Figure 5.
DDX6 represses tumor suppressor TXNIP in AML cells. (A) Fourteen DDX6 targeting candidates were identified by overlapping DDX6-upregulated mRNAs and DDX6-bound mRNAs found in K562 and HepG2 cells. The enhanced crosslinking immunoprecipitation of DDX6 conducted for K562 and HepG2 cells were obtained from ENCODE (accession numbers ENCSR141OIM and ENCSR893EFU). The transcriptomics data of K562 and HepG2, transfected with shDDX6, were also received from ENCODE (accession numbers ENCSR147ZBD and ENCSR119QWQ). (B) An increased expression of TXNIP mRNA in HepG2 and K562 cells after the DDX6 knockdown from the transcriptomics analysis in panel A. (C) Immunoblots showing the upregulated protein level of TXNIP after the DDX6 knockdown in MOLM13 cells. (D) Quantification of western blot data shown in panel C. The bar graph showing data as mean ± standard error of the mean; n = 5 independent experiments; ∗P < .05, ∗∗P < .01, ∗∗∗P < .001; 2-tailed Student t test. (E) The binding peaks of DDX6 in TXNIP mRNA transcript found in enhanced crosslinking immunoprecipitation of DDX6 conducted in K562 (accession number ENCSR141OIM). (F) The 3′ UTR region of TXNIP containing 3 DDX6 binding sites was inserted downstream of the FL CDS in the reporter plasmid, pGL-FL, generating pGL-FL-TXNIP-DDX6. In the pGL-FL-TXNIP-noDDX6 construct, 3 DDX6 binding sites were removed. Dual-luciferase reporter assays were conducted for TXNIP using HEK293T cells without (G) or with DDX6 overexpression (H). (I) A proposed model illustrating a functional link between miR-148a-3p and DDX6 in promoting the survival of myeloid leukemia cells.