Post-transcriptional control of cyclooxygenase-2
Cyclooxygenase-2 is an early response gene that is rapidly and transiently induced by a variety of extracellular ligands in many cell types, including macrophages and mesangial cells. The 3' untranslated region (UTR) of cox-2 mRNA plays a vital role in its post-transcriptional control by regulating mRNA stability and translation. The proximal 60-nucleotides of the 3' UTR contain highly conserved Adenosine-uridine Rich Elements (AREs)---AUUUA, which are known to regulate mRNA stability and translation.;Insertion of the 1--60 sequence was sufficient to cause a marked decrease (>65%) in expression of a luciferase reporter-gene, in both rat mesangial and RAW 264.7 cells. Although reporter-gene constructs proved unresponsive to stimulation with IL1beta in the rat mesangial cells, a response was seen with LPS in the RAW 264.7 cells, which was dependent on the proximal 20 nucleotides of the 1--60 sequence.;Electromobility shift assays revealed that multiple RNA binding proteins, including HuR, TIA-1, TIAR, hnRNP U and AUF1, interacted with this region of the cyclooxygenaase-2 3' TR, with some noticeable differences occurring following removal of the LPS responsive sequence.;These studies provide further evidence of the role played by the 3 ' UTR in the post-transcriptional control of cyclooxygenase-2, as well as identifying several RNA binding proteins likely to be involved in this process.