Fig. 3: Bufalin promotes SDC4 interaction with DDX23 to regulate genomic instability.

a Scatter plot depicted SDC4 interactome. Log₂ heavy (H) / light (L) ratios of the quantified proteins were shown on x-axis and log₁₀ signal intensity (combined for heavy and light peptides) on the y-axis. b Quantification of SDC4 and DDX23 by 2-D HPLC LTQ/Orbitrap MS. Peaks with light-labeled (gray) and heavy-labeled (red) peptides were presented. VSMSSTVQGSNIFER and MIDMGFEPDVQKILEHMPVSNQK were peptides from SDC4 and DDX23, respectively. (R, Arginine; K, Lysine) m/z, mass/charge ratio. c Bufalin promoted the SDC4 binding to DDX23. Western blot of co-immunoprecipitation was performed with anti-SDC4 or anti-DDX23 antibodies. d Structure outline of SDC4 (upper panel). SDC4 interacts with DDX23 through its 1-170 amino acids peptide (lower panel). e Bufalin increased the number of γH2AX foci, which was blocked by siSDC4. Negative control or siSDC4 HepG2 cells were treated with/without bufalin, followed by γH2AX foci and DAPI staining. f, g siSDC4 or siDDX23 reversed bufalin-dependent cell viability decrease. Cells transfected with siSDC4, siDDX23 or negative control were treated with bufalin for 24 h. Cell viability was measured by MTT assay. h Cells transfected with siSDC4, siDDX23 or negative control were incubated with/without bufalin (10 nM) for 48 h. Wound area was calculated. Data are representative of three independent experiments. *P < 0.05, **P < 0.01 vs. control group; ns, not significant by ANOVA with Student’s t-test.