SEQUENCE AND EXPRESSION ANALYSIS OF BOVINE PIGMENT EPITHELIUM-DERIVEDFACTOR

PEDF, a member of the serpin superfamily of proteins related through t heir highly conserved folded conformation, has neurotrophic properties , including promotion of neurite-outgrowth and neuronal survival. Prev iously, we have purified and characterized PEDF protein from extracell ular matrixes of bovine eyes. Here, we show the cDNA sequence and expr ession analysis of bovine PEDF. Northern analysis of RNA from bovine r etinal pigment epithelium (RPE) and neural retina using a human PEDF c DNA fragment reveals expression of the PEDF gene only for RPE. Sequenc e analysis of a cDNA clone isolated from bovine RPE predicts a polypep tide of 416 amino acid residues that shares 88.6% and 85% amino acid i dentity with human and mouse PEDF, respectively, It has an N-terminal signal peptide, a consensus glycosylation site and homology with serpi ns including the conserved residues required for maintaining the serpi n tertiary structure. Cell-free expression of the bovine PEDF cDNA by in vitro transcription and translation yields a precursor polypeptide of 45,000-Mr that immunoprecipitates with an antibody to human PEDF. E xpression analysis in stably transfected baby hamster kidney cells sho ws that the recombinant bovine protein is secreted to the culture medi a as a mature 50,000-Mr protein, which induces neurite-outgrowth on re tinoblastoma cells, like the naturally-occurring PEDF protein. Thus, t he bovine PEDF cDNA isolated here codes for a functional soluble secre ted PEDF glycoprotein. (C) 1998 Elsevier Science B,V. All rights reser ved.