Expression And Role Of PLAP-1 On Development Of Mandibular First Molars In Mice

Background and ObjectivesPeriodontal ligament-associated protein-1(PLAP-1),also known as Asporin(ASPN),is a secretory extracellular matrix(ECM)protein that belongs to the small leucine-rich repeat proteoglycan(SLRP)family of proteins and contains a unique aspartic acid(D)repeat at its N-terminus.PLAP-1 mRNA was expressed in dental sac in the cap stage and bell stage of mouse tooth germ.The expression of PLAP-1 in periodontal ligament prevented the differentiation of periodontal stem cells,prevented the ossification of periodontal ligament,and maintained the normal physiological width of periodontal ligament.PLAP-1 is expressed in human predentin.PLAP-1 is expressed in bone tissue just above the tooth crown and is involved in the establishment of eruption channels.Tooth development is the result of mutual induction and interaction between mesenchymal cells and odontogenic epithelium.A variety of signaling molecules and proteins are involved in tooth development.This experiment aims to clarify the expression distribution of PLAP-1 in different stages of tooth development,study the role of Plap-1 gene in tooth development,and further explore the possible mechanism of tooth development.Materials and methodsIn mouse,mandibular first molar germs or teeth of embryonic(E)13.5,14.5,16.5 days and postnatal(P)0.5,5,10,15,20,25,30 days and 2 month were collected and stained with immunohistochemistry to observe the expression and distribution of PLAP-1 in different stages of tooth development.In both Plap-1 knockout mouse and wild-type homologous mouse,mandibular first molar germs or teeth of embryonic(E)13.5,14.5,16.5 days and postnatal(P)0.5,5,15,20,25,30 days and 2 month were collected and stained with stained with HE to observe the histological morphology.The periodontal ligament width of P30 days mandibular first molar teeth were measured.Results1.PLAP-1 was not expressed in the dental sac in the cap stage and bell stage,but was expressed in the tooth embryo crown square bone tissue,prophase dentin and odontoblast cell layer.2.PLAP-1 was slightly expressed in periodontal membrane at P10.5 days.With the development of teeth,PLAP-1 expression gradually increased.3.Compared with homologous wild mice,Plap-1 gene knockout mice showed no significant changes in the tissue structure and eruption time of mandibular first molar.4.The periodontal ligament width of mandibular first molar teeth in Plap-1 knockout mice was reduced compared with that in homologous wild-type mice.ConclusionPLAP-1 is expressed during tooth development in mice,PLAP-1 may be involved in tooth development,tooth eruption and tooth tissue formation.After Plap-1 gene knockout,there is no significant difference between the dental tissue and wild-type homologous mice,there may be a compensatory mechanism.PLAP-1 can inhibit the mineralization of periodontal tissue.