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

Deo R Singh,Kalina Hristova,Elena B Pasquale,Christopher King,Pranjali Kanvinde

doi:10.1038/s42003-018-0017-7

Abstract

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.

Highlights

The Eph receptors are the largest family of receptor tyrosine kinases and play critically important roles in tissue organization and homeostasis as well as in many pathological processes[1,2,3]
Kinase-dependent signaling by the EphA2 receptor is strongly activated in cells stimulated with ephrinA1-Fc22
Ephrin Fc fusion proteins are dimeric and for some Eph receptors they have been shown to cause receptor clustering and high activation only when they are oligomerized with anti-Fc antibodies, mimicking the clustering induced by the endogenous plasma membrane-anchored ephrin ligands[2, 24,25,26,27]

Summary

Introduction

The Eph receptors are the largest family of receptor tyrosine kinases and play critically important roles in tissue organization and homeostasis as well as in many pathological processes[1,2,3]. Given the high diversity of functional outcomes mediated by EphA2 kinase-dependent signaling, we asked whether this receptor may be capable of forming different types of oligomers (dimers or clusters) in the plasma membrane, depending on the nature of the activating ligand. To explore this possibility, we assessed the homo-association of EphA2 receptor molecules in the plasma membrane in the presence of three types of ligands (dimeric ephrinA1-Fc, monomeric ephrinA1, and an engineered peptide ligand) in comparison with EphA2 in the absence of ligand. The distinctive effects we observed for mutations in the dimerization or the clustering interface show that EphA2 is capable of forming several oligomers that are stabilized through distinct interfaces

Methods

Results

Conclusion