In:
Biochemical Journal, Portland Press Ltd., Vol. 378, No. 3 ( 2004-03-15), p. 999-1006
Abstract:
Previous studies have shown that human DHFR (dihydrofolate reductase), in addition to its critical role in DNA biosynthesis, functions as an RNA-binding protein. The interaction between DHFR and its own mRNA results in translational repression. In this study, we characterized the cis-acting elements on human DHFR mRNA that are required for the DHFR mRNA–DHFR protein interaction. Using a series of gel-shift and nitrocellulose filter-binding assays, a 164 nt RNA sequence, corresponding to nt 401–564, was identified within the coding region that binds to DHFR protein with an affinity similar to that of full-length DHFR mRNA. To document in vivo biological activity, various DHFR sequences contained within the coding region were cloned on to the 5´ end of a luciferase reporter plasmid, and transient transfection experiments were performed using human colon cancer RKO cells. In cells transfected with p644/DHFR:401–564, luciferase activity was decreased by 50% when compared with cells transfected with the p644 plasmid alone. Luciferase mRNA levels were identical under each of these conditions, as determined by Northern-blot analysis. In cells transfected with p644/DHFR:401–564, luciferase activity was restored to almost 100% of control when cells were treated with the antifolate analogue methotrexate or with a short-interfering RNA targeting DHFR mRNA. These findings provide evidence that the DHFR 401–564 sequence is a DHFR-response element. In vitro and in vivo studies further localized this cis-element to an 82 nt sequence corresponding to nt 401–482. This work provides new insights into critical elements that mediate RNA–protein interactions.
Type of Medium:
Online Resource
ISSN:
0264-6021
,
1470-8728
Language:
English
Publisher:
Portland Press Ltd.
Publication Date:
2004
detail.hit.zdb_id:
1473095-9
SSG:
12
