Integrin-Associated Protein (IAP, Also Termed CD47) Is Involved in Stroma-Supported Erythropoiesis

Abstract

Erythropoiesis is regulated by the hematopoietic microenvironment of the spleen, fetal liver, and bone marrow in mice. We previously showed that established stromal cells from these organs selectively support erythropoiesis in vitro. To identify the cell surface molecule(s) on the stromal cells involved in erythropoiesis, we raised monoclonal antibodies (MAbs) to MSS62 stromal cells derived from newborn spleen and obtained MAb100.1, which partially inhibited the stroma-supported erythropoiesis in vitro. Using an expression cDNA library of MSS62 cells, we cloned a gene encoding the protein recognized by MAb100.1 and identified it as integrin-associated protein (IAP, also termed CD47), which may play a general role in integrin-mediated signal transduction. IAP/CD47 is expressed in the stromal cells of spleen, fetal liver, and bone marrow, and in a variety of hematopoietic cells including erythroblasts. Thus, IAP may be partly involved in the erythropoietic supporting ability of the stromal cells.

Phylogenetic Divergence of CD47 Interactions with Human Signal Regulatory Protein α Reveals Locus of Species Specificity

“…Expression Vectors and CD47 Mutagenesis-Human CD47 (hCD47; isoform 2) (26), mouse CD47 (mCD47; isoform 2) (26), mCD47 lacking the 21-amino acid insert (4,27), and other CD47 variants were typically PCR-amplified, digested with XhoI and BamHI (New England Biolabs, Beverly, MA), and ligated to similarly digested vector, pEGFP-N3 (Clontech), which results in an in-frame fusion of EGFP at the C terminus of full-length CD47. Single site mutants were prepared using the QuikChange mutagenesis protocol (Stratagene, La Jolla, CA), and multiple site mutants were prepared using sequential application of the QuikChange protocol or through gene synthesis by PCR.…”

A global role for EKLF in definitive and primitive erythropoiesis

“…In addition to these validated genes, other blood group antigens and related proteins are likely EKLF target genes (Table 3). These include glycophorin A (GPA), CD47 (an Rh antigen-associated protein 66 ), and CD59 (a GPI-anchored protein lost in paroxysmal nocturnal hemoglobinuria [PNH]). Interestingly, most of these proteins coexist in a mega-complex that links the membrane to the underlying cytoskeleton.…”

The Role of CD47 in Neutrophil Transmigration

“…Marker activities are plotted as a percentage of total recovered from all gradient fractions. As can be seen, the majority of plasma membrane is in fractions 11-17, secondary granules are in fractions [17][18][19][20][21][22][23][24], and primary granules are in fractions 20 -24. The lower panels represent immunoblots of CD11b CD18 and CD47 from subcellular organelle-containing sucrose fractions (30-l protein samples) in the panels above using polyclonal rabbit anti-CD11b (R7928A) and anti-CD47 mAb PF3.…”

“…CD47 has been shown to bind to the C terminus of thrombospondin-1 (18), therefore suggesting a role in platelet activation. Anti-CD47 antibodies have also been used to implicate CD47 in T cell activation (19,20), T and B cell apoptosis (21,22), and stroma-supported erythropoiesis (23). Recently, CD47 has been shown to bind to P84 (also termed SIRP␣, Bit, SHPS-1, and MFR) (24 -26), and this interaction has been broadly implicated in the regulation of memory formation, macrophage multinucleation, B cell aggregation, and red blood cell self-recognition in mice (27,28).…”