Inhibition of platelet-derived growth factor autocrine growth stimulation by a monoclonal antibody to the human alpha platelet-derived growth factor receptor.

A potent neutralizing monoclonal antibody to the human alpha platelet-derived growth factor (PDGF) receptor (alpha PDGFR) was raised by immunizing BALB/c mice with 32D cells expressing the human alpha PDGFR. This monoclonal antibody, designated alpha R1, immunoprecipitated human, monkey, rabbit, pig, dog, and cat, but not hamster, rat, or mouse alpha PDGFRs. Comparison with PR292, a monoclonal antibody previously generated against the alpha PDGFR, showed that both recognized alpha PDGFR extracellular domains, but neither demonstrated reactivity against the beta PDGFR.

Five PDGF B amino acid substitutions convert PDGF A to a PDGF B-like transforming molecule.

We used site-directed mutagenesis to determine the minimum number of PDGF B residues needed to convert PDGF A to a potently transforming PDGF B-like molecule. Substitution of two PDGF B subdomains, 106-115 and 135-144, were found to be critical. These substitutions were sufficient to broaden the ability of PDGF A to activate beta as well as alpha platelet-derived growth factor (PDGF) receptors and increase its transforming efficiency to that of PDGF B.

A novel mechanism regulating growth factor association with the cell surface: identification of a PDGF retention domain.

Platelet-derived growth factor (PDGF) chimeras were used to map a domain responsible for either efficient secretion of PDGF-A or the tight cell association of PDGF-B to their carboxy-terminal domains. Introduction of stop codons within PDGF-A or PDGF-B further dissected their respective carboxy-terminal domains. Although successive deletions of the PDGF-A carboxyl terminus did not impair its secretion, incremental deletions from the carboxyl terminus of PDGF-B abrogated its membrane retention properties and promoted secretion.

A small v-sis/platelet-derived growth factor (PDGF) B-protein domain in which subtle conformational changes abrogate PDGF receptor interaction and transforming activity.

Deletion scanning mutagenesis within the transforming region of the v-sis oncogene was used to dissect structure-function relationships. Mutations affecting codons within a domain encoding amino acids 136 through 148 had no effect upon homodimer formation or recognition by antisera which detect determinants dependent upon native intrachain disulfide linkages, yet the same mutations completely abolished transforming activity. A platelet-derived growth factor B (PDGF B) monoclonal antibody that prevents its interaction with PDGF receptors recognized v-sis, delta 142 (deletion of codon 142), and delta 148 but not delta 136, delta 137, or delta 139 mutants.

Molecular localization of the transforming and secretory properties of PDGF A and PDGF B.

Human platelet-derived growth factor (PDGF) is a connective tissue cell mitogen comprised of two related chains encoded by distinct genes. The B chain is the homolog of the v-sis oncogene product. Properties that distinguish these ligands include greater transforming potency of the B chain and more efficient secretion of the A chain.