The Effect Of Smurf1 In Regulating Ubiquitylation Of Bmp2 In Palatal Suture Of Mice During Mechanical Force-expansion

Part 1Osteoblast and osteoclast in palatal suture of mice during mechanical force-expansionObjective To detect the Osteoblast and osteoclast in the maxilla palatal suture of mice during the mechanical force-expansion period and discuss the significance of them in the suture remodeling after the expansion.Methods Six week-old male C57BL/6 mice were subjected to palatal suture expansion by opening loops with an initial force of 0.56 N for the periods of 1, 3, 5,7, 14 or 28 days. The sequence of histological changes in the midpalatal suture bone formation of animals was detected by hematoxylin eosin staining.Osteoblast were tested by alkaline phosphatase (ALP)staining and osteoclast were tested by tartrate-resistant acid phosphatase (TRAP) staining.Results Starting at day 1, cells expressing alkaline phosphatase was seen. New cartilage and bone formation was observed at the oral edges of the palatal bones at day 7,experimental 14d to 28d was gradually weakened disappeared positive;compared with the control group, osteoclast increased significantly along the inner lateral side of the cartilaginous tissue in expansion group at day 1,day 7 and 14 but at day 3 and day 28 they disappeared. Conclusions These findings demonstrate that expansion forces across the midpalatal suture promote bone resorption through activation of osteoclasts and bone formation and bone rebuild via increased proliferation and differentiation of periosteal cells.Part 2The effect of Smurf1 in regulating ubiquitylation of BMP2 in palatal suture of mice during mechanical force-expansionObjective To detect Smad ubiquitin regulatory factor1(Smurf1)effect the expression of BMP2 in the maxilla palatal suture of mice during the mechanical force-expansion period and discuss the significance of them in the suture remodeling after the expansion.Methods Six week-old male C57BL/6 mice were subjected to palatal suture expansion by opening loops with an initial force of 0.56 N for the periods of 1, 3, 5,7, 14 or 28 days. Through the paraffin sections by immunohistochemistry of Smurf1 and BMP2 to make organizational positioning.Expression of BMP2 and Smurf1 were tested by Westernblot. Study the expression of both the law and with no application of force of the control group to compare.Results Smurf1 localized in cartilage cells and new bone cell cytoplasm, BMP2 positioning in the mesenchymal cells and the cytoplasm of cartilage cells. The expression of BMP2 of expansion group was markedly higher than control group (P<0.05);Expansion group 3 day and 7 day was highest.However,the level of expansion group 14 day and 28 day is gradually declining but still higher than 1 day. The expression of Smurf1 was no distinct difference between expansion group 1 day and all control groups.The expression of Smurf1 of expansion group was gradually increased. Expansion group 3 day was higher than 1 day and 7day was significantly higher than 3 day but 14 days decreased (P<0.05). The 28day was the highest in expansion group. The control group in each group no significant difference (P>0.05).Conclusions Smurf1 ubiquitin activation inhibits BMP2 signaling pathway,making the expression of BMP2 decline, This process exists in the mice expansion process which ensuring maxilla palatal suture to restore the original structure after expansion and this physiological balance in the process of expansion is the key regulatory mechanism.