Morphological alterations of brain structure are generally assumed to be involved in the pathophysiology of obsessive–compulsive disorder (OCD). Yet, little is known about the morphological connectivity properties of structural brain networks in OCD or about the heritability of those morphological connectivity properties. To better understand these properties, we conducted a study that defined three different groups: OCD group with 30 subjects, siblings group with 19 subjects, and matched controls group with 30 subjects. A structural brain network was constructed using 68 cortical regions of each subject within their respective group (i.e., one brain network for each group). Both small-worldness and modularity were measured to reflect the morphological connectivity properties of each constructed structural brain network. When compared to the matched controls, the structural brain networks of patients with OCD indeed exhibited atypical small-worldness and modularity. Specifically, small-worldness showed decreased local efficiency, and modularity showed reduced intra-connectivity in Module III (default mode network) and increased interconnectivity between Module I (executive function) and Module II (cognitive control/spatial). Intriguingly, the structured brain networks of the unaffected siblings showed similar small-worldness and modularity as OCD patients. Based on the atypical structural brain networks observed in OCD patients and their unaffected siblings, abnormal small-worldness and modularity may indicate a candidate endophenotype for OCD.
Obsessive–compulsive disorder; Cortical thickness; Brain networks; Modularity; Small-worldness
Currently available third- or later-line therapy for metastatic colorectal cancer (mCRC) is limited in its efficacy, with a weak survival benefit in patients who progressed after two or more lines of standard therapy. Our retrospective study aimed to explore the value of bevacizumab plus chemotherapy in this setting.
Patients with mCRC who received fluoropyrimidine, oxaliplatin, and irinotecan as first- and second-line chemotherapy were selected for inclusion. Treatment consisted of bevacizumab plus chemotherapy. Chemotherapy consisted mainly of oxaliplatin, irinotecan, and fluoropyrimidine.
Between February 2010 and December 2012, 35 consecutive patients with mCRC were treated with bevacizumab plus chemotherapy as a third- or later-line treatment. No complete responses, seven partial responses (20%), 22 stable disease responses (62.9%), and six progressive disease responses (17.1%) were obtained, producing an objective response rate of 20% and a disease control rate of 82.9%. With a median follow-up of 11.3 months (range: 0.7–48.0 months), the median progression-free survival was 5.98 months (95% confidence interval: 4.76–7.2 months), and the median overall survival was 14.77 months (95% confidence interval: 11.45–18.1 months). In the univariate analysis, patients with a primary colon tumor might have had a longer overall survival than patients with a primary rectal tumor (18.8 months vs 11.1 months, respectively; P=0.037). Common chemotherapy-related toxicities were nausea/vomiting (48.6%), fatigue (34.3%), leucopenia (40%), neutropenia, (42.9%), and anemia (42.9%), with one patient with grade 3 neutropenia, and two patients with grade 3 thrombocytopenia. The common bevacizumab-associated toxicity was hypertension (31.4%). None of the patients discontinued therapy or died because of bevacizumab-associated toxicities.
Our data showed that adding bevacizumab to third- or later-line therapy might lead to tumor control and improved survival in heavily pretreated mCRC patients. In addition, preliminary data suggested that primary colon cancer was more likely to benefit from bevacizumab-containing regimens. Toxicities were acceptable, and no new toxicity was identified. Further studies are needed to validate these findings.
bevacizumab; chemotherapy; metastatic colorectal cancer
D-dimer, a fibrin degradation product, is related to risk of cardiovascular disease and venous thromboembolism. Genetic determinants of D-dimer are not well characterized; notably, few data have been reported for African American (AA), Asian, and Hispanic populations.
Materials and Methods
We conducted a large-scale candidate gene association study to identify variants in genes associated with D-dimer levels in multi-ethnic populations. Four cohorts, comprising 6,848 European Americans (EAs), 2,192 AAs, 670 Asians, and 1,286 Hispanics in the NHLBI Candidate Gene Association Resource (CARe) consortium, were assembled. Approximately 50,000 genotyped SNPs in 2,000 cardiovascular disease gene loci were analyzed by linear regression, adjusting for age, sex, study site, and principal components in each cohort and ethnic group. Results across studies were combined within each ethnic group by meta-analysis.
Twelve SNPs in coagulation factor V (F5) and 3 SNPs in the fibrinogen alpha chain (FGA) were significantly associated with D-dimer level in EAs with p < 2.0×10−6. The signal for the most associated SNP in F5 (rs6025, F5 Leiden) was replicated in Hispanics (p = 0.023), while that for the top functional SNP in FGA (rs6050) was replicated in AAs (p = 0.006). No additional SNPs were significantly associated with D-dimer.
Our study replicated previously reported associations of D-dimer with SNPs in F5 (F5-Leiden) and FGA in EAs; we demonstrated replication of the association of D-dimer with FGA rs6050 in AAs and the F5-Leiden variant in Hispanics.
D-dimer; genetic association study; CARe consortium; single nucleotide polymorphisms
Cell-permeable orthosteric ligands can assist folding of G protein–coupled receptors in the endoplasmic reticulum (ER); this pharmacochaperoning translates into increased cell surface levels of receptors. Here we used a folding-defective mutant of human A1-adenosine receptor as a sensor to explore whether endogenously produced adenosine can exert a chaperoning effect. This A1-receptor-Y288 A was retained in the ER of stably transfected human embryonic kidney 293 cells but rapidly reached the plasma membrane in cells incubated with an A1 antagonist. This was phenocopied by raising intracellular adenosine levels with a combination of inhibitors of adenosine kinase, adenosine deaminase, and the equilibrative nucleoside transporter: mature receptors with complex glycosylation accumulated at the cell surface and bound to an A1-selective antagonist with an affinity indistinguishable from the wild-type A1 receptor. The effect of the inhibitor combination was specific, because it did not result in enhanced surface levels of two folding-defective human V2-vasopressin receptor mutants, which were susceptible to pharmacochaperoning by their cognate antagonist. Raising cellular adenosine levels by subjecting cells to hypoxia (5% O2) reproduced chaperoning by the inhibitor combination and enhanced surface expression of A1-receptor-Y288 A within 1 hour. These findings were recapitulated for the wild-type A1 receptor. Taken together, our observations document that endogenously formed adenosine can chaperone its cognate A1 receptor. This results in a positive feedback loop that has implications for the retaliatory metabolite concept of adenosine action: if chaperoning by intracellular adenosine results in elevated cell surface levels of A1 receptors, these cells will be more susceptible to extracellular adenosine and thus more likely to cope with metabolic distress.
Tissue plasminogen activator (tPA), a serine protease, catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for endogenous fibrinolysis. In some populations, elevated plasma levels of tPA have been associated with myocardial infarction and other cardiovascular diseases (CVD). We conducted a meta-analysis of genome-wide association studies (GWAS) to identify novel correlates of circulating levels of tPA.
Approach and Results
Fourteen cohort studies with tPA measures (N=26,929) contributed to the meta-analysis. Three loci were significantly associated with circulating tPA levels (P <5.0×10−8). The first locus is on 6q24.3, with the lead SNP (rs9399599, P=2.9×10−14) within STXBP5. The second locus is on 8p11.21. The lead SNP (rs3136739, P=1.3×10−9) is intronic to POLB and less than 200kb away from the tPA encoding gene PLAT. We identified a non-synonymous SNP (rs2020921) in modest LD with rs3136739 (r2 = 0.50) within exon 5 of PLAT (P=2.0×10−8). The third locus is on 12q24.33, with the lead SNP (rs7301826, P=1.0×10−9) within intron 7 of STX2. We further found evidence for association of lead SNPs in STXBP5 and STX2 with expression levels of the respective transcripts. In in vitro cell studies, silencing STXBP5 decreased release of tPA from vascular endothelial cells, while silencing of STX2 increased tPA release. Through an in-silico lookup, we found no associations of the three lead SNPs with coronary artery disease or stroke.
We identified three loci associated with circulating tPA levels, the PLAT region, STXBP5 and STX2. Our functional studies implicate a novel role for STXBP5 and STX2 in regulating tPA release.
tissue plasminogen activator; genome-wide association study; meta-analysis; cardiovascular disease risk; fibrinolysis; hemostasis
Biochemical response to ursodeoxycholic acid (UDCA) in patients with primary biliary cirrhosis (PBC) is variable. We have previously reported that augmented expression of lysosome-associated membrane protein 2 (LAMP-2) was correlated with the severity of PBC. This study aimed to determine whether serum LAMP-2 could serve as a predictor of biochemical response to UDCA. The efficiency of serum LAMP-2 to predict biochemical response was assessed after 1 year of UDCA treatment in PBC patients by a retrospective analysis. We found that the basal serum LAMP-2 level was increased in PBC, especially in patients with stage III-IV (p = 0.010) or TBIL > 1 mg/dL (p = 0.014). Baseline serum LAMP-2 was higher in non-responders than that in responders, but the difference was statistically insignificant. However, after UDCA treatment, serum LAMP-2 level decreased prominently in the first 3 months, which was more obvious in responders. Further studies showed that the 35% decline of LAMP-2 after treatment for 3 months could be stated as an indicator of UDCA response with the sensitivity of 62.9% and specificity of 75.0% by Paris criteria. Meanwhile the specificity and sensitivity were identified as 63.5% and 64.1% by Barcelona criteria. Together, a decline in LAMP-2 might help to predict the response to UDCA.
Myocardial tissue injury caused by ischemia and hypoxia is a major cause of fatal diseases, including coronary atherosclerosis resulting from myocardial infarction and stroke. Trimetazidine (TMZ), as an anti-ischemic and antioxidant agent, has been demonstrated to preventing ischemia/reperfusion-induced cardiomyocyte apoptosis. However, the anti-apoptosis mechanism of TMZ has not been fully elucidated. The present study demonstrated that miR-21 involved trimetazidine-induced anti-apoptosis during H/R injury in H9C2 cell. In this study, TMZ increased miR-21 expression which further upregulated the Akt signaling activity via suppressing the expression of phosphatase and tensin homolog (PTEN) in H/R H9C2 cell. The increased activity of Akt signaling decreased the ratio of Bax/Bcl-2 and the expression of caspase-3 and inhibited H/R induced apoptosis. In conclusion, this study revealed the mechanism that TMZ up-regulated miR-21 expression, then miR-21 targeted PTEN increasing the PI3K pathway and finally the activation of this pathway counteracted the apoptotic effect of hypoxia/reperfusion.
Trimetazidine; H/R injury; miR-21; PTEN/Akt pathway
Brain‐derived neurotrophic factor (BDNF) is a pleiotropic peptide involved in maintaining
endothelial integrity. It is unknown if circulating BDNF levels are associated with risk of
cardiovascular disease (CVD).
Methods and Results
We prospectively investigated the association of circulating BDNF levels with cardiovascular
events and mortality in 3687 participants (mean age 65 years, 2068 women) from the Framingham Heart
Study (FHS). Using a common nonsynonomous single nucleotide polymorphism (SNP) in the
BDNF gene (rs6265), we then performed a Mendelian randomization experiment in the
CARDIoGRAM (Coronary ARtery DIsease Genome‐Wide Replication And Meta‐Analysis)
consortium (>22 000 coronary artery disease [CAD] cases, >60 000 controls) to
investigate whether SNP rs6265 was associated with CAD in CARDIoGRAM and, if so, whether the effect
estimate differed from that predicted based on FHS data. On follow‐up (median 8.9 years), 467
individuals (261 women) in FHS experienced a CVD event, and 835 (430 women) died. In
multivariable‐adjusted Cox regression, serum BDNF was associated inversely with CVD risk
(hazard ratio [HR] per 1‐SD increase 0.88, 95% CI 0.80 to 0.97,
P=0.01) and with mortality (HR 0.87, 95% CI 0.80 to 0.93,
P=0.0002). SNP rs6265 was associated with BDNF concentrations (0.772
ng/mL increase per minor allele copy) in FHS. In CARDIoGRAM, SNP rs6265 was associated with
CAD (odds ratio 0.957, 95% CI 0.923 to 0.992), a magnitude consistent with the predicted
effect (HR per minor allele copy 0.99, 95% CI 0.98 to 1.0; P=0.06 for
difference between predicted and observed effect).
Higher serum BDNF is associated with a decreased risk of CVD and mortality. Mendelian
randomization suggests a causal protective role of BDNF in the pathogenesis of CVD.
cardiovascular disease; growth factors; Mendelian randomization; mortality; risk factors
Carriers of the T allele of the single-nucleotide polymorphism rs13038305 tend to have lower cystatin C levels and higher cystatin C-based estimated glomerular filtration rate (eGFRcys). Adjusting for this genetic effect on cystatin C concentrations may improve GFR estimation, reclassify cases of CKD, and strengthen risk estimates for cardiovascular disease (CVD) and mortality.
Setting & Population
Four population-based cohorts: Atherosclerosis Risk in Communities (ARIC), Cardiovascular Health (CHS), Framingham Heart (FHS), and Health, Aging, and Body Compostion (Health ABC) studies.
We estimated the association of rs13038305 with eGFRcys and eGFRcr, and performed longitudinal analyses of the associations of eGFRcys with mortality and cardiovascular events following adjustment for rs13038305.
We assessed reclassification by genotype-adjusted eGFRcys across CKD categories: <45, 45–59, 60–89, and ≥90 mL/min/1.73 m2. We compared mortality and CVD outcomes in those reclassified to a worse eGFRcys category with those unaffected. Results were combined using fixed-effect inverse-variance meta-analysis.
In 14,645 participants, each copy of the T allele of rs13038305 (frequency, 21%), was associated with 6.4% lower cystatin C concentration, 5.5 mL/min/1.73 m2 higher eGFRcys, and 36% [95% CI, 29%–41%] lower odds of CKD. Associations with CVD (HR, 1.17; 95% CI, 1.14–1.20) and mortality (HR, 1.22; 95% CI, 1.19–1.24) per 10- ml/min/1.73 m2 lower eGFRcys were similar with or without rs13038305 adjustment. In total, 1134 participants (7.7%) were reclassified to a worse CKD category following rs13038305 adjustment, and rates of CVD and mortality were higher in individuals who were reclassified. However, the overall net reclassification index was not significant for either outcome, at 0.009 (95% CI, −0.003 to 0.022) for mortality and 0.014 (95% CI, 0.0 to 0.028) for CVD.
rs13038305 only explains a small proportion of cystatin C variation.
Statistical adjustment can correct a genetic bias in GFR estimates based on cystatin C in carriers of the T allele of rs13038305 and result in changes in disease classification. However, on a population level, the effects on overall reclassification of CKD status are modest.
Cystatin C; chronic kidney disease; genetics; single nucleotide polymorphism; net reclassification improvement
Transposable elements (TEs, transposons) are mobile genetic DNA sequences. TEs can insert copies of themselves into new genomic locations and they have the capacity to multiply. Therefore, TEs have been crucial in the shaping of hosts’ current genomes. TEs can be utilized as genetic markers to study population genetic diversity. The rice stem borer Chilo suppressalis Walker is one of the most important insect pests of many subtropical and tropical paddy fields. This insect occurs in all the rice-growing areas in China. This research was carried out in order to find diversity between C. suppressalis field populations and detect the original settlement of C. suppressalis populations based on the piggyBac-like element (PLE). We also aim to provide insights into the evolution of PLEs in C. suppressalis and the phylogeography of C. suppressalis.
Here we identify a new piggyBac-like element (PLE) in the rice stem borer Chilo suppressalis Walker, which is called CsuPLE1.1 (GenBank accession no. JX294476). CsuPLE1.1 is transcriptionally active. Additionally, the CsuPLE1.1 sequence varied slightly between field populations, with polymorphic indels (insertion/deletion) and hyper-variable regions including the identification of the 3′ region outside the open reading frame (ORF). CsuPLE1.1 insertion frequency varied between field populations. Sequences variation was found between CsuPLE1 copies and varied within and among field populations. Twenty-one different insertion sites for CsuPLE1 copies were identified with at least two insertion loci found in all populations.
Our results indicate that the initial invasion of CsuPLE1 into C. suppressalis occurred before C. suppressalis populations spread throughout China, and suggest that C. suppressalis populations have a common ancestor in China. Additionally, the lower reaches of the Yangtze River are probably the original settlement of C. suppressalis in China. Finally, the CsuPLE1 insertion site appears to be a candidate marker for phylogenetic research of C. suppressalis.
Electronic supplementary material
The online version of this article (doi:10.1186/s12867-014-0028-y) contains supplementary material, which is available to authorized users.
Transposon; piggyBac; Molecular characterization; Evolution; Chilo suppressalis
Chronic administration of D-galactose (D-gal) is a useful method for establishing a model of natural aging in the auditory system. Previous studies have demonstrated that NADPH oxidases (NOXs) may be an important source of reactive oxygen species (ROS) in the peripheral auditory system (PAS) and cause an increase in mitochondrial DNA (mtDNA) common deletion (CD) levels in the PAS and central auditory system (CAS) of rats with D-gal-induced aging. However, the source of the ROS in the CAS and the mechanisms of age-related hearing loss (ARHL) have yet to be elucidated. In the present study, male Sprague Dawley rats were administered a daily injection of D-gal (150, 300 and 500 mg/kg, respectively) for eight weeks. All three doses of D-gal caused a significant increase in the expression of NOX2, 8-hydroxy-2-deoxyguanosine, a biomarker of DNA oxidative damage, and uncoupling protein 2, together with a decrease in the mitochondrial total antioxidant capabilities in the auditory cortex, as compared with the control rats (injected daily with the same volume of 0.9% saline for eight weeks). The levels of the mtDNA CD were also increased in the auditory cortex of the D-gal-induced aging rats. These findings suggest that both NOX- and mitochondria-associated ROS generation may contribute to mtDNA oxidative damage in the auditory cortex of the CAS of D-gal-induced aging rats. This study may provide novel insight into the development of ARHL.
D-galactose; auditory cortex; oxidative damage; mitochondria; age-related hearing loss
Albendazole is a broad-spectrum parasiticide with high effectiveness and low host toxicity. No method is currently available for measuring albendazole and its metabolites in silkworm hemolymph. This study describes a rapid, selective, sensitive, synchronous and reliable detection method for albendazole and its metabolites in silkworm hemolymph using ultrafast liquid chromatography tandem triple quadrupole mass spectrometry (UFLC-MS/MS). The method is liquid-liquid extraction followed by UFLC separation and quantification in an MS/MS system with positive electrospray ionization in multiple reaction monitoring mode. Precursor-to-product ion transitions were monitored at 266.100 to 234.100 for albendazole (ABZ), 282.200 to 208.100 for albendazole sulfoxide (ABZSO), 298.200 to 159.100 for albendazole sulfone (ABZSO2) and 240.200 to 133.100 for albendazole amino sulfone (ABZSO2-NH2). Calibration curves had good linearities with R2 of 0.9905–0.9972. Limits of quantitation (LOQs) were 1.32 ng/mL for ABZ, 16.67 ng/mL for ABZSO, 0.76 ng/mL for ABZSO2 and 5.94 ng/mL for ABZSO2-NH2. Recoveries were 93.12%–103.83% for ABZ, 66.51%–108.51% for ABZSO, 96.85%–105.6% for ABZSO2 and 96.46%–106.14% for ABZSO2-NH2, (RSDs <8%). Accuracy, precision and stability tests showed acceptable variation in quality control (QC) samples. This analytical method successfully determined albendazole and its metabolites in silkworm hemolymph in a pharmacokinetic study. The results of single-dose treatment suggested that the concentrations of ABZ, ABZSO and ABZSO2 increased and then fell, while ABZSO2-NH2 level was low without obvious change. Different trends were observed for multi-dose treatment, with concentrations of ABZSO and ABZSO2 rising over time.
Hyperuricemia is associated with multiple diseases, including gout, cardiovascular disease, and renal disease. Serum urate is highly heritable, yet association studies of single nucleotide polymorphisms (SNPs) and serum uric acid explain a small fraction of the heritability. Whether copy number polymorphisms (CNPs) contribute to uric acid levels is unknown.
We assessed copy number on a genome-wide scale among 8,411 individuals of European ancestry (EA) who participated in the Atherosclerosis Risk in Communities (ARIC) study. CNPs upstream of the urate transporter SLC2A9 on chromosome 4p16.1 are associated with uric acid (χ2df2=3545, p=3.19×10-23). Effect sizes, expressed as the percentage change in uric acid per deleted copy, are most pronounced among women (3.974.935.87 [ 2.55097.5 denoting percentiles], p=4.57×10-23) and independent of previously reported SNPs in SLC2A9 as assessed by SNP and CNP regression models and the phasing SNP and CNP haplotypes (χ2df2=3190,p=7.23×10-08). Our finding is replicated in the Framingham Heart Study (FHS), where the effect size estimated from 4,089 women is comparable to ARIC in direction and magnitude (1.414.707.88, p=5.46×10-03).
This is the first study to characterize CNPs in ARIC and the first genome-wide analysis of CNPs and uric acid. Our findings suggests a novel, non-coding regulatory mechanism for SLC2A9-mediated modulation of serum uric acid, and detail a bioinformatic approach for assessing the contribution of CNPs to heritable traits in large population-based studies where technical sources of variation are substantial.
Copy number polymorphism; Hyperuricemia; Genomewide association study
The rat sarcoma-extracellular signal regulated kinase mitogen-activated protein kinases pathway, one of the most ancient signaling pathways, is crucial for the defense against Bombyx mori nucleopolyhedrovirus (BmNPV) infection. Sprouty (Spry) proteins can inhibit the activity of this pathway by receptor tyrosine kinases. We cloned and identified a new B. mori gene with a Spry domain similar to the Spry proteins of other organisms, such as fruitfly, mouse, human, chicken, Xenopus and zebrafish, and named it BmSpry. The gene expression analysis showed that BmSpry was transcribed in all of the examined tissues and in all developmental stages from embryo to adult. BmSpry also induced expression of BmNPV in the cells. Our results indicated: (1) the knock-down of BmSpry led to increased BmNPV replication and silkworm larvae mortality; (2) over-expression of BmSpry led to reduced BmNPV replication; and (3) BmSpry regulated the activation of ERK and inhibited BmNPV replication. These results showed that BmSpry plays a crucial role in the antiviral defense of the silkworm both in vitro and in vivo.
Background. Efficacy of adding bevacizumab in first-line chemotherapy of metastatic colorectal cancer (mCRC)
has been controversial. The aim of this study is to gather current data to analyze efficacy of adding bevacizumab to the most used combination first-line chemotherapy in mCRC,
based on the 2012 meta-analysis reported by Macedo et al. Methods. Medline, EMBASE and Cochrane library,
meeting presentations and abstracts were searched. Eligible studies were randomized controlled trials (RCTs)
which evaluated first-line chemotherapy with or without bevacizumab in mCRC.
The extracting data were included and examined in the meta-analysis according to the type of chemotherapy regimen. Results.
Seven trials, totaling 3436 patients, were analyzed.
Compared with first-line chemothery alone, the adding of bevacizumab did not show clinical benefit for OS both in first-line therapy and the most used combination chemotherapy (HR = 0.89; 95% CI = 0.78–1.02; P = 0.08; HR = 0.93; 95% CI = 0.83–1.05; P = 0.24). In contrast with OS, the addition of bevacizumab resulted in significant improvement for PFS
(HR = 0.68; 95% CI = 0.59–0.78; P < 0.00001). Moreover, it also demonstrated statistical benefit for PFS in the most used combination first-line chemotherapy
(HR = 0.84; 95% CI = 0.75–0.94; P = 0.002). And the subgroup analysis indicated only capacitabine-based regimens were beneficial. Conclusions. This meta-analysis shows that the addition of bevacizumab to FOLFOX/FOLFIRI/XELOX regimens might not be beneficial in terms of OS. Benefit has been seen when PFS has been taken into account.
In subgroup analysis, benefit adding bevacizumab has been seen when capecitabine-based regimens are used.
Further studies are warranted to explore the combination with bevacizumab.
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Multivariate phenotypes are frequently encountered in genetic association studies. The purpose of analyzing multivariate phenotypes usually includes discovery of novel genetic variants of pleiotropy effects, that is, affecting multiple phenotypes, and the ultimate goal of uncovering the underlying genetic mechanism. In recent years, there have been new method development and application of existing statistical methods to such phenotypes. In this paper, we provide a review of the available methods for analyzing association between a single marker and a multivariate phenotype consisting of the same type of components (e.g., all continuous or all categorical) or different types of components (e.g., some are continuous and others are categorical). We also reviewed causal inference methods designed to test whether the detected association with the multivariate phenotype is truly pleiotropy or the genetic marker exerts its effects on some phenotypes through affecting the others.
Patients with chronic myelogenous leukemia (CML) respond well to tyrosine kinase inhibitors (TKIs) of the Bcr-Abl oncoprotein. However, intolerance and resistance to these agents remains a challenge, and TKI’s are unable to eradicate rare leukemia-initiating cells. Leukemia treatment would benefit from a better understanding of molecular signals that are necessary for the survival of leukemia-initiating cells but dispensable for normal hematopoietic stem cells. Leukemia-initiating cells in CML can arise from myeloid progenitor cells, a population that we have reported in normal hematopoiesis to depend on the RNA-editing enzyme ADAR1 (adenosine deaminase acting on RNA-1). We now report that Bcr-Abl transformed leukemic cells were ADAR1-dependent in a conditional ADAR1 knockout mouse model. ADAR1 deletion reversed leukocytosis and splenomegaly, and preferentially depleted primitive Lin-Sca+Kit+ (LSK) leukemic cells but not LSK cells lacking the leukemic oncoprotein. ADAR1 deletion ultimately normalized the peripheral white blood count, eliminating leukemic cells as assessed by PCR. These results uncover a novel requirement for ADAR1 in myeloid leukemic cells and indicate that ADAR1 may comprise a new molecular target for CML-directed therapeutics.
Circulating homocysteine levels (tHcy), a product of the folate one carbon metabolism pathway (FOCM) through the demethylation of methionine, are heritable and are associated with an increased risk of common diseases such as stroke, cardiovascular disease (CVD), cancer and dementia. The FOCM is the sole source of de novo methyl group synthesis, impacting many biological and epigenetic pathways. However, the genetic determinants of elevated tHcy (hyperhomocysteinemia), dysregulation of methionine metabolism and the underlying biological processes remain unclear. We conducted independent genome-wide association studies and a meta-analysis of methionine metabolism, characterized by post-methionine load test tHcy, in 2,710 participants from the Framingham Heart Study (FHS) and 2,100 participants from the Vitamin Intervention for Stroke Prevention (VISP) clinical trial, and then examined the association of the identified loci with incident stroke in FHS. Five genes in the FOCM pathway (GNMT [p = 1.60×10−63], CBS [p = 3.15×10−26], CPS1 [p = 9.10×10−13], ALDH1L1 [p = 7.3×10−13] and PSPH [p = 1.17×10−16]) were strongly associated with the difference between pre- and post-methionine load test tHcy levels (ΔPOST). Of these, one variant in the ALDH1L1 locus, rs2364368, was associated with incident ischemic stroke. Promoter analyses reveal genetic and epigenetic differences that may explain a direct effect on GNMT transcription and a downstream affect on methionine metabolism. Additionally, a genetic-score consisting of the five significant loci explains 13% of the variance of ΔPOST in FHS and 6% of the variance in VISP. Association between variants in FOCM genes with ΔPOST suggest novel mechanisms that lead to differences in methionine metabolism, and possibly the epigenome, impacting disease risk. These data emphasize the importance of a concerted effort to understand regulators of one carbon metabolism as potential therapeutic targets.
Elevated homocysteine (tHcy) is strongly associated with risk for common disorders such as stroke, cardiovascular disease and Alzheimer disease. Lowering tHcy levels has proven to have variable success in reducing clinical risk, so the question remains, “Are we correctly targeting these disorders by lowering tHcy?” Understanding folate one-carbon metabolism pathway (FOCM) genetic variation will aid us in developing new targets for therapy. The FOCM is essential in regulation of the epigenome, which controls genes in ways beyond nucleotide sequence. We present data generated from stroke-only and general populations where we identify strong association of genetic risk factors for variation in one-carbon metabolism function, characterized by the post-methionine load test. We show that GNMT harbors genetic and epigenetic differences that influence gene function, which may have downstream effects on the epigenome of the cell, affecting disease risk. We developed a genetic risk score that predicts post-methionine load homocysteine levels that may be useful in clinic. Finally, we identified a novel association between ischemic stroke and ALDH1L1, which emphasizes the clinical importance of this work. Our results highlight the importance of a concerted effort to target the FOCM (beyond tHcy) and parallel pathways in future pharmacogenetic work using the genetic variation we describe here.
Freezing of gait (FOG) is a complicated gait disturbance in Parkinson's disease (PD) and a relevant subclinical predictor algorithm is lacking. The main purpose of this study is to explore the potential value of surface electromyograph (sEMG) and plasma α-synuclein levels as predictors of the FOG seen in PD. 21 PD patients and 15 normal controls were recruited. Motor function was evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and Freezing of gait questionnaire (FOG-Q). Simultaneously, gait analysis was also performed using VICON capture system in PD patients and sEMG data was recorded as well. Total plasma α-synuclein was quantitatively assessed by Luminex assay in all participants. Recruited PD patients were classified into two groups: PD patients with FOG (PD+FOG) and without FOG (PD-FOG), based on clinical manifestation, the results of the FOG-Q and VICON capture system. PD+FOG patients displayed higher FOG-Q scores, decreased walking speed, smaller step length, smaller stride length and prolonged double support time compared to the PD-FOG in the gait trial. sEMG data indicated that gastrocnemius activity in PD+FOG patients was significantly reduced compared to PD-FOG patients. In addition, plasma α-synuclein levels were significantly decreased in the PD+FOG group compared to control group; however, no significant difference was found between the PD+FOG and PD-FOG groups. Our study revealed that gastrocnemius sEMG could be used to evaluate freezing gait in PD patients, while plasma α-synuclein might discriminate freezing of gait in PD patients from normal control, though no difference was found between the PD+FOG and PD-FOG groups.
Disrupted white matter integrity and abnormal cortical thickness are widely reported in the pathophysiology of obsessive-compulsive disorder (OCD). However, the relationship between alterations in white matter connectivity and cortical thickness in OCD is unclear. In addition, the heritability of this relationship is poorly understood. To investigate the relationship of white matter microstructure with cortical thickness, we measure fractional anisotropy (FA) of white matter in 30 OCD patients, 19 unaffected siblings and 30 matched healthy controls. Then, we take those regions of significantly altered FA in OCD patients compared with healthy controls to perform fiber tracking. Next, we calculate the fiber quantity in the same tracts. Lastly, we compare cortical thickness in the target regions of those tracts. Patients with OCD exhibited decreased FA in cingulum, arcuate fibers near the superior parietal lobule, inferior longitudinal fasciculus near the right superior temporal gyrus and uncinate fasciculus. Siblings showed reduced FA in arcuate fibers near the superior parietal lobule and anterior limb of internal capsule. Significant reductions in both fiber quantities and cortical thickness in OCD patients and their unaffected siblings were also observed in the projected brain areas when using the arcuate fibers near the left superior parietal lobule as the starting points. Reduced FA in the left superior parietal lobule was observed not only in patients with OCD but also in their unaffected siblings. Originated from the superior parietal lobule, the number of fibers was also found to be decreased and the corresponding cortical regions were thinner relative to controls. The linkage between disrupted white matter integrity and the abnormal cortical thickness may be a vulnerability marker for OCD.
Objective: The goal of the current investigation was to explore whether salivary DJ-1 could be a potential biomarker for monitoring disease progression in Parkinson's disease (PD) by evaluating the association between salivary DJ-1 concentrations and nigrostriatal dopaminergic function.
Methods: First, in 74 patients with PD and 12 age-matched normal controls, single photon emission computed tomography (SPECT) imaging with labeled dopamine transporters (DAT) (99mTc-TRODAT-1), which has been used for measuring DAT density in PD was prformed. Then, the DJ-1 level in their saliva was analyzed by quantitative and sensitive Luminex assay and compared to caudate or putamen DAT density. Finally, based on the above, our cross-section study was carried out in 376 research volunteers (285 patients with PD and 91 healthy controls) to measure salivary DJ-1 level.
Results: From our analysis, we found a correlation between salivary concentration of DJ-1 and putamen nucleus uptake of 99mTc-TRODAT-1 in the PD group. Although salivary DJ-1 levels were not affected by UPDRS scores, gender, age, and pharmacotherapy, DJ-1 levels in H&Y 4 stage of PD were higher than those in H&Y 1-3 stage as well as those in healthy controls. Salivary DJ-1 also decreased significantly in mixed type PD patients compared to the tremor-dominant type (TDT) and akinetic-rigid dominant type (ARDT) PD patients.
Conclusions: According to the investigation in a large cohort, we reported for the first time the prognostic potential of the salivary DJ-1 as a biomarker for evaluating nigrostriatal dopaminergic function in PD.
DJ-1; saliva; Parkinson's disease; dopamine transporter; SPECT
In conducting genome-wide association studies (GWAS), analytical approaches leveraging biological information may further understanding of the pathophysiology of clinical traits. To discover novel associations with estimated glomerular filtration rate (eGFR), a measure of kidney function, we developed a strategy for integrating prior biological knowledge into the existing GWAS data for eGFR from the CKDGen Consortium. Our strategy focuses on single nucleotide polymorphism (SNPs) in genes that are connected by functional evidence, determined by literature mining and gene ontology (GO) hierarchies, to genes near previously validated eGFR associations. It then requires association thresholds consistent with multiple testing, and finally evaluates novel candidates by independent replication. Among the samples of European ancestry, we identified a genome-wide significant SNP in FBXL20 (P = 5.6 × 10−9) in meta-analysis of all available data, and additional SNPs at the INHBC, LRP2, PLEKHA1, SLC3A2 and SLC7A6 genes meeting multiple-testing corrected significance for replication and overall P-values of 4.5 × 10−4–2.2 × 10−7. Neither the novel PLEKHA1 nor FBXL20 associations, both further supported by association with eGFR among African Americans and with transcript abundance, would have been implicated by eGFR candidate gene approaches. LRP2, encoding the megalin receptor, was identified through connection with the previously known eGFR gene DAB2 and extends understanding of the megalin system in kidney function. These findings highlight integration of existing genome-wide association data with independent biological knowledge to uncover novel candidate eGFR associations, including candidates lacking known connections to kidney-specific pathways. The strategy may also be applicable to other clinical phenotypes, although more testing will be needed to assess its potential for discovery in general.
RecQL4, one of the five human RecQ helicases, is crucial for genomic stability and RecQL4 when mutated leads to premature aging phenotypes in humans. Unlike other human RecQ helicases, RecQL4 is found both in the nucleus and the cytoplasm. While the nuclear localization signal (NLS) and the retention domain at the N-terminus are responsible for the nuclear localization of RecQL4, the signal for its cytoplasmic localization is essentially unknown. In this study, two functional nuclear exporting signals (NESs; pNES2 and pNES3) were identified at the C-terminus of RecQL4. Deletion of pNES2 drastically diminished the cytoplasmic localization of RecQL4. Strikingly, addition of ubiquitination tail at the C-terminus of RecQL4 substantially enriched the cytoplasmic fraction of RecQL4 only in the presence of functional pNES2. Immunofluorescence studies revealed that the cytoplasmic RecQL4 was localized in mitochondria. Consistent with its mitochondrial localization, a regulatory role for RecQL4 in the maintenance of mitochondrial DNA (mtDNA) copy number was demonstrated. Elevation of ectopic expression of RecQL4 increased the mtDNA copy number in HEK293 cells while RecQL4 knock down markedly decreased the mtDNA copy number in U2OS cells. Additionally, a substantially increased level of mitochondrial superoxide production, and a markedly decreased repair capacity for oxidative DNA damage were observed in the mitochondria of both RecQL4 deficient human fibroblasts and RecQL4-suppressed cancer cells. These data strongly suggest a regulatory role for RecQL4 in mitochondrial stability and function. Collectively, our study demonstrates that NES-mediated RecQL4 export to the cytoplasm is essential for the maintenance of mitochondrial genome stability.
RecQL4; Nuclear exporting signal (NES); Mitochondrial co-localization; ROS (Reactive oxygen species); Oxidative damage repair
Despite the complexity and variety of biological oscillators, their core design invariably includes an essential negative feedback loop. In the Xenopus laevis embryonic cell cycle oscillator, this loop consists of the kinase cyclin B-Cdk1 and the ubiquitin ligase APC/CCdc20; active Cdk1 activates APC/CCdc20, which then brings about cyclin B degradation and inactivates Cdk1. Here we ask how this negative feedback loop functions quantitatively, with the aim of understanding what mechanisms keep the Cdk1-APC/CCdc20 system from settling into a stable steady state with intermediate levels of Cdk1 and APC/CCdc20 activity. We found that the system operates as a time-delayed, digital switch, with a time lag of ~15 min between Cdk1 and APC/CCdc20 activation and a tremendously high degree of ultrasensitivity (nH ≈ 17). Computational modeling shows how these attributes contribute to the generation of robust, clock-like oscillations. Principles uncovered here may also apply to other activator-repressor oscillators and help in designing robust synthetic clocks.
Elevated blood pressure (BP) is a major risk factor for cardiovascular disease. Several studies have noted a consistent maternal effect on BP; consequently, mitochondrial DNA (mtDNA) variation has become an additional target of investigation of the missing BP heritability. Analyses of common mtDNA polymorphisms, however, have not found evidence of association with hypertension. To explore associations of relatively rare (frequency < 5%) mtDNA variants with BP, we identified uncommon/rare variants through sequencing the entire mitochondrial genome in 32 unrelated individuals with extreme-high BP in the Framingham Heart Study (FHS) and genotyped 40 mtSNPs in 7,219 FHS participants. The nonsynonymous mtSNP 5913G>A (Asp4Asn) in the cytochrome c oxidase subunit 1 of Complex IV demonstrated significant associations with BP and fasting blood glucose (FBG) levels. Individuals with the rare 5913A allele had, on average, 7 mm Hg higher systolic BP at baseline (Pempirical = 0.05) and 17 mg/dL higher mean FBG over 25 years of follow up (Pempirical = 0.009). Significant associations with FBG levels were also detected for nonsynonymous mtSNP 3316G>A (Ala4Thr) in the NADH dehydrogenase subunit 1 of Complex I. On average, individuals with rare allele 3316A had 17 and 25 mg/dL higher FBG at baseline (Pempirical = 0.01) and over 25 years of follow up (Pempirical = 0.007). Our findings provide the first evidence of putative association of variants in the mitochondrial genome with SBP and FBG in the general population. Replication in independent samples, however, is needed to confirm these putative associations.
Mitochondrial genome; Association study; Genetics; Hypertension; Diabetes