OSTEOBLAST NUCLEAR MATRIX REGULATION OF COLLAGEN

胶原蛋白对成骨细胞核基质的调节

• 批准号: 6350697
• 负责人: JOSEPH P BIDWELL
• 金额: $ 20.09万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-02-01 至 2004-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6350697
• 关键词: 3T3 cells; DNA binding protein; bone density; collagen; gel mobility shift assay; genetic promoter element; genetic regulatory element; genetic transcription; genetically modified animals; hormone regulation /control mechanism; laboratory mouse; laboratory rat; nuclear matrix; nucleic acid probes; osteoblasts; parathyroid hormones; protein binding; protein biosynthesis; protein structure function; southern blotting; statistics /biometry; transcription factor

Intermittent doses of parathyroid hormone (PTH) increase bone mass by selectively stimulating bone formation. The molecular mechanisms mediating this anabolic effect are unknown. Demonstrating this phenomenon is problematic using in vitro models because PTH attenuates collagen synthesis in osteoblast culture. Cell structure influences collagen synthesis and likely contributes to the opposing responses of bone and cultured osteoblasts to PTH. We propose that collagen expression is coupled to cell structure via the tissue matrix, the interlinking proteins of the extracellular matrix, cytoskeleton, and nuclear matrix. Furthermore, we propose that this structural pathway culminates with nuclear matrix architectural transcription factors, proteins that alter gene activity by bending promoter DNA in response to changes in tissue matrix organization. Therefore, PTH-induced changes in tissue matrix proteins may alter COL1A1 expression by "tugging" at the gene and altering promoter geometry. We have identified a novel family of nuclear matrix architectural transcription factors, NP/NMP4, that bind with sequence specificity to the promoter of the rat alpha1 (I) polypeptide chain (COL1A1) of type I collagen. These unique zinc finger proteins bind to the COL1A1 promoter, bend it, and contain basal promoter activity. PTH regulates NP/NMP4-COL1A1 binding activity and NP/NMP4 mRNA expression. Hormone-induced alterations in NP/NMP4-COL1A1 binding differ between bone and culture. Our goal is to investigate the functional role of NP/NMP4 in mediating basal and PTH-regulated COL1A1 transcription. The first study will test the hypothesis that the COL1A1 promoter NP/NMP4 binding elements contribute to osteoblast basal and PTH-modulated transcription in vitro and in vivo. The second study will determine the distinct functions of NP and NMP4 in mediating basal and PTH-regulated COL1A1 transcription. The third study will determine the functional domains of the NP/NMP4 proteins. This information will define a structural pathway for PTH action in osteoblasts and further clarify the cellular basis for the anabolic action of this hormone on bone.

间歇剂量的甲状旁腺激素 (PTH) 通过选择性刺激骨形成来增加骨量。 介导这种合成代谢效应的分子机制尚不清楚。使用体外模型证明这种现象是有问题的，因为 PTH 会减弱成骨细胞培养中的胶原蛋白合成。 细胞结构影响胶原蛋白的合成，并可能导致骨和培养的成骨细胞对 PTH 的相反反应。 我们认为胶原蛋白的表达通过组织基质、细胞外基质、细胞骨架和核基质的互连蛋白与细胞结构耦合。 此外，我们提出，这种结构途径以核基质结构转录因子（核基质结构转录因子）达到顶峰，这些蛋白质通过弯曲启动子 DNA 来响应组织基质组织的变化，从而改变基因活性。因此，PTH 诱导的组织基质蛋白变化可能通过“拉动”基因并改变启动子几何形状来改变 COL1A1 表达。我们已经鉴定了一个新的核基质结构转录因子家族 NP/NMP4，它以序列特异性与 I 型胶原蛋白的大鼠 α1 (I) 多肽链 (COL1A1) 的启动子结合。 这些独特的锌指蛋白与 COL1A1 启动子结合，使其弯曲，并包含基础启动子活性。 PTH 调节 NP/NMP4-COL1A1 结合活性和 NP/NMP4 mRNA 表达。 激素诱导的 NP/NMP4-COL1A1 结合改变在骨和培养物之间有所不同。 我们的目标是研究 NP/NMP4 在介导基础转录和 PTH 调节的 COL1A1 转录中的功能作用。 第一项研究将测试以下假设：COL1A1 启动子 NP/NMP4 结合元件有助于体外和体内成骨细胞基础转录和 PTH 调节转录。 第二项研究将确定 NP 和 NMP4 在介导基础转录和 PTH 调节的 COL1A1 转录中的不同功能。 第三项研究将确定 NP/NMP4 蛋白的功能域。该信息将定义成骨细胞中 PTH 作用的结构途径，并进一步阐明该激素对骨的合成代谢作用的细胞基础。