Amelotin Gene Structure and Expression during Enamel Formation in the Opossum Monodelphis domestica

摘要: Amelotin (AMTN) is an ameloblast-secreted protein that belongs to the secretory calcium-binding phosphoprotein family, which also includes enamel matrix proteins amelogenin, ameloblastin and enamelin. Although AMTN supposed play important role in formation, data were long limited rodents, it expressed during maturation stage. Recent comparative studies sauropsids amphibians revealed (i) was earlier, i.e. as soon ameloblasts are depositing matrix, (ii) structure different, a change mostly resulted from intraexonic splicing large exon 8 of ancestral mammal. The present study performed know whether differences expression rodents compared non-mammalian tetrapods dated back early mammal or acquired later mammalian evolution. We sequenced, assembled screened jaw transcriptome neonate opossum Monodelphis domestica, marsupial. found two transcripts. Variant 1, representing 70.8% transcripts, displayed known whereas variant 2 (29.2%) exhibited nonmammalian tetrapod structure. Then, we studied amelogenesis specimen. obtained similar those reported rodents. These findings indicate more than 180 million years ago, before divergence marsupials placentals, changes occurred function spatiotemporal delayed stage gave rise isoform encoded by 1 lacking RGD motif. 2, housing RGD, initially conserved, demonstrated here marsupial, then secondarily lost placental lineages. bring new elements towards our understanding non-prismatic prismatic transition at onset mammals.