UTX and UTY Demonstrate Histone Demethylase-Independent Function in Mouse Embryonic Development (original) (raw)
Figure 6
Human and mouse UTY have no H3K27 demethylase activity.
(A) HEK293T cells were transfected with Flag-tagged C-terminal human (H) and mouse (M) UTX and UTY constructs. The C-terminal fragments span AA 880–1401 in human UTX (Figure S6) and include the corresponding regions in mouse UTX. Transfected cells (white arrows) over-expressing H-UTX and M-UTX (Flag immunofluorescence, green pseudo-color) exhibited global loss of H3K27me3 immunofluorescence (red pseudo-color). Cells transfected with H-UTY and M-UTY C-terminal constructs did not demethylate H3K27me3. (B) H3K27me3 demethylase assay of UTX and UTY mutant constructs. H-UTX H1146A contains a point mutation in a residue that was previously reported as defective in H3K27 demethylation. Cells expressing H-UTX H1146A had no loss of H3K27me3. Mouse UTY has a Y to C amino acid change that corresponds to position 1135 in human UTX. This UTX residue is predicted to regulate H3K27me3 binding and demethylation. Expression of H-UTX Y1135C failed to demethylate H3K27me3. Mouse UTY also has a T to I amino acid change that corresponds to position 1143 in human UTX that is predicted to regulate binding of ketoglutarate in the demethylase reaction. Expression of H-UTX T1143I failed to demethylate H3K27me3. Correction of these two altered residues in mouse Uty (M-UTY-C947Y, I955T) failed to recover H3K27me3 demethylase activity. (C) Alignment of the JmjC domains of human/mouse UTX human UTY, mouse UTY, and human/mouse JMJD3. UTY non-conservative substitutions are indicated by white boxes and residues of interest are labeled with red asterisks. The UTX mutations that were analyzed are listed above the alignment, while JMJD3 mutations are listed below the alignment. (D) HEK293T cells were transfected with C-terminal UTX and UTY constructs or full-length mouse JMJD3 constructs carrying various AA substitutions. Medium-high expressing cells (N≥100 cells scored for each experiment) were scored for any visible reduction in H3K27me3 levels relative to nearby untransfected cells. 100% of WT H-UTX, M-UTX and M-JMJD3 expressing cells had observable H3K27me3 demethylation. The negative controls of H-UTX H1146A, M-JMJD3 H1388A, and M-JMJD3 with deletion of the JmjC domain had no visible H3K27me3 demethylation (0% of cells). Wild type H-UTY and M-UTY had 0% of cells with detectable demethylation. Of the point mutations in UTY predicted to affect H3K27me3, only mutation of H-UTX Y1135C and T1143I with corresponding M-JMJD3 Y1377C and T1385I had no cells with any detectable H3K27 demethylation (0%). (E) Stereo view of the active site of human UTX (PDB ID: 3AVR). The corresponding residues in mouse UTY are also indicated in parentheses. The figure was prepared with the program Pymol (Schrodinger LLC).