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Role of Cbfa1 in ameloblastin gene transcription. 总被引:8,自引:0,他引:8
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Two distinct osteoblast-specific cis-acting elements control expression of a mouse osteocalcin gene. 总被引:25,自引:0,他引:25
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Osteoblasts are cells of mesodermal origin that play a pivotal role during bone growth and mineralization. The mechanisms governing osteoblast-specific gene expression are still unknown. To understand these mechanisms, we analyzed the cis-acting elements of mouse osteocalcin gene 2 (mOG2), the best-characterized osteoblast-specific gene, by DNA transfection experiments in osteoblastic and nonosteoblastic cell lines and by DNA-binding assays. 5' deletion analysis of an mOG2 promoter-luciferase chimeric gene showed that a region located between -147 and -34 contained most if not all of the regulatory elements required for osteoblast-specific expression. Three different binding sites, called A, B, and C, for factors present in nuclear extracts of osteoblasts were identified in this short promoter by DNase I footprint assays. In gel retardation assays, the A element, located between bp -64 and -47, bound a factor present only in nuclear extracts of osteoblastic cell lines and nonmineralizing primary osteoblasts. The B element, located between bp -110 and -83, bound a ubiquitously expressed factor. The C element, located between bp -146 and -132, bound a factor present only in nuclear extracts of osteoblastic cell lines and nonmineralizing and mineralizing primary osteoblasts. When cloned upstream of a minimum osteocalcin promoter or a heterologous promoter, multimers of the A element strongly increased the activities of these promoters in osteoblastic cell lines at two different stages of differentiation but in no other cell line; we named this element osteocalcin-specific element 1 (OSE1). Multimers of the C element increased the activities of these promoters predominantly in a differentiated osteoblastic cell line; we named this element OSE2. This study demonstrates that two distinct cis-acting elements are responsible for osteoblast expression of mOG2 and provides for the first time a functional characterization of osteoblast-specific cis-acting elements. We speculate that these two elements may be important at several stages of osteoblast differentiation. 相似文献
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The osteoblast-specific transcription factor Cbfa1 contributes to the expression of osteoprotegerin, a potent inhibitor of osteoclast differentiation and function 总被引:17,自引:0,他引:17
Thirunavukkarasu K Halladay DL Miles RR Yang X Galvin RJ Chandrasekhar S Martin TJ Onyia JE 《The Journal of biological chemistry》2000,275(33):25163-25172
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MAPK pathways activate and phosphorylate the osteoblast-specific transcription factor, Cbfa1 总被引:19,自引:0,他引:19
Xiao G Jiang D Thomas P Benson MD Guan K Karsenty G Franceschi RT 《The Journal of biological chemistry》2000,275(6):4453-4459
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Regulation of osteocalcin gene expression by a novel Ku antigen transcription factor complex 总被引:10,自引:0,他引:10
Willis DM Loewy AP Charlton-Kachigian N Shao JS Ornitz DM Towler DA 《The Journal of biological chemistry》2002,277(40):37280-37291
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成骨分化相关基因骨钙素 (OC)等的启动子内均含有成骨特异性转录因子Cbfa1特异性作用元件 ,而骨形成蛋白 (bonemorphogeneticprotein ,BMP)的促成骨分化作用正是通过其首先引起Cbfa1的升高 ,而后Cbfa1激活这些基因的表达 ,最终出现成骨分化表型 .为解决BMP没有理想的活性测定方法的问题 ,在RT PCR结果证实BMP 2可促进NIH3T3和C2C12细胞Cbfa1表达后 ,构建了串联6个Cbfa1作用元件的小鼠OC部分启动子 (6OCP)控制萤光素酶 (luciferase)报告基因的真核表达质粒 ,以期来放大BMP诱导报告基因表达的作用效果 .即通过细胞转染、rhBMP 2刺激后检测萤光素酶活性变化 ,从而间接定量测定rhBMP 2的生物学活性 .结果表明 ,pcDNA3 6OCP Luc转染细胞后其报告基因的基础活性较pcDNA3 Luc大为降低 ;而且在一定剂量范围内 ,转染细胞的萤光素酶活性 (荧光值 )随rhBMP 2剂量增加而升高 ,并呈线性正相关 ,为建立BMP活性定量测定的方法打下基础 相似文献
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