Abstracts Biological Sciences

Transcription regulation of murine parathyroid hormoneparathyroid hormone related peptide receptor (PTH1R)

by Mei Yee Kwan

Our first aim was to generate transgenic mice to express beta-galactosidase reporter gene under the control of the two promoters. The model would allow us to study the temporal and spatial expression of PTH1R during the onset of embryonic endochondral ossification, and in the adult. Our transgenic animals would allow us to identify regulatory elements that are essential for tissue specific PTH1R expression. We have cloned 11 kilobases of mouse PTH1R gene promoter sequence containing four untranslated exons U1, U2, U3 and SS, and fused this to a Lac Z reporter gene, which was in turn fused to a 250 by fragment containing the A-rich polyadenylylation signal. Three additional constructs were made with deletion of transcription start sites in exon U1 (DeltaU1), U3 (DeltaU3) and both (DeltaU1DeltaU3). Both the control and transgenic adult littermates showed high levels of beta-galactosidase-like activity in epiphyseal growth plate and kidney medulla. However, beta-galactosidase activity was not observed for fetuses aged post coital 14.5 and 15.5 days. We were unable to show tissue specific reporter activity in our transgenic animals. In other study, we found that P2 is the predominant promoter controlling PTH1R gene expression in both bone and cartilage. (Abstract shortened by UMI.)