Reanalysis of parabiosis of obesity mutants in the age of leptin.
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ABSTRACT:
SUBMITTER: Zeng W
PROVIDER: S-EPMC4517239 | biostudies-other | 2015 Jul
REPOSITORIES: biostudies-other
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Project description:The prevalence of obesity increases with age in humans and in rodents. Age-related obesity is characterized by leptin resistance and associated with heightened risk of metabolic disorders. However, the effect of leptin resistance per se has been difficult to disentangle from other effects of aging. Here we demonstrate that celastrol, a natural phytochemical that was previously shown to act as a leptin sensitizer, induces weight loss in aged animals, but not in young controls. Celastrol reduces food intake and lowers fasting glucose without affecting energy expenditure. Unexpectedly, administration of celastrol just before the dark period disrupted circadian rhythms of sleep and activity. This regimen was also associated with loss of lean mass an outcome that would not be desirable in elderly patients. Adjusting the timing of celastrol administration by 12 hr, to the beginning of the light period, avoided interference with circadian rhythms while retaining the reductions in body weight and adiposity. Thus, targeting leptin signaling is an effective strategy to ameliorate age-associated weight gain, and can profoundly impact circadian rhythms.
| S-EPMC6516176 | biostudies-literature
Project description:Introduction: The ascending prevalence of obesity in recent decades is commonly associated with soaring rates of morbidity and mortality resulting in increased health care costs and decreased quality of life. A systemic state of stress characterized by low grade inflammation and pathologic formation of reactive oxygen species (ROS) usually manifest in obesity. The transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2) is the master regulator of the redox homeostasis and plays a critical role in the resolution of inflammation. Our results indicate that the natural isothiocyanate and potent NRF2 activator sulforaphane reverses the diet-induced obesity in rodents and implicate involvement of leptin receptor singling in this effect. Purpose: Here, we investigate molecular pathways underlying the effects of sulforaphane in reversing diet-induced obesity and interrogate potential pathways that link NRF2 with leptin receptor signaling by conducting whole transcriptome analysis in 6 metabolically active tissues from the diet-induced obese mice that were treated with SFN. Methods: Male 12-week-old C57/BJ wild type mice were fed with high fat diet for 16-20 weeks. Around 28 weeks of age, mice were treated with daily ip injections of either SFN (5 mg/kg) or vehicle for one week. We probed the whole transcriptome in several metabolic tissues including the hypothalamus, liver, brown adipose tissue (BAT), epididymal white adipose tissue (eWAT), inguinal white adipose tissue (iWAT), and skeletal muscle following peripheral SFN administration. Total RNA samples from each tissue were prepared with Trizol. Whole transcriptome were conducted by using Novogene sequencing platform NovaSeq 6000 PE150. The following bioinformatics analysis have been conducted. 1. Data Quality Control: filtering reads containing adapter or with low quality. 2. Statistics Analysis of Data Production and Quality. 3. Mapping Reads to Reference Genome. 4. Gene Expression Quantification. 5. Correlation analysis (For biological replicates only). 6. Differential Expression Analysis (two or more groups of samples). 7. GO Enrichment Analysis of Differentially Expressed Genes (DEGs) (two or more groups of samples). 8. KEGG Pathway Enrichment Analysis of Differentially Expressed Genes (DEGs) (two or more groups of samples). 9. GSEA Enrichment Analysis of Expressed Genes (two or more groups of samples). 10. Protein Protein Interaction Analysis. 11. Reactome Pathway Enrichment Analysis of Differentially Expressed Genes (DEGs) (two or more groups of samples and only for mouse samples). 12. Oncogene Functional Annotation analysis of Differentially Expressed Genes (DEGs) (two or more groups of samples and only for mouse sample). Results: RNAseq results indicated a significant upregulation of the NRF2 target gene HMOX1 only in the skeletal muscle. We also conducted an enrichment analysis to identify potential transcription factors for the significantly upregulated genes. NRF2 was identified as the most significant transcription factor only for the skeletal muscle gene set, providing further support for the skeletal muscle being a primary target tissue of SFN action. We thus conducted a KEGG and GO pathway analysis, and identified ribosome biogenesis, proteasome pathway, and the RNA transport as the significantly upregulated pathways in the SFN-treated muscle samples. In addition to HMOX1, the RNA seq results indicate upregulation of other genes involved in oxidative stress response capacity in SFN treated mice in the skeletal muscle. GCLM (glutamate-cysteine ligase), the first rate-limiting enzyme of glutathione synthesis, SRXN1 (Sulfiredoxin), an oxidoreductase that reduces cysteine-sulfinate, and GSR (glutathione-disulfide reductase), a central antioxidant enzyme, which reduces oxidized glutathione disulfide (GSSG) to the sulfhydryl form glutathione (GSH), and TXNRD1 (thioredoxin reductase 1) which reduces thioredoxins are all upregulated in the skeletal muscle of the SFN-treated DIO animals. Conclusions: Here, we show that the natural isothiocyanate and potent NRF2 activator sulforaphane reverses diet-induced obesity through an NRF2-dependent mechanism that requires a functional leptin receptor signaling and hyperleptinemia. Transcriptional profiling of six major metabolically relevant tissues highlights that sulforaphane suppresses fatty acid synthesis while promoting ribosome biogenesis, reducing ROS accumulation and resolving inflammation, therefore representing a unique transcriptional program that leads to protection from obesity. Our findings argue for clinical evaluation of sulforaphane for weight loss and obesity-associated metabolic disorders.
2022-01-22 | GSE181477 | GEO
Project description:Leptin, a hormone secreted by peripheral adipose tissues, regulates the appetite in animals. Recently, evidence has shown that leptin also plays roles in behavioral response in addition to controlling appetite. In this study, we examined the potential function of leptin on non-appetite behaviors in zebrafish model. By using genome editing tool of Transcription activator-like effector nuclease (TALEN), we successfully knocked out leptin a (lepa) gene by deleting 4 bp within coding region to create a premature-translation stop. Morphological and appetite analysis showed the lepa KO fish display a phenotype with obese, good appetite and elevation of Agouti-related peptide (AgRP) and Ghrelin hormones, consistent with the canonical function of leptin in controlling food intake. By multiple behavior endpoint analyses, including novel tank, mirror biting, predator avoidance, social interaction, shoaling, circadian rhythm, and color preference assay, we found the lepa KO fish display an anxiogenic phenotype showing hyperactivity with rapid swimming, less freezing time, less fear to predator, loose shoaling area forming, and circadian rhythm and color preference dysregulations. Using biochemical assays, melatonin, norepinephrine, acetylcholine and serotonin levels in the brain were found to be significantly reduced in lepa KO fish, while the levels of dopamine, glycine and cortisol in the brain were significantly elevated. In addition, the brain ROS level was elevated, and the anti-oxidative enzyme catalase level was reduced. Taken together, by performing loss-of-function multiple behavior endpoint testing and biochemical analysis, we provide strong evidence for a critical role of lepa gene in modulating anxiety, aggression, fear, and circadian rhythm behaviors in zebrafish for the first time.
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Project description:Aims/hypothesisWhile the class I phosphoinositide 3-kinases (PI3Ks) are well-documented positive regulators of metabolism, the involvement of class II PI3K isoforms (PI3K-C2α, -C2β and -C2γ) in metabolic regulation is just emerging. Organismal inactivation of PI3K-C2β increases insulin signalling and sensitivity, whereas PI3K-C2γ inactivation has a negative metabolic impact. In contrast, the role of PI3K-C2α in organismal metabolism remains unexplored. In this study, we investigated whether kinase inactivation of PI3K-C2α affects glucose metabolism in mice.MethodsWe have generated and characterised a mouse line with a constitutive inactivating knock-in (KI) mutation in the kinase domain of the gene encoding PI3K-C2α (Pik3c2a).ResultsWhile homozygosity for kinase-dead PI3K-C2α was embryonic lethal, heterozygous PI3K-C2α KI mice were viable and fertile, with no significant histopathological findings. However, male heterozygous mice showed early onset leptin resistance, with a defect in leptin signalling in the hypothalamus, correlating with a mild, age-dependent obesity, insulin resistance and glucose intolerance. Insulin signalling was unaffected in insulin target tissues of PI3K-C2α KI mice, in contrast to previous reports in which downregulation of PI3K-C2α in cell lines was shown to dampen insulin signalling. Interestingly, no metabolic phenotypes were detected in female PI3K-C2α KI mice at any age.Conclusions/interpretationOur data uncover a sex-dependent role for PI3K-C2α in the modulation of hypothalamic leptin action and systemic glucose homeostasis.Access to research materialsAll reagents are available upon request.
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Project description:Obesity and colorectal cancer (CRC) are among the leading diseases causing deaths in the world, showing a complex multifactorial pathology. Obesity is considered a risk factor in CRC development through inflammation, metabolic, and signaling processes. Leptin is one of the most important adipokines related to obesity and an important proinflammatory marker, mainly expressed in adipose tissue, with many genetic variation profiles, many related influencing factors, and various functions that have been ascribed but not yet fully understood and elucidated, the most important ones being related to energy metabolism, as well as endocrine and immune systems. Aberrant signaling and genetic variations of leptin are correlated with obesity and CRC, with the genetic causality showing both inherited and acquired events, in addition to lifestyle and environmental risk factors; these might also be related to specific pathogenic pathways at different time points. Moreover, mutation gain is a crucial factor enabling the genetic process of CRC. Currently, the inconsistent and insufficient data related to leptin's relationship with obesity and CRC indicate the necessity of further related studies. This review summarizes the current knowledge on leptin genetics and its potential relationship with the main pathogenic pathways of obesity and CRC, in an attempt to understand the molecular mechanisms of these associations, in the context of inconsistent and contradictory data. The understanding of these mechanisms linking obesity and CRC could help to develop novel therapeutic targets and prevention strategies, resulting in a better prognosis and management of these diseases.
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Project description:Rationale: Maternal obesity is associated with asthma in the offspring. Whether cord blood leptin is associated with risk of asthma in offspring is unclear.Objectives: To assess whether cord blood leptin from women with pregestational obesity predict preschool asthma.Methods: In this birth cohort study, we divided pregnant women into three weight categories during the first obstetric visit: normal (NL), overweight (OW), and obese (OB).Results: We followed the offspring recording atopy, wheezing, and other respiratory illnesses through 30 months of age. Cord blood and peripheral blood at 30 months of age were taken to measure cytokines, adipokines, metabolic biomarkers, and specific immunoglobulin E. Adjusted regression models were used to evaluate the association between maternal obesity and offspring asthma risk, defined by a positive Asthma Predictive Index. Three hundred thirty-nine mothers were recruited; 140 offspring were born from NL, 80 from OW, and 119 from OB mothers. OB women were older and less educated and had higher parity and higher C-section frequency. Offspring from OB women had higher birthweight, head circumference, and placental weight compared with other groups. The proportion of Asthma Predictive Index positive at 30 months of age was 12.2% in the NL, 14.7% in the OW, and 16.8% in the OB group (P = 0.18). Offspring from OB women had higher leptin, leptin/adiponectin ratio, interleukin-10, and insulin than the OW group and higher leptin than the NL group. In the adjusted analysis, offspring from OB mothers with high cord blood leptin had increased risk of asthma (adjusted odds ratio, 1.30; 95% confidence interval, 1.1-1.55; P = 0.003).Conclusions: Offspring from obese mothers with high cord blood leptin have 30% higher asthma risk at age 3.Clinical trial registered with ClinicalTrials.gov (NCT02903134).
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Project description:BACKGROUND:Colorectal cancer (CRC) is the second most commonly diagnosed cancer and the fourth leading cause of cancer-related mortality around the world. OBJECTIVES:With regard to the role of obesity in colorectal cancer (CRC) and the role of leptin in obesity, we investigated whether leptin (LEP) and leptin receptor (LEPR) gene variants are associated with CRC risk. PATIENTS AND METHODS:We evaluated LEP (rs7799039) and LEPR (rs1137101) gene variants by using PCR-RFLP method in 261 cases with CRC and 339 controls. RESULTS:No significant difference was found for rs7799039 and rs1137101gene variants between the cases with CRC and controls. However, the LEPR rs1137101 "GG" genotype compared with "AA" genotype and "AA + AG" genotype was associated with increased risks for obesity, and the differences remained significant after adjustment for confounding factors including age, sex, smoking status, and NSAID use (P = 0.015; OR = 2.42, 95%CI = 1.19 - 4.93 and P = 0.016; OR = 2.28, 95%CI = 1.17 - 4.48, respectively). In addition, the LEPR "G" allele compared with the "A" allele was associated with an increased risk for obesity (P = 0.024; OR = 1.44, 95%CI = 1.05 - 1.98). CONCLUSIONS:Consistent with most previous studies, our findings found no association between LEP (rs7799039) and LEPR (rs1137101) gene variants and CRC risk. However, the LEPR rs1137101 "GG" genotype compared with the "AA" genotype and "AA+AG" genotype was associated with a 2.42-fold and a 2.28-fold increased risk for obesity, respectively.
| S-EPMC5038839 | biostudies-literature
Project description:The revelation of leptin action mechanisms has led to various attempts to establish the association of polymorphisms in the leptin gene with obesity-related phenotypes. But, outcomes have been contradicting, which made the information on the role of the leptin gene in regulating the mechanism of pathophysiology of obesity inexplicable. Moreover, none of the studies are known to have similar implications on the Indian population. To address such contradictions, our study aims to evaluate the association of leptin gene polymorphism with obesity and leptin levels in a South Indian Population. A total of 304 cases (BMI?27.5) and 309 controls (BMI?23) from local inhabitants of Mysore, Karnataka were recruited for the study. The leptin gene variants rs7799039, rs2167270 and rs4731426 independently, as well as in 4 haplotype combinations, were found to be significantly associated with the risk of obesity. An increasing trend in BMI and leptin levels was observed with every addition of A and C minor alleles of exonic variant (rs2167270) and intronic variant (rs4731426) respectively. However, only AA genotype of SNP rs7799039 was positively associated with BMI. None of the SNPs were associated with fat percentage and waist to hip ratio. On a whole, this data suggests that the common polymorphisms in the leptin gene are strong predictors of obesity and leptin levels in South Indians.
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Project description:This investigation examines whether a low intermittent dose of rapamycin will avoid the hyperlipidemia and diabetes-like syndrome associated with rapamycin while still decreasing body weight and adiposity in aged obese rats. Furthermore, we examined if the rapamycin-mediated decrease in serum leptin was a reflection of decreased adiposity, diminished leptin synthesis, or both. To these ends, rapamycin (1mg/kg) was administered three times a week to 3 and 24-month old rats. Body weight, food intake, body composition, mTORC1 signaling, markers of metabolism, as well as serum leptin levels and leptin synthesis in adipose tissue were examined and compared to that following a central infusion of rapamycin. Our data suggest that the dosing schedule of rapamycin acts on peripheral targets to inhibit mTORC1 signaling, preferentially reducing adiposity and sparing lean mass in an aged model of obesity resulting in favorable outcomes on blood triglycerides, increasing lean/fat ratio, and normalizing elevated serum leptin with age. The initial mechanism underlying the rapamycin responses appears to have a peripheral action and not central. The peripheral rapamycin responses may communicate an excessive nutrients signal to the hypothalamus that triggers an anorexic response to reduce food consumption. This coupled with potential peripheral mechanism serves to decrease adiposity and synthesis of leptin.
| S-EPMC4906318 | biostudies-literature
Project description:BACKGROUND AND PURPOSE: Protection against ischaemia-reperfusion (I/R) injury involves PI3K-Akt and p44/42 MAPK activation. Leptin which regulates appetite and energy balance also promotes myocyte proliferation via PI3K-Akt and p44/42 MAPK activation. We, therefore, hypothesized that leptin may also exhibit cardioprotective activity. EXPERIMENTAL APPROACH: The influence of leptin on I/R injury was examined in perfused hearts from C57Bl/6 J mice that underwent 35 min global ischaemia and 35 min reperfusion, infarct size being assessed by triphenyltetrazolium chloride staining. The concomitant activation of cell-signalling pathways was investigated by Western blotting. The effect of leptin on mitochondrial permeability transition pore (MPTP) opening was studied in rat cardiomyocytes. KEY RESULTS: Leptin (10 nM) administered during reperfusion reduced infarct size significantly. Protection was blocked by either LY294002 or UO126, inhibitors of Akt and p44/42 MAPK, respectively. Western blotting confirmed that leptin stimulated p44/42 MAPK phosphorylation significantly. Akt phosphorylation was also enhanced but did not achieve statistical significance. Additionally, leptin treatment was associated with a significant increase in p38 phosphorylation. By contrast, leptin caused downregulation of phosphorylated and non-phosphorylated STAT3, and of total AMP-activated kinase. Cardiomyocytes responded to leptin with delayed opening of the MPTP and delayed time until contracture. CONCLUSIONS AND IMPLICATIONS: Our data indicate for the first time that the adipocytokine, leptin, has direct cardioprotective properties which may involve the PI3-Akt and p44/42 MAPK pathways.
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