SASH1: A Novel Eph Receptor Partner and Insights into SAM-SAM Interactions.

The Eph (erythropoietin-producing human hepatocellular) receptor family, the largest subclass of receptor tyrosine kinases (RTKs), plays essential roles in embryonic development and neurogenesis. The intracellular Sterile Alpha Motif (SAM) domain presents a critical structural feature that distinguishes Eph receptors from other RTKs and participates in recruiting and binding downstream molecules. This study identified SASH1 (SAM and SH3 domain containing 1) as a novel Eph receptor-binding partner through SAM-SAM domain interactions. Our comprehensive biochemical analyses revealed that SASH1 selectively interacts with Eph receptors via its SAM1 domain, displaying the highest affinity for EphA8. The high-resolution crystal structure of the EphA8-SASH1 complex provided insights into the specific intermolecular interactions between these proteins. Cellular assays confirmed that EphA8 and SASH1 co-localize and co-precipitate in mammalian cells, with cancer mutations (EphA8 R942H or G978D) impairing this interaction. We demonstrated that SAM-SAM interaction is critical for SASH1-mediated regulation of EphA8 kinase activity, shedding new light on the Eph signaling pathway and expanding our understanding of the molecular basis of the tumor suppressor gene SASH1.

Integration of cancer-related genetic landscape of Eph receptors and ephrins with proteomics identifies a crosstalk between EPHB6 and EGFR.

Eph receptors and their ephrin ligands are viewed as promising targets for cancer treatment; however, targeting them is hindered by their context-dependent functionalities. To circumvent this, we explore molecular landscapes underlying their pro- and anti-malignant activities. Using unbiased bioinformatics approaches, we construct a cancer-related network of genetic interactions (GIs) of all Ephs and ephrins to assist in their therapeutic manipulation. We also apply genetic screening and BioID proteomics and integrate them with machine learning approaches to select the most relevant GIs of one Eph receptor, EPHB6. This identifies a crosstalk between EPHB6 and EGFR, and further experiments confirm the ability of EPHB6 to modulate EGFR signaling, enhancing the proliferation of cancer cells and tumor development. Taken together, our observations show EPHB6 involvement in EGFR action, suggesting its targeting might be beneficial in EGFR-dependent tumors, and confirm that the Eph family genetic interactome presented here can be effectively exploited in developing cancer treatment approaches.

The Functions of EphA1 Receptor Tyrosine Kinase in Several Tumors.

BACKGROUND: Eph receptors tyrosine kinase (RTK) were identified in 1987 from hepatocellular carcinoma cell lines and were the largest known subfamily of RTK. Eph receptors can be divided into two categories, EphA and EphB, based on their structure and receptor-ligand specificity. EphA can be divided into 10 species (EphA 1-10) and EphB into 6 species (EphB1-6). Similarly, the ligands of Eph receptors are Ephrins. Ephrins also can be divided into Ephrin A and Ephrin B, of which there are five species(Ephrin-A1-5) and three species(Ephrin-B1-3). Among the Eph receptors, EphA1 has been the least studied so far. As far as we know, Eph receptors are involved in multiple pathologies, including cancer progression, tumor angiogenesis, intestinal environmental stability, the lymph node system, neurological disease, and inhibition of nerve regeneration after injury. There is a link between EphA1, integrin and ECM- related signal pathways. Ephrin-A1 is a ligand of the EphA1 receptor. EphA1 and ephrin-A1 functions are related to tumor angiogenesis. EphA1 and ephrin-A1 also play roles in gynecological diseases. Ephrin-A1 and EphA1 receptors regulate the follicular formation, ovulation, embryo transport, implantation and placental formation, which are of great significance for the occurrence of gynecological tumor diseases. EphA1 has been identified as an oncoprotein in various tumors and has been associated with the prognosis of various tumors in recent years. EphA1 is considered a driver gene in tumor genomics. There are significant differences in EphA1 expression levels in different types of normal tissues and tumors and even in different stages of tumor development, suggesting its functional diversity. Changes at the gene level in cell biology are often used as biological indicators of cancer, known as biomarkers, which can be used to provide diagnostic or prognostic information and are valuable for improving the detection, monitoring and treatment of tumors. However, few prognostic markers can selectively predict clinically significant tumors with poor prognosis. These malignancies are more likely to progress and lead to death, requiring more aggressive treatment. Currently available treatments for advanced cancer are often ineffective, and treatment options are mainly palliative. Therefore, early identification and treatment of those at risk of developing malignant tumors are crucial. Although pieces of evidence have shown the role of EphA1 in tumorigenesis and development, its specific mechanism is still unknown to a great extent. OBJECTIVE: This review reveals the changes and roles of EphA1 in many tumors and cancers. The change of EphA1 expression can be used as a biological marker of cancer, which is valuable for improving tumor detection, monitoring and treatment and can be applied to imaging. Studies have shown that structural modification of EphA1 could make it an effective new drug. EphA1 is unique in that it can be considered a prognostic marker in many tumors and is of important meaning for clinical diagnosis and operative treatment. At the same time, the study of the specific mechanism of EphA1 in tumors can provide a new way for targeted therapy. METHODS: Relevant studies were retrieved and collected through the PubMed system. After determining EphA1 as the research object, by analyzing research articles on EphA1 in the PubMed system in recent 10 years, we found that EphA1 was closely connected with the occurrence and development of tumors and further determined the references according to the influencing factors for review and analysis. RESULTS: EphA1 has been identified as a cancer protein in various tumors, such as hepatocellular carcinoma, nasopharyngeal carcinoma, ovarian cancer, gastric cancer, colorectal cancer, clear cell renal cell carcinoma, esophageal squamous cell carcinoma, breast cancer, prostate cancer and uveal melanoma. EphA1 is abnormally expressed in these tumor cells, which mainly plays a role in cancer progression, tumor angiogenesis, intestinal environmental stability, the lymph node system, nervous system diseases and gynecological diseases. In a narrow sense, EphA1 is especially effective in breast cancer in terms of gynecological diseases. However, the specific mechanism of EphA1 leading to the change of cancer cells in some tumors is not clear, which needs further research and exploration. CONCLUSION: RTK EphA1 can be used as a biomarker for tumor diagnosis (especially a prognostic marker), an indispensable therapeutic target for new anti-tumor therapies, and a novel anti-tumor drug.

A non-coding variant in 5' untranslated region drove up-regulation of pseudo-kinase EPHA10 and caused non-syndromic hearing loss in humans.

Hereditary hearing loss has a genetic and phenotypic heterogeneity. However, it is still difficult to explain this heterogeneity perfectly with known deafness genes. Here, we report a novel causative gene EPHA10 as well as its non-coding variant in 5' untranslated region identified in a family with post-lingual autosomal dominant non-syndromic hearing loss from southern China. One affected member of this family had an ideal hearing restoration after cochlear implantation. We speculated that there were probable deafness-causing abnormalities in the cochlea according to clinical imaging and auditory evaluations. A heterozygous variant c.-81_-73delinsAGC was found co-segregating with hearing loss. Epha10 was expressed in mouse cochlea at both transcription and translation levels. The variant caused upregulation of EPHA10 which may result from promoter activity enhancement after sequence change. Overexpression of Eph (the homolog of human EPHA10) exerted effects on the structure and function of chordotonal organ in fly model. In summary, our study linked pseudo-kinase EPHA10 to hearing loss in humans for the first time.

Mapping the Universe of Eph Receptor and Ephrin Ligand Transcripts in Epithelial and Fiber Cells of the Eye Lens.

The eye lens is a transparent, ellipsoid organ in the anterior chamber of the eye that is required for fine focusing of light onto the retina to transmit a clear image. Cataracts, defined as any opacity in the lens, remains the leading cause of blindness in the world. Recent studies in humans and mice indicate that Eph-ephrin bidirectional signaling is important for maintaining lens transparency. Specifically, mutations and polymorphisms in the EphA2 receptor and the ephrin-A5 ligand have been linked to congenital and age-related cataracts. It is unclear what other variants of Ephs and ephrins are expressed in the lens or whether there is preferential expression in epithelial vs. fiber cells. We performed a detailed analysis of Eph receptor and ephrin ligand mRNA transcripts in whole mouse lenses, epithelial cell fractions, and fiber cell fractions using a new RNA isolation method. We compared control samples with EphA2 knockout (KO) and ephrin-A5 KO samples. Our results revealed the presence of transcripts for 12 out of 14 Eph receptors and 8 out of 8 ephrin ligands in various fractions of lens cells. Using specific primer sets, RT-PCR, and sequencing, we verified the variant of each gene that is expressed, and we found two epithelial-cell-specific genes. Surprisingly, we also identified one Eph receptor variant that is expressed in KO lens fibers but is absent from control lens fibers. We also identified one low expression ephrin variant that is only expressed in ephrin-A5 control samples. These results indicate that the lens expresses almost all Ephs and ephrins, and there may be many receptor-ligand pairs that play a role in lens homeostasis.

Eph and Ephrin Variants in Malaysian Neural Tube Defect Families.

Neural tube defects (NTDs) are common birth defects with a complex genetic etiology. Mouse genetic models have indicated a number of candidate genes, of which functional mutations in some have been found in human NTDs, usually in a heterozygous state. This study focuses on Ephs-ephrins as candidate genes of interest owing to growing evidence of the role of this gene family during neural tube closure in mouse models. Eph-ephrin genes were analyzed in 31 Malaysian individuals comprising seven individuals with sporadic spina bifida, 13 parents, one twin-sibling and 10 unrelated controls. Whole exome sequencing analysis and bioinformatic analysis were performed to identify variants in 22 known Eph-ephrin genes. We reported that three out of seven spina bifida probands and three out of thirteen family members carried a variant in either EPHA2 (rs147977279), EPHB6 (rs780569137) or EFNB1 (rs772228172). Analysis of public databases shows that these variants are rare. In exome datasets of the probands and parents of the probands with Eph-ephrin variants, the genotypes of spina bifida-related genes were compared to investigate the probability of the gene-gene interaction in relation to environmental risk factors. We report the presence of Eph-ephrin gene variants that are prevalent in a small cohort of spina bifida patients in Malaysian families.

Effects of Eph/ephrin signalling and human Alzheimer's disease-associated EphA1 on Drosophila behaviour and neurophysiology.

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease placing a great burden on people living with it, carers and society. Yet, the underlying patho-mechanisms remain unknown and treatments limited. To better understand the molecular changes associated with AD, genome-wide association studies (GWAS) have identified hundreds of candidate genes linked to the disease, like the receptor tyrosine kinase EphA1. However, demonstration of whether and how these genes cause pathology is largely lacking. Here, utilising fly genetics, we generated the first Drosophila model of human wild-type and P460L mutant EphA1 and tested the effects of Eph/ephrin signalling on AD-relevant behaviour and neurophysiology. We show that EphA1 mis-expression did not cause neurodegeneration, shorten lifespan or affect memory but flies mis-expressing the wild-type or mutant receptor were hyper-aroused, had reduced sleep, a stronger circadian rhythm and increased clock neuron activity and excitability. Over-expression of endogenous fly Eph and RNAi-mediated knock-down of Eph and its ligand ephrin affected sleep architecture and neurophysiology. Eph over-expression led to stronger circadian morning anticipation while ephrin knock-down impaired memory. A dominant negative form of the GTPase Rho1, a potential intracellular effector of Eph, led to hyper-aroused flies, memory impairment, less anticipatory behaviour and neurophysiological changes. Our results demonstrate a role of Eph/ephrin signalling in a range of behaviours affected in AD. This presents a starting point for studies into the underlying mechanisms of AD including interactions with other AD-associated genes, like Rho1, Ankyrin, Tau and APP with the potential to identify new targets for treatment.

Eph signaling is regulated by miRNA-210: Implications for corneal epithelial repair.

A distinct boundary exists between the progenitor cells in the basal limbal epithelium and the more differentiated corneal epithelial basal cells. We have shown that reciprocal expression patterns of EphA2 and Ephrin-A1 are likely to contribute to normal limbal-corneal epithelial compartmentalization as well as play a role in response to injury. How this signaling axis is regulated remains unclear. We have demonstrated that microRNAs (miRNAs) play critical roles in corneal epithelial wound healing and several miRNAs (e.g. miR-210) have been predicted to target ephrins. Previous expression profiling experiments demonstrated that miR-210 is prominently expressed in corneal epithelial cells. RNA-seq data acquired from miR-210-depleted HCECs showed up-regulation of genes involved in cellular migration. In addition, miR-210 is decreased after corneal injury while EphA2 is increased. Moreover, antago-210-treated HCECs markedly enhanced wound closure in a scratch wound assay. Antago-210 treatment resulted in increased EphA2 protein levels as well as pS897-EphA2, the pro-migratory form of EphA2. As expected, Ephrin-A1 levels were reduced, while levels of a well-known target of miR-210, Ephrin-A3, were increased by antago-210 treatment. The increase in migration with antago-210 could be inhibited by Ephrin-A1 overexpression, Ephrin-A1-Fc treatment or siRNA depletion of EphA2. However, depletion of Ephrin-A3 did not have effects on the antago-210-induced increase in migration. In addition, Ephrin-A1 overexpression and siEphA2 dampened EGFR signaling, which is increased by antago-210. Our data clearly demonstrate a link between miR-210 and EphA2/Ephrin-A1 signaling that regulates, in part, corneal epithelial migration. This interaction might potentially control the limbal-corneal epithelial boundary.

Molecular insight into the affinity, specificity and cross-reactivity of systematic hepatocellular carcinoma RALT interaction profile with human receptor tyrosine kinases.

The ErbB family of receptor tyrosine kinases (RTKs) contains four members: EGFR, ErbB2, ErbB3 and ErbB4; they are involved in the tumorigenesis of diverse cancers and can be inhibited natively by receptor-associated late transducer (RALT), a negative feedback regulator of ErbB signaling in human hepatocytes and hepatocellular carcinoma. Although the biological effects of RALT on EGFR kinase have been widely documented previously, the binding behavior of RALT to other ErbB/RTK kinases still remains largely unexplored. Here, the intermolecular interactions of RALT ErbB-binding region (EBR) as well as its functional sections and peptide segments with ErbBs and other human RTKs were systematically investigated at molecular and structural levels, from which we were able to identify those potential kinase targets of RALT protein, and to profile the affinity, specificity and cross-reactivity of RALT EBR domain and its sub-regions against various RTKs. It is revealed that RALT can target all the four ErbB kinases with high affinity for EGFR/ErbB2/ErbB4 and moderate affinity for ErbB3, but generally exhibits modest affinity to other RTKs, albeit few kinases such as LTK, EPHB6, MET and MUSK were also top-ranked as the unexpected targets of RALT. Peptide segments covering the key binding regions of RALT EBR domain were identified with computational alanine scanning, which were then optimized to obtain a number of designed peptide mutants with improved selectivity between different top-ranked RTKs.

The intracellular domains of the EphB6 and EphA10 receptor tyrosine pseudokinases function as dynamic signalling hubs.

EphB6 and EphA10 are two poorly characterised pseudokinase members of the Eph receptor family, which collectively serves as mediators of contact-dependent cell-cell communication to transmit extracellular cues into intracellular signals. As per their active counterparts, EphB6 and EphA10 deregulation is strongly linked to proliferative diseases. However, unlike active Eph receptors, whose catalytic activities are thought to initiate an intracellular signalling cascade, EphB6 and EphA10 are classified as catalytically dead, raising the question of how non-catalytic functions contribute to Eph receptor signalling homeostasis. In this study, we have characterised the biochemical properties and topology of the EphB6 and EphA10 intracellular regions comprising the juxtamembrane (JM) region, pseudokinase and SAM domains. Using small-angle X-ray scattering and cross-linking-mass spectrometry, we observed high flexibility within their intracellular regions in solution and a propensity for interaction between the component domains. We identified tyrosine residues in the JM region of EphB6 as EphB4 substrates, which can bind the SH2 domains of signalling effectors, including Abl, Src and Vav3, consistent with cellular roles in recruiting these proteins for downstream signalling. Furthermore, our finding that EphB6 and EphA10 can bind ATP and ATP-competitive small molecules raises the prospect that these pseudokinase domains could be pharmacologically targeted to counter oncogenic signalling.

Determining the effects of Ephrin Type B Receptor 6 and Type A Receptor 3 on facilitating colorectal epithelial cell malignant transformation.

Ephrin Type-A Receptor 3 (EphA3) and Ephrin Type-B Receptor 6 (EphB6) belong to the ephrin receptor group consisting of the largest subset of receptor tyrosine kinases (RTKs) and are essential for neurogenesis and embryogenesis. The current study aimed to evaluate their functional roles in transforming colorectal epithelial cells and dissect the underlying molecular mechanisms. We observed altered EphA3 and EphB6 expression in tumor tissues as compared to normal tissues in a tissue microarray study. Enforced EphB6 expression promoted IMCE cell proliferation, migration, and invasion in vitro and tumor formation in nude mice, with a stronger oncogenic activity than EphA3. Pathway analysis of differentially expressed genes from a gene microarray study provided important insight into potential mechanisms through which EphB6 may regulate the malignant transformation of colorectal epithelial cells. This study represents the first demonstration of EphB6 in enhancing colorectal epithelial cell transformation, suggesting its stipulative role in the early stage of colorectal tumorigenesis. Our findings primarily uncover novel biomarkers and therapeutic targets of colorectal cancer.

Expression Pattern and Prognostic Value of EPHA/EFNA in Breast Cancer by Bioinformatics Analysis: Revealing Its Importance in Chemotherapy.

The activities of the ephrin family in breast cancer (BrCa) are complex. Family A receptors (EPHA) and ligands (EFNA) can act as oncogenes or tumor suppressors and are implicated in chemoresistance. Here, we examined the expression pattern and prognostic value of the EPHA/EFNA family in patients with breast cancer, including patients with different subtypes or different chemotherapy cohorts. In the UALCAN database, the mRNA expression of EPHA1, EPHA10, EFNA1, EFNA3, and EFNA4 was significantly higher, whereas that of EPHA2, EPHA4, EPHA5, and EFNA5 was significantly lower in breast cancer tissues than in paracancerous tissues. The transcriptional levels of EPHA/EFNA family members were correlated with intrinsic subclasses of breast cancer. The relationship between EPHA/EFNA and the clinicopathological parameters of BrCa was analyzed using bc-GenExMiner V4.5. EPHA1, EPHA2, EPHA4, EPHA7, EFNA3, EFNA4, and EFNA5 were upregulated in estrogen receptor- (ER-) and progesterone receptor- (PR-) negative tumors, whereas EPHA3, EPHA6, and EFNA1 were upregulated in ER- and PR-positive tumors. EPHA1, EPHA2, EFNA3, and EFNA4 mRNA expression was significantly higher in human epidermal growth factor receptor 2- (HER2-) positive tumors than in HER2-negative tumors. Triple-negative status was positively correlated with EPHA1, EPHA2, EPHA4, EPHA7, EFNA3, EFNA4, and EFNA5 and negatively correlated with EPHA3 and EPHA10 mRNA expression. Genetic alterations of EPHA/EFNA in breast cancer varied from 1.1% to 10% for individual genes, as determined by the cBioPortal database. The Kaplan-Meier plotter indicated that high EphA7 mRNA expression was associated with poor overall survival (OS) and recurrence-free survival (RFS), especially in the HER2 and luminal A subtypes. EFNA4 was predicted to have poor OS and RFS in breast cancers, especially in luminal B, basal-like subtype, and patients treated with adjuvant chemotherapy. High EPHA3 expression was significantly associated with better OS and RFS, especially in the luminal A subtype, but with poor RFS in BrCa patients receiving chemotherapy. Our findings systematically elucidate the expression pattern and prognostic value of the EPHA/EFNA family in BrCa, which might provide potential prognostic factors and novel targets in BrCa patients, including those with different subtypes or treated with chemotherapy.

Coexpression of EphA10 and Gli3 promotes breast cancer cell proliferation, invasion and migration.

This study investigated the influences of EphA10 and Gli3 on breast cancer (BC) cell proliferation, invasion and migration. Immunohistochemistry was used to reveal the expressions of EphA10 and Gli3 in 18 intraductal carcinomas, 124 invasive carcinomas, 50 paracancerous tissues (2 cm away from the tumor, when possible or available), 50 lobular hyperplastic tissues and 30 normal breast tissues. qRT-PCR and Western blotting were applied to detect the expressions of EphA10 and Gli3 in invasive BC cells (MDA-MB-231, BT20 and Hs578T) and normal human mammary epithelial cells (MCF10A). MDA-MB-231 and BT20 cells were transfected with sh-EphA10, sh-Gli3 or sh-EphA10+sh-Gli3. CCK-8 was used to test the proliferation of transfected MDA-MB-231 and BT20 cells. Transwell and scratch assays were used for evaluation of invasion and migration of the transfected cells. EphA10 and Gli3 were highly expressed in invasive carcinomas and invasive BC cells. The expressions of EphA10 and Gli3 were associated with the clinicopathological characteristics and poor prognosis of patients with invasive BC. Knockdown of EphA10 or Gli3 suppressed activities of BC cells. Knockdown of both EphA10 and Gli3 was more effective than knockdown of Gli3 alone. Taken together, coexpression of EphA10 and Gli3 promotes BC cell proliferation, invasion and migration.

EPH/EPHRIN regulates cellular organization by actomyosin contractility effects on cell contacts.

EPH/EPHRIN signaling is essential to many aspects of tissue self-organization and morphogenesis, but little is known about how EPH/EPHRIN signaling regulates cell mechanics during these processes. Here, we use a series of approaches to examine how EPH/EPHRIN signaling drives cellular self-organization. Contact angle measurements reveal that EPH/EPHRIN signaling decreases the stability of heterotypic cell:cell contacts through increased cortical actomyosin contractility. We find that EPH/EPHRIN-driven cell segregation depends on actomyosin contractility but occurs independently of directed cell migration and without changes in cell adhesion. Atomic force microscopy and live cell imaging of myosin localization support that EPH/EPHRIN signaling results in increased cortical tension. Interestingly, actomyosin contractility also nonautonomously drives increased EPHB2:EPHB2 homotypic contacts. Finally, we demonstrate that changes in tissue organization are driven by minimization of heterotypic contacts through actomyosin contractility in cell aggregates and by mouse genetics experiments. These data elucidate the biomechanical mechanisms driving EPH/EPHRIN-based cell segregation wherein differences in interfacial tension, regulated by actomyosin contractility, govern cellular self-organization.

Bacterial Growth Inhibition Screen (BGIS): harnessing recombinant protein toxicity for rapid and unbiased interrogation of protein function.

In two proof-of-concept studies, we established and validated the Bacterial Growth Inhibition Screen (BGIS), which explores recombinant protein toxicity in Escherichia coli as a largely overlooked and alternative means for basic characterization of functional eukaryotic protein domains. By applying BGIS, we identified an unrecognized RNA-interacting domain in the DEK oncoprotein (this study) and successfully combined BGIS with random mutagenesis as a screening tool for loss-of-function mutants of the DNA modulating domain of DEK [1]. Collectively, our findings shed new light on the phenomenon of recombinant protein toxicity in E. coli. Given the easy and rapid implementation and wide applicability, BGIS will extend the repertoire of basic methods for the identification, analysis and unbiased manipulation of proteins.

Ephrin A4-ephrin receptor A10 signaling promotes cell migration and spheroid formation by upregulating NANOG expression in oral squamous cell carcinoma cells.

Ephrin type-A receptor 10 (EPHA10) has been implicated as a potential target for breast and prostate cancer therapy. However, its involvement in oral squamous cell carcinoma (OSCC) remains unclear. We demonstrated that EPHA10 supports in vivo tumor growth and lymphatic metastasis of OSCC cells. OSCC cell migration, epithelial mesenchymal transition (EMT), and sphere formation were found to be regulated by EPHA10, and EPHA10 was found to drive expression of some EMT- and stemness-associated transcription factors. Among EPHA10 ligands, exogenous ephrin A4 (EFNA4) induced the most OSCC cell migration and sphere formation, as well as up-regulation of SNAIL, NANOG, and OCT4. These effects were abolished by extracellular signal-regulated kinase (ERK) inhibition and NANOG knockdown. Also, EPHA10 was required for EFNA4-induced cell migration, sphere formation, and expression of NANOG and OCT4 mRNA. Our microarray dataset revealed that EFNA4 mRNA expression was associated with expression of NANOG and OCT4 mRNA, and OSCC patients showing high co-expression of EFNA4 with NANOG or OCT4 mRNA demonstrated poor recurrence-free survival rates. Targeting forward signaling of the EFNA4-EPHA10 axis may be a promising therapeutic approach for oral malignancies, and the combination of EFNA4 mRNA and downstream gene expression may be a useful prognostic biomarker for OSCC.

Single-cell transcriptomic analysis reveals key immune cell phenotypes in the lungs of patients with asthma exacerbation.

BACKGROUND: Asthma exacerbations are associated with heightened asthma symptoms, which can result in hospitalization in severe cases. However, the molecular immunologic processes that determine the course of an exacerbation remain poorly understood, impeding the progression of development of effective therapies. OBJECTIVE: Our aim was to identify candidate genes that are strongly associated with asthma exacerbation at a cellular level. METHODS: Subjects with asthma exacerbation and healthy control subjects were recruited, and bronchoalveolar lavage fluid was isolated from these subjects via bronchoscopy. Cells were isolated through fluorescence-activated cell sorting, and single-cell RNA sequencing was performed on enriched cell populations. RESULTS: We showed that the levels of monocytes, CD8+ T cells, and macrophages are significantly elevated in the bronchoalveolar lavage fluid of patients. A set of cytokines and intracellular transduction regulators are associated with asthma exacerbations and are shared across multiple cell clusters, forming a complicated molecular framework. An additional group of core exacerbation-associated modules is activated, including eukaryotic initiation factor 2 signaling, ephrin receptor signaling, and C-X-C chemokine receptor type 4 signaling in the subpopulations of CD8+ T cells (C1-a) and monocyte clusters (C7 clusters), which are associated with infection. CONCLUSION: Our study identified a significant number of severe asthma-associated genes that are differentially expressed by multiple cell clusters.

Stem-like Cells from Invasive Breast Carcinoma Cell Line MDA-MB-231 Express a Distinct Set of Eph Receptors and Ephrin Ligands.

BACKGROUND/AIM: Breast cancer cell lines consist of bulk tumor cells and a small proportion of stem-like cells. While the bulk cells are known to express a distinct combination of Eph receptors and ephrin ligands, the transcript profiles of stem-like cells in these cell lines have not been adequately characterized. The aim of this study was to determine Eph receptor/ephrin ligand profiles of cancer stem cells specific to a triple negative breast carcinoma cell line. MATERIALS AND METHODS: The normal breast cell line MCF10A and the invasive breast carcinoma cell line MDA-MB-231 were used to isolate CD24+/CD24- cell populations. The profiles of Eph receptors and ephrin ligands were determined by real-time PCR and the relative abundance in bulk and stem cells were compared. RESULTS: Based on the mean ΔCT values, the descending order of abundance was as follows. Ephrin-A5 > EPHA2 > (EPHA8, EPHB2) > ephrin-B2 > (EPHA7, EPHB4, ephrin-A4) > ephrin-A3 > ephrin-A1 > (EPHB3, ephrin-B1) > EPHA4 > EPHA1 > EPHA10. EPHA6 and ephrin-A2 transcripts were not detectable in stem cells from either cell line. The expression of EPHA4, EPHA7, EPHA8, and ephrin-A5 in MDA-MB-231 stem cells was up-regulated by 12, 20, ~500, and 6.5-fold respectively. CONCLUSION: The up-regulation of transcripts for EPHA8 and its cognate ligand, ephrin-A5, in the stem cells isolated from MDA-MB-231, suggest their involvement in the invasiveness of this cell line. Based on literature reports, we propose the role of EPHA8 and ephrin-A5 in MDA-MB-231 stem cells via the PI3K-AKT-mTOR pathway.

New insights on the modeling of the molecular mechanisms underlying neural maps alignment in the midbrain.

We previously identified and modeled a principle of visual map alignment in the midbrain involving the mapping of the retinal projections and concurrent transposition of retinal guidance cues into the superior colliculus providing positional information for the organization of cortical V1 projections onto the retinal map (Savier et al., 2017). This principle relies on mechanisms involving Epha/Efna signaling, correlated neuronal activity and axon competition. Here, using the 3-step map alignment computational model, we predict and validate in vivo the visual mapping defects in a well-characterized mouse model. Our results challenge previous hypotheses and provide an alternative, although complementary, explanation for the phenotype observed. In addition, we propose a new quantification method to assess the degree of alignment and organization between maps, allowing inter-model comparisons. This work generalizes the validity and robustness of the 3-step map alignment algorithm as a predictive tool and confirms the basic mechanisms of visual map organization.