Gene expression fingerprinting of ameloblasts shows changes in the endocytosis/cytoskeleton interface across stages.

We used RNA-seq to identify differentially expressed genes across ameloblast stages in rats. We found expression patterns of enamel matrix proteins, ion channels and transporters, and endocytosis regulators such as clathrin to match those found in previous experimental studies on ameloblasts. We hypothesized that ameloblasts change their endocytotic pathways as they progress from stage and stage, and we sought to identify novel patterns in expression of genes at the endocytosis/cytoskeleton interface. We found that maturation ameloblasts preferentially express synaptojanin 1 and intersectin 2 and secretory ameloblasts preferentially express Numb protein and amphiphysin. We also uncovered differential alternative splicing of ECI genes across ameloblast populations. In pointing to endocytotic genes hitherto unexplored in ameloblasts that also regulate cell morphology, this bioinformatics study suggests a mechanism by which cervical loop, secretory, and maturation ameloblasts switch modes of endocytosis in order to express genes that better suit the distinct morphology of each cell stage.本研究采用RNA测序（RNA-seq）技术，鉴定大鼠体内不同发育阶段成釉细胞（ameloblast）的差异表达基因。我们发现，牙釉质基质蛋白、离子通道、转运蛋白以及网格蛋白（clathrin）等内吞调控因子的表达模式，与此前针对成釉细胞开展的实验研究结果相符。我们推测，成釉细胞在不同发育阶段转换过程中，其体内的内吞通路会发生改变，本研究旨在鉴定内吞/细胞骨架（cytoskeleton）界面相关基因的新型表达模式。结果显示，成熟成釉细胞优先表达突触多磷酸肌醇磷酸酶1（synaptojanin 1）与衔接蛋白2（intersectin 2），而分泌型成釉细胞则优先表达Numb蛋白（Numb protein）及双载蛋白（amphiphysin）。此外，我们还发现不同成釉细胞群体中ECI基因（ECI genes）存在差异性可变剪接。本项生物信息学研究聚焦于此前在成釉细胞中尚未被探索的、同时调控细胞形态的内吞相关基因，提出了一套潜在机制：颈环（cervical loop）细胞、分泌型成釉细胞与成熟成釉细胞可通过切换内吞模式，以表达更适配各细胞阶段独特形态的基因。