Cloning and characterization of the murine Pkd2 promoter

Pkd2, the mouse homologue of PKD2, the gene responsible for the second form of autosomal dominant polycystic kidney disease, is highly expressed in fe tal and adult mouse tissues. The expression of Pkd2 is developmentally regu lated. To begin to dissect out the regulatory mechanism of Pkd2 expression, we characterized the basic features of the gene structure and identified p otential cis-regulatory elements of Phd:! transcription. Pkd2 spans 42 kb w ith a transcription start site 165 bp upstream of the translation start cod on. Exon 1 of Pkd2 is 755 bp long, and the full-length transcript is 5215 b p, The Pkd2 promoter region is GC-rich and lacks a consensus TATA or CCAAT box. Consensus binding sites for the transcription factors Sp-1, NF-1, and Ap-2 lie in the 5' upstream region of Pkd2. The Sp-l binding site is conser ved in 5' upstream sequences of both the mouse and the human genes. The CAT activity of a series of upstream segments from +178 to -2749 was assessed in MDCK, LLCPK1, COS-7, and HEk293 cells. Deletion analysis identified a 40 9-bp fragment from position -221 to +178 responsible for basal promoter act ivity. A 922-bp fragment from -744 to +178 showed the highest level of CAT activity in the cell lines tested. These data define a functional promoter candidate region for Phd2. (C) 2000 Academic Press.