Paraoxonase single nucleotide variants show associations with polycystic ovary syndrome: a meta-analysis.
ABSTRACT: BACKGROUND:Etiology of polycystic ovary syndrome (PCOS) is attributed to genetic and environmental factors. One environmental factor is oxidative stress. Paraoxonase 1 (PON1) is an antioxidant high-density lipoprotein-associated enzyme encoded by the PON1 gene. The PON1 gene has been implicated in the risk for PCOS, the influence of which appears to come from single nucleotide variants (SNVs) at multiple genetic loci. However, association study reports have been inconsistent which compels a meta-analysis to obtain more precise estimates. METHODS:From 12 publications, extracted genotype data were used in two genetic procedures. First, linkage disequilibrium (LD) was used to group eight PON SNVs into three: LD1, LD2 and LD3. Second, frequencies of the variant (var), wild-type (wt) and heterozygous (het) genotypes were used for genetic modeling (allele-genotype for LD1 and standard for LD2 and LD3). Risk associations were expressed in terms of pooled odds ratios (ORs), 95% confidence intervals (CIs) and Pa-values. Evidence was considered strong when significance was high (Pa?
Project description:<h4>Background</h4>Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is overexpressed or activated in several advanced-stage solid cancers. It is known to play both kinase-dependent and -independent roles in promoting tumor progression and metastasis. Numerous inhibitors, targeting either the enzymatic or scaffolding activities of FAK have been generated, with varying degree of success. Here, we describe a novel approach to site-specifically target both kinase-dependent and -independent FAK functions at focal adhesions (FAs), the primary sites at which the kinase exerts its activity.<h4>Methods</h4>We took advantage of the well-characterized interactions between the paxillin LD motifs and the FAK FAT domain and generated a polypeptide (LD2-LD3-LD4) expected to compete with interactions with paxillin. Co-immunoprecipitation experiments were performed to examine the interaction between the LD2-LD3-LD4 polypeptide and FAK. The effects of LD2-LD3-LD4 in the localization and functions of FAK, as well as FA composition, were evaluated using quantitative immunofluorescence, cell fractionation, FA isolation and Western Blot analysis. Live cell imaging, as well as 2-D migration and cell invasion assays were used to examine the effects on FA turnover and tumor cell migration and invasion.<h4>Results</h4>Expression of the LD2-LD3-LD4 polypeptide prevents FAK localization at FAs, in a controlled and dose-dependent manner, by competing with endogenous paxillin for FAK binding. Importantly, the LD2-LD3-LD4 peptide did not otherwise affect FA composition or integrin activation. LD2-LD3-LD4 inhibited FAK-dependent downstream integrin signaling and, unlike existing inhibitors, also blocked FAK's scaffolding functions. We further show that LD2-LD3-LD4 expression markedly reduces FA turnover and inhibits tumor cell migration and invasion. Finally, we show that dimers of a single motif, linked through a flexible linker of the proper size, are sufficient for the displacement of FAK from FAs and for inhibition of tumor cell migration. This work raises the possibility of using a synthetic peptide as an antimetastatic agent, given that effective displacement of FAK from FAs only requires dimers of a single LD motif linked by a short flexible linker.<h4>Conclusion</h4>In conclusion, these results suggest that FAK displacement from FAs is a promising new strategy to target critical processes implicated in cancer progression and metastasis. Video abstract.
Project description:Previous studies have shown association of single nucleotide polymorphisms (SNPs) in 3 contiguous genes (PON1, PON2, and PON3) encoding paraoxonase with risk of Alzheimer disease (AD). We evaluated the association of serum paraoxonase activity measured by phenyl acetate (PA) and thiobutyl butyrolactone (TBBL) with risk of AD and with 26 SNPs spanning the PON gene cluster in 266 AD cases and 306 sibling controls from the MIRAGE study. The odds of AD (adjusted for age, gender, and ethnicity) increased 20% for each standard deviation decrease in PA or TBBL activity. There were association signals with activity in all 3 genes. Haplotypes including SNPs spanning the PON genes were generally more significant than haplotypes comprising SNPs from 1 gene. Significant interactions were observed between SNP pairs located across the PON cluster with either serum activity measure as the outcome, and between several PON SNPs and PA activity with AD status as the outcome. Our results suggest that low serum paraoxonase activity is a risk factor for AD. Furthermore, multiple variants in PON influence serum paraoxonase activity and their effects may be synergistic.
Project description:<h4>Objective</h4>To assess the linear measurements of edentulous ridges recorded from multidetector row computed tomography (MDCT) images obtained by a previously untested ultra-low dose in combination with filtered back-projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR).<h4>Methods</h4>Three cadavers were imaged using a reference protocol with a standard dose and FBP (volume CT dose index (CTDIvol): 29.4 mGy) and two ultra-low-dose protocols, LD1 and LD2 (CTDIvol: 0.53 and 0.29 mGy). All test examinations were reconstructed with FBP, ASIR 50, ASIR 100, and MBIR. Linear measurements from the images of the edentulous ridges recorded from the test protocols were compared with those from the reference using a one-sample t test, Bland-Altman plots, and linear regression. Statistical significance was set at a p value of 0.05.<h4>Results</h4>The one-sample t test demonstrated a statistically significant difference between the measurements from the reference protocol and all test protocols. The difference was not clinically significant for the following three test protocols: LD1/FBP, LD1/ASIR 50, and LD2/FBP. Bland-Altman plots with linear regression showed no systematic variation between the measurements obtained with the reference protocol and these three test protocols.<h4>Conclusions</h4>The lowest-dose protocol to demonstrate comparable measurements with a standard MDCT dose was CTDIvol 0.29 mGy with FBP. These results must be considered with caution for areas of the jaws with thin cortication. The results in areas of thin cortication should be verified by studies with larger sample sizes at such areas and comparison with true gold standard measurements.
Project description:Paraoxonases (PON) are a family of proteins (PON1, 2 and 3) with multiple enzymatic activities. PON1 interferes with homoserine lactone-mediated quorum sensing in bacteria and with reactive oxygen species (ROS) in humans and mice. PON1 gene mutations have been linked to multiple traits, including aging, and diseases of the cardiovascular, nervous and gastrointestinal system. The overlapping enzymatic activities in the PON family members and high linkage disequilibrium rates within their polymorphisms confound animal and human studies of PON1 function. In contrast, arthropods such as Drosophila melanogaster have no PON homologs, resulting in an ideal model to study interactions between PON genotype and host phenotypes. We hypothesized that expression of PON1 in D. melanogaster would alter ROS. We found that PON1 alters expression of multiple oxidative stress genes and decreases superoxide anion levels in normal and germ-free D. melanogaster. We also found differences in the composition of the gut microbiota, with a remarkable increase in levels of Lactobacillus plantarum and associated changes in expression of antimicrobial and cuticle-related genes. PON1 expression directly decreased superoxide anion levels and altered bacterial colonization of the gut and its gene expression profile, highlighting the complex nature of the interaction between host genotype and gut microbiota. We speculate that the interaction between some genotypes and human diseases may be mediated by the presence of certain gut bacteria that can induce specific immune responses in the gut and other host tissues.
Project description:Mammary gland dysplasia and postpartum hypogalactia often occur in humans and in the livestock breeding industry. However, their underlying mechanisms are not clear yet. Mifepristone, which has a high affinity for progesterone (P4) and glucocorticoid receptors, was exploited here to induce the disorders of mammary gland development and lactation. Four strategies were devised for treating pregnant mice with mifepristone. In the first strategy, mice were administered 1.20 mg mifepristone/kg body weight (BW) on pregnancy day 4 (Pd4). In the second strategy, mifepristone was administered to mice twice, with 1.20 mg/kg BW on Pd4 and 0.40 mg/kg BW on Pd8. In the third strategy, mice were treated with a single dose of 0.40 mg mifepristone/kg BW on Pd8. In the fourth strategy, mice were administered 0.40 mg mifepristone/kg BW on Pd8 and 0.20 mg mifepristone/kg BW on Pd12. The results suggested that mifepristone administration at the dose of 1.20 mg/kg BW on Pd4 caused significant reduction in milk production on lactation day 1 (Ld1), Ld2, and Ld3, as assessed using a weigh-suckle-weigh assay. Mammary ?-casein expression, milk yields, litter growth rates, gland structure, and serum concentrations of 17-? estrogen (E2), P4, prolactin (PRL), growth hormone (GH), corticosterone (CORT) and oxytocin (OT) as well as the receptors of these hormones were determined during pregnancy or lactation after performing the first (Pd4) strategy. The results demonstrated that mifepristone administration during early pregnancy decreased ?-casein expression, milk yields and litter growth rates, induced fewer alveoli, enlarged alveolar lumina, and altered the levels of E2, P4, PRL, GH, CORT, and OT as well as the mRNA expression of these hormonal receptors during pregnancy or early lactation. The present study on pregnant mice treated with mifepristone offers an innovative murine model to study the mechanism underlying mammary gland dysplasia and postpartum hypogalactia.
Project description:Paraoxonase (PON) constitutes a family of calcium-dependent mammalian enzymes comprising of PON1, PON2, and PON3. PON family shares ~60% sequence homology. These enzymes exhibit multiple activities like paraoxonase, arylesterase, and lactonase in a substrate dependent manner. Decreased PON activity has been reported in diseases like cardiovascular disease, atherosclerosis, and diabetes. Even though, PON2 is the oldest member of the family, PON1 is the only member studied in silico. In this study, the structure of PON2 was modeled using MODELLER 9v7 and its interactions with relevant ligands and it's physiological substrate homocysteine thiolactone was performed using AutoDock 4.0. The results reveal that PON1 and PON2 share common ligand binding patterns for arylesterase and lactonase activity, whereas in case of paraoxon binding, the residues involved in the interactions were different. Interestingly, the substrate HCTL was found to have the lowest free energy of binding (?G) and highest affinity for PON2 than PON1.
Project description:Low serum paraoxonase (PON) activity is associated with the risk of coronary artery disease, diabetes and systemic lupus erythematosus (SLE). Our prior studies have shown that the PON1/rs662 (p.Gln192Arg), PON1/rs854560 (p.Leu55Met), PON3/rs17884563 and PON3/rs740264 SNPs (single nucleotide polymorphisms) significantly affect serum PON activity. Since PON1, PON2 and PON3 share high degree of structural and functional properties, in this study, we examined the role of PON2 genetic variation on serum PON activity, risk of SLE and SLE-related clinical manifestations in a Caucasian case-control sample.PON2 SNPs were selected from HapMap and SeattleSNPs databases by including at least one tagSNP from each bin defined in these resources. A total of nineteen PON2 SNPs were successfully genotyped in 411 SLE cases and 511 healthy controls using pyrosequencing, restriction fragment length polymorphism (RFLP) or TaqMan allelic discrimination methods.Our pair-wise linkage disequilibrium (LD) analysis, using an r² cutoff of 0.7, identified 14 PON2 tagSNPs that captured all 19 PON2 variants in our sample, 12 of which were not in high LD with known PON1 and PON3 SNP modifiers of PON activity. Stepwise regression analysis of PON activity, including the known modifiers, identified five PON2 SNPs [rs6954345 (p.Ser311Cys), rs13306702, rs987539, rs11982486, and rs4729189; P = 0.005 to 2.1 × 10??] that were significantly associated with PON activity. We found no association of PON2 SNPs with SLE risk but modest associations were observed with lupus nephritis (rs11981433, rs17876205, rs17876183) and immunologic disorder (rs11981433) in SLE patients (P = 0.013 to 0.042).Our data indicate that PON2 genetic variants significantly affect variation in serum PON activity and have modest effects on risk of lupus nephritis and SLE-related immunologic disorder.
Project description:Objectives:Oxidative stress, induced by physical activity, may stimulate the expression, release, and activity of certain antioxidant enzymes. We investigated the effect of three repeated bouts of strenuous exercise on paraoxonase 1 concentration (PON1c) and paraoxonase activity (PON). Methods:Eleven average-trained healthy men (age 34.0 ± 5.2 years) performed three strenuous exercise tests on a treadmill separated by 72 hours periods of resting. PON1c, PON, ferric-reducing activity of plasma (FRAP), lipid profile, C-reactive protein concentration (CRP), and lactate concentration were determined in plasma. Results:Each exercise bout resulted in similar PON1c, PON, FRAP, and high-density lipoprotein concentration (HDL-C) increments, while PON/HDL-C ratio remained stable in all repetitions. Percentage increments at the bout of each exercise were higher for PON1c (by 64.82% at the first, by 92.9% at the second, and by 77.02% at the third exercise) than for PON (by 6.49% at the first, 10.06% at the second, and by 12.32% at the third exercise). Association was found between preexercise PON and PON1c (r = 0.56, p = 0.029), pre- (r = 0.87, p = 0.00003) and postexercise HDL-C (r = 0.6, p = 0.0002), preexercise PON and cardiovascular fitness level of participants measured as VO2max (r = 0.39, p = 0.026), and postexercise PON and lactate concentration (r = 0.44, p = 0.01). Conclusions:PON1c and PON increase during strenuous exercise, yet the effect of exercise on PON1 concentration is more pronounced. PON1 does not show tolerance to physical activity. The enzyme may provide short-term protection from oxidative stress in each exercise bout. PON may depend on exercise load. Cardiovascular fitness levels may be associated with PON1 activity.
Project description:In humans and rodents, paraoxonase (PON/Pon) 1 expression and activity in livers and serum are higher in females than in males, and some drugs increase paraoxonase's expression. However, the underlining mechanisms of gender-divergent expression and chemical regulation of Pon1 remain largely unknown. The present study determined the regulatory mechanisms contributing to gender-divergent and chemically altered Pon expression in mouse livers. Pon1 mRNA was much more abundant in the livers of mice than other tissues, with higher levels in female livers than male livers at mRNA and protein levels. Pon2 mRNA was ubiquitously expressed in mouse tissues, but minimally in mouse liver. Pon3 mRNA was most abundant in mouse lung and liver and less abundant in other tissues. Pon1 mRNA was lowest in fetal liver, markedly increased at parturition, and remained relatively constant thereafter. Pon2 and Pon3 mRNA are highly expressed in fetal liver and decreased after birth. Male-pattern growth hormone (GH) administration in hypophysectomized and lit/lit mice decreased Pon1 expression. Sex hormones and female-pattern GH administration had no effect on Pon1 expression, indicating the importance of male-pattern GH in regulating Pon1. Aryl hydrocarbon receptor, pregnane X receptor, and NF-E2-related factor activators had no effect on Pon1 mRNA. A constitutive androstane receptor (CAR) activator decreased Pon1 expression in wild-type but not CAR-null mice. In conclusion, Pon1 mRNA was most abundant in adult mouse livers, whereas Pon2 and Pon3 mRNAs were most abundant in fetal mouse livers. Female-predominant Pon1 expression in mouse livers is caused by the inhibitory effects of male-pattern GH secretion, and CAR activation decreases Pon1 expression.
Project description:Atorvastatin ?-lactone, a major, pharmacologically inactive metabolite, has been associated with toxicity. In a previous study we showed that polymorphisms of UGT1A3 influence atorvastatin ?-lactone formation. Here we investigated the reverse reaction, atorvastatin ?-lactone hydrolysis, in a human liver bank. Screening of microarray data revealed paraoxonases PON1 and PON3 among 17 candidate esterases. Microsomal ?-lactone hydrolysis was significantly correlated to PON1 and PON3 protein (r(s)?=?0.60; r(s)?=?0.62, respectively; P?<?0.0001). PON1 and PON3 were strongly correlated to each other (r(s)?=?0.60) but PON1 was shown to be more extensively glycosylated than PON3. In addition a novel splice-variant of PON3 was identified. Genotyping of 40 polymorphisms within the PON-locus identified PON1 promoter polymorphisms (-108T?>?C, -832G?>?A, -1741G?>?A) and a tightly linked group of PON3 polymorphisms (-4984A?>?G, -4105G?>?A, -1091A?>?G, -746C?>?T, and F21F) to be associated with changes in atorvastatin ?-lactone hydrolysis and expression of PON1 but not PON3. However, carriers of the common PON1 polymorphisms L55M or Q192R showed no difference in ?-lactone hydrolysis or PON expression. Haplotype analysis revealed decreased ?-lactone hydrolysis in carriers of the most common haplotype *1 compared to carriers of haplotypes *2, *3, *4, and *7. Analysis of non-genetic factors showed association of hepatocellular and cholangiocellular carcinoma with decreased PON1 and PON3 expression, respectively. Increased C-reactive protein and ?-glutamyl transferase levels were associated with decreased protein expression of both enzymes, and increased bilirubin levels, cholestasis, and presurgical exposure to omeprazole or pantoprazole were related to decreased PON3 protein. In conclusion, PON-locus polymorphisms affect PON1 expression whereas non-genetic factors have an effect on PON1 and PON3 expression. This may influence response to therapy or adverse events in statin treatment.