Post-transcriptional regulation of glucose transporter-1 by an AU-rich element in the 3′ UTR and by hnRNP A2

ME Griffin, BJN Hamilton, KM Roy, M Du… - Biochemical and …, 2004 - Elsevier
ME Griffin, BJN Hamilton, KM Roy, M Du, AM Willson, BJ Keenan, XW Wang, RC Nichols
Biochemical and biophysical research communications, 2004Elsevier
Glucose transporter-1 (GLUT1) mediates uptake of glucose and is up-regulated in some
cancers. The amount of this membrane protein is regulated by a post-transcriptional
mechanism in which mRNA binding proteins recognize cis-acting elements in the 3′-
untranslated (3′ UTR) of the mRNA. To identify cis elements in GLUT1 mRNA we
introduced 3′ UTR sequences into the 3′ UTR of the luciferase gene in a reporter
construct. A 30nt adenosine–uridine-rich element (“GLUT1 AURE”) inhibited luciferase …
Glucose transporter-1 (GLUT1) mediates uptake of glucose and is up-regulated in some cancers. The amount of this membrane protein is regulated by a post-transcriptional mechanism in which mRNA binding proteins recognize cis-acting elements in the 3-untranslated (3UTR) of the mRNA. To identify cis elements in GLUT1 mRNA we introduced 3UTR sequences into the 3UTR of the luciferase gene in a reporter construct. A 30nt adenosine–uridine-rich element (“GLUT1 AURE”) inhibited luciferase activity in HEK-293 cells. This inhibitory effect was confirmed by deleting the GLUT1 AURE from a reporter containing the full-length 3UTR. Deletion of the GLUT1 AURE caused reporter activity to increase. Deletion of a larger fragment (“Bsu” region) containing the GLUT1 AURE increased reporter activity still further, suggesting that there are additional cis elements in the GLUT1 mRNA. The GLUT1 AURE was also active in GBM-T98G glioblastoma cells. Next, we tested the action of a trans-acting factor, hnRNP A2, on GLUT1 gene expression. We show that a cytoplasmic-localizing isoform of hnRNP A2 binds human GLUT1 RNA by gel-shift assay and by UV-crosslinking. Finally, over-expression of the hnRNP A2 isoform inhibited GLUT1 reporter expression in GBM-T98G cells. These results identify the AURE cis element in human GLUT1 mRNA and show that hnRNP A2 acts on GLUT1 mRNA to inhibit expression of GLUT1 in a brain cancer cell line.
Elsevier