Postproliferative transcription of the rat osteocalcin gene is reflected by vitamin D-responsive developmental modifications in protein-DNA interactions at basal and enhancer promoter elements.
Postproliferative transcription of the rat osteocalcin gene is reflected by vitamin D-responsive developmental modifications in protein-DNA interactions at basal and enhancer promoter elements.
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大鼠骨钙素基因的增殖后转录通过基础启动子和增强子启动子元件处蛋白质-DNA相互作用的维生素D响应性发育修饰来反映。
DOI：
10.1073/pnas.90.4.1503
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发表时间：
1993
影响因子：
11.1
通讯作者：
Lian,JB
中科院分区：
文献类型：
--
作者：
Owen,TA;Bortell,R;Shalhoub,V;Heinrichs,A;Stein,JL;Stein,GS;Lian,JB
在骨钙素（OC）基因启动子中，独立的正调控元件和负调控元件以及具有连续[TATA/糖皮质激素应答元件（GRE）]或重叠[TATA/GRE、维生素D应答增强子元件（VDRE）/AP-1和OC box/AP-1]结构域的其它元件是蛋白质-DNA相互作用的修饰位点。在本研究中，我们研究了从胎鼠颅骨细胞中提取的核蛋白，这些细胞经历了骨细胞分化的发育序列。我们的研究结果表明，蛋白质-DNA相互作用的修改，涉及到成骨细胞的发育阶段，并支持OC基因转录的发育调控。OC基因的基础表达与OC盒、VDRE和TATA/GRE盒的序列特异性蛋白质-DNA相互作用相关。在增殖成骨细胞中观察到明显的差异，其中OC基因不转录相比，增殖后，分化的成骨细胞转录的OC基因。此外，反映激素控制的蛋白质-DNA复合物也受到发育调节，介导OC基因的转录活性和抑制状态。例如，在增殖的成骨细胞中，形成了维生素D受体-抗体敏感复合物，该复合物不同于OC基因转录时由维生素D增殖后诱导的DNA结合复合物。类固醇激素结合结构域和重叠的AP-1位点在VDRE的突变分析支持Fos-Jun异二聚体和维生素D受体的互斥占用。在VDRE的这种蛋白质-DNA相互作用与维生素D介导的转录增强在表达高水平Fos和Jun的增殖成骨细胞中的能力的抑制是一致的。
In the osteocalcin (OC) gene promoter, both independent positive and negative regulatory elements, as well as others with contiguous [TATA/glucocorticoid-responsive elements (GRE)] or overlapping [TATA/GRE, vitamin D-responsive enhancer elements (VDRE)/AP-1, and OC box/AP-1] domains, are sites for modifications in protein-DNA interactions. In the present studies, we have examined nuclear protein extracts from fetal rat calvarial cells that undergo a developmental sequence of bone cell differentiation. Our results demonstrate modifications in protein-DNA interactions that relate to the developmental stages of the osteoblast and support developmental regulation of OC gene transcription. Basal expression of the OC gene is associated with sequence-specific protein-DNA interactions at the OC box, VDRE, and TATA/GRE box. Distinct differences are observed in proliferating osteoblasts, where the OC gene is not transcribed compared to postproliferative, differentiated osteoblasts that transcribe the OC gene. Furthermore, the protein-DNA complexes that reflect hormonal control are also developmentally regulated, mediating both the transcriptionally active and repressed states of the OC gene. For example, in proliferating osteoblasts, a vitamin D receptor-antibody-sensitive complex is formed that is different from the DNA binding complex induced by vitamin D postproliferatively when the OC gene is transcribed. Mutational analysis of the steroid hormone binding domain and the overlapping AP-1 site at the VDRE supports mutually exclusive occupancy by Fos-Jun heterodimers and vitamin D receptor. Such protein-DNA interactions at the VDRE are consistent with repression of competency for vitamin D-mediated transcriptional enhancement in proliferating osteoblasts expressing high levels of Fos and Jun.