title: Role of Protein Phosphatase 1 in Angiogenesis and Odontoblastic Differentiation of Human Dental Pulp Cells.
abstract: BACKGROUND
  The aims of this study were to examine the immunolocalization of protein phosphatase 1 (PP1) in developing mouse pulp tissue and to explore the role of PP1 in odontoblastic differentiation and in vitro angiogenesis in human dental pulp cells (HDPCs).
  
  
  METHODS
  Immunolocalization of PP1 was assessed in developing mouse pulp tissue. Odontogenic differentiation was examined by alkaline phosphatase activity, alizarin red staining, and reverse transcriptase polymerase chain reaction. Angiogenesis was evaluated by endothelial cell migration and capillary tube formation. Signaling pathways were analyzed by Western blotting and confocal immunofluorescence.
  
  
  RESULTS
  PP1 expression was detected in preodontoblasts, odontoblasts, dental pulp cells, and endothelial cells within pulp tissue during the crown formed, root formation, and root completion stages. PP1 messenger RNA (mRNA) and protein levels were up-regulated at the late mineralization stage during odontogenic differentiation of HDPCs. The PP1 activator C2 ceramide increased alkaline phosphatase activity, mineralized nodule formation, and mRNA expression of dentin matrix protein 1 and dentin sialophosphoprotein. In contrast, knockdown by PP1 small interfering RNA inhibited odontoblastic differentiation. Moreover, PP1 activator up-regulated mRNA expression of angiogenic genes in HDPCs and increased the migration and capillary tube formation of endothelial cells, whereas PP1 small interfering RNA showed opposite effects. C2 ceramide increased levels of bone morphogenetic protein 2, phosphorylation of Smad 1/5/8, and mRNA expression of runt-related transcription factor 2 and osterix.
  
  
  CONCLUSIONS
  This study provides the first evidence that PP1 might be a potent regulator of developing pulp tissue in vivo and odontoblastic differentiation and angiogenesis in HDPCs in vitro and may have clinical implications for pulp/dentin regeneration or reparative dentinogenesis.
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry and Research Center for Tooth and Periodontal Regeneration, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Ji-Youn
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Duk-Su
authors.initials: DS
authors.lastname: Kim
authors.affiliation: Department of Oral Medicine, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Q-Schick
authors.initials: QS
authors.lastname: Auh
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Jin-Kyu
authors.initials: JK
authors.lastname: Yi
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry and Research Center for Tooth and Periodontal Regeneration, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Sung Ung
authors.initials: SU
authors.lastname: Moon
authors.affiliation: Department of Oral and Maxillofacial Pathology, School of Dentistry and Research Center for Tooth and Periodontal Regeneration, Kyung Hee University, Seoul, Republic of Korea. Electronic address: eckim@khu.ac.kr.
authors.forename: Eun-Cheol
authors.initials: EC
authors.lastname: Kim
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D002465:Cell Movement; D002478:Cells, Cultured; D003782:Dental Pulp / Q000098:blood supply / Q000166:cytology*; D020868:Gene Silencing; D006801:Humans; D051379:Mice; D018919:Neovascularization, Physiologic / Q000502:physiology*; D054645:Protein Phosphatase 1 / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D012333:RNA, Messenger; D054645:Protein Phosphatase 1
keywords: Angiogenesis; differentiation; human dental pulp cells; protein phosphatase 1; pulp tissue