ENAMEL MINERAL FORMATION DURING MURINE ODONTOGENESIS

说明(申请人提供)：釉原蛋白占形成牙釉质基质的有机成分的90%，这些蛋白在进化上高度保守。为了更好地了解釉原蛋白的功能，我们制作了一种定向干扰釉原蛋白基因座的小鼠模型，这是第一个描述牙齿细胞外基质蛋白的基因敲除小鼠。空白小鼠牙釉质发育不全，棱柱结构紊乱。釉原蛋白缺失的雌性小鼠可以与含有各种釉原蛋白表达载体的雄性小鼠交配，这种交配的雄性后代将只表达转基因，而不表达任何内源性釉原蛋白。该模型系统提供了一种方法来筛选釉原蛋白基因突变的重要性，以及从选择性剪接的mRNAs表达的釉原蛋白的功能。这项系统研究避免了Y染色体釉原蛋白表达的并发症，因为唯一的小鼠釉原蛋白基因位于X染色体上。其目的是(1)完成成釉蛋白缺失牙列的组成和物理特征的表征；(2)创造表达单个正常或突变的釉原蛋白蛋白的转基因小鼠，将它们与缺失的小鼠配对，并分析后代的牙齿；(3)评估LRAP在体内和体外的信号功能；以及(4)确定成熟成釉细胞、修复性牙本质和加速萌出过程中缺乏釉原蛋白的额外后果。

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