Cis-acting elements in its 3' UTR mediate post-transcriptional regulation of KRAS.
Multiple RNA-binding proteins and non-coding RNAs, such as microRNAs (miRNAs), are involved in post-transcriptional gene regulation through recognition motifs in the 3' untranslated region (UTR) of their target genes. The KRAS gene encodes a key signaling protein, and its messenger RNA (mRNA) contains an exceptionally long 3' UTR; this suggests that it may be subject to a highly complex set of regulatory processes. However, 3' UTR-dependent regulation of KRAS expression has not been explored in detail. Using extensive deletion and mutational analyses combined with luciferase reporter assays, we have identified inhibitory and stabilizing cis-acting regions within the KRAS 3' UTR that may interact with miRNAs and RNA-binding proteins, such as HuR. Particularly, we have identified an AU-rich 49-nt fragment in the KRAS 3' UTR that is required for KRAS 3' UTR reporter repression. This element contains a miR-185 complementary element, and we show that overexpression of miR-185 represses endogenous KRAS mRNA and protein in vitro. In addition, we have identified another 49-nt fragment that is required to promote KRAS 3' UTR reporter expression. These findings indicate that multiple cis-regulatory motifs in the 3' UTR of KRAS finely modulate its expression, and sequence alterations within a binding motif may disrupt the precise functions of trans-regulatory factors, potentially leading to aberrant KRAS expression.
['Kim|Minlee|M|', 'Kogan|Nicole|N|', 'Slack|Frank J|FJ|']
D020413:3' Untranslated Regions D001483:Base Sequence D015972:Gene Expression Regulation, Neoplastic D017930:Genes, Reporter D006801:Humans D009369:Neoplasms D011401:Promoter Regions, Genetic D016283:Proto-Oncogene Proteins p21(ras) D012323:RNA Processing, Post-Transcriptional D012045:Regulatory Sequences, Nucleic Acid D014407:Tumor Cells, Cultured
post-transcriptional regulation KRAS microRNAs (miRNAs) miR-185 3′ UTR