Molecular characterization of the commonly used human androgen receptor expression vector, pSG5-AR.

Abstract

pSG5-AR is a commonly used androgen receptor (AR) expression vector. However, a detailed molecular characterization of this construct has not been published. In this study, we describe the molecular organization of the above plasmid and analyze the AR transcript coded by the above construct. pSG5-AR was sequenced by the standard dideoxy sequencing method. The obtained sequence was analyzed by the DS Gene software. A molecular map of the pSG5-AR plasmid as well as a map of the AR insert is provided. The AR transcript from pSG5-AR is lacking significant portions of the 5'- and 3'-untranslated region (UTR) and contains shorter than average CAG and GGC repeats. The above characteristics of the pSG5-AR are significant and may result in different regulation pattern of expression of the expressed AR in comparison to the endogenous gene. Such a conclusion is based on the knowledge that post-transcriptional regulation plays an important role in controlling the levels of AR in a cell. Such regulation is controlled by the regulatory elements within the 5'- and 3'-UTRs of the AR transcript. In addition, this vector might be coding for an AR with a different transactivational capacity than the endogenous AR gene. The transactivational activity of AR was shown to be affected by the size of the trinucleotide-repeat-regions (CAG and GGC) within the gene.