Figure 2. The effects of MOS variants on protein expression and ERK1/2 activation in cells and oocytes.

1. The per million mapped reads (RPKM) values (extracted from GSE36552) showing the MOS expression level in human oocytes and early embryos (n = over 3 biological replicates).
2. The immunofluorescence images show the pERK1/2 (red) dynamics in immature (GV, n = 5), mature (MII, n = 10), and fertilized oocytes from unidentified control patients (n = 6), as well as in mature oocytes from patient 1 carrying homozygous MOS^Asn95Lys variants. pERK1/2 activation was inhibited after U0126 treatment (n = 6). FITC‐α‐tubulin (Green) and DAPI (blue) were used for co‐staining. Scale bar = 10 µm.
3. Western blot analysis of the MEK1/2 and ERK1/2 activation after transfection of FLAG‐tagged wild‐type MOS and identified MOS variants in HEK 293 cells.
4. Statistical analysis of the protein expression level of FLAG, pERK1/2, and pMEK1/2 (n = 2 technical replicates). The protein intensities were quantified by Image J software.
5. Diagram showing the experimental design, including procedure of MOS mRNAs injection and oocyte culture. GV oocytes were overexpressed via microinjection with wild‐type MOS or MOS variant mRNAs combined with mCherry mRNAs, followed by culture for 4 h in medium containing 2.5 µM milrinone.
6. Immunofluorescence of FLAG (green) and pERK1/2 (grey) in oocytes after injection of different MOS variant mRNAs combined with mCherry mRNAs. The signal of mCherry was directly captured after fixation, with DAPI staining for DNA visualization (blue). (n = over 30 oocytes in each group.) Scale bar = 10 µm.

Data information: In A and D, data are presented as mean ± SD. **P < 0.01, ***P < 0.001; ns., no significance (two‐way ANOVA with Tukey’s multiple comparisons test in D). Detailed P value as indicated.

Source data are available online for this figure.