Splicing promotes the nuclear export of β-globin mRNA by overcoming nuclear retention elements

Fusions of ftz fragments to full-length βG mRNA are cytoplasmic at steady state. (A) A schematic representation of the different constructs that were used in this figure. (B–E) Plasmids containing the indicated constructs were transfected into human U2OS cells. After 14–18 h, the cells were fixed, permeabilized, and stained for mRNA using a FISH probe directed against βG (B,C) or the MHC SSCR (D,E). The cells were imaged (B,D) and mRNA distribution in the cytoplasm and nucleus was quantified (C,E). Each bar represents the average and standard error of three independent experiments, with each experiment consisting of at least 30 cells. Scale bar = 20 µm.