microRNA-494 promotes cellular senescence in human diploid fibroblasts by targeting several genes

We recently identified miR-494 up-regulation as a component of the program leading to cellular senescence of human diploid IMR90 fibroblasts [1]. To identify miR-494 targets, we used 2D-DIGE coupled to mass spectrometry analysis to profile protein changes induced by overexpression of miR-494 in IMR90 cells. miR-494 induced robust perturbation of the IMR90 proteome by significantly (p≤0.05) affecting a number of proteins. Combination of mass spectrometry-based identification of down-regulated proteins and bioinformatic prediction analysis for miR-494 binding sites on the relevant mRNAs, identified 26 putative targets of miR-494, with 7 of them featuring evolutionary conservation of miR-494 binding site. Functional miR-494 binding site were confirmed for hnRNPA3, PDIA3, RAD23B, and SYNCRIP. siRNA-mediated knockdown of hnRNPA3 and, to a lesser extent, RAD23B mirrored the senescent phenotype induced by miR-494, blunting cell proliferation and causing increase of SA-β-gal and DNA damage. Reintroduction of hnRNPA3 or RAD23B slowed the appearance of miR-494-induced senescent phenotype in IMR90 cells. Overall, these findings identify novel miR-494 direct targets involved in senescence. References: [1]Faraonio R et al. Cell Death Differ. 2012 Apr;19(4):713- 21. doi: 10.1038/cdd.2011.143. Epub 2011 Nov 4