptin and Neuroblastoma
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Lipoxin A4 methyl ester attenuated ketamine-induced neurotoxicity in SH-SY5Y cells via regulating leptin pathway.
Ketamine, the widely used intravenous anesthetic, has been reported to cause neurotoxicity and disturbs normal neurogenesis. However, the efficacy of current treatment strategies targeting ketamine's neurotoxicity remains limited. Lipoxin A4 methyl ester (LXA4 ME) is relatively stable lipoxin analog, which serves an important role in protecting against early brain injury. The purpose of this study was to investigate the protective effect of LXA4 ME on ketamine-caused cytotoxicity in SH-SY5Y cells, as well as the underlying mechanisms. Cell viability, apoptosis and endoplasmic reticulum stress (ER stress) were detected by adopting experimental techniques including CCK-8 assay, flow cytometry, western blotting and transmission electron microscope. Furthermore, examining the expression of leptin and its receptor (LepRb), we also measured the levels of activation of the leptin signaling pathway. Our results showed that LXA4 ME intervention promoted the cell viability, inhibited cell apoptosis, and reduced the expression of ER stress related protein and morphological changes induced by ketamine. In addition, inhibition of leptin signaling pathway caused by ketamine could be reversed by LXA4 ME. However, as the specific inhibitor of leptin pathway, leptin antagonist triple mutant human recombinant (leptin tA) attenuated the cytoprotective effect of LXA4 ME against ketamine-induced neurotoxicity. In conclusion, our findings demonstrated LXA4 ME could exert a neuroprotective effect on ketamine-induced neuronal injury via activation of the leptin signaling pathway. Topics: Humans; Ketamine; Leptin; Lipoxins; Neuroblastoma | 2023 |
Homocysteine causes neuronal leptin resistance and endoplasmic reticulum stress.
Abnormally high serum homocysteine levels have been associated with several disorders, including obesity, cardiovascular diseases or neurological diseases. Leptin is an anti-obesity protein and its action is mainly mediated by the activation of its Ob-R receptor in neuronal cells. The inability of leptin to induce activation of its specific signaling pathways, especially under endoplasmic reticulum stress, leads to the leptin resistance observed in obesity. The present study examined the effect of homocysteine on leptin signaling in SH-SY5Y neuroblastoma cells expressing the leptin receptor Ob-Rb. Phosphorylation of the signal transducer and activator of transcription (STAT3) and leptin-induced STAT3 transcriptional activity were significantly inhibited by homocysteine treatment. These effects may be specific to homocysteine and to the leptin pathway, as other homocysteine-related compounds, namely methionine and cysteine, have weak effect on leptin-induced inhibition of STAT3 phosphorylation, and homocysteine has no impact on IL-6-induced activation of STAT3. The direct effect of homocysteine on leptin-induced Ob-R activation, analyzed by Ob-R BRET biosensor to monitor Ob-R oligomerization and conformational change, suggested that homocysteine treatment does not affect early events of leptin-induced Ob-R activation. Instead, we found that, unlike methionine or cysteine, homocysteine increases the expression of the endoplasmic reticulum (ER) stress response gene, a homocysteine-sensitive ER resident protein. These results suggest that homocysteine may induce neuronal resistance to leptin by suppressing STAT3 phosphorylation downstream of the leptin receptor via ER stress. Topics: Cysteine; Endoplasmic Reticulum Stress; Homocysteine; Humans; Leptin; Methionine; Neuroblastoma; Obesity; Receptors, Leptin; STAT3 Transcription Factor | 2022 |
Leptin Chronic Effect on Differentiation, Ion Currents and Protein Expression in N1E-115 Neuroblastoma Cells.
<b>Background and Objective:</b> Arcuate nucleus (ARC), a component of appetite-regulatory factors, contains populations of both orexigenic and anorexigenic neurons and one of the fundamental components of its system is leptin. Studies have evidenced the critical neurotrophic role in the development of ARC. To determine such effects on neuron development, N1E-115 neuroblastoma cells were used as an ARC model. <b>Materials and Methods:</b> N1E-115 neuroblastoma cells were treated with leptin [10 nM] for 24, 48 and 72 hrs. Dimethyl sulfoxide (DMSO) 1.5% was used as a known drug that promotes neurite expression. Cells percentage (%) that developed neurites was evaluated by bright field microscopy. Patch-clamp electrophysiology was used to analyze membrane ion currents, RT-PCR for quantifying changes in mRNA expression of anorexic peptides, proopiomelanocortin (POMC) and cocaine and amphetamine-related transcript (CART), in addition to principal Na<sub>v</sub>, Ca<sub>v</sub> ion channel subunits. <b>Results:</b> N1E-115 cells treated with leptin show neurite expression after 24 hrs of treatment, similar effects were obtained with DMSO. Leptin (time-dependent) increases the inward current in comparison with the control value at 72 hrs. Outward currents were not affected by leptin. Leptin and DMSO increased Na<sup>+</sup> and Ca<sup>2+</sup> current without changes in the kinetic properties. Lastly, leptin promotes an increase in mRNA level expression of transcripts to POMC, CART, Na<sub>v</sub>1.2 and Ca<sub>v</sub>1.3. <b>Conclusion:</b> Leptin chronic treatment promotes neurite expression, Up-regulation of Na<sup>+</sup> and Ca<sup>2+</sup> ion channels determining neuronal excitability, besides increasing the mRNA level expression of anorexic peptides POMC and CART in neuroblastoma N1E-115. Topics: Animals; Cell Differentiation; Disease Models, Animal; Gene Expression; Ion Channels; Leptin; Mexico; Mice; Neuroblastoma | 2021 |
Hyperleucinemia causes hippocampal retromer deficiency linking diabetes to Alzheimer's disease.
Type 2 diabetes (T2D) is a major risk factor for late-onset Alzheimer's disease (AD). A variety of metabolic changes related to T2D (e.g. hyperinsulinemia, hyperglycemia, and elevated branched-chain amino acids) have been proposed as mechanistic links, but the basis for this association remains unknown. Retromer-dependent trafficking is implicated in the pathogenesis of AD, and two key retromer proteins, VPS35 and VPS26, are deficient in the hippocampal formation of AD patients. We characterized VPS35 levels in five different mouse models of T2D/obesity to identify specific metabolic factors that could affect retromer levels in the brain. Mouse models in which hyperleucinemia was present displayed hippocampus-selective retromer deficiency. Wild-type lean mice fed a high leucine diet also developed hippocampal-selective retromer deficiency, and neuronal-like cells grown in high ambient leucine had reduced retromer complex proteins. Our results suggest that hyperleucinemia may account, in part, for the association of insulin resistance/T2D with AD. Topics: Alzheimer Disease; Analysis of Variance; Animals; Cell Line, Tumor; Diabetes Mellitus, Type 2; Disease Progression; Enzyme-Linked Immunosorbent Assay; Glucose Tolerance Test; Hippocampus; Humans; Leptin; Leucine; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neuroblastoma; Vesicular Transport Proteins | 2014 |
SOCS3 and SOCS6 are required for the risperidone-mediated inhibition of insulin and leptin signaling in neuroblastoma cells.
Antipsychotic drugs are regularly used for the treatment of many types of psychiatric disorders. The administration of second-generation antipsychotics is often associated with weight gain and the development of diabetes mellitus; however, the molecular mechanisms underlying the effects of these drugs remain poorly understood. Leptin and insulin play key roles in the regulation of energy balance and glucose homeostasis, and resistance to the actions of these hormones can occur with obesity and inflammation, resulting in the pathogenesis of obesity and type 2 diabetes. In this study, the effects of risperidone on the insulin-induced protein kinase B (PKB) phosphorylation and leptin-stimulated signal transducer and activator of transcription 3 (STAT3) phosphorylation were investigated in the human SH-SY5Y neuroblastoma cell line. The treatment of these cells with risperidone induced the activation of extracellular signal-related kinase (ERK) by cellular cyclic adenosine 3-monophosphate (cAMP)-dependent protein kinase (also known as protein kinase A; PKA) and the mechanisms involved include the induction of suppressor of cytokine signaling 3 (SOCS3) and suppressor of cytokine signaling 6 (SOCS6) expression. The risperidone-induced ERK activation induced an upregulation of SOCS3 and SOCS6 mRNA expression levels. Taken together, these results suggest that risperidone modulates SOCS3 and SOCS6 expression through adenylate cyclase-mediated ERK activation, which, in turn, leads to an inhibition of insulin-induced PKB phosphorylation and leptin-stimulated STAT3 phosphorylation. Eventually, these effects result in excessive body weight gain due to the inhibition of both the leptin and insulin signaling pathways. Topics: Cell Line, Tumor; Humans; Insulin; Leptin; Neuroblastoma; Phosphorylation; Risperidone; Signal Transduction; STAT3 Transcription Factor; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins | 2014 |
Leptin attenuates BACE1 expression and amyloid-β genesis via the activation of SIRT1 signaling pathway.
The aspartyl protease β-site AβPP-cleaving enzyme 1 (BACE1) catalyzes the rate-limiting step in Aβ production, a peptide at the nexus of neurodegenerative cascades in Alzheimer Disease (AD). The adipocytokine leptin has been demonstrated to reduce Aβ production and decrease BACE1 activity and expression levels. However, the signaling cascades involved in the leptin-induced mitigation in Aβ levels and BACE1 expression levels have not been elucidated. We have demonstrated that the transcription factor nuclear factor - kappa B (NF-κB) positively regulates BACE1 transcription. NF-κB activity is tightly regulated by the mammalian sirtuin SIRT1. Multiple studies have cogently evinced that leptin activates the metabolic master regulator SIRT1. In this study, we determined the extent to which SIRT1 expression and activity regulate the leptin-induced attenuation in BACE1 expression and Aβ levels in cultured human neuroblastoma SH-SY5Y cells. This study also elucidated and delineated the signal transduction pathways involved in the leptin induced mitigation in BACE1 expression. Our results demonstrate for the first time that leptin attenuates the activation and transcriptional activity of NF-κB by reducing the acetylation of the p65 subunit in a SIRT1-dependent manner. Furthermore, our data shows that leptin reduces the NF-κB-mediated transcription of BACE1 and consequently reduces Amyloid-β genesis. Our study provides a valuable insight and a novel mechanism by which leptin reduces BACE1 expression and Amyloid-β production and may help design potential therapeutic interventions. Topics: Amyloid beta-Peptides; Amyloid Precursor Protein Secretases; Aspartic Acid Endopeptidases; Blotting, Western; Chromatin Immunoprecipitation; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation, Neoplastic; Humans; Leptin; Neuroblastoma; NF-kappa B; Promoter Regions, Genetic; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Sirtuin 1; Tumor Cells, Cultured | 2014 |
Endoplasmic reticulum stress-induced CHOP activation mediates the down-regulation of leptin in human neuroblastoma SH-SY5Y cells treated with the oxysterol 27-hydroxycholesterol.
Epidemiological studies have suggested an inverse relationship between the adipocytokine leptin and the onset of Alzheimer's disease (AD), and leptin supplementation decreases amyloid-β (Aβ) production and tau phosphorylation (p-tau), two major biochemical events that play a key role in the pathogenesis of AD. We have previously shown that the cholesterol oxidized product 27-hydroxycholesterol (27-OHC) inhibits leptin expression, an effect that correlated with increased levels of Aβ and p-tau. We have also shown that 27-OHC induces endoplasmic reticulum (ER) stress, a cellular response that is implicated in AD and confers leptin resistance. However the extent to which ER stress is involved in 27-OHC-induced attenuation in leptin expression has not been determined. In this study we determined the involvement of ER stress in the 27-OHC-induced attenuation of leptin expression in SH-SY5Y human neuroblastoma cells. We demonstrate that 27-OHC-induced ER stress attenuates leptin expression by activating C/EBP Homologous Protein (CHOP) which negatively regulates C/EBPα, a transcription factor required for leptin expression. The molecular chaperone 4-phenylbutyric acid (4-PBA) precludes 27-OHC-evoked ER stress and down-regulation of leptin. Furthermore, we demonstrate that the activation of the transcription factor CHOP in response to ER stress is pivotal in the attenuation of leptin expression as knocking-down CHOP alleviates the attenuation in leptin expression. Our study implicates ER stress as the mechanistic link in the 27-OHC-induced negative regulation of leptin, a hormone that has potential therapeutic effects in AD by reducing Aβ and phosphorylated tau accumulation. Topics: Alzheimer Disease; Amyloid beta-Peptides; Cell Line, Tumor; Electrophoretic Mobility Shift Assay; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Gene Expression Regulation; Humans; Hydroxycholesterols; Leptin; Neuroblastoma; Phosphorylation; Real-Time Polymerase Chain Reaction; RNA, Small Interfering; Signal Transduction; tau Proteins; Transcription Factor CHOP | 2012 |
Mitochondrial uncoupling protein-2 (UCP2) mediates leptin protection against MPP+ toxicity in neuronal cells.
Mitochondrial dysfunction is involved in the pathogenesis of neurodegenerative diseases, including Parkinson's disease (PD). Uncoupling proteins (UCPs) delink ATP production from biofuel oxidation in mitochondria to reduce oxidative stress. UCP2 is expressed in brain, and has neuroprotective effects under various toxic insults. We observed induction of UCP2 expression by leptin in neuronal cultures, and hypothesize that leptin may preserve neuronal survival via UCP2. We showed that leptin preserved cell survival in neuronal SH-SY5Y cells against MPP+ toxicity (widely used in experimental Parkinsonian models) by maintaining ATP levels and mitochondrial membrane potential (MMP); these effects were accompanied by increased UCP2 expression. Leptin had no effect in modulating reactive oxygen species levels. Stable knockdown of UCP2 expression reduced ATP levels, and abolished leptin protection against MPP+-induced mitochondrial depolarization, ATP deficiency, and cell death, indicating that UCP2 is critical in mediating these neuroprotective effects of leptin against MPP+ toxicity. Interestingly, UCP2 knockdown increased UCP4 expression, but not of UCP5. Our findings show that leptin preserves cell survival by maintaining MMP and ATP levels mediated through UCP2 in MPP+-induced toxicity. Topics: 1-Methyl-4-phenylpyridinium; Adenosine Triphosphate; Analysis of Variance; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Cell Survival; Gene Expression Regulation, Neoplastic; Green Fluorescent Proteins; Herbicides; Humans; Ion Channels; Leptin; Membrane Potential, Mitochondrial; Membrane Transport Proteins; MicroRNAs; Mitochondrial Proteins; Mitochondrial Uncoupling Proteins; Neuroblastoma; Neuroprotective Agents; Reactive Oxygen Species; Uncoupling Protein 2 | 2010 |
Identification and characterization of a leptin-responsive neuroblastoma cell line.
The adipocyte-derived hormone leptin plays a critical role in a variety of physiological and pathological actions. As such the determination of leptin signal transduction pathways are important both for understanding the molecular mechanisms of leptin action and for identifying sites for possible therapeutic intervention. Since the hypothalamus is the primary site of leptin action, we sought to identify a neuronal-derived human cell line containing the long form of the leptin receptor (OBRb). To this end, we screened several neuroblastoma cell lines and isolated a sub-line of SH-SY5Y cells, which we designated as SH-OBRb, for further studies. We characterized the transduction pathways induced by leptin in SH-OBRb cells and demonstrated that OBRb mediates tyrosine phosphorylation of STAT3, phosphorylation of ERK1/2, but not SAPK/JNK and p38 MAPK, in a dose and time dependent fashion. In addition, Akt appears to be phosphorylated in the basal state and to be insensitive to further activation by leptin. In summary, we have isolated a unique cell line that can be utilized as a model for use in the study of leptin action and molecular mechanisms. Topics: Cell Line, Tumor; Humans; Leptin; MAP Kinase Kinase 4; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Neuroblastoma; Neurons; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Signal Transduction; STAT3 Transcription Factor; Tyrosine | 2009 |
Excessive nitric oxide attenuates leptin-mediated signal transducer and activator of transcription 3 activation.
The mechanisms of leptin resistance observed in most cases of human obesity are poorly understood. Therefore, we evaluated the effects of nitric oxide (NO) on the leptin-induced activation of Janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) pathways and on the leptin receptor (LEPR) expression using SH-SY5Y cells. Here, we show that the NO donor spermine/NONOate inhibited leptin-induced activation of STAT3 in vitro. The inhibition of leptin-mediated STAT3 phosphorylation caused by excessive NO was partially prevented by a sulfhydryl reducing agent, ascorbic acid. Cellular experiments show that reduced expression of long form leptin receptor (LEPR-b) and STAT3 protein instability induced by NO may be mechanisms of the NO-mediated inhibition of leptin-STAT3 signaling. We also present data showing that the hypothalamic NO content of high-fat (HF)-diet-induced obese mice was higher than that of control mice; this is likely caused by decreased caveolin-1 expression and increased nNOS expression induced by HF diet over 19 weeks. Concurrently with the overproduction of NO, the decrease of hypothalamic LEPR-b in obese mice also supports these in vitro data. Combined results suggest that excess of NO can induce the attenuation of leptin-mediated STAT3 activation through reduced expression of LEPR-b mRNA and instability of STAT3 protein at least in part. Furthermore, our in vivo data indicate that long-term HF diet induces hypothalamic overproduction of NO, which may be related with leptin insensitivity. However, further study is required to warrant direct in vivo evidence of a causal relationship between endogenous excess of hypothalamic NO and central leptin resistance. Topics: Animals; Ascorbic Acid; Caveolin 1; Cell Line, Tumor; Dietary Fats; Down-Regulation; Drug Antagonism; Gene Expression; Humans; Hypothalamus; Leptin; Male; Mice; Mice, Inbred C57BL; Neuroblastoma; Nitrates; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase Type I; Nitrites; Obesity; Phosphorylation; Receptors, Cell Surface; Receptors, Leptin; Spermine; STAT3 Transcription Factor | 2007 |
Role of hypothalamic Foxo1 in the regulation of food intake and energy homeostasis.
Insulin signaling in the hypothalamus plays a role in maintaining body weight. Studies suggest that the forkhead transcription factor Foxo1 is an important mediator of insulin signaling in peripheral tissues. Here we demonstrate that in normal mice, hypothalamic Foxo1 expression is reduced by the anorexigenic hormones insulin and leptin. These hormones' effects on feeding are inhibited when hypothalamic Foxo1 is activated, establishing a new signaling pathway through which insulin and leptin regulate food intake in hypothalamic neurons. Moreover, activation of Foxo1 in the hypothalamus increases food intake and body weight, whereas inhibition of Foxo1 decreases both. Foxo1 stimulates the transcription of the orexigenic neuropeptide Y and Agouti-related protein through the phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway, but suppresses the transcription of anorexigenic proopiomelanocortin by antagonizing the activity of signal transducer-activated transcript-3 (STAT3). Our data suggest that hypothalamic Foxo1 is an important regulator of food intake and energy balance. Topics: Analysis of Variance; Animals; Blotting, Western; Body Weight; Cell Line, Tumor; Chromatin Immunoprecipitation; Eating; Electrophoretic Mobility Shift Assay; Energy Metabolism; Forkhead Box Protein O1; Forkhead Transcription Factors; Gene Expression; Green Fluorescent Proteins; Homeostasis; Humans; Hypothalamus; Immunohistochemistry; Insulin; Leptin; Male; Mice; Mice, Inbred C57BL; Neuroblastoma; RNA, Small Interfering | 2006 |
Antiapoptotic effects of leptin in human neuroblastoma cells.
Many factors regulate nervous system development, including complex cross-talk between local neuroendocrine systems. The adipocyte-secreted hormone leptin, mainly known for its key roles in nutrition and reproductive balance, may also be involved in neuroanatomical organization, myelination processes, and neuronal/glia maturation. SK-N-SH-SY5Y neuroblastoma cells were employed as an in vitro model of human neuronal cells to determine whether leptin exerts neuroprotective activities. We show that SH-SY5Y cells express leptin, the long and short isoforms of the leptin receptor (ObRl, ObRs). In SH-SY5Y cells, leptin induced signal transducer and activator of transcription (STAT)-3 phosphorylation and suppressor of cytokine signaling-3 mRNA expression. Leptin dose-dependently increased cell number (up to 200% at 1 microm by 48 h, P < 0.01), and at 24-48 h, leptin at 100 nm increased SH-SY5Y cell number by 30-50%, respectively. SH-SY5Y cell viability was reduced in serum-free conditions at 24 h, and addition of leptin at 100 nm significantly reduced apoptosis by approximately 20% (P < 0.001). Leptin's antiapoptotic activity required Janus kinase/STAT, MAPK, and phosphatidylinositol-3-kinase activation because the antiapoptotic effects of leptin were abolished, and caspase-3 immunoreactivity increased in the presence of the specific blockers AG490, U0126, or LY294002. Gene array demonstrated that leptin inhibits apoptosis via potent down-regulation of caspase-10 and TNF-related apoptosis-inducing ligand. Our data thus demonstrate, for the first time, that leptin stimulates, in a time- and dose-dependent manner, neuroblastoma cell proliferation and that the underlying mechanisms involve suppression of apoptosis via the Janus kinase-STAT, phosphatidylinositol-3 kinase, and MAPK pathways that culminate altogether in the down-regulation of the apoptotic factors caspase-10 and TNF-related apoptosis-inducing ligand. Topics: Apoptosis; Apoptosis Regulatory Proteins; Blood Proteins; Caspase 10; Caspases; Cell Line, Tumor; DNA-Binding Proteins; Down-Regulation; Humans; In Vitro Techniques; JNK Mitogen-Activated Protein Kinases; Leptin; Membrane Glycoproteins; Mitogen-Activated Protein Kinases; Neuroblastoma; Neurons; Phosphatidylinositol 3-Kinases; Phosphorylation; STAT3 Transcription Factor; TNF-Related Apoptosis-Inducing Ligand; Trans-Activators; Tumor Necrosis Factor-alpha | 2004 |
Modeling the pathways of energy balance using the N1E-115 murine neuroblastoma cell line.
A good in vitro model within which to investigate molecular interactions between feeding relevant neuropeptide systems has been lacking. Consequently, we began using reverse transcriptase-polymerase chain reaction (RT-PCR) to screen various neuronal cell lines for the presence of feeding relevant neuropeptides and receptors. N1E-115 murine neuroblastoma cells have emerged as an attractive candidate for further analysis because they contain mRNA for a variety of key systems implicated in the regulation of energy homeostasis. Topics: Agouti-Related Protein; Animals; Energy Metabolism; Intercellular Signaling Peptides and Proteins; Leptin; Mice; Nerve Tissue Proteins; Neuroblastoma; Neuropeptide Y; Neuropeptides; Pro-Opiomelanocortin; Proteins; Receptor, Insulin; Receptor, Melanocortin, Type 3; Receptor, Melanocortin, Type 4; Receptors, Corticotropin; Repressor Proteins; RNA, Messenger; Suppressor of Cytokine Signaling 3 Protein; Suppressor of Cytokine Signaling Proteins; Transcription Factors; Tumor Cells, Cultured | 2002 |
Differential regulation of leptin receptor expression by insulin and leptin in neuroblastoma cells.
Leptin exerts its effects by interacting with specific membrane receptors (Ob-R). We studied the exact localization of long intracellular domain form (Ob-Rb) in human brain. In addition, we analyzed the regulatory features of Ob-Rb expression in two neuroblastoma cell lines. The Ob-Rb mRNAs were abundant in putamen, frontal lobe, medulla, cerebral cortex, cerebellum, thalamus, hippocampus, corpus callosum, caudate nucleus, and amygdala, indicating that Ob-Rb transcripts are expressed differently from that of other Ob-R isoforms. In SK-N-MC cells, the expression of Ob-Rb mRNA was induced by increasing doses of insulin, and the maximum amount of mRNA expression was 9.4-fold higher in the presence of insulin (100 nM for 24 h), compared to the absence of insulin. In IMR32 cells, the transcripts were increased 4.0-fold when cells were incubated with 1 nM of insulin for 48 h. In contrast, Ob-Rb expression in IMR32 cells decreased to 18% of control following a 24-h incubation period with 50 ng/mL of leptin, compared to incubation in the absence of leptin. These results indicate that expression of Ob-Rb is differentially regulated by inhibitory signals of energy balance in neuroblastoma cells. The identification of the novel regulatory mechanisms involving the Ob-Rb isoform by insulin and leptin now makes it possible to elucidate the underlying mechanisms involving increased food intake and uncontrolled energy balance associated with leptin resistance in obese individuals. Topics: Brain; Carrier Proteins; Eating; Energy Metabolism; Gene Expression Regulation, Neoplastic; Humans; Insulin; Leptin; Neuroblastoma; Receptors, Cell Surface; Receptors, Leptin; RNA, Messenger; Tumor Cells, Cultured | 2000 |
Ciliary neurotrophic factor corrects obesity and diabetes associated with leptin deficiency and resistance.
Receptor subunits for the neurocytokine ciliary neurotrophic factor (CNTF) share sequence similarity with the receptor for leptin, an adipocyte-derived cytokine involved in body weight homeostasis. We report here that CNTF and leptin activate a similar pattern of STAT factors in neuronal cells, and that mRNAs for CNTF receptor subunits, similarly to the mRNA of leptin receptor, are localized in mouse hypothalamic nuclei involved in the regulation of energy balance. Systemic administration of CNTF or leptin led to rapid induction of the tis-11 primary response gene in the arcuate nucleus, suggesting that both cytokines can signal to hypothalamic satiety centers. Consistent with this idea, CNTF treatment of ob/ob mice, which lack functional leptin, was found to reduce the adiposity, hyperphagia, and hyperinsulinemia associated with leptin deficiency. Unlike leptin, CNTF also reduced obesity-related phenotypes in db/db mice, which lack functional leptin receptor, and in mice with diet-induced obesity, which are partially resistant to the actions of leptin. The identification of a cytokine-mediated anti-obesity mechanism that acts independently of the leptin system may help to develop strategies for the treatment of obesity associated with leptin resistance. Topics: Animals; Arcuate Nucleus of Hypothalamus; Blood Glucose; Body Weight; Brain; Carrier Proteins; Cell Line; Ciliary Neurotrophic Factor; Diabetes Mellitus, Type 2; Dietary Fats; DNA-Binding Proteins; Grooming; Humans; Hybrid Cells; Insulin; Leptin; Male; Mice; Mice, Inbred AKR; Mice, Inbred C57BL; Mice, Obese; Motor Activity; Nerve Growth Factors; Nerve Tissue Proteins; Neuroblastoma; Neurons; Obesity; Point Mutation; Proteins; Receptor, Ciliary Neurotrophic Factor; Receptors, Cell Surface; Receptors, Leptin; Receptors, Nerve Growth Factor; Recombinant Proteins | 1997 |