Regulation of EPC-1/PEDF in normal human fibroblasts is posttranscriptional

• Published in: Journal of cellular biochemistry Vol. 79; no. 3; pp. 442 - 452
• Main Authors: Coljee, Vincent W., Rotenberg, Mitch O., Tresini, Maria, Francis, Mary Kay, Cristofalo, Vincent J., Sell, Christian
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 07.09.2000
• Subjects: Animals; Blotting, Northern; Cattle; Cell Division; Cell Line; Cellular Senescence; Culture Media - pharmacology; Culture Media, Serum-Free; EPC-1; Eye Proteins; Fetal Blood - physiology; Fibroblasts - drug effects; Fibroblasts - metabolism; Genes, fos; human fibroblasts; Humans; Nerve Growth Factors; PEDF; Promoter Regions, Genetic; Protein Biosynthesis; Proteins - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA Processing, Post-Transcriptional - drug effects; RNA, Heterogeneous Nuclear - metabolism; RNA, Messenger - metabolism; Serpins - biosynthesis; Serpins - genetics
• ISSN: 0730-2312; 1097-4644
• DOI: 10.1002/1097-4644(20001201)79:3<442::AID-JCB90>3.0.CO;2-Z

The EPC‐1 (early population doubling level cDNA‐1) gene, also known as pigment epithelium‐derived factor, encodes a protein belonging to the serine protease inhibitor (serpin) superfamily that has been reported to inhibit angiogenesis and proliferation of several cell types. We have previously reported that the EPC‐1 mRNA and the secreted EPC‐1 protein are expressed at levels more than 100‐fold higher in early passage, G0, WI‐38 cells compared to either proliferating or senescent WI‐38 fibroblasts. To examine the molecular mechanisms that regulate changes in EPC‐1 gene expression in WI‐38 cells, we isolated and characterized the human EPC‐1 gene and determined the mRNA cap site. Transcriptional assays showed no change in the transcription rates of EPC‐1 between young proliferating, quiescent, and senescent WI‐38 cells. These results suggest posttranscriptional regulation of the EPC‐1 gene. Reverse transcriptase polymerase chain reaction measurements (of hnRNA) indicate regulation at the hnRNA level. The regulation of the EPC‐1 gene at the level of hnRNA can explain the observed slow increase in the steady‐state EPC‐1 mRNA levels when cells become quiescent. The reduction of EPC‐1 mRNA levels that occurs when cells exit G0 and are induced to proliferate can be accounted for by a reduction of the EPC‐1 mRNA stability in stimulated cells as compared to quiescent cells. J. Cell. Biochem. 79:442–452, 2000. © 2000 Wiley‐Liss, Inc.