Spatiotemporal Expression of Ameloblastin Isoforms during Murine Tooth Development*
Spatiotemporal Expression of Ameloblastin Isoforms during Murine Tooth Development*
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DOI：
10.1074/jbc.m704731200
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发表时间：
2007-12
影响因子：
4.8
通讯作者：
R. Ravindranath;Asokan Devarajan;T. Uchida
中科院分区：
文献类型：
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作者：
R. Ravindranath;Asokan Devarajan;T. Uchida
成釉细胞合成并分泌釉基质蛋白（釉原蛋白、成釉蛋白和釉蛋白）。本研究使用成釉蛋白C-末端序列特异性抗体（Ct; GNKVHQPQVHNAWRF）检测了小鼠磨牙发育不同出生后（PN）天（0-9天）成釉蛋白在成釉细胞和釉质基质中的分布。在PN发育过程中，成釉细胞和釉质基质中发现了三种不同分子大小（37，55和66 kDa）的成釉蛋白。在成釉细胞中，这些组分的表达顺序不同。在第0天和第1天观察到37-kDa级分（甚至在蛋白酶、釉质溶素和激肽释放酶-4的mRNA出现之前），持续到第3天，此后未发现。其他亚型（55和66 kDa）明显出现在成釉细胞后1天，在第5天达到高峰，并保持此后。第3天，成釉细胞中出现串珠状Ct阳性颗粒。在细胞外基质中，在第0天和第1天检测到37-kDa（而不是66-或55-kDa）组分，并在整个PN天保持在基质中。较大的异构体（55和66 kDa）出现在釉质基质从第3天起。在第0-3天，但不晚于此，37-kDa亚型与釉原蛋白共定位在Tomes'过程和形成的釉质中，如激光扫描共聚焦显微镜所示。放射自显影证实积累的3 H-标记的釉原蛋白三酪氨酰基序肽在该地区的Tomes'的过程和形成釉质从第0天到第3天。这些观察结果表明，37 kDa的异构体与釉原蛋白在早期牙齿发育过程中相互作用。
Ameloblasts synthesize and secrete the enamel matrix proteins (amelogenin, ameloblastin, and enamelin). This investigation examined the profiles of ameloblastin in the ameloblasts and in the enamel matrix during different postnatal (PN) days (days 0-9) of development of mouse molar, using an antibody specific for C-terminal sequence of ameloblastin (Ct; GNKVHQPQVHNAWRF). Ameloblastin is found in three different molecular sizes (37, 55, and 66 kDa) in both ameloblasts and enamel matrix during PN development. In the ameloblasts, the sequence of expression of these fractions varied. The 37-kDa fraction was observed (even before the appearances of mRNA of the proteases, enamelysin and kallikrein-4) on days 0 and 1, persisted until day 3, and was not found thereafter. Other isoforms (55 and 66 kDa) distinctly appeared in ameloblasts after day 1, reached a peak on day 5, and remained thereafter. The Ct-positive granules appeared beaded in the ameloblasts on day 3. In the extracellular matrix, a 37-kDa (but not 66- or 55-kDa) fraction was detected on days 0 and 1 and remained in the matrix throughout the PN days. The larger isoforms (55 and 66 kDa) appeared in the enamel matrix from day 3 onward. On days 0-3, but not later, the 37-kDa isoform co-localizes with amelogenin in Tomes' process and formative enamel, as revealed by laser scan confocal microscopy. Autoradiography confirmed accumulation of 3H-labeled amelogenin trityrosyl motif peptide in the region of Tomes' process and formative enamel from day 0 to 3. These observations suggest that the 37-kDa isoform interacts with amelogenin during early tooth development.