CR6-interacting factor-1 contributes to osteoclastogenesis by inducing receptor activator of nuclear factor κB ligand after radiation

Figure 3 CR6-interacting factor-1 is involved in the regulation of receptor activator of nuclear factor κB ligand expression after radiation. A: Western blot analysis of CR6-interacting factor-1 (Crif1) and receptor activator of nuclear factor κB expression in RAW264.7 cells. Crif1 was knocked out in RAW264.7 cells (RAW264.7-KO); B: Tartrate-resistant acid phosphatase (TRAP) staining of RAW264.7-KO and controls after 7 d of coculture with mouse bone marrow mesenchymal stem/stromal cells (BM-MSCs); C: Average number of TRAP-positive cells/well (arrow) from RAW264.7-KO and controls after 7 d of coculture with mouse BM-MSCs; D: Western blot analysis of Crif1 expression in BM-MSCs. Crif1 was knocked out in mouse BM-MSCs (BM-MSCs-KO), and BM-MSCs-KO and controls were irradiated with Co-60 at a single dose of 9 Gy; E: Real-time quantitative polymerase chain reaction analysis of receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) mRNA expression in BM-MSCs and BM-MSCs-KO. BM-MSCs and BM-MSCs-KO were cocultured with RAW264.7; F: RANKL/OPG ratio based on real-time quantitative polymerase chain reaction results; G: Enzyme linked immunosorbent assay analysis of RANKL protein levels in coculture supernatant medium; H: Enzyme linked immunosorbent assay analysis of OPG protein levels in coculture supernatant medium; I: RANKL/OPG ratio in coculture supernatant medium; J: TRAP staining of RAW264.7 after 7 d of coculture; K: Average number of TRAP-positive cells/well (arrow) from RAW264.7 in coculture. ^aP < 0.05 vs control (BM-MSCs), ^bP < 0.01 vs control (BM-MSCs); ^dP < 0.01 between 9 Gy-BM-MSCs and 9 Gy-BM-MSCs-KO, and the bars represent the mean ± standard deviation. BM-MSCs: Bone marrow mesenchymal stem/stromal cells; BM-MSCs-KO: Crif1 was knocked out from mouse BM-MSCs; RAW264.7-KO: Crif1 was knocked out from RAW264.7 cells; OPG: Osteoprotegerin; RANKL: Receptor activator of nuclear factor κB ligand.