Figure 1.
(A) Schematics of mouse mutations in Utx. Included are annotations and locations of where the protein would be mutated. Two Utx mutant alleles included a gene trap in intron 3 (XUtxGT1) and a gene trap/floxed exon 3 (XUtxGT2fl). A UTX protein annotation is illustrated at the top to indicate to positions of Utx alleles. A germline Cre recombinase deleted exon 3 in the XUtxGT2fl background to create XUtxGT2Δ. Additionally, the gene trap of XUtxGT2fl was excised with Flp recombinase to create a standard floxed exon 3 (XUtxfl) and Cre recombination created XUtxΔ. (B) Western blotting of E18.5 liver demonstrates a complete loss of UTX in XUtxGT1 YUty+ lysates. RbBP5 was used as a loading control. (C) Western blotting of E10.5 whole embryo demonstrates a complete loss of UTX in XUtxΔ YUty+ and XUtxΔ XUtxΔ lysates. RbBP5 was used as a loading control. (D) Western blotting of E12.5 primary MEFs demonstrates a reduction of UTX in XUtxGT2fl YUty+ and XUtxGT2fl XUtxGT2fl lysates. RbBP5 was used as a loading control.
Figure 2.
Hemizygous male Utx mutant mice are runted.
(A) Hemizygous male Utx mutant mice are runted in size. Wild type male XUtx+ Y+ mice are displayed next to hemizygous XUtxGT1 Y+ mice. (B) The hemizygous mice exhibit a smaller size throughout adulthood.
Table 1.
Genotype frequencies of Utx and Uty mutant mice.
Figure 3.
Homozygous female Utx mutant embryos have mid-gestational developmental delay.
(A) Compared to controls (A-i and A-v), homozygous female E10.5 XUtxGT1 XUtxGT1 (A-ii) and XUtxGT2Δ XUtxGT2Δ (A-vi) embryos have some developmental delay including smaller size, underdeveloped hearts (white arrows), and open neural tube in the head (arrowheads). More severe embryos resemble the size and features of E9.5 embryos with cardiac abnormalities and peri-cardial edema (A-iii, vii, red arrows). Hemizygous male XUtxGT1 YUty+ embryos appear phenotypically normal at this stage (A-iv). The XUtxGT1 and XUtxGT2Δ alleles fail to complement as female XUtxGT1 XUtxGT2Δ embryos have identical phenotypes to homozygotes (A-viii). (B) At E10.5, homozygous XUtxGT1 XUtxGT1 female embryos exhibit either normal yolk sac vasculature with a reduction in red blood cells (B-ii) or have a completely pale yolk sac with unremodeled vascular plexus (B-iii).
Figure 4.
UTX and UTY have essential, redundant functions in embryonic development.
(A) Schematic of mouse mutation in Uty. The Uty gene trap YUtyGT is located in intron 4. Protein annotation is illustrated at the top to denote the location of the gene trap within the Uty coding sequence. (B) Quantitative RT-PCR downstream of the gene trap (exon 15) from tail RNA of X+ YUtyGT mice demonstrates essentially no mutant RNA. (C) XUtxGT2Δ YUtyGT males (C-iii, iv) have identical phenotypes to XUtxGT2Δ XUtxGT2Δ females (Figure 3A-vi, vii). Arrowheads denote open neural tube in the head, while white and red arrows denote moderate and more severe cardiac phenotypes.
Figure 5.
UTX and UTY redundancy is essential for progression of cardiac development.
(A) Similar sized Utx heterozygous (i), Utx homozygous (ii), Utx hemizygous (iii), or Utx/Uty compound hemizygous (iv) embryos were analyzed in more detail for cardiac developmental abnormalities. Frontal views of the respective hearts of these embryos revealed that Utx homozygotes and Utx/Uty compound hemizygotes (A-vi, viii) have smaller hearts that have not completed looping relative to Utx heterozygotes (A-v) or hemizygotes (A-vii). A white dashed line was drawn at an identical angle in all panels to illustrate the failure of hearts to loop around in alignment with this appropriate plane. Only control and Utx hemizygous embryos (A-v, vii) have initiated the formation of the interventricular groove (white arrows), indicative of early interventricular septum development. (B) Transverse sections of E10.5 XUtxGT2Δ XUtxGT2Δ (B-ii) and XUtxGT2Δ YUtyGT (B-iv) embryos reveal smaller heart size with defects in ventricular myocardial trabeculation and organization. The control and Utx hemizygous hearts initiated the formation of the interventricular septum (B-i, iii, IVS, black arrow), while other mutant combinations (B-ii, iv) have not (red asterisk). RA and LA = Right and Left Atrium, and RV and LV = Right and Left Ventricle. (C) More magnified images further illustrate the narrowing of the ventricular wall (red scale) and the lack of myocardial cells and structure in Utx homozygotes and Utx/Uty compound hemizygotes (Epi = epicardium, MC = myocardium, Endo = Endocardium).
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).
Figure 7.
UTX and UTY associate in common protein complexes and are capable of H3K27 demethylase independent gene regulation.
(A) Co-transfection of HA-UTX with Flag-UTX or Flag-UTY demonstrates that HA-UTX can immunoprecipitate with both Flag-UTX and Flag-UTY. (B) Immunoprecipitation of Flag-UTX and Flag-UTY reveal interaction with RBBP5, a component of the H3K4 methyl-transferase complex. Flag vector transfection was used as a negative control for immunoprecipitation. (C) Fnbp1, a gene targeted directly by UTX, has intermediate downregulation in XUtx− YUty+ MEFs (68% of WT, t-test p-value = 0.002), but was further compromised in XUtx− XUtx− (42% of WT, t-test p-value relative to XUtx− YUty+ = 0.001) and XUtx− YUty− (48% of WT, t-test p-value relative to XUtx− YUty+ = 0.02, N>4 independent MEF lines per genotype) MEFs. MEFs were generated from the XUtxGT2Δ and YUtyGT alleles. (D) Fnbp1 is similarly mis-expressed in XUtxGT2fl allelic combinations of E12.5 MEFs. XUtx− XUtx− and XUtx− YUty− MEFs significantly differ from XUtx− YUty+ MEFs (t-test p-value = 0.05 and 0.02 respectively, N>4 independent MEF lines per genotype). (E) H3K27me3 ChIP was performed on E12.5 XUtx+ YUty+ control (green) and XUtx− XUtx− (red) MEFs. An IgG antibody control is indicated in grey. Quantitative PCR for the ChIP was performed over a negative control region (an intergenic region) as well as a positive control (HoxB1). Fnbp1 failed to accumulate H3K27me3 in XUtx− XUtx− MEFs (t-test p-value = 0.5, N = 4 independent MEF lines per genotype). (F) H3K4me3 ChIP was performed on E12.5 XUtx+ YUty+ control (green) and XUtx− XUtx− (red) MEFs. An IgG antibody control is indicated in grey. Quantitative PCR for the ChIP was performed over a negative control region (intergenic region) as well as a positive control (Npm1). The WT Fnbp1 promoter exhibited significant H3K4me3 accumulation, which was reduced in XUtx− XUtx− MEFs (t-test p-value = 0.005, N = 3 independent MEF lines per genotype).
Figure 8.
UTY associates with BRG1 and heart transcription factors, and regulates downstream ANF gene expression.
(A) Myc-UTY was co-transfected with a Flag vector control or Flag BRG1 and immunoprecipitated with Flag-Agarose beads. Myc-UTY specifically immunoprecipitates with Flag-BRG1. (B) Myc-UTY was co-transfected with the Flag vector control or Flag-NKX2–5. Myc-UTY was co-immunoprecipitated by Flag-NKX2–5. (C) ANF:Luciferase reporter assay. HEK293T were transfected with the reporter ANF:Luciferase construct alone (-), with NKX2–5, with NKX2–5 and UTY, or with NKX2–5 and UTX. Reporter activity was significantly enhanced with the addition of UTY (t-test p-value = 0.01). Right panel illustrates the comparison of UTY versus UTX enhancement of NKX2–5 driven ANF expression. N = 3 independent transfections per group. (D) Anf expression was analyzed from E10.5 heart RT-PCR of various XUtxGT2Δ and YUtyGT allelic combinations. A moderate, but not significant downregulation of ANF was observed in XUtx− YUty+ hearts (76% of WT, t-test p-value = 0.06), but was significantly compromised in XUtx− XUtx− (52% of WT, t-test p-value relative to XUtx+ YUty+ = 0.005) and XUtx− YUty− (57% of WT, t-test p-value relative to XUtx+ YUty+ = 0.02, N>4 per genotype) hearts.