Fig 1: Loss of CPSF6 expression globally shortens the 3’UTR of cellular mRNAs. (A) A549 WT, NT#H1, CPSF6-KO#B4, CPSF6-KO#B7, and CPSF6-KO#C8 cells were lysed, and proteins were analyzed by Nu-PAGE, followed by western blot using anti-CPSF6, anti-CPSF5, anti-CPSF7, and anti-GAPDH antibodies. Experiments were repeated at least three times, and a representative image is shown. Graphs show the average densitometry quantification of three replicates with standard deviation. Significance was determined using ANOVA multiple comparisons tests; ***P < 0.001; ns, not significant. (B) Total RNA from CPSF6-KO and WT A549 cells was prepared, and polyadenylated transcripts were identified by PAC-seq, followed by APA analysis using PolyAMiner. (C) A549 WT, NT#H1, CPSF6-KO#B4, CPSF6-KO#B7, and CPSF6-KO#C8 cells were infected with increasing amounts of HIV-1-GFP for 24 or 48 h. Infection was assessed as the percentage of GFP-positive cells by flow cytometry. (D) WT and CPSF6-KO#B7 A549 cells were infected with HIV-1-GFP at an MOI of 2 for 48 h. Cells were fixed, permeabilized, and stained using the following antibodies: (i) anti-CPSF5 (red) and anti-CPSF6 (green); (ii) anti-SC-35 (red) and anti-CPSF6 (green); (iii) anti-LEDGF/p75 (red) and anti-CPSF6 (green); and (iv) anti-LEDGF/p75 (red) and anti-SC35 (green). Nuclei were stained with DAPI (blue). Scale bar, 10 µm. (E) Percentage of A549 cells containing CPSF6, CPSF5, or CPSF7 in nuclear speckles (condensates) upon HIV-1 infection (average of three independent experiments with standard deviation). Cells containing CPSF6, CPSF5, or CPSF7 in nuclear speckles were determined by visual examination of 200 cells. Significance was determined using unpaired t-test; ***P < 0.001; ns, not significant. APA, alternative polyadenylation; CPSF5, cleavage and polyadenylation specificity factor subunit 5; CPSF6, cleavage and polyadenylation specificity factor subunit 6; CPSF7, cleavage and polyadenylation specificity factor subunit 7; DAPI, 4’,6-diamidino-2-phenylindole; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; KO, knockout; LEDGF/p75, lens epithelium-derived growth factor; NT, non-targeting; PAC-Seq, Poly(A)-Click-Sequencing; UTR, untranslated region; WT, wild-type; hpi, hours post-infection.