Alvarez M, Thunyakitpisal P, Morrison P, Onyia J, Hock J, Bidwell J P
Department of Oral Biology, Indiana University School of Dentistry, Indianapolis 46202, USA.
J Cell Biochem. 1998 Jun 1;69(3):336-52. doi: 10.1002/(sici)1097-4644(19980601)69:3<336::aid-jcb11>3.0.co;2-a.
In connective tissue, cell structure contributes to type I collagen expression. Differences in osteoblast microarchitecture may account for the two distinct cis elements regulating basal expression, in vivo and in vitro, of the rat type I collagen alpha1(I) polypeptide chain (COL1A1). The COL1A1 promoter conformation may be the penultimate culmination of osteoblast structure. Architectural transcription factors bind to the minor groove of AT-rich DNA and bend it, altering interactions between other trans-acting proteins. Similarly, nuclear matrix (NM) proteins bind to the minor groove of AT-rich matrix-attachment regions, regulating transcription by altering DNA structure. We propose that osteoblast NM architectural transcription factors link cell structure to promoter geometry and COL1A1 transcription. Our objective was to identify potential osteoblast NM architectural transcription factors near the in vitro and in vivo regulatory regions of the rat COL1A1 promoter. Nuclear protein-promoter interactions were analyzed by gel shift analysis and related techniques. NM extracts were derived from rat osteosarcoma cells and from rat bone. The NM protein, NMP4, and a soluble nuclear protein, NP, both bound to two homologous poly(dT) elements within the COL1A1 in vitro regulatory region and proximal to the in vivo regulatory element. These proteins bound within the minor groove and bent the DNA. Parathyroid hormone increased NP/NMP4 binding to both poly(dT) elements and decreased COL1A1 mRNA in the osteosarcoma cells. NP/NMP4-COL1A1 promoter interactions may represent a molecular pathway by which osteoblast structure is coupled to COL1A1 expression.
在结缔组织中，细胞结构有助于I型胶原蛋白的表达。成骨细胞微结构的差异可能解释了在体内和体外调节大鼠I型胶原蛋白α1(I)多肽链（COL1A1）基础表达的两个不同顺式元件。COL1A1启动子构象可能是成骨细胞结构的最终 culmination。建筑转录因子与富含AT的DNA小沟结合并使其弯曲，改变其他反式作用蛋白之间的相互作用。同样，核基质（NM）蛋白与富含AT的基质附着区域的小沟结合，通过改变DNA结构来调节转录。我们提出，成骨细胞NM建筑转录因子将细胞结构与启动子几何形状和COL1A1转录联系起来。我们的目标是在大鼠COL1A1启动子的体外和体内调节区域附近鉴定潜在的成骨细胞NM建筑转录因子。通过凝胶迁移分析和相关技术分析核蛋白与启动子的相互作用。NM提取物来自大鼠骨肉瘤细胞和大鼠骨骼。NM蛋白NMP4和一种可溶性核蛋白NP均与COL1A1体外调节区域内且靠近体内调节元件的两个同源聚（dT）元件结合。这些蛋白在小沟内结合并使DNA弯曲。甲状旁腺激素增加NP/NMP4与两个聚（dT）元件的结合，并降低骨肉瘤细胞中COL1A1 mRNA的水平。NP/NMP4与COL1A1启动子的相互作用可能代表了一种分子途径，通过该途径成骨细胞结构与COL1A1表达相耦合。
