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Kinetics of leptin binding to the Q223R leptin receptor.

ABSTRACT: Studies in human populations and mouse models of disease have linked the common leptin receptor Q223R mutation to obesity, multiple forms of cancer, adverse drug reactions, and susceptibility to enteric and respiratory infections. Contradictory results cast doubt on the phenotypic consequences of this variant. We set out to determine whether the Q223R substitution affects leptin binding kinetics using surface plasmon resonance (SPR), a technique that allows sensitive real-time monitoring of protein-protein interactions. We measured the binding and dissociation rate constants for leptin to the extracellular domain of WT and Q223R murine leptin receptors expressed as Fc-fusion proteins and found that the mutant receptor does not significantly differ in kinetics of leptin binding from the WT leptin receptor. (WT: ka 1.76×106±0.193×106 M-1 s-1, kd 1.21×10-4±0.707×10-4 s-1, KD 6.47×10-11±3.30×10-11 M; Q223R: ka 1.75×106±0.0245×106 M-1 s-1, kd 1.47×10-4±0.0505×10-4 s-1, KD 8.43×10-11±0.407×10-11 M). Our results support earlier findings that differences in affinity and kinetics of leptin binding are unlikely to explain mechanistically the phenotypes that have been linked to this common genetic variant. Future studies will seek to elucidate the mechanism by which this mutation influences susceptibility to metabolic, infectious, and malignant pathologies.

SUBMITTER: Verkerke H

PROVIDER: S-EPMC3990580 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Kinetics of leptin binding to the Q223R leptin receptor.

Verkerke Hans H Naylor Caitlin C Zabeau Lennart L Tavernier Jan J Petri William A WA Marie Chelsea C

PloS one 20140417 4

Studies in human populations and mouse models of disease have linked the common leptin receptor Q223R mutation to obesity, multiple forms of cancer, adverse drug reactions, and susceptibility to enteric and respiratory infections. Contradictory results cast doubt on the phenotypic consequences of this variant. We set out to determine whether the Q223R substitution affects leptin binding kinetics using surface plasmon resonance (SPR), a technique that allows sensitive real-time monitoring of prot ...[more]

PMID: 24743494

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Project description:Leptin is a key hormone of weight regulation that modulates food intake. Since the elaboration of the leptin action mechanism, several studies tried to establish the relationship between obesity and the common polymorphisms of leptin (LEP) and leptin receptor (LEPR) genes, but results were controversial. We studied the association of G2548A of the LEP gene and Q223R of LEPR gene polymorphisms with obesity and metabolic syndrome (MetS). We recruited 169 nonobese volunteers (body mass index [BMI] < 30 kg/m(2)) and 160 obese ones (BMI ≥ 30 kg/m(2)). Glucose, insulin, and lipids were measured. BMI, homeostasis model assessment-insulin resistance (HOMA-IR), and daily energy intake were calculated. After adjustment to confounders parameters, 2548AA was found to increase the MetS (p=0.043) and obesity risk (p=0.019) in the studied population. After stratification according to the degree of obesity, the odds ratio [OR] of 2548AA was associated with moderate obesity (p=0.048) and morbid obesity (p=0.048). The LEPR 223RR genotype was associated with obesity in the studied population (OR=1.74, p=0.037) and only in the overweight (OR=1.8, p=0.049). Subjects with 2548AA had significantly higher BMI, daily energy intake, total cholesterol (TC), waist circumference (WC), insulinemia, and low high-density lipoprotein-cholesterol (HDL-C) levels. With regard to 223RR, we noted a significantly higher daily energy intake, BMI, TC, glycemia, insulinemia, HOMA-IR index, and low HDL-C levels. Haplotype model AR (2548A+223R) and AQ (2548A+223Q) increased the risk of obesity (OR=3.36, p<0.001; OR=2.56, p=0.010, respectively). When we added daily energy intake in adjustment, these significant associations disappeared. In addition, the AR and AQ increased the MetS risk. This significant association persisted after we had added daily energy intake in adjustment. This study showed that LEP G2548A and LEPR Q223R polymorphisms and haplotype combination were associated with MetS and obesity risk in Tunisian volunteers.

Project description:Resistance to amebiasis is associated with a polymorphism in the leptin receptor. Previous studies demonstrated that humans with the ancestral Q223 leptin receptor allele were nearly four times less likely to be infected with Entamoeba histolytica than those carrying the mutant R223 allele. We hypothesized that the Q223 allele protected against E. histolytica via STAT3-mediated transcription of genes required for mucosal immunity. To test this, mice containing the humanized LEPR Q or R allele at codon 223 were intracecally infected with E. histolytica. Susceptibility to amebiasis was assessed, and cecal tissues analyzed for changes in gene expression. By 72 h post-challenge all Q223 mice had cleared E. histolytica, whereas 39% of 223R mice were infected. 37 genes were differentially expressed in response to infection at 72 h, including pro-inflammatory genes (CXCL2, calprotectin (S100A8/9), Pla2g7, Itbg2, and MMP9) and functions pertaining to the movement and activity of immune cells. A comparison at 12 h post-challenge of infected Q223 vs. R223 mice identified a subset of differentially-expressed genes, many of which were closely linked to leptin signaling. Further analyses indicated that the Q223 gene expression pattern was consistent with a suppressed apoptotic response to infection, while 223R showed increased cellular proliferation and recruitment. These studies are the first to illuminate the downstream effects of leptin receptor polymorphisms on intestinal infection by E. histolytica. As such, they are important for the insight that they provide to this previously uncharacterized mechanism of mucosal immunity. Resistance to amebiasis is associated with a polymorphism in the leptin receptor. Previous studies demonstrated that humans with the ancestral Q223 leptin receptor allele were nearly four times less likely to be infected with Entamoeba histolytica than those carrying the mutant R223 allele. We hypothesized that the Q223 allele protected against E. histolytica via STAT3-mediated transcription of genes required for mucosal immunity. To test this, mice containing the humanized LEPR Q or R allele at codon 223 were intracecally infected with E. histolytica. Susceptibility to amebiasis was assessed, and cecal tissues analyzed for changes in gene expression. By 72 h post-challenge all Q223 mice had cleared E. histolytica, whereas 39% of 223R mice were infected. 37 genes were differentially expressed in response to infection at 72 h, including pro-inflammatory genes (CXCL2, calprotectin (S100A8/9), Pla2g7, Itbg2, and MMP9) and functions pertaining to the movement and activity of immune cells. A comparison at 12 h post-challenge of infected Q223 vs. R223 mice identified a subset of differentially-expressed genes, many of which were closely linked to leptin signaling. Further analyses indicated that the Q223 gene expression pattern was consistent with a suppressed apoptotic response to infection, while 223R showed increased cellular proliferation and recruitment. These studies are the first to illuminate the downstream effects of leptin receptor polymorphisms on intestinal infection by E. histolytica. As such, they are important for the insight that they provide to this previously uncharacterized mechanism of mucosal immunity.

Dataset Information

Kinetics of leptin binding to the Q223R leptin receptor.

Publications

Kinetics of leptin binding to the Q223R leptin receptor.

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