Receptor dimerization dynamics as a regulatory valve for plasticity of type I interferon signaling

Type I interferons (IFNs) activate differential cellular responses through a shared cell surface receptor composed of the two subunits, IFNAR1 and IFNAR2. We propose here a mechanistic model for how IFN receptor plasticity is regulated on the level of receptor dimerization. Quantitative single-molecule imaging of receptor assembly in the plasma membrane of living cells clearly identified IFN-induced dimerization of IFNAR1 and IFNAR2. The negative feedback regulator ubiquitin-specific protease 18 (USP18) potently interferes with the recruitment of IFNAR1 into the ternary complex, probably by impeding complex stabilization related to the associated Janus kinases. Thus, the responsiveness to IFNα2 is potently down-regulated after the first wave of gene induction, while IFNβ, due to its ∼100-fold higher binding affinity, is still able to efficiently recruit IFNAR1. Consistent with functional data, this novel regulatory mechanism at the level of receptor assembly explains how signaling by IFNβ is maintained over longer times compared with IFNα2 as a temporally encoded cause of functional receptor plasticity.     

Chimpanzees’ constructional praxis (Pan paniscus, P. troglodytes)

This study investigated chimpanzees spontaneous spatial constructions with objects and especially their ability to repeat inter-object spatial relations, which is basic to understanding spatial relations at a higher level than perception or recognition. Subjects were six chimpanzees—four chimpanzees and two bonobos—aged 6–21 years, all raised in a human environment from an early age. Only minor species differences, but considerable individual differences were found. The effect of different object samples was assessed through a comparison with a previous study. A common overall chimpanzee pattern was also found. Chimpanzees repeated different types of inter-object spatial relations such as insertion (I), or vertical (V), or next-to (H) relations. However chimpanzees repeated I or V relations with more advanced procedures than when repeating H relations. Moreover, chimpanzees never repeated combined HV relations. Compared with children, chimpanzees showed a specific difficulty in repeating H relations. Repeating H relations is crucial for representing and understanding multiple reciprocal spatial relations between detached elements and for coordinating independent positions in space. Therefore, the chimpanzees difficulty indicates a fundamental difference in constructive space in comparison to humans. The findings are discussed in relation to issues of spatial cognition and tool use.     

Social cognition in anorexia nervosa: evidence of preserved theory of mind and impaired emotional functioning

Background

The findings of the few studies that have to date investigated the way in which individuals with Anorexia Nervosa (AN) navigate their social environment are somewhat contradictory. We undertook this study to shed new light on the social-cognitive profile of patients with AN, analysing Theory of Mind and emotional functioning. Starting from previous evidence on the role of the amygdala in the neurobiology of AN and in the social cognition, we hypothesise preserved Theory of Mind and impaired emotional functioning in patients with AN.

Methodology

Thirty women diagnosed with AN and thirty-two women matched for education and age were involved in the study. Theory of Mind and emotional functioning were assessed with a set of validated experimental tasks. A measure of perceived social support was also used to test the correlations between this dimension and the social-cognitive profile of AN patients.

Principal Findings

The performance of patients with AN is significantly worse than that of healthy controls on tasks assessing emotional functioning, whereas patients’ performance is comparable to that of healthy controls on the Theory of Mind task. Correlation analyses showed no relationship between scores on any of the social-cognition tasks and either age of onset or duration of illness. A correlation between social support and emotional functioning was found. This latter result seems to suggest a potential role of social support in the treatment and recovery of AN.

Conclusions

The pattern of results followed the experimental hypothesis. They may be useful to help us better understand the social-cognitive profile of patients with AN and to contribute to the development of effective interventions based on the ways in which patients with AN actually perceive their social environment.     

Probiotics modulate intestinal expression of nuclear receptor and provide counter-regulatory signals to inflammation-driven adipose tissue activation

Background

Adipocytes from mesenteric white adipose tissue amplify the inflammatory response and participate in inflammation-driven immune dysfunction in Crohn''s disease by releasing proinflammatory mediators. Peroxisome proliferator-activated receptors (PPAR)-α and -γ, pregnane x receptor (PXR), farnesoid x receptor (FXR) and liver x-receptor (LXR) are ligand-activated nuclear receptor that provide counter-regulatory signals to dysregulated immunity and modulates adipose tissue.

Aims

To investigate the expression and function of nuclear receptors in intestinal and adipose tissues in a rodent model of colitis and mesenteric fat from Crohn''s patients and to investigate their modulation by probiotics.

Methods

Colitis was induced by TNBS administration. Mice were administered vehicle or VSL#3, daily for 10 days. Abdominal fat explants obtained at surgery from five Crohn''s disease patients and five patients with colon cancer were cultured with VSL#3 medium.

Results

Probiotic administration attenuated development of signs and symptoms of colitis, reduced colonic expression of TNFα, IL-6 and IFNγ and reserved colonic downregulation of PPARγ, PXR and FXR caused by TNBS. Mesenteric fat depots isolated from TNBS-treated animals had increased expression of inflammatory mediators along with PPARγ, FXR, leptin and adiponectin. These changes were prevented by VSL#3. Creeping fat and mesenteric adipose tissue from Crohn''s patients showed a differential expression of PPARγ and FXR with both tissue expressing high levels of leptin. Exposure of these tissues to VSL#3 medium abrogates leptin release.

Conclusions

Mesenteric adipose tissue from rodent colitis and Crohn''s disease is metabolically active and shows inflammation-driven regulation of PPARγ, FXR and leptin. Probiotics correct the inflammation-driven metabolic dysfunction.     

Dynamics of Vaginal Bacterial Communities in Women Developing Bacterial Vaginosis, Candidiasis, or No Infection, Analyzed by PCR-Denaturing Gradient Gel Electrophoresis and Real-Time PCR

The microbial flora of the vagina plays a major role in preventing genital infections, including bacterial vaginosis (BV) and candidiasis (CA). An integrated approach based on PCR-denaturing gradient gel electrophoresis (PCR-DGGE) and real-time PCR was used to study the structure and dynamics of bacterial communities in vaginal fluids of healthy women and patients developing BV and CA. Universal eubacterial primers and Lactobacillus genus-specific primers, both targeted at 16S rRNA genes, were used in DGGE and real-time PCR analysis, respectively. The DGGE profiles revealed that the vaginal flora was dominated by Lactobacillus species under healthy conditions, whereas several potentially pathogenic bacteria were present in the flora of women with BV. Lactobacilli were the predominant bacterial population in the vagina for patients affected by CA, but changes in the composition of Lactobacillus species were observed. Real-time PCR analysis allowed the quantitative estimation of variations in lactobacilli associated with BV and CA diseases. A statistically significant decrease in the relative abundance of lactobacilli was found in vaginal fluids of patients with BV compared to the relative abundance of lactobacilli in the vaginal fluids of healthy women and patients with CA.     

Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes

Research in autophagy continues to accelerate,(1) and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.(2,3) There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.     

Sensitivity of Saccharomyces cerevisiae vegetative cells and spores to antimicrobial compounds

The sensitivity of Saccharomyces cerevisiae spores and vegetative cells to various antimicrobial compounds was compared. Sulphur dioxide, benzoic acid, potassium sorbate, salicylic acid, nystatin, actidione and pimaricin were tested. Generally, the Saccharomyces spores were more resistant than the corresponding vegetative cells. It was also observed that this greater resistance shown by the spores varied with the antimicrobial compound used. Only potassium sorbate was not selective and killed both vegetative cells and spores at about the same rate.     

MeCP2 Affects Skeletal Muscle Growth and Morphology through Non Cell-Autonomous Mechanisms

Rett syndrome (RTT) is an autism spectrum disorder mainly caused by mutations in the X-linked MECP2 gene and affecting roughly 1 out of 10.000 born girls. Symptoms range in severity and include stereotypical movement, lack of spoken language, seizures, ataxia and severe intellectual disability. Notably, muscle tone is generally abnormal in RTT girls and women and the Mecp2-null mouse model constitutively reflects this disease feature. We hypothesized that MeCP2 in muscle might physiologically contribute to its development and/or homeostasis, and conversely its defects in RTT might alter the tissue integrity or function. We show here that a disorganized architecture, with hypotrophic fibres and tissue fibrosis, characterizes skeletal muscles retrieved from Mecp2-null mice. Alterations of the IGF-1/Akt/mTOR pathway accompany the muscle phenotype. A conditional mouse model selectively depleted of Mecp2 in skeletal muscles is characterized by healthy muscles that are morphologically and molecularly indistinguishable from those of wild-type mice raising the possibility that hypotonia in RTT is mainly, if not exclusively, mediated by non-cell autonomous effects. Our results suggest that defects in paracrine/endocrine signaling and, in particular, in the GH/IGF axis appear as the major cause of the observed muscular defects. Remarkably, this is the first study describing the selective deletion of Mecp2 outside the brain. Similar future studies will permit to unambiguously define the direct impact of MeCP2 on tissue dysfunctions.     

Beta(1)/beta(2)/beta(3)-adrenoceptor knockout mice are obese and cold-sensitive but have normal lipolytic responses to fasting

Catecholamines are viewed as major stimulants of diet- and cold-induced thermogenesis and of fasting-induced lipolysis, through the β-adrenoceptors (β₁/β₂/β₃). To test this hypothesis, we generated β₁/β₂/β₃-adrenoceptor triple knockout (TKO) mice and compared them to wild type animals. TKO mice exhibited normophagic obesity and cold-intolerance. Their brown fat had impaired morphology and lacked responses to cold of uncoupling protein-1 expression. In contrast, TKO mice had higher circulating levels of free fatty acids and glycerol at basal and fasted states, suggesting enhanced lipolysis. Hence, β-adrenergic signalling is essential for the resistance to obesity and cold, but not for the lipolytic response to fasting.