Tooth cusp is a crucial structure, since the shape of the molar tooth is determined by number, shape, and size of the cusp. Bone morphogenetic protein (Bmp) signaling is known to play a critical role in tooth development, including in initiation. However, it remains unclear whether Bmp signaling is also involved in cusp formation. To address this question, we examined cusp in two different transgenic mouse lines: mice with overexpression of Bmp4 (K14-Bmp4), and those with Bmp inhibitor, Noggin, (K14-Noggin) under keratin14 (K14) promoter. K14-Noggin mice demonstrated extra cusps, whereas reduced number of cusps was observed in K14-Bmp4 mice. To further understand how Bmps are expressed during cusp formation, we performed whole-mount in situ hybridisation analysis of three major Bmps (Bmp2, Bmp4, and Bmp7) in murine maxillary and mandibular molars from E14.5 to P3. The linear expressions of Bmp2 and Bmp4 were observed in both maxillary and mandibular molars at E14.5. The expression patterns of Bmp2 and Bmp4 became significantly different between the maxillary and mandibular molars at E16.5. At P3, all Bmps were expressed in all the cusp regions of the maxillary molar; however, the patterns differed. All Bmps thus exhibited dynamic temporo-spatial expression during the cusp formation. It could therefore be inferred that Bmp signaling is involved in regulating cusp formation.

牙尖是至关重要的结构，因为磨牙的形状由牙尖的数量，形状和大小决定。众所周知，骨形态发生蛋白（Bmp）信号在牙齿发育（包括引发）中起关键作用。但是，尚不清楚Bmp信号传导是否也参与尖瓣形成。为了解决这个问题，我们检查了两种不同的转基因小鼠品系的尖点：Bmp4（K14-Bmp4）过表达的小鼠和角蛋白14（K14）启动子下具有Bmp抑制剂Noggin（K14-Noggin）的小鼠。K14-Noggin小鼠表现出额外的风口，而在K14-Bmp4中观察到风口数减少老鼠。为了进一步了解Bmp在尖瓣形成过程中如何表达，我们对从E14.5到P3的鼠上颌和下颌磨牙中的三个主要Bmp（Bmp2，Bmp4和Bmp7）进行了全安装原位杂交分析。在E14.5，在上颌和下颌磨牙中都观察到了Bmp2和Bmp4的线性表达。Bmp2和Bmp4的表达模式在上颌和下颌磨牙之间在E16.5处变得明显不同。在P3时，所有Bmps都在上颌磨牙的所有尖端区域表达。但是，模式有所不同。所有因此，Bmp在尖端形成过程中表现出动态的时空表达。因此可以推断，Bmp信号传导参与调节尖瓣的形成。