Fig. 4

Candidate splicing factor knockdown results in sororin intron 1 retention leading to reduction of sororin protein levels. a Nuclear phenotype 72 h after candidate splicing factor or sororin knockdown in MDA-MB-231 and Hs578T cells. Scale bar = 50 μm. b Sororin intron 1 (i) and intron 2 (ii) retention 72 h after SNRPD2, SNRPD3 and NHP2L1 knockdown in Hs578T and MDA-MB-231 cells. Mean + stdev of 3 biological replicates. c Sororin intron 1 retention 72 h after knockdown of other splicing factor candidates in Hs578T and MDA-MB-231 cells. Mean + stdev of 3 biological replicates. d Confocal images of MDA-MB-231 cells 24 h after transfection with mScarlet, mScarlet tagged sororin (without introns) or mScarlet tagged sororin with intron 1 retained. mScarlet transfections were combined with GFP vectors to control for transfection efficiency. Scale bar = 100 μm. e Alternative splicing of sororin 24 h after transfection with different mScarlet-Sororin plasmids. Forward primer bound to mScarlet, reversed primer bound to sororin exon 2. f Sororin protein expression 24 h after co-transfection with mScarlet and GFP plasmids. Statistical significance was determined using ANOVA correcting for multiple testing. * p < 0.05, ** p < 0.01, *** p < 0.001