Studies on animal models with mutations in ameloblastin gene have suggested that the extracellular matrix protein ameloblastin (AMBN) plays important roles in controlling cell-matrix adhesion and ameloblast polarization during amelogenesis. In order to examine the function of AMBN in cell polarization and morphology, we developed an in vitro 3D cell culture model to examine the effect of AMBN and amelogenin (AMEL) addition on ameloblast cell lines. We further used high resolution confocal microscopy to detect expression of polarization markers in response to AMBN addition. Addition of AMBN to the 3D culture matrix resulted in the clustering and elongation (higher aspect ratio) of ALC in a dose dependent manner. The molar concentration of AMEL required to exact this response from ALC was 2.75- times greater than that of AMBN. This polarization effect of ameloblastin was attributable directly to an evolutionary conserved domain within its exon 5-encoded region. The lack of exon 6-encoded region also influenced AMBN-cell interactions but to a lesser extent. The clusters formed with AMBN were polarized with expression of E-cadherin, Par3 and Cldn1 assembly at the nascent cell-cell junctions. The elongation effect was specific to epithelial cells of ameloblastic lineage ALC and LS8 cells. Our data suggest that AMBN may play critical signaling roles in the initiation of cell polarity by acting as a communicator between cell-cell and cell-matrix interactions. Our investigation has important implications for understanding the function of ameloblastin in enamel-cell matrix adhesion and the outcomes may contribute to efforts to develop strategies for enamel tissue regeneration.

成釉细胞基因突变动物模型研究基因表明，细胞外基质蛋白成釉蛋白 (AMBN) 在成釉过程中控制细胞-基质粘附和成釉细胞极化方面起着重要作用。为了检查 AMBN 在细胞极化和形态学中的功能，我们开发了一个体外 3D 细胞培养模型来检查 AMBN 和牙釉蛋白 (AMEL) 添加对成釉细胞系的影响。我们进一步使用高分辨率共聚焦显微镜来检测响应 AMBN 添加的偏振标记的表达。将 AMBN 添加到 3D 培养基质导致 ALC 以剂量依赖的方式聚集和伸长（更高的纵横比）。从 ALC 获得这种反应所需的 AMEL 摩尔浓度是 AMBN 的 2.75 倍。成釉细胞的这种极化效应直接归因于其外显子 5 编码区域内的进化保守域。外显子 6 编码区域的缺失也影响了 AMBN 细胞相互作用，但影响较小。用 AMBN 形成的簇在新生细胞-细胞连接处随着 E-钙粘蛋白、Par3 和 Cldn1 组装的表达而极化。伸长效应对成釉细胞谱系 ALC 和 LS8 细胞的上皮细胞具有特异性。我们的数据表明，AMBN 可能通过充当细胞-细胞和细胞-基质相互作用之间的沟通者，在细胞极性的启动中发挥关键的信号转导作用。我们的研究对于理解成釉蛋白在釉质细胞基质粘附中的功能具有重要意义，其结果可能有助于制定釉质组织再生策略。