A novel mutation in EROS (CYBC1) causes chronic granulomatous disease

Chronic Granulomatous Disease (CGD) is an inborn error of immunity characterised by opportunistic infection and sterile granulomatous inflammation. CGD is caused by a failure of reactive oxygen species (ROS) production by the phagocyte NADPH oxidase. Mutations in the genes encoding phagocyte NADPH oxidase subunits cause CGD. We and others have described a novel form of CGD (CGD5) secondary to lack of EROS (CYBC1), a highly selective chaperone for gp91phox. EROS-deficient cells express minimal levels of gp91phox and its binding partner p22phox, but EROS also controls the expression of other proteins such as P2X7. The full nature of CGD5 is currently unknown. We describe a homozygous frameshift mutation in CYBC1 leading to CGD. Individuals who are heterozygous for this mutation are found in South Asian populations (allele frequency = 0.00006545), thus it is not a private mutation. Therefore, it is likely to be the underlying cause of other cases of CGD.

Identification of novel proteins involved in P2X7-mediated signaling cascades

High concentration of extracellular ATP acts as a danger signal that is sensed by the P2X7 receptor (P2X7R). This ATP-gated ion channel has been shown to induce multiple metabotropic events such as changes in plasma membrane composition and morphology, ectodomain shedding, activation of lipases, kinases, and transcription factors as well as cytokine release. The specific signaling pathways and molecular mechanisms remain largely obscure. Using an unbiased genome-scale CRISPR/Cas9 screening approach in a murine T cell line, Ryoden et al. (2022, 2020) identified three proteins involved in P2X7 regulation and signaling: Essential for Reactive Oxygen Species (EROS) is essential for P2X7 folding and maturation, and Xk and Vsp13a are required for P2X7-mediated phosphatidyl serine exposure and cell lysis. They further provide evidence for an interaction of Xk and Vsp13a at the plasma membrane and confirm the role of Xk in ATP-induced cytolysis in primary CD25⁺CD4⁺ T cells from Xk^-/- mice.

Conformational ensemble of the full-length SARS-CoV-2 nucleocapsid (N) protein based on molecular simulations and SAXS data

The nucleocapsid protein of the SARS-CoV-2 virus comprises two RNA-binding domains and three regions that are intrinsically disordered. While the structures of the RNA-binding domains have been solved using protein crystallography and NMR, current knowledge of the conformations of the full-length nucleocapsid protein is rather limited. To fill in this knowledge gap, we combined coarse-grained molecular simulations with data from small-angle X-ray scattering (SAXS) experiments using the ensemble refinement of SAXS (EROS) method. Our results show that the dimer of the full-length nucleocapsid protein exhibits large conformational fluctuations with its radius of gyration ranging from about 4 to 8 nm. The RNA-binding domains do not make direct contacts. The disordered region that links these two domains comprises a hydrophobic α-helix which makes frequent and nonspecific contacts with the RNA-binding domains. Each of the intrinsically disordered regions adopts conformations that are locally compact, yet on average, much more extended than Gaussian chains of equivalent lengths. We offer a detailed picture of the conformational ensemble of the nucleocapsid protein dimer under near-physiological conditions, which will be important for understanding the nucleocapsid assembly process.

Spatiotemporal dynamics of attentional orienting and reorienting revealed by fast optical imaging in occipital and parietal cortices

The mechanisms of visuospatial attention are mediated by two distinct fronto-parietal networks: a bilateral dorsal network (DAN), involved in the voluntary orientation of visuospatial attention, and a ventral network (VAN), lateralized to the right hemisphere, involved in the reorienting of attention to unexpected, but relevant, stimuli. The present study consisted of two aims: 1) to characterize the spatio-temporal dynamics of attention and 2) to examine the predictive interactions between and within the two attention systems along with visual areas, by using fast optical imaging combined with Granger causality. Data were collected from young healthy participants performing a discrimination task in a Posner-like paradigm. Functional analyses revealed bilateral dorsal parietal (i.e. dorsal regions included in the DAN) and visual recruitment during orienting, highlighting a recursive predictive interplay between specific dorsal parietal regions and visual cortex. Moreover, we found that both attention networks are active during reorienting, together with visual cortex, highlighting a mutual interaction among dorsal and visual areas, which, in turn, predicts subsequent ventral activity. For attentional reorienting our findings indicate that dorsal and visual areas encode disengagement of attention from the attended location and trigger reorientation to the unexpected location. Ventral network activity could instead reflect post-perceptual maintenance of the internal model to generate and keep updated task-related expectations.

Functional connectivity of the frontotemporal network in preattentive detection of abstract changes: Perturbs and observes with transcranial magnetic stimulation and event-related optical signal

Current theories of automatic or preattentive change detection suggest a regularity or prediction violation mechanism involving functional connectivity between the inferior frontal cortex (IFC) and the superior temporal cortex (STC). By disrupting the IFC function with transcranial magnetic stimulation (TMS) and recording the later STC mismatch response with event-related optical signal (EROS), previous study demonstrated a causal IFC-to-STC functional connection in detecting a pitch or physical change. However, physical change detection can be achieved by memory comparison of the physical features and may not necessarily involve regularity/rule extraction and prediction. The current study investigated the IFC-STC functional connectivity in detecting rule violation (i.e., an abstract change). Frequent standard tone pairs with a constant relative pitch difference, but varying pitches, were presented to establish a pitch interval rule. This abstract rule was violated by deviants with reduced relative pitch intervals. The EROS STC mismatch response to the deviants was abolished by the TMS applied at the IFC 80 ms after deviance onset, but preserved in the spatial (TMS on vertex), auditory (TMS sound), and temporal (200 ms after deviance onset) control conditions. These results demonstrate the IFC-STC connection in preattentive abstract change detection and support the regularity or prediction violation account.

Recent advances in chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited defect of phagocyte function due to defective NADPH oxidase. Patients with CGD are not able to effectively clear the infections because of the defect in the phagocyte production of oxygen free radicals and are prone to recurrent bacterial and fungal infections. Inflammatory complications are also noted in CGD such as colitis, non-infective granulomas causing gastrointestinal or urinary tract obstruction, hemophagocytic lymphohistiocytosis, and arthritis. Studies on toll-like receptor pathways and neutrophil extracellular traps in CGD have shed light on the role of NADPH oxidase in the innate immunity and pathogenesis of infections in CGD. Some reports also indicate a reduction of memory B cells and defective production of functional antibodies in CGD. Though the exact mechanisms for non-infective inflammatory complications in CGD are not yet clear, studies on efferocytosis and defective autophagy with inflammasome activation have made a substantial contribution to our understanding of the pathogenesis of inflammation in CGD. We also discuss the clinical and molecular features of p40^phox defects and a newer genetic defect, EROS. Clinical phenotypes of X-linked carriers of CYBB are also discussed.

Inhibition of the antioxidant activity of catalase and superoxide dismutase from Fusarium verticillioides exposed to a Jacquinia macrocarpa antifungal fraction

The aim of this study was to investigate the in vitro effect of an antifungal fraction obtained from Jacquinia macrocarpa plant (JmAF) in the generation of reactive oxygen species (ROS) and the activity of the catalase (CAT) and superoxide dismutase (SOD) enzymes from Fusarium verticillioides, as well as their influence in the viability of the fungus spores. The compounds present in the JmAF were determined by gas chromatography/quadrupole time-of-flight mass spectrometry (GC/QTOF-MS). The effect of the exposition to JmAF on the generation of ROS, as well as in the CAT and SOD activities in F. verticillioides, was determined. The main compounds detected were γ-sitosterol, stephamiersine, betulinol and oleic acid. JmAF showed very high ability in inhibiting the spore viability of F. verticillioides, and their capacity to cause oxidative stress by induction of ROS production. JmAF induced the highest ROS concentration and also inhibited CAT and SOD activities. The results obtained in this study indicate that JmAF is worthy of being considered for the fight against phytopathogenic fungi.

Structures of Dynamic Protein Complexes: Hybrid Techniques to Study MAP Kinase Complexes and the ESCRT System

The integration of complementary molecular methods (including X-ray crystallography, NMR spectroscopy, small angle X-ray/neutron scattering, and computational techniques) is frequently required to obtain a comprehensive understanding of dynamic macromolecular complexes. In particular, these techniques are critical for studying intrinsically disordered protein regions (IDRs) or intrinsically disordered proteins (IDPs) that are part of large protein:protein complexes. Here, we explain how to prepare IDP samples suitable for study using NMR spectroscopy, and describe a novel SAXS modeling method (ensemble refinement of SAXS; EROS) that integrates the results from complementary methods, including crystal structures and NMR chemical shift perturbations, among others, to accurately model SAXS data and describe ensemble structures of dynamic macromolecular complexes.

Spatially explicit Schistosoma infection risk in eastern Africa using Bayesian geostatistical modelling

Schistosomiasis remains one of the most prevalent parasitic diseases in the tropics and subtropics, but current statistics are outdated due to demographic and ecological transformations and ongoing control efforts. Reliable risk estimates are important to plan and evaluate interventions in a spatially explicit and cost-effective manner. We analysed a large ensemble of georeferenced survey data derived from an open-access neglected tropical diseases database to create smooth empirical prevalence maps for Schistosoma mansoni and Schistosoma haematobium for a total of 13 countries of eastern Africa. Bayesian geostatistical models based on climatic and other environmental data were used to account for potential spatial clustering in spatially structured exposures. Geostatistical variable selection was employed to reduce the set of covariates. Alignment factors were implemented to combine surveys on different age-groups and to acquire separate estimates for individuals aged ≤20 years and entire communities. Prevalence estimates were combined with population statistics to obtain country-specific numbers of Schistosoma infections. We estimate that 122 million individuals in eastern Africa are currently infected with either S. mansoni, or S. haematobium, or both species concurrently. Country-specific population-adjusted prevalence estimates range between 12.9% (Uganda) and 34.5% (Mozambique) for S. mansoni and between 11.9% (Djibouti) and 40.9% (Mozambique) for S. haematobium. Our models revealed that infection risk in Burundi, Eritrea, Ethiopia, Kenya, Rwanda, Somalia and Sudan might be considerably higher than previously reported, while in Mozambique and Tanzania, the risk might be lower than current estimates suggest. Our empirical, large-scale, high-resolution infection risk estimates for S. mansoni and S. haematobium in eastern Africa can guide future control interventions and provide a benchmark for subsequent monitoring and evaluation activities.

Concurrent application of TMS and near-infrared optical imaging: methodological considerations and potential artifacts

The simultaneous application of transcranial magnetic stimulation (TMS) with non-invasive neuroimaging provides a powerful method for investigating functional connectivity in the human brain and the causal relationships between areas in distributed brain networks. TMS has been combined with numerous neuroimaging techniques including, electroencephalography (EEG), functional magnetic resonance imaging (fMRI), and positron emission tomography (PET). Recent work has also demonstrated the feasibility and utility of combining TMS with non-invasive near-infrared optical imaging techniques, functional near-infrared spectroscopy (fNIRS) and the event-related optical signal (EROS). Simultaneous TMS and optical imaging affords a number of advantages over other neuroimaging methods but also involves a unique set of methodological challenges and considerations. This paper describes the methodology of concurrently performing optical imaging during the administration of TMS, focusing on experimental design, potential artifacts, and approaches to controlling for these artifacts.