Table 1.
Primer sequences of Real-time RT-qPCR.
Fig 1.
Expression of sclerostin was different between the compression and tension sites during tooth movement.
(A) X-ray images showed the mesial movement of the first molars at 0 d, 7 d and 28 d. (C) IHC of sclerostin at the compression sites. Sclerostin maintained high expression at 1d, 3d, 5d and 7d and gradually diminished until 28 d. Alveolar bone (AB), PDL (periodontal ligament), and R (root). The blue arrow indicated the mesial side in control group and the direction of tooth movement in experiment groups. (D) IHC of sclerostin at the tension site. Sclerostin immediately decreased and was continually maintained at the low level during 28 days of tooth movement. AB (alveolar bone), PDL (periodontal ligament), R (root). (E) Semi-quantification of IHC of sclerostin at the compression sites. n = 3,**p<0.01 vs control, *** p<0.001 vs control. (F) Semi-quantification of IHC of sclerostin at the tension sites. n = 3, ***p<0.001 vs control, #p<0.05 vs compression site, ##p<0.01 vs compression site.
Fig 2.
The sclerostin expression of the MLO-Y4 cells was increased under hypoxic conditions, whereas it was not different under uniaxial compression and tension stress.
(A) The relative mRNA expression of SOST of the MLO-Y4 cells was decreased under compression stress. ***p<0.001 vs control. (B) The relative mRNA expression of SOST of the MLO-Y4 cells was decreased under compression stress. ***p<0.001 vs control. (C) The relative mRNA expression of the SOST mRNA of the MLO-Y4 cells was increased 48 h after being cultured under hypoxic conditions. ***p<0.001 vs control. (D) The release of sclerostin by the MLO-Y4 cells that was determined using ELISA increased 48 h after being cultured under hypoxic conditions. **p<0.01 vs control.
Fig 3.
The TRAP staining results showed that the osteoclastic activity was consistent with the sclerostin level at the compression sites during tooth movement.
(A) The TRAP-staining results in the compression sites at 0 d, 1 d, 3 d, 5 d, 7 d, 14 d, 21 d and 28 d during tooth movement. The TRAP-positive cells were identified as red multinuclear cells near the alveolar bone. Alveolar bone (AB), PDL (periodontal ligament), R (root). (B) The TRAP-staining results in the tension sites at 0 d, 1 d, 3 d, 5 d, 7 d, 14 d, 21 d and 28 d during tooth movement. The TRAP-positive cells were identified as red multinuclear cells near the alveolar bone. Alveolar bone (AB), PDL (periodontal ligament), R (root). (C) The quantification of TRAP-positive cells per bone surface (mm-1) at the compression sites. The number of active osteoclasts increased to the apex in the first three days and gradually decreased with time. *p<0.05 vs 0 d, ***p<0.001 vs 0 d. (D) The quantification of TRAP-positive cells per bone surface (mm-1) at the tension sites. The number of active osteoclasts increased to the apex in the first three days and gradually decreased with time.
Fig 4.
Osteoclastic activity was decreased in the SOST deficient mice compared to the WT mice during tooth movement.
(A) TRAP staining at the compression sites in the WT and SOST KO mice at 0 d, 2 d and 4 d. (B) TRAP staining at the compression sites in the WT and SOST KO mice at 6 d, 8 d and 10 d. (C) Quantification of the osteoclasts number per bone surface (mm-1) at the compression site of mice tooth movement. The osteoclast number/bone perimeter increased to the apex at day 4 and gradually decreased through day 10 in the SOST KO mice and WT mice. The number of osteoclasts was significantly lower in the SOST KO mice than in the WT mice at 4d, 6d, and 8d. *p<0.05 vs WT. ***p<0.001 vs WT.
Fig 5.
Sclerostin enhanced RANKL expression and osteoclastic inducible ability of osteocytes.
(A) Relative mRNA expression of RANKL in the MLO-Y4 cells under 0 ng/ml, 10 ng/ml, 30 ng/ml, 50 ng/ml and 100 ng/ml rhSCL interference. The expression of RANKL was significantly increased with 30 ng/ml, 50 ng/ml and 100 ng/ml. *p<0.05 vs 0 ng/ml. **p<0.01 vs 0 ng/ml. (B) The relative mRNA expression of OPG in the MLO-Y4 cells under rhSCL interference. No significant change in the OPG level. (C) The ratio of RANKL/OPG was significantly increased under 50 ng/ml and 100 ng/ml rhSCL interference. **p<0.01 vs 0 ng/ml. (D) The release of RANKL by MLO-Y4 was determined by ELISA under rhSCL interference. **p<0.01 vs 0 ng/ml. (E) The TRAP staining of the co-culture of the MLO-Y4 and RAW264.7 cells with or without rhSCL interference. (F) There was a significantly greater number of TRAP-positive cells in the rhSCL group than in the control group. ***p<0.001.