An 11 nt element in the 3’Untranslated Region of the ß–PDE gene is involved in the control of gene expression

Abstract

Abstract: : Purpose: Previously, we reported that in Y–79 cells and in Xenopus laevis tadpole heads, two 100 nt fragments from the 3’untranslated region (3’UTR) of rod cGMP–phosphodiesterase ß–subunit (ß–PDE) enhance luciferase reporter gene expression above that produced by the complete 3'UTRs of ß–PDE, SV–40, and other photoreceptor specific genes. The purpose of our current work was to identify short sequence elements present in these 100 nt fragments that are responsible for the observed increases in expression. Methods: Highly conserved regions of the ß–PDE 3'UTR were cloned downstream of the luciferase gene, and upstream of the poly–A signal, in a modified pGL3 vector under control of the SV–40 promoter. These constructs were transfected into Y–79 retinoblastoma cells. Luciferase assays were performed on harvested cell lysates. Results: A short sequence (11 nt) was found to be conserved across different species including mouse, dog, cow, and human. This 11 nt sequence increased luciferase reporter gene expression to a level comparable to that observed with the entire 100 nt fragment in which it is present. This 11 nt sequence is predicted to form secondary structures that could bind protein factors. Conclusions: These 11 nt constitute a novel 3'UTR element involved in regulation of ß–PDE expression. We propose that this element plays an important role in the expression the ß–PDE gene and other genes in which it may reside.

Keywords: gene/expression • photoreceptors • transcription