Fig 2: NAT10 inhibitor Remodelin enhances the sensitivity of cells expressing WT MORC2, but not K767R mutant MORC2, to MMS and IR. (A–D) MORC2 KO MCF-7 and BT549 cells stably expressing Flag-MORC2 or Flag-MORC2 K767R were treated with increasing doses of MMS (A) or IR (B) and subjected to colony formation survival assays. DMSO or 5 µM Remodelin was added to culture medium. Representative images of survival colonies are shown in A and B, and corresponding quantitative results are shown in C and D.

Fig 3: NAT10 acetylates MORC2 at K767. (A, B) Cells were treated with 5 µM TSA and 5 mM NAM for 6 h. Lysates were subjected to IP assays with control IgG, an anti-MORC2 (A) or anti-Ac-K (B) antibody, followed by immunoblotting analysis with the indicated antibodies. (C) Cells were treated with or without 5 mM NAM or 5 µM TSA alone or in combination for 6 h and subjected to IP and immunoblotting analysis with the indicated antibodies. MORC2 acetylation levels were normalized to those of total MORC2 protein. (D) Analysis of MORC2 acetylation sites in publicly available databases. (E, F) HEK293T cells stably expressing pCDH, Flag-MORC2, and Flag-MORC2 K767R were treated or without NAM at the indicated concentrations for 6 h (E) or 5 mM NAM for the indicated times (F). IP and immunoblotting analyses were performed with the indicated antibodies. (G) Alignment of MORC2 protein sequence across different species. (H) HEK293T cells stably expressing pCDH and Flag-MORC2 (WT, K767R and K767Q) were treated with or without 5 mM NAM for 6 h and subjected to IP and immunoblotting analyses with the indicated antibodies. (I) MCF-7 and BT549 cells were treated with or without 5 mM NAM for 6 h and subjected to IP and immunoblotting analyses with the indicated antibodies. MORC2 K767Ac levels were normalized to those of total MORC2 protein. (J) MCF-7 and BT549 cells were transfected with pCDH, HA-NAT10, or HA-NAT10 G641E. After 48 h of transfection, lysates were subjected to IP and immunoblotting analysis. (K–M) HEK293T cells stably expressing pCDH and Flag-MORC2 (K), MCF-7 (L), or BT549 (M) cells were transfected with negative control siRNA (siNC) or two siRNAs targeting NAT10 (siNAT10). After 48 h of transfection, cells with treated with or without 5 mM NAM for 6 h and subjected to IP and immunoblotting analysis. In L, cells were pretreated with or without 5 µM Remodelin for 3 h prior to NAM treatment. (N) Purified His-MORC2 was incubated with or without purified NAT10, 2 mM acetyl-CoA in reaction buffer at 37°C for 1 h. MORC2 K767Ac was detected by immunoblotting. His-MORC2 was visualized by Coomassie blue staining. (O) Purified His-MORC2 (WT and K767R) were incubated with or without purified NAT10, 2 mM acetyl-CoA in reaction buffer at 37°C for 1 h. MORC2 K767Ac was detected by immunoblotting. His-MORC2 was visualized by Coomassie blue staining.

Fig 4: NAT10 regulates H3T11P, CDK1, and Cyclin B1 expression through MORC2 K767Ac. (A–D) MCF-7 cells were transfected with siNC or two siNAT10s. After 48 h of transfection, cells were treated with or without 1 mM MMS or 6 Gy IR for 2 h and then subjected to immunoblotting (A-B) and qPCR analysis (C-D). (E–H) MCF-7 cells were pretreated with or without 5 μM Remodelin for 3 h, followed by treatment with or without 1 mM MMS or 6 Gy IR for another 2 h. Immunoblotting (E, F) and qPCR analyses (G-H) were performed as indicated. (I–L) MORC2 KO MCF-7 cells stably expressing Flag-MORC2 and Flag-MORC2 K767Q were transfected with siNC or two siNAT10s. After 48 h of transfection, cells were treated with or without 1mM MMS or 6 Gy IR for 2 h and then subjected to immunoblotting (I and J) and qPCR analysis (K and L). (M–P) MORC2 KO MCF-7 cells expressing Flag-MORC2 and Flag-MORC2 K767Q were pretreated with or without 5 μM Remodelin for 3 h, followed by treatment with or without 1 mM MMS or 6 Gy IR for another 2 h. Immunoblotting (M and N) and qPCR analyses (O and P) were performed as indicated.

Fig 5: DNA-damaging agents stimulate MORC2 K767Ac in a NAT10-dependent manner. (A) MCF-7 and BT549 cells were treated with or without 1 mM MMS, 1 mM H2O2, 1 μM ADR, 100 μM CDDP or 6 Gy IR. After 2 h of treatment, lysates were subjected to IP and immunoblotting analyses with the indicated antibodies. MORC2 K767Ac levels were normalized to those of total MORC2 protein. (B, C) HEK293T cells were treated with or without 1mM MMS (B) or 6 Gy IR (C). After 2 h of treatment, cells were stained with MORC2 K767Ac antibody (green) and γH2AX (red). DNA was counterstained with DAPI (blue). For peptide blocking assays, K767 acetylated peptide (final concentration: 0.1 μg/μL) was added into the diluted K767Ac antibody. Quantitative results for K767Ac- and γH2AX-positively stained cells are shown in the right panel. ***, P < 0.01, **, P < 0.01. Scale bar, 25 μm. (D, F) Cells were transfected with siNC or two siNAT10s. After 48 h of transfection, cells were treated with or without 1mM MMS or 6 Gy IR for 2 h and harvested for IP and immunoblotting analysis with the indicated antibodies. (G) WT and SIRT2 KO MCF-7 cells were treated with or without 1 mM MMS or 6 Gy IR for 2 h and harvested for IP and immunoblotting analysis with the indicated antibodies. MORC2 K767Ac levels were normalized to those of total MORC2 protein. (H–M) MCF-7 and BT549 cells were treated with or without 1mM MMS or 6 Gy IR for 2 h. IP and immunoblotting analysis was conducted with the indicated antibodies. (N) MCF-7 cells were transfected with HA-NAT10 and Flag-MORC2. After 48 h of transfection, cells were treated with or without 1 mM MMS or 6 Gy IR for 2 h and stained with anti-Flag (green) or anti-HA (red) antibody. DNA was counterstained with DAPI (blue). Typical co-location between NAT10 and MORC2 was indicated by arrows. Quantitative results for cells with NAT10 nucleoplasm translocation are shown in the right panel. ***P < 0.01, **P < 0.01. Scale bar, 2.5 μm.