ISOLATION AND CHARACTERIZATION OF THE HUMAN PROSAPOSIN PROMOTER

Prosaposin is a multifunctional protein that encodes four glycoprotein s, named saposins A, B, C and D. They participate in the catabolism of glycosphingolipids in lysosomes. When secreted, intact prosaposin may function as a neuritogenic factor. Human and mouse prosaposin display ed similar temporal and spatial regulation of expression. To gain insi ght into the transcriptional regulation of this locus, the 5' region w as characterized from the human prosaposin gene. The putative human pr omoter was shown to be TATA-less, i.e. it belonged to the TATA-less ho usekeeping gene family. The transcription initiation sites were locali zed to -23, -27, -31 and -83 bp 5' to ATG, compared to -87: and -94 bp in the mouse. In SK-N-SH neuroblastoma cells? positive regulatory ele ments were detected -343 to -813 bp upstream of ATG. A negative regula tory region existed between -813 and -2500 bp using SK-N-SH, H441 and NS20Y cells. EMSA and nNA-footprint analysis showed that Spl and Sp3 a re involved in human prosaposin gene regulation. Compared to the mouse promoter, the human promoter is missing a Spl cluster within a 310-bp upstream segment, and has AP-1, Oct-1 and two ROR alpha sites that ar e protected from DNaseI by selected nuclear extracts. (C) 1998 Elsevie r Science B.V. All rights reserved.