The multivalent PDZ domain-containing protein PDZK1 regulates transport activity of renal urate-anion exchanger URAT1 via its C terminus

The urate-anion exchanger URAT1 is a member of the organic anion transporter (OAT) family that regulates blood urate level in humans and is targeted by uricosuric and antiuricosuric agents. URAT1 is expressed only in the kidney, where it is thought to participate in tubular urate reabsorption. We found that the multivalent PDZ (PSD-95, Drosophila discs-large protein, Zonula occludens protein 1) domain-containing protein, PDZK1 interacts with URAT1 in a yeast two-hybrid screen. Such an interaction requires the PDZ motif of URAT1 in its extreme intracellular C-terminal region and the first, second, and fourth PDZ domains of PDZK1 as identified by yeast two-hybrid assay, in vitro binding assay and surface plasmon resonance analysis (K(D) = 1.97-514 nM). Coimmunoprecipitation studies revealed that the wild-type URAT1, but not its mutant lacking the PDZ-motif, directly interacts with PDZK1. Colocalization of URAT1 and PDZK1 was observed at the apical membrane of renal proximal tubular cells. The association of URAT1 with PDZK1 enhanced urate transport activities in HEK293 cells (1.4-fold), and the deletion of the URAT1 C-terminal PDZ motif abolished this effect. The augmentation of the transport activity was accompanied by a significant increase in the V(max) of urate transport via URAT1 and was associated with the increased surface expression level of URAT1 protein from HEK293 cells stably expressing URAT1 transfected with PDZK1. Taken together, the present study indicates the novel role of PDZK1 in regulating the functional activity of URAT1-mediated urate transport in the apical membrane of renal proximal tubules.     

Determination of anti-Aspergillus activity of antifungal agents based on the dynamic growth rate of a single hypha

The dynamic growth rate of a single hypha of Aspergillus niger was analysed using an automatic system. A colony of A. niger was in contact with saline, saline containing an antifungal agent, and flushing saline, in sequence. The growth rate of a test hypha selected arbitrarily from the colony responded dynamically to the antifungal agent. The minimum concentration that caused the complete inhibition of hyphal growth was defined as the minimum inhibitory concentration (MIC). The MIC values obtained were compared with those determined by conventional methods based on increasing rate of colony diameter or dry matter weight.     

The Light Skin Allele of SLC24A5 in South Asians and Europeans Shares Identity by Descent

Skin pigmentation is one of the most variable phenotypic traits in humans. A non-synonymous substitution (rs1426654) in the third exon of SLC24A5 accounts for lighter skin in Europeans but not in East Asians. A previous genome-wide association study carried out in a heterogeneous sample of UK immigrants of South Asian descent suggested that this gene also contributes significantly to skin pigmentation variation among South Asians. In the present study, we have quantitatively assessed skin pigmentation for a largely homogeneous cohort of 1228 individuals from the Southern region of the Indian subcontinent. Our data confirm significant association of rs1426654 SNP with skin pigmentation, explaining about 27% of total phenotypic variation in the cohort studied. Our extensive survey of the polymorphism in 1573 individuals from 54 ethnic populations across the Indian subcontinent reveals wide presence of the derived-A allele, although the frequencies vary substantially among populations. We also show that the geospatial pattern of this allele is complex, but most importantly, reflects strong influence of language, geography and demographic history of the populations. Sequencing 11.74 kb of SLC24A5 in 95 individuals worldwide reveals that the rs1426654-A alleles in South Asian and West Eurasian populations are monophyletic and occur on the background of a common haplotype that is characterized by low genetic diversity. We date the coalescence of the light skin associated allele at 22–28 KYA. Both our sequence and genome-wide genotype data confirm that this gene has been a target for positive selection among Europeans. However, the latter also shows additional evidence of selection in populations of the Middle East, Central Asia, Pakistan and North India but not in South India.     

Wnt3a upregulates transforming growth factor-β-stimulated VEGF synthesis in osteoblasts

It is recognized that Wnt3a affects bone metabolism via the canonical Wnt/β-catenin signalling pathway. We have previously shown that transforming growth factor-β (TGF-β) stimulates the synthesis of vascular endothelial growth factor (VEGF) via p44/p42 mitogen-activated protein (MAP) kinase, stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK) and p38 MAP kinase in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of Wnt3a on TGF-β-stimulated VEGF synthesis in these cells. Wnt3a, which alone had little effect on the VEGF levels, significantly enhanced the TGF-β-stimulated VEGF release. Lithium chloride and SB216763, inhibitors of glycogen synthase kinase 3β, markedly amplified the TGF-β-stimulated VEGF release. Wnt3a failed to affect the TGF-β-induced phosphorylation of Smad2, p44/p42 MAP kinase, p38 MAP kinase or SAPK/JNK. Wnt3a and lithium chloride strengthened the VEGF mRNA expression induced by TGF-β. These results strongly suggest that Wnt3a upregulates VEGF synthesis stimulated by TGF-β via activation of the canonical pathway in osteoblasts.     

Identification of Seroreactive Proteins of Leptospira interrogans Serovar Copenhageni Using a High-Density Protein Microarray Approach

Background

Leptospirosis is a widespread zoonotic disease worldwide. The lack of an adequate laboratory test is a major barrier for diagnosis, especially during the early stages of illness, when antibiotic therapy is most effective. Therefore, there is a critical need for an efficient diagnostic test for this life threatening disease.

Methodology

In order to identify new targets that could be used as diagnostic makers for leptopirosis, we constructed a protein microarray chip comprising 61% of Leptospira interrogans proteome and investigated the IgG response from 274 individuals, including 80 acute-phase, 80 convalescent-phase patients and 114 healthy control subjects from regions with endemic, high endemic, and no endemic transmission of leptospirosis. A nitrocellulose line blot assay was performed to validate the accuracy of the protein microarray results.

Principal findings

We found 16 antigens that can discriminate between acute cases and healthy individuals from a region with high endemic transmission of leptospirosis, and 18 antigens that distinguish convalescent cases. Some of the antigens identified in this study, such as LipL32, the non-identical domains of the Lig proteins, GroEL, and Loa22 are already known to be recognized by sera from human patients, thus serving as proof-of-concept for the serodiagnostic antigen discovery approach. Several novel antigens were identified, including the hypothetical protein LIC10215 which showed good sensitivity and specificity rates for both acute- and convalescent-phase patients.

Conclusions

Our study is the first large-scale evaluation of immunodominant antigens associated with naturally acquired leptospiral infection, and novel as well as known serodiagnostic leptospiral antigens that are recognized by antibodies in the sera of leptospirosis cases were identified. The novel antigens identified here may have potential use in both the development of new tests and the improvement of currently available assays for diagnosing this neglected tropical disease. Further research is needed to assess the utility of these antigens in more deployable diagnostic platforms.     

Effect of antithrombin III on glycoprotein Ib/IX/V activation in human platelets: Suppression of thromboxane A(2) generation

We have previously shown that ristocetin, an activator of glycoprotein Ib/IX/V, induces release of soluble CD40 (sCD40) ligand via thromboxane (TX) A(2) production from human platelets. In the present study, we investigated the effect of antithrombin-III (AT-III), an anticoagulant, on the ristocetin-induced glycoprotein Ib/IX/V activation in human platelets. AT-III inhibited ristocetin-stimulated platelet aggregation. The ristocetin-induced production of 11-dehydro-TXB(2), a stable metabolite of TXA(2), and the release of sCD40 ligand were suppressed by AT-III. AT-III also reduced the ristocetin-stimulated secretion of platelet-derived growth factor (PDGF)-AB. AT-III failed to affect U46619-, a TXA(2) receptor agonist, induced levels of p38 mitogen-activated protein kinase phosphorylation or sCD40 ligand release. AT-III reduced the binding of SZ2, a monoclonal antibody to the sulfated sequence in the α-chain of glycoprotein Ib, to the ristocetin-stimulated platelets. These results strongly suggest that AT-III reduced ristocetin-stimulated release of sCD40 ligand due to inhibiting TXA(2) production in human platelets.     

Changes in Permeability of Brush Border Membrane Vesicles from Spodoptera littoralis Midgut Induced by Insecticidal Crystal Proteins from Bacillus thuringiensis

Bacillus thuringiensis insecticidal crystal proteins (ICPs) are thought to induce pore formation in midgut cell membranes of susceptible insects. Cry1Ca, which is significantly active in Spodoptera littoralis, made brush border membrane vesicles permeable to KCl (osmotic swelling was monitored by the light scattering technique); the marginally active ICPs Cry1Aa, Cry1Ab, and Cry1Ac did not.     

Antibody Profiling by Proteome Microarray with Multiplex Isotype Detection Reveals Overlap between Human and Aotus nancymaae Controlled Malaria Infections

The development of vaccines against malaria and serodiagnostic tests for detecting recent exposure requires tools for antigen discovery and suitable animal models. The protein microarray is a high‐throughput, sample sparing technique, with applications in infectious disease research, clinical diagnostics, epidemiology, and vaccine development. We recently demonstrated Qdot‐based indirect immunofluorescence together with portable optical imager ArrayCAM using single isotype detection could replicate data using the conventional laser confocal scanner system. We developed a multiplexing protocol for simultaneous detection of IgG, IgA, and IgM and compared samples from a controlled human malaria infection model with those from controlled malaria infections of Aotus nancymaae, a widely used non‐human primate model of human malaria. IgG profiles showed the highest concordance in number of reactive antigens; thus, of the 139 antigens recognized by human IgG antibody, 111 were also recognized by Aotus monkeys. Interestingly, IgA profiles were largely non‐overlapping. Finally, on the path toward wider deployment of the portable platform, we show excellent correlations between array data obtained in five independent laboratories around the United States using the multiplexing protocol (R²: 0.60–0.92). This study supports the use of this platform for wider deployment, particularly in endemic areas where such a tool will have the greatest impact on global human health.     

Homologous recombination-mediated knock-in targeting of the MET1a gene for a maintenance DNA methyltransferase reproducibly reveals dosage-dependent spatiotemporal gene expression in rice

Although homologous recombination-promoted knock-in targeting to monitor the expression of a gene by fusing a reporter gene with its promoter is routine practice in mice, gene targeting to modify endogenous genes in flowering plants remains in its infancy. In the knock-in targeting, the junction sequence between a reporter gene and an endogenous target promoter can be designed properly, and transgenic plants carrying an identical and desired knock-in allele can be repeatedly obtained. By employing a reproducible gene-targeting procedure with positive–negative selection in rice, we were able to obtain fertile transgenic knock-in plants with the promoterless GUS reporter gene encoding β-glucuronidase fused with the endogenous promoter of MET1a , one of two rice MET1 genes encoding a maintenance DNA methyltransferase. All of the primary (T₀) transgenic knock-in plants obtained were found to carry only one copy of GUS , with the anticipated structure in the heterozygous condition, and no ectopic events associated with gene targeting could be detected. We showed the reproducible, dosage-dependent and spatiotemporal expression of GUS in the selfed progenies of independently isolated knock-in targeted plants. The results in knock-in targeted plants contrast sharply with the results in transgenic plants with the MET1a promoter -fused GUS reporter gene integrated randomly in the genome: clear interindividual variation of GUS expression was observed among independently obtained plants bearing the randomly integrated transgenes. As our homologous recombination-mediated gene-targeting strategy with positive–negative selection is, in principle, applicable to modify any endogenous gene, knock-in targeting would facilitate basic and applied plant research.     

The More the Merrier: Recent Hybridization and Polyploidy in Cardamine

This article describes the use of cytogenomic and molecular approaches to explore the origin and evolution of Cardamine schulzii, a textbook example of a recent allopolyploid, in its ∼110-year history of human-induced hybridization and allopolyploidy in the Swiss Alps. Triploids are typically viewed as bridges between diploids and tetraploids but rarely as parental genomes of high-level hybrids and polyploids. The genome of the triploid semifertile hybrid Cardamine × insueta (2n = 24, RRA) was shown to combine the parental genomes of two diploid (2n = 2x = 16) species, Cardamine amara (AA) and Cardamine rivularis (RR). These parental genomes have remained structurally stable within the triploid genome over the >100 years since its origin. Furthermore, we provide compelling evidence that the alleged recent polyploid C. schulzii is not an autohexaploid derivative of C. × insueta. Instead, at least two hybridization events involving C. × insueta and the hypotetraploid Cardamine pratensis (PPPP, 2n = 4x−2 = 30) have resulted in the origin of the trigenomic hypopentaploid (2n = 5x−2 = 38, PPRRA) and hypohexaploid (2n = 6x−2 = 46, PPPPRA). These data show that the semifertile triploid hybrid can promote a merger of three different genomes and demonstrate how important it is to reexamine the routinely repeated textbook examples using modern techniques.