Post-transcriptional regulation of glucose transporter-1 by an AU-rich element in the 3'UTR and by hnRNP A2.
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 30 nt 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 3'UTR. 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.
Griffin
Mary E
ME
Veterans Administration Research Service, White River Junction, VT 05009-0001, USA.
Hamilton
B JoNell
BJ
Roy
Kristen M
KM
Du
Min
M
Willson
Alicia M
AM
Keenan
Benjamin J
BJ
Wang
Xiao Wei
XW
Nichols
Ralph C
RC
D020413:3' Untranslated Regions / Q000235:genetics / Q000378:metabolism*; D000241:Adenosine / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D003593:Cytoplasm / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter / Q000235:genetics; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism; D051272:Glucose Transporter Type 1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D015854:Up-Regulation; D014529:Uridine / Q000235:genetics / Q000378:metabolism
D020413:3' Untranslated Regions; D051272:Glucose Transporter Type 1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D009004:Monosaccharide Transport Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C495677:SLC2A1 protein, human; C439768:hnRNP A2; D000241:Adenosine; D014529:Uridine