Synthesis, secretion, degradation, and fate of ameloblastin during the matrix formation stage of the rat incisor as shown by immunocytochemistry and immunochemistry using region-specific antibodies
Synthesis, secretion, degradation, and fate of ameloblastin during the matrix formation stage of the rat incisor as shown by immunocytochemistry and immunochemistry using region-specific antibodies
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DOI：
10.1177/002215549704501002
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发表时间：
1997-10-01
影响因子：
3.2
通讯作者：
Takahashi, O
中科院分区：
文献类型：
--
作者：
Uchida, T;Murakami, C;Takahashi, O
成釉蛋白是新近克隆的一种牙齿特异性釉基质蛋白，含有422个氨基酸残基。我们研究了这种蛋白质的表达在大鼠切牙基质形成阶段的免疫化学和免疫化学，使用抗合成肽抗体，识别残基27-47（Nt），98-107（M-1），224-232（M-2），386-399（M-3），和406-419（Ct）的成釉蛋白。免疫组织化学制剂使用抗体Nt和M-1染色的高尔基体和分泌颗粒的分泌成釉细胞和整个厚度的釉基质。只有M-1强烈染色的周边区域的釉杆。在65、55和22 kD附近观察到免疫染色蛋白条带。免疫组织化学制剂使用抗体M-2和Ct染色的高尔基体和分泌颗粒的成釉细胞和未成熟的釉质附近的分泌位点，但不更深的釉质层。用M-2和Ct进行免疫染色，分别在65和40-56 kD附近和65、55、48、36和25 kD附近显示蛋白条带。M-3染色高尔基体的顺式侧，但不染色釉基质。该抗体识别55 kD附近的蛋白质条带，但没有更大的。布雷菲德菌素A治疗后，免疫反应的55 kD蛋白带加强，和扩张池的分泌成釉细胞的rER含有免疫反应物质，无论使用的抗体。这些数据表明，成釉蛋白是作为一个55-kD的核心蛋白合成，然后进行后修饰的O-连接的寡糖，成为65-kD的分泌形式。初始裂解的65 kD蛋白产生N-末端多肽，其中一些集中在棱镜鞘，和C-末端多肽，这是迅速降解和失去的釉基质分泌后不久。
Rat ameloblastin is a recently cloned tooth-specific enamel matrix protein containing 422 amino acid residues. We investigated the expression of this protein during the matrix formation stage of the rat incisor immunohistochemically and immunochemically, using anti-synthetic peptide antibodies that recognize residues 27-47 (Nt), 98-107 (M-1), 224-232 (M-2), 386-399 (M-3), and 406-419 (Ct) of ameloblastin. Immunohistochemical preparations using antibodies Nt and M-1 stained the Golgi apparatus and secretory granules of the secretory ameloblast and the entire thickness of the enamel matrix. Only M-1 intensely stained the peripheral region of the enamel rods. Immunostained protein bands were observed near 65, 55, and below 22 kD. Immunohistochemical preparations using antibodies M-2 and Ct stained the Golgi apparatus and secretory granules of the ameloblast and the immature enamel adjacent to the secretion sites, but not deeper enamel layers. Immunostaining using M-2 and Ct revealed protein bands near 65 and 40-56 kD, and 65, 55, 48, 36, and 25 kD, respectively. M-3 stained the cis side of the Golgi apparatus but not the enamel matrix. This antibody recognized a protein band near 55 kD, but none larger. After brefeldin A treatment, immunoreaction of the 55-kD protein band intensified, and dilated cisternae of rER of the secretory ameloblast contained immunoreactive material irrespective of the antibodies used. These data indicate that ameloblastin is synthesized as a 55-kD core protein and then is post-translationally modified with O-linked oligosaccharides to become the 65-kD secretory form. Initial cleavages of the 65-kD protein generate N-terminal polypeptides, some of which concentrate in the prism sheath, and C-terminal polypeptides, which are rapidly degraded and lost from the enamel matrix soon after secretion.