Promoter structure and gene expression of the mouse inositol 1,4,5-trisphosphate receptor type 3 gene

Inositol 1,4,5-trisphosphate receptor type 3 (IP(3)R3) is a ubiquitously ex pressed IP3R gene in the IP3R gene family. We identified an upstream region of the mouse IP(3)R3 genomic DNA. Transcription start points for the IP(3) R3 gene were found to be located mainly at four sites between nucleotide po sition -325 and -285 relative to the first ATG codon. The major start point was mapped around -325. Transcription promotion ability was detected betwe en -325 and -285 in an IP(3)R3 proximal promoter sequence. The promoter had no TATA-box but was highly GC-rich and contained two putative Sp1-binding sites. There was no sequence similarity between promoter regions of IP(3)R3 and IP(3)R2, another ubiquitous gene, except for GC-boxes. By using a seri es of 5'-truncation versions and a transient luciferase assay, we detected multiple common and cell-type-dependent regulatory regions within the dista l promoter sequence downstream from -4.0 kb that function positively or neg atively. The IP(3)R3 gene was highly transcribed in the kidney, spleen, hea rt, and skeletal muscle, and this tissue distribution pattern was nearly co mplementary to that Of IP(3)R2. We found that IP(3)R3 gene expression was r epressed in retinoic acid-treated and neural differentiated P19 mouse embry onic carcinoma cells. (C) 2001 Elsevier Science B.V. All rights reserved.