ENAMEL MINERAL FORMATION DURING MURINE ODONTOGENESIS

描述（由申请人提供）：淀粉原蛋白占发育中的牙釉质基质有机成分的90%，这些蛋白在进化上是高度保守的。为了更好地了解淀粉原蛋白的功能，我们制作了一个有针对性地破坏淀粉原蛋白位点的小鼠模型，这是第一个被描述为牙齿细胞外基质蛋白的敲除小鼠。空白小鼠牙釉质发育不全，棱柱结构紊乱。无淀粉原蛋白的雌性小鼠可以与含有多种淀粉原蛋白表达载体的雄性小鼠交配，这种交配的雄性后代只表达转基因，不表达任何内源性淀粉原蛋白。该模型系统提供了一种方法来筛选淀粉原蛋白基因突变的意义，以及由可选剪接mrna表达的淀粉原蛋白的功能。这个系统的研究避免了y染色体淀粉原蛋白表达的复杂性，因为唯一的小鼠淀粉原蛋白基因在X染色体上。目的是：(1)完成淀粉原蛋白零列的组成和物理特性表征；(2)建立表达单一正常或突变的淀粉原蛋白的转基因小鼠，与空白小鼠交配，并分析后代的牙齿；(3)评价LRAP在体内和体外的信号功能；(4)确定成熟成釉细胞、修复性牙本质和加速出牙过程中缺乏成釉原蛋白的其他后果

DESCRIPTION (provided by applicant): The amelogenin proteins comprise 90% of the organic component of developing enamel matrix, and these proteins are highly conserved evolutionarily. In order to better understand amelogenin function, we have made a mouse model with a targeted disruption of the amelogenin locus, and this is the first knockout mouse described for a tooth extracellular matrix protein. Null mice have hypoplastic enamel with disorganized prism structure. The amelogenin null female mice can be mated with males that contain various amelogenin expression vectors, and male offspring of this mating will express only the transgene, without having any endogenous amelogenin expression. The model system provides a means to screen the significance of mutations in the amelogenin gene, and for function of amelogenins expressed from alternatively spliced mRNAs. This systematic study avoids the complication of Y-chromosomal amelogenin expression, as the sole murine amelogenin gene is on the X chromosome. The aims are (1) to complete the characterization of the amelogenin null dentition for composition and physical characteristics; (2) to create transgenic mice that express single normal or mutated amelogenin proteins, mate them with the null mice, and analyze teeth of offspring; (3) to evaluate LRAP for signal function in vivo and in vitro; and (4) to ascertain additional consequences of absence of amelogenin in maturative ameloblasts, in reparative dentin and during accelerated eruption