title: Binding of pigment epithelium-derived factor (PEDF) to retinoblastoma cells and cerebellar granule neurons. Evidence for a PEDF receptor.
abstract: Pigment epithelium-derived factor (PEDF) has neuronal differentiation and survival activity on retinoblastoma and cerebellar granule (CG) cells. Here, we investigated the presence of PEDF receptors on retinoblastoma Y-79 and CG cells. PEDF radiolabeled with (l25)I remained biologically active and was used for radioligand binding analysis. The binding was saturable and specific to a single class of receptors on both cells and with similar affinities (K(d) = 1.7-3.6 nM, B(max) = 0.5-2.7 x 10(5) sites/Y-79 cell; and K(d) = 3.2 nM, B(max) = 1.1 x 10(3) sites/CG cell). A polyclonal antiserum to PEDF, previously shown to block the PEDF neurotrophic activity, prevented the (125)I-PEDF binding. We designed two peptides from a region previously shown to confer the neurotrophic property to human PEDF, synthetic peptides 34-mer (positions 44-77) and 44-mer (positions 78-121). Only peptide 44-mer competed for the binding to Y-79 cell receptors (EC(50) = 5 nM) and exhibited neuronal differentiating activity. PEDF affinity column chromatography of membrane proteins from both cell types revealed a PEDF-binding protein of approximately 80 kDa. These results are the first demonstration of a PEDF-binding protein with characteristics of a PEDF receptor and suggest that the region comprising amino acid positions 78-121 of PEDF might be involved in ligand-receptor interactions.
authors.affiliation: Laboratory of Retinal Cell Biology, NEI, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: E
authors.initials: E
authors.lastname: Alberdi
authors.forename: M S
authors.initials: MS
authors.lastname: Aymerich
authors.forename: S P
authors.initials: SP
authors.lastname: Becerra
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D002454:Cell Differentiation; D002531:Cerebellum / Q000166:cytology*; D002846:Chromatography, Affinity; D003594:Cytoplasmic Granules; D005136:Eye Proteins / Q000378:metabolism; D006801:Humans; D009414:Nerve Growth Factors / Q000378:metabolism*; D016501:Neurites; D009474:Neurons / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D018013:Receptors, Neuropeptide / Q000302:isolation & purification / Q000378:metabolism*; D012175:Retinoblastoma / Q000378:metabolism*; D015843:Serpins / Q000378:metabolism*; D014018:Tissue Distribution; D000099174:Pigment Epithelium-Derived Factor
chemical_list: D005136:Eye Proteins; D009414:Nerve Growth Factors; D010446:Peptide Fragments; D011506:Proteins; D018013:Receptors, Neuropeptide; D015843:Serpins; D000099174:Pigment Epithelium-Derived Factor; C400531:pigment epithelium-derived factor receptor