FIGURE 2.

MiR‐155 inhibits DEPTOR with secondary activation of mTOR in B lymphoma cell lines. (A) A model for the interactions between miR‐155 and the 3'UTR of DEPTOR. The RNAhyb program predicts a binding site starting at 480 nucleotides after the stop codon. Upper: sequence of the target site at the 3'UTR of DEPTOR; Lower: sequence of miR‐155. The 5' and 3' ends are specified. (B) Confirmation of the binding site for miR‐155 with luciferase assay in U2932 cells. Y‐axis: relative luciferase activity. X‐axis, from left to right: U2932 cells transfected with miR‐155 and DEPTOR, with mt‐miR‐155 and DEPTOR, with miR‐155 and mt DEPTOR, and with mt miR‐155 and mt DEPTOR (wt: wild type; mt mutant). (C) Induction of phosphorylated mTOR (p‐mTOR) by miR‐155 in BJAB cells. An EGFP+ vector is used to over‐express miR‐155. After transfection and sorting, >90% of the cells are EGFP+. Overexpression of miR‐155 reduced the level of DEPTOR with secondary increase in the level of p‐mTOR. (D) A model for induction of p‐mTOR by miR‐155 in gastric diffuse large B‐cell lymphoma resistant to H. pylori eradication therapy. In the mTOR complex, DEPTOR together with either RAPTOR in mTORC1 or RICTOR in mTORC2 inhibit the activity of mTOR. In the presence of increased miR‐155 and decreased DEPTOR, the inactive complex dissociates into active form. D: DEPTOR and R: RAPTOR or RICTOR