Combined analysis of three genome-wide association studies on vWF and FVIII plasma levels

<p>Abstract</p> <p>Background</p> <p>Elevated levels of factor VIII (FVIII) and von Willebrand Factor (vWF) are well-established risk factors for cardiovascular diseases, in particular venous thrombosis. Although high, the heritability of these traits is poorly explained by the genetic factors known so far. The aim of this work was to identify novel single nucleotide polymorphisms (SNPs) that could influence the variability of these traits.</p> <p>Methods</p> <p>Three independent genome-wide association studies for vWF plasma levels and FVIII activity were conducted and their results were combined into a meta-analysis totalling 1,624 subjects.</p> <p>Results</p> <p>No single nucleotide polymorphism (SNP) reached the study-wide significance level of 1.12 × 10^-7that corresponds to the Bonferroni correction for the number of tested SNPs. Nevertheless, the recently discovered association of <it>STXBP5</it>, <it>STX2</it>, <it>TC2N </it>and <it>CLEC4M </it>genes with vWF levels and that of <it>SCARA5 </it>and STAB2 genes with FVIII levels were confirmed in this meta-analysis. Besides, among the fifteen novel SNPs showing promising association at p < 10^-5with either vWF or FVIII levels in the meta-analysis, one located in <it>ACCN1 </it>gene also showed weak association (<it>P </it>= 0.0056) with venous thrombosis in a sample of 1,946 cases and 1,228 controls.</p> <p>Conclusions</p> <p>This study has generated new knowledge on genomic regions deserving further investigations in the search for genetic factors influencing vWF and FVIII plasma levels, some potentially implicated in VT, as well as providing some supporting evidence of previously identified genes.</p

The Interaction between the First Transmembrane Domain and the Thumb of ASIC1a Is Critical for Its N-Glycosylation and Trafficking

Acid-sensing ion channel-1a (ASIC1a), the primary proton receptor in the brain, contributes to multiple diseases including stroke, epilepsy and multiple sclerosis. Thus, a better understanding of its biogenesis will provide important insights into the regulation of ASIC1a in diseases. Interestingly, ASIC1a contains a large, yet well organized ectodomain, which suggests the hypothesis that correct formation of domain-domain interactions at the extracellular side is a key regulatory step for ASIC1a maturation and trafficking. We tested this hypothesis here by focusing on the interaction between the first transmembrane domain (TM1) and the thumb of ASIC1a, an interaction known to be critical in channel gating. We mutated Tyr71 and Trp287, two key residues involved in the TM1-thumb interaction in mouse ASIC1a, and found that both Y71G and W287G decreased synaptic targeting and surface expression of ASIC1a. These defects were likely due to altered folding; both mutants showed increased resistance to tryptic cleavage, suggesting a change in conformation. Moreover, both mutants lacked the maturation of N-linked glycans through mid to late Golgi. These data suggest that disrupting the interaction between TM1 and thumb alters ASIC1a folding, impedes its glycosylation and reduces its trafficking. Moreover, reducing the culture temperature, an approach commonly used to facilitate protein folding, increased ASIC1a glycosylation, surface expression, current density and slowed the rate of desensitization. These results suggest that correct folding of extracellular ectodomain plays a critical role in ASIC1a biogenesis and function

A Constitutional Translocation t(1;17)(p36.2;q11.2) in a Neuroblastoma Patient Disrupts the Human NBPF1 and ACCN1 Genes

The human 1p36 region is deleted in many different types of tumors, and so it probably harbors one or more tumor suppressor genes. In a Belgian neuroblastoma patient, a constitutional balanced translocation t(1;17)(p36.2;q11.2) may have led to the development of the tumor by disrupting or activating a gene. Here, we report the cloning of both translocation breakpoints and the identification of a novel gene that is disrupted by this translocation. This gene, named NBPF1 for Neuroblastoma BreakPoint Family member 1, belongs to a recently described gene family encoding highly similar proteins, the functions of which are unknown. The translocation truncates NBPF1 and gives rise to two chimeric transcripts of NBPF1 sequences fused to sequences derived from chromosome 17. On chromosome 17, the translocation disrupts one of the isoforms of ACCN1, a potential glioma tumor suppressor gene. Expression of the NBPF family in neuroblastoma cell lines is highly variable, but it is decreased in cell lines that have a deletion of chromosome 1p. More importantly, expression profiling of the NBPF1 gene showed that its expression is significantly lower in cell lines with heterozygous NBPF1 loss than in cell lines with a normal 1p chromosome. Meta-analysis of the expression of NBPF and ACCN1 in neuroblastoma tumors indicates a role for the NBPF genes and for ACCN1 in tumor aggressiveness. Additionally, DLD1 cells with inducible NBPF1 expression showed a marked decrease of clonal growth in a soft agar assay. The disruption of both NBPF1 and ACCN1 genes in this neuroblastoma patient indicates that these genes might suppress development of neuroblastoma and possibly other tumor types

Upregulation of the constitutively expressed HSC70 by KLF4

Krüppel-like factor 4 (KLF4) is a transcription factor that is abundantly expressed in various organisms from bacteria to mammals. It has been demonstrated that KLF4 regulates the expression of a wide range of genes. Analysis of KLF4 target genes reveals its diverse regulatory functions in cell growth, proliferation, differentiation, embryogenesis, and inflammation. However, the regulation of the expression of inducible heat shock protein 70 (HSP72) and heat shock cognate 70 (HSP73) by KLF4 is not defined. In our previous study, a complementary deoxyribonucleic acid microarray assay showed that KLF4 overexpression led to dramatic upregulation of HSP73 messenger ribonucleic acid (mRNA) in murine C2C12 myoblast cells, suggesting that HSP73 is a potential target gene regulated by KLF4. The effect of KLF4 on the expression of HSP72 and HSP73 was further examined by reverse transcriptase polymerase chain reaction and Western blot in KLF4-overexpressing or KLF4-deficient cells. The results showed the upregulation of the HSP73 constitutive expression by KLF4 overexpression in both C2C12 cells and murine RAW264.7 macrophages; in response to heat stress, however, few changes were observed in the levels of HSP73 by KLF4 overexpression. In addition, knockdown of endogenous KLF4 expression by morpholino antisense oligonucleotides significantly decreased both HSP73 mRNA and protein levels under normal conditions. Conversely, KLF4 had no effect on the expression of HSP72. Taken together, these findings suggest an important role for KLF4 as a novel regulator of the constitutive expression of HSP73

CIB1 is a regulator of pathological cardiac hypertrophy

Hypertrophic heart disease is a leading health problem facing the Western world. Here we identified the small EF-hand domain-containing protein CIB1 (Ca2+ and integrin binding protein 1) in a screen for novel regulators of cardiomyocyte hypertrophy. Yeast two-hybrid screening for CIB1 interacting partners identified a related EF-hand domain-containing protein calcineurin B, the regulatory subunit of the pro-hypertrophic protein phosphatase calcineurin. CIB1 largely localizes to the sarcolemma in mouse and human myocardium, where it anchors calcineurin to control its activation in coordination with the L-type Ca2+ channel. CIB1 protein levels and membrane association were enhanced in cardiac pathological hypertrophy, but not in physiological hypertrophy. Consistent with these observations, mice lacking Cib1 show a dramatic reduction in myocardial hypertrophy, fibrosis, cardiac dysfunction, and calcineurin-NFAT activity following pressure overload, while the degree of physiologic hypertrophy after swimming was not altered. Transgenic mice with inducible and cardiac-specific overexpression of CIB1 showed enhanced cardiac hypertrophy in response to pressure overload or calcineurin signaling. Moreover, mice lacking the Ppp3cb gene showed no enhancement in cardiac hypertrophy associated wit