Nitric oxide-induced calcium release via ryanodine receptors regulates neuronal function

Mobilization of intracellular Ca(2+) stores regulates a multitude of cellular functions, but the role of intracellular Ca(2+) release via the ryanodine receptor (RyR) in the brain remains incompletely understood. We found that nitric oxide (NO) directly activates RyRs, which induce Ca(2+) release from intracellular stores of central neurons, and thereby promote prolonged Ca(2+) signalling in the brain. Reversible S-nitrosylation of type 1 RyR (RyR1) triggers this Ca(2+) release. NO-induced Ca(2+) release (NICR) is evoked by type 1 NO synthase-dependent NO production during neural firing, and is essential for cerebellar synaptic plasticity. NO production has also been implicated in pathological conditions including ischaemic brain injury, and our results suggest that NICR is involved in NO-induced neuronal cell death. These findings suggest that NICR via RyR1 plays a regulatory role in the physiological and pathophysiological functions of the brain.     

Novel loci for adiponectin levels and their influence on type 2 diabetes and metabolic traits: a multi-ethnic meta-analysis of 45,891 individuals

Circulating levels of adiponectin, a hormone produced predominantly by adipocytes, are highly heritable and are inversely associated with type 2 diabetes mellitus (T2D) and other metabolic traits. We conducted a meta-analysis of genome-wide association studies in 39,883 individuals of European ancestry to identify genes associated with metabolic disease. We identified 8 novel loci associated with adiponectin levels and confirmed 2 previously reported loci (P = 4.5×10⁻⁸–1.2×10⁻⁴³). Using a novel method to combine data across ethnicities (N = 4,232 African Americans, N = 1,776 Asians, and N = 29,347 Europeans), we identified two additional novel loci. Expression analyses of 436 human adipocyte samples revealed that mRNA levels of 18 genes at candidate regions were associated with adiponectin concentrations after accounting for multiple testing (p<3×10⁻⁴). We next developed a multi-SNP genotypic risk score to test the association of adiponectin decreasing risk alleles on metabolic traits and diseases using consortia-level meta-analytic data. This risk score was associated with increased risk of T2D (p = 4.3×10⁻³, n = 22,044), increased triglycerides (p = 2.6×10⁻¹⁴, n = 93,440), increased waist-to-hip ratio (p = 1.8×10⁻⁵, n = 77,167), increased glucose two hours post oral glucose tolerance testing (p = 4.4×10⁻³, n = 15,234), increased fasting insulin (p = 0.015, n = 48,238), but with lower in HDL-cholesterol concentrations (p = 4.5×10⁻¹³, n = 96,748) and decreased BMI (p = 1.4×10⁻⁴, n = 121,335). These findings identify novel genetic determinants of adiponectin levels, which, taken together, influence risk of T2D and markers of insulin resistance.     

Rat mutations cvd and hob with cerebellar malformations map to chromosome 2.

In this paper, we executed genome mapping and comparative mapping analyses for cvd and hob, autosomal recessive mutations with cerebellar vermis defect and cerebellar dysplasia in the rat. For the linkage analysis, we produced three sets of backcross progeny, (ACI x CVD)F(1) and (F344 x CVD)F(1) females crossed to a cvd homozygous male rat, and (HOB x WKY)F(1) males crossed to hob homozygous female rats. Analysis of the segregation patterns of simple sequence length polymorphism (SSLP) markers scanning the whole rat genome allowed the mapping of these autosomal recessive mutations to rat Chromosome (Chr) 2. The most likely gene order is D2Mgh12 - D2Rat86 - D2Mit15 - D2Rat185 - cvd - D2Rat66 - D2Mgh13, and D2Mit18 - Fga -D2Mit14 - D2Rat16 - hob - D2Mgh13. Crossing test between a proven cvd heterozygous and a hob heterozygous rats demonstrated their allelism. Furthermore, comparative mapping indicated the cvd locus corresponds to mouse chromosome 3 and a strong candidate gene Unc5h3, a causative gene for the rostral cerebellar malformation mouse, was implicated.     

Phosphodiesterase 8B gene variants are associated with serum TSH levels and thyroid function

Thyroid-stimulating hormone (TSH) controls thyroid growth and hormone secretion through binding to its G protein-coupled receptor (TSHR) and production of cyclic AMP (cAMP). Serum TSH is a sensitive indicator of thyroid function, and overt abnormalities in thyroid function lead to common endocrine disorders affecting approximately 10% of individuals over a life span. By genotyping 362,129 SNPs in 4,300 Sardinians, we identified a strong association (p = 1.3 x 10(-11)) between alleles of rs4704397 and circulating TSH levels; each additional copy of the minor A allele was associated with an increase of 0.13 muIU/ml in TSH. The single-nucleotide polymorphism (SNP) is located in intron 1 of PDE8B, encoding a high-affinity cAMP-specific phosphodiesterase. The association was replicated in 4,158 individuals, including additional Sardinians and two genetically distant cohorts from Tuscany and the Old Order Amish (overall p value = 1.9 x 10(-20)). In addition to association of TSH levels with SNPs in PDE8B, our genome scan provided evidence for association with PDE10A and several biologically interesting candidates in a focused analysis of 24 genes. In particular, we found evidence for association of TSH levels with SNPs in the THRB (rs1505287, p = 7.3 x 10(-5)), GNAQ (rs10512065, p = 2.0 x 10(-4)), TG (rs2252696, p = 2.2 x 10(-3)), POU1F1 (rs1976324, p = 3.9 x 10(-3)), PDE4D (rs27178, p = 8.3 x 10(-3)), and TSHR (rs4903957, p = 8.6 x 10(-3)) loci. Overall, the results suggest a primary effect of PDE8B variants on cAMP levels in the thyroid. This would affect production of T4 and T3 and feedback to alter TSH release by the pituitary. PDE8B may thus provide a candidate target for the treatment of thyroid dysfunction.     

Staphylococcus aureus surface protein SasG contributes to intercellular autoaggregation of Staphylococcus aureus

Staphylococcus aureus surface protein G (SasG) is one of cell surface proteins with cell-wall sorting motif. The sasG mutant showed significantly reduced cell aggregation and biofilm formation. SasG is comprised of variable A domain and multiple tandem repeats of B domain, native-PAGE and in vitro formaldehyde cross-linking experiments revealed that the recombinant protein of the A domain showed homo-oligomerization as an octamer, but B domain did not. This study shows that SasG-A domain contributes to intercellular autoaggregation by homo-oligomerization, and that may facilitate the adherence to host-tissues in the infection of S. aureus.     

Impaired autophagy by soluble endoglin,under physiological hypoxia in early pregnant period,is involved in poor placentation in preeclampsia

In early pregnancy, trophoblasts and the fetus experience hypoxic and low-nutrient conditions; nevertheless, trophoblasts invade the uterine myometrium up to one third of its depth and migrate along the lumina of spiral arterioles, replacing the maternal endothelial lining. Here, we showed that autophagy, an intracellular bulk degradation system, occurred in extravillous trophoblast (EVT) cells under hypoxia in vitro and in vivo. An enhancement of autophagy was observed in EVTs in early placental tissues, which suffer from physiological hypoxia. The invasion and vascular remodeling under hypoxia were significantly reduced in autophagy-deficient EVT cells compared with wild-type EVT cells. Interestingly, soluble endoglin (sENG), which increased in sera in preeclamptic cases, suppressed EVT invasion by inhibiting autophagy. The sENG-inhibited EVT invasion was recovered by TGFB1 treatment in a dose-dependent manner. A high dose of sENG inhibited the vascular construction by EVT cells and human umbilical vein endothelial cells (HUVECs), meanwhile a low dose of sENG inhibited the replacement of HUVECs by EVT cells. A protein selectively degraded by autophagy, SQSTM1, accumulated in EVT cells in preeclamptic placental biopsy samples showing impaired autophagy. This is the first report showing that impaired autophagy in EVT contributes to the pathophysiology of preeclampsia.     

Identifying sequence determinants of reduction potentials of metalloproteins

The reduction potential of an electron transfer protein is one of its most important functional characteristics. Although the type of redox site and the protein fold are the major determinants of the reduction potential of a redox-active protein, its amino acid sequence may tune the reduction potential as well. Thus, homologous proteins can often be divided into different classes, with each class characterized by a biological function and a reduction potential. Site-specific mutagenesis of the sequence determinants of the differences in the reduction potential between classes should change the reduction potential of a protein in one class to that of the other class. Here, a procedure is presented that combines energetic and bioinformatic analysis of homologous proteins to identify sequence determinants that are also good candidates for site-specific mutations, using the [4Fe–4S] ferredoxins and the [4Fe–4S] high-potential iron–sulfur proteins as examples. This procedure is designed to guide site-specific mutations or more computationally expensive studies, such as molecular dynamics simulations. To make the procedure more accessible to the general scientific community, it is being implemented into CHARMMing, a Web-based portal, with a library of density functional theory results for the redox site that are used in the setting up of Poisson–Boltzmann continuum electrostatics calculations for the protein energetics.     

Quantitation using a stable isotope dilution assay (SIDA) and thresholds of taste-active pyroglutamyl decapeptide ethyl esters (PGDPEs) in sake

A stable isotope dilution assay (SIDA) for two taste-active pyroglutamyl decapeptide ethyl esters (PGDPE1; (pGlu)LFGPNVNPWCOOC₂H₅, PGDPE2; (pGlu)LFNPSTNPWCOOC₂H₅) in sake was developed using deuterated isotopes and high-resolution mass spectrometry. Recognition thresholds of PGDPEs in sake were estimated as 3.8 μg/L for PGDPE1 and 8.1 μg/L for PGDPE2, evaluated using 11 student panelists aged in their twenties. Quantitated concentrations in 18 commercial sake samples ranged from 0 to 27 μg/L for PGDPE1 and from 0 to 202 μg/L for PGDPE2. The maximum levels of PGDPE1 and PGDPE2 in the sake samples were approximately 8 and 25 times higher than the estimated recognition thresholds, respectively. The results indicated that PGDPEs may play significant sensory roles in the sake. The level of PGDPEs in unpasteurized sake samples decreased during storage for 50 days at 6 °C, suggesting PGDPEs may be enzymatically decomposed.     

A familial case of visceral toxocariasis due to consumption of raw bovine liver

We present 3 adult cases of visceral toxocariasis from the same family, who each consumed thin slices of raw bovine liver weekly, and developed eosinophilia and multiple small lesions in their livers and lungs. Serological examinations using the larval excretory–secretory product of Toxocara canis strongly indicated infection with Toxocara species larvae. The patients responded well to treatment with albendazole. Ingestion of raw liver from paratenic animals is considered to be a common transmission route of human toxocariasis, especially in adults.