Genetic Variation in the REL Gene Increases Risk of Behcet’s Disease in a Chinese Han Population but That of PRKCQ Does Not

Genome-wide association studies (GWAS) and candidate gene studies have identified the REL and PRKCQ genes as risk loci for various autoimmune diseases. The purpose of the present study was to investigate the association of the REL and PRKCQ genes with Behcet’s disease (BD) in a Chinese Han population. A case-control study was conducted on three single nucleotide polymorphisms (SNPs), rs13031237, rs702873, and rs842647 of the REL gene and three SNPs (rs4750316, rs11258747, and rs947474) of the PRKCQ gene using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in a total of 623 BD patients and 1,074 healthy controls. Multiple variables were assessed, including age, sex distribution, and extra-ocular findings. In the present study, the frequencies of rs842647 GG genotypes and rs842647 G alleles were significantly higher in patients than in controls and those of the rs842647 AG genotypes were lower in patients than in controls [GG genotype: Bonferroni corrected P-value for gender adjustment (P_c^a) = 0.0074, odds ratio (OR) = 1.63; G allele: P_c^a = 0.0072, OR = 1.57; AG genotype: P_c^a = 0.024, OR = 0.63, respectively]. No statistically significant differences in the frequencies of rs702873, rs13031237, rs4750316, rs11258747, and rs947474 between BD patients and controls were observed. Stratification analysis indicated that the REL rs842647 polymorphism was associated with BD patients with skin lesions. No significant association of the other five SNPs between BD patients with other extra-ocular findings, including genital ulcer, arthritis, and positive pathergy test results was found. The REL rs842647 polymorphism may be a susceptibility factor for BD pathogenesis and skin lesions, which indicate that c-Rel may be involved in the pathogenesis and skin lesions of BD through the NF-κB pathway.     

Exome-Wide Association Study Identified New Risk Loci for Hirschsprung’s Disease

Hirschsprung disease (HSCR) is a rare congenital disease caused by impaired proliferation and migration of neural crest cells. In this study, we aimed to investigate the genetic loci involved in the pathogenesis of HSCR. The exome-wide scan was performed to screen the genetic variants with minor allele frequency (MAF)?<?0.05 in exonic regions. Candidate mutation type and the wild type were overexpressed to investigate the affection on cell proliferation and migration. We found that ten variants were associated with HSCR at P?<?10^?4 in the single-variant analysis while ten genes were also associated with HSCR at P?<?10^?4 in the optimized sequence kernel association test (SKAT-O) test analysis. Among these SNPs, the missense variants catechol-O-methyltransferase (COMT) (rs6267) and armadillo repeat gene deleted in velocardiofacial syndrome (ARVCF) (rs80068543) indicated an ectopic expression in colon tissues of HSCR patients. The Ala72Ser variant in COMT induced proliferation suppression through NOTCH signal pathway, while the ARVCF affected cell migration via the downregulating of RHOA and ROC. In conclusion, this exome array study identified the COMT and ARVCF missense coding variants as candidate loci for HSCR. The finding implies the abnormal variant of COMT and ARVCF may account for the pathogenesis of HSCR.     

Genetic Variants in GAPDH Confer Susceptibility to Sporadic Parkinson’s Disease in a Chinese Han Population

Background

Accumulating evidence has demonstrated that the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a part of Lewy body inclusions and involves the pathogenesis of Parkinson’s disease (PD). However, it remains unknown whether or not genetic variation at the GAPDH locus contributes to the risk for PD.

Methods

A total of 302 sporadic PD patients and 377 control subjects were recruited in our study for assessing two single nucleotide polymorphisms (rs3741918 and rs1060619) in the GAPDH gene. Both allelic association and additive models were used to analyze association between GAPDH variants and risk for PD.

Results

Both polymorphisms were significantly associated with risk for PD after correction by Bonferroni multiple testing. The minor allele of rs3741918 was associated with decreased risk of sporadic PD (allelic contrast, OR = 0.74, 95% CI: 0.59–0.93, corrected P = 0.028; additive model, OR = 0.73, 95% CI: 0.58–0.92, corrected P = 0.018). While for the rs1060619 locus, the minor allele conferred increased risk for PD (allelic contrast, OR = 1.41, 95% CI: 1.14–1.75, corrected P = 0.007; additive model, OR = 1.43, 95% CI: 1.15–1.79, corrected P = 0.002).

Conclusion

Our study indicates that GAPDH variants confer susceptibility to sporadic PD in a Chinese Han population, which is consistent with the role of GAPDH protein in neuronal apoptosis. To our knowledge, this is the first study of genetic association between GAPDH locus and risk for PD in the Chinese population.     

PICALM rs3851179 Variant Confers Susceptibility to Alzheimer’s Disease in Chinese Population

The association between PICALM rs3851179 variant and Alzheimer’s disease (AD) has been well established by previous genome-wide association studies (GWAS) and candidate gene studies in European population. Recent studies investigated the association between PICALM rs3851179 and AD susceptibility in Chinese population. However, these studies reported consistent and inconsistent results. Here, we selected 9435 samples including 3704 AD cases and 5731 controls from previous studies and evaluated this association using a meta-analysis method for additive model. We did not observe significant genetic heterogeneity in Chinese population. Our results indicate significant association between PICALM rs3851179 and AD in Chinese population. The sensitivity analysis indicates that the association between rs3851179 and AD did not vary substantially. The regression analysis suggests no significant publication bias. In summary, this updated meta-analysis highlights the involvement of PICALM rs3851179 variant in Alzheimer’s disease susceptibility in Chinese population.     

Genetic Heterogeneity of Susceptibility Gene in Different Ethnic Populations: Refining Association Study of PTPN22 for Graves’ Disease in a Chinese Han Population

In our previous studies, we presumed subtypes of Graves’ disease (GD) may be caused by different major susceptibility genes or different variants of a single susceptibility gene. However, more evidence is needed to support this hypothesis. Single-nucleotide polymorphism (SNP) rs2476601 in PTPN22 is the susceptibility loci of GD in the European population. However, this polymorphism has not been found in Asian populations. Here, we investigate whether PTPN22 is the susceptibility gene for GD in Chinese population and further determine the susceptibility variant of PTPN22 in GD. We conducted an imputation analysis based on the results of our genome-wide association study (GWAS) in 1,536 GD patients and 1,516 control subjects. Imputation revealed that 255 common SNPs on a linkage disequilibrium (LD) block containing PTPN22 were associated with GD (P<0.05). Nine tagSNPs that captured the 255 common variants were selected to be further genotyped in a large cohort including 4,368 GD patients and 4,350 matched controls. There was no significant difference between the nine tagSNPs (P>0.05) in either the genotype distribution or allelic frequencies between patients and controls in the replication study. Although the combined analysis exhibited a weak association signal (P _combined = 0.003263 for rs3811021), the false positive report probability (FPRP) analysis indicated it was most likely a false positive finding. Our study did not support an association of common SNPs in PTPN22 LD block with GD in Chinese Han population. This suggests that GD in different ethnic population is probably caused by distinct susceptibility genes.     

Expression of Novel Alzheimer’s Disease Risk Genes in Control and Alzheimer’s Disease Brains

Late onset Alzheimer’s disease (LOAD) etiology is influenced by complex interactions between genetic and environmental risk factors. Large-scale genome wide association studies (GWAS) for LOAD have identified 10 novel risk genes: ABCA7, BIN1, CD2AP, CD33, CLU, CR1, EPHA1, MS4A6A, MS4A6E, and PICALM. We sought to measure the influence of GWAS single nucleotide polymorphisms (SNPs) and gene expression levels on clinical and pathological measures of AD in brain tissue from the parietal lobe of AD cases and age-matched, cognitively normal controls. We found that ABCA7, CD33, and CR1 expression levels were associated with clinical dementia rating (CDR), with higher expression being associated with more advanced cognitive decline. BIN1 expression levels were associated with disease progression, where higher expression was associated with a delayed age at onset. CD33, CLU, and CR1 expression levels were associated with disease status, where elevated expression levels were associated with AD. Additionally, MS4A6A expression levels were associated with Braak tangle and Braak plaque scores, with elevated expression levels being associated with more advanced brain pathology. We failed to detect an association between GWAS SNPs and gene expression levels in our brain series. The minor allele of rs3764650 in ABCA7 is associated with age at onset and disease duration, and the minor allele of rs670139 in MS4A6E was associated with Braak tangle and Braak plaque score. These findings suggest that expression of some GWAS genes, namely ABCA7, BIN1, CD33, CLU, CR1 and the MS4A family, are altered in AD brains.     

Progranulin Gene Delivery Protects Dopaminergic Neurons in a Mouse Model of Parkinson’s Disease

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by tremor, rigidity and akinesia/bradykinesia resulting from the progressive loss of nigrostriatal dopaminergic neurons. To date, only symptomatic treatment is available for PD patients, with no effective means of slowing or stopping the progression of the disease. Progranulin (PGRN) is a 593 amino acid multifunction protein that is widely distributed throughout the CNS, localized primarily in neurons and microglia. PGRN has been demonstrated to be a potent regulator of neuroinflammation and also acts as an autocrine neurotrophic factor, important for long-term neuronal survival. Thus, enhancing PGRN expression may strengthen the cells resistance to disease. In the present study, we have used the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD to investigate the possible use of PGRN gene delivery as a therapy for the prevention or treatment of PD. Viral vector delivery of the PGRN gene was an effective means of elevating PGRN expression in nigrostriatal neurons. When PGRN expression was elevated in the SN_C, nigrostriatal neurons were protected from MPTP toxicity in mice, along with a preservation of striatal dopamine content and turnover. Further, protection of nigrostriatal neurons by PGRN gene therapy was accompanied by reductions in markers of MPTP-induced inflammation and apoptosis as well as a complete preservation of locomotor function. We conclude that PGRN gene therapy may have beneficial effects in the treatment of PD.     

Linkage Analysis in Autoimmune Addison’s Disease: NFATC1 as a Potential Novel Susceptibility Locus

BackgroundAutoimmune Addison’s disease (AAD) is a rare, highly heritable autoimmune endocrinopathy. It is possible that there may be some highly penetrant variants which confer disease susceptibility that have yet to be discovered.MethodsDNA samples from 23 multiplex AAD pedigrees from the UK and Norway (50 cases, 67 controls) were genotyped on the Affymetrix SNP 6.0 array. Linkage analysis was performed using Merlin. EMMAX was used to carry out a genome-wide association analysis comparing the familial AAD cases to 2706 UK WTCCC controls. To explore some of the linkage findings further, a replication study was performed by genotyping 64 SNPs in two of the four linked regions (chromosomes 7 and 18), on the Sequenom iPlex platform in three European AAD case-control cohorts (1097 cases, 1117 controls). The data were analysed using a meta-analysis approach.ResultsIn a parametric analysis, applying a rare dominant model, loci on chromosomes 7, 9 and 18 had LOD scores >2.8. In a non-parametric analysis, a locus corresponding to the HLA region on chromosome 6, known to be associated with AAD, had a LOD score >3.0. In the genome-wide association analysis, a SNP cluster on chromosome 2 and a pair of SNPs on chromosome 6 were associated with AAD (P <5x10^-7). A meta-analysis of the replication study data demonstrated that three chromosome 18 SNPs were associated with AAD, including a non-synonymous variant in the NFATC1 gene.ConclusionThis linkage study has implicated a number of novel chromosomal regions in the pathogenesis of AAD in multiplex AAD families and adds further support to the role of HLA in AAD. The genome-wide association analysis has also identified a region of interest on chromosome 2. A replication study has demonstrated that the NFATC1 gene is worthy of future investigation, however each of the regions identified require further, systematic analysis.     

Calpastatin Gene (CAST) Is Not Associated with Late Onset Sporadic Parkinson’s Disease in the Han Chinese Population

Recent studies point to an association between the late-onset sporadic Parkinson’s disease (PD) and single nucleotide polymorphisms (SNPs) rs1559085 and rs27852 in Ca²⁺-dependent protease calpain inhibitor calpastatin (CAST) gene. This finding is of interest since loss of CAST activity could result in over activated calpain, potentially leading to Ca²⁺ dysregulation and loss of substantia nigra neurons in PD. We explored the association between CAST SNPs and late-onset sporadic PD in the Han Chinese population. The study included 615 evaluable patients (363 male, 252 female) with PD and 636 neurologically healthy controls (380 male, 256 female) matched for age, gender, ethnicity, and area of residence. PD cases were identified from the PD cohort of the Chinese National Consortium on Neurodegenerative Diseases (www.chinapd.cn). A total of 24 tag-SNPs were genotyped capturing 95% of the genetic variation across the CAST gene. There was no association found between any of the polymorphisms and PD in all models tested (co-dominant, dominant-effect and recessive-effect). Similarly, none of the common haplotypes was associated with a risk for PD. Our data do not support a significant association between the CAST gene polymorphisms and late onset sporadic PD in the Han Chinese population.     

Characterization of Interstitial Cajal Progenitors Cells and Their Changes in Hirschsprung’s Disease

Interstitial cells of Cajal (ICC) are critical to gastrointestinal motility. The phenotypes of ICC progenitors have been observed in the mouse gut, but whether they exist in the human colon and what abnormal changes in their quantity and ultrastructure are present in Hirschsprung’s disease (HSCR) colon remains uncertain. In this study, we collected the surgical resection of colons, both proximal and narrow segments, from HSCR patients and normal controls. First, we identified the progenitor of ICC in normal adult colon using immunofluorescent localization techniques with laser confocal microscopy. Next, the progenitors were sorted to observe their morphology. We further applied flow cytometry to examine the content of ICC progenitors in these fresh samples. The ultrastructural changes in the narrow and proximal parts of the HSCR colon were observed using transmission electron microscopy (TEM) and were compared with the normal adult colon. The presumed early progenitor (c-Kit^lowCD34⁺Igf1r⁺) and committed progenitor (c-Kit⁺CD34⁺Igf1r⁺) of ICC exist in adult normal colon as well as in the narrow and proximal parts of the HSCR colon. However, the proportions of mature, early and committed progenitors of ICC were dramatically reduced in the narrow segment of the HSCR colon. The proportions of mature and committed progenitors of ICC in the proximal segment of the HSCR colon were lower than in the adult normal colon. Ultrastructurally, ICC, enteric nerves, and smooth muscle in the narrow segment of the HSCR colon showed severe injury, including swollen vacuola or ted mitochondria, disappearance of mitochondrial cristae, dilated rough endoplasmic reticulum, vesiculation and degranulation, and disappearance of the caveolae on the ICC membrane surface. The contents of ICC and its progenitors in the narrow part of the HSCR colon were significantly decreased than those of adult colon, which may be associated with HSCR pathogenesis.     

Tau Overexpression Impacts a Neuroinflammation Gene Expression Network Perturbed in Alzheimer’s Disease

Filamentous inclusions of the microtubule-associated protein, tau, define a variety of neurodegenerative diseases known as tauopathies, including Alzheimer’s disease (AD). To better understand the role of tau-mediated effects on pathophysiology and global central nervous system function, we extensively characterized gene expression, pathology and behavior of the rTg4510 mouse model, which overexpresses a mutant form of human tau that causes Frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). We found that the most predominantly altered gene expression pathways in rTg4510 mice were in inflammatory processes. These results closely matched the causal immune function and microglial gene-regulatory network recently identified in AD. We identified additional gene expression changes by laser microdissecting specific regions of the hippocampus, which highlighted alterations in neuronal network activity. Expression of inflammatory genes and markers of neuronal activity changed as a function of age in rTg4510 mice and coincided with behavioral deficits. Inflammatory changes were tau-dependent, as they were reversed by suppression of the tau transgene. Our results suggest that the alterations in microglial phenotypes that appear to contribute to the pathogenesis of Alzheimer’s disease may be driven by tau dysfunction, in addition to the direct effects of beta-amyloid.     

SMG1 Identified as a Regulator of Parkinson’s Disease-Associated alpha-Synuclein through siRNA Screening

Synucleinopathies are a broad class of neurodegenerative disorders characterized by the presence of intracellular protein aggregates containing α-synuclein protein. The aggregated α-synuclein protein is hyperphosphorylated on serine 129 (S129) compared to the unaggregated form of the protein. While the precise functional consequences of S129 hyperphosphorylation are still being clarified, numerous in vitro and in vivo studies suggest that S129 phosphorylation is an early event in α-synuclein dysfunction and aggregation. Identifying the kinases and phosphatases that regulate this critical phosphorylation event may ultimately prove beneficial by allowing pharmacological mitigation of synuclein dysfunction and toxicity in Parkinson’s disease and other synucleinopathies. We report here the development of a high-content, fluorescence-based assay to quantitate levels of total and S129 phosphorylated α-synuclein protein. We have applied this assay to conduct high-throughput loss-of-function screens with siRNA libraries targeting 711 known and predicted human kinases and 206 phosphatases. Specifically, knockdown of the phosphatidylinositol 3-kinase related kinase SMG1 resulted in significant increases in the expression of pS129 phosphorylated α-synuclein (p-syn). Moreover, SMG1 protein levels were significantly reduced in brain regions with high p-syn levels in both dementia with Lewy bodies (DLB) and Parkinson’s disease with dementia (PDD). These findings suggest that SMG1 may play an important role in increased α-synuclein pathology during the course of PDD, DLB, and possibly other synucleinopathies.     

Novel Detox Gel Depot Sequesters β-Amyloid Peptides in a Mouse Model of Alzheimer’s Disease

Alzheimer’s disease (AD), a debilitating neurodegenerative disease is caused by aggregation and accumulation of a 39–43 amino acid peptide (amyloid β or Aβ) in brain parenchyma and cerebrovasculature. The rational approach would be to use drugs that interfere with Aβ–Aβ interaction and disrupt polymerization. Peptide ligands capable of binding to the KLVFF (amino acids 16–20) region in the Aβ molecule have been investigated as possible drug candidates. Retro-inverso (RI) peptide of this pentapeptide, ffvlk, has been shown to bind artificial fibrils made from Aβ with moderate affinity. We hypothesized that a ‘detox gel’, which is synthesized by covalently linking a tetrameric version of RI peptide ffvlk to poly(ethylene glycol) polymer chains will act like a ‘sink’ to capture Aβ peptides from the surrounding environment. We previously demonstrated that this hypothesis works in an in vitro system. The present study extended this hypothesis to an in vivo mouse model of AD and determined the therapeutic effect of our detox gel. We injected detox gel subcutaneously to AD model mice and analyzed brain levels of Aβ-42 and improvement in memory parameters. The results showed a reduction of brain amyloid burden in detox gel treated mice. Memory parameters in the treated mice improved. No undesirable immune response was observed. The data strongly suggest that our detox gel can be used as an effective therapy to deplete brain Aβ levels. Considering recent abandonment of failed antibody based therapies, our detox gel appears to have the advantage of being a non-immune based therapy.