RGS2 determines short-term synaptic plasticity in hippocampal neurons by regulating Gi/o-mediated inhibition of presynaptic Ca2+ channels

RGS2, one of the small members of the regulator of G protein signaling (RGS) family, is highly expressed in brain and regulates G(i/o) as well as G(q)-coupled receptor pathways. RGS2 modulates anxiety, aggression, and blood pressure in mice, suggesting that RGS2 regulates synaptic circuits underlying animal physiology and behavior. How RGS2 in brain influences synaptic activity is unknown. We therefore analyzed the synaptic function of RGS2 in hippocampal neurons by comparing electrophysiological recordings from RGS2 knockout and wild-type mice. Our study provides a general mechanism of the action of the RGS family containing RGS2 by demonstrating that RGS2 increases synaptic vesicle release by downregulating the G(i/o)-mediated presynaptic Ca(2+) channel inhibition and therefore provides an explanation of how regulation of RGS2 expression can modulate the function of neuronal circuits underlying behavior.     

A novel polymorphism in CDC6 is associated with the decline in lung function of ex-smokers in COPD

The effect of smoking cessation on the rate of decline in lung function in patients with advanced stages of chronic obstructive pulmonary disease (COPD) has not been clarified. Saccharomyces cerevisiae cell division cycle 6 homolog (CDC6) protein possesses the pro-apoptotic properties. We tested our hypothesis that the individual susceptibility to rapid decline in lung function despite smoking cessation in patients with advanced stages of COPD is attributed to the genetic variants in the CDC6 gene. We prospectively followed 82 patients (ex-smokers) during 30 months and evaluated the differences among the genotypes in the annual rate of decline in FEV_1.0 (%predicted) with ten single nucleotide polymorphisms (SNPs) in and around the CDC6 gene. We found significant differences in SNP5 (National Center for Biotechnology Information SNP reference: rs2077464), SNP6 (rs13706), SNP7 (rs7217852), and SNP8 (rs9904270) with a gene-dosage effect (ANOVA overall-P = 0.029-0.030). The individual allele of SNP5G, SNP6A, SNP7G, and SNP8T were associated with rapid decline in FEV_1.0 (%predicted) [odds ratio (95% confidence interval) = 2.35 (1.19-4.65), P = 0.014]. The SNP5G/SNP6A/SNP7G/SNP8T haplotype was associated with an increased risk of deterioration of FEV_1.0 (%predicted) (P = 0.017). Importantly, SNP6 caused a change in amino acids in CDC6 protein (Val441Ile), immediately upstream of the caspase-3-dependent cleavage site of CDC6 (Asp442) during apoptosis. These results suggest that CDC6 may be one of the susceptibility genes that contribute to rapid decline in lung function despite smoking cessation in these patients with COPD.     

Novel mouse xenograft models reveal a critical role of CD4+ T cells in the proliferation of EBV-infected T and NK cells

Epstein-Barr virus (EBV), a ubiquitous B-lymphotropic herpesvirus, ectopically infects T or NK cells to cause severe diseases of unknown pathogenesis, including chronic active EBV infection (CAEBV) and EBV-associated hemophagocytic lymphohistiocytosis (EBV-HLH). We developed xenograft models of CAEBV and EBV-HLH by transplanting patients' PBMC to immunodeficient mice of the NOD/Shi-scid/IL-2Rγ(null) strain. In these models, EBV-infected T, NK, or B cells proliferated systemically and reproduced histological characteristics of the two diseases. Analysis of the TCR repertoire expression revealed that identical predominant EBV-infected T-cell clones proliferated in patients and corresponding mice transplanted with their PBMC. Expression of the EBV nuclear antigen 1 (EBNA1), the latent membrane protein 1 (LMP1), and LMP2, but not EBNA2, in the engrafted cells is consistent with the latency II program of EBV gene expression known in CAEBV. High levels of human cytokines, including IL-8, IFN-γ, and RANTES, were detected in the peripheral blood of the model mice, mirroring hypercytokinemia characteristic to both CAEBV and EBV-HLH. Transplantation of individual immunophenotypic subsets isolated from patients' PBMC as well as that of various combinations of these subsets revealed a critical role of CD4+ T cells in the engraftment of EBV-infected T and NK cells. In accordance with this finding, in vivo depletion of CD4+ T cells by the administration of the OKT4 antibody following transplantation of PBMC prevented the engraftment of EBV-infected T and NK cells. This is the first report of animal models of CAEBV and EBV-HLH that are expected to be useful tools in the development of novel therapeutic strategies for the treatment of the diseases.     

Identification of Distinct Ligands for the C-type Lectin Receptors Mincle and Dectin-2 in the Pathogenic Fungus Malassezia

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Highlights? Mincle and Dectin-2 cooperatively recognize Malassezia through distinct ligands ? The Mincle ligands in Malassezia are glucosyl- and mannosylglycolipids ? The Dectin-2 ligand in Malassezia is an O-linked mannobiose-rich glycoprotein ? Cytokine response to the respective ligands was impaired in Mincle^?/? and Dectin-2^?/? DCs     

Linkage disequilibrium analyses of natriuretic peptide precursor B locus reveal risk haplotype conferring high plasma BNP levels

BACKGROUND: Brain natriuretic peptide (BNP) has been widely used for the diagnosis and prognostic evaluation of chronic heart failure (CHF). In the present study, we performed association study of single nucleotide polymorphisms (SNPs) surrounding the natriuretic peptide precursor B (NPPB) gene with plasma BNP levels in 2970 adult Japanese. METHODS AND RESULTS: Association analysis between SNPs of the NPPB gene and plasma BNP revealed significant associations of the 8 SNPs surrounding the entire NPPB gene with plasma BNP levels. For instance, as to SNP rs198389 (T-381C), plasma BNP levels among the three genotypic categories, i.e., 2189 homozygous T-allele carriers (BNP 26.4+/-0.6pg/ml), 697 heterozygous carriers (35.0+/-1.1pg/ml), and 52 homozygous C-allele carriers (46.0+/-4.1pg/ml) indicated a co-dominant effect of the minor C-allele on elevating plasma BNP levels (P<0.0001). Linkage disequilibrium (LD) analysis among the 8 SNPs revealed that the region consisted of two, 5' major and 3' minor, LD blocks. Haplotype-based association analysis demonstrated that plasma BNP levels were associated closely with the haplotypes-1 and -2 of the major LD block. CONCLUSION: These results suggest that genetic variation at the primary locus NPPB gene, represented by definition of risk haplotypes, may be an important determinant of plasma BNP levels.     

IL-1α induces thrombopoiesis through megakaryocyte rupture in response to acute platelet needs

Intravital visualization of thrombopoiesis revealed that formation of proplatelets, which are cytoplasmic protrusions in bone marrow megakaryocytes (MKs), is dominant in the steady state. However, it was unclear whether this is the only path to platelet biogenesis. We have identified an alternative MK rupture, which entails rapid cytoplasmic fragmentation and release of much larger numbers of platelets, primarily into blood vessels, which is morphologically and temporally different than typical FasL-induced apoptosis. Serum levels of the inflammatory cytokine IL-1α were acutely elevated after platelet loss or administration of an inflammatory stimulus to mice, whereas the MK-regulator thrombopoietin (TPO) was not elevated. Moreover, IL-1α administration rapidly induced MK rupture–dependent thrombopoiesis and increased platelet counts. IL-1α–IL-1R1 signaling activated caspase-3, which reduced plasma membrane stability and appeared to inhibit regulated tubulin expression and proplatelet formation, and ultimately led to MK rupture. Collectively, it appears the balance between TPO and IL-1α determines the MK cellular programming for thrombopoiesis in response to acute and chronic platelet needs.     

Neuronal Categorization and Discrimination of Social Behaviors in Primate Prefrontal Cortex

It has been implied that primates have an ability to categorize social behaviors between other individuals for the execution of adequate social-interactions. Since the lateral prefrontal cortex (LPFC) is involved in both the categorization and the processing of social information, the primate LPFC may be involved in the categorization of social behaviors. To test this hypothesis, we examined neuronal activity in the LPFC of monkeys during presentations of two types of movies of social behaviors (grooming, mounting) and movies of plural monkeys without any eye- or body-contacts between them (no-contacts movies). Although the monkeys were not required to categorize and discriminate the movies in this task, a subset of neurons sampled from the LPFC showed a significantly different activity during the presentation of a specific type of social behaviors in comparison with the others. These neurons categorized social behaviors at the population level and, at the individual neuron level, the majority of the neurons discriminated each movie within the same category of social behaviors. Our findings suggest that a fraction of LPFC neurons process categorical and discriminative information of social behaviors, thereby contributing to the adaptation to social environments.     

Association of the PIK3C2G gene polymorphisms with type 2 DM in a Japanese population

The associations of five SNPs (SNPs1-5: A-5468G, A-3333G, C-1794T, C437T and T9148C) of the class II phosphoinositide 3-kinase γ-subunit (PIK3C2G) gene with type 2 diabetes were examined using a population of the Takahata Study (n (M/W): 2930 (1328/1602); age: 63.3 ± 10.2 years), a Japanese community-based study. Quantitative association study of the SNPs with HbA1c levels showed significant association for SNPs 2 and 4 (p = 0.018 and 0.004, respectively). A case-control association study of SNP 4 with diabetes by multiple logistic regression analysis showed a significant association of the genotype TT of the SNP with an odds ratio of 2.21 (p = 0.001) independently of age, gender and BMI. In the NGT subjects, serum fasting insulin levels in the at-risk genotype group of SNP 4 were significantly lower than those in the others (TT, TC, and CC, 4.9 ± 2.6, 5.4 ± 3.0, and 5.6 ± 3.4 μU/ml, respectively; p = 0.029).     

A monoclonal antibody against insect CALNUC recognizes the prooncoprotein EWS specifically in mammalian cells. Immunohistochemical and biochemical studies of the antigen in rat tissues

A monoclonal antibody against insect CALNUC was shown to recognize an 85-kDa nuclear protein specifically in mammalian cells. Amino acid sequencing of the protein purified from rat liver revealed it to be EWS, a prooncoprotein for Ewing sarcomas and related tumors. Using the antibody, distribution of EWS was studied in rat tissues fixed with 4% paraformaldehyde by immunohistochemical methods. On thaw-fixed cryosections or those of perfusion-fixed tissues, almost all cell nuclei showed the specific staining. In immersion-fixed tissues, the staining unexpectedly disappeared in particular tissues (kidney cortex, liver, etc.), although it was recovered by autoclaving the cryosections. Western blotting also demonstrated the ubiquitous expression of EWS in the tissues. In extracts from the liver, the 85-kDa band rapidly disappeared in a Ca(2+)-dependent manner, but never in the testis. The antigen was very labile in kidney homogenates even without Ca2+. Biochemical studies with digoxigenin-labeled EWS showed that the Ca(2+)-dependent disappearance was associated with upward mobility shifts of EWS. These suggested that EWS was ubiquitously expressed in rat tissues, and that the antigen was masked in particular tissues during the immersion fixation.     

Immunocytochemical demonstration of the secretory dynamics of zymogenic contents in rat gastric gland processed by high-pressure freezing/freeze substitution, with special references to phospholipase A2 and phospholipase Cγ1

High-pressure freezing/freeze substitution followed by Lowicryl K4M embedding provided an excellent morphology and antigenicity of the gastric glands, as well as the intraluminal fluid contents. Taking advantage of this, we histochemically investigated the secretory dynamics of the zymogenic contents in rat gastric gland, with special references to phospholipase A(2) (PLA(2)) and phospholipase Cgamma1 (PLCgamma1). The combination of immunogold labeling and KMnO4-uranyl acetate-lead citrate staining for zymogenic contents clearly demonstrated the rapid diffusion of PLA(2) molecules from the exocytosed zymogenic contents into the mucinous contents in gastric glandular lumens. In contrast, the exocytosed PLCgamma1 molecules remained within the zymogenic contents in the glandular lumens. These findings indicated the distinction between the exocytosed PLA(2) and PLCgamma1 in their diffusion rate. In addition, the mucinous contents surrounding the exocytosed zymogenic contents were intensely labeled with Griffonia simplicifolia II lectin which specifically recognizes the mucin of mucous neck cells. Interestingly, some of the PLA(2) immunolabeling on the mucinous contents was associated with the apical membranes of gastric epithelial cells, especially that of parietal cells. The secretory dynamics of the zymogenic contents in rat gastric glands, including their interaction with the mucinous contents are discussed.