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There are suspected links between air pollution and atopic dermatitis, but the mechanism has remained unclear. Yamamoto and colleagues demonstrate that air pollutants trigger activation of the aryl hydrocarbon receptor in the skin, hyperinnervation and an itch-scratch cycle that leads to atopic dermatitis. Atopic dermatitis is increasing worldwide in correlation with air pollution. Various organic components of pollutants activate the transcription factor AhR (aryl hydrocarbon receptor). Through the use of AhR-CA mice, whose keratinocytes express constitutively active AhR and that develop atopic-dermatitis-like phenotypes, we identified Artn as a keratinocyte-specific AhR target gene whose product (the neurotrophic factor artemin) was responsible for epidermal hyper-innervation that led to hypersensitivity to pruritus. The activation of AhR via air pollutants induced expression of artemin, alloknesis, epidermal hyper-innervation and inflammation. AhR activation and ARTN expression were positively correlated in the epidermis of patients with atopic dermatitis. Thus, AhR in keratinocytes senses environmental stimuli and elicits an atopic-dermatitis pathology. We propose a mechanism of air-pollution-induced atopic dermatitis via activation of AhR.

Amyloid-β oligomers may cause cognitive deficits in Alzheimer’s disease by impairing neuronal NMDA-type glutamate receptors, whose function is regulated by the receptor tyrosine kinase EphB2. Here we show that amyloid-β oligomers bind to the fibronectin repeats domain of EphB2 and trigger EphB2 degradation in the proteasome. To determine the pathogenic importance of EphB2 depletions in Alzheimer’s disease and related models, we used lentiviral constructs to reduce or increase neuronal expression of EphB2 in memory centres of the mouse brain. In nontransgenic mice, knockdown of EphB2 mediated by short hairpin RNA reduced NMDA receptor currents and impaired long-term potentiation in the dentate gyrus, which are important for memory formation. Increasing EphB2 expression in the dentate gyrus of human amyloid precursor protein transgenic mice reversed deficits in NMDA receptor-dependent long-term potentiation and memory impairments. Thus, depletion of EphB2 is critical in amyloid-β-induced neuronal dysfunction. Increasing EphB2 levels or function could be beneficial in Alzheimer’s disease. EphB2: a factor in memory loss Association studies have previously implicated the EphB2 receptor in Alzheimer's disease. As a member of a large family of tyrosine kinase receptors that regulate diverse biological functions, its role in the condition remained unknown. Cissé et al . now show that amyloid-β oligomers interact with EphB2 and trigger its degradation. EphB2 regulates NMDA-type glutamate receptors, and its depletion in normal mice reduces NMDAR currents and impairs long-term potentiation, both of which are important for memory formation. Increasing EphB2 levels in a mouse model of Alzheimer's disease improves memory, suggesting that increasing EphB2 levels or function could be of therapeutic value in Alzheimer's disease. It is shown that amyloid-β oligomers interact with the receptor tyrosine kinase EphB2 and trigger its degradation. EphB2 regulates NMDA-type glutamate receptors and its depletion in normal mice reduces NMDA receptor currents and impairs long-term potentiation, both of which are important for memory formation. Increasing EphB2 levels in a mouse model of Alzheimer's disease improves memory.

This report describes the isolation and in vitro expansion of human colon stem cells from normal tissues. Cells with high levels of the membrane receptor EPHB2 are shown to have characteristics of intestinal stem cells, and the authors optimize culture conditions that allow their in vitro expansion as multipotent cells capable of differentiation into several intestinal lineages. Here we describe the isolation of stem cells of the human colonic epithelium. Differential cell surface abundance of ephrin type-B receptor 2 (EPHB2) allows the purification of different cell types from human colon mucosa biopsies. The highest EPHB2 surface levels correspond to epithelial colonic cells with the longest telomeres and elevated expression of intestinal stem cell (ISC) marker genes. Moreover, using culturing conditions that recreate the ISC niche, a substantial proportion of EPHB2-high cells can be expanded in vitro as an undifferentiated and multipotent population.

Cause for anxiety Many individuals experience traumatic events, but some people seem relatively unaffected whereas others develop post-traumatic stress disorder. Now, work in mice has identified a possible cause for this variation between individuals. During stress, the serine protease neuropsin elicits plasticity in the amygdala by regulating EphB2/NMDA receptor interactions, inducing expression of the fear-related gene Fkbp5v . Mice lacking neuropsin do not exhibit the same dynamic plasticity in response to stress. These results underscore the importance of molecular pathways in the manifestation of complex behaviours such as anxiety, and point to Eph and NMDA receptors as possible therapeutic targets. A minority of individuals experiencing traumatic events develop anxiety disorders. The reason for the lack of correspondence between the prevalence of exposure to psychological trauma and the development of anxiety is unknown. Extracellular proteolysis contributes to fear-associated responses by facilitating neuronal plasticity at the neuron–matrix interface 1 , 2 , 3 , 4 . Here we show in mice that the serine protease neuropsin is critical for stress-related plasticity in the amygdala by regulating the dynamics of the EphB2–NMDA-receptor interaction, the expression of Fkbp5 and anxiety-like behaviour. Stress results in neuropsin-dependent cleavage of EphB2 in the amygdala causing dissociation of EphB2 from the NR1 subunit of the NMDA receptor and promoting membrane turnover of EphB2 receptors. Dynamic EphB2–NR1 interaction enhances NMDA receptor current, induces Fkbp5 gene expression and enhances behavioural signatures of anxiety. On stress, neuropsin-deficient mice do not show EphB2 cleavage and its dissociation from NR1 resulting in a static EphB2–NR1 interaction, attenuated induction of the Fkbp5 gene and low anxiety. The behavioural response to stress can be restored by intra-amygdala injection of neuropsin into neuropsin-deficient mice and disrupted by the injection of either anti-EphB2 antibodies or silencing the Fkbp5 gene in the amygdala of wild-type mice. Our findings establish a novel neuronal pathway linking stress-induced proteolysis of EphB2 in the amygdala to anxiety.

Purpose Recent studies have increasingly linked Ephrin receptor B2 (EPHB2) to cancer progression. However, comprehensive investigations into the immunological roles and prognostic significance of EPHB2 across various cancers remain lacking. Methods We employed various databases and bioinformatics tools to investigate the impact of EPHB2 on prognosis, immune infiltration, genome instability, and response to immunotherapy. Validation of the correlation between EPHB2 expression and M2 macrophages included analyses using bulk and single-cell transcriptomic datasets, spatial transcriptomics, and multi-fluorescence staining. Moreover, we performed cMap web tool to screen for EPHB2-targeted compounds and assessed their potential through molecular docking and dynamics simulations. Additionally, in vitro validation using lung adenocarcinoma (LUAD) cell lines was conducted to confirm the bioinformatics predictions about EPHB2. Results EPHB2 dysregulation was observed across multiple cancer types, where it demonstrated significant diagnostic and prognostic value. Gene Set Enrichment Analysis (GSEA) indicated that EPHB2 is involved in enhancing cellular proliferation, invasiveness of cancer cells, and modulation of the anti-cancer immune response. Furthermore, it is emerged as a pan-cancer marker for M2 macrophage infiltration, supported by integrated analyses of transcriptomics and multiple fluorescence staining. In LUAD cells, knockdown of EPHB2 expression led to a decrease in both cell proliferation and migratory activity. Conclusion EPHB2 expression may serve as a pivotal indicator of M2 macrophage infiltration, offering vital insights into tumor dynamics and progression across various cancers, including lung adenocarcinoma, highlighting its significant prognostic and therapeutic potential for further exploration.

Aberrant regulation of the Wnt/β-catenin pathway has an important role during the onset and progression of colorectal cancer, with over 90% of cases of sporadic colon cancer featuring mutations in APC or β-catenin. However, it has remained a point of controversy whether these mutations are sufficient to activate the pathway or require additional upstream signals. Here we show that colorectal tumours express elevated levels of Wnt3 and Evi/Wls/GPR177. We found that in colon cancer cells, even in the presence of mutations in APC or β-catenin, downstream signalling remains responsive to Wnt ligands and receptor proximal signalling. Furthermore, we demonstrate that truncated APC proteins bind β-catenin and key components of the destruction complex. These results indicate that cells with mutations in APC or β-catenin depend on Wnt ligands and their secretion for a sufficient level of β-catenin signalling, which potentially opens new avenues for therapeutic interventions by targeting Wnt secretion via Evi/Wls. Activating mutations in the Wnt signalling pathway are associated with colon cancer. Here the authors show that tumour cells carrying mutations in APC and β-catenin are still regulated by Wnt ligands, suggesting that Wnt secretion and receptor signalling remains important to control downstream signalling.

Many brain diseases lead to a reduction in the number of functional neurons and it would be of value to be able to increase the number of neurons in the affected brain areas. In this study, we examined whether we can promote neural stem cells to produce mature neurons and whether an increase in the mature neurons can affect cognitive performance. We detected that the EphB2 receptor is localized in immature basolateral amygdala (BLA) neurons. We therefore aimed to increase the level of EphB2 activity in neural stem cells (NSCs) in the BLA and examine the effects on the production of mature neurons and cognition. Toward that end, we utilized a photoactivatable EphB2 construct (optoEphB2) to increase EphB2 forward signaling in NSCs in the BLA. We revealed that the activation of optoEphB2 in NSCs in the BLA increased the level of immature and mature neurons in the BLA. We further found that activation of optoEphB2 in BLA NSCs enhanced auditory, but not contextual, long-term fear memory formation. Impairing EphB2 forward signaling did not affect the level of immature and mature neurons in the BLA. This study provides evidence that NSCs can be promoted to produce mature neurons by activating EphB2 to enhance specific brain functions.

For an organism to develop and maintain homeostasis, cell types with distinct functions must often be separated by physical boundaries. The formation and maintenance of such boundaries are commonly attributed to mechanisms restricted to the cells lining the boundary. Here we show that, besides these local subcellular mechanisms, the formation and maintenance of tissue boundaries involves long-lived, long-ranged mechanical events. Following contact between two epithelial monolayers expressing, respectively, EphB2 and its ligand ephrinB1, both monolayers exhibit oscillatory patterns of traction forces and intercellular stresses that tend to pull cell–matrix adhesions away from the boundary. With time, monolayers jam, accompanied by the emergence of deformation waves that propagate away from the boundary. This phenomenon is not specific to EphB2/ephrinB1 repulsion but is also present during the formation of boundaries with an inert interface and during fusion of homotypic epithelial layers. Our findings thus unveil a global physical mechanism that sustains tissue separation independently of the biochemical and mechanical features of the local tissue boundary. At tissue boundaries, cellular repulsive events are manifested as deformation waves that result from an oscillatory pattern of traction forces and intracellular stress that pull cellular adhesions away from the boundary.

Protein dimerization and oligomerization are essential to most cellular functions, yet measurement of the size of these oligomers in live cells, especially when their size changes over time and space, remains a challenge. A commonly used approach for studying protein aggregates in cells is number and brightness (N&B), a fluorescence microscopy method that is capable of measuring the apparent average number of molecules and their oligomerization (brightness) in each pixel from a series of fluorescence microscopy images. We have recently expanded this approach in order to allow resampling of the raw data to resolve the statistical weighting of coexisting species within each pixel. This feature makes enhanced N&B (eN&B) optimal for capturing the temporal aspects of protein oligomerization when a distribution of oligomers shifts toward a larger central size over time. In this protocol, we demonstrate the application of eN&B by quantifying receptor clustering dynamics using electron-multiplying charge-coupled device (EMCCD)-based total internal reflection microscopy (TIRF) imaging. TIRF provides a superior signal-to-noise ratio, but we also provide guidelines for implementing eN&B in confocal microscopes. For each time point, eN&B requires the acquisition of 200 frames, and it takes a few seconds up to 2 min to complete a single time point. We provide an eN&B (and standard N&B) MATLAB software package amenable to any standard confocal or TIRF microscope. The software requires a high-RAM computer (64 Gb) to run and includes a photobleaching detrending algorithm, which allows extension of the live imaging for more than an hour.This protocol describes enhanced number and brightness (eN&B), an approach that uses fluorescence fluctuation spectroscopy data to directly measure the oligomerization state and dynamics of fluorescently tagged proteins in living cells.

Invasive fungal infections (IFIs) have emerged as a significant health threat and cause approximately 3.75 million deaths per year globally. Understanding the detailed mechanism of the immune response to eliminate invasive fungal pathogens may help to provide new insights for the development of antifungal methods and drugs. Previously, we reported that the tyrosine kinase receptor EPH receptor B2 (EPHB2) is a coreceptor of β-glucan and phosphorylates Syk to activate the antifungal downstream signaling pathway. However, how EPHB2 is activated after fungal infection is still unknown. In this study, we show that EPHA5 plays a critical role in antifungal immunity by phosphorylating EPHB2 and Dectin-1 after fungal infection, which facilitates the recruitment and activation of Syk and subsequent activation of downstream antifungal signaling pathways. Additionally, we showed that EphA5 -deficient mice exhibited increased susceptibility to Candida albicans infection, with increased fungal burdens and impaired immune cell recruitment. This study provides not only a mechanistic explanation for EPHB2 and Dectin-1 activation after fungal infection but also new insights into potential therapeutic strategies for treating IFIs.