Ephrin/Eph receptor interaction facilitates macrophage recognition of differentiating human erythroblasts

Lea Hampton-O'Neil, Charlotte Severn, Sonam Gurung, Stephen Cross, Catherine Nobes, Ash Toye

Research output: Contribution to journalArticle (Academic Journal)

Abstract

Erythropoiesis is one of the most efficient cellular processes in the human body producing
approximately 2.5 million red blood cells every second. This process occurs in a bone marrow niche comprised of a central resident macrophage surrounded by differentiating erythroblasts, termed an erythroblastic island. It is not known what initially attracts the macrophage to erythroblasts to form these islands. The ephrin/EPH receptor family are known to regulate heterophilic cell-cell adhesion.
We find that human VCAM1+ and VCAM1- bone marrow macrophages and in vitro cultured
macrophages are ephrin-B2 positive, whereas differentiating human erythroblasts express EPHB4, EPHB6 and EPHA4. Furthermore, we detect a rise in integrin activation on erythroblasts at the stage at which the cells bind which is independent of EPH receptor presence. Using a live cell imaging assay, we show that specific inhibitory peptides or shRNA depletion of EPHB4 cause a significant reduction in the ability of macrophages to interact with erythroblasts but does not affect integrin
activation. This study demonstrates for the first time that EPHB4 expression is required on
erythroblasts to facilitate the initial recognition and subsequent interaction with macrophages,
alongside the presence of active integrins.
Original languageEnglish
Number of pages36
JournalHaematologica
Volume104
Issue number8
Early online date13 Jun 2019
DOIs
Publication statusE-pub ahead of print - 13 Jun 2019

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