title: Ameloblastin regulates cell attachment and proliferation through RhoA and p27.
abstract: The matrix adhesion protein ameloblastin (AMBN) is one of the unique components of the mineralizing matrix of bones and teeth. Here we focused on two types of cells expressing AMBN - mouse dental follicle cells (mDF) and mouse periodontal ligament cells (mPDL) - to decipher AMBN function in developing dental, periodontal, and bone tissues. To test AMBN function, cell culture dishes of mDF and mPDL were exposed to either full-length or C-terminal (amino acids 137-407) recombinant Ambn protein. Alternatively, cells were subjected to transient transfection using an Ambn-small hairpin (sh) RNA vector. Our cell culture studies documented that dishes coated with full-length AMBN promoted the attachment of mPDL and mDF cells as early as 1 h after seeding. In order to identify potential intermediaries that might aid the effect of AMBN on adhesion, RhoA expression levels in AMBN-coated and uncoated control dishes were assessed. These studies indicated that AMBN induced RhoA expression 4 h after seeding, especially in mPDL cells. After 4 h of culture, the cell cycle inhibitor p27 was also up-regulated. In addition, exogenous AMBN and its C-terminal fragment reduced the proliferation of mDF and mPDL. Finally, transient transfection of mDF and mPDL cells with the Ambn-shRNA vector resulted in the down-regulation of p27 in mPDL cells. Together, these data indicate that AMBN affects cell adhesion via RhoA and cell cycle progression through p27.
authors.affiliation: Brodie Laboratory for Craniofacial Genetics, University of Illinois at Chicago, Chicago, IL 60612, USA.
authors.forename: Youbin
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.forename: Xuanyu
authors.initials: X
authors.lastname: Lu
authors.forename: Phimon
authors.initials: P
authors.lastname: Atsawasuwan
authors.forename: Xianghong
authors.initials: X
authors.lastname: Luan
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D021982:Cell-Matrix Junctions / Q000187:drug effects; D002478:Cells, Cultured; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D003746:Dental Enamel Proteins / Q000037:antagonists & inhibitors / Q000494:pharmacology / Q000502:physiology*; D003795:Dental Sac / Q000166:cytology / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000502:physiology; D051379:Mice; D010513:Periodontal Ligament / Q000166:cytology / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*
chemical_list: C490890:Ambn protein, mouse; D003746:Dental Enamel Proteins; D016326:Extracellular Matrix Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D020742:rhoA GTP-Binding Protein