Ephrin-A5 induces rounding, blebbing and de-adhesion of EphA3-expressing 293T and melanoma cells by CrkII and Rho-mediated signalling

Single-cell analysis of the cellular landscape of vulvar melanoma provides new insight for immunotherapy administration

BACKGROUND

Vulvar and vaginal melanoma (VuM & VaM) is a rare gynecologic malignancy with high mortality but low effectiveness to checkpoint immunotherapy compared to cutaneous melanoma. This article aims to elucidate the role of the disordered immune microenvironment in cancer progression in VuM.

METHODS

At first, this article applied single-cell RNA sequencing (scRNA-seq) to the VuM obtained from a 68-year-old female patient, and constructed a single-cell atlas of VuM consist of 12,243 single cells. Then this article explores the genomic complexity and core signal channel in VuM microenvironment.

RESULTS

This article provides new insights about the pathogenesis of VuM based on single-cell resolution data. It was found that the activation of CD8+ T cell contributed to induce tumor angiogenesis and immune escape, and the activation of the antigen-presenting molecular function participated in melanoma metastasis.

CONCLUSION

This article provided new insights into underlining VuM molecular regulation and potential signaling involved in immunotherapy, which would benefit the clinical practice and administration.

Lhx3/4 initiates a cardiopharyngeal-specific transcriptional program in response to widespread FGF signaling

Individual signaling pathways, such as fibroblast growth factors (FGFs), can regulate a plethora of inductive events. According to current paradigms, signal-dependent transcription factors (TFs), such as FGF/MapK-activated Ets family factors, partner with lineage-determining factors to achieve regulatory specificity. However, many aspects of this model have not been rigorously investigated. One key question relates to whether lineage-determining factors dictate lineage-specific responses to inductive signals or facilitate these responses in collaboration with other inputs. We utilize the chordate model Ciona robusta to investigate mechanisms generating lineage-specific induction. Previous studies in C. robusta have shown that cardiopharyngeal progenitor cells are specified through the combined activity of FGF-activated Ets1/2.b and an inferred ATTA-binding transcriptional cofactor. Here, we show that the homeobox TF Lhx3/4 serves as the lineage-determining TF that dictates cardiopharyngeal-specific transcription in response to pleiotropic FGF signaling. Targeted knockdown of Lhx3/4 leads to loss of cardiopharyngeal gene expression. Strikingly, ectopic expression of Lhx3/4 in a neuroectodermal lineage subject to FGF-dependent specification leads to ectopic cardiopharyngeal gene expression in this lineage. Furthermore, ectopic Lhx3/4 expression disrupts neural plate morphogenesis, generating aberrant cell behaviors associated with execution of incompatible morphogenetic programs. Based on these findings, we propose that combinatorial regulation by signal-dependent and lineage-determinant factors represents a generalizable, previously uncategorized regulatory subcircuit we term "cofactor-dependent induction." Integration of this subcircuit into theoretical models will facilitate accurate predictions regarding the impact of gene regulatory network rewiring on evolutionary diversification and disease ontogeny.

Methanol fixed feeder layers altered the pluripotency and metabolism of bovine pluripotent stem cells

The pluripotency maintenance of pluripotent stem cells (PSCs) requires the suitable microenvironment, which commonly provided by feeder layers. However, the preparation of feeder layers is time consuming and labor exhaustive, and the feeder cells treated with mitomycin C or γ-ray irradiation bring heterologous contamination. In this study, mouse embryonic fibroblasts (MEFs) were treated by methanol to generate chemical fixed feeder cells, and bovine embryonic stem cells F7 (bESC-F7) cultured on this feeder layer. Then the pluripotency and metabolism of bESC-F7 cultured on methanol-fixed MEFs (MT-MEFs) named MT-F7 was compared with mitomycin C treated MEFs (MC-MEFs). The results showed that bESC-F7 formed alkaline phosphatase positive colonies on MT-MEFs, the relative expression of pluripotent markers of these cells was different from the bESCs cultured on the MC-MEFs (MC-F7). The long-term cultured MT-F7 formed embryoid bodies, showed the ability to differentiate into three germ layers similar to MC-F7. The analyses of RNA-seq data showed that MT-MEFs lead bESCs to novel steady expression patterns of genes regulating pluripotency and metabolism. Furthermore, the bovine expanded pluripotent stem cells (bEPSCs) cultured on MT-MEFs formed classical colonies, maintained pluripotency, and elevated metabolism. In conclusion, MT-MEFs were efficient feeder layer that maintain the distinctive pluripotency and metabolism of PSCs.

The Hippo effector YAP1/TEAD1 regulates EPHA3 expression to control cell contact and motility

The EPHA3 protein tyrosine kinase, a member of the ephrin receptor family, regulates cell fate, cell motility, and cell-cell interaction. These cellular events are critical for tissue development, immunological responses, and the processes of tumorigenesis. Earlier studies revealed that signaling via the STK4-encoded MST1 serine-threonine protein kinase, a core component of the Hippo pathway, attenuated EPHA3 expression. Here, we investigated the mechanism by which MST1 regulates EPHA3. Our findings have revealed that the transcriptional regulators YAP1 and TEAD1 are crucial activators of EPHA3 transcription. Silencing YAP1 and TEAD1 suppressed the EPHA3 protein and mRNA levels. In addition, we identified putative TEAD enhancers in the distal EPHA3 promoter, where YAP1 and TEAD1 bind and promote EPHA3 expression. Furthermore, EPHA3 knockout by CRISPR/Cas9 technology reduced cell-cell interaction and cell motility. These findings demonstrate that EPHA3 is transcriptionally regulated by YAP1/TEAD1 of the Hippo pathway, suggesting that it is sensitive to cell contact-dependent interactions.

Cellular and molecular mechanisms of EPH/EPHRIN signaling in evolution and development

The EPH receptor tyrosine kinases and their signaling partners, the EPHRINS, comprise a large class of cell signaling molecules that plays diverse roles in development. As cell membrane-anchored signaling molecules, they regulate cellular organization by modulating the strength of cellular contacts, usually by impacting the actin cytoskeleton or cell adhesion programs. Through these cellular functions, EPH/EPHRIN signaling often regulates tissue shape. Indeed, recent evidence indicates that this signaling family is ancient and associated with the origin of multicellularity. Though extensively studied, our understanding of the signaling mechanisms employed by this large family of signaling proteins remains patchwork, and a truly "canonical" EPH/EPHRIN signal transduction pathway is not known and may not exist. Instead, several foundational evolutionarily conserved mechanisms are overlaid by a myriad of tissue -specific functions, though common themes emerge from these as well. Here, I review recent advances and the related contexts that have provided new understanding of the conserved and varied molecular and cellular mechanisms employed by EPH/EPHRIN signaling during development.

The genetic architecture of language functional connectivity

Language is a unique trait of the human species, of which the genetic architecture remains largely unknown. Through language disorders studies, many candidate genes were identified. However, such complex and multifactorial trait is unlikely to be driven by only few genes and case-control studies, suffering from a lack of power, struggle to uncover significant variants. In parallel, neuroimaging has significantly contributed to the understanding of structural and functional aspects of language in the human brain and the recent availability of large scale cohorts like UK Biobank have made possible to study language via image-derived endophenotypes in the general population. Because of its strong relationship with task-based fMRI (tbfMRI) activations and its easiness of acquisition, resting-state functional MRI (rsfMRI) have been more popularised, making it a good surrogate of functional neuronal processes. Taking advantage of such a synergistic system by aggregating effects across spatially distributed traits, we performed a multivariate genome-wide association study (mvGWAS) between genetic variations and resting-state functional connectivity (FC) of classical brain language areas in the inferior frontal (pars opercularis, triangularis and orbitalis), temporal and inferior parietal lobes (angular and supramarginal gyri), in 32,186 participants from UK Biobank. Twenty genomic loci were found associated with language FCs, out of which three were replicated in an independent replication sample. A locus in 3p11.1, regulating EPHA3 gene expression, is found associated with FCs of the semantic component of the language network, while a locus in 15q14, regulating THBS1 gene expression is found associated with FCs of the perceptual-motor language processing, bringing novel insights into the neurobiology of language.

The roles of Cdc42 and Rac1 in the formation of plasma membrane protrusions in cancer epithelial HeLa cells

The inducible model of clones generated from the cervical cancer epithelial HeLa cell line has shown the role of DOCK10 as a guanine-nucleotide exchange factor for Rho GTPases Cdc42 and Rac1 and as an inducer of filopodia and plasma membrane (PM) ruffles. In this model, constitutively active (CA) mutants of Cdc42 and Rac1 promote filopodia and ruffles, respectively, as in other models. DOCK9 also induces filopodia and ruffles, although ruffling activity is less prominent. By exploiting this model further, the aim of this work is to provide a more complete understanding of the role of Cdc42 and Rac1, and their interactions with DOCK10 and DOCK9, in regulation of PM protrusions. New clones have been generated from HeLa, including single clones expressing one form of wild-type (WT) or dominant negative (DN) Cdc42 or Rac1, and double clones co-expressing one of them together with either DOCK10 or DOCK9. Expression of WT- and DN-Cdc42 induced filopodia. WT-Cdc42 and, especially, DN-Cdc42 also gave rise to veil protrusions, which were neutralized by DOCK10. Moreover, DN-Cdc42 stimulated the emergence of ruffles, further increased by DOCK10, and WT-Cdc42 also augmented ruffles in presence of DOCK9 and DOCK10. WT-Rac1 greatly increased PM blebbing, as did DN-Rac1 more moderately. In both cases, blebs were enhanced by DOCK10. DN-Rac1 and CA-Rac1 moderately raised filopodia, and DOCK10 and DOCK9 had opposed effects on filopodia (up and down, respectively) in presence of WT-Rac1. As conclusions, we highlight that Cdc42 promotes filopodia regardless of its conformational state, and Rac1 induces blebs in conformations other than CA, especially WT-Rac1, in the inducible HeLa clones. The model could be useful to learn more about the mechanisms underlying PM protrusions.

Presenilin/γ-secretase-dependent EphA3 processing mediates axon elongation through non-muscle myosin IIA

EphA/ephrin signaling regulates axon growth and guidance of neurons, but whether this process occurs also independently of ephrins is unclear. We show that presenilin-1 (PS1)/γ-secretase is required for axon growth in the developing mouse brain. PS1/γ-secretase mediates axon growth by inhibiting RhoA signaling and cleaving EphA3 independently of ligand to generate an intracellular domain (ICD) fragment that reverses axon defects in PS1/γ-secretase- and EphA3-deficient hippocampal neurons. Proteomic analysis revealed that EphA3 ICD binds to non-muscle myosin IIA (NMIIA) and increases its phosphorylation (Ser1943), which promotes NMIIA filament disassembly and cytoskeleton rearrangement. PS1/γ-secretase-deficient neurons show decreased phosphorylated NMIIA and NMIIA/actin colocalization. Moreover, pharmacological NMII inhibition reverses axon retraction in PS-deficient neurons suggesting that NMIIA mediates PS/EphA3-dependent axon elongation. In conclusion, PS/γ-secretase-dependent EphA3 cleavage mediates axon growth by regulating filament assembly through RhoA signaling and NMIIA, suggesting opposite roles of EphA3 on inhibiting (ligand-dependent) and promoting (receptor processing) axon growth in developing neurons.

Eph receptor signalling: from catalytic to non-catalytic functions

Eph receptors, the largest subfamily of receptor tyrosine kinases, are linked with proliferative disease, such as cancer, as a result of their deregulated expression or mutation. Unlike other tyrosine kinases that have been clinically targeted, the development of therapeutics against Eph receptors remains at a relatively early stage. The major reason is the limited understanding on the Eph receptor regulatory mechanisms at a molecular level. The complexity in understanding Eph signalling in cells arises due to following reasons: (1) Eph receptors comprise 14 members, two of which are pseudokinases, EphA10 and EphB6, with relatively uncharacterised function; (2) activation of Eph receptors results in dimerisation, oligomerisation and formation of clustered signalling centres at the plasma membrane, which can comprise different combinations of Eph receptors, leading to diverse downstream signalling outputs; (3) the non-catalytic functions of Eph receptors have been overlooked. This review provides a structural perspective of the intricate molecular mechanisms that drive Eph receptor signalling, and investigates the contribution of intra- and inter-molecular interactions between Eph receptors intracellular domains and their major binding partners. We focus on the non-catalytic functions of Eph receptors with relevance to cancer, which are further substantiated by exploring the role of the two pseudokinase Eph receptors, EphA10 and EphB6. Throughout this review, we carefully analyse and reconcile the existing/conflicting data in the field, to allow researchers to further the current understanding of Eph receptor signalling.

Converting a weaker ATP-binding site inhibitor into a potent hetero-bivalent ligand by tethering to a unique peptide sequence derived from the same kinase

Attaching an additional binding site directed moiety or a ligand to an ATP-binding site inhibitor has been used as a strategy to increase kinase binding affinity and specificity. The moieties typically used here as the second binding partner are varied from simple organic groups to ligands such as peptides derived from substrate binding site sequences. So far these hetero-bivalent ligands were developed targeting additional binding sites closer to the ATP-binding pocket. Here we report a unique expansion of this hetero-bivalent idea by: (I) targeting a new binding site much farther away from ATP-binding site, (II) using a peptide uniquely derived from a portion of the same kinase sequence that has been reported to turn and bind to the above distance binding pocket (used as the second binding ligand), and (III) optimizing a much longer and flexible linker (to connect ATP-binding site inhibitor and above mentioned second peptide sequence) with multistep, yet complete on-bead synthesis approach. We converted a very weak EphA3-kinase ATP-binding site inhibitor-PP2 into a potent hetero-bivalent ligand by tethering to a unique 5-mer peptide sequence that derived from the linker region of EphA3 that connects kinase and sterile alpha motif (SAM) domains. Our design highlight the use of distance binding pockets to ATP-binding site as the second targeted site, while introducing the idea of extracting natural peptide sequences that already exist within the same kinase sequence, by a careful screening of available crystal structures.

Novel genetic associations with interferon in systemic lupus erythematosus identified by replication and fine-mapping of trait-stratified genome-wide screen

BACKGROUND/PURPOSE

High serum interferon alpha (IFN-α) is an important heritable phenotype in systemic lupus erythematosus (SLE) which is involved in primary disease pathogenesis. High vs. low levels of IFN-α are associated with disease severity and account for some of the biological heterogeneity between SLE patients. The aim of the study was to replicate and fine-map previously detected genetic associations with serum IFN-α in SLE.

METHODS

We previously undertook a case-case genome-wide association study of SLE patients stratified by ancestry and extremes of phenotype in serum IFN-α. Single nucleotide polymorphisms (SNPs) in seven loci identified in this screen were selected for follow up in a large independent cohort of 1370 SLE patients (703 European-ancestry, 432 African ancestry, and 235 Amerindian ancestry). Each ancestral background was analyzed separately, and ancestry-informative markers were used to control for ancestry and admixture.

RESULTS

We find a rare haplotype spanning the promoter region of EFNA5 that is strongly associated with serum IFN-α in both African-American and European-American SLE patients (OR = 3.0, p = 3.7 × 10^-6). We also find SNPs in the PPM1H, PTPRM, and NRGN regions associated with IFN-α levels in European-American, Amerindian, and African-American SLE patients respectively. Many of these associations are within regulatory regions of the gene, suggesting an impact on transcription.

CONCLUSION

This study demonstrates the power of molecular sub-phenotypes to reveal genetic factors involved in complex autoimmune disease. The distinct associations observed in different ancestral backgrounds emphasize the heterogeneity of molecular pathogenesis in SLE.

EphA3 inhibits migration and invasion of esophageal cancer cells by activating the mesenchymal‑epithelial transition process

Eph receptor tyrosine kinases are critical for cell‑cell communication during normal and oncogenic development. Eph receptor A3 (EphA3) expression is associated with tumor promotion in certain types of cancer; however, it acts as a tumor suppressor in others. The expression levels of EphA3 and its effects on tumor progression in esophageal squamous cell carcinoma (ESCC) cell lines were determined using reverse transcription‑quantitative polymerase chain reaction analysis and a Transwell invasion assay. The present study demonstrated that EphA3 expression was decreased in ESCC tissues and cell lines. Treatment with the DNA methylation inhibitor 5‑aza‑2'‑deoxycytidine increased the mRNA expression levels of EphA3 in the ESCC cell lines KYSE510 and KYSE30. In addition, overexpression of EphA3 in KYSE450 and KYSE510 cells inhibited cell migration and invasion. EphA3 overexpression also decreased RhoA GTPase. Furthermore, EphA3 overexpression induced mesenchymal‑epithelial transition, as demonstrated by epithelial‑like morphological alterations, increased expression of epithelial proteins (E‑cadherin and the tight junction protein 1 zonula occludens‑1) and decreased expression of mesenchymal proteins (Vimentin, N‑cadherin and Snail). Conversely, silencing EphA3 in KYSE410 cells triggered epithelial‑mesenchymal transition, and promoted cell migration and invasion. These results suggested that EphA3 may serve a tumor‑suppressor role in ESCC.

MiR-340 suppresses the metastasis by targeting EphA3 in cervical cancer

MicroRNAs (miRNAs) play key roles in cervical cancer metastasis progression. Accumulated evidences have revealed that miRNAs are related to the pathophysiological process. However, the role of miR-340 in cervical cancer and how it works is still not fully interpreted. Using qRT-PCR to examine the expression of miR-340 in cervical cancer tissues. Transwell migration and invasion experiments were used to detect the role of miR-340 in migration and invasion. Luciferase reporter assay, qRT-PCR, and Western blot were used to detect the relationship between miR-340 and EphA3. Using Transwell migration and invasion experiments to investigate the role of EphA3 on migration and invasion. Restoration expriments were also performed. Western blot was used to assay the influence of miR-340 and EphA3 on EMT. We found that miR-340 was downregulated in cervical cancer tissues compared with the normal tissues. Transwell migration and invasion experiments indicated that overexpression of miR-340 frequently inhibited the migration and invasion of cervical cancer cells. EphA3 is a target of miR-340, and ectopic expression of EphA3 can promote the migration and invasion of cervical cancer cells, whereas restoration of EphA3 in miR-340-overexpressing cervical cancer cells reversed the suppressive effects of miR-340. What's more, the process of migration and invasion which regulated by miR-340/EphA3 was depended on adjusting the EMT way. These findings indicate that miR-340 may act as an anti-tumor factor during the process of tumor metastasis through targeting EphA3, suggesting that miR-340 might be a potential new diagnostic and therapeutic molecule for the treatment of cervical cancer.

Association of EPHA3 Gene Polymorphisms with Nonsyndromic Cleft Lip With or Without Cleft Palate

AIMS

Nonsyndromic cleft lip with or without palate (NSCL/P) represents a complex condition caused by genetic and environmental factors. The aim of this study was to investigate the relationship between the EPHA3 polymorphisms and NSCL/P.

MATERIALS AND METHODS

To investigate the relationship between five EPHA3 single nucleotide polymorphisms (SNPs) and NSCL/P, we selected 180 affected patients and 167 normal controls from the Chinese Han Population. EPHA3 SNPs (rs7650466, rs1398197, rs17801309, rs1054750, and rs7632427) were genotyped using the SNaPshot technique; bioinformatic analyses were performed to determine if any of them were potentially functional SNPs.

RESULTS

The rs7650466 T allele was associated with the incidence of NSCL/P (OR, 0.211; 95% CI, 0.131-0.338; adjusted p = 4.881 × 10^-10) and cleft lip with or without palate (CL/P) (OR, 0.176; 95% CI, 0.104-0.297; adjusted p = 3.617 × 10^-10), as well as with protective and dominant effects in both conditions. The rs7650466 T allele could be associated with reduced risk of the malformation. In a bioinformatics analysis, we found potential matching sites (miR-1255a, miR-125a-3p, miR-143, and miR-552) for rs7650466 and preliminarily analyzed its potential function.

CONCLUSIONS

Collectively, our data suggest that the EPHA3 rs7650466 polymorphism confers genetic risk for NSCL/P in the Chinese Han Population. Furthermore, rs7650466 is associated with CL/P incidence in stratified analyses, but not with cleft palate only.

Specific Eph receptor-cytoplasmic effector signaling mediated by SAM-SAM domain interactions

The Eph receptor tyrosine kinase (RTK) family is the largest subfamily of RTKs playing critical roles in many developmental processes such as tissue patterning, neurogenesis and neuronal circuit formation, angiogenesis, etc. How the 14 Eph proteins, via their highly similar cytoplasmic domains, can transmit diverse and sometimes opposite cellular signals upon engaging ephrins is a major unresolved question. Here, we systematically investigated the bindings of each SAM domain of Eph receptors to the SAM domains from SHIP2 and Odin, and uncover a highly specific SAM-SAM interaction-mediated cytoplasmic Eph-effector binding pattern. Comparative X-ray crystallographic studies of several SAM-SAM heterodimer complexes, together with biochemical and cell biology experiments, not only revealed the exquisite specificity code governing Eph/effector interactions but also allowed us to identify SAMD5 as a new Eph binding partner. Finally, these Eph/effector SAM heterodimer structures can explain many Eph SAM mutations identified in patients suffering from cancers and other diseases.

Epha3 acts as proangiogenic factor in multiple myeloma

This study investigates the role of ephrin receptor A3 (EphA3) in the angiogenesis of Multiple Myeloma (MM) and the effects of a selective target of EphA3 by a specific monoclonal antibody on primary bone marrow endothelial cells (ECs) of MM patients.

EphA3 mRNA and protein were evaluated in ECs of MM patients (MMECs), in ECs of patients with monoclonal gammopathies of undetermined significance (MGECs) and in ECs of healthy subjects (control ECs). The effects of EphA3 targeting by mRNA silencing (siRNA) or by the anti EphA3 antibody on the angiogenesis were evaluated. We found that EphA3 is highly expressed in MMECs compared to the other EC types. Loss of function of EphA3 by siRNA significantly inhibited the ability of MMECs to adhere to fibronectin, to migrate and to form tube like structures in vitro, without affecting cell proliferation or viability. In addition, gene expression profiling showed that knockdown of EphA3 down modulated some molecules that regulate adhesion, migration and invasion processes. Interestingly, EphA3 targeting by an anti EphA3 antibody reduced all the MMEC angiogenesis-related functions in vitro. In conclusion, our findings suggest that EphA3 plays an important role in MM angiogenesis.

The EphA2 receptor is activated through induction of distinct, ligand-dependent oligomeric structures

The EphA2 receptor tyrosine kinase is capable of activating multiple diverse signaling pathways with roles in processes such as tissue homeostasis and cancer. EphA2 is known to form activated oligomers in the presence of ephrin-A ligands. Here, we characterize the lateral interactions between full-length EphA2 molecules in the plasma membrane in the presence of three types of ligands (dimeric ephrinA1-Fc, monomeric ephrinA1, and an engineered peptide ligand) as well as in the absence of ligand, using a quantitative FRET technique. The data show that EphA2 forms higher-order oligomers and two different types of dimers that all lead to increased EphA2 tyrosine phosphorylation, which is indicative of increased kinase-dependent signaling. We find that different ligands stabilize conformationally distinct oligomers that are assembled through two different interfaces. Our results suggest that these different oligomeric assemblies could have distinct signaling properties, contributing to the diverse activities of the EphA2 receptor.

Deo Singh et al. use Fully Quantified Spectral Imaging-FRET to show that the EphA2 receptor forms dimers or higher order oligomers depending on the type of ligand, and that different ligands stabilize EphA2 dimers through distinct interfaces. These findings may explain how EphA2 activates diverse signaling pathways.

Coupled regulation by the juxtamembrane and sterile α motif (SAM) linker is a hallmark of ephrin tyrosine kinase evolution

Ephrin (Eph) receptor tyrosine kinases have evolutionarily diverged from other tyrosine kinases to respond to specific activation and regulatory signals that require close coupling of kinase catalytic and regulatory functions. However, the evolutionary basis for such functional coupling is not fully understood. We employed an evolutionary systems approach involving statistical mining of large sequence and structural data sets to define the hallmarks of Eph kinase evolution and functional specialization. We found that some of the most distinguishing Eph-specific residues structurally tether the flanking juxtamembrane and sterile α motif (SAM) linker regions to the kinase domain, and substitutions of these residues in EphA3 resulted in faster kinase activation. We report for the first time that the SAM domain linker is functionally coupled to the juxtamembrane through co-conserved residues in the kinase domain and that together these residues provide a structural framework for coupling catalytic and regulatory functions. The unique organization of Eph-specific tethering networks and the identification of other Eph-specific sequence features of unknown functions provide new hypotheses for future functional studies and new clues to disease mutations altering Eph kinase-specific functions.

Roles of Eph/ephrin bidirectional signaling in central nervous system injury and recovery

Multiple cellular components are involved in the complex pathological process following central nervous system (CNS) injury, including neurons, glial cells and endothelial cells. Previous studies and neurotherapeutic clinical trials have assessed the molecular mechanisms that underlie neuronal cell death following CNS injury. However, this approach has largely failed to reduce CNS damage or improve the functional recovery of patients. Erythropoietin-producing human hepatocellular (Eph) receptors and ephrin ligands have attracted considerable attention since their discovery, due to their extensive distribution and unique bidirectional signaling between astrocytes and neurons. Previous studies have investigated the roles of Eph/ephrin bidirectional signaling in the developing central nervous system. It was determined that Eph/ephrin bidirectional signaling is expressed in various CNS regions and cell types, and that it serves diverse roles in the adult CNS. In the present review, the roles of Eph/ephrin bidirectional signaling in CNS injuries are assessed.

Roles of Eph/ephrin bidirectional signaling during injury and recovery of the central nervous system

Multiple cellular components, including neuronal, glial and endothelial cells, are involved in the sophisticated pathological processes following central nervous system injury. The pathological process cannot reduce damage or improve functional recovery by merely targeting the molecular mechanisms of neuronal cell death after central nerve system injuries. Eph receptors and ephrin ligands have drawn wide attention since the discovery of their extensive distribution and unique bidirectional signaling between astrocytes and neurons. The roles of Eph/ephrin bidirectional signaling in the developmental processes have been reported in previous research. Recent observations suggest that Eph/ephrin bidirectional signaling continues to be expressed in most regions and cell types in the adult central nervous system, playing diverse roles. The Eph/ephrin complex mediates neurogenesis and angiogenesis, promotes glial scar formation, regulates endocrine levels, inhibits myelin formation and aggravates inflammation and nerve pain caused by injury. The interaction between Eph and ephrin is also considered to be the key to angiogenesis. This review focuses on the roles of Eph/ephrin bidirectional signaling in the repair of central nervous system injuries.

Targeted therapies in hematological malignancies using therapeutic monoclonal antibodies against Eph family receptors

The use of monoclonal antibodies (mAbs) and molecules derived from them has achieved considerable attention and success in recent years, establishing this mode of therapy as an important therapeutic strategy in many cancers, in particular hematological tumors. mAbs recognize cell surface antigens expressed on target cells and mediate their function through various mechanisms such as antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, or immune system modulation. The efficacy of mAb therapy can be improved when they are conjugated to a highly potent payloads, including cytotoxic drugs and radiolabeled isotopes. The Eph family of proteins has received considerable attention in recent years as therapeutic targets for treatment of both solid and hematological cancers. High expression of Eph receptors on cancer cells compared with low expression levels in normal adult tissues makes them an attractive candidate for cancer immunotherapy. In this review, we detail the modes of action of antibody-based therapies with a focus on the Eph family of proteins as potential targets for therapy in hematological malignancies.

Investigation of the role of tyrosine kinase receptor EPHA3 in colorectal cancer

EPH signaling deregulation has been shown to be important for colorectal carcinogenesis and genome-wide sequencing efforts have identified EPHA3 as one of the most frequently mutated genes in these tumors. However, the role of EPHA3 in colorectal cancer has not been thoroughly investigated. We show here that ectopic expression of wild type EPHA3 in colon cancer cells did not affect their growth, motility/invasion or metastatic potential in vivo. Moreover, overexpression of mutant EPHA3 or deletion of the endogenous mutant EPHA3 in colon cancer cells did not affect their growth or motility. EPHA3 inactivation in mice did not initiate the tumorigenic process in their intestine, and had no effects on tumor size/multiplicity after tumor initiation either genetically or pharmacologically. In addition, immunohistochemical analysis of EPHA3 tumor levels did not reveal associations with survival or clinicopathological features of colorectal cancer patients. In conclusion, we show that EPHA3 does not play a major role in colorectal tumorigenesis. These results significantly contribute to our understanding of the role of EPH signaling during colorectal carcinogenesis, and highlighting the need for detailed functional studies to confirm the relevance of putative cancer driver genes identified in sequencing efforts of the cancer genome.

Wnt Signaling in Cell Motility and Invasion: Drawing Parallels between Development and Cancer

The importance of canonical and non-canonical Wnt signal transduction cascades in embryonic development and tissue homeostasis is well recognized. The aberrant activation of these pathways in the adult leads to abnormal cellular behaviors, and tumor progression is frequently a consequence. Here we discuss recent findings and analogies between Wnt signaling in developmental processes and tumor progression, with a particular focus on cell motility and matrix invasion and highlight the roles of the ARF (ADP-Ribosylation Factor) and Rho-family small GTP-binding proteins. Wnt-regulated signal transduction from cell surface receptors, signaling endosomes and/or extracellular vesicles has the potential to profoundly influence cell movement, matrix degradation and paracrine signaling in both development and disease.

The extracellular interactome of the human adenovirus family reveals diverse strategies for immunomodulation

Viruses encode secreted and cell-surface expressed proteins essential to modulate host immune defenses and establish productive infections. However, to date there has been no systematic study of the extracellular interactome of any human virus. Here we utilize the E3 proteins, diverse and rapidly evolving transmembrane-containing proteins encoded by human adenoviruses, as a model system to survey the extracellular immunomodulatory landscape. From a large-scale protein interaction screen against a microarray of more than 1,500 human proteins, we find and validate 51 previously unidentified virus–host interactions. Our results uncover conserved strategies as well as substantial diversity and multifunctionality in host targeting within and between viral species. Prominent modulation of the leukocyte immunoglobulin-like and signalling lymphocyte activation molecule families and a number of inhibitory receptors were identified as hubs for viral perturbation, suggesting unrecognized immunoregulatory strategies. We describe a virus–host extracellular interaction map of unprecedented scale that provides new insights into viral immunomodulation.

Viruses interact with their hosts via secreted and membrane-bound proteins to affect host immune responses and virulence. Here the authors contribute to our understanding of this relationship with an extracellular interaction map of human and adenoviral E3 immunomodulatory proteins.

EPHA3 regulates the multidrug resistance of small cell lung cancer via the PI3K/BMX/STAT3 signaling pathway

Multidrug resistance (MDR) is a major obstacle to the treatment of small cell lung cancer (SCLC). EPHA3 has been revealed to be the most frequently mutated Eph receptor gene in lung cancer with abnormal expression. Growing evidence indicates that the signaling proteins of EPHA3 downstream, including PI3K, BMX and STAT3, play crucial roles in tumorigenesis and cancer progression. To explore the possible role of EPHA3 in MDR, we assessed the influence of EPHA3 on chemoresistance, cell cycle, apoptosis, and tumor growth, as well as the relationship between EPHA3 and the expression of PI3K, BMX, and STAT3 in SCLC. We observed that overexpression of EPHA3 in SCLC cells decreased chemoresistance by increasing apoptosis and inducing G0/G1 arrest, accompanied by reduced phosphorylation of PI3K/BMX/STAT3 signaling pathway. Knockdown of EPHA3 expression generated a resistant phenotype of SCLC, as a result of decreased apoptosis and induced G2/M phase arrest. And re-expression of EPHA3 in these cells reversed the resistant phenotype. Meanwhile, increased phosphorylation of PI3K/BMX/STAT3 signaling pathway was observed in these cells with EPHA3 deficiency. Notably, both PI3K inhibitor (LY294002) and BMX inhibitor (LFM-A13) impaired the chemoresistance enhanced by EPHA3 deficiency in SCLC cell lines. Furthermore, EPHA3 inhibited growth of SCLC cells in vivo and was correlated with longer overall survival of SCLC patients. Thus, we first provide the evidences that EPHA3 is involved in regulating the MDR of SCLC via PI3K/BMX/STAT3 signaling and may be a new therapeutic target in SCLC.

PTP-PEST controls EphA3 activation and ephrin-induced cytoskeletal remodelling

Eph receptors and their corresponding membrane-bound ephrin ligands regulate cell positioning and establish tissue patterns during embryonic and oncogenic development. Emerging evidence suggests that assembly of polymeric Eph signalling clusters relies on cytoskeletal reorganisation and underlies regulation by protein tyrosine phosphatases (PTPs). PTP-PEST (also known as PTPN12) is a central regulator of actin cytoskeletal dynamics. Here, we demonstrate that an N-terminal fragment of PTP-PEST, generated through an ephrinA5-triggered and spatially confined cleavage mediated by caspase-3, attenuates EphA3 receptor activation and its internalisation. Isolation of EphA3 receptor signalling clusters within intact plasma membrane fragments obtained by detergent-free cell fractionation reveals that stimulation of cells with ephrin triggers effective recruitment of this catalytically active truncated form of PTP-PEST together with key cytoskeletal and focal adhesion proteins. Importantly, modulation of actin polymerisation using pharmacological and dominant-negative approaches affects EphA3 phosphorylation in a similar manner to overexpression of PTP-PEST. We conclude that PTP-PEST regulates EphA3 activation both by affecting cytoskeletal remodelling and through its direct action as a PTP controlling EphA3 phosphorylation, indicating its multifaceted regulation of Eph signalling.

Unliganded EphA3 dimerization promoted by the SAM domain

The erythropoietin-producing hepatocellular carcinoma A3 (EphA3) receptor tyrosine kinase (RTK) regulates morphogenesis during development and is overexpressed and mutated in a variety of cancers. EphA3 activation is believed to follow a 'seeding mechanism' model, in which ligand binding to the monomeric receptor acts as a trigger for signal-productive receptor clustering. We study EphA3 lateral interactions on the surface of live cells and we demonstrate that EphA3 forms dimers in the absence of ligand binding. We further show that these dimers are stabilized by interactions involving the EphA3 sterile α-motif (SAM) domain. The discovery of unliganded EphA3 dimers challenges the current understanding of the chain of EphA3 activation events and suggests that EphA3 may follow the 'pre-formed dimer' model of activation known to be relevant for other receptor tyrosine kinases. The present work also establishes a new role for the SAM domain in promoting Eph receptor lateral interactions and signalling on the cell surface.

Autophagy is required for stem cell mobilization by G-CSF

G-CSF activates autophagy in HSCs and neutrophils. The response and survival of HSCs mobilized by G-CSF in vivo require autophagy.

Targeting EphA3 inhibits cancer growth by disrupting the tumor stromal microenvironment

Eph receptor tyrosine kinases are critical for cell-cell communication during normal and oncogenic tissue patterning and tumor growth. Somatic mutation profiles of several cancer genomes suggest EphA3 as a tumor suppressor, but its oncogenic expression pattern and role in tumorigenesis remain largely undefined. Here, we report unexpected EphA3 overexpression within the microenvironment of a range of human cancers and mouse tumor xenografts where its activation inhibits tumor growth. EphA3 is found on mouse bone marrow-derived cells with mesenchymal and myeloid phenotypes, and activation of EphA3(+)/CD90(+)/Sca1(+) mesenchymal/stromal cells with an EphA3 agonist leads to cell contraction, cell-cell segregation, and apoptosis. Treatment of mice with an agonistic α-EphA3 antibody inhibits tumor growth by severely disrupting the integrity and function of newly formed tumor stroma and microvasculature. Our data define EphA3 as a novel target for selective ablation of the tumor microenvironment and demonstrate the potential of EphA3 agonists for anticancer therapy.

A mathematical model for eph/ephrin-directed segregation of intermingled cells

Eph receptors, the largest family of receptor tyrosine kinases, control cell-cell adhesion/de-adhesion, cell morphology and cell positioning through interaction with cell surface ephrin ligands. Bi-directional signalling from the Eph and ephrin complexes on interacting cells have a significant role in controlling normal tissue development and oncogenic tissue patterning. Eph-mediated tissue patterning is based on the fine-tuned balance of adhesion and de-adhesion reactions between distinct Eph- and ephrin-expressing cell populations, and adhesion within like populations (expressing either Eph or ephrin). Here we develop a stochastic, Lagrangian model that is based on Eph/ephrin biology: incorporating independent Brownian motion to describe cell movement and a deterministic term (the drift term) to represent repulsive and adhesive interactions between neighbouring cells. Comparison between the experimental and computer simulated Eph/ephrin cell patterning events shows that the model recapitulates the dynamics of cell-cell segregation and cell cluster formation. Moreover, by modulating the term for Eph/ephrin-mediated repulsion, the model can be tuned to match the actual behaviour of cells with different levels of Eph expression or activity. Together the results of our experiments and modelling suggest that the complexity of Eph/ephrin signalling mechanisms that control cell-cell interactions can be described well by a mathematical model with a single term balancing adhesion and de-adhesion between interacting cells. This model allows reliable prediction of Eph/ephrin-dependent control of cell patterning behaviour.

A high affinity recombinant antibody to the human EphA3 receptor with enhanced ADCC activity

EphA3 is expressed in solid tumors and leukemias and is an attractive target for the therapy. We have generated a panel of Humaneered® antibodies to the ligand-binding domain using a Fab epitope-focused library that has the same specificity as monoclonal antibody mIIIA4. A high-affinity antibody was selected that competes with the mIIIA4 antibody for binding to EphA3 and has an improved affinity of ∼1 nM. In order to generate an antibody with potent cell-killing activity the variable regions were assembled with human IgG1k constant regions and expressed in a Chinese hamster ovary (CHO) cell line deficient in fucosyl transferase. Non-fucosylated antibodies have been reported to have enhanced binding affinity for the IgG receptor CD16a (FcγRIIIa). The affinity of the antibody for recombinant CD16a was enhanced approximately 10-fold. This resulted in enhanced antibody-dependent cell-mediated cytotoxicity (ADCC) activity against EphA3-expressing leukemic cells, providing a potent antibody for the evaluation as a therapeutic agent.

EphA3 biology and cancer

Eph receptor tyrosine kinases control cell-cell interactions during normal and oncogenic development, and are implicated in a range of processes including angiogenesis, stem cell maintenance and metastasis. They are thus of great interest as targets for cancer therapy. EphA3, originally isolated from leukemic and melanoma cells, is presently one of the most promising therapeutic targets, with multiple tumor-promoting roles in a variety of cancer types. This review focuses on EphA3, its functions in controlling cellular behavior, both in normal and pathological development, and most particularly in cancer.

Hypoxia-controlled EphA3 marks a human endometrium-derived multipotent mesenchymal stromal cell that supports vascular growth

Eph and ephrin proteins are essential cell guidance cues that orchestrate cell navigation and control cell-cell interactions during developmental tissue patterning, organogenesis and vasculogenesis. They have been extensively studied in animal models of embryogenesis and adult tissue regeneration, but less is known about their expression and function during human tissue and organ regeneration. We discovered the hypoxia inducible factor (HIF)-1α-controlled expression of EphA3, an Eph family member with critical functions during human tumour progression, in the vascularised tissue of regenerating human endometrium and on isolated human endometrial multipotent mesenchymal stromal cells (eMSCs), but not in other highly vascularised human organs. EphA3 affinity-isolation from human biopsy tissue yielded multipotent CD29⁺/CD73⁺/CD90⁺/CD146⁺ eMSCs that can be clonally propagated and respond to EphA3 agonists with EphA3 phosphorylation, cell contraction, cell-cell segregation and directed cell migration. EphA3 silencing significantly inhibited the ability of transplanted eMSCs to support neovascularisation in immunocompromised mice. In accord with established roles of Eph receptors in mediating interactions between endothelial and perivascular stromal cells during mouse development, our findings suggest that HIF-1α-controlled expression of EphA3 on human MSCs functions during the hypoxia-initiated early stages of adult blood vessel formation.

Eph- and ephrin-dependent mechanisms in tumor and stem cell dynamics

The erythropoietin-producing hepatocellular (Eph) receptors comprise the largest family of receptor tyrosine kinases (RTKs). Initially regarded as axon-guidance and tissue-patterning molecules, Eph receptors have now been attributed with various functions during development, tissue homeostasis, and disease pathogenesis. Their ligands, ephrins, are synthesized as membrane-associated molecules. At least two properties make this signaling system unique: (1) the signal can be simultaneously transduced in the receptor- and the ligand-expressing cell, (2) the signaling outcome through the same molecules can be opposite depending on cellular context. Moreover, shedding of Eph and ephrin ectodomains as well as ligand-dependent and -independent receptor crosstalk with other RTKs, proteases, and adhesion molecules broadens the repertoire of Eph/ephrin functions. These integrated pathways provide plasticity to cell-microenvironment communication in varying tissue contexts. The complex molecular networks and dynamic cellular outcomes connected to the Eph/ephrin signaling in tumor-host communication and stem cell niche are the main focus of this review.

Anti-adhesive property of P-selectin glycoprotein ligand-1 (PSGL-1) due to steric hindrance effect

P-selectin glycoprotein ligand-1 (PSGL-1) is an adhesive molecule that is known to be a ligand for P-selectin. An anti-adhesive property of PSGL-1 has not been previously reported. In this study, we show that PSGL-1 expression is anti-adhesive for adherent cells and we have elucidated the underlying mechanism. Overexpression of PSGL-1 induced cell rounding and floating in HEK293T cells. Similar phenomena were demonstrated in other adherent cell lines with overexpression of PSGL-1. PSGL-1 overexpression inhibits access of antibodies to cell surface molecules such as integrins, HLA and CD25. Cells transfected with PSGL-1 deletion mutants that lack a large part of the extracellular domain and chimeric construct expressing extracellular CD86 and intracellular PSGL-1 only showed rounded morphology, but there are no floating cells. These results indicated that PSGL-1 causes steric hindrance due to the extended structure of its extracellular domain that is highly O-glycosylated, but intracellular domain also has some effect on cell rounding. This study implies that PSGL-1 has Janus-faced functions, being both adhesive and anti-adhesive.

EphA receptors regulate prostate cancer cell dissemination through Vav2-RhoA mediated cell-cell repulsion

Metastatic prostate cancer cells display EphB receptor-mediated attraction when they contact stromal fibroblasts but EphA-driven repulsion when they contact one another. The impact of these ‘social’ interactions between cells during cancer cell invasion and the signalling mechanisms downstream of Eph receptors are unclear. Here we show that EphA receptors regulate prostate cancer cell dissemination in a 2D dispersal assay and in a 3D cancer cell spheroid assay. We show that EphA receptors signal via the exchange factor Vav2 to activate RhoA and that both Vav2 and RhoA are required for prostate cancer cell–cell repulsion. Furthermore, we find that in EphA2/EphA4, Vav2 or RhoA siRNA-treated cells, contact repulsion can be restored by partial microtubule destabilisation. We propose that EphA–Vav2–RhoA-mediated repulsion between contacting cancer cells at the tumour edge could enhance their local invasion away from the primary tumour.

Distinct c-Met activation mechanisms induce cell rounding or invasion through pathways involving integrins, RhoA and HIP1

Many carcinomas have acquired oncogenic mechanisms for activating c-Met, including c-Met overexpression and excessive autocrine or paracrine stimulation with hepatocyte growth factor (HGF). However, the biological outcome of c-Met activation through these distinct modes remains ambiguous. Here, we report that HGF-mediated c-Met stimulation triggers a mesenchymal-type collective cell invasion. By contrast, the overexpression of c-Met promotes cell rounding. Moreover, in a high-throughput siRNA screen that was performed using a library of siRNAs against putative regulators of integrin activity, we identified RhoA and the clathrin-adapter protein HIP1 as crucial c-Met effectors in these morphological changes. Transient RhoA activation was necessary for the HGF-induced invasion, whereas sustained RhoA activity regulated c-Met-induced cell rounding. In addition, c-Met-induced cell rounding correlated with the phosphorylation of filamin A and the downregulation of active cell-surface integrins. By contrast, a HIP1-mediated increase in β1-integrin turnover was required for the invasion triggered by HGF. Taken together, our results indicate that c-Met induces distinct cell morphology alterations depending on the stimulus that activates c-Met.

Eph receptors and ephrins as targets for cancer therapy

Eph receptor tyrosine kinases and their ephrin ligands are involved in various signalling pathways and mediate critical steps of a wide variety of physiological and pathological processes. Increasing experimental evidence demonstrates that both Eph receptor and ephrin ligands are overexpressed in a number of human tumours, and are associated with tumour growth, invasiveness and metastasis. In this regard, the Eph/ephrin system provides the foundation for potentially exciting new targets for anticancer therapies for Eph-expressing tumours. The purpose of this review is to outline current advances in the role of Eph receptors and ephrin ligands in cancer, and to discuss novel therapeutic approaches of anticancer therapies.

High levels of EphA3 expression are associated with high invasive capacity and poor overall survival in hepatocellular carcinoma

Although EphA3 expression has been associated with progression or prognosis in several types of tumors, the role of EphA3 in hepatocellular carcinoma (HCC) remains unknown. This study sought to investigate the clinicopathological and prognostic relevance of EphA3 expression in HCC as well as the underlying mechanisms responsible. EphA3 protein was mainly localized within the cytoplasm and at the cell membrane. High EphA3 expression was correlated with tumor size, tumor grade, metastasis, venous invasion and AJCC TNM stage (P<0.05), and patients with high levels of EphA3 expression were at a significantly increased risk for shortened survival time (P<0.05). In vitro, the downregulation of EphA3 expression decreased the invasive capacity of HCC cells via the regulation of VEGF. EphA3 may represent a novel candidate marker for patient prognosis as well a molecular target for HCC therapy.

Putative miRNAs for the diagnosis of dyslexia, dyspraxia, and specific language impairment

Disorders of human communication abilities can be classified into speech and language disorders. Speech disorders (e.g., dyspraxia) affect the sound generation and sequencing, while language disorders (e.g., dyslexia and specific language impairment, or SLI) are deficits in the encoding and decoding of language according to its rules (reading, spelling, grammar). The diagnosis of such disorders is often complicated, especially when a patient presents more than one disorder at the same time. The present review focuses on these challenges. We have combined data available from the literature with an in silico approach in an attempt to identify putative miRNAs that may have a key role in dyspraxia, dyslexia and SLI. We suggest the use of new miRNAs, which could have an important impact on the three diseases. Further, we relate those miRNAs to the axon guidance pathway and discuss possible interactions and the role of likely deregulated proteins. In addition, we describe potential differences in expressional deregulation and its role in the improvement of diagnosis. We encourage experimental investigations to test the data obtained in silico.