Nitric Oxide Synthase 1 Adaptor Protein Research Articles

Oxidative Stress Induced Ventricular Arrhythmia and Impairment of Cardiac Function in <i>Nos1ap</i> Deleted Mice

Genome-wide association study has identified that the genetic variations at NOS1AP (neuronal nitric oxide synthase-1 adaptor protein) were associated with QT interval and sudden cardiac death (SCD). However, the mechanism linking a genetic variant of NOS1AP and SCD is poorly understood. We used Nos1ap knockout mice (Nos1ap(-/-)) to determine the involvement of Nos1ap in SCD, paying special attention to oxidative stress.At baseline, a surface electrocardiogram (ECG) and ultrasound echocardiography (UCG) showed no difference between Nos1ap(-/-) and wild-type (WT) mice. Oxidative stress was induced by a single injection of doxorubicin (Dox, 25 mg/kg). After Dox injection, Nos1ap(-/-) showed significantly higher mortality than WT (93.3 versus 16.0% at day 14, P < 0.01). ECG showed significantly longer QTc in Nos1ap(-/-) than WT, and UCG revealed significant reduction of fractional shortening (%FS) only in Nos1ap(-/-) after Dox injection. Spontaneous ventricular tachyarrhythmias were documented by telemetry recording after Dox injection only in Nos1ap(-/-). Ex vivo optical mapping revealed that the action potential duration (APD)90 was prolonged at baseline in Nos1ap(-/-), and administration of Dox lengthened APD90 more in Nos1ap(-/-) than in WT. The expression of Bnp and the H2O2 level were higher in Nos1ap(-/-) after Dox injection. Nos1ap(-/-) showed a reduced amplitude of calcium transient in isolated cardiomyocytes after Dox injection. Administration of the antioxidant N-acetyl-L-cysteine significantly reduced mortality of Nos1ap(-/-) by Dox injection, accompanied by prevention of QT prolongation and a reduction in %FS.Although Nos1ap(-/-) mice have apparently normal hearts, oxidative stress evokes ventricular tachyarrhythmia and heart failure, which may cause sudden cardiac death.

Increase of Heart Rate and QTc by Amitriptyline, But Not by Venlafaxine, Is Correlated to Serum Concentration

Electrocardiographic pathologies are a common problem during antidepressant treatment. The authors investigated the association of serum concentrations of antidepressants and heart rate, QT, and QTc. Polymorphisms of NOS1AP (nitric oxide synthase 1 adaptor protein) rs10494366 and rs12143842 as potential influence factors also were considered. In the amitriptyline sample (n = 59), significant Spearman ρ correlations were found between serum concentration and QTc (r = 0.333, P = 0.010), as well as heart rate (r = 0.407, P = 0.001). Patients with a serum concentration greater than the therapeutic range (>200 ng/mL) exhibit significantly higher heart rates (87.0 ± 13.3 vs 80.0 ± 13.9, U test P = 0.011) and higher QTc values (443.8 ± 28.8 vs 427.9 ± 20.6, U test P = 0.022). Excluding the 26 patients with a serum concentration greater than the therapeutic range, patients with rs12143842 risk alleles exhibit higher heart rates and as a trend lower QT intervals with no difference in QTc. In the venlafaxine sample (n = 81), no significant association between serum concentration and heart rate, QT, or QTc was revealed. In summary, the risk for relevant electrocardiographic alterations induced by tricyclic antidepressants, such as amitriptyline, is dependent on serum concentrations. NOS1AP polymorphisms may be a genetic vulnerability factor.

NOS1AP Functionally Associates with YAP To Regulate Hippo Signaling.

Deregulation of cellular polarity proteins and their associated complexes leads to changes in cell migration and proliferation. The nitric oxide synthase 1 adaptor protein (NOS1AP) associates with the tumor suppressor protein Scribble to control cell migration and oncogenic transformation. However, how NOS1AP is linked to the cell signaling events that curb oncogenic progression has remained elusive. Here we identify several novel NOS1AP isoforms, NOS1APd, NOS1APe, and NOS1APf, with distinct cellular localizations. We show that isoforms with a membrane-interacting phosphotyrosine binding (PTB) domain can associate with Scribble and recognize acidic phospholipids. In a screen to identify novel binding proteins, we have discovered a complex consisting of NOS1AP and the transcriptional coactivator YAP linking NOS1AP to the Hippo signaling pathway. Silencing of NOS1AP reduces the phosphorylation of YAP and of the upstream kinase Lats1. Conversely, expression of NOS1AP promotes YAP and Lats1 phosphorylation, which correlates with reduced TEAD activity and restricted cell proliferation. Together, these data implicate a role for NOS1AP in the regulation of core Hippo signaling and are consistent with the idea that NOS1AP functions as a tumor suppressor.

Angiotensin II Upregulates CAPON Expression via ERK‐MAPK‐CREB Pathway in the Paraventricular Nucleus of Rats with Chronic Heart Failure

Elevated levels of angiotensin II (Ang II) and its receptor (AT1) in brain are responsible for increase sympatho‐excitation during heart failure (HF).Previously, we have demonstrated that higher levels of CAPON (nitric oxide synthase 1‐adaptor protein) down regulate neuronal nitric oxide synthase (nNOS) in the paraventricular nucleus (PVN) of rats with HF. The significant increase in CAPON transcript (15 folds) in the PVN of HF rats was ameliorated by Losartan treatment (10 mg/kg/day for three weeks), suggesting the involvement of AngII/AT1R signaling in transcriptional up‐regulation of CAPON. In vitro studies using NG108 cells showed that Ang II dependent increases in CAPON expression was abrogated in presence of the mitogen‐activated protein kinase/ERK kinase 1/2 inhibitor U0126. The in silico analysis of the ~7.5 kb upstream DNA sequences from the translational start site of CAPON genes identified two likely promoter elements (Promoter 2.0 Prediction Server) containing the sequences responsive (TES Software) to transcriptional factor CREB binding. Concurrently, there was activation of ERK and CREB transcriptional factors in the PVN of rats with HF as evident by increased ERK‐P/ERK (1.43±0.1 Sham. vs. 1.98±0.1 HF) and CREB‐P/CREB (1.07±0.03 Sham. vs. 1.56±0.05 HF) ratios. The siRNA‐mediated silencing of ERK and CREB in NG108 cells ameliorate Ang II mediated upregulation of CAPON further supporting the involvement of MAP kinase in facilitating CAPON up‐regulation. Taken together, our results demonstrate the involvement of the ERK1/2 pathway in selective up‐regulation of CAPON expression, possibly via activation of CREB.

Nitric Oxide Synthase 1 Adaptor Protein, a Protein Implicated in Schizophrenia, Controls Radial Migration of Cortical Neurons

BackgroundWhere a neuron is positioned in the brain during development determines neuronal circuitry and information processing needed for normal brain function. When aberrations in this process occur, cognitive disorders may result. Patients diagnosed with schizophrenia have been reported to show altered neuronal connectivity and heterotopias. To elucidate pathways by which this process occurs and become aberrant, we have chosen to study the long isoform of nitric oxide synthase 1 adaptor protein (NOS1AP), a protein encoded by a susceptibility gene for schizophrenia. MethodsTo determine whether NOS1AP plays a role in cortical patterning, we knocked down or co-overexpressed NOS1AP and a green fluorescent protein or red fluorescent protein (TagRFP) reporter in neuronal progenitor cells of the embryonic rat neocortex using in utero electroporation. We analyzed sections of cortex (ventricular zone, intermediate zone, and cortical plate [CP]) containing green fluorescent protein or red fluorescent protein TagRFP positive cells and counted the percentage of positive cells that migrated to each region from at least three rats for each condition. ResultsNOS1AP overexpression disrupts neuronal migration, resulting in increased cells in intermediate zone and less cells in CP, and decreases dendritogenesis. Knockdown results in increased migration, with more cells reaching the CP. The phosphotyrosine binding region, but not the PDZ-binding motif, is necessary for NOS1AP function. Amino acids 181 to 307, which are sufficient for NOS1AP-mediated decreases in dendrite number, have no effect on migration. ConclusionsOur studies show for the first time a critical role for the schizophrenia-associated gene NOS1AP in cortical patterning, which may contribute to underlying pathophysiology seen in schizophrenia.

NOS1AP Modulates Intracellular Ca2+ in Cardiac Myocytes and is Up-Regulated in Dystrophic Cardiomyopathy

NOS1AP gene (nitric oxide synthase 1-adaptor protein) is strongly associated with abnormalities in the QT interval of the electrocardiogram and with sudden cardiac death. To determine the role of NOS1AP in the physiology of the cardiac myocyte, we assessed the impact of silencing NOS1AP, using siRNA, on [Ca(2+)]i transients in neonatal cardiomyocytes. In addition, we examined the co-localization of NOS1AP with cardiac ion channels, and finally, evaluated the expression of NOS1AP in a mouse model of dystrophic cardiomyopathy. Using siRNA, NOS1AP levels were reduced to ~30% of the control levels (p<0.05). NOS1AP silencing in cardiac myocytes reduced significantly the amplitude of electrically evoked calcium transients (p<0.05) and the degree of S-nitrosylation of the cells (p<0.05). Using confocal microscopy, we evaluated NOS1AP subcellular location and interactions with other proteins by co-localization analysis. NOS1AP showed a high degree of co-localization with the L-type calcium channel and the inwardly rectifying potassium channel Kir3.1, a low degree of co-localization with the ryanodine receptor (RyR2) and alfa-sarcomeric actin and no co-localization with connexin 43, suggesting functionally relevant interactions with the ion channels that regulate the action potential duration. Finally, using immunofluorescence and Western blotting, we observed that in mice with dystrophic cardiomyopathy, NOS1AP was significantly up-regulated (p<0.05). These results suggest for a role of NOS1AP on cardiac arrhythmias, acting on the L-type calcium channel, and potassium channels, probably through S-nitrosylation.

Searching for Sudden Death SNPs in Calcium Handling Genes

Cardiac arrhythmias are a major clinical problem and lead to more than 250 000 sudden cardiac deaths (SCDs) each year in the United States alone.[1][1] Our ability to predict those at risk for sudden death remains poor. The majority of patients who die suddenly are not identified as being at high

Selectively silencing Nitric Oxide Synthase 1 Adaptor Protein in the Nucleus Tractus Solitarius leads to QT Interval Prolongation via Glutamate‐mediated neurotoxicity

Variants of the nitric oxide synthase 1 adaptor protein (NOS1AP) locus are strongly related to QT interval prolongation and sudden cardiac death (SCD) in human. Our aim was to study the action of NOS1AP in the NTS by knockdown of NOS1AP using lentiviral vector‐mediated shRNA (Lv‐NOS1AP‐shRNA). qPCR data showed NOS1AP mRNA levels were expressed in NTS 3‐fold higher than organs such as kidney and heart in SD rats. Microinjection of Lv‐NOS1AP‐shRNA in NTS caused significant reduction in NOS1AP expression in SD rats. NOS1AP knockdown in NTS did not alter blood pressure (BP), heart rate (HR) recorded by radiotelemetry. ECG analysis revealed heart rate variability (HRV) was significantly reduced (SDNN, 51.2±5.6 vs 5.0±1.3 ms, P&lt; .001) and QTc interval was markedly prolonged (72.4±4 vs 105±11 ms, P&lt; .05) in NOS1AP knockdown rats. To study the cellular mechanism underlying NOS1AP action, we studied the effect of NOS1AP knockdown on glutamate‐induced neurotoxicity in Cath‐a cells. Treatment of cells with Lv‐NOS1AP‐shRNA significantly reduced NOS1AP expression, and was associated with increased glutamate‐induced neurotoxicity, suggesting a protective effect of NOS1AP. In summary, all results indicate that NOS1AP dysfunction in NTS might play an important role in the pathogenesis of cardiac arrhythmia which, in part, could be due to increased sensitivity to glutamate induced neurotoxicity.Research Support: NDSU‐COBRE

NOS1AP is associated with increased severity of PTSD and depression in untreated combat veterans

BackgroundPosttraumatic stress disorder (PTSD) and depressive disorder are over represented in combat veterans. Veterans with both disorders have an increased risk of suicide. The nitric oxide synthase 1 adaptor protein (NOS1AP) gene, which modulates stress-evoked N-methyl-d-aspartate (NMDA) activity, was investigated in combat veterans. MethodsA comprehensive genetic analysis of NOS1AP and its association with PTSD was investigated in Vietnam combat veterans with PTSD (n=121) and a group of healthy control individuals (n=237). PTSD patients were assessed for symptom severity and level of depression using the Mississippi Scale for Combat-Related PTSD and the Beck Depression Inventory-II (BDI). ResultsThe G allele of NOS1AP SNP rs386231 was significantly associated with PTSD (p=0.002). Analysis of variance revealed significant differences in BDI-II and Mississippi scores between genotypes for rs386231 with the GG genotype associated with increased severity of depression (p=0.002 F=6.839) and higher Mississippi Scale for Combat-Related PTSD scores (p=0.033). Haplotype analysis revealed that the C/G haplotype (rs451275/rs386231) was significantly associated with PTSD (p=0.001). LimitationsThe sample sizes in our study were not sufficient to detect SNP associations with very small effects. In addition the study was limited by its cross sectional design. ConclusionsThis is the first study reporting that a variant of the NOS1AP gene is associated with PTSD. Our data also suggest that a genetic variant in NOS1AP may increase the susceptibility to severe depression in patients with PTSD and increased risk for suicide.

Asociación de esquizofrenia y sus dimensiones clínicas con el gen NOS1AP en población colombiana

IntroductionThe nitric oxide synthase 1 adaptor protein (NOS1AP) gene is possibly implicated in schizophrenia etiopathogenesis. ObjectiveTo determine the association of NOS1AP gene variants with schizophrenia and the relationship of variants with the clinical dimensions of the disorder in the Colombian population. MethodologyIt is a case-control study with 255 subjects per group. Markers within the NOS1AP gene were typified as well as other informative material of genetic origin so as to adjust by population stratification. A factorial analysis of the main components for each item in the Scales for Evaluating Negative Symptoms (SENS) together with the Scales for Evaluating Positive Symptoms (SEPS) to determine clinical dimensions. ResultsAssociation between the C/C genotype of the rs945713 marker with schizophrenia (OR = 1.79, 95% CI: 1.13 – 2.84) was found. The C/C genotype of the rs945713 was related to higher scores in the “affective flattening and alogia” dimension; and the A/A genotype of the rs4657181 marker was associated to lower scores in the same dimension. ConclusionsSignificant associations of markers inside the NOS1AP gene with schizophrenia and the “affective flattening and alogia” clinical dimension were found. These results are consistent with previous studies and support the possibility that NOS1AP influences schizophrenia susceptibility. Furthermore, NOS1AP might be a modifier of schizophrenia clinical characteristics.

Association of rs10918594 Polymorphisms of Nitric Oxide Synthase 1 Adaptor Protein (NOS1AP) with QTc Interval Prolongation During Kidney Transplantation

Background The mechanisms of sudden cardiac death are difficult to recognize, but repolarization disturbances have been shown to be the cause. The purpose of this study was to investigate whether the polymorphism of nitric oxide synthase 1 adaptor protein (NOS1AP) was related to the risk of occurrence of corrected QTc-interval prolongation and ventricular arrhythmias recorded on electrocardiography (ECG) Holter monitoring in kidney transplant recipients. Study Design The 75 adult first kidney transplant patients included 43 men with an overall mean age of 45 ± 12 years (range, 20–68). Additional patient monitoring during the procedure and in the postoperative period consisted of a continuous ECG tracing recording and investigation of the rs10918594 NOS1AP polymorphism. Results We observed Transient QTc-interval prolongation during the perioperative period. NOS1AP genotypes were in Hardy-Weinberg equilibrium. For further statistical analysis, we combined GG homozygotes and CG heterozygotes because of the small numbers available; therefore, only a dominant mode of inheritance was investigated. There were no gender differences in QTc-interval patterns. Analysis of variance with repeated measures revealed no interaction between NOS1AP and QTc-interval values taken at various times among the kidney recipients. Conclusions The transplantation procedure may lead to dynamic repolarization disturbances, which may produce an increased risk of severe arrhythmias despite optimization of patient status. The NOS1AP rs203462 polymorphisms did not correlate with an increased risk of QT interval prolongation among kidney recipients.

Association of the rs10918594 of Nitric Oxide Synthase 1 Adaptor Protein (NOS1AP) polymorphisms with the graft function after kidney transplantation

The purpose of this study was to investigate the relationship of nitric oxide synthase 1 adaptor protein (NOS1AP) polymorphism with serum creatinine level and occurrence of delayed graft function (DGF) in kidney transplant recipients. This prospective observational study included 75 kidney transplantations. The data from 40 kidney donors (8 females, 32 males) included sex, age, and cause of death. Donors fully met multi-organ transplantation criteria. Recipient data included sex, age, cause of renal insufficiency, and time and number of hemodialyses prior to transplantation. Applying polymerase chain reaction restriction fragments length polymorphism method, we investigated rs10918594 NOS1AP polymorphism among the 75 kidney recipients. The function of every transplanted kidney was correlated with this polymorphism. We defined DGF as requirement for at least 1 hemodialysis after kidney transplantation. We investigated the association of NOS1AP polymorphism with the recipient serum creatinine levels at day 1 and 180 days after kidney transplantation and the occurrence of DGF. The analysis of variance showed higher serum creatinine levels in kidney recipients with GG genotype compared with the CC_CG genotype at day 1 and at day 180 post-transplantation. Occurrence of DGF in the post-operative period in kidney recipients with the variant genotypes CG compared with the GG_CC genotype was higher, although these differences were no statistically significant. Our data suggests no statistically significant association of the rs10918594 polymorphism of nitric oxide synthase 1 adaptor protein (NOS1AP) with the graft function after kidney transplantation.

A common variant of NOS1AP is associated with QT interval duration in a Chinese population with Type 2 diabetes

Electrocardiographic ventricular repolarization QT parameters are independent risk factors for cardiovascular events and sudden cardiac death in diabetic patients. The aim of the study was to investigate the association of polymorphisms of the nitric oxide synthase 1 adaptor protein (NOS1AP) gene with QT interval in Chinese subjects with or without Type 2 diabetes. Three single nucleotide polymorphisms (SNPs) (rs10494366, rs12143842 and rs12029454) were genotyped in 1240 Type 2 diabetic patients (631 men and 609 women) and 1196 normal controls (433 men and 763 women). Individuals with overt diseases other than diabetes were excluded. Heart-rate corrected QT interval (QTc) was determined by standard 12-lead ECG and Bazett formula. Sex-pooled analysis and sex-specific analysis for genotype-phenotype association were both conducted. In the diabetic group, the rs12143842 T allele was associated with a 3.87-ms (P = 0.014, empirical P = 0.039) increase in QTc duration for each additional allele copy, while rs10494366 and rs12029454 exhibited no significant association with QTc. We found no evidence of association for the three SNPs in subjects with normal glucose regulation. No significant SNP-gender and -diabetes affection interaction was observed. The genetic variant rs12143842 in NOS1AP is associated with QT interval duration in a Chinese population with Type 2 diabetes. Future studies in different populations are needed to validate this finding and to evaluate the impact of NOS1AP variants on cardiovascular events and sudden cardiac death in diabetic patients.

Relationship of common candidate gene variants to electrocardiographic T-wave peak to T-wave end interval and T-wave morphology parameters

Single-nucleotide polymorphisms (SNPs) in genes encoding cardiac ion channels and nitric oxide synthase-1 adaptor protein (NOS1AP) are associated with electrocardiographic (ECG) QT-interval duration, but the association of these SNPs with new, prognostically important ECG measures of ventricular repolarization is unknown. The purpose of this study was to examine the relationship of SNPs to ECG T-wave peak to T-wave end (TPE) interval and T-wave morphology parameters. We studied 5,890 adults attending the Health 2000 Study, a Finnish epidemiologic survey. TPE interval and four T-wave morphology parameters were measured from digital 12-lead ECGs and related to the seven SNPs showing a phenotypic effect on QT-interval duration in the Health 2000 Study population. In multivariable analyses, the KCNH2 K897T minor allele was associated with a 1.2-ms TPE-interval shortening (P = .00005) and the KCNH2 intronic rs3807375 minor allele was associated with a 0.8-ms TPE-interval prolongation (P = .001), whereas the KCNE1 D85N variant had no TPE-interval effect (P = .20). NOS1AP minor alleles (rs2880058, rs4657139, rs10918594, rs10494366) were associated with a shorter TPE interval (effects from 0.5 to 0.8 ms, P from .032 to .002), which resulted from their stronger effects on QT(peak) than QT(end) interval. None of the SNPs showed a consistent association with T-wave morphology parameters. KCNH2 K897T and rs3807375 as well as the four studied NOS1AP variants have modest effects on ECG TPE interval but are not related to T-wave morphology measures. The previously observed prognostic value of T-wave morphology parameters likely is not based on these SNPs.

NOS1AP variant associated with incidence of type 2 diabetes in calcium channel blocker users in the Atherosclerosis Risk in Communities (ARIC) study

To validate the reported association between rs10494366 in NOS1AP (the gene encoding nitric oxide synthase-1 adaptor protein) and the incidence of type 2 diabetes in calcium channel blocker (CCB) users and to identify additional NOS1AP variants associated with type 2 diabetes risk. Data from 9 years of follow-up in 9,221 middle-aged white and 2,724 African-American adults free of diabetes at baseline from the Atherosclerosis Risk in Communities study were analysed. Nineteen NOS1AP variants were examined for associations with incident diabetes and fasting glucose levels stratified by baseline CCB use. Prevalence of CCB use at baseline was 2.7% (n = 247) in whites and 2.3% (n = 72) in African-Americans. Among white CCB users, the G allele of rs10494366 was associated with lower diabetes incidence (HR 0.57, 95% CI 0.35-0.92, p = 0.016). The association was marginally significant after adjusting for age, sex, obesity, smoking, alcohol use, physical activity, hypertension, heart rate and electrocardiographic QT interval (HR 0.63, 95% CI 0.38-1.04, p = 0.052). rs10494366 was associated with lower average fasting glucose during follow-up (p = 0.037). No other variants were associated with diabetes risk in CCB users after multiple-testing correction. No associations were observed between any NOS1AP variant and diabetes development in non-CCB users. NOS1AP variants were not associated with diabetes risk in either African-American CCB users or non-CCB users. We have independently replicated the association between rs10494366 in NOS1AP and incident diabetes among white CCB users. Further exploration of NOS1AP variants and type 2 diabetes and functional studies of NOS1AP in type 2 diabetes pathology is warranted.

Cardiac nitric oxide synthase-1 localization within the cardiomyocyte is accompanied by the adaptor protein, CAPON

The mechanism(s) regulating nitric oxide synthase-1 (NOS1) localization within the cardiac myocyte in health and disease remains unknown. Here we tested the hypothesis that the PDZ-binding domain interaction between CAPON (carboxy-terminal PDZ ligand of NOS1), a NOS1 adaptor protein and NOS1, contribute to NOS1 localization in specific organelles within cardiomyocytes. Ventricular cardiomyocytes and whole heart homogenates were isolated from sham and post-myocardial infarction (MI) wild-type (C57BL/6) and NOS1 −/− female mice for quantification of CAPON protein expression levels. NOS1, CAPON, xanthine oxidoreductase and Dexras1, a CAPON binding partner, were all present and enriched in isolated cardiac sarcoplasmic reticulum (SR) fractions. CAPON co-immunoprecipitated with the mu and alpha isoforms of NOS1 in whole heart lysates, and co-localization of CAPON and NOS1 was demonstrated in the SR and mitochondria with dual immuno-gold electron microscopy. Following MI, CAPON and NOS1 both redistributed to caveolae and colocalized with caveolin-3. In addition, following MI, expression level of CAPON remained unchanged and Dexras1 was reduced, CAPON binding to xanthine oxidoreductase was augmented and the plasma membrane calcium ATPase (PMCA) increased. In NOS1 deficient myocytes, CAPON abundance in the SR was reduced, and redistribution to caveolae and PMCA binding after MI was absent. Together these findings support the hypothesis that NOS1 redistribution in injured myocardium requires the formation of a complex with the PDZ adaptor protein CAPON.

Genetic Variations in Nitric Oxide Synthase 1 Adaptor Protein Are Associated With Sudden Cardiac Death in US White Community-Based Populations

The ECG QT interval is associated with risk of sudden cardiac death (SCD). A previous genome-wide association study demonstrated that allelic variants (rs10494366 and rs4657139) in the nitric oxide synthase 1 adaptor protein (NOS1AP), which encodes a carboxy-terminal PDZ ligand of neuronal nitric oxide synthase, are associated with the QT interval in white adults. The present analysis was conducted to validate the association between NOS1AP variants and the QT interval and to examine the association with SCD in a combined population of 19 295 black and white adults from the Atherosclerosis Risk In Communities Study and the Cardiovascular Health Study. We examined 19 tagging single-nucleotide polymorphisms in the genomic blocks containing rs10494366 and rs4657139 in NOS1AP. SCD was defined as a sudden pulseless condition of cardiac origin in a previously stable individual. General linear models and Cox proportional hazards regression models were used. Multiple single-nucleotide polymorphisms in NOS1AP, including rs10494366, rs4657139, and rs16847548, were significantly associated with adjusted QT interval in whites (P<0.0001). In whites, after adjustment for age, sex, and study, the relative hazard of SCD associated with each C allele at rs16847548 was 1.31 (95% confidence interval 1.10 to 1.56, P=0.002), assuming an additive model. In addition, a downstream neighboring single-nucleotide polymorphism, rs12567209, which was not correlated with rs16847548 or QT interval, was also independently associated with SCD in whites (relative hazard 0.57, 95% confidence interval 0.39 to 0.83, P=0.003). Adjustment for QT interval and coronary heart disease risk factors attenuated but did not eliminate the association between rs16847548 and SCD, and such adjustment had no effect on the association between rs12567209 and SCD. No significant associations between tagging single-nucleotide polymorphisms in NOS1AP and either QT interval or SCD were observed in blacks. In a combined analysis of 2 population-based prospective cohort studies, sequence variations in NOS1AP were associated with baseline QT interval and the risk of SCD in white US adults.

Identification of a common variant at the NOS1AP locus strongly associated to QT-interval duration

QT-interval prolongation is an electrophysiologic phenomenon associated with sudden cardiac death. The QT-interval in the general population is approximately 35% heritable. In genome-wide association studies, a common variant (rs10494366T > G) within the nitric oxide synthase 1 adaptor protein (NOS1AP) gene was identified and consistently associated with QT-interval duration. Yet, the causal variant remains unclear. Therefore, we performed fine mapping of the association of the NOS1AP locus with QT-interval within the Rotterdam Study, a population-based, prospective cohort study of individuals of > or =55 years of age. First, we tested the association of single-nucleotide polymorphisms (SNPs) in or within +/-100 kb of the NOS1AP gene with QT-interval duration, using sex-specific unstandardized residuals after regression on age and RR-interval, in 385 individuals using the combined set of SNPs present in the Affymetrix 500k and Illumina 550k chip arrays. Subsequently, we examined correspondence of the association signals in 4606 individuals using the Illumina 550k array. A C-to-T SNP at chromosome 1 position 160300514 (rs12143842, T-allele frequency = 24%) was associated with a QT-interval duration increase of 4.4 ms per additional T-allele (P = 4.4 x 10(-28)). For comparison, the most strongly associated variant to date, rs10494366T > G, was associated with a 3.5 ms increase (P = 1.6 x 10(-23)) per additional G-allele. None of the inferred haplotypes showed a stronger effect than the individual rs12143842C > T SNP. In conclusion, we found rs12143842 6 kb upstream distance of NOS1AP to be more strongly associated to QT-interval duration than rs10494366T > G. Functional analysis of this marker is warranted.

Common variation in the NOS1AP gene is associated with reduced glucose-lowering effect and with increased mortality in users of sulfonylurea

The single nucleotide polymorphism rs10494366 in the nitric oxide synthase 1 adaptor protein (NOS1AP) gene is associated with QTc prolongation, through an effect on the intracellular Ca levels. As sulfonylurea stimulate insulin secretion by an increased influx of Ca, we hypothesized that this polymorphism is associated with the glucose-lowering effect and mortality risk in sulfonylurea users. Associations between the NOS1AP polymorphism, prescribed doses, and mortality rates in sulfonylurea, metformin, and insulin users were assessed in the Rotterdam Study, a population-based cohort study of 7983 elderly people. We identified 619 participants who were prescribed oral antidiabetic drugs during follow-up. In glibenclamide users carrying the TG genotype, the prescribed doses were higher compared with the glibenclamide users carrying the TT genotype [0.38 defined daily dose units, 95% confidence interval (CI) 0.14-0.63]. Glibenclamide users with the TG or GG genotype had an increased mortality risk compared with glibenclamide users with the TT genotype [hazard ratio (HR) 2.80, 95% CI: 1.09-7.22]. Tolbutamide users with the TG or GG genotype (HR: 0.30, 95% CI: 0.14-0.63) and glimepiride users with the TG or GG genotype (HR: 0.18, 95% CI: 0.04-0.74) had a decreased mortality risk compared with tolbutamide and glimepiride users with the TT genotype. In participants with the TG or GG genotype at rs10494366 in the NOS1AP gene, glibenclamide is less effective in reducing glucose levels and mortality rates were higher compared with glibenclamide users with the TT genotype. In tolbutamide and glimepiride users, the TG and GG genotype were associated with a reduced mortality rate.

Association of NOS1AP genetic variants with QT interval duration in families from the Diabetes Heart Study.

Prolongation of the electrocardiographic QT interval is a risk factor for sudden cardiac death (SCD). Diabetic individuals are at increased risk for prolonged QT interval and SCD. We sought to replicate the finding that genetic variants in the nitric oxide synthase 1 adaptor protein (NOS1AP) gene are associated with QT interval duration in a type 2 diabetes-enriched sample of European ancestry. Two single nucleotide polymorphisms (SNPs) in NOS1AP were genotyped in 624 European Americans and 127 African Americans from 400 pedigrees enriched for type 2 diabetes. An additive genetic model was tested for each SNP in ancestry-specific analyses in the total sample and the diabetic subset (European Americans, n = 514; African Americans, n = 115), excluding from the analyses individuals taking QT-altering medications. In European Americans, rs10494366 minor homozygotes had a 9.3-ms-longer QT interval compared with major homozygotes (P = 5.7 x 10(-5)); rs10918594 minor homozygotes had a 12.5-ms-longer QT interval compared with major homozygotes (P = 1.5 x 10(-6)). Restricting analyses to the diabetic European Americans strengthened the effect despite the reduction in sample size (11.3-ms difference, P = 5.1 x 10(-5); 13.9-ms difference, P = 1.6 x 10(-6), respectively). No association between the NOS1AP SNPs and QT interval duration was observed in the limited number of African Americans. Two NOS1AP SNPs are strongly associated with QT interval duration in a predominately diabetic European-American sample. Stronger effects of NOS1AP variants in diabetic individuals suggest that this patient subset may be particularly susceptible to genetic variants that influence myocardial depolarization and repolarization as manifest in the QT interval.