Major histocompatibility complex class II transactivator inhibits cysteine-rich 61 expression in osteoblastic cells and its implication in the pathogenesis of periapical lesions.
BACKGROUND
Osteoblastic expression of cysteine-rich 61 (Cyr61) correlates with the severity of periapical lesion-associated bone loss, but the regulatory mechanism of Cyr61 expression was not known.


METHODS
In the study we examined the effect of major histocompatibility complex class II transactivator (CIITA) on tumor necrosis factor (TNF)-alpha-induced Cyr61 synthesis in U2OS human osteoblastic cells by Western blot analysis. In a rat model of bacteria-induced apical periodontitis, we assessed the relation between osteoblastic expressions of CIITA/Cyr61 and disease progression by radiographic and immunohistochemistry studies.


RESULTS
We found that forced expression of CIITA suppressed Cyr61 synthesis in U2OS cells. In rat periapical lesions, osteoblastic CIITA decreased as the disease progressed, and expression of CIITA is negatively related to Cyr61 synthesis in osteoblasts.


CONCLUSIONS
Our data showed that CIITA is a repressor of Cyr61 synthesis in osteoblasts, and it might play a protective role in the pathogenesis of bone resorption in apical periodontitis, possibly through down-regulating the expression of Cyr61 in osteoblasts.
Lee
Yuan-Ling
YL
Graduate Institute of Clinical Dentistry, School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan.
Lin
Sze-Kwan
SK
Hong
Chi-Yuan
CY
Wang
Juo-Song
JS
Yang
Hsiang
H
Lai
Eddie Hsiang-Hua
EH
Chen
Mu-Hsiung
MH
Kok
Sang-Heng
SH
D016301:Alveolar Bone Loss / Q000473:pathology / Q000503:physiopathology; D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D055515:Cysteine-Rich Protein 61 / Q000037:antagonists & inhibitors* / Q000187:drug effects; D004195:Disease Models, Animal; D018450:Disease Progression; D004591:Electrophoresis, Polyacrylamide Gel; D005802:Genes, MHC Class II; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009687:Nuclear Proteins / Q000494:pharmacology*; D010006:Osteoblasts / Q000187:drug effects*; D010010:Osteoclasts / Q000473:pathology; D010485:Periapical Periodontitis / Q000382:microbiology / Q000503:physiopathology*; D019252:Radiography, Dental, Digital; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D015534:Trans-Activators / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D055515:Cysteine-Rich Protein 61; C083728:MHC class II transactivator protein; D009687:Nuclear Proteins; D015534:Trans-Activators; D014409:Tumor Necrosis Factor-alpha