De Novo Mutations in GNAO1, Encoding a Gαo Subunit of Heterotrimeric G Proteins, Cause Epileptic Encephalopathy

Heterotrimeric G proteins, composed of α, β, and γ subunits, can transduce a variety of signals from seven-transmembrane-type receptors to intracellular effectors. By whole-exome sequencing and subsequent mutation screening, we identified de novo heterozygous mutations in GNAO1, which encodes a Gαo subunit of heterotrimeric G proteins, in four individuals with epileptic encephalopathy. Two of the affected individuals also showed involuntary movements. Somatic mosaicism (approximately 35% to 50% of cells, distributed across multiple cell types, harbored the mutation) was shown in one individual. By mapping the mutation onto three-dimensional models of the Gα subunit in three different complexed states, we found that the three mutants (c.521A>G [p.Asp174Gly], c.836T>A [p.Ile279Asn], and c.572_592del [p.Thr191_Phe197del]) are predicted to destabilize the Gα subunit fold. A fourth mutant (c.607G>A), in which the Gly203 residue located within the highly conserved switch II region is substituted to Arg, is predicted to impair GTP binding and/or activation of downstream effectors, although the p.Gly203Arg substitution might not interfere with Gα binding to G-protein-coupled receptors. Transient-expression experiments suggested that localization to the plasma membrane was variably impaired in the three putatively destabilized mutants. Electrophysiological analysis showed that Gαo-mediated inhibition of calcium currents by norepinephrine tended to be lower in three of the four Gαo mutants. These data suggest that aberrant Gαo signaling can cause multiple neurodevelopmental phenotypes, including epileptic encephalopathy and involuntary movements

Neuropsychiatric Disorder Associated with Group G Streptococcus Infection

Immune-mediated central nervous system manifestations of group A β-hemolytic Streptococcus (GABHS) infection include Sydenham’s chorea, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection (PANDAS)—which includes tic and obsessive compulsive disorders—and a variety of neurobehavioral disorders. We report a case of Streptococcus dysgalactiae subspecies equisimilis (group G Streptococcus) (GGS) infection associated with involuntary movements, complex tics, and emotional lability in an 11-year-old Japanese girl. Serum IgM and IgG antibodies to lysoganglioside were positive, and she responded rapidly to intravenous immunoglobulin treatment. Neuropsychiatric disorder associated with GGS infection was ultimately diagnosed. The present findings suggest that neuropsychiatric disorders can result from GGS infection and that the pathogenic mechanism is similar to that of GABHS infection. Future large-scale studies should examine the relation between GGS infection and onset of neuropsychiatric disorder

Effect of a single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin on immune function in Male NC/Nga mice

Exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces immunosuppression in humans and animals. However, the effect of TCDD on Th2-type immune responses such as allergic reactions has been unclear. Using NC/Nga mice that developed atopic dermatitis-like skin lesions with marked elevation in plasma of total IgE when bred under conventional conditions, we investigated the effects of a single oral dose of TCDD on immune responses. NC/Nga mice received a single oral dose (0 or 20 microg/kg body weight) of TCDD. On day 7, treatment with TCDD alone decreased the cellularity of thymus. However, treatment with TCDD modified the cellularity of spleens and mesenteric lymph nodes (MLNs) but not of the thymus on day 28. When NC/Nga mice received ip immunization with OVA and alum on the same day as the TCDD treatment (0, 5, or 20 microg/kg body weight), TCDD markedly suppressed the concentrations of Th2-type cytokines (e.g., IL-4 and IL-5) in culture supernatants of spleen cells, whereas IFN-gamma production significantly increased. TCDD exposure reduced anti-OVA and total IgE antibody titers in plasma and did not induce the development of atopic dermatitis-like lesions in the pinnae or dorsal skin of NC/Nga mice. These results suggest that in NC/Nga mice, exposure to TCDD may impair the induction of Th2-type immune responses

Effect of statins on the serum soluble form of receptor for advanced glycation end-products and its association with coronary atherosclerosis in patients with angina pectoris

Background: Advanced glycation end-products (AGEs) and their receptor (RAGE) play an important role in the pathogenesis of diabetic vascular complications. Recently, soluble form of RAGE (sRAGE) has been identified in mice and humans. Statins have been reported to increase serum sRAGE levels. However, whether modulation of circulating sRAGE levels has a beneficial effect on the progression of atherosclerosis is unknown. Methods: We reviewed 91 patients who had undergone percutaneous coronary intervention for angina pectoris. Coronary atherosclerosis in non-culprit lesions in the target vessel was evaluated, using virtual histology intravascular ultrasound, and serum levels of AGEs and sRAGE were measured, at baseline and after 8 months of statin therapy. Results: Statins had no effects on serum AGEs levels; however, serum levels of sRAGE were significantly higher at the 8-month follow-up. A significant decrease in external elastic membrane (EEM) volume (−1.6%, p = 0.005) was observed, whereas a decrease in plaque volume did not reach statistical significance (−1.9%, p = 0.16). Univariate regression analyses showed that the percentage changes in serum sRAGE were negatively correlated with those in EEM volume (r = −0.198, p = 0.06) and plaque volume (r = −0.247, p = 0.02). Multivariate regression analysis showed that an increase in serum sRAGE level was an independent predictor of atheroma regression after statin therapy (β = −0.290, p = 0.006). Conclusions: Statin therapy increased serum sRAGE levels, and this increase was associated with negative vessel remodeling and atheroma regression in the coronary artery

Understanding the Molecular Basis for Differences in Responses of Fish Estrogen Receptor Subtypes to Environmental Estrogens

Exposure to endocrine disrupting chemicals (EDCs) can elicit adverse effects on development, sexual differentiation, and reproduction in fish. Teleost species exhibit at least three subtypes of estrogen receptor (ESR), ESR1, ESR2a, and ESR2b; thus, estrogenic signaling pathways are complex. We applied in vitro reporter gene assays for ESRs in five fish species to investigate the ESR subtype-specificity for better understanding the signaling pathway of estrogenic EDCs. Responses to bisphenol A, 4-nonylphenol, and <i>o,p</i>′-DDT varied among ESR subtypes, and the response pattern of ESRs was basically common among the different fish species. Using a computational in silico docking model and through assays quantifying transactivation of the LBD (using GAL-LBD fusion proteins and chimera proteins for the ESR2s), we found that the LBD of the different ESR subtypes generally plays a key role in conferring responsiveness of the ESR subtypes to EDCs. These results also indicate that responses of ESR2s to EDCs cannot necessarily be predicted from the LBD sequence alone, and an additional region is required for full transactivation of these receptors. Our data thus provide advancing understanding on receptor functioning for both basic and applied research

Differing Species Responsiveness of Estrogenic Contaminants in Fish Is Conferred by the Ligand Binding Domain of the Estrogen Receptor

Exposure to estrogenic endocrine disrupting chemicals (EDCs) induces a range of adverse effects, notably on reproduction and reproductive development. These responses are mediated via estrogen receptors (ERs). Different species of fish may show differences in their responsiveness to environmental estrogens but there is very limited understanding on the underlying mechanisms accounting for these differences. We used custom developed <i>in vitro</i> ERα reporter gene assays for nine fish species to analyze the ligand- and species-specificity for 12 environmental estrogens. Transcriptonal activities mediated by estradiol-17β (E2) were similar to only a 3-fold difference in ERα sensitivity between species. Diethylstilbestrol was the most potent estrogen (∼10-fold that of E2) in transactivating the fish ERαs, whereas equilin was about 1 order of magnitude less potent in all species compared to E2. Responses of the different fish ERαs to weaker environmental estrogens varied, and for some considerably. Medaka, stickleback, bluegill and guppy showed higher sensitivities to nonylphenol, octylphenol, bisphenol A and the DDT-metabolites compared with cyprinid ERαs. Triclosan had little or no transactivation of the fish ERαs. By constructing ERα chimeras in which the AF-containing domains were swapped between various fish species with contrasting responsiveness and subsequent exposure to different environmental estrogens. Our <i>in vitro</i> data indicate that the LBD plays a significant role in accounting for ligand sensitivity of ERα in different species. The differences seen in responsiveness to different estrogenic chemicals between species indicate environmental risk assessment for estrogens cannot necessarily be predicted for all fish by simply examining receptor activation for a few model fish species