Isolation and Functional Analysis of an Immortalized Murine Cementocyte Cell Line, IDG-CM6.
The dental cementum covering the tooth root is similar to bone in several respects but remains poorly understood in terms of development and differentiation of cementoblasts, as well as the potential function(s) of cementocytes residing in the cellular cementum. It is not known if the cementocyte is a dynamic actor in cementum metabolism, comparable to the osteocyte in the bone. Cementocytes exhibit irregular spacing and lacunar shape, with fewer canalicular connections compared with osteocytes. Immunohistochemistry and quantitative PCR (qPCR) revealed that the in vivo expression profile of cementocytes paralleled that of osteocytes, including expression of dentin matrix protein 1 (Dmp1/DMP1), Sost/sclerostin, E11/gp38/podoplanin, Tnfrsf11b (osteoprotegerin [OPG]), and Tnfsf11 (receptor activator of NF-κB ligand [RANKL]). We used the Immortomouse(+/-); Dmp1-GFP(+/-) mice to isolate cementocytes as Dmp1-expressing cells followed by immortalization using the interferon (IFN)-γ-inducible promoter driving expression of a thermolabile large T antigen to create the first immortalized line of cementocytes, IDG-CM6. This cell line reproduced the expression profile of cementocytes observed in vivo, including alkaline phosphatase activity and mineralization. IDG-CM6 cells expressed higher levels of Tnfrsf11b and lower levels of Tnfsf11 compared with IDG-SW3 osteocytes, and under fluid flow shear stress, IDG-CM6 cells significantly increased OPG while decreasing RANKL, leading to a significantly increased OPG/RANKL ratio, which would inhibit osteoclast activation. These studies indicate similarities yet potentially important differences in the function of cementocytes compared with osteocytes and support cementocytes as mechanically responsive cells.
Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.|Department of Orthodontics, Shanghai Key Laboratory of Stomatology, Shanghai No. 9 Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
Ning
N
Zhao
Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.|Department of Prosthodontics and Periodontics, Division of Periodontics, School of Dentistry at Piracicaba, Piracicaba, Sao Paulo, Brazil.
Francisco H
FH
Nociti
Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.|Department of Orthodontics, State Key Laboratory of Oral Diseases, West China College of Stomatology, Sichuan University, Chengdu, China.
Peipei
P
Duan
Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.|Bone Cell Biology Group, Centre for Orthopaedic & Trauma Research, University of Adelaide, Adelaide, Australia.
Matthew
M
Prideaux
Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.
Hong
H
Zhao
Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.|Division of Biosciences, College of Dentistry, The Ohio State University, Columbus, OH, USA.
Brian L
BL
Foster
Laboratory of Oral Connective Tissue Biology, National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), National Institutes of Health (NIH), Bethesda, MD, USA.
Martha J
MJ
Somerman
Department of Oral and Craniofacial Sciences, School of Dentistry, University of Missouri-Kansas City, Kansas City, MO, USA.
Lynda F
LF
Bonewald
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002461:Cell Line, Transformed; D003739:Dental Cementum / Q000166:cytology* / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D010011:Osteocytes / Q000166:cytology* / Q000378:metabolism; D053244:Osteoprotegerin / Q000235:genetics / Q000378:metabolism; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism; D000098853:Podoplanin
D048868:Adaptor Proteins, Signal Transducing; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D053244:Osteoprotegerin; D053245:RANK Ligand; C513308:Dmp1 protein, mouse; C490441:Pdpn protein, mouse; D000098853:Podoplanin; C486030:Sost protein, mouse; C506031:Tnfrsf11b protein, mouse; C505689:Tnfsf11 protein, mouse
CEMENTOCYTES; DENTAL CEMENTUM; IDG-CM6; OPG; RANKL; SCLEROSTIN