BioProject

Regulation of gene expression at the post-transcriptional level plays an indispensable role during TGFbeta-induced EMT and metastasis. More...

Regulation of gene expression at the post-transcriptional level plays an indispensable role during TGFbeta-induced EMT and metastasis. This regulation involves a transcript-selective translational regulatory pathway in which a ribonucleoprotein (mRNP) complex, consisting of heterogeneous nuclear ribonucleoprotein E1 (hnRNP E1) and eukaryotic elongation factor 1A1 (eEF1A1), binds to a 3’-UTR regulatory BAT (TGFβ activated translation) element and silences translation of Dab2 and ILEI mRNAs, two transcripts which are involved in mediating EMT. TGFbeta activates a kinase cascade terminating in the phosphorylation of hnRNP E1, by isoform-specific stimulation of protein kinase B/Akt2, inducing the release of the mRNP complex from the 3’-UTR element, resulting in the reversal of translational silencing and increased expression of Dab2 and ILEI transcripts. We adopted a combinatorial approach involving polysome profiling and RIP-Chip analyses using hnRNP E1 and filtered the array data based on the regulatory mechanism of Dab2 and ILEI. This led to the identification and validation of a cohort of target mRNAs that follow the same pattern of regulation as Dab2 and ILEI. Overall design: To identify potential target mRNA transcripts that are translationally regulated by hnRNP E1 in a TGF-beta-dependent manner, we adopted a combinatorial approach involving expression profiling analyses and RNA immunoprecipitation analysis (RIP-Chip). We performed a screen using: 1) total mRNA and 2) RNA isolated from monosomal (non-translating) versus polysomal (translating) fractions from TGF-beta-treated (24 h) and non-treated NMuMG cells and from the hnRNP E1 knockdown derivative (E1KD), that undergo constitutive EMT even in the absence of TGF-beta. In addition, we screened for transcripts that selectively interact with hnRNP E1 in NMuMG cells under unstimulated conditions and subsequently lose their temporal association following TGF-beta stimulation. The samples were individually hybridized to Affymetrix GeneChip® Mouse Genome 430 2.0 arrays. Less...