Fig. 2: PQBP5 is essential for nucleolar assembly of fibrillarin and nucleolin.

a Structure of the PQBP5, fibrillarin and nucleolin knockdown vectors. The target sequences with the loop region were subcloned between the BamHI and HindIII sites. b Western blot analysis of HeLa cells transfected transiently with plasmids expressing PQBP5, fibrillarin, and nucleolin shRNAs. These shRNAs reduced the levels of expression of PQBP5, fibrillarin, and nucleolin to nearly 30% of the levels in untransfected cells. The similar experiment was repeated three times. c Immunocytochemistry showing the levels of expression of each target protein in cells transfected transiently with plasmids expressing PQBP5, fibrillarin, and nucleolin shRNAs. The expression of each target protein was almost completely suppressed in transfected cells. Knockdown of PQBP5 induced dispersion of fibrillarin and nucleolin. Fibrillarin knockdown did not affect the distribution of the other proteins. Nucleolin knockdown affected the distribution of fibrillarin but not of PQBP5. The box plot shows median, 25–75th percentile, and whiskers representing data outside the 25–75th percentile range. Tukey’s HSD test was used for multiple comparisons. P < 0.0001 in all comparisons by GraphPad Prism. d Hierarchy of PQBP5, nucleolin, and fibrillarin determined by knockdown experiments.