Activation of sickle red blood cell adhesion via integrin-associated protein/CD47–induced signal transduction
Julia E. Brittain, … , Eugene P. Orringer, Leslie V. Parise
Julia E. Brittain, … , Eugene P. Orringer, Leslie V. Parise
Published June 15, 2001
Citation Information: J Clin Invest. 2001;107(12):1555-1562. https://doi.org/10.1172/JCI10817.
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Article

Activation of sickle red blood cell adhesion via integrin-associated protein/CD47–induced signal transduction

Abstract

Peripheral human red blood cells (RBCs) are not generally known to become activated and adhesive in response to cell signaling. We show, however, that soluble thrombospondin via integrin-associated protein (IAP; CD47) increases the adhesiveness of sickle RBCs (SS RBCs) by activating signal transduction in the SS RBC. This stimulated adhesion requires occupancy of IAP and shear stress and is mediated by the activation of large G proteins and tyrosine kinases. Reticulocyte-enriched RBCs derived from sickle-cell disease (SCD) patients are most responsive to IAP-induced activation. These studies therefore establish peripheral SS RBCs as signaling cells that respond to a novel synergy between IAP-induced signal transduction and shear stress, suggesting new therapeutic targets in SCD.

Authors

Julia E. Brittain, Kathryn J. Mlinar, Christopher S. Anderson, Eugene P. Orringer, Leslie V. Parise

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Shear stress and IAP stimulation induce tyrosine phosphorylation and dep...
Shear stress and IAP stimulation induce tyrosine phosphorylation and dephosphorylation in SS RBCs. (a) SS RBCs (1 × 107) were lysed after 2 minutes of shear stress alone (1 dyne/cm2), and tyrosine phosphorylated proteins were immunoprecipitated with PY20 (lanes 2 and 5), PY99 (lanes 1 and 4), or control IgG (lane 3) and Western blotted with 4G10. Exposure to shear induces the phosphorylation of several bands at ∼100 kDa and 70 kDa (arrows). Notable dephosphorylation occurs at approximately 45, 30, and 27 kDa (representative of three patients). (b) 4N1K (100 μM) plus shear induces the further phosphorylation at 100 kDa and 70 kDa relative to 4NGG plus shear (lane 5). Control IgG fails to detect this phosphorylation (lane 4). NeitherWBCs (200,000, lane 1) nor platelets (50,000, lane 2) exhibit any change in phosphorylation (blot representative of four patients). (c) Pretreatment with piceatannol (lane 2) blocks tyrosine phosphorylation of the 100- and 70-kDa bands induced by shear plus 4N1K treatment (lane 1, top arrows) back to control peptide levels (lane 3) (blot representative of two patients). Piceatannol potentiated the 4N1K-induced phosphorylation of a 33-kDa band (lane 2, lower arrow). (d) Normal (AA) RBCs do not exhibit any change in tyrosine phosphorylation in response to 4N1K and shear stimulation (blot representative of four donors and exposed eight times longer than SS blots) using either PY99 (lanes 1 and 4), PY20 (lanes 2 and 5), or control IgG (lane 3). Note the lack of phosphorylated bands at 100 kDa and 70 kDa (arrows).