Class II transactivator抑制人類造骨細胞Cyr61基因表現的機制
Class II Transactivator Suppresses Human Osteoblastic Cyr61 Gene Expression
Date Issued
2006
Date
2006
Author(s)
Wu, Chen-En
DOI
zh-TW
Abstract
AIMS: To evaluate the possible role of human Cyr61 in rheumatoid arthritis and the regulation mechanisms of Cyr61 gene expression by class II transactivator in human osteoblasts.
METHODS AND RESULTS: 1.） We assessed the transcriptional regulation of oncostatin-M （OSM）-induced Cyr61 gene expression in U2OS, a human osteosarcoma cell line with osteoblastic characters. Western blot revealed that OSM induced obvious Cyr61 synthesis and phsphorylation of cAMP responsive binding protein （CREB）. Luciferase assay showed elevated Cyr61 promoter activities following CREB over-expression. Electrophoretic mobility shift assay （EMSA） revealed significant CREB/DNA cross-talk after OSM stimulation. But, Dominant negative p300 showed no significant difference in inducing Cyr61 expression versus vector only in luciferase assay. 2.） We studied the regulation of class transcactivator （CIITA）. Western blot revealed that CIITA expression reduced Cyr61 expression and attenuated CREB activity. Luciferase assay showed CIITA regulates Cyr61 expressionin a dose-dependent manner CIITA and suppression on Cyr61 gene expression is CRE-dependent. CO-IP data indicated that CIITA reduced the binding between CREB / p300. 3.） In RA animal model we saw clearly ankylosis, bone resorption and granulation tissue infiltration. IHC data showed us Cyr61 expression in tissue-specific manner.
CONCLUSION: CREB phosphorylation and HAT activity of p300 was critical for Cyr61 gene expression. Class II transactivator suppressed Cyr61 transcription by sequester CREB and result in attenuating CREB / p300 binding. In vivo examination showed that Cyr61 expression in rheumatoid arthritis rat is cell and tissue specific.
INPACT OF THIS STUDY: This study provided the regulation mechanisms of Cyr61 gene expression in human osteoblasts and indicated a close relationship between Cyr61 expression and rheumatoid arthritis pathology.
Subjects
類風溼性關節炎
Cyr61
CIITA
CREB
p300
Rheumatoid arthritis
Type
other
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