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. cDNA reads reverse-transcribed from mRNA from cervical loop cells, secretory ameloblasts, and maturation ameloblasts dissected from 5 rats were generated by RNA-seq using an Illumina NextSeq 500 sequencer.