A Single Element in the 3{'} UTR of the Apical Sodium-Dependent Bile Acid Transporter Controls both Stabilization and Destabilization of mRNA

mRNA stability appears to play a key role in the ontogenic regulation of the apical sodium dependent bile acid transporter (ASBT). The RNA binding proteins, Hu antigen R (HuR) and Tristetraprolin (TTP), stabilize and destabilize ASBT mRNA, respectively. Potential HuR binding sites were assessed by sequence analysis in the context of prior in vitro functional analyses of the rat ASBT 3’UTR. Wild type and mutant binding sites were investigated by gel shift analysis using IEC-6 cell extracts. The functional consequences of binding site mutations were assessed using two different hybrid reporter constructs linking the 3’UTR element to a either a luciferase or a ß-globin coding mRNA sequence. A specific metastasis associated gene 1 cis-element (MTA1) was identified in the ASBT 3’UTR that became associated with proteins in IEC-6 cell extracts and could be supershifted by HuR or TTP antibodies. Mutation of this cis-element abrogated the gel shift of IEC-6 proteins. Furthermore hybrid constructs containing a mutant MTA1 element had reduced responses to modulation of HuR or TTP. For the first time we have identified a single specific sequence element in the 3’UTR of the rat ASBT mRNA that mediates counter-regulatory changes in mRNA abundance in response to both HuR and TTP.

Source: BJ Cell - June 20, 2014 Category: Biochemistry Authors: D M Soler, A Ghosh, F Chen, B L Shneider Tags: BJ Gene Source Type: research