Coffin–Lowry–Syndrome (CLS) is a X-linked mental retardation characterized by skeletal dysplasia and premature tooth loss. We and others have previously demonstrated that the ribosomal S6 kinase RSK2, mutated in CLS, is essential for bone and cementum formation; however, it remains to be established whether RSK2 plays also a role in mechanically induced bone remodeling during orthodontic tooth movement (OTM). We, therefore, performed OTM in wild-type (WT) mice and Rsk2-deficient mice using Nitinol tension springs that were fixed between the upper left molars and the incisors. The untreated contralateral molars served as internal controls. After 12 days of OTM, the jaws were removed and examined by micro-computed tomography (µCT), decalcified histology, and immunohistochemistry. Our analysis of the untreated teeth confirmed that the periodontal phenotype of Rsk2-deficient mice is characterized by alveolar bone loss and hypoplasia of root cementum. Quantification of OTM using µCT revealed that OTM was more than two-fold faster in Rsk2-deficient mice as compared to WT. We also observed that OTM caused alveolar bone loss and root resorptions in WT and Rsk2-deficient mice. However, quantification of these orthodontic side effects revealed no differences between WT and Rsk2-deficient mice. Taken together, Rsk2 loss-of-function accelerates OTM in mice without causing more side effects.

棺材-低位综合征（CLS）是一种X连锁的智力低下，其特征是骨骼发育不良和牙齿过早脱落。我们和其他人先前已经证明，CLS中突变的核糖体S6激酶RSK2对于骨骼和牙骨质的形成至关重要。但是，在正畸牙齿移动（OTM）期间，RSK2是否在机械诱导的骨骼重塑中也起着作用尚待确定。因此，我们使用固定在左上磨牙和门牙之间的镍钛诺拉伸弹簧在野生型（WT）小鼠和Rsk2缺陷型小鼠中进行OTM。未经处理的对侧磨牙可作为内部对照。OTM处理12天后，取下颌并通过微计算机断层扫描（µCT），脱钙的组织学和免疫组织化学检查。Rsk2缺陷型小鼠的特征是牙槽骨丢失和牙骨质发育不全。使用µCT对OTM进行定量显示，与WT相比，Rsk2缺陷型小鼠的OTM速度快两倍以上。我们还观察到OTM引起WT和Rsk2缺陷型小鼠的牙槽骨丢失和根吸收。但是，这些正畸副作用的定量显示，WT和Rsk2缺陷型小鼠之间没有差异。两者合计，Rsk2功能丧失加速了小鼠的OTM，而没有引起更多的副作用。