Expression of Osterix in mechanical stress-induced osteogenic differentiation of periodontal ligament cells in vitro.
Osterix (Osx) is an osteoblast-specific transcription factor required for the differentiation of pre-osteoblasts into functional osteoblasts. This study sought to examine the changes of Osx expression in periodontal ligament cells (PDLC) subjected to mechanical force, and to investigate whether Osx is involved in the mechanical stress-induced differentiation of PDLC. Human PDLC were exposed to centrifugal force for 1-12 h. Real-time polymerase chain reaction (PCR), western blot, and immunofluorescence assays were used to examine the mRNA and protein expression of Osx and its subcellular localization. Furthermore, PDLC were transfected with the expression vector pcDNA3.1 flag-Osx and subjected to mechanical force for 6 h. The changes in alkaline phosphatase (ALP) activity and in the expression of core-binding factor alpha1 (Cbfa1), ALP, osteopontin, bone sialoprotein, osteocalcin, and collagen I were measured. After the application of mechanical force, Osx was upregulated in a time-dependent manner at both mRNA and protein levels, and Osx protein was translocated from the cytosol into the cell nuclei. Overexpression of Osx did not affect the expression of Cbfa1, but it significantly enhanced the ALP activity and the mRNA expression of all the aforementioned osteogenic marker genes, all of which increased further under mechanical stress. These results suggest that Osx might play an important role in the mechanical stress-induced osteogenic differentiation of PDLC and therefore be involved in alveolar bone remodeling during orthodontic therapy.
Zhao
Yanhong
Y
School of Stomatology, Shandong University, Jinan, Shandong, China.
Wang
Chunling
C
Li
Shu
S
Song
Hui
H
Wei
Fulan
F
Pan
Keqing
K
Zhu
Kun
K
Yang
Pishan
P
Tu
Qisheng
Q
Chen
Jake
J
D021581:Active Transport, Cell Nucleus; D000469:Alkaline Phosphatase / Q000096:biosynthesis; D015153:Blotting, Western; D016723:Bone Remodeling / Q000502:physiology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis; D003799:Dental Stress Analysis; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D006801:Humans; D058574:Integrin-Binding Sialoprotein; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D015675:Osteocalcin / Q000096:biosynthesis; D053495:Osteopontin / Q000096:biosynthesis; D010513:Periodontal Ligament / Q000166:cytology*; D016133:Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000096:biosynthesis; D000076182:Sp7 Transcription Factor; D013314:Stress, Mechanical; D014157:Transcription Factors / Q000096:biosynthesis*; D014162:Transfection; D015854:Up-Regulation
D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; C546871:IBSP protein, human; D058574:Integrin-Binding Sialoprotein; D012795:Sialoglycoproteins; D000076182:Sp7 Transcription Factor; C478163:SP7 protein, human; D014157:Transcription Factors; D015675:Osteocalcin; D053495:Osteopontin; D000469:Alkaline Phosphatase