The hypoxic proteome is influenced by gene-specific changes in mRNA translation.
OBJECTIVE
Hypoxia causes a rapid reduction in mRNA translation efficiency. This inhibition does not affect all mRNA species to the same extent and can therefore contribute significantly to hypoxia-induced differential protein expression. Our aim in this study was to characterize changes in gene expression during acute hypoxia and evaluate the contribution of regulation via mRNA translation on these changes. For each gene, the contribution of changes in mRNA abundance versus mRNA translation was determined.


METHODS
DU145 prostate carcinoma cells were exposed to 4h of hypoxia (<0.02% O2). Efficiently translated mRNAs were isolated by sedimentation through a sucrose gradient. Affymetrix microarray technology was used to evaluate both the transcriptional and translational contribution to gene expression. Results were validated by quantitative PCR.


RESULTS
One hundred and twenty genes were more than 4-fold upregulated by hypoxia in the efficiently translated fraction of mRNA, in comparison to only 76 genes at the level of transcription. Of the 50 genes demonstrating the largest changes in translation, 11 were found to be more than 2-fold over represented in the translated fraction in comparison to their overall transcriptional level. The gene with the highest translational contribution to its induction was CITED-2, which is a negative regulator of HIF-1 transcriptional activity.


CONCLUSIONS
Gene-specific regulation of mRNA translation contributes significantly to differential gene expression during hypoxia.
Koritzinsky
Marianne
M
Department of Radiation Oncology (MAASTRO Lab), Research Institute Growth and Development, Maastricht, The Netherlands.
Seigneuric
Renaud
R
Magagnin
Michaël G
MG
van den Beucken
Twan
T
Lambin
Philippe
P
Wouters
Bradly G
BG
D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D015870:Gene Expression; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism; D040081:Protein Array Analysis; D014176:Protein Biosynthesis; D020543:Proteome; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D020543:Proteome