Identification of Novel Susceptibility Loci for Kawasaki Disease in a Han Chinese Population by a Genome-Wide Association Study

Kawasaki disease (KD) is an acute systemic vasculitis syndrome that primarily affects infants and young children. Its etiology is unknown; however, epidemiological findings suggest that genetic predisposition underlies disease susceptibility. Taiwan has the third-highest incidence of KD in the world, after Japan and Korea. To investigate novel mechanisms that might predispose individuals to KD, we conducted a genome-wide association study (GWAS) in 250 KD patients and 446 controls in a Han Chinese population residing in Taiwan, and further validated our findings in an independent Han Chinese cohort of 208 cases and 366 controls. The most strongly associated single-nucleotide polymorphisms (SNPs) detected in the joint analysis corresponded to three novel loci. Among these KD-associated SNPs three were close to the COPB2 (coatomer protein complex beta-2 subunit) gene: rs1873668 (p = 9.52×10−5), rs4243399 (p = 9.93×10−5), and rs16849083 (p = 9.93×10−5). We also identified a SNP in the intronic region of the ERAP1 (endoplasmic reticulum amino peptidase 1) gene (rs149481, pbest = 4.61×10−5). Six SNPs (rs17113284, rs8005468, rs10129255, rs2007467, rs10150241, and rs12590667) clustered in an area containing immunoglobulin heavy chain variable regions genes, with pbest-values between 2.08×10−5 and 8.93×10−6, were also identified. This is the first KD GWAS performed in a Han Chinese population. The novel KD candidates we identified have been implicated in T cell receptor signaling, regulation of proinflammatory cytokines, as well as antibody-mediated immune responses. These findings may lead to a better understanding of the underlying molecular pathogenesis of KD

Targeted deletion of the C-terminus of the mouse adenomatous polyposis coli tumor suppressor results in neurologic phenotypes related to schizophrenia

Background: Loss of adenomatous polyposis coli (APC) gene function results in constitutive activation of the canonical Wnt pathway and represents the main initiating and rate-limiting event in colorectal tumorigenesis. APC is likely to participate in a wide spectrum of biological functions via its different functional domains and is abundantly expressed in the brain as well as in peripheral tissues. However, the neuronal function of APC is poorly understood. To investigate the functional role of Apc in the central nervous system, we analyzed the neurological phenotypes of Apc 1638T/1638T mice, which carry a targeted deletion of the 3′ terminal third of Apc that does not affect Wnt signaling. Results: A series of behavioral tests revealed a working memory deficit, increased locomotor activity, reduced anxiety-related behavior, and mildly decreased social interaction in Apc 1638T/1638T mice. Apc 1638T/1638T mice showed abnormal morphology of the dendritic spines and impaired long-term potentiation of synaptic transmission in the hippocampal CA1 region. Moreover, Apc 1638T/1638T mice showed abnormal dopamine and serotonin distribution in the brain. Some of these behavioral and neuronal phenotypes are related to symptoms and endophenotypes of schizophrenia. Conclusions: Our results demonstrate that the C-terminus of the Apc tumor suppressor plays a critical role in cognitive and neuropsychiatric functioning. This finding suggests a potential functional link between the C-terminus of APC and pathologies of the central nervous system

ITPKC Single Nucleotide Polymorphism Associated with the Kawasaki Disease in a Taiwanese Population

Kawasaki disease (KD) is characterized by systemic vasculitis with unknown etiology. Previous studies from Japan indicated that a gene polymorphism of ITPKC (rs28493229) is responsible for susceptibility to KD. We collected DNA samples from 1,531 Taiwanese subjects (341 KD patients and 1,190 controls) for genotyping ITPKC. In this study, no significant association was noted for the ITPKC polymorphism (rs28493229) between the controls and KD patients, although the CC genotype was overrepresented. We further combined our data with previously published case/control KD studies in the Taiwanese population and performed a meta-analysis. A significant association between rs28493229 and KD was found (Odds Ratio:1.36, 95% Confidence Interval 1.12–1.66). Importantly, a significant association was obtained between rs28493229 and KD patients with aneurysm formation (P = 0.001, under the recessive model). Taken together, our results indicated that C-allele of ITPKC SNP rs28493229 is associated with the susceptibility and aneurysm formation in KD patients in a Taiwanese population

Genetic Variation in the SLC8A1 Calcium Signaling Pathway Is Associated With Susceptibility to Kawasaki Disease and Coronary Artery Abnormalities.

BACKGROUND: Kawasaki disease (KD) is an acute pediatric vasculitis in which host genetics influence both susceptibility to KD and the formation of coronary artery aneurysms. Variants discovered by genome-wide association studies and linkage studies only partially explain the influence of genetics on KD susceptibility. METHODS AND RESULTS: To search for additional functional genetic variation, we performed pathway and gene stability analysis on a genome-wide association study data set. Pathway analysis using European genome-wide association study data identified 100 significantly associated pathways (P<5×10-4). Gene stability selection identified 116 single nucleotide polymorphisms in 26 genes that were responsible for driving the pathway associations, and gene ontology analysis demonstrated enrichment for calcium transport (P=1.05×10-4). Three single nucleotide polymorphisms in solute carrier family 8, member 1 (SLC8A1), a sodium/calcium exchanger encoding NCX1, were validated in an independent Japanese genome-wide association study data set (meta-analysis P=0.0001). Patients homozygous for the A (risk) allele of rs13017968 had higher rates of coronary artery abnormalities (P=0.029). NCX1, the protein encoded by SLC8A1, was expressed in spindle-shaped and inflammatory cells in the aneurysm wall. Increased intracellular calcium mobilization was observed in B cell lines from healthy controls carrying the risk allele. CONCLUSIONS: Pathway-based association analysis followed by gene stability selection proved to be a valuable tool for identifying risk alleles in a rare disease with complex genetics. The role of SLC8A1 polymorphisms in altering calcium flux in cells that mediate coronary artery damage in KD suggests that this pathway may be a therapeutic target and supports the study of calcineurin inhibitors in acute KD

Association of CCR2-CCR5 Haplotypes and CCL3L1 Copy Number with Kawasaki Disease, Coronary Artery Lesions, and IVIG Responses in Japanese Children

BACKGROUND: The etiology of Kawasaki Disease (KD) is enigmatic, although an infectious cause is suspected. Polymorphisms in CC chemokine receptor 5 (CCR5) and/or its potent ligand CCL3L1 influence KD susceptibility in US, European and Korean populations. However, the influence of these variations on KD susceptibility, coronary artery lesions (CAL) and response to intravenous immunoglobulin (IVIG) in Japanese children, who have the highest incidence of KD, is unknown. METHODOLOGY/PRINCIPAL FINDINGS: We used unconditional logistic regression analyses to determine the associations of the copy number of the CCL3L1 gene-containing duplication and CCR2-CCR5 haplotypes in 133 Japanese KD cases [33 with CAL and 25 with resistance to IVIG] and 312 Japanese controls without a history of KD. We observed that the deviation from the population average of four CCL3L1 copies (i.e., <or>four copies) was associated with an increased risk of KD and IVIG resistance (adjusted odds ratio (OR)=2.25, p=0.004 and OR=6.26, p=0.089, respectively). Heterozygosity for the CCR5 HHF*2 haplotype was associated with a reduced risk of both IVIG resistance (OR=0.21, p=0.026) and CAL development (OR=0.44, p=0.071). CONCLUSIONS/SIGNIFICANCE: The CCL3L1-CCR5 axis may play an important role in KD pathogenesis. In addition to clinical and laboratory parameters, genetic markers may also predict risk of CAL and resistance to IVIG

Nascentome Analysis Uncovers Futile Protein Synthesis in Escherichia coli

Although co-translational biological processes attract much attention, no general and easy method has been available to detect cellular nascent polypeptide chains, which we propose to call collectively a “nascentome.” We developed a method to selectively detect polypeptide portions of cellular polypeptidyl-tRNAs and used it to study the generality of the quality control reactions that rescue dead-end translation complexes. To detect nascent polypeptides, having their growing ends covalently attached to a tRNA, cellular extracts are separated by SDS-PAGE in two dimensions, first with the peptidyl-tRNA ester bonds preserved and subsequently after their in-gel cleavage. Pulse-labeled nascent polypeptides of Escherichia coli form a characteristic line below the main diagonal line, because each of them had contained a tRNA of nearly uniform size in the first-dimension electrophoresis but not in the second-dimension. The detection of nascent polypeptides, separately from any translation-completed polypeptides or degradation products thereof, allows us to follow their fates to gain deeper insights into protein biogenesis and quality control pathways. It was revealed that polypeptidyl-tRNAs were significantly stabilized in E. coli upon dysfunction of the tmRNA-ArfA ribosome-rescuing system, whose function had only been studied previously using model constructs. Our results suggest that E. coli cells are intrinsically producing aberrant translation products, which are normally eliminated by the ribosome-rescuing mechanisms

Augmented TLR2 Expression on Monocytes in both Human Kawasaki Disease and a Mouse Model of Coronary Arteritis

BACKGROUND: Kawasaki disease (KD) of unknown immunopathogenesis is an acute febrile systemic vasculitis and the leading cause of acquired heart diseases in childhood. To search for a better strategy for the prevention and treatment of KD, this study compared and validated human KD immunopathogenesis in a mouse model of Lactobacillus casei cell wall extract (LCWE)-induced coronary arteritis. METHODS: Recruited subjects fulfilled the criteria of KD and were admitted for intravenous gamma globulin (IVIG) treatment at the Kaohsiung Chang Gung Memorial Hospital from 2001 to 2009. Blood samples from KD patients were collected before and after IVIG treatment, and cardiovascular abnormalities were examined by transthoracic echocardiography. Wild-type male BALB/c mice (4-week-old) were intraperitoneally injected with LCWE (1 mg/mL) to induce coronary arteritis. The induced immune response in mice was examined on days 1, 3, 7, and 14 post injections, and histopathology studies were performed on days 7 and 14. RESULTS: Both human KD patients and LCWE-treated mice developed coronary arteritis, myocarditis, valvulitis, and pericarditis, as well as elevated plasma levels of interleukin (IL)-2, IL-6, IL-10, monocyte chemoattractant protein (MCP)-1, and tumor necrosis factor (TNF)-α in acute phase. Most of these proinflammatory cytokines declined to normal levels in mice, whereas normal levels were achieved in patients only after IVIG treatment, with a few exceptions. Toll-like receptor (TLR)-2, but not TLR4 surface enhancement on circulating CD14+ monocytes, was augmented in KD patients before IVIG treatment and in LCWE-treated mice, which declined in patients after IVIG treatment. CONCLUSION: This result suggests that that not only TLR2 augmentation on CD14+ monocytes might be an inflammatory marker for both human KD patients and LCWE-induced CAL mouse model but also this model is feasible for studying therapeutic strategies of coronary arteritis in human KD by modulating TLR2-mediated immune activation on CD14+ monocytes

Matrix metalloproteinase haplotypes associated with coronary artery aneurysm formation in patients with Kawasaki disease.

Aneurysms of the vascular wall represent a final common pathway for a number of inflammatory processes, including atherosclerosis and idiopathic vasculitis syndromes. Kawasaki disease (KD) is an acute, self-limited vasculitis in children and the leading cause of acquired coronary artery aneurysms. We sought to identify shared molecular mechanisms of aneurysm formation by genotyping eight polymorphisms in matrix metalloproteinase (MMP)-1, 3, 7, 12 and 13 in the gene cluster on Chr.11q22, whose gene products have been implicated in aneurysm formation or are known to have elastase activity. We genotyped 482 US-UK KD patients (aneurysm+: n=111, aneurysm-: n=371) and tested our findings in an independent cohort of 200 Japanese KD patients (aneurysm+: n=58, aneurysm-: n=142). Analysis of the five MMP genes identified modest trends in allele and genotype frequencies for MMP-3 rs3025058 (-/T) and haplotypes containing MMP-3 rs3025058 (-/T) and MMP-12 rs2276109 (A/G) (nominal P=2 to 4 × 10(-5)) that conferred increased risk of aneurysm formation in US-UK subjects. This finding was validated in Japanese subjects and suggests the importance of this locus in aneurysm formation in children with KD. The region encompassing these risk haplotypes is a prime candidate for resequencing to look for rare genetic variation that may influence aneurysm formation

Nitrate regulates floral induction in Arabidopsis, acting independently of light, gibberellin and autonomous pathways

The transition from vegetative growth to reproduction is a major developmental event in plants. To maximise reproductive success, its timing is determined by complex interactions between environmental cues like the photoperiod, temperature and nutrient availability and internal genetic programs. While the photoperiod- and temperature- and gibberellic acid-signalling pathways have been subjected to extensive analysis, little is known about how nutrients regulate floral induction. This is partly because nutrient supply also has large effects on vegetative growth, making it difficult to distinguish primary and secondary influences on flowering. A growth system using glutamine supplementation was established to allow nitrate to be varied without a large effect on amino acid and protein levels, or the rate of growth. Under nitrate-limiting conditions, flowering was more rapid in neutral (12/12) or short (8/16) day conditions in C24, Col-0 and Laer. Low nitrate still accelerated flowering in late-flowering mutants impaired in the photoperiod, temperature, gibberellic acid and autonomous flowering pathways, in the fca co-2 ga1-3 triple mutant and in the ft-7 soc1-1 double mutant, showing that nitrate acts downstream of other known floral induction pathways. Several other abiotic stresses did not trigger flowering in fca co-2 ga1-3, suggesting that nitrate is not acting via general stress pathways. Low nitrate did not further accelerate flowering in long days (16/8) or in 35S::CO lines, and did override the late-flowering phenotype of 35S::FLC lines. We conclude that low nitrate induces flowering via a novel signalling pathway that acts downstream of, but interacts with, the known floral induction pathways