Analyses with double knockouts of the <i>Bmpr1a</i> and <i>Bmpr1b</i> genes demonstrate that BMP signaling is involved in the formation of precerebellar mossy fiber nuclei derived from the rhombic lip

Bone morphogenetic proteins (BMPs) have been hypothesized to specify distinct dorsal neural fates. During neural development, BMPs are expressed in the roof plate and adjacent neuroepithelium. Because several hindbrain nuclei that form the proprioceptive/vestibular/auditory sensory network originate from the rhombic lip, near the roof plate, BMP signaling may regulate the development of these nuclei. To test this hypothesis genetically, we have examined the development of the hindbrain in BMP type I receptor knockout mice. Our results demonstrate that BMP signaling is involved in the formation of precerebellar mossy fiber nuclei, which give rise to cerebellar mossy fibers, but is not required for the development of the inferior olivary nucleus, which gives rise to cerebellar climbing fibers.已有假说提出，骨形态发生蛋白（Bone morphogenetic proteins, BMPs）可介导不同背侧神经命运的特化。在神经发育过程中，BMPs于顶板（roof plate）及邻近的神经上皮（neuroepithelium）中表达。由于构成本体感受/前庭/听觉感觉网络的多个后脑核起源于紧邻顶板的菱唇（rhombic lip），因此BMP信号通路可能调控此类后脑核的发育。为通过遗传学手段验证该假说，我们对BMP I型受体敲除小鼠（BMP type I receptor knockout mice）的后脑发育情况进行了分析。本研究结果显示，BMP信号通路参与介导小脑前苔藓纤维核（precerebellar mossy fiber nuclei）的形成，该核团可产生小脑苔藓纤维（cerebellar mossy fibers）；但对于下橄榄核（inferior olivary nucleus）的发育并非必需，该核团可产生小脑攀缘纤维（cerebellar climbing fibers）。