Biological Function Of Transcription Factor Sox9 During Mouse Molar Development

Objective:Odontogenesis involves the complex interactions between the dental epithelium and the mesenchyme.The mesenchymal cells are migrated from the neural crest cell of midbrain and afterbrain.The mesenchymal cells of odontogenes are derived from the cranial neural crest cell,and the transcription factor Sox9 plays an important role in migration and development of neural crest cell,so we speculate that Sox9 is involved in the process of mouse molar germ development.If Sox9 is involved in odontogenesis,what is the biological function of Sox9 during the mouse molar germs odontogenesis?This study aims to:To study the function of Sox9 during mouse tooth development:(1)To detect the expression pattern(temporal and spatial)of Sox9 during mouse molar development;(2)Using an organ culture model of the mouse molar germs in vitro to study the influence and biological function of Sox9 during mouse molar odontogenesis;(3)Organ culture of mDPCs in vitro was used for studying the influence of Sox9 to mDPCs,to further study the function of Sox9 during mouse molar germ odontogenesis.Material and methods:(1)IHC(immunohistochemistry)and ISH(in situ hybridization)was used for examining the different development stages of mouse molar germs,to observe and analyze the expression pattern of Sox9 during mouse incisor and molar development;(2)The organ culture model of the mouse molar germs in vitro and RNAi were used for inhibitting the expression of Sox9.HE staining was used for examining the morphological changes of mouse molar germs development;(3)To establish an organ culture model of mDPCs in vitro,inhibit the expression of Sox9 in mDPCs by RNAi.CCK8 staining were used for examining the proliferation ability of mDPCs.Results:(1)Using IHC and ISH to further clarify the translation expression of Sox9 during mouse molar development(E13.5～E18.5),in the early development of mouse molar germ,Sox9 protein was mainly detected in the mesenchymal cells labial side from E13.5 to E14.5,while detected in the dental papilla cells at E16.5 and in the dental pulp tissue at E18.5.Also,Sox9 strongly expressed in the dental epithelium of enamel organ in the early development of tooth germ;(2)The continuous frozen tissue slice of in vitro cultured mouse tooth germ which from the control group and experimental group(inhibit the expression of Sox9),culture for two days and make HE staining,find that the tooth germ of experimental group develop to late bud stage,while the control group develop to cup stage;(3)By detecting the organ culture model of mDPCs in vitro,which from the control group and experimental group(inhibit the expression of Sox9),find that inhibit the expression of Sox9,the proliferation ability of mDPCs has declined.Conclusions:(1)The expression pattern(temporal and spatial)of Sox9 during mouse molar development prompt that Sox9 may participate in mouse molar germ development;(2)In the organ culture model of the mouse molar germs in vitro,inhibit the expression.of Sox9 has delayed molar germ development,prompt that Sox9 plays an important role in the process of tooth germ development;(3)The organ culture model of mDPCs in vitro,inhibit the expression of Sox9 by RNAi,the mDPZCs’ proliferation ability has declined,prompt that Sox9 plays an important role in the proliferation of mDPCs.