STRUCTURE OF THE RAT OSTEOCALCIN GENE AND REGULATION OF VITAMIN-D-DEPENDENT EXPRESSION
STRUCTURE OF THE RAT OSTEOCALCIN GENE AND REGULATION OF VITAMIN-D-DEPENDENT EXPRESSION
复制标题
DOI：
10.1073/pnas.86.4.1143
复制
发表时间：
1989-02-01
影响因子：
11.1
通讯作者：
STEIN, G
中科院分区：
文献类型：
--
作者：
LIAN, J;STEWART, C;STEIN, G
骨钙素基因编码 6-kDa 多肽，它代表最丰富的非胶原骨蛋白之一，目前的研究证实骨钙素 mRNA 仅在骨组织中检测到。从大鼠基因组 DNA 文库中分离出骨钙素基因，序列分析表明该 mRNA 存在于由 4 个外显子和 3 个内含子组成的 953 个核苷酸的 DNA 片段中。基因 5'' 侧翼序列的模块化组织反映在至少三类调控元件的存在上，其中包括： (i) RNA 聚合酶 II 规范序列； (ii)一系列与骨钙素基因的生理表达一致的激素受体结合位点和环核苷酸反应元件的共有序列； (iii) 近端启动子区域的 24 核苷酸序列，以 CAAT 基序作为中心元件。我们将这个高度保守的序列指定为“骨钙素盒”，因为在大鼠和人骨钙素基因中仅发现2个核苷酸取代。我们已经证明了调节骨钙素基因表达的两个因素。首先，与非矿化基质中汇合的成骨细胞相比，正常胎儿颅盖成骨细胞产生矿化基质的数量增加了 200 倍。其次，紧邻转录起始位点上游的 600 个核苷酸内包含支持 1,25-二羟基维生素 D 刺激基因转录 10 倍的序列。
The osteocalcin gene encodes a 6-kDa polypeptide, which represents one of the most abundant noncollagenous bone proteins, and the present studies establish that osteocalcin mRNA is detected only in bone tissue. An osteocalcin gene was isolated from a rat genomic DNA library, and sequence analysis indicated that the mRNA is represented in a 953-nucleotide segment of DNA consisting of four exons and three introns. A modular organization of the 5'' flanking sequences of the gene is reflected by the presence of at least three classes of regulatory elements, which include the following: (i) RNA polymerase II canonical sequences; (ii) a series of consensus sequences for hormone receptor binding sites and cyclic nucleotide responsive elements consistent with physiologic expression of the osteocalcin gene; and (iii) a 24-nucleotide sequence in the proximal promoter region with a CAAT motif as a central element. We have designated this highly conserved sequence as an "osteocalcin box" since only 2 nucleotide substitutions are found in the rat and human osteocalcin genes. We have demonstrated two factors regulating osteocalcin gene expression. First, a 200-fold increase occurs in normal fetal calvaria osteoblasts producing a mineralizing matrix, compared to confluent osteoblasts in a nonmineralizing matrix. Second, contained within the 600 nucleotides immediately upstream from the transcription start site are sequences that support a 10-fold stimulated transcription of the gene by 1,25-dihydroxyvitamin D.