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Malaysia reported the first human case of Nipah virus (NiV) in late September 1998 with encephalitis and respiratory symptoms. As a result of viral genomic mutations, two main strains (NiV-Malaysia and NiV-Bangladesh) have spread around the world. There are no licensed molecular therapeutics available for this biosafety level 4 pathogen. NiV attachment glycoprotein plays a critical role in viral transmission through its human receptors (Ephrin-B2 and Ephrin-B3), so identifying small molecules that can be repurposed to inhibit them is crucial to developing anti-NiV drugs. Consequently, in this study annealing simulations, pharmacophore modeling, molecular docking, and molecular dynamics were used to evaluate seven potential drugs (Pemirolast, Nitrofurantoin, Isoniazid Pyruvate, Eriodictyol, Cepharanthine, Ergoloid, and Hypericin) against NiV-G, Ephrin-B2, and Ephrin-B3 receptors. Based on the annealing analysis, Pemirolast for efnb2 protein and Isoniazid Pyruvate for efnb3 receptor were repurposed as the most promising small molecule candidates. Furthermore, Hypericin and Cepharanthine, with notable interaction values, are the top Glycoprotein inhibitors in Malaysia and Bangladesh strains, respectively. In addition, docking calculations revealed that their binding affinity scores are related to efnb2-pem (− 7.1 kcal/mol), efnb3-iso (− 5.8 kcal/mol), gm-hyp (− 9.6 kcal/mol), gb-ceph (− 9.2 kcal/mol). Finally, our computational research minimizes the time-consuming aspects and provides options for dealing with any new variants of Nipah virus that might emerge in the future. [ABSTRACT FROM AUTHOR]

Ephrin B3, a member of Eph/ephrin family, contributes to embryogenesis and carcinogenesis, but few studies have suggested whether this ligand has regulatory effect on colitis. This study was to determine whether ephrin B3 played a role in colitis and colonic carcinogenesis. Dextran sodium sulfate (DSS)-induced colitis and azoxymethane (AOM)/DSS-induced colitis-associated carcinogenesis model was established in Efnb3-deficient (Efnb3 -/- ) mice. Label-free quantitative proteomics were performed to identify the Efnb3-regulated proteins. Our results showed that Efnb3 knock out reduced the symptoms of DSS-induced colitis, such as disease activity index (DAI), inflammatory factors release, and dysfunction of the intestinal barrier. Quantitative proteomics revealed that Efnb3 regulated 95 proteins which clustered in the platelet degranulation, response to elevated platelet cytosolic Ca 2+ , MAPK signaling for integrins such as ITGB4. Furthermore, ephrin B3 inactived ITGB4/AKT signal pathway and then promoted epithelial barrier dysfunction. Simultaneously, ephrin B3 promoted Gremlin-1/NF-κB signal pathway and thereby increased inflammatory factors release. In addition, the higher level of Efnb3 in colon cancer patients is correlated with worse survival. Efnb3 -/- mice exhibited susceptibility to AOM/DSS-induced colorectal cancer. Our finding discovered that Efnb3 played an important role in the development of colitis and colitis-associated colorectal cancer. Efnb3 deficiency improved the intestinal barrier by ITGB4 and suppressed inflammation via Gremlin-1/NF-κB signal pathway, which may provide a novel therapeutic strategy for the treatment of colitis and colitis-associated colorectal cancer., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Abstract The ephrin family of membrane proteins binds Eph tyrosine kinase receptors. We have previously shown that ephrin-B3 also binds to heparan sulfate proteoglycans (HSPGs). We now show that ephrin-B3 can bind both secretory and cell associated PGs, such as agrin, collagen XVIII, Perlecan, and CD44, and indicate that such interaction with cell associated PGs involves a complex including 20 and 45 kDa proteins. Ephrin-B3 binding to HEK-293T cells is blocked by a secretory variant of CD44 (v3-v10), while over-expression of membrane associated CD44 increased ephrin-B3 binding. In addition, ephrin-B3 precipitated CD44 expressed by the oral squamous carcinoma cell line H376. Moreover, ephrin-B3 binding affinities to heparin and CD44 in solution was strong. In conclusion, we have identified secretory and cell associated PGs with high ability to bind ephrin-B3 and suggest that ephrin-B3 can bind to a protein complex organized by a membrane associated PG. [ABSTRACT FROM AUTHOR]

The Paramyxoviridae genus Henipavirus is presently represented by the type species Hendra and Nipah viruses which are both recently emerged zoonotic viral pathogens responsible for repeated outbreaks associated with high morbidity and mortality in Australia, Southeast Asia, India and Bangladesh. These enveloped viruses bind and enter host target cells through the coordinated activities of their attachment (G) and class I fusion (F) envelope glycoproteins. The henipavirus G glycoprotein interacts with host cellular B class ephrins, triggering conformational alterations in G that lead to the activation of the F glycoprotein, which facilitates the membrane fusion process. Using the recently published structures of HeV-G and NiV-G and other paramyxovirus glycoproteins, we review the features of the henipavirus envelope glycoproteins that appear essential for mediating the viral fusion process, including receptor binding, G-F interaction, F activation, with an emphasis on G and the mutations that disrupt viral infectivity. Finally, recent candidate therapeutics for henipavirus-mediated disease are summarized in light of their ability to inhibit HeV and NiV entry by targeting their G and F glycoproteins.

The amygdala serves as emotional center to mediate innate fear behaviors that are reflected through neuronal responses to environmental aversive cues. However, the molecular mechanism underlying the initial neuron responses is poorly understood. In this study, we monitored the innate defensive responses to aversive stimuli of either elevated plus maze or predator odor in juvenile mice and found that glutamatergic neurons were activated in amygdala. Loss of EphB2, a receptor tyrosine kinase expressed in amygdala neurons, suppressed the reactions and led to defects in spine morphogenesis and fear behaviors. We further found a coupling of spinogenesis with these threat cues induced neuron activation in developing amygdala that was controlled by EphB2. A constitutively active form of EphB2 was sufficient to rescue the behavioral and morphological defects caused by ablation of ephrin-B3, a brain-enriched ligand to EphB2. These data suggest that kinase-dependent EphB2 intracellular signaling plays a major role for innate fear responses during the critical developing period, in which spinogenesis in amygdala glutamatergic neurons was involved. [ABSTRACT FROM AUTHOR]

Context: Gastric cancer (GC) remains one of the most prevalent malignancies worldwide, and no effective cure exists for advanced GC. Clinicians believe that molecularly targeted therapy through PCGs may replace surgery, radiotherapy, and other treatments as a breakthrough in curing malignancies., Objective: The study intended to examine the impact of aberrant expression of the protein-coding genes (PCGs) associated with regulatory T cells on the prognosis of patients with gastric cancer (GC)., Design: The research team performed a genetic study through research of genetic data in online databases., Setting: The study took place at Zhongda Hospital., Outcome Measures: The research team selected a publicly available dataset, genetic suppressor element 109476 (GSE109476), from the Gene Expression Omnibus (GEO) database for differential gene analysis, gene ontology (GO) analysis, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis to screen for PCGs associated with regulatory T cells as well as the Gene Expression Profiling Interactive Analysis (GEPIA) database with the Kaplan-Meier Plotter database to analyze the expression of the above PCGs in GC and the prognostic impact on GC., Results: The GEO2R analysis found 315 differentially expressed PCGs in GSE109476, among which nine PCGs were associated with regulatory T cells: (1) chemokine (C-C motif) ligand 19 (CCL19), (2) CCL21, (3) C-C chemokine receptor type 7 (CCR7), (4) cluster of differentiation 70 (CD70), (5) ephrin B3 (EFNB3), (6) early growth response 3 (EGR3), (7) interleukin-7 receptor (IL7R), (8) galectin-1 (LGALS1), and (9) tumor necrosis factor (TNF) receptor superfamily member 13C (TNFRSF13C). The GEPIA database indicated that no significant differences existed between the expression of CCL19, CCL21, CD70, EFNB3, EGR3, IL7R, and TNFRSF13C in stomach adenocarcinoma (STAD) tissues and that in normal tissues (P > .05), while expressions of CCR7 and LGALS1 were significantly elevated in STAD tissues compared to the normal tissues (P < .05). The Kaplan-Meier Plotter database analysis, on the other hand, showed a significant relationship between all of the above-mentioned PCGs, except CCL19, and the prognosis of GC., Conclusions: CCL19, CCL21, CCR7, CD70, EFNB3, EGR3, IL7R, LGALS1, and TNFRSF13C are PCGs are differentially expressed in GC and closely associated with regulatory T cells. They may affect the occurrence and development of GC through a variety of pathways, including regulation of immune infiltration and inflammation, and are of great potential research value.

Eph-ephrin signaling is known to be important in directing topographic projections in the afferent auditory pathway, including connections to various subdivisions of the inferior colliculus (IC). The acoustic startle-response (ASR) is a reliable reflexive behavioral response in mammals elicited by an unexpected intense acoustic startle-eliciting stimulus (ES). It is mediated by a sub-cortical pathway that includes the IC. The ASR amplitude can be measured with an accelerometer under the subject and can be decreased in amplitude by presenting a less intense, non-startling stimulus 5-300ms before the ES. This reflexive decrement in ASR is called pre-pulse inhibition (PPI) and indicates that the relatively soft pre-pulse was heard. PPI is a general trait among mammals. Mice have been used recently to study this response and to reveal how genetic mutations affect neural circuits and hence the ASR and PPI. In this experiment, we measured the effect of Eph-ephrin mutations using control mice (C57BL/6J), mice with compromised EphA4 signaling (EphA4lacZ/+, EphA4lacZ/lacZ), and knockout ephrin-B3 mice (ephrin-B3 +/−, −/−). Control and EphA4lacZ/+strains showed robust PPI (up to 75% decrement in ASR) to an offset of a 70dB SPL background noise at 50ms before the ES. Ephrin-B3 knockout mice and EphA4 homozygous mutants were only marginally significant in PPI (<25% decrement and <33% decrement, respectively) to the same conditions. This decrement in PPI highlights the importance of ephrin-B3 and EphA4 interactions in ordering auditory behavioral circuits. Thus, different mutations in certain members of the signaling family produce a full range of changes in PPI, from minimal to nearly maximal. This technique can be easily adapted to study other aspects of hearing in a wider range of mutations. Along with ongoing neuroanatomical studies, this allows careful quantification of how the auditory anatomical, physiological and now behavioral phenotype is affected by changes in Eph-ephrin expression and functionality. [ABSTRACT FROM AUTHOR]

Hu sheep, a famous breed in the Taihu Basin, has the advantages of non-seasonal estrus, multiple fetuses, coarse feeding tolerance, and suitability for house feeding. Runs of homozygosity (ROHs) were found to be an effective tool to detect the animal population structure and economic traits. The detection of ROHs is beneficial for reducing the incidence of inbreeding as well as identifying harmful variants in the genome. However, there is a lack of systemic reports on ruminants in previous studies of ROHs. Here, we sequenced 108 Hu sheep, detected ROHs in Hu sheep to calculate their inbreeding coefficient, and selected genes of Hu sheep breeds within the ROH islands which are relevant to agricultural economic characteristics. Then, we compared the characteristics of the occurrences of SNPs between Hu sheep and other sheep breeds, and also investigated the distribution of the frequencies of SNPs within specific gene regions of Hu sheep breeds to select their breed-specific genes. Furthermore, we performed a comparative genome and transcriptome analysis in human and sheep breeds to identify important reproduction-related genes. In this way, we found some significant SNPs, and mapped these with a set of interesting candidate genes which are related to the productive value of livestock ( FGF9 , BMPR1B , EFNB3 , MICU2 , GFRA3 ), healthy characteristics ( LGSN , EPHA5 , ALOX15B ), and breed specificity ( FGF9 , SAP18 , MICU2 ). These results in our study describe various production traits of Hu sheep from a genetic perspective, and provide insights into the genetic management and complementary understanding of Hu sheep.

The Paramyxoviridae genus Henipavirus is presently represented by the type species Hendra and Nipah viruses which are both recently emerged zoonotic viral pathogens responsible for repeated outbreaks associated with high morbidity and mortality in Australia, Southeast Asia, India and Bangladesh. These enveloped viruses bind and enter host target cells through the coordinated activities of their attachment (G) and class I fusion (F) envelope glycoproteins. The henipavirus G glycoprotein interacts with host cellular B class ephrins, triggering conformational alterations in G that lead to the activation of the F glycoprotein, which facilitates the membrane fusion process. Using the recently published structures of HeV-G and NiV-G and other paramyxovirus glycoproteins, we review the features of the henipavirus envelope glycoproteins that appear essential for mediating the viral fusion process, including receptor binding, G-F interaction, F activation, with an emphasis on G and the mutations that disrupt viral infectivity. Finally, recent candidate therapeutics for henipavirus-mediated disease are summarized in light of their ability to inhibit HeV and NiV entry by targeting their G and F glycoproteins. [ABSTRACT FROM AUTHOR]

Cerebral ischemia stimulates endogenous neurogenesis. However, the functional relevance of this phenomenon remains unclear because of poor survival and low neuronal differentiation rates of newborn cells. Therefore, further studies on mechanisms regulating neurogenesis under ischemic conditions are required, among which ephrin-ligands and ephrin-receptors (Eph) are an interesting target. Although Eph/ephrin proteins like ephrin-B3 are known to negatively regulate neurogenesis under physiological conditions, their role in cerebral ischemia is largely unknown. We therefore studied neurogenesis, brain injury and functional outcome in ephrin-B3 (knockout) and ephrin-B3 (wild-type) mice submitted to cerebral ischemia. Induction of stroke resulted in enhanced cell proliferation and neuronal differentiation around the lesion site of ephrin-B3 compared to ephrin-B3 mice. However, prominent post-ischemic neurogenesis in ephrin-B3 mice was accompanied by significantly increased ischemic injury and motor coordination deficits that persisted up to 4 weeks. Ischemic injury in ephrin-B3 mice was associated with a caspase-3-dependent activation of the signal transducer and activator of transcription 1 (STAT1). Whereas inhibition of caspase-3 had no effect on brain injury in ephrin-B3 animals, infarct size in ephrin-B3 mice was strongly reduced, suggesting that aggravated brain injury in these animals might involve a caspase-3-dependent activation of STAT1. In conclusion, post-ischemic neurogenesis in ephrin-B3 mice is strongly enhanced, but fails to contribute to functional recovery because of caspase-3-mediated aggravation of ischemic injury in these animals. Our results suggest that ephrin-B3 might be an interesting target for overcoming some of the limitations of further cell-based therapies in stroke. [ABSTRACT FROM AUTHOR]

Abstract: The fibers of corticospinal tract (CST), which control fine motor function, predominantly project to the contralateral spinal cord, not recross to the ipsilateral side. Ephrin-B3, which is expressed in the midline of the spinal cord, and its receptor, EphA4, are crucial for preventing CST fibers from recrossing the midline in the developing spinal cord. However, these fibers can cross the midline to the denervated side after a unilateral CST or cortical injury. We determined the reason CST fibers can cross the midline after a cortical injury and the changes in ephrin-B3–EphA4 signaling associated with such a crossing. We first examined axonal sprouting from CST fibers after unilateral ablation of the motor cortex in postnatal and adult mice. CST fibers crossed the midline of the spinal cord after cortical ablation, especially when conducted during the early postnatal period. These fibers were well associated with functional recovery after the injury. We next assessed the mRNA expression of ephrin-B3 and EphA4 before and after the ablation. Surprisingly, no changes were detected in the expression patterns. We found, however, that ephrin-B3 expression in the ventral part of the midline disappeared after postnatal day 9 (P9), but was pronounced along the entire midline before P6. Most of the CST fibers crossed the midline through the ventral region, where ephrin-B3 expression was absent. Our results suggest that ephrin-B3 is not expressed along the entire midline of the spinal cord, and sprouting axons can cross the midline at ephrin-B3-negative areas. [Copyright &y& Elsevier]

Abstract: B-ephrin–EphB receptor signaling modulates NMDA receptors by inducing tyrosine phosphorylation of NR2 subunits. Ephrins and EphB RTKs are localized to postsynaptic compartments in the CA1, and therefore potentially interact in a non-canonical cis- configuration. However, it is not known whether cis- configured receptor–ligand signaling is utilized by this class of RTKs, and whether this might influence excitatory synapses. We found that ablation of ephrin-B3 results in an enhancement of the NMDA receptor component of synaptic transmission relative to the AMPA receptor component in CA1 synapses. Synaptic AMPA receptor expression is reduced in ephrin-B3 knockout mice, and there is a marked enhancement of tyrosine phosphorylation of the NR2B receptor subunit. In a reduced system co-expression of ephrin-B3 attenuated EphB2-mediated NR2B tyrosine phosphorylation. Moreover, phosphorylation of EphB2 was elevated in the hippocampus of ephrin-B3 knockout mice, suggesting that regulation of EphB2 activity is lost in these mice. Direct activation of EphB RTKs resulted in phosphorylation of NR2B and a potential signaling partner, the non-receptor tyrosine kinase Pyk2. Our data suggests that ephrin-B3 limits EphB RTK-mediated phosphorylation of the NR2B subunit through an inhibitory cis- interaction which is required for the correct function of glutamatergic CA1 synapses. [ABSTRACT FROM AUTHOR]

Abstract: Hendra virus (HeV) and Nipah virus (NiV) are closely related paramyxoviruses that infect and cause disease in a wide range of mammalian hosts. To determine whether host receptor molecules play a role in species-specific and/or virus-specific infection we have cloned and characterized ephrin-B2 and ephrin-B3 ligands from a range of species, including human, horse, pig, cat, dog, bats (Pteropus alecto and Pteropus vampyrus) and mouse. HeV and NiV were both able to infect cells expressing any of the ephrin-B2 and ephrin-B3 molecules. There did not appear to be significant differences in receptor function from different species or receptor usage by HeV and NiV. Soluble ephrin ligands, their receptors and G-specific human monoclonal antibodies differentially blocked henipavirus infections suggesting different receptor affinities, overlapping receptor binding domains of the henipavirus attachment glycoprotein (G) and that the functional domains of the ephrin ligands may be important for henipavirus binding. [Copyright &y& Elsevier]

Abstract: EphB receptor tyrosine kinases and ephrin-B ligands regulate several types of cell–cell interactions during brain development, generally by modulating the cytoskeleton. EphB/ephrinB genes are expressed in the developing neural tube of early mouse embryos with distinct overlapping expression in the ventral midbrain. To test EphB function in midbrain development, mouse embryos compound homozygous for mutations in the EphB2 and EphB3 receptor genes were examined for early brain phenotypes. These mutants displayed a morphological defect in the ventral midbrain, specifically an expanded ventral midline evident by embryonic day E9.5–10.5, which formed an abnormal protrusion into the cephalic flexure. The affected area was comprised of cells that normally express EphB2 and ephrin-B3. A truncated EphB2 receptor caused a more severe phenotype than a null mutation, implying a dominant negative effect through interference with EphB forward (intracellular) signaling. In mutant embryos, the overall number, size, and identity of the ventral midbrain cells were unaltered. Therefore, the defect in ventral midline morphology in the EphB2;EphB3 compound mutant embryos appears to be caused by cellular changes that thin the tissue, forcing a protrusion of the ventral midline into the cephalic space. Our data suggests a role for EphB signaling in morphological organization of specific regions of the developing neural tube. [Copyright &y& Elsevier]

Axons travel frequently in bundles to reach their target. After arriving at the target, axon terminals defasciculate, migrate to topographically defined positions, and form synapses with appropriate target neurons. Here we present evidence that the B-type receptors of the erythropoietin-producing hepatocellular (Eph) family and a ligand, ephrin-B3, influence hippocampal axon defasciculation. The EphB receptors are expressed in the hippocampus, and the ligand, ephrin-B3, is transcribed in the lateral septum, the major subcortical target ofhippocampal neurons. Ephrin-B3 promotes adhesion of hippocampal neurons to the ligand-expressing substrates in vitro, and the loss of the receptor EphB2 abrogates the effects of ephrin-B3. In mice deficient in EphB2 and EphB3, many hippocampal axons remain in bundles. This phenotype was also observed in mice that were specifically deleted for the cytoplasmic domain of EphB2. These observations indicate that the EphB receptors and their ligand regulate hippocampal axon defasciculation at the septal target, possibly through a receptor-mediated forward signaling mechanism. [ABSTRACT FROM AUTHOR]

Abstract The role was studied of ephrin-B3, a ligand of the Eph family of tyrosine kinase receptors, in the formation of cortical connectivity. In situ hybridization and immunohistochemistry showed that EphA4, a receptor of ephrin-B3, was expressed in the lateral thalamus (visual and somaotosensory thalamus) of the developing rat brain, but not in the medial thalamic nuclei which project to the limbic cortex. Correspondingly, ephrin-B3 was expressed strongly in the developing limbic cortex including amygdala, entorhinal cortex and hippocampus. To examine the action of ephrin-B3 on thalamic axons, either lateral or medial thalamic explants were cultured on membranes obtained from ephrin-B3-expressing COS cells. Axonal growth was inhibited for cells from the lateral thalamus but not from the medial thalamus. These results suggest that ephrin-B3 contributes to regional specificity by suppressing axonal growth of lateral thalamic neurons. [ABSTRACT FROM AUTHOR]

Background: The molecular mechanisms underlying malignancy of osteosarcoma are unknown. It has been reported that eph receptor protein tyrosine kinases and their ligands, ephrins, are associated with increased tumorigenicity in patients with breast carcinoma and melanoma. The expression and role of eph/ephrins in human osteosarcoma has not yet been characterized., Methods: Ephrin-A1, ephrin-A3, ephrin-A4, ephrin-A5, ephrin-B1, ephrin-B2, and ephrin-B3 mRNA expression was examined by reverse transcription polymerase chain reaction analysis in nine specimens of human osteosarcoma tissue and five human osteosarcoma cell lines. Ephrin-B1 protein expression was detected immunohistochemically in human osteosarcoma tissue. Clinicopathologic correlation was made between the osteosarcoma specimens and their ephrin expression profiles., Results: Normal bone specimens, osteosarcoma tissue specimens, and osteosarcoma cell lines expressed a distinct mRNA profile of ephrin-A1, ephrin-A4, and ephrin-B2. A second mRNA profile that included ephrin-A3, ephrin-A5, and ephrin-B1 was expressed by a subset of tumors. The expression of ephrin-B1 was correlated with a poorer clinical prognosis. Ephrin-B1 protein was expressed by osteosarcoma cells and blood vessels., Conclusions: The results of this study suggest that ephrin-B1 expressed by osteosarcoma may be a poor prognostic marker through increased tumorigenicity., (Copyright 2002 American Cancer Society.DOI 10.1002/cncr.10749)

We report that EphB receptors direct unique axonal behaviors required for mapping the dorsal-ventral (D-V) retinal axis along the lateral-medial (L-M) axis of the superior colliculus (SC). EphBs are expressed in a D-V gradient, ephrin-B1 in a L-M gradient in SC, and ephrin-B3 at its midline. EphBs and ephrin-Bs are expressed in countergradients in retina and SC. Developmental analyses reveal that retinal axons lack D-V ordering along the L-M axis, but directionally extend branches along it to establish ordered arbors. Directed branch extension is disrupted in EphB2; EphB3-deficient mice resulting in lateral ectopic arbors. Mice with kinase-inactive EphB2 have similar D-V mapping defects indicating that forward signaling dominates over reverse signaling. Our data suggest that branches of EphB expressing axons are attracted medially by ephrin-B1, and provide molecular mechanisms for D-V mapping in visual centers.

Background: The erythropoietin-producing hepatoma amplified sequence (Eph) family is the largest subfamily of receptor tyrosine kinases (RTKs). The Ephs (receptors) bind to specific cell-bound ligands, called ephrins. The binding of this ligand-receptor system is dependent on cell-cell interactions. The ephrin-Eph system is important in embryologic development and differentiation of the nervous and vascular systems. In the current study, the authors hypothesized that ephrins may play a role in the growth and development of colon carcinoma and may be expressed differentially in normal and malignant colonic tissues., Methods: Reverse transcriptase-polymerase chain reaction (RT-PCR), Northern Blot analyses, and immunohistochemistry were used to examine 11 colon carcinoma cell lines and 20 human colon carcinoma specimens with adjacent uninvolved mucosa for the expression of EphB and ephrin-B family members., Results: EphB2, EphB3, and EphB4 mRNA expression and ephrin-B2 mRNA expression was detected in all the cell lines and colon carcinoma specimens examined. Immunohistochemical analysis showed that ephrin-B2 had higher expression in the colon carcinoma specimens studied than in adjacent normal mucosa. Ephrin-B2 and EphB4 most frequently were expressed on the luminal surface of colon carcinoma epithelium., Conclusions: The results of the current suggest that the ephrin-Bs are expressed differentially in colon carcinoma and normal mucosa specimens and thus may play a role in the progression of colon carcinoma. Further studies are necessary to determine the functional role of ephrin-Bs in colon carcinoma angiogenesis and growth., (Copyright 2002 American Cancer Society. DOI 10.1002/cncr.10122)

During development, Eph receptors mediate the repulsive axon guidance function of ephrins, a family of membrane attached ligands with their own receptor-like signaling potential. In cultured glutamatergic neurons, EphB2 receptors were recently shown to associate with NMDA receptors at synaptic sites and were suggested to play a role in synaptogenesis. Here we show that Eph receptor stimulation in cultured neurons modulates signaling pathways implicated in synaptic plasticity, suggesting cross-talk with NMDA receptor-activated pathways. Mice lacking EphB2 have normal hippocampal synapse morphology, but display defects in synaptic plasticity. In EphB2(-/-) hippocampal slices, protein synthesis-dependent long-term potentiation (LTP) was impaired, and two forms of synaptic depression were completely extinguished. Interestingly, targeted expression of a carboxy-terminally truncated form of EphB2 rescued the EphB2 null phenotype, indicating that EphB2 kinase signaling is not required for these EphB2-mediated functions.

The Eph family of receptor tyrosine kinases and their ligands, the ephrins, are important regulators of axon guidance and cell migration in the developing nervous system. Inactivation of the EphA4 gene results in axon guidance defects of the corticospinal tract, a major descending motor pathway that originates in the cortex and terminates at all levels of the spinal cord. In this investigation, we report that although the initial development of the corticospinal projection is normal through the cortex, internal capsule, cerebral peduncle, and medulla in the brain of EphA4 deficient animals, corticospinal axons exhibit gross abnormalities when they enter the gray matter of the spinal cord. Notably, many corticospinal axons fail to remain confined to one side of the spinal cord during development and instead, aberrantly project across the midline, terminating ipsilateral to their cells of origin. Given the possible repulsive interactions between EphA4 and one of its ligands, ephrinB3, this defect could be consistent with a loss of responsiveness by corticospinal axons to ephrinB3 that is expressed at the spinal cord midline. Furthermore, we show that EphA4 deficient animals exhibit ventral displacement of the mature corticospinal termination pattern, suggesting that developing corticospinal axons, which may also express ephrinB3, fail to be repelled from areas of high EphA4 expression in the intermediate zone of the normal spinal cord. Taken together, these results suggest that the dual expression of EphA4 on corticospinal axons and also within the surrounding gray matter is very important for the correct development and termination of the corticospinal projection within the spinal cord., (Copyright 2001 Wiley-Liss, Inc.)

To identify molecules involved in neurogenesis, we have raised monoclonal antibodies against embryonic day 12.5 mouse telencephalon. One antibody, monoclonal antibody 25H11, stains predominantly the ventricular zone of the anterior and lateral telencephalon. Purification of the 25H11 antigen, a 47 kDa integral membrane protein, from approximately 2500 mouse telencephali reveals its identity with ephrin B1. Ephrin B1 appears at the onset of neocortical neurogenesis, being first expressed in neuron-generating neuroepithelial cells and rapidly thereafter in virtually all neuroepithelial cells. Expression of ephrin B1 persists through the period of neocortical neurogenesis and is downregulated thereafter. Ephrin B1 is present on the ventricular as well as basolateral plasma membrane of neuroepithelial cells and exhibits an ventricular-high to pial-low gradient across the ventricular zone. Expression of ephrin B1 is also detected on radial glial cells, extending all the way to their pial endfeet, and on neurons in the mantle/intermediate zone but not in the cortical plate. Our results suggest that ephrin B1, presumably via ephrin-Eph receptor signaling, has a role in neurogenesis. Given the ventricular-to-pial gradient of ephrin B1 on the neuroepithelial cell surface and its known role in cell migration in other systems mediated by its repulsive properties, we propose that ephrin B1 may be involved in the migration of newborn neurons out from the ventricular zone toward the neocortex.

Growing axons follow highly stereotypical pathways, guided by a variety of attractive and repulsive cues, before establishing specific connections with distant targets. A particularly well-known example that illustrates the complexity of axonal migration pathways involves the axonal projections of motor neurons located in the motor cortex. These projections take a complex route during which they first cross the midline, then form the corticospinal tract, and ultimately connect with motor neurons in the contralateral side of the spinal cord. These obligatory contralateral connections account for why one side of the brain controls movement on the opposing side of the body. The netrins and slits provide well-known midline signals that regulate axonal crossings at the midline. Herein we report that a member of the ephrin family, ephrin-B3, also plays a key role at the midline to regulate axonal crossing. In particular, we show that ephrin-B3 acts as the midline barrier that prevents corticospinal tract projections from recrossing when they enter the spinal gray matter. We report that in ephrin-B3(-/-) mice, corticospinal tract projections freely recross in the spinal gray matter, such that the motor cortex on one side of the brain now provides bilateral input to the spinal cord. This neuroanatomical abnormality in ephrin-B3(-/-) mice correlates with loss of unilateral motor control, yielding mice that simultaneously move their right and left limbs and thus have a peculiar hopping gait quite unlike the alternate step gait displayed by normal mice. The corticospinal and walking defects in ephrin-B3(-/-) mice resemble those recently reported for mice lacking the EphA4 receptor, which binds ephrin-B3 as well as other ephrins, suggesting that the binding of EphA4-bearing axonal processes to ephrin-B3 at the midline provides the repulsive signal that prevents corticospinal tract projections from recrossing the midline in the developing spinal cord.

To investigate Eph-ephrin bidirectional signaling, a series of mutations were generated in the ephrin-B3 locus. The absence of both forward and reverse signaling resulted in mice with mirror movements as typified by a hopping locomotion. The corticospinal tract was defective as axons failed to respect the midline boundary of the spinal cord and bilaterally innervated both contralateral and ipsilateral motor neuron populations. A second mutation that expresses a truncated ephrin-B3 protein lacking its cytoplasmic domain did not lead to hopping, indicating that reverse signaling is not required for corticospinal innervation. Ephrin-B3 is concentrated at the spinal cord midline, while one of its receptors, EphA4, is expressed in postnatal corticospinal neurons as their fibers pathfind down the contralateral spinal cord. Our data indicate ephrin-B3 functions as a midline-anchored repellent to stimulate forward signaling in EphA4-expressing axons.

Background: EPH family receptor tyrosine kinases and their ligand ephrins play pivotal roles in development. High-level expression of transcripts encoding EPHB6 receptors (EPHB6), its ligands ephrin-B2 and ephrin-B3 (EFNB2, EFNB3) is predictive of favorable disease outcome of neuroblastoma (NB). When combined with TrkA expression, the expression of EPHB6, EFNB2, or EFNB3 predicts more accurately the disease outcome than each of the four variables alone., Procedure: Cox regression and Kaplan-Meier analyses were used to assess the prognostic significance of EPHB6, EFNB2, EFNB3, and TrkA expressions in NB without MYCN amplification., Results: High-level expression of EFNB3 or TrkA predicted favorable NB outcome of NB without MYCN amplification (p < 0.03). As found in the general NB population, EPHB6, EFNB2, or EFNB3 expression in combination with TrkA expression was significantly predictive of the disease outcome of normal MYCN NB (p < 0.01)., Conclusions: EPHB6, EFNB2, and EFNB3 expressions may permit further refinement of the prognostic stratification of NB into favorable and unfavorable groups., (Copyright 2000 Wiley-Liss, Inc.)

The cues and signaling systems that guide the formation of embryonic blood vessels in tissues and organs are poorly understood. Members of the Eph family of receptor tyrosine kinases and their cell membrane-anchored ligands, the ephrins, have been assigned important roles in the control of cell migration during embryogenesis, particularly in axon guidance and neural crest migration. Here we investigated the role of EphB receptors and their ligands during embryonic blood vessel development in Xenopus laevis. In a survey of tadpole-stage Xenopus embryos for EphB receptor expression, we detected expression of EphB4 receptors in the posterior cardinal veins and their derivatives, the intersomitic veins. Vascular expression of other EphB receptors, including EphB1, EphB2 or EphB3, could however not be observed, suggesting that EphB4 is the principal EphB receptor of the early embryonic vasculature of Xenopus. Furthermore, we found that ephrin-B ligands are expressed complementary to EphB4 in the somites adjacent to the migratory pathways taken by intersomitic veins during angiogenic growth. We performed RNA injection experiments to study the function of EphB4 and its ligands in intersomitic vein development. Disruption of EphB4 signaling by dominant negative EphB4 receptors or misexpression of ephrin-B ligands in Xenopus embryos resulted in intersomitic veins growing abnormally into the adjacent somitic tissue. Our findings demonstrate that EphB4 and B-class ephrins act as regulators of angiogenesis possibly by mediating repulsive guidance cues to migrating endothelial cells.