Coexpression of the genes for platelet-derived growth factor B-chain receptor and macrophage colony-stimulating factor 1 receptor during monocytic differentiation.

Receptors for platelet-derived growth factor (PDGF) have not been identified previously to our knowledge in human myeloid cells that also produce PDGF. Here we report that phorbol ester-treated myeloid cells differentiated along the monocytic lineage express both a full-length 5.5-kilobase (kb) mRNA and a predominant, truncated 4.6-kb mRNA coding for the PDGF B-chain receptor (PDGF-BR). PDGF-BR was identified in phorbol ester-differentiated myeloid cells by indirect immunofluorescence with an antibody specific to PDGF-BR. This anti-PDGF-BR was also used in immunoprecipitation studies to demonstrate that lysates of phorbol ester-differentiated myeloid cells contain PDGF-BR molecules of 37 kDa to 130 kDa. The results also show that the tandemly linked genes for PDGF-BR and the macrophage colony-stimulating factor 1 receptor are coexpressed in the phorbol ester-differentiated myeloid cells. Expression of these two receptor genes has not been shown previously in any cell type to our knowledge.