Identification of critical amino-acid residues on the erythroid intercellular adhesion molecule-4 (ICAM-4) mediating adhesion to αV integrins

Abstract

Intercellular adhesion molecule-4 (ICAM-4, syn. LW glycoprotein) interacts with the integrins alpha(L)beta(2), alpha(M)beta(2), A(4)beta(1), the alpha(V) family, and alpha(IIb)beta(3). Systematic mutagenesis of surface-exposed residues conserved between human and murine ICAM-4 defined 12 single amino-acid changes that affect the interaction of ICAM-4 with alpha(V) integrins. Mutation of 10 of these residues, 8 of which are spatially close on the surface of the molecule, led to a reduction in adhesion. Moreover, peptides corresponding to regions of ICAM-4 involved in its interaction with alpha(V) integrins inhibited these interactions. The other 2 mutations increased the extent of interaction of ICAM-4 with alpha(V) integrins. These mutations appear to prevent glycosylation of N160, suggesting that changes in glycosylation may modulate ICAM-4-alpha(V) integrin interactions. The region of ICAM-4 identified as the binding site for alpha(V) integrins is adjacent to the binding sites for alpha(L)beta(2) and alpha(M)beta(2). Selective binding of ICAM-4 to different integrins may be important for a variety of normal red cell functions and also relevant to the pathology of thrombotic disorders and vasoocclusive events in sickle cell disease. Our findings suggest the feasibility of developing selective inhibitors of ICAM-4-integrin adhesion of therapeutic value in these diseases.

Modulation of erythroid adhesion receptor expression by hydroxyurea in children with sickle cell disease

“…[7][8][9] More recently, two other molecules not restricted to reticulocytes have been implicated, namely Lutheran blood group/basal cell adhesion molecule (Lu/BCAM), a receptor for the extracellular matrix protein laminin α5 10,11 and intercellular adhesion molecule-4 (ICAM-4), otherwhise known as LW blood group glycoprotein, which binds different types of integrins, particularly αVβ3. [12][13][14] Other molecules may also increase the adhesiveness of sickle red cells. 6 On the endothelial side, the major cell membrane ligands for red blood cell adhesion molecules include vascular cell adhesion molecule-1 (VCAM-1), CD36, αVβ3 integrin and selectins, 4,5 but recently a new interaction that involves endothelial Lu/BCAM and α4β1 integrin on sickle red cells has been described.…”

Extrinsic and intrinsic control by EKLF (KLF1) within a specialized erythroid niche

“…Extensive macrophage-erythroblast and erythroblast-erythroblast adhesive interactions are necessary for a thriving definitive erythropoietic community. As a result, structural proteins that mediate these interactions (Fabriek et al, 2007;Lee et al, 2006;Liu et al, 2007;Mankelow et al, 2004;Sadahira et al, 1995;Soni et al, 2006) as well as transcriptional factors (Gutiérrez et al, 2004;Iavarone et al, 2004;Kusakabe et al, 2011) are both crucial for promoting an effective differentiative environment. Erythroblasts can proliferate, mature and enucleate in vitro in the absence of other cell types; however, this process is typically very inefficient at all stages (Hanspal et al, 1998;Rhodes et al, 2008).…”

The Laminin 511/521 Binding Site on the Lutheran Blood Group Glycoprotein is Located at theFlexible Junction of Ig Domains 2 and 3

“…Point mutations were inserted into human Lu gp cDNA clones 42 encoding the five extracellular domains in pIg vector by PCR amplification as described 43 . Mutant clones were confirmed by DNA sequence analysis.…”

“…Mutant clones were confirmed by DNA sequence analysis. Native and mutant Lu gpFc and Muc-18 Fc (a gift from Dr Simmons (Glaxo SmithKline, Harlow, UK) were expressed in COS-7 cells, purified using protein A-Sepharose and quantified as described 43 .…”