Cholesterol-Dependent Dimerization and Conformational Dynamics of EphA2 Receptors: Insights from Coarse-Grained and All-Atom Simulations

The EphA2 transmembrane receptor is a key regulator of cellular growth, differentiation, and motility, and its overexpression in various cancers positions it as a promising biomarker for clinical cancer management. EphA2 signaling is mediated through ligand-induced dimerization, which stabilizes its dimeric state via conformational changes in the extracellular region and is linked to the intracellular kinase region via the transmembrane (TM) domain. Similar to many receptor tyrosine kinases, the juxtamembrane (JM) region, located between the TM and catalytic domains, coordinates with the TM domain to facilitate signal transduction. Electrostatic interactions between basic residues of the JM region and signaling lipids, such as PIP2 and PIP3, play a critical role by sequestration thereby inhibiting phosphorylation of the JM and other intracellular tyrosines. Cholesterol’s potential role in allosterically modulating EphA2 activation has remained unclear. Therefore, elucidating the structural mechanism of EphA2 dimerization and its membrane interactions is essential for understanding the influence of these lipids. In this study, we modeled the TM-full JM peptide of the EphA2 receptor and employed both coarse-grain (CG) and all-atom (AA) simulations to investigate the conformational transitions of the EphA2 transmembrane region dimer in cholesterol-rich and cholesterol-deficient membranes. Our study reveals that cholesterol stabilizes specific EphA2 TM dimers and TM-JM PIP2 interactions, highlighting the critical role of membrane composition in regulating EphA2 dimerization, oligomerization, and clustering.