Fig. 5: MAT2A enhances SUMOylation and stabilization of SRF to facilitate PARN transcription.

A Co-IP analysis in MNNG/HOS and U-2OS cells showing that neither MAT2A nor SRF physically interacts with PARN. Immunoprecipitation with anti-MAT2A or anti-SRF antibodies followed by immunoblotting for PARN revealed no detectable interaction, indicating that PARN is not directly associated with MAT2A–SRF complexes. B qRT-PCR analysis showing that MAT2A knockdown significantly decreased MAT2A mRNA expression but had no effect on SRF transcript levels in MNNG/HOS and U-2OS cells (P < 0.001, ns: not significant). C Western blot analysis showing that SRF protein levels were markedly reduced following MAT2A knockdown, while MAT2A loss was confirmed in parallel. GAPDH served as loading control. D CHX chase assay demonstrating accelerated degradation of SRF protein in MAT2A-depleted cells compared with control cells, indicating that MAT2A positively regulates SRF protein stability. Cells were treated with CHX (100 μg/mL) and harvested at the indicated time points (0–8 h). E Western blot analysis showing that MAT2A knockdown caused no obvious changes in total or phosphorylated SRF (p-SRF) levels, suggesting that MAT2A does not significantly affect SRF phosphorylation status. F CO-IP analysis of SRF post-translational modifications in control and MAT2A-knockdown MNNG/HOS and U-2OS cells. MAT2A silencing markedly reduced SUMO2/3-conjugated SRF, while acetylated SRF (Ac-SRF) levels remained unchanged, suggesting that MAT2A specifically promotes SRF SUMOylation. Input controls confirmed equal loading of MAT2A, SRF, and GAPDH. Data are presented as mean ± SD from three independent experiments. *P < 0.05, **P < 0.01, **P < 0.001.