Involvement of miR-190b in Xbp1 mRNA Splicing upon Tocotrienol Treatment |
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Authors: | Roberto Ambra Sonia Manca Guido Leoni Barbara Guantario Raffaella Canali Raffaella Comitato |
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Institution: | Council for Agricultural Research and Economics—Research Centre for Food and Nutrition, via Ardeatina 546, 00178 Rome, Italy; (R.A.); (S.M.); (G.L.); (B.G.); (R.C.) |
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Abstract: | We previously demonstrated that apoptosis induced by tocotrienols (γ and δT3) in HeLa cells is preceded by Ca2+ release from the endoplasmic reticulum. This event is eventually followed by the induction of specific calcium-dependent signals, leading to the expression and activation of the gene encoding for the IRE1α protein and, in turn, to the alternative splicing of the pro-apoptotic protein sXbp1 and other molecules involved in the unfolded protein response, the core pathway coping with EndoR stress. Here, we showed that treatment with T3s induces the expression of a specific set of miRNAs in HeLa cells. Data interrogation based on the intersection of this set of miRNAs with a set of genes previously differentially expressed after γT3 treatment provided a few miRNA candidates to be the effectors of EndoR-stress-induced apoptosis. To identify the best candidate to act as the effector of the Xbp1-mediated apoptotic response to γT3, we performed in silico analysis based on the evaluation of the highest ∆ in Gibbs energy of different mRNA–miRNA–Argonaute (AGO) protein complexes. The involvement of the best candidate identified in silico, miR-190b, in Xbp1 splicing was confirmed in vitro using T3-treated cells pre-incubated with the specific miRNA inhibitor, providing a preliminary indication of its role as an effector of EndoR-stress-induced apoptosis. |
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Keywords: | endoplasmic reticulum stress miR-190b apoptosis tocotrienol |
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