nfluences the process of replicative senescence, whereby cells reach a state in which they remain metabolically active but appear incapable of further division. Cellular senescence is triggered by stimuli such as aberrant proliferative signals or damage to DNA or other macromolecules. In agreement with earlier observations that p16 levels increased with aging, and that p16 overexpression triggers a senescent phenotype recent discoveries support the notion that cellular senescence plays a direct role in mammalian aging. In mouse models, p16 deficiency partially prevented the age-induced decline in cell proliferation 
and tissue function. Given the prominent role of p16 in cancer and senescence/ aging, there is much interest in understanding the molecular regulators of p16 expression as triggered by 16293603 both environmental signals and developmental cues. Transcriptionally, CDC6 was reported to silence the INK4a/ARF locus by heterochromatinization linked to DNA replication. In addition, p16 expression was shown to be induced by transcription factors such as Ets1, Ets2, and JunB and repressed by transcription factors 18645012 such as Id1 and Id3 and by Bmi-1. Posttranscriptionally, the splicing of p16 mRNA was proposed to be influenced by ASF/ SF2 and the p16 mRNA stability reduced by RNA-binding proteins hnRNP A1, hnRNP A2, and AUF1. RBPs constitute a major class of major trans acting factors that associate with RNAs and regulate gene expression after transcription by influencing processes such as pre-mRNA splicing and maturation, and mRNA transport, storage, stability, and translation. The other major group of trans acting, posttranscriptional regulatory factors are microRNAs, a collection of short, single-strand, noncoding RNAs that have been described in a wide variety of organisms. The molecular details of miRNA-mediated suppression of gene expression are rapidly emerging. miRNAs are assembled into RNA-induced silencing complexes, which recruit a target mRNA to processing bodies that function as cytoplasmic foci of mRNA degradation and translational repression. Depending upon the degree of complementarity of the mRNA-miRNA complex, miRNAs can promote the cleavage of the target mRNA, an occurrence that is favored by extensive complementarity with the mRNA, or they can suppress mRNA translation but not mRNA degradation in instances of less complete base-pairing. However, the precise mechanisms by which miRNAs inhibit translation remains controversial. Some studies indicate that miRNAs block the initiation of translation, in some instances triggering the formation of large ribonucleoprotein `pseudo-polysomes’, yet others miR-24 Blocks p16 Translation suggest that miRNAs suppress post-initiation steps by repressing translational elongation, by promoting ribosome drop-off or by inhibiting termination. It is likely that 503468-95-9 multiple mechanisms are operating that depend on the nature of the miRNA, the untranslated regions, and the cellular context. An integrated model of miRNA action was proposed whereby miRNA action involved both translational suppression and accelerated decay. Here, we have identified miR-24-2 as a microRNA that suppresses p16 translation in cultured human cells. Modulation of miR-24 levels by transfection of either premiR-24 or antisense -miR-24 directly affected p16 expression levels by altering the engagement of p16 mRNA with the translation machinery and consequently p16 biosynthesis. Our results are consistent with a role for miR-24 in r