Figure 1. PRMT5 inhibition leads to KAT5 exon skipping and altered Tip60-EP400 complex composition.

(A) Cell viability assay (CellTiter-Glo) of MKL-1 cells treated with the PRMT5 inhibitor JNJ-64619178 for 5, 8, and 11 d at indicated doses. (B) MKL-1 cells were treated for 4 d with serially diluted concentrations of JNJ-64619178, followed by immunoblotting with the indicated antibodies. (C) MKL-1 cells were treated with DMSO, 12 nM PRMT5 inhibitor (JNJ-64619178), and 111 nM type I PRMT inhibitor (MS023) for 3 d, followed by immunoblotting with the indicated antibodies. The arrow indicates a reduced full-length Tip60⍺ protein level. (D) MKL-1 cell line with Dox-inducible EP400 shRNA was treated with DMSO, 111 nM type I PRMT inhibitor (MS023), 12 nM PRMT5 inhibitor (JNJ-64619178), or Dox for 3 d. Whole-cell lysates were immunoprecipitated with MAX or EP400 antibodies and immunoblotted with indicated antibodies. Arrows indicate the increased incorporation of the catalytically impaired Tip60β isoform protein into the ST-MYCL-EP400 complex upon PRMT5 inhibition. Both short and long exposures of the blot are shown to visualize abundant Tip60β and low-abundance Tip60α isoforms. Under these immunoprecipitation conditions, the low basal level of Tip60α remained near detection limits.

Source data are available for this figure.