Chen E, Piddington R, Decker S, Park J, Yuan Z A, Abrams W R, Rosenbloom J, Feldman G, Gibson C W
Department of Anatomy and Histology, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104.
Dev Dyn. 1994 Mar;199(3):189-98. doi: 10.1002/aja.1001990304.
The amelogenins are the predominant matrix proteins in developing enamel and are crucial for proper enamel mineralization. Transgenic mice were constructed in order to identify the segment of the amelogenin gene required for specific expression in enamel organ cells. A 3.5 kb fragment of the bovine X-chromosomal amelogenin gene that includes a TATA box, the transcription initiation site, and 32 bp of exon 1 was linked to the beta galactosidase gene and injected into fertilized mouse eggs. Newborn transgene positive mice expressed beta galactosidase activity in developing teeth treated with the chromogenic substrate Xgal. Foci of ameloblasts were positive in newborn mice; stain intensity and number of positive ameloblasts increased in 1-day and 2-day postnatal mice. Some of the adjacent stratum intermedium cells also were positive in the later stages. Targeting of the transgene to the enamel organ was specific; the only other cells observed to be positive were macrophages, which have endogenous beta galactosidase activity.
釉原蛋白是发育中的釉质中的主要基质蛋白，对釉质的正常矿化至关重要。构建转基因小鼠是为了确定釉原蛋白基因中在釉器细胞中特异性表达所需的片段。将包含TATA框、转录起始位点和外显子1的32 bp的牛X染色体釉原蛋白基因的3.5 kb片段与β-半乳糖苷酶基因相连，并注射到受精的小鼠卵中。新生的转基因阳性小鼠在用生色底物Xgal处理的发育牙齿中表达β-半乳糖苷酶活性。成釉细胞灶在新生小鼠中呈阳性；出生后1天和2天的小鼠中，阳性成釉细胞的染色强度和数量增加。在后期，一些相邻的中间层细胞也呈阳性。转基因靶向釉器是特异性的；观察到的唯一其他阳性细胞是巨噬细胞，其具有内源性β-半乳糖苷酶活性。
