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

Eph receptors and their ephrin ligands are viewed as promising targets for cancer treatment; however, targeting them is hindered by their context-dependent functionalities. To circumvent this, we explore molecular landscapes underlying their pro- and anti-malignant activities. Using unbiased bioinformatics approaches, we construct a cancer-related network of genetic interactions (GIs) of all Ephs and ephrins to assist in their therapeutic manipulation.

A Multipronged Unbiased Strategy Guides the Development of an Anti-EGFR/EPHA2-Bispecific Antibody for Combination Cancer Therapy.

Purpose: Accumulating analyses of pro-oncogenic molecular mechanisms triggered a rapid development of targeted cancer therapies. Although many of these treatments produce impressive initial responses, eventual resistance onset is practically unavoidable. One of the main approaches for preventing this refractory condition relies on the implementation of combination therapies.

The Ephb2 Receptor Uses Homotypic, Head-to-Tail Interactions within Its Ectodomain as an Autoinhibitory Control Mechanism.

The Eph receptor tyrosine kinases and their ephrin ligands direct axon pathfinding and neuronal cell migration, as well as mediate many other cell-cell communication events. Their dysfunctional signaling has been shown to lead to various diseases, including cancer. The Ephs and ephrins both localize to the plasma membrane and, upon cell-cell contact, form extensive signaling assemblies at the contact sites.

Ephrin-A1 and the sheddase ADAM12 are upregulated in COVID-19.

More than 3.5 million people have died globally from COVID-19, yet an effective therapy is not available. It is, therefore, important to understand the signaling pathways that mediate disease progression in order to identify new molecular targets for therapeutic development.

Structure of the EphB6 receptor ectodomain.

Eph receptors are the largest group amongst the receptor tyrosine kinases and are divided into two subgroups, A and B, based on ligand binding specificities and sequence conservation. Through ligand-induced and ligand-independent activities, Ephs play central roles in diverse biological processes, including embryo development, regulation of neuronal signaling, immune responses, vasculogenesis, as well as tumor initiation, progression, and metastasis. The Eph extracellular regions (ECDs) are constituted of multiple domains, and previous structural studies of the A class receptors revealed how they interact with ephrin ligands and simultaneously mediate Eph-Eph clustering necessary for biological activity.

ADAM proteases: Emerging role and targeting of the non-catalytic domains.

ADAM proteases are multi domain transmembrane metalloproteases that cleave a range of cell surface proteins and activate signaling pathways implicated in tumor progression, including those mediated by Notch, EFGR, and the Eph receptors. Consequently, they have emerged as key therapeutic targets in the efforts to inhibit tumor initiation and progression. To that end, two main approaches have been taken to develop ADAM antagonists: (i) small molecule inhibitors, and (ii) monoclonal antibodies.

Therapeutic potential of targeting the Eph/ephrin signaling complex.

The Eph-ephrin signaling pathway mediates developmental processes and the proper functioning of the adult human body. This distinctive bidirectional signaling pathway includes a canonical downstream signal cascade inside the Eph-bearing cells, as well as a reverse signaling in the ephrin-bearing cells. The signaling is terminated by ADAM metalloproteinase cleavage, internalization, and degradation of the Eph/ephrin complexes.

Binding of EphrinA5 to RET receptor tyrosine kinase: An in vitro study.

Eph/Ephrin signaling pathways are crucial in regulating a large variety of physiological processes during development, such as cell morphology, proliferation, migration and axonal guidance. EphrinA (efn-A) ligands, in particular, can be activated by EphA receptors at cell-cell interfaces and have been proposed to cause reverse signaling via RET receptor tyrosine kinase. Such association has been reported to mediate spinal motor axon navigation, but conservation of the interactive signaling pathway and the molecular mechanism of the interaction are unclear.

Homotypic receptor-receptor interactions regulating Eph signaling.

The Eph receptor tyrosine kinases and their ephrin ligands direct axon pathfinding and neuronal cell migration, and mediate many other cell-cell communication events. The Ephs and ephrins both localize to the plasma membrane and, upon cell-cell contact, form extensive signaling assemblies at the contact sites. Recent structural, biochemical and cell-biological studies revealed that these assemblies are generated not only via Eph-ephrin interactions, but also via homotypic interactions between neighboring receptor molecules.

Generation and characterization of a single-chain anti-EphA2 antibody.

Recombinant antibody phage library technology provides multiple advantages, including that human antibodies can be generated against proteins that are highly conserved between species. We used this technology to isolate and characterize an anti-EphA2 single-chain antibody. We show that the antibody binds the antigen with 1:1 stoichiometry and has high specificity for EphA2.

Tie2 and Eph receptor tyrosine kinase activation and signaling.

The Eph and Tie cell surface receptors mediate a variety of signaling events during development and in the adult organism. As other receptor tyrosine kinases, they are activated on binding of extracellular ligands and their catalytic activity is tightly regulated on multiple levels. The Eph and Tie receptors display some unique characteristics, including the requirement of ligand-induced receptor clustering for efficient signaling.

Insights into Eph receptor tyrosine kinase activation from crystal structures of the EphA4 ectodomain and its complex with ephrin-A5.

Eph receptor tyrosine kinases and their ephrin ligands mediate cell signaling during normal and oncogenic development. Eph signaling is initiated in a multistep process leading to the assembly of higher-order Eph/ephrin clusters that set off bidirectional signaling in interacting cells. Eph and ephrins are divided in two subclasses based on their abilities to bind and activate each other and on sequence conservation.

Biological and structural characterization of glycosylation on ephrin-A1, a preferred ligand for EphA2 receptor tyrosine kinase.

The EphA2 receptor tyrosine kinase is overexpressed in a number of malignancies and is activated by ephrin ligands, most commonly by ephrin-A1. The crystal structure of the ligand-receptor complex revealed a glycosylation on the Asn-26 of ephrin-A1. Here we report for the first time the significance of the glycosylation in the biology of EphA2 and ephrin-A1.

Eph/ephrin recognition and the role of Eph/ephrin clusters in signaling initiation.

The Eph receptors and their ephrin ligands play crucial roles in a large number of cell-cell interaction events, including those associated with axon pathfinding, neuronal cell migration and vasculogenesis. They are also involved in the patterning of most tissues and overall cell positioning in the development of the vertebrate body plan. The Eph/ephrin signaling system manifests several unique features that differentiate it from other receptor tyrosine kinases, including initiation of bi-directional signaling cascades and the existence of ligand and receptor subclasses displaying promiscuous intra-subclass interactions, but very rare inter-subclass interactions.

Ectodomain structures of Eph receptors.

Eph receptors, the largest subfamily of receptor tyrosine kinases (RTKs), and their ephrin ligands are important mediators of cell-cell communication that regulate axon guidance, long-term potentiation, and stem cell development, among others. By now, many Eph receptors and ephrins have also been found to play important roles in the progression of cancer. Since both the receptor and the ligand are membrane-bound, their interaction leads to the multimerization of both molecules to distinct clusters within their respective plasma membranes, resulting in the formation of discrete signaling centers.

The Eph-receptor A7 is a soluble tumor suppressor for follicular lymphoma.

Insights into cancer genetics can lead to therapeutic opportunities. By cross-referencing chromosomal changes with an unbiased genetic screen we identify the ephrin receptor A7 (EPHA7) as a tumor suppressor in follicular lymphoma (FL). EPHA7 is a target of 6q deletions and inactivated in 72% of FLs.

A semisynthetic Eph receptor tyrosine kinase provides insight into ligand-induced kinase activation.

We have developed a methodology for generating milligram amounts of functional Eph tyrosine kinase receptor using the protein engineering approach of expressed protein ligation. Stimulation with ligand induces efficient autophosphorylation of the semisynthetic Eph construct. The in vitro phosphorylation of key Eph tyrosine residues upon ligand-induced activation was monitored via time-resolved, quantitative phosphoproteomics, suggesting a precise and unique order of phosphorylation of the Eph tyrosines in the kinase activation process.

Crystal structure of the Nogo-receptor-2.

The inhibition of axon regeneration upon mechanical injury is dependent on interactions between Nogo receptors (NgRs) and their myelin-derived ligands. NgRs are composed of a leucine-rich repeat (LRR) region, thought to be structurally similar among the different isoforms of the receptor, and a divergent "stalk" region. It has been shown by others that the LRR and stalk regions of NgR1 and NgR2 have distinct roles in conferring binding affinity to the myelin associated glycoprotein (MAG) in vivo.

Crystal structure of the ligand-binding domain of the promiscuous EphA4 receptor reveals two distinct conformations.

Eph receptors and their ephrin ligands are important mediators of cell-cell communication. They are divided in two subclasses based on their affinities for each other and on sequence conservation. Receptor-ligand binding within each subclass is fairly promiscuous, while binding cross the subclasses happens rarely.

Architecture of Eph receptor clusters.

Eph receptor tyrosine kinases and their ephrin ligands regulate cell navigation during normal and oncogenic development. Signaling of Ephs is initiated in a multistep process leading to the assembly of higher-order signaling clusters that set off bidirectional signaling in interacting cells. However, the structural and mechanistic details of this assembly remained undefined.

Ligand recognition by A-class Eph receptors: crystal structures of the EphA2 ligand-binding domain and the EphA2/ephrin-A1 complex.

Ephrin (Eph) receptor tyrosine kinases fall into two subclasses (A and B) according to preferences for their ephrin ligands. All published structural studies of Eph receptor/ephrin complexes involve B-class receptors. Here, we present the crystal structures of an A-class complex between EphA2 and ephrin-A1 and of unbound EphA2.

Host cell recognition by the henipaviruses: crystal structures of the Nipah G attachment glycoprotein and its complex with ephrin-B3.

Nipah virus (NiV) and Hendra virus are the type species of the highly pathogenic paramyxovirus genus Henipavirus, which can cause severe respiratory disease and fatal encephalitis infections in humans, with case fatality rates approaching 75%. NiV contains two envelope glycoproteins, the receptor-binding G glycoprotein (NiV-G) that facilitates attachment to host cells and the fusion (F) glycoprotein that mediates membrane merger. The henipavirus G glycoproteins lack both hemagglutinating and neuraminidase activities and, instead, engage the highly conserved ephrin-B2 and ephrin-B3 cell surface proteins as their entry receptors.

Toward the semisynthesis of multidomain transmembrane receptors: modification of Eph tyrosine kinases.

Expressed protein ligation (EPL) is a protein engineering approach that allows the modification or assembly of a target protein from multiple recombinant and synthetic polypeptides. EPL has been previously used to modify intracellular proteins and small integral membrane proteins for structural and functional studies. Here we describe the semisynthetic site-specific modification of the complete, multidomain extracellular regions of both A and B classes of Eph receptor tyrosine kinases.

The structure of apo tryptophanase from Escherichia coli reveals a wide-open conformation.

The crystal structure of apo tryptophanase from Escherichia coli (space group F222, unit-cell parameters a = 118.4, b = 120.1, c = 171.